United States
Environmental Protection
Agency
Environmental Research
Laboratory
Duluth MN 55804
EPA-600-3-80-062
July 1980
Research and Development
Lake Erie Nutrient
Control Program

An Assessment of Its
Effectiveness  in
Controlling Lake
Eutrophication
     LIBRARY
     U. S. EWVIROJMSHTA
     BDISW.I.J, pg817

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                RESEARCH REPORTING SERIES

Rc-searcn reports of tne Office of Research and Development. U S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironrnentai technology  Elimination  of traditional grouping was consciously
planned to tostei technology transfer and a maximum' interface in  related fields.
      1   Environmental  Health Effects Flesearch
      2   Environmental  Protection Technology
      3   Ecological Research
      4   Environmental  Monitoring
      &   Sooioeconomic Environmental Studies
      6.  Scientific and Technical Assessment Reports (STAR)
      1   Interayency Energy-Environment Research and Development
      •;:    Soeeai Reports
      9   Miscellaneous  Reports

This report has been assigned to the ECOLOGICAL RESEARCH series This series
describes research on the effects of pollution on humans, plant and animal spe-
cies. and materials. Problems are assessed for their long- and short-term influ-
ences Invest ga'ions include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia  22161.

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                                          EPA-600/3-80-062
                                          July 1980
    LAKE ERIE.NUTRIENT CONTROL PROGRAM

    An Assessment of Its Effectiveness
    in Controlling Lake Eutrophi cation
                Edited by

          Charles E. Herdendorf
    Center for Lake Erie Area Research
        The Ohio State University
           Columbus, Ohio  43210
            Grant No. R-802543
             Project Officer

             Nelson A. Thomas
       Large Lakes Research Station
Environmental  Research Laboratory - Duluth
       Grosse He, Michigan  48138
ENVIRONMENTAL RESEARCH LABORATORY - DULUTH
    OFFICE OF RESEARCH AND DEVELOPMENT
   U.S.  ENVIRONMENTAL PROTECTION AGENCY
         DULUTH, MINNESOTA  55804


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                             DISCLAIMER
      This report has been reviewed by the Environmental Research
Laboratory,  U.S. Environmental Protection Agency, and  approved for
publication.  Approval does not  signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency,  nor does mention of trade names or commercial products con-
stitute endorsement  or recommendation for use.

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                              FOREWORD
      The Great  Lakes comprise approximately 20 percent of the
world's fresh water supply; therefore,  it is of critical importance
to protect the Great Lakes for their various uses.  Of all  the
Great  Lakes, Lake Erie has been stressed  to the furthest extent
as a result of man's activities.  This  report  provides an insight
into the processes that go on within  Lake Erie and our attempt
to describe them.   As we better describe the processes  that go
on within  the Great Lakes,  we will  be  in a  better position  to
understand and predict the management of Great  Lakes systems.
                                   Herbert A. Jaworski, Ph.D.
                                   Director
                                   Environmental  Research  Lab
                                   Duluth, Minnesota
                                  ill

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                              ABSTRACT
      A three-year assessment of nutrient control efforts was conducted
 in the western and central basins of Lake Erie during the period June
 1973 to June 1976. The objective of the study was to determine recent
 trends in lake eutrophication and water quality which may be related to
 recent attempts to control nutrient loadings to these basins.  The assess-
 ment was accomplished by visiting approximately 50 stations at nearly
 monthly intervals during the ice-free  periods.  Over 25 water quality,
 meteorological and biological parameters were routinely determined
 shipboard or on samples collected at a typical station.  Measurements
 were taken at several depths in order to  characterize the various
 strata of water in the lake and to permit  volume-weighted calculation
 of nutrient concentrations and quantities. Data from previous limno-
 logical surveys as far back as 1928 were compared with the results of
 the present study to establish long-term  trends, as well as recent
 trends since the last comprehensive survey in 1970.

      The fundamental  conclusion of this assessment is that during the
 first half of this decade no significant decrease in the loading of nutrients
 to Lake Erie has taken place.  Therefore, during this period the con-
 centrations and quantities of nutrients within the waters of the lake have
 remained relatively stable.  An encouraging sign of nutrient control is
 that although no decreases have been observed, the constant increases
 which have taken place in preceeding decades have been stopped.  Other
 indicators of eutrophication, such as hypolimnetic oxygen depletion rates,
 chlorophyll  concentrations, methane production, plankton and benthos
 populations, dissolved  solids and turbidity,  have remained high since
 1970 but also relatively stable.

      Most of the nutrient loading to Lake Erie occurs in the western
 basin. The largest quantity Is delivered  by the Detroit River, but the
 highest concentrations  were observed  near the mouth of the Maumee
 River.  The western  and central basins are effective sinks for nutrient
 loading; approximately 82 percent of the  phosphorus carried to the lake
 by the tributaries remains in bottom sediments. Up to 10 percent of
the phosphorus delivered to the lake can be regenerated under anoxic
 conditions.  However,  physical regeneration due to storm resuspension
 of sediment can have a larger impact on  internal nutrient loading, par-
ticularly during non-stratified  periods.
                                   iv

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      Meteorological variations, such as wind, solar radiation and pre-
cipitation, appear to have a much more profound effect on the trophic
status of Lake Erie than attempts at nutrient control.  For example,
in 1975 light winds during the period of thermocline formation resulted
in a thicker hypolimnion in the central  basin.  This increased reservoir
of oxygen reduced the area of anoxia by over 95 percent and thereby
decreased the amount of regenerated phosphorus from the sediments by
over 70 percent from the previous two  years.  Also,  because of high
concentrations of nutrients in the lake, particularly the western basin,
the limiting factor in algal production appears to be sunlight. Pre-
cipitation also plays a role  in nutrient  concentrations; high rainfall
in the early 1970's over the upper Great Lakes basins resulted in
record-high flow rates in the Detroit River in  1972 and 1973. The
concentration of nutrients, although not the quantity,  was lowest dur-
ing this period from dilution by excessive precipitation.

      Although the effectiveness of nutrient controls in reversing
eutrophication in Lake Erie cannot be demonstrated,  the halting of
further degradation  is an important first step.  Also,  many new
treatment facilities are just  now being  placed in operation.   Modifi-
cations in agricultural practices will reduce the loading of nutrients
to the tributaries, but these  changes will not be reflected in  water
quality improvements for several years due to  the slow migration of
sediment to the lake.  It is important that this start at improving the
conditions of Lake Erie be continued and that new methods of lake
restoration be explored.

      This  report was submitted  in fulfillment of Grant No. R802543
by The  Ohio State  University,  Center for Lake Erie Area Research,
under the partial  sponsorship  of  the U.S. Environmental  Protection
Agency.   This report covers a period from June 15,  1973 to June 14,
1976  and work was completed  as of April 27,  1979.

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                            CONTENTS
Foreword	    m
Abstract   	     1v
Figures	   viii
Tables	   xix
Acknowledgements	xxvi

   1 .   Lake Erie Nutrient Control Assessment:
          An Overview of the Study
          Charles E. Herdendorf	      1
   2.   History of Lake Erie Water Quality
          Clarence E. Taft	     64
   3.   Oxygen  Depletion and Anoxia in the Central and
          Western Basins of Lake Erie,  1973-1975
          John E.  Zapotosky and Charles E. Herdendorf  ...     71
   4.   Transparency,  Conductivity and Temperature Surveys
          in the Central and Western  Basins of Lake Erie
          John E.  Zapotosky	    103
   5.   Lake Erie Winds:  A Preliminary Analysis 1973-1975
          Daniel L. Wise   	    118
   6.   Phosphorus Budget of the Central and Western Basins
          Of Lake Erie:  1973-1975
          Karlis Svanks	    131
   7.   Chlorophyll a. and Pheopigment Distribution in the
          Central and Western Basins of Lake Erie
          Laura A.  Fay and  David E. Rathke	    175
   8.   Primary Productivity  Survey  of the Central and
          Western Basins of  Lake Erie
          Clifford T.  Sheffield and Walter E.  Carey  ....    231
   9.   Zooplankton Distribution in the Central and Western
          Basins of  Lake Erie
          Donna D.  Larson and  David E. Rathke	    272
  10.   Benthic  Macro invertebrate Distribution  in the
          Central  and  Western Basins of Lake  Erie
          N.W. Britt, A.J.  Pliodzinskas and E.M.  Hair   .  .   294
  11.   Statistical  Analysis of the 1975  Intercomparison
          Study on Lake  Erie
          Paul  I.  Feder and John  E. Zapotosky  	331

                                vii

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                                FIGURES
Number                                                            Page

   1    Monitoring stations location map for the central
          and western basins of Lake  Erie	          4
   2   Schematic  representation of sampling  depths  in
          Lake Erie	         12

   3   Water quality grids used for area- and volume-
          weighted calculations in  the  central and  western
          basins of Lake Erie	,,	         14

   4   Trends  in  anoxic hypolimnion of  Lake Erie
          1930-1974	         16

   5   Relationship between dissolved  oxygen concentrations
          in the lower hypolimnion of  central Lake Erie
          and soluble reactive phosphorus regeneration,
          cruises  7 and 8, August 12-September 5,  1974 .  .         21

   6   Concentration of soluble reactive phosphorus  and
          dissolved oxygen in  the  central basin hypolimnion
          of  Lake  Erie -  1974  	         22

   7   Bottom  dissolved oxygen,  cruise  4,  August 27-
          September 7, 1975	         24

   8   Daily resultant wind at  Long Point,  Ontario for
          April,  May and  June 1973-1975	         27

   9   Quantity of phosphorus in  Lake Erie,  1970-1975 ...         29

  10   Total phosphorus concentrations in Lake  Erie,
          1970-1975   	         30

  11   Total phosphorus concentrations in Lake  Erie,
          1973-1975   	         34

                                  vi i i

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                            FIGURES CO N'T
Number                                                            Page

  12   Total phosphorus quantity  in  Lake Erie,
          1973-1975   	          34

  13   Volume weighted quantity (metric tons)  of total
          phosphorus in Lake Erie  1974-1975   	          36

  14   Soluble reactive phosphorus  concentrations  in
          Lake Erie,  1974-1975 .	          37

  15   Soluble reactive phosphorus  quantity in Lake
          Erie,  1974-1975   	          37

  16   Concentration of chlorophyll  a. in Lake  Erie
          surface water, 1973-1975 ~	          45

  17   Trends in Lake Erie surface water chlorophyll
          1967-1974   	          45

  18   Volume weighted concentration (ug/l) of corrected
          chlorophyll a in Lake Erie 1973-1975	          47

  19   Volume weighted quantity (metric tons)  of corrected
          chlorophyll a in Lake Erie 1973-1975	          47

  20   Total phytoplankton populations at Put-in-Bay  ....          ^4

  21    Bacillariophycean populations at  Put-in-Bay	          54

  22   Chlorophycean populations  at  Put-in-Bay	          55

  23   Myxophycean populations at Put-in-Bay	          55

  24   Bottom dissolved oxygen,  cruise 1, March  18-
          April 25,  1975	          72

  25   Bottom dissolved oxygen,  cruise 2, June 2-
          June 19,  1975   	          72

  26   Bottom dissolved oxygen,  cruise 3, July 13-
          July 24,  1975   	          73
                                  IX

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                             FIGURES CON'T
Number                                                            Page

  27   Bottom  dissolved oxygen,  cruise  4,  August 27-
          September 7, 1975. ...............         73

  28   Bottom  dissolved oxygen,  cruise  5,  September 27-
          October 6, 1975   ................         77

  29   Bottom  dissolved oxygen,  Cruise 6, December 2-
          December 10, 1975 ...............         77

  30   Temperature profile  at station  no.  73 for May-
          October 1974  ..................         79

  31   Temperature profile  at station  no.  73 for April-
          December 1975  .................         79

  32   Volume comparison for stratification layers in the
          central basin of Lake  Erie 1973-1975 .......         SO
  33   Thermal structure of Lake Erie (°C) ,  profile H,
          cruise 5,  September 3, 1973   ..........         81

  34   Thermal structure of Lake Erie (°C), profile F,
          cruise 1,  June 30-July 1, 1973   .........         82

  35   Thermal structure of Lake Erie (°C), profile G,
          cruise 4,  August  9,  1973  ............         83

  36   Bottom  dissolved  oxygen,  cruise 4,  August 7-
          August 11,  1973   ................         84

  37   Bottom  dissolved  oxygen,  cruise 6,  July 26-
          August 6, 1974   ................         84

  38   Mean volumetric dissolved oxygen depletion  rate
          for the hypolimnion of  the central basin of
          Lake  Erie 1929-1975   ..............         89

  39   Monthly  wind persistence  for dominant direction
          at Long Point, Ontario for 1974 and  1975  ....         93

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                           FIGURES CON'T
Number                                                            Page

  40   Average  and resultant winds at Long  Point,  Ontario
          for  1973-1975	         93
  41    Long  Point winds  for  1973,  1974 and 1975
                                                                     94
  42   Mean monthly air and water temperatures at
          Marblehead, Ohio for  1973-1974	         97
  43    Bottom dissolved oxygen,  cruise  1,  July  1O-12,
          1973	         "

  44    Bottom dissolved oxygen,  cruise  5,  August 20-30,
          1973	         "

  45    Average-area weighted Secchi depth (M)	        104

  46    Great Lakes  basin  average monthly precipitation ...        106

  47    Lake Erie  basin average monthly precipitation ....        107

  48    Specific conductance  in  Lake Erie 1974	        109

  49    Specific conductance  in  Lake Erie 1975	        110

  50    Specific conductance  in  Lake Erie	        112

  51    Air and water temperatures at Put-in-Bay, Ohio
          1973	        113

  52    Air and water temperatures at Put-in-Bay, Ohio
          1974	        114

  53    Monthly resultant wind velocities  for  Long Point,
          Ontario    	        127

  54    Histogram  of resultant winds at Long Point, Ontario,
          April-June 1973-1975	        127

  55    Transects for phosphorus  concentration gradient
          calculations	        138

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                            FIGURES CON'T
Number
                                                                   Page
  56   Epilimnetic phosphorus concentration gradient for
          Lake Erie  central basin	        141

  57   Lake  Erie central basin -  1975,  phosphorus
          transformation	        170

  58   Regeneration and sedimentation rates of particulate
          phosphorus in the central and  western basins of
          Lake Erie  -  1975	        170

  59   Basin subdivisions used for chlorophyll analysis
          1973-1975	        182

  60   Central basin subdivisions  used for  chlorophyll
          analysis,  1973-1975	        182

  61    Average corrected chlorophyll a. (jug/l)  by station,
          1973-1975	        185

  62   Average corrected chlorophyll a Oug/l)  at central
          basin stations, 1973-1975	        185

  63   Corrected chlorophyll a. (jug/l) station means  for
          1973-1975   	        187

  64   Corrected chlorophyll a. (jug/l) average  for  all
          depths  sampled,  cruise  2, July 17-July  24,
          1973	        190

  65   Corrected chlorophyll a (jug/l) average  for  all
          depths  sampled,  cruise  5, August 29-
          September 4, 1973	        191

  66   Corrected chlorophyll a (jug/l) average  for  all
          depths  sampled,  cruise  7, October 14-
          October 24,  1973	        192

  67   Corrected chlorophyll a (jug/l) average  for  all
          depths  sampled,  cruise  2, April  25-May 4,
          1974	        193

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                           FIGURES CON'T
Number                                                            Page

  68   Corrected chlorophyll a (Xig/l) average for all
          depths sampled, cruise 4, June  1-June 10,
          1974	        194

  69   Corrected chlorophyll a^ Oug/l) average for all
          depths sampled, cruise 5, June  28-July 7,
          1974	        195

  70   Correctec chlorophyll £ (ug/l) average for all
          depths sampled, cruise 7, August 12-August 19,
          1974	        196

  71   Corrected chlorophyll a_ (jug/I) average for all
          depths sampled, cruise 8, August 26-
          September 7,  1974	        197

  72   Corrected chlorophyll a_ (;ug/l) average for all
          depths sampled, cruise 1O, October  21-
          November 1, 1974	        198

  73   Corrected chlorophyll a (ug/l), cruise 1A and  1B,
          March 27-April 25, 1975	
  74   Corrected chlorophyll a (jug/I), cruise 2, June 9-
          June 19,  1975   	        20°

  75   Corrected chlorophyll a (;ug/l), cruise 3, July 13-
          July 21,  1975	        201

  76   Corrected chlorophyll a (jug/I), cruise 4, August 3O-
          September 5, 1975	        202

  77   Corrected chlorophyll ei (ug/l), cruise 5, September  27-
          October 6, 1975   	        2O3

  78   Corrected chlorophyll £ (XJg/l), cruise 6, December 2-
          December 14, 1975	        204

  79   FWPCA station  locations, 1967-1968	        212



                                  xi ii

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                            FIGURES CON'T
Number
                                                                   Page
 80    Comparison of central and western basin
         chlorophyll a_ values' (average of surface
         and  mid-depth values)  from FWPCA,  1967
         data and  corresponding 1974 and 1975
         data	        213

 81    CLEAR stations enclosed in  boxes used for
         comparisons with Glooschenko's  1970
         chlorophyll study  t	        214

 82    Comparison of central basin chlorophyll  a
         values from Glooschenko's  1970  data  and
         corresponding  1974 and 1975 data	        219

 83    Comparison of western basin chlorophyll  a
         values from Glooschenko's  1970  data  and
         corresponding  1974 and 1975 data	        219

 84    Particulate organic carbon and corrected
         chlorophyll a_ concentrations -  Lake Erie
         central and western basins,  1973-1975	        222

 85    Particulate organic carbon and corrected
         chlorophyll £ tonnages, Lake Erie  central
         and  western basins, 1973-1975	        223

 86    Lake Erie central basin surface water -  1975:
         corrected  chlorophyll a, particulate phos-
         phorus and particulate organic carbon
         concentrations, area weighted	        224

 87    Lake Erie central basin bottom water -  1975:
         corrected  chlorophyll a, particulate phos-
         phorus and particulate organic carbon
         concentrations, area weighted	        225

 88    Lake Erie central basin bottom water -  1975  ....        226

 89    Lake Erie central basin surface water -  1975  ....        226
                                  xiv

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                            FIGURES  CON'T
Number                                                              Page

  90   Map of Lake  Erie showing  station locations in
          the central and western  basins	
  98   Vertical profile of incubator productivity at
          station  48 on 4 August 1974 and  16 August
          1974
  91    Relationship of in situ productivity to relative
          light intensity near Rattlesnake Island	        244

  92    Relationship of relative  in situ productivity  and
          light transmission of depth near Rattlesnake
          Island	        245

  93    Relationship of sample activity to aliquot volume   .   .        246

  94    Relationship of sample activity to time after
          fixation   	        246

  95    Vertical profile of incubator  productivity at
          station  47 on 30 July 1974 and station 23
          on 13 August 1974   	        249

  96    Vertical profile of incubator  productivity at
          station  25 on 13 August 1974 and  station 30
          on 1 August 1974	        251

  97    Vertical profile of incubator  productivity at
          station  30 on 14 August 1974 and  station 39
          on 27 October  1974	
  99   Vertical profile of incubator productivity at
          station  52 on 27 July  1974 and station  73
          on 30 July 1974 .................        254

 100   Relationship of incubator productivity to
          uncorrected chlorophyll  a concentration at
                                   —
          1 M depth ....................
                                    xv

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                            FIGURES CON'T


Number                                                             Page

 101    Relationship  of  incubator productivity to total
          phosphorus concentration at 1  M depth	        256

 102    Relationship  of  mean relative dark 14C  uptake
          to mean incubator productivity at each  station
          in central and western Lake Erie	        263

 103    Relationship  of  relative dark 14C uptake to  light
          transmission	„	        265

 104    Sub-basin map	        274

 105    Zooplankton collecting stations 1967-1968	        274

 106    1970 zooplankton collecting stations	        276

 107    1968 zooplankton collecting stations	        276

 108    Average zooplankton concentrations in no./m3 by
          sub-basin	        278

 109    Average rotifer concentrations in  no./m3  by
          sub-basin	        282

 110    Average cladoceran  concentrations  in no./m3  by
          sub-basin  	
111   Average copepod concentrations  in no./m3  by
         sub-basin	        287

112   Average benthic macro invertebrate  diversity   ....        3O°

113   Distribution of surficial  sediments	        30°

114   Prevailing  annual bottom flow	        301

115   Lake Erie  bathymetry	        301

116   Average percent oligochaeta in the  bottom fauna . .  .        303
                                  xvi

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                           FIGURES  CON'T


Number                                                            Pa9e

 117   Average  benthic macro invertebrate densities
          (indiv./m2)  for central and western basins
          of  Lake Erie 1973-1974	        303

 118   Average  oligochaete density for central and
          western basins of Lake  Erie 1973-1974   	        3O4

 119   Average  percent oligochaetes in the bottom fauna. .  .        304

 120   Average  chironomid density in  central and western
          basins of  Lake Erie 1973-1974	        305

 121   Average  percent of  chironomidae in the  bottom
          fauna	        305

 122   Average  sphaeriid density  in the central and
          western basins of Lake  Erie 1973-1974	        307

 123   Average  percent of  sphaeridae  in the bottom  fauna .  .        307

 124   Average  oligochaete diversity in  the central and
          western basins of Lake  Erie 1973-1974	        308

 125   Distribution of Limnodrilus species in the central
          and western basins of Lake Erie 1973-1974
                                                                    309
 126   Distribution of Oligochaete species in the  central
          and western basins of  Lake Erie 1973-1974   ...        31°

 127   Distribution of Oligochaete species in the  central
          and western basins of  Lake Erie 1973-1974   ...        311

 128   Distribution of mollusca  in the central and western
          basins of Lake Erie 1973-1974	        313

 129   Distribution of chironomidae in the central and
          western basins of Lake Erie 1973-1974	        315

 130   Distribution of minor elements in the central and
          western basins of Lake Erie 1973-1974	        31S
                                  xvn

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                           FIGURES  CON'T
Number                                                            page

 131    Distribution of organic carbon in surficial sediments
          (% dry weight)   .  •.	       317

 132    Bottom dissolved oxygen,  cruise  5,  August 29-
          September 4,  1973	       317

 133    Average  density changes  in central and western
          basins (1973-1974)  during ice-free months  ....       320

 134    Average  diversity  changes in central and western
          basins (1973-1974)	       320

 135    Bottom dissolved oxygen,  cruise  7,  August 12-19,
          1974	       321

 136    Bottom dissolved oxygen,  cruise  8,  August 26-
          September 7, 1974	       321

 137    Extent of organic pollution indicated by tubificid
          index  (Wright, 1955)	       324

 138    Lake  Erie benthic  population distribution  1963-1964.  .       325

 139    Average  density Lake  Erie benthic populations
          1963-1964	       326

 140    Average  density benthic macroinvertebrates in
          western  and central Lake Erie 1973-1974	       326

 141    Temperature profile (°C) Secchi  depths and
          sampling  sites	       333
                                 xvm

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                                TABLES
Number                                                            Page

   1    Limnological Parameters Monitored  in the
          Central  and Western  Basins of  Lake Erie	         3

   2    Geographical Coordinates for Stations  in the
          Central  and Western  Basins of  Lake Erie	         5

   3    Lake  Erie  Cruise Schedules for 1973-1975	         7

   4    Stations Occupied in  the Central and Western
          Basins  of Lake Erie  in 1973-1975	         8

   5    System of  Parameters Used to Index the  State
          of  Eutrophication in Lake Erie    	         9
   6   Estimated Area of the Anoxic  Hypolimnion of the
          Central  Basin of Lake Erie  1930-1974  ......        17

   7   Trends  in Net  Oxygen Demand  of the Central
          and Eastern Basin Hypolimnions of Lake Erie   .  .        19

   8   Comparison of 1973, 1974 and  1975  Characteristics
          of  Hypolimnion in Central  Lake Erie  .......        25

   9   Phosphorus  Budget for  the Western and  Central
          Basins of Lake  Erie,  May-September 197O-1975  .        31

  10   Concentration and Quantity of Total Phosphorus
          in  Western and  Central Lake Erie -  1975   ....        33

  11    Ten-Year Comparison of Mean  Water Quality in
          Lake Erie   ...................        43
  12   Average  Surface Chlorophyll  a in  Lake Erie -
          1973
                                 Xix

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                            TABLES CO N'T
Number                                                           Page

  13    Ratio  of Chlorophyll a. Concentration in Western and
          Central Basins  of  Lake Erie 1973-1975    	        48

  14    Summary  of  1973  Hypolimnetic Surveys of the
          Central Basin of Lake Erie	        74

  15    Summary  of  1974  Hypolimnetic Surveys of the
          Central Basin of Lake Erie	        75

  16    Summary  of  1975  Hypolimnetic Surveys of the
          Central Basin of Lake Erie	        76

  17    Sample Calculation for  Mesolimnion  Exchange
          Model  for  Lake Erie  Hypolimnion Oxygen
          Depletion  for July  16-September 1,  1975   ....        85

  18    Hypolimnetic  Oxygen Depletion Rates in the
          Central Basin of Lake Erie (1973-1975)   . . . .  „        87

  19    Hypolimnetic  Oxygen Central Basin of  Lake
          Erie 1974  and 1975 Values = kgO2 x 1O6	        92

 20    Monthly Average Air-Water Temperature
          Difference  °C - Marblehead and Put-in-Bay,
         Ohio	        96

 21    Specific  Conductance  in the Central and Western
         Basins of  Lake  Erie,  1974-1975	        108

 22    Results of the Wind Analysis for Various Periods
         at Long Point,  Ontario:  1973-1975	        124

 23    Percent Frequency of the 8-Point  Wind Directions
         Derived from Hourly Wind  Data for  Long Point,
         Ontario, April-December, 1973-1975	        126

 24    Concentration  and Quantities of Phosphorus Forms
         in Lake Erie Central  Basin	        133

 25    Total Phosphorus Input in Lake Erie Metric Tons  .  .        135
                                  xx

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                           TABLES CON'T
Number                                                           Page

  26    Lake Erie Western and Central Basin Average
          Daily Total and Soluble Reactive Phosphorus
          Loads Metric Tons  -  1975   	       136

  27    Flow Rates of Water into Lake  Erie	       137

  28    Average Phosphorus Concentration  in  Lake Erie
          Central Basin at Transects  1 through 6  in PPB .  .       140

  29    CLEAR  Nutrient Cruise Timetable	       144

  30    Lake Erie Western Basin Total Phosphorus Budget
          (Metric Tons) July  17-October 24,  1973	       145

  31    Lake Erie Central Basin Total Phosphorus Budget
          (Metric Tons) July  17-October 24,  1973	       147

  32    Lake Erie Western plus  Central Basin Total
          Phosphorus Budget  (Metric Tons) July 17-
          October 24,  1973	       149

  33    Lake Erie Western Basin Total Phosphorus Budget
          (Metric Tons) April 25-November  1,  1974   ....       150

  34    Lake Erie Central Basin Total Phosphorus Budget
          (Metric Tons) April 25-November  1,  1974   ....       151

  35    Lake Erie Western plus  Central Basin Total
          Phosphorus Budget  (Metric Tons) April 25-
          November  1,  1974  	       153

  36    Lake Erie Western Basin Total Phosphorus Budget
          (Metric Tons) March 27-December 14,  1975  ...       154

  37    Lake Erie Central Basin Total Phosphorus Budget
          (Metric Tons) March 27-December 14,  1975  ...       155

  38    Lake Erie Western plus  Central Basin Total
          Phosphorus Budget  (Metric Tons) March 27-
          December  14,  1974	       158
                                 XXI

-------
                            TABLES CON'T
Number                                                          Page

  39   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 1-2	       159

  40   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 2-O	       160

  41    Lake Erie Central Basin 1975 Phosphorus Budgets,
          Metric  Tons - Cruise 2-3	       161

  42   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 3-4	       162

  43   Lake Erie Central Basin 1975 Phosphorus Budgets,
          Metric  Tons - Cruise 3-4	       163

  44   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 4-5	       164

  45   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 5-6	       165

  46   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 5-6	       166

  47   Lake Erie Central Basin 1975 Phosphorus Budget,
          Metric  Tons - Cruise 1-6	       167

  48   Lake Erie and Central Basin  197O-1975,  May
          through September (5/1-9/30) Mean  Total
          Phosphorus Concentration and Quantities,
          "Anoxic"  Regeneration,  External  Loading
          and  Sink	        171

  49   Total Phosphorus "Anoxic"  Regeneration Associated
          with Anoxic Hypolimnion Lake Erie Western
          and  Central Basin  -  1973,  1974 and 1975   ....        173

  50   Equations  used for  Lake Erie—1973-1975
          Calculations   	        177
                                 xxi i

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                            TABLES CON'T
Number                                                           Page

  51    Corrected Chlorophyll a^ - Volume Weighted
          Concentrations,  1973^-1975   	       180

  52    Corrected Chlorophyll a^ - Volume Weighted
          Concentrations,  1973-1975   	       183

  53    Corrected Chlorophyll a - Station Means  for
          the 15 Cruises,  1973-1975	       184

  54    Percent of  Annual Total Corrected Chlorophyll a
          and  Pheopigment a Contributed at Each Cruise
          Interval  - Central  Basin	       188

  55    Percent of  Annual Total Corrected Chlorophyll a
          and  Pheopigment 
-------
                            TABLES CON'T
Number                                                            Page

  62   CLEAR SCOR/UNESCO Chlorophyll  a (ug/l)
          Volume  Weighted Concentrations.   Basin
          Values Include  all Stations at  all  Depths	        220

  63   Comparison of Primary Productivity  Measure-
          ments in Central and Western  Lake  Erie
          from 1957-1974	        240

  64   Carbon Assimilation Rates  by Station and  Cruise
          for  Central and Western  Lake  Erie in 1974 ....        241

  65   Mean Productivity by Basin from July-October
          1974	        242

  66   Vertical  Distribution of Uncorrected  Chlorophyll a
          Concentration at Stations 30 and 36  in August
          1974	        250

  67   Mean Seechi Disc and  Euphotic Zone Depths for
          Central  and Western  Lake Erie from July-
          October 1974	        258

  68   Lake Erie  Zooplankton  Studies -  Comparative
          Methods	        277

  69   Average  1974 Zooplankton Numbers/m3 by Basin
          and  Cruise	        279

  70   Zooplankton Species Found in Western  and Central
          Basins of Lake Erie,  1974 and 1975	        280

  71    Sampling Periods for  Lake  Erie  Nutrient Study -
          Benthos Cruises   	        295

  72   Taxanomic Groups found  in  Lake  Erie's Western
          and  Central Basins During  Lake Erie Nutrient
          Study (1973-1974)    	        297
                                  XXIV

-------
                            TABLES CON'T
Number                                                           Page

  73    Benthic Fauna Found in  Lake Erie's Western
          and Central  Basins	        298

  74    Benthic Macro invertebrate Diversity in  Lake Erie's
          Western and Central Basins  During Lake  Erie
          Nutrient Study (1973-1974)   	        299

  75    Comparison of Density and Diversity  (Taxa Number/
       m2) for the Western  and  Central  Basins, 1973-1974  .        319

  76    Lake  Erie  Western Basin  Bottom Fauna  1929-1930
          Wright (1955)	        323

  77    Physical and Chemical Parameter Determinations
          Made  by GLL,  CCIW,  CLEAR	        334

  78    Summary of Operational Details of 1975 Lake  Erie
          Intercomparison    	        335

  79    Basic Data on Six Chemical Properties of Water
          Samples	        340

  80    Overall Average Determinations by Site	        344

  81    Subsample, Whole Sample,  Pump-to-Pump
          Variances - By Site   	        346

  82    Analysis Group Averages - By  Site   	        347

  83    Sampling Group Averages  - By Site	        349

  84    Sampling Depth Averages  -  By Site  	        350

  85    Comparison of CLEAR Pump and Water  Bottle
          Measurements - By Site	        352
                                  xxv

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                        ACKNOWLEDGEMENTS
      A project as large and complex as the one discussed in the
following  sections of this report required the dedicated efforts of
many scientists, technicians and clerical  workers.  The  author
gratefully acknowledges the tasks performed  by the  staff  of the
Center  for  Lake Erie Area Research  and other groups at The
Ohio  State  University.  The crew of the R/V Hydra worked
under difficult conditions and for long hours  to obtain the mea-
surements presented herein.  Captains W.P.  Chrysler and
Dennis  Naylon and technicians David Gruet, Gordon Fastzkie,
James Haub and John Gnau are  commended for their service.
Statistical and computer handling of the data were capably undei—
taken by Dr.  Paul Feder,  George Sturm,  David  Lowry and
Thomas Cooper.  Editorial,  drafting and  manuscript preparation
tasks were  skillfully performed  by Patricia Herdendorf, Terry
Glass, Carolyn Jenkinson,  Jo Ann Franks, Marjorie Slagle,  Mary
MacLean, Terry Karpinecz,  Pam Rusch  and  Donna  Martens.

      In addition to these co-workers  the author is particularly
grateful for the guidance, assistance and helpful  suggestions  of
Nelson Thomas (USEPA, Large Lakes Research  Station), Noel
Burns (Canada Centre for Inland Waters) and  Robert Sweeney
(Great Lakes  Laboratory).
                               XXVI

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                              SECTION 1

          LAKE  ERIE  NUTRIENT CONTROL ASSESSMENT:
                   AN  OVERVIEW OF THE STUDY

                        Charles E.  Herdendorf
                 Center for Lake  Erie Area Research
                      The Ohio State University
INTRODUCTION

      In  June 1973, the Center for Lake Erie Area Research (CLEAR)
at The Ohio State University  initiated a comprehensive,  three-year mon-
itoring orogram  of biological  and water quality  parameters  in the central
and western basins of Lake Erie.  At the  same time a companion study
was started  in the eastern basin by the Great Lakes Laboratory (GLL)
of the New York  State University College at Buffalo.  These studies,
sponsored  by the U.S. Environmental Protection Agency, are part of
the Large  Lakes  Research Program (Grosse lie) of EPA's Environmental
Research Laboratory  (Duluth).  The studies were designed to examine
several  indicators of  the trophic status of  Lake Erie and develop a sys-
tem to index the  state of eutrophication in the  lake as a function of
inputs and time.   The objective  of the  investigations is to determine the
effectiveness of the various federal,  state,  and  local nutrient control
programs  in halting the accelerated rate of Lake Erie eutrophication.

      The  water  from Lake Erie sustains the vast industrial complex
which extends from Detroit to Buffalo.  Water returned to the lake is
highly enriched  by municipal, agricultural,  and  industrial waste  pro-
ducts.   Studies conducted  in the late  1920's revealed that the lake was
already  moderately rich  in nutrients and was experiencing phytoplankton
blooms in  its western basin.   Adjacent to  the Detroit River  mouth sen-
sitive mayflies were being replaced by  tubificid worms.   By the mid-
1950's thermal stratification was resulting  in oxygen depletion in the
bottom water and mayfly nymphs suffered catastrophic mortality.  The
concentration of  all the major ions, including the nutrients  phosphorus
and nitrogen, showed  a marked increase during this period of time.

      The  concept of nutrient  control for Lake  Erie appears  to have had

-------
its origin  in 1965,  when the U.S. Department of Health, Education and
Welfare convened a conference  on the pollution of Lake  Erie  and its
tributaries under the  authority granted  in the Water Pollution Control
Act of  1961.   One of the recommendations  forthcoming from  the con-
ference was that  a  "technical committee" be established to evaluate
water quality problems related  to  nutrients in  Lake  Erie and to make
recommendations to the  conferees.  In late 1965  the Lake Erie Enforce-
ment  Technical Committee was formally established to explore  the prob-
lems  related to nutrients and over-enrichment of Lake Erie.   The com-
mittee received information and advice from leading authorities in water-
oriented disciplines, and after a year of study a  final report was issued.
The report concluded  that  the major  pollution problems  in Lake Erie
results  directly or  indirectly  from excess algae and that these  growths
are stimulated by nutrients resulting  from man's activities.

      The  technical  committee recommended that  water quality  objectives
be established  that  would prevent nuisance algae  conditions,  particularly
by lowering the phosphate  and nitrogen levels in  the lake.  The commit-
tee further recommended that new treatment processes be developed and
employed to  effect high phosphate  removal.  Based on these recommen-
dations  the Federal Water Pollution Control Administration (FWPCA)
later  the  Federal Water Quality Administration  (FWQA), and  more
recently the  Environmental Protection Agency (EPA), as well as state
and local agencies,  have embarked on a program to control  the flow of
nutrients  to Lake Erie.  The necessity for  this control has been rein-
forced by  recent  findings of the International Joint Commission and the
Canada-United  States  Water Quality Agreement  of 1972.

STUDY PLAN

      In order to assess the success  of these efforts a study plan was
developed  to monitor  over 20 limnological parameters (Table 1) at
approximately  50 stations  in the central and western basins  of  Lake Erie.
The station locations  were selected to correlate with previous  limno-
logical  studies, e.g.  Project Hypo—a joint USEPA/Canada Centre
for Inland Waters (CCIW)  study of central Lake  Erie in 1970 (Burns  and
Ross,  1972),  and to monitor  areas of nutrient loading and the  sub-
sequent dispersal of these substances throughout  the basins (Figure  1
and Table 2).

      In order to sample this large area, a vessel of sufficient size  to
carry both scientific  equipment and crew for extended periods  of time
was required.   During the 1973 season several boats  were employed on
this study: R/V  Dambach (Great  Lakes Laboratory, SUNY), the R/V

-------
                   TABLE 1 .   LIMNOLOGICAL  PARAMETERS MONITORED IN THE
                          CENTRAL AND WESTERN BASINS OF LAKE ERIE
                   Parameter
                                                    Determ ination Method
oo
Shipboard Sensors
 a.  Te m pe r atu re
 b.  Conductivity
 c.  Dissolved Oxygen
 d.  pH
 e.  Transparency
 f.  Transmissibility
 g.  Light Penetration
Shipboard Laboratory
 a.  Alkalinity
 b.  Ammonia Nitrogen
 c.  Chloride
 d.  Dissolved Silica
 e.  Nitrate + Nitrite
 f.  Sol. Reactive Phosphorus
 g.  Total Phosphorus
Mainland Laboratory
 a.  Particulate  Organic Carbon
 b.  Particulate  Organic Nitrogen
 c.  Chlorophyll _a_,  b,  c,  and Pheopigments
 d.  Primary Productivity
 e.  Phytoplankton Populations
 f.  Zooplankton Populations
 g.  Benthic Macroinvertebrate Populations
 h.  Methane Production (microbial)
 i.  Nitrogen Fixation (microbial) 	   	
BT/Submersible probe (Martek)
Submersible probe (Martek)
Submersible probe (Martek)
Submersible probe (Martek)
Secchi disk
Transmissometer (Martek)
Photometer (Lambda)

Titration (HCl )
AutoAnalyzer (Technicon)
AutoAnalyzer (Technicon)
AutoAnalyzer (Technicon)
AutoAnalyzer (Technicon)
AutoAnalyzer (Technicon)
AutoAnalyzer (Technicon)

Elemental  analyzer (Perkin-Elmer)
Elemental  analyzer (Perkin-Elmer)
Spectrophotometer (Varian Techtron)
Shipboard  incubation/  C,  GM counter
Niskin bottle/Inverted microscope
Vertical  net tow/Dissecting microscope
Ponar dredge/Dissecting microscope
Gas chromatograph (Varian)
Gas chromatograph (Varian)	

-------
20   0  20  4O   <0   W
I....I....T ill
Figure 1.  Monitoring stations location map  for the central

            and western  basins of  Lake Erie.

-------
TABLE 2.   GEOGRAPHICAL COORDINATES FOR STATIONS
IN THE CENTRAL AND WESTERN  BASINS OF  LAKE ERIE
Station No.
23
24
25
26
27
28
29

31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
65
66
67
6a
6)
TO
71
72
73
74
75
76
77
78
79
to.
82
83
64
Latitude (North)
42° 02« 48"
42° 05' 54"
42 14' 54"
42° 24' 00"
42° 32' 54"
42 35' 30"
42 36' 18"
42° 25' 48"
42° 15- U"
42° 04' 54"
41° 551 54"
41 50' 00"
41° 45' 48"
41° 56' 06"
42° 06' 36"
42 16' 54"
42° 21 • 30"
42° 11' 30"
42° 08' 06"
41° 57' 54"
41 471 18"
41° 31' 48"
41° 36' 24"
41° 40' 54"
41° 50' 18"
42° 02' 48"
41° 55' 54"
41 48' 48"
41° 38' 30"
41° 311 54"
41 25' 12"
41° 34' 00"
41° 44' 18"
41° 54« 42"
41° 49' 54"
41 41' 06"
41° 43' 36"
41° 53' 30'
41° 561 48"
4i° 391 oo"
41° 58' 00"
41° 40' 00"
41° 45« 00"
41° 33' oo-
41 46' 00"
42° 1B« 00"
41° 57' 50"
41° JBl 40"
41° 40' 00"
41° 54' 00"
41° 36' 30-
41° 39' 3°'
42 07' 00"
42° 15' 00"
41° 36' *•
41° 34' 3°"
41 42» 30"
41° 45» 36"
Longitude (West)
80° 27' 0 •
80° 29' 00"
80° 33' 36"
80 38' 12"
80° 45' 30"
81° 01 « 00"
81° 17' 54"
81° 12' 18«
81° OC' T<"
81° 00' 42"
eo° 55« oo"
81° 08' 54"
81° 23' 00"
81° 28« 42"
81° 34' 30"
81 40' 18"
81° 42' 24"
ft
81 55' 18"
82° 08' 24"
82° 02' 30"
81° 56' 42"
81° 42« 30"
81° 53' 48"
82 05' 12"
82° 12' 48"
82° 21« 54"
82° 24' 30"
82° 30« 06"
82° 24' 12"
82° 27' 12"
82° 30' 12"
82° 38' 06"
82° 44' 00"
82° 50' 24"
833 01 « 06"
82° 56' 00"
83° 09' 00"
83° lit 48"
83° 02' 42"
82° 44« 00"
82° 40' 00"
82° 52' 00-
82° 51' 00"
82° 55« TO"
83 20' 00"
81° 22' 20"
81° 11' 00"
81° 45' 25"
82° 35' 00"
83 18« 00"
83° 04' 00"
82° 49' 36"
81 15' 00"
80° 48' 00"
82° 50» 40"
82° 10' 00"
82° 191 10"
83° 19' 42"
Basin
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
V
V
H
w
V
w
w
w
V
w
V
w
w
C
C
C
C
V
₯
M
C
C
C
C
C
₯
Grid Ho.
19
19
20
20
21
22
22
23
24
25
26
26
27
28
29
30
31
32
32
33
34
36
35
37
38
39
39
40
41
43
42
43
44
45
48
46
47
49
50
43
45
46
46
46
49
23
26
y
43
49
46
46
24
20
46
41
38
47

-------
Maple (Great Lakes Research Division,  University of Michigan), the
P/B Bluewater (Grosse  lie Laboratory,  USEPA),  and the R/V Hydra
(CLEAR, Ohio  State  University).   The latter  vessel,  a modified U.S.
Army  cargo lighter leased from USEPA  (Region V), was outfitted  with
a  nutrient chemistry  laboratory and specialized sampling  apparatus for
the 1974 and 1975 field  seasons.  Nine cruises were  completed during
1973,  eleven in 1974  and  six in 1975 (Table 3).   A total  of 1,092  rou-
tine station  visitations were made during the three-year study (Table
4).

      Each  of the limnological  parameters that were monitored  has its
influence on the process of eutrophication.  Correlation of biological
data with the chemical  and physical characteristics was formulated to
assess the  value of each parameter as an index of the trophic state of
the lake (Table  5).

      The biological parameters measured consist  of:   (1) planktonic and
benthic organisms,  (2)  primary productivity, (3) chlorophyll,  and (4)
nitrogen-fixation and  methane production  by  microbial organisms.   The
plankton segment of this study  examined  the distribution,  types and
quantity of  phyto- and zooplankton.  The  predominance of any species
or  communities known to  be associated with lake  aging  or marked
changes in  populations is  used  as  a trophic  index.  Information derived
from  cell volume estimates,  chlorophyll  a measurements, and carbon-
14  studies provides the  basis for  estimates  of standing  crops and  pri-
mary productivity.  Additional  information on  the  status of the  lake is
supplied by  benthic communities.   These communities are relatively
immobile and some members have relatively long  life spans  (as com-
pared  to  plankton).   Thus, benthic macroinvertebrate  occurrence and
density provide  some measure  of  water quality over a prolonged period
of time.  In addition  a measure of the trophic conditions  of the lake
can be  calculated in terms of species diversity and changes  in this
diversity.  Other biological  indicators used  in this  assessment of  abate-
ment effectiveness are certain  microbial  forms and their  activities.
Analysis  of biological nitrogen  fixation has shown  that forms capable
of this  activity  are  favored by  environments in which  nutrient input is
significant.   A  similar biological  activity closely  associated with waters
receiving nutrient inputs  is the production of methane.  Methane-pro-
ducing bacteria  are primary stabilizers of fresh organic matter desposi-
ted in  sediments.   The  assessment of methane production in sediments
gives an  indication  of loading of sediments with fresh, readily decom-
posable organic  matter.

     The chemical  parameters considered are those involved as neces-

-------
TABLE 3.  LAKE ERIE CRUISE SCHEDULES FOR 1973-1975
Cruise
1
2
3
4
5
6
7
8
9
10
.11
Year
1973
June 28 - July 12
(179-193)
July 17 - July 23
(198-204)
July 25 - August 2
(206-214)
August 7 - August 1 1
(219-223)
August 29 - September 4
(241-247)
September 19 - September 29
(262-272)
October 14 - October 24
(287-297)
November 7 - November 1 5
(311-319)
December 4
(338)


1974
April 7 - April 17
(097-107)
April 25 - May 4
(115-124)
May 14 - May 24
(134-144)
June 1 - June 10
(152-161)
June 28 - July 7
(179-188)
July 26 - August 4
(207-216)
August 12 - August 19
(224-231)
August 26 - September 7
(238-250)
September 24 - September 27
(267-270)
October 21 - November 1
(294-305)
December 11 - December 14
(345-348)
1975
March 18 - March 31
(077-090)
June 9 - June
(160-170)
July 13 - July
(194-205)
19
24
August 27 - September
7 (239-250)
September 27
6 (27O-279-)
December 4 -
10 (338-344)
- October
December






-------
TABLE 4.   STATIONS OCCUPIED IN THE CENTRAL AND
    WESTERN  BASINS OF  LAKE ERIE IN 1973-1975
itatiorf^-^
23
24
26
27
26
29

£

35
36
37
#
39
10
U
12
•3
14
9
16
•7
18
19
50
51
V
'3
*
% 	
'7
*
Iff
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>i
tf
i
36
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4
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X X
X X
X X
X
X
X
X
X X


X
X

X

X X
X
X



1
X
••x"
X
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X
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X
X
X
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X
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x
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X
1975
2 3
X X
X1 «X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
x x
X X
X X
X X
X X
X X
X X
X X
X X
x x
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
x x
X X


X X
X X
X X
X X

X X
X X
X X



4 5 6
xxx
X 7 ~T
X X
xxx
xxx
X X
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xxx
xxx
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X X
xxx
xxx
X X
xxx
xxx
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xxx
xxx
xxx
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X X
xxx
xxx
X X
xxx
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xxx
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X X
xxx

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xxx
xxx
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X X

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-------
     TABLE  5.   SYSTEM OF PARAMETERS  USED TO INDEX
          THE  STATE OF  EUTROPHICATION  IN  LAKE  ERIE
                                 Physical Measurements
                                            T
Temperature:  measured  on station at one-meter depth intervals  ...  exerts control
      on biological activities; identifies location of thermocline

pH;  measured on station at various depths (one meter intervals)... affects bio-
      logical activity; may reflect rate of photosynthesis

Conductivity:   measured on station at various depths  (one meter intervals).. .a
      measure of dissolved  material  that will conduct an electrical  current
                                            I
Light Penetration:  measured on selected stations  at  various  depths (one-meter
      Intervals).. .energy source for conversion  of inorganic  materials  into the
      blomass
Transmissibility:  measured on station at various depths (one-meter Intervals).,
      an indicator  of concentration of suspended  solids

Wind Direction & Velocity,  Estimate of Wave Height and Period:   measured on
      station.. .important factors  in mixing of  lake water
                                  Water Chemistry
Dissolved Oxygen;  measured on station at various depths (one-meter  intervals)
      ...depletion of oxygen, particularly  In the hypolimnion beneath the thermo-
      cllne,  limits higher life  forms        I

Alkalinity:  water sampled on  station, analyzed underway.. .buffer to control  pH;
      a measure of calcium  bicarbonate  in lake (an alternative  nutrient for algae)

Soluble Reactive  Phosphorus:  water sampled  on  station; analyzed underway;
      phosphorus  is currently considered to be primary  cause  of eutrophication
      as a nutrient of  phytoplankton
Total Phosphorus:  water sampled on station;  analyzed on board. In port

Ammonia:  water sampled on station; analyzed underway.. .indicator of nitrogen
      concentration,  breaks down to nitrate/nitrite, Indicator of relatively recent
      pollution
Nitrate/Nitrite:  water sampled on station; analyzed underway.. .nitrogen Is a pri-
      mary nutrient  for phytoplankton
Partlculate, organic,nitrogen and carbon;  water sampled on station, analyzed
      In Columbus... ratio of the  parameters  Indicative of nutritional potential
      of the lake

                                                             (continued)

-------
                                TABLE 5 (continued)
                                  Biological Parameters
Benthos:   sampled on  station, analyzed on mainland.. .particular groups of midges
      withstand different eutrophic conditions; the particular groups  present,  and
      their relative abundance may indicate state of eutrophication

Plankton:  sampled on station,  analyzed on mainland.. .species of phyto- and zoo
      plankton present, and their relative abundance may also indicate  state of
      eutrophication

Primary Productivity:   water sample (containing  phytoplankton) obtained on station,
      NaCOg tagged with radioactive carbon added,  sample  incubated and cells
      filtered on shipboard,    C in cells  counted on mainland. . .primary  productivity
      is  rate  of incorporation of inorganic carbon into molecules of living cells
      (Increase of biomass); another indicator of  state of eutrophication

Microblal  Activity (methane production  &  nitrogen fixation):   water  sampled on
      station, analyzed underway with gas chromatograph (some  samples  analyzed
      on mainland). , .fixation  of inorganic nitrogen into  an organic form of primary
      productivity; methane is produced by bacterial action  on decaying organic
      matter that has sunk to the bottom, its concentration may therefore be indi-
      cative of  past plankton populations    I

Chlorophyll a,  b,  and  c: Water sample obtained on station,  analyzed on mainland
      by spectrophotometer.. .measurement of these  pigments can provide  insight
      into  relative amount  of  standing crop of algae,  results to be  correlated with
      primary productivity study and phytoplankton study
                                Data Analysis and  Display
Contouring  of  Lake Erie Water Quality Data by  Computer Graphics:   development of
      a computerized system  which can accurately construct a  large  number of
      illustrations of water quality and  biological data in a short period of time  at a
      relatively small cost...  in  addition, the system computes the areal extent of
      tne hypolimnion and  anoxic  zone,  the volume of hypolimnion, mesolimnion
      and epilimnion, the total heat and dissolved oxygen content or the concentration
      Of other  substance in the  thermal layers,  and  volume weighted averages  of
      any of these parameters ( a volume weighted average is  an average of the
      values which  is weighted according to the volume of water registering each
      value.
                                          10

-------
 sary precursors to  the  growth of plant  protoplasm.  These compounds
 are all  the organic  elements, but particularly:  (1) carbon, (2) oxygen,
 (3) nitrogen, and (4) phosphorus.  In addition to nutrients,  other con-
 trolling  factors are those found in the physical  category.  The physical
 parameters  measured are:  (1)  meteorological and lake  state conditions,
 (2) light penetration, (3) transmissibility, (4) pH,  (5) temperature, and
 (6) conductivity.  These data  were used to estimate  the  indirect effects
 on algal problems such as:   vertical  mixing, surface transfer coefficients,
 upwellings,  and dispersal of blooms;  and the direct  effects:   of  light
 penetration (photosynthesis),  temperature (community respiration), pH
 (state of chemical compounds and reactions)  and conductivity  (measure
 of dissolved  ions).  The forms  of nutrients examined in the study are:
 (1) bicarbonate  (alkalinity),  (2) soluble  reactive phosphorus,  (3)  total
 phosphorus,  (4) nitrate  + nitrite,  (5)  ammonia nitrogen (4 and 5 com-
 prise total dissolved inorganic nitrogen),  (6) particulate  organic  nitrogen,
 and (7)  particulate organic carbon.   The last two parameters  give an
 estimate of  the energy stored in the biomass.  Of particular interest
 are the  levels  of nitrogen and phosphorus present.   It is generally
 accepted that accelerated eutrophication and  increasing nitrogen  and
 phosphorus concentrations commonly proceed  together, and  that  in Lake
 Erie phosphorus is  the  limiting  factor in algal blooms,  particularly
 in the central basin.

      Detailed descriptions of  field methods used in this  study are con-
tained in the  "Procedures Manual" prepared  by  the Center for Lake
 Erie Area Research (1974) and submitted to  the Grosse  He  Laboratory,
 USEPA  as part of the  1973  Progress Report for Grant No. R-802543.
 In general, field procedures consisted of a series  of cruises  normally
 requiring about  ten days each.  The  ships were positioned by  compass
 and/or radar.   A typical cruise track was accomplished by making
 north-south transects; each leg required a full day to complete.   Sta-
tions were usually visited only during daylight hours.  On station, a
 bathythermograph (BT)  was used to determine the thermal structure  of
the lake.  If the lake was stratified,  samples were taken at four depths:
(1) one meter below the surface,  (2) one meter above the upper  "knee"
of the thermocline,  (3) one meter below the  lower "knee" of the thermo-
cline and (4) one meter above the bottom.   If the lake was  unstratified,
samples were only taken at  three depths: (1) one meter  below the  sur-
 face, (2) mid-water and (3)  one  meter above the bottom.  In  shallow
water, less  than seven meters,  only surface and bottom  samples were
taken (Figure 2).  Water samples were  taken with Niskin bottles in
 1973 and with a submersible  pump in 1974 and 1975.  Samples to be
 used for biological studies were taken with Niskin  bottles throughout
the study because of the danger  of mechanical damage to  planktonic cells
                                    11

-------
ro
                                10°
TEMPERATURE (°C)


  15°
                     JE  10 --
                     0.
                     UJ
                     Q
                        15 . .
                        20 • •
                                     Upper E"pilirnnion

                                        (Surface)
                                    Lower Epilimnion
            UNSTRATIFIED

            LAKE
                                                               SCHEMATIC REPRESENTATION OF
                                                               SAMPLING DEPTHS  IN LAKE  ERIE
                                   'STRATIFIED LAKE
                         Figure 2.   Schematic representation of  sampling depths in
                                      Lake Erie.

-------
passing through the pump.  The in  situ measurements (shipboard sen-
sors) were obtained by lowering submersible probes on a marked line
and taking readings at one-meter intervals from surface to bottom.

      Laboratory methods are also detailed  in the  "Procedures Manual"
produced  by CLEAR  (1974).   Shipboard and mainland laboratory  analy-
ses followed the procedures  in  "Standard Methods" of the  American
Public Health Association (1971) or the methods developed  by Technicon
and CCIW for AutoAnalyzers, elemental  analyzers, and spectrophoto-
meters.   Sedimentation techniques were used to concentrate phytoplank-
ton from  "whole water" samples.  Enumeration of these samples was
done  with  an inverted  microscope.  Zooplankton was sampled with verti-
cal tows with 20-mesh (80 microns) nets  fitted  with  inside and outside
flowmeters.   Identification was  done with a dissecting  microscope  and a
Ward counting  chamber.  Benthic macroinvertebrates were sampled with
a Ponar  dredge.  Sediment was sieved through a 40-mesh screen  and
the retained organisms were  identified with a dissecting  microscope.

      All  of the water  quality data from  the 1973,  1974 and 1975 cruises
have  been computerized and  olaced  in  EPA's STORET data system.
Dissolved  and suspended substances data from  lake samples  have been
analyzed by several techniques.   Most of the  parameters have been
plotted on charts and  contour maps constructed from  these values.
These maps provide  a useful  display of seasonal trends at various
depth horizons in the  two basins.  Another  technique  involved determin-
ing the volume-weighted mean concentration or  quantity of  a particular
parameter for  the  period  of  each cruise.   To obtain these values the
lake was  subdivided into "water quality grids"  (Figure 3) following
methods  developed for Project Hypo  (Burns and Ross,  1972 and Burns,
1976).  This orocedure assumes that a particular  station is  representa-
tive of the polyhedron  of surrounding  water.  The  concentration deter-
mined for each station  is extrapolated  to  total  volume  of water in  the
polyhedron.  A summation of all  of the polyhedrons within the basin
will yield  a total quantity of the parameter  under consideration.

SIGNIFICANT TRENDS

Dissolved Oxygen

      Dissolved  oxygen (DO)  concentrations in the western  basin of Lake
Erie  for 1973 and  1974 were  lowered to less than  6 ppm from June to
September during periods of temporary stratification.  In  each of
these  years, over 50  percent of the  basin experienced this condition.
                                   13

-------
        WATER QUALITY GRIDS USED FOR AREA- AND VOLUME-WEIGHTED CALCULATIONS IN
        THE CENTRAL AND WESTERN BASINS OF LAKE ERIE.
                                                          • MONITORING STATION
                                                          407
                                                           WATER QUALITY GRID
Figure  3.   Water quality  grids used  for  area- and volume-weighted
            calculations  In the central and western  basins  of Lake  Erie.

-------
 In June and August 1S73 tne DO level  tn the  mid and northeast sec-
 tions of the basin  was depleted to less than 1 ppm.   Depletion was
 not as severe  in 1974.   The lowest  concentrations were observed in
 Pioeon Bay (northeastern part  of basin)  during  July  and August where
 they did  not  fall below 3 ppm.

       The central basin of Lake  Erie,  because  of its middle latitude  and
 moderate  depth, stratifies into a relatively thick epilimnion (approxi-
 mately 15-20  meters) and  a thin hypolimnion  (approximately 3-5 meters).
 The  intervening mesolimnion (thermocline) has  a distinct temperature
 gradient  which limits mixing of dissolved substances between the other
 two layers.  As early as  1929,  Fish et  al. (1960) observed oxygen
 deficiencies in the hypolimnion.   Studies since  that  time (Carr, 1962;
 Beeton, 1963; Thomas,  1963;  FWPCA,  1968 a & b;  Herdendorf,  197O;'
 Dobson and Gilbertson,  1971;  Burns  and Ross,  1972) have shown a
 persistent  increase in magnitude of the deficiency and the area affected.
 Figure A illustrates the portion of the  hypolimnion that  has been  so
 depleted of oxygen as to become anoxic (less  than O.50  ppm) for selec-
 ted years between  1930  and 1974.  These maps  show a  progressive
 growth in the  anoxic area  of the central  basin from  less than  2 percent
 in 1930 to  nearly 7O percent in 1973.  Trends  in the anoxic area are
 given in Table 6.  By 1973 over 93  percent of  the hypolimnion had
 complete oxygen depletion.  Because the time of maximum extend of
 hypolimnetic anoxia varies considerably due to meteorological  conditions
 and because survey methods have improved through the  years,  these
 values should  only  be considered as  estimates based on  interpretations
 of historic  data.

      In 1974 the first depletion was  observed shortly after stratification
 and was most severe  in the southwestern section of  the  basin  where the
 lake  is less than 2O meters deep.  By late  July and early August con-
 centrations of less than  2 ppm  were  observed throughout the north-cen-
 tral part  of the  basin.   In  early  September nearly all of the central
 basin  bottom  water had less than  1 ppm.  After three months  of strati-
 fication, the lake cooled and overturned in mid-September resulting in
 dissolved oxygen levels above 6 ppm  throughout  the  basin.

      The level of DO in  the eastern  basin of  Lake Erie  did not
 suffer a serious depletion in 1973 or 1974.  However,  hypolimnion
 concentrations of less than  6  ppm were observed for each  month
 during the period July to November,  less than 5 ppm for Auaust
to October and  less than 4  ppm in August 1974  and September 1973.
 In 1973 the greatest areal extent  of low DO  « 6 ppm) occurred in
 mid-September and early October in  the  western and central sections
                                 15

-------
Figure 4.  Trends  in anoxic hypolimnion of Lake  Erie 1930-1974.

-------
  TABLE 6.   ESTIMATED AREA OF THE ANOXIC HYPOLIMNION OF
           THE CENTRAL BASIN OF LAKE ERIE 1930-1974
YEAR
1930
1959
1960
1961
1964
1967
1970
1972
1973
1974
1975
AREA
(km2)
300
3,6OO
1,660
3,640
5,870
7,500
6,600
7,970
1 1 , 270
10,250
400
PERCENT OF CENTRAL BASIN
Hypolimnion
3.0
33.0
15.0
33.0
53.0
68.0
60.0
72.5
93.7
87.0
3.4
Total
1 .9
22.3
10. 3
22.5
36.3
46.4
40.4
49.3
69.8
63.4
2.5
Data Sources:
     193O - Fish (196O)
     1959-61 - Thomas (1963)
     1964 - FWPCA (1968a)
     1967 - Herdendorf (1970)
     197O - Burns  and Ross (1972)
     1972-75 - CLEAR
                                  17

-------
of the eastern basin.   Whereas, in 1974 the greatest area of low levels
«6 ppm) was found in the eastern half of the basin during mid-August
and early  September (Robert Sweeney,  Great Lakes Laboratory,  per-
sonal communication).

      During thermal stratification in each basin the DO content of the
hypolimnion experienced a marked decline.   The oxygen deficit that
takes place between thermocline formation is a rather complex set
of mechanisms.   The major components of these  processes include:

      1 .   Internal oxygen depletion within the hypolimnion due to
          bacterial oxidation of organic material and the oxidation
          of reduced metallic species (Burns  and  Ross,  1972),  in-
          cluding  oxygen consumption at the sediment water intei—
          face;

      2.   Volumetric changes in the  hypolimnion caused  by the loss
          or gain of water,  including dissolved  oxygen, to or from
          the  overlying  mesolimnion;

      3.   Exchange  of water between the mesolimnion  and hypo-
          limnion including  dissolved oxygen,  without volumetric
          changes in either strata;

      4.   Entrainment of adjacent basin and tributary water masses
          within the hypolimnion, including dissolved oxygen.

      Because stratification is so temporary in  the  western basin,
adequate measurements of the oxygen deficit were not possible.   Carr
et al  (1965), estimated  that  in 1963 only five days of stratification were
required to reduce hypolimnion dissolved oxygen to 3 ppm in  this basin,
whereas,  28 days were needed  in 1953.   Near zero oxygen levels were
observed  in June  1973  after several  days of calm weather which  indi-
cates that oxygen demand of the bottom sediments continues to be very
high.

      Trends in the net oxygen  demand  for the central and eastern basins
are presented in Table  7.  In the hypolimnion,  the oxygen concentration
in the central basin was reduced approximately 0.1 ppm per day  in
1974; whereas,  in the deeper eastern basin, the loss rate was only 0.01
ppm per day.  This rate represents a doubling of the net oxygen  demand
since 1930 (Table 7).  A slight reduction in the demand rate  has  been
noted in  the past  five years which may be related to reduced pollution
loads and  high water conditions.
                                   18

-------
TABLE 7.  TRENDS IN NET OXYGEN DEMAND OF THE CENTRAL
      AND EASTERN BASIN HYPOLIMNIONS OF LAKE  ERIE
YEAR

1930
1940
1950
1960
1970
1973
1974
1975
NET OXYGEN DEMAND
Rate Per Unit Area
(mg OQ cm day"1)
Central
Basin
0.008
0.015
0.025
0.037
0.039
0.053
0.060
0.067
Eastern
Basin
-
-
-
-
-
0.023
O.C95
0.076
Rate Per Unit Volume
(mg O2 I day )
Central
Basin
0.054
0.067
0.070
0.093
0.13
0.12
0.13
0.10
Eastern
Basin
-
-
-
-
-
0.012
0 .040
O.O40
 Data  Sources:
      1930-70 - Dobson  and  Gilbertson (1971)
      1973-75 - CLEAR  and GLL
                                 19

-------
      The anoxic conditions which now annually  exist  in the central basin
have  impaired the  usefulness of the  lake.   Cold water fish,  such as
whitefish and lake  herring, once over-summered  in the cold bottom
water.   These species have  been extirpated due to the lack of oxygen
in the hypolimnion.   Likewise,  the  diverse macroinvertebrate  fauna  of
the bottom has  been reduced to oligochaete worms and chironomid lar-
vae.   Upwelling of anoxic  water at  times causes  discoloration of sur-
face water along the  Ontario shoreline and  taste and  odor problems  in
drinking water supply along the Ohio shoreline.   A more subtle  problem
associated with anoxic conditions is  the regeneration  of nutrients,  par-
ticularly soluble phosphorus.  As the DO concentration  approached
zero (0.25 ppm), a sharp  increase  was observed in the level of soluble
phosphorus; and  at  0.10  ppm, DO regeneration  of sedimented phosphorus
resulted in levels over  10  times the normal background concentration
for oxic conditions  (Figures  5 and 6).  This process  provides a recy-
cling  of phosphorus in the  lake  system and may result in excessive
algal  production.

      In 1975, a dramatic  change in this situation appears to have taken
place.  Although a  significant amount of oxygen depletion did occur, only
a relatively small  portion  of the basin experienced complete anoxia
(approximately 40O  km2).  Equally  important as the  improvement in
DO concentrations  was the significant decline in regenerated phosphorus
from  the bottom sediments as a result of  maintaining an  oxic  zone at
the sediment/water interface throughout most of the basin (Tables 6
and 7).

      The reason for  this  major shift in the oxygen regime of the hypo-
limnion  is not immediately apparent.  Reductions  in nutrient  loadings
would  be expected  to  produce a more gradual improvement,  not the
dramatic situation  observed  in a single year.   An analysis of meteoro-
logical conditions and resultant  water circulation  phenomena provide
some basis for an  explanation.

      Six cruises were  conducted in the  western and  central basins of
Lake  Erie between  March  and  December 1975.   Dissolved oxygen  con-
centrations were measured at one-meter intervals at  51  stations during
each cruise.   In March  and  April the lake  was nearly isothermal  and
all  DO levels were between  12-14 ppm.   By mid-June the central basin
had stratified and slight DO  depressions were noted  in Ohio waters
north of Ashtabula  and Huron.  In mid-July this depression deepened
on the American side of the lake,  while the Canadian side continued to
enjoy relatively high  DO levels.  At this time,  an extensive area  with
less than 4 ppm DO persisted within a thin portion of the hypolimnion
                                    20

-------
                                   !QNSHi|P!&ETVyEEN
                                       LOVVER
R/LAKE
REGENERA
      15
Figure 5.  Relationship between dissolved oxygen  concentrations in the lower hypo-
           limnlon of central Lake Erie and soluble  reactive phosphorus regenera-
           tion,  Cruises 7 and  8  - August  12-September  5,  1974.

-------
 PPB     PPM
(M9/1)    (mg/l)

   15 -r 15
00

o;
O
Q_

O
a.
LU
>
h-
O

o:
   10 -• 10
5-- 5
          o
          X
          O
          O
          oo
                            Soluble Phosphorus
                    Dissolved
                     Oxygen
CO
=)
I
O 0 -



\ /
\ /
• 0




CM
LU
00
O
i




APR ' MAY

^.
LU
o:
o





in
LU
00
s
O
i





(D
LU
00
I
O
t





^
LU
o:
o




•
CO
LU
00
a
o
•





o
LU
00
cr
o
JUNE ' JULY ' AUG ' SEPT ' OCT '
                           OBSERVATION DATES
Figure 6.   Concentration  of soluble reactive phosphorus
             and dissolved  oxygen  in the  central basin
             hypolimnion  of Lake Erie -  1974.
                               22

-------
off the Ohio shore.  In late  August and early September  the  maximum
oxygen depletion occurred  and resulted  in the formation of an anoxic
zone 50  km  long and 8 km wide offshore  between Cleveland and Huron,
Ohio (Figure 7).   At this time  the zone of  water with less  than 4 ppm
DO occupied a more central part of the lake,  flanked  by  more oxygena-
ted water east of Cleveland  and on the  Canadian side of the lake.  The
nearshore  portions of  the  lake had overturned  by late  September and
early October  dissipating the anoxic zone  and leaving only a  small  zone
of oxygen depression near the center of the basin  where  the  lake
remained stratified.   In December the lake was again nearly isothermal
with high DO levels.   No  serious oxygen  depression was  noted in the
western  basin  throughout the year  with  the  exception of a small area
southeast of the islands which experienced DO levels below 4 ppm in July.

      Changes  in the configuration  of the hypolimnion during 1975 were
similar to those of 1973 and 1974.   The characteristics of the central
basin hypolimnion  for  these  years  are compared in Table 8.   The  volu-
metric oxygen demand rates  for all three years were similar with a slight
decrease in 1975,  whereas the area  rate showed an increase in 1975. This  is
probably related to the  increased thickness of the hypolimnion  in 1975. With
more water  depleting at nearly the same  volumetric rate, a  higher
depletion rate  per unit area  of  the bottom would be expected.  The in-
creased  thickness  in 1975  apparently provided  a larger reservoir of
DO which was able to  withstand the  depletion rate without becoming
completely anoxic.

Meteorological Conditions

     A major change  in the oxygen  demand rate within the hypolimnion
can be discounted as the reason for the improvement in the DO  content
of that layer.   However, a comparison of hypolimnetic conditions for
1973, 1974  and 1975 provides some  insight to  this problem (Table  8).
Compared  with  earlier  years, from  the onset the 1975 hypolimnion
was thicker  and contained  a  higher dissolved oxygen concentration.
This situation  persisted throughout the period of stratification.   Appar-
ently there  was enough oxygen in the initial reservoir to  satisfy the
demand without depleting the hypolimnetic supply before the fall turn-
over replenished oxygen to the  bottom.

     The most plausible explanation for the thick  hypolimnion involves
the meteorological conditions at the  time  of thermocline  formation.
Monthly  air  temperatures and wind recording at Toledo,  Ohio indicate
that in 1973  and 1974 the warming from April  to May was approximately
                                   23

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PO
                                                                        BOTTOM DISSOLVED OXYGEN
                                                                      CRUISE 4 AUG 27 - SEPT 7,  1975
                                                                          Contour Interval:  1  ppm
             Figure 7.  Bottom dissolved  oxygen,  cruise 4, August 27-September 7,  1975.

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                TABLE 8.  COMPARISON OF 1973, 1974 AND  1975 CHARACTERISTICS

                             OF  HYPOLIMNION IN  CENTRAL LAKE  ERIE
ro
en
YEAR
1970
(Projec
1973
1974
1975
JUNE
Thick
(m)
_
Hypo
-
6.2
6.9
DO
(ppm)
_
)
-
9.9
10.1
Temp
C°C)
_

-
8.8
7.4
JULY
Thick
(m)


5.0
4.6
5.7
DO
(ppm)
.

4.9
5.2
7.5
Temp
C°C)
.

10.3
11.8
9.0
AUGUST
Thick
(m)
_

4.4
4.3
5.8
DO
(ppm)
_

1.6
2.1
3.5
Temp
(°C)
_

11.9
13.5
10.5
SEPTEMBER
Thick
(m)
„

3.0
-
3.0
DO
(ppm)


1.1
-
4.3
Temp
(°C)
.

13.8
-
14.5
NET OXYGEN DEMAND
loss/day
(mg O2/cm )
Rate per
unit area
0.039

0.053
0.060
O.067
loss/day
(mg 02/l )
Rate per
unit
volume
0.13

0.12
0.13
0.10

-------
3.9°C,  whereas  in  1975 the  air temperature increased  11.1°C during
the same period.  During the spring months the wind speeds were con-
siderably lower  in 1975  at Long  Point,  Ont. (Figure 8).  It appears
that a calm,  rapidly warming spring can cause the thermocline to be
fixed higher in the water column yielding a thicker hypolimnion.  It was
initially  suspected that storms throughout the summer period resulted  in
the entrainment  of warmer,  oxygen-rich water from the upper layers.
However, the warming of the hypolimnion was not significantly different
in the three years under consideration, with the exception of September
1975  when it  occurred in conjunction with the fall  turnover, which has
been  discussed earlier.  Average monthly wind speeds  for  June to
September at Toledo  were within  one mile  per  hour for 1974 and 1975.
This  further substantiates the fact that  increased entrainment did not
occur as a  result of unusual summer wind  velocities  in 1975.

      The present  information leads to the conclusion that spring  wea-
ther conditions can greatly influence the thermal structure  of Lake  Erie
and thereby affect the degree of oxygen depletion which takes place in
the central  basin.   A much more detailed inspection of meteorological
data throughout the Lake Erie basin should be undertaken to verify
these effects.
Nutrient Chemistry

      The distribution patterns exhibited  by all of the monitored nutrients
were  basically similar.  Western basin  concentrations nearly always
exceeded  those of  the central basin.  The western and southern near-
shore areas  of the western basin,  specifically the vicinity of Monroe,
Michigan  and Toledo, Ohio,  routinely exhibited  the highest concentrations.
This area is subject to the greatest loading  from both municipal/indus-
trial point sources and  from land runoff non-point sources.

      The Detroit River represents the  most significant  single  source
of nutrient loading to Lake Erie, largely because it contributes over
90 percent of the water input to the lake.  However, the concentration
of nutrients  entering the lake is frequently lower than at those found
within the basin; thus,  distributional maps often show low contour
values near  the Detroit River mouth.

      The central basin showed  a somewhat similar pattern in that  a
distinct south to north gradient  of  decreasing concentration  was evident
for most  nutrients.  The Ohio nearshore region is subject to the highest
                                    26

-------
sw
WIND
SPEED
(MPH)
0-10
10-20
>20
WIND DIRECTION (% time)
N
0.0
0.0
0.0
NE
2.2
12.1
4 .4
E
4.4
4.4
0.0
SE
1 .1
1 . 1
O.O
s
4.4
6.7
2.2
SW
13.3
24.4
2.2
W
4.4
7.8
1 .1
NW
0.0
2.2
l . '
                                20%
         SW
                              SE
                  1975
   •V      '  O - 10 mph
   """""""T  10 - 2O mph
             2O  mph
                                                     1974
                                                    1975
O-10
10-20
>20
1 .1
0.0
0.0
2.2
7.8
4.4
2.2
3.3
0.0
O.O
3.3
1 .1
7.8
7.8
2.2
6.7
25.5
8.9
7.8
3.3
1 .1
3.3
0.0
0.0
0-1O
10-20
>20
2.2
1 .1
O.O
6.7
5.6
2.2
7.8
5.6
O.O
2.2
O.O
0.0
5.6
3.3
1 .1
5.6
14.4
2.2
11.1
7.8
1 . 1
7.8
3.3
4.4
   Figure 8 .  Daily resultant wind  at  Long Point,  Ontario
               for April, May and June  1973-1975.
                                  27

-------
loading  in  the central basin from both point and non-point sources.
In addition, nutrient-rich water entering the central basin from  the
western basin tends to be  largely confined to the southern shore.   A
distinct west to east gradient of decreasing  nutrient concentrations
was  also observed.  The section of  the central basin joining the
western basin near the  mouth of Sandusky Bay (Sandusky sub-basin)
typically has high  nutrient concentration during the summer  months.
In early to mid-August  anoxic  conditions develop  first in this  shallow
area because of the thinness of the hypolimnion,  thus  releasing  sedi-
mented  nutrients (anoxic regeneration).

      The  vertical  distribution  patterns were similar for most nutrients.
This western basin is typically isothermal from surface to bottom
throughout most of the year.   This  is particularly true  during periods
of high  winds (winter,  spring and fall).  In  summer, calm periods
permit ephemeral  thermal stratification to develop,  resulting  in non-
homogeneous vertical distribution of nutrients.   The nutrients which
are concentrated in the bottom  waters due to bacterial decomposition
and/or brief anoxic conditions  in summer  are quickly redistributed by
wind and wave action in this shallow basin.

      The  central basin, like the western basin,  is vertically homogene-
ous during non-stratified  periods.   For approximately 10O days  from
June to September the central basin  is thermally stratified.   At the
onset of stratification the epilimnion  and hypolimnion are very similar
in chemical composition, however,  as summer progresses these layers
become increasingly dissimilar.  In general, there  is a net increase
of nutrients in the hypolimnion  as  a result of settling and decomposi-
tion  of plankton.   In late August and early September, anoxic conditions
prevailed  in the hypolimnion.  The change  from oxidizing to reducing
conditions  in the hypolimnion resulted in release  of phosphorus (con-
centrations of soluble reactive phosphorus increase up to twenty-fold),
ammonia and silica.

      Phosphorus  budget.  Nutrient budgets  provide a basis  for
quantitatively assessing the net transfer of materials between  various
compartments of Lake Erie.  Measurements of total phosphorus during
the period  1970-75 (Figures 9 and 10) were used to calculate budgets for the
western  and central  basins of  Lake  Erie (Table 9).   Although the exter-
nal loading of phosphorus to these basins has  decreased slightly during
this  period (12%-western basin;  13%-central basin),  the  quantity and
concentration of  phosphorus  have remained more stable  (slight rise
in the western basin and slight decrease  in the central basin).  Approxi-
mately  82  percent of the combined  external  loading  was retained within
the basins  in the form of sedimented phosphorus.  The  western and  cen-
tral  basin  thereby serve as  effective sinks for phosphorus.

                                   28

-------
IN3
10
ITY OF PHO
    000


    000


    000


    000


    000


    000


    000


    000
«">  3,000


£  2,000


   1,000
                                                                      Data Sources:

                                                                      1970-72 Canada Centre for Inlands Waters
                                                                      1973-75 Center for Lake Erie Area Research
                                                                            Ohio State University
                   V
                                       Western Basin

                                                         5t7*F
                                                                     JJ ASONDIJ  F M A M J J ASONDIJ F' M'A'M'
                                                                     1972                    1973
                                                                                                            J  J  A
                                                                                                            1974
                                                                                                                 'S'O'N 'D| J'F'M A
MJJASOND'
  1975
                                                             DATE OF  OBSERVATION
                             Figure  9.    Quantity of  phosphorus  In  Lake  Erie,   1970-1975.

-------
-O
s
8
O
                               Western Basin
l/"\l      A   \
                             \    \
            V
                                          Central Basin •
                                                            Data Sources:

                                                            197O-72  Canada Centre for Inland Waters
                                                            1973-75  Center for Lake Erie Area Research

                                                                  Ohio State University
                                                          1972

                                                 DATE OF  OBSERVATION
                                                                               j j
                                                                               1973
                                                                                  M'A'M'J 'i 'A'S 'o "N'D|J  F'M A M'J j 'A'S 'o 'N 'D|
                                                                                       1974                  1975
                Figure  10.   Total  phosphorus  concentrations  in  Lake  Erie,  1970-1975.

-------
        TABLE 9.   PHOSPHORUS BUDGET  FOR THE WESTERN AND CENTRAL
                 BASINS OF LAKE ERIE, MAY-SEPTEMBER  1970-1975
Year
1970
1973
1974
1975
WESTERN BASIN
External Loading
(m tons per year)
17,000
17,500
16,600
.14,900
Mean Quantity
(m tons)
900
810*
840
980
Mean Concentration
Oug/l)
38.3
34.6*
35.4
41 .8
Retained Loading
(%)
61
62*
59
53
Year
1970
1973
1974
1975
CENTRAL BASIN
External
Loading
(m tons)
4,500
4,000
4,200
3,900
W.B.
Loading
(m tons)
6,600
6,650
6,800
7,000
Mean
Quantity
(m tons)
5,500
5,450*
5,250
5,150
Mean
Cone.
()jg/l)
17.9
17.5*
16.6
17.0
Retained
Loading
69
71*
67
63
Anoxic
Regeneration
(m tons)
1900
2570
1720
730
 * Estimated  from partial data
Data Sources:
    1970 - CCIW
1973-75 - CLEAR    External loading-U.S. Army,  Corps of Engineers

-------
      The  area of anoxia  varied greatly during the study period/  how-
ever,  the  quantities  of total phosphorus in the central basin were not
significantly different.  For 1973, 1974 and  1975 anoxic regeneration
in the western  and central  basins amounted to only 13.5, 8.2  and 4.0
percent of the combined external loading,  respectively.  The small
percentage for  1975  (730  metric tons) is  in response to the small area
of anoxia observed that year.   However,  the  central  basin  phosphorus
budget for 1975 (Table 10)  shows that 8 percent of the total phosphorus
loading (internal plus external)  is attributed to anoxic regeneration and
30 percent to oxic or physical regeneration (sediment resuspension).
Physical regeneration, generally associated with winter and spring
storms,  appears  to be the  major source  of internal  phosphorus load-
ing,  whereas anoxic  regeneration may be considered  of secondary
importance except for a  short period of time in late  summer.

      Total phosphorus (TP).   This parameter is considered useful in
identifying areas  of high nutrient concentrations  and  biological produc-
tion.   As  with  other nutrients monitored,  some  distinct distribution
patterns  were  evident.  Areas of high phosphorus  loading generally pro-
duce productive regions where the nutrient-rich  tributary waters  mix with
the lake.   This situation  existed along the western and southern shores
of the central  basin  from Sandusky to Ashtabula Harbor.  A decreasing
west to east concentration gradient  was found to be evident for TP and
many other parameters monitored.   Three major zones of  decreasing
concentrations could  be distinguished: (1)  western basin having the high-
est concentration, (2) western central basin,  extending  east from a
north-south line between  Rondeau  Harbor to  just west of Cleveland
having intermediate concentration and (3)  eastern central basin,  extend-
ing eastward to the division between the central and the eastern basin
having the lowest concentration.

      The yearly  variation in quantities of TP in the  western basin
were  not nearly as great as the fluctuations  in  the central  basin  due to
the relatively smaller volume of the western  basin (Figures 11 and 12).
The concentrations of TP in the western  basin fluctuate greatly through-
out the year.   Initial spring concentrations are high as a result of
loading from the  tributaries entering  the  western basin, the vernal dia-
tom pulse  and resuspended  sediments.  The  spring high was followed
by a decrease during the early summer.   This is due to a reduction
in loading  and settling of previously resuspended sediments.   During
the summer the concentration can fluctuate rapidly due to high winds
resuspending sediments or  the development of anoxic  conditions.   In
1974 anoxic conditions did develop in late August resulting  in an  increase
                                   32

-------
 TABLE 10.  CONCENTRATION AND QUANTITY OF TOTAL
PHOSPHORUS IN WESTERN AND CENTRAL  LAKE ERIE  -  1975
Basin
Cruise No. 1 (A
Western
Central
Cruise No . 2 (^
Westerr,
Central
Epilimnion
Mesolimnion
Hypolimnion
Total Basin
Cruise No. 3 (.
Western
Central
Epilimnion
Mesolimnion
Hypolimnion
Total Basin
Cruise No. 4 (/^
Western
Central
Epilimnion
Mesolimnion
Hypolimnion
Total Basin
Cruise No. 5 (S<
Western
Central
Cruise No. 6. (C
Western
Central
Concentration
Cug/l)
/larch 27 - April
56.61
23.00
une 6-19)
32.35
13.91
15.66
15.65
14.63
July 13-21)
46.48
12.73
17.85
21 .19
15.80
August 30 - Septe
38.24
15.34
14.17
17.91
15.83
sptember 9 - Oct
43.24
19.98
)ecember 2-14)
37.04
31 .66
Quantity
(metric tons)
25)
1338.33
7100.86
760 . 1 5
2421 .42
469.27
1638.34
4529.03
1085.42
2325.01
634.71
1917.11
4876.83
mber 5)
892.88
3488.53
215.86
1183.63
4888.02
ober 6)
997.44
6134.24
834.90
9623.04
Lake Volume
(km2)
23.64
308 . 79
23.50
174.03
29.96
104.70
309.49
23.35
182.64
35.56
90.49
308.69
23.35
227.39
15.23
66.07
308.69
23.07
307.06
22.54
303.96
                               33

-------
S          §          §           3          S
TOTAL. PHOSPHORUS CONCENTRATION QJG/L.)
IX)
0)

0)
  A
Q)
T
LJ
0)
                                                                   c
                                                                   o
                                                                  0)
                                                                  o
                                                                  o
                                                                  o
                                                                  w
                                                                  o
                                                                  a
                                                                  w
                                                                  (
                                                                  0)
                                                                  O)
                                                                                                                                                             IO
                                                                                                                                                             N
                                                                                                                                                             0)
                                                                                             TOTAL PHOSPHORUS QUANTITY (METRIC TONS)
                                                                                           0)
                                                                                           3
                                                                                           O)
                                                                                                        ro

-------
in phosphorus.   A peak  in  TP also occurred in  July  1975, following
a period of high winds.   Autumn was a  period of  increased quantities
of phosphorus  in the central basin; however, the western  basin  levels
decreased  both  in  quantity and quality compared with spring values.

      Spring concentrations and  total  tons  of TP in the central basin
were high  throughout the lake.   This was  due to the  resuspension of
previously settled  inorganic and organic sediment and the high concentra-
tions and quantities of phosphorus contributed by the tributaries. During the
nonstratified periods of the season,  seston-bound phosphorus contri-
buted a  large portion to the TP.  Following stratification  in late May
or early June,  much of  the resuspended materials from the sediments
settled.  In the central basin the vernal phytoplankton pulse ceased and
the cells continued to settle through the early summer; consequently,
surface  TP was reduced while hypolimnion concentrations  increased.
The  TP  continued  to decrease until August when phytoplankton growth
increased  in the central  basin.   Surface values  of TP  increased dur-
ing the late summer, possibly influenced by four sources: (1)  nutrient-
rich hypolimnion water  mixed with  the epilimnion, (2) western basin
inputs into the epilimnion of the central basin,  (3) point and non-point
sources  primarily  along  the southern shore  and  (4) sediment regeneration
of TP in unstratified water of the central  basin.

      Bottom waters  of  the  central  basin during  1973 and  1974 greatly
increased  in concentration of TP during August.  This was  due  to  exten-
sive anoxic hypolimnion  regeneration  of  soluble reactive phosphorus (SRP)
in the central basin.  During 1975  no large increase of TP was found in
the hypolimnion coinciding with limited development  of anoxia  in the  ba-
sin.   Following turnover in  1974,  TP remained  constant.   The  period
after turnover was not greatly affected by resuspension of bottom ma-
terials,  and  TP values  remained constant.  The 1973 and 1975  post-
turnover cruises demonstrated a different  trend.   Only a  small  increase
occurred just following  turnover in 1975,  but by December the quantity
of TP had nearly doubled (Figure  13).   This dramatic increase  may be
attributed to large quantities  of  resuspended organic  and  inorganic  sedi-
mented materials during the late fall.

      Soluble  reactive phosphorus (SRP) .   Trends in the   1974-1975
quantities and concentrations of  SRP  in  the  western  and central  basin
of Lake  Erie  are depicted in  Figures 14 and 15.   The western basin
quantities of SRP  were  relatively stable during this  period compared to
the central basin;  however, the  concentrations varied more  widely.
Spring concentrations in the western  basin remained  high  due to the
extensive loading from the tributaries  during that time of  year.   Fol-
lowing the  reduction  in flow from the rivers entering the  western basin,
                                   35

-------
SOOO T
80OO -
7OOO . .
6OOO- .
SOOO
4OOO .
SOOO .
2OOO-
1OOO .
D
I
               Central Basin
               Western Basin
  n
n
     ii  ii  iiii   i  i	1  ill—i	•—'  i  i	;—i   ,	,  i  ,
     JFMAM  JJA iS O  ND JFMAM  J  JASOND
                1974
                                           1975
 Figure  13.  Volume weighted quantity (metric tons) of
              total phosphorus  In  Lake  Erie,  1974-1975.
                              36

-------
     18- .
     -t
   3
   z
              Western Basin
               Central Basin
                                             'j ' j 'A'S'O ' N' o
                                              1975
                        TTT"
                         1974
Figure 14.   Soluble reactive  phosphorus  concentrations

              in Lake Erie,  1974-1975.
b

n
n
2  1500
H
~
>
H

5
2

I

i
Ul
              Central Basin
             Western Basin
      J I ATS 'O' N >O\J 'F'M'A. 'M^.!1 J TA1S1 O'N'OIJ 'F 'M'A'M'j TJ ' A' S1 O'N" 31
          1973    '        1974                   1975

                             DATE



Figure 15.   Soluble reactive phosphorus quantity  in


              Lake Erie, 1974-1975.
                            37

-------
the fluctuations in concentrations are largely due to internal  processes.
Large decreases  in  SRP are generally associated with an increase in
chlorophyll a. and vice versa.   Anoxic conditions do exist in  the western
basin for short periods,  and as in  the  central basin,  SRP is released
under these conditions adding to the extreme fluctuations that occur in
the basin.

      Following the spring pulse of phytoplankton in the  central basin,
the SRP  increased  and through the later portion  of the summer there
was an accumulation of  SRP in the central basin hypolimnion water.
During  this period in 1974,  the concentration of SRP  in the hypolimnion
increased  from 3 jug/I to over  15 wg/l,  while the tonnage went from less
than 200  metric tons (mt) to more  than  700 mt.  This increase can be
attributed  to anoxic  regeneration of SRP from the  sediments  in the cen-
tral basin.  During the  same period a  slight increase of SRP  in the sur-
face waters occurred.   This increase  was  largely  due to the exchange
of phosphorus  rich  hypolimnion water into the epilimnion.  Following
turnover  phytoplankton growth  increased and uptake of SRP increased.
This, as well as settling of plankton and inorganically bound SRR, ac-
counted for the fall depletion.   In 1975 the greatest change occurred
in the late  fall when the concentration in the central  basin increased
from 2.5 Xjg/l  to greater than 8 ;ug/l  and the tonnage increased from
800 mt to 2500 mt.   This increase was substantially greater than the
increase  in 1974, which was attributed  to anoxic regeneration.  During
ice-free conditions  in the late fall and  winter, the  lake  is subject to
periods of high winds which readily resuspend bottom sediments.  This
turbulent action released large  quantities of SRP from the sediments
and interstitial water.

      Nitrate plus nitrite.  The highest concentrations of nitrate plus
nitrite were found during the spring cruises.  Vertical distribution
was essentially uniform  in both basins.   The concentrations along the
south shore indicated major sources of river inputs both in the western
and central basins.  The Detroit River flow was characterized by lower
concentrations  than the other river mouths.  The entire north shore
and mid-lake concentrations were significantly lower  than those of the
western basin  and south shore of the  central basin.  By  June, concen-
trations were greatly diminished due to  a reduction of loading from the
tributaries.  The same  general pattern as  found  in the early spring
prevailed with  the highest concentrations found along  the  south  shore  in
both the western and central basins.   Mid-lake and north shore concen-
trations were distinctly  lower than  those of the south shore.   During
July a slight decrease was evident  in the western basin probably due
to algal uptake.   Distinctly higher concentrations were found  near the
western basin  shorelines, primarily near the mouth of the Maumee
                                   38

-------
River.   The south shore  of the central basin remained higher than
the mid-lake or  north shore,  and a  slight increase in hypolimnion
concentrations  became evident.   During August, surface concentrations
of nitrate plus nitrite  were markedly reduced due to  possible  algal
uptake and  losses to sediments or hypolimnion  waters.  Hypolimnion
concentrations  increased  in July;  however,  a decrease  was evident in
August.   This  was likely due to the conversion of nitrate  and nitrite
to ammonia during the development of anoxic conditions.   Following
turnover, concentrations  were further depleted  possibly due to bio-
logical uptake.

      Ammonia.   In  spring,  concentrations  of ammonia were uniform
throughout the  water column.   Highest concentrations were found in the
western  basin  primarily to the  west and south of Pelee Island.   The
central  basin exhibited two distinct regions-the northern half containing
relatively low  concentrations  and  southern half  containing  relatively
high concentrations.    The high  concentrations found  in  the western basin
and southern central basin were primarily  due  to  high  river  inputs dur-
ing the  spring  and wind-resuspended  bottom materials.

      Summer  ammonia  concentrations at the surface were reduced
appreciably in  both basins.   This period  coincides with an increase
of biological activity.   Bottom concentrations were greater than sur-
face concentrations in both basins as a result of decomposition of
spring and  summer plankton.  Concentrations were highest near  the
Maumee Bay and the south shore of the central basin.   During mid
to late August bottom  concentrations  of ammonia remained high in both
basins.    Prior to  anoxia,  ammonia  concentrations continued  to  increase
in the hypolimnion of  the central  basin as a result of decomposition of
phytoplankton settling  from surface waters.   Following anoxia,  ammonia
was thought to be  liberated from  interstitial water into the hypolimnion.
Consequently,  very high concentrations of ammonia were  recorded  in
the anoxic  regions.   After turnover,  surface concentrations in both
basins were uniformly low.   Chlorophyll  a_ levels  were high through-
out the  lake,  thus the low ammonia values could be attributed to algal
uptake.    Bottom concentrations remained higher than surface  concentra-
tions through the early fall.

      Total  inorganic nitrogen.   The  seasonal trends and  quantities of
total  dissolved inorganic  nitrogen are similar to those  of  nitrate  plus
nitrite.    Nitrate plus  nitrite  generally contributed 80 to 90 percent of
the total  inorganic nitrogen; thus, the fluctuations were essentially the
same.   Concentrations and tonnages were greatest in the  spring.
Spring western basin  concentrations were nearly 2.5 times greater
                                   39

-------
than those found  in the central basin.   The  contribution of total
inorganic nitrogen from the tributaries was  highest  in quantity as well
as  concentration  during the  late winter and  early spring.   The tribu-
tary contributions accounted for the high  values recorded  in both
basins early  in the year.

      Concentrations and tonnages  were reduced over the summer
months.   By  the  end of the summer,  yearly values  for  each basin
were reduced to  nearly the  same  level.   The quantities of nitrate and
nitrite in the hypolimnton dropped during  the first portion of the summer,
The hypolimnion  concentrations rose during  mid-summer,  but decreased
at the height  of anoxia.   Conversion of nitrate to ammonia during this
period may have  accounted  for a portion  of  the  decrease.

      Following turnover, nitrate plus  nitrite continued to  decrease.
However, the December 1975  cruise showed an  increase in  the concen-
tration of total  dissolved  inorganic nitrogen.   The increase  was pai—
ticularly dramatic in the  central basin where the quantity  rose more
than 1500 tons.   This increase during late  fall may  be a result of
nitrification and  increased flow from the  tributaries.

      Soluble reactive silica (SRS).  During early spring  the  western
basin concentrations of SRS were the  highest encountered.  Concentra-
tions were uniform from  surface to bottom  throughout most of the
western  basin.  A pronounced decreasing concentration gradient was
evident from  the  western part of the basin  into  the central basin.
The highest concentrations  encountered were found along the south shore
near Maumee Bay.  The  central basin was  nearly vertically and  hori-
zontally  homogeneous at this time.

      By May, western basin concentrations  were greatly reduced as
a result  of the reduction  of tributary loading.  Other factors contributing
to the  reduction in the  western basin were assimilation  by diatoms,
movement of the SRS-rich water mass into the central  basin,  and sedi-
mentation in the western  basin.   From May to June, western  basin
concentrations increased threefold.  This  was most  evident along the
northern and  southern shorelines.   By June, concentrations  had returned
to levels encountered during April.  High concentrations were found
along the western shore near the Raisin River  during this period.

     Central  basin concentrations  increased during spring, particularly
in the  hypolimnion.  Surface concentrations  were lower  than bottom
concentrations due to diatom assimilation  and net losses to the hypo-
limnion.   The south  shore  exhibited the highest concentrations  in the
                                   40

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central basin.  During  the  remainder of the stratified season  the
surface concentrations  remained nearly stable, and the bottom con-
centrations increased steadily reaching  the highest  concentrations dur-
ing August.   In the southwest half of the central basin,  primarily near
the Cuyahoga River, the hypolimnion concentrations were higher than
any other  region  within the basin.

      Following turnover, concentrations again increased  throughout
the western  basin and  remained at the  same concentration  into Decem-
ber.   The central basin became vertically  homogeneous  by late Septem-
ber with areas of low  concentration  in  the  northern and  eastern sec-
tions  of the  basin.

      Particulate  organic  carbon (POC)  and nitrogen (PON).  In spring,
the vertical  distribution of  POC was nearly uniform throughout the
western and central  basins.  Concentrations in the western basin were
significantly greater than those observed  in the  central basin.  This
was due to loading and resuspension particularly in the shallow regions
and the development of the  phytoplankton  community in the  northern
and western portion  of  the  basin.  The mid-portion of the  central basin
exhibited the lowest  concentrations,  while along  the south shore signifi-
cantly greater values were  recorded corresponding to  the areas of
highest chlorophyll a concentrations in the central basin.

      Concentrations in the  western basin  increased by June accompanied
by an  increase in chlorophyll a^ principally in the  western half of the
basin.  Mid-lake  central  basin surface  concentrations  decreased between
cruises in late spring  due to settling.  After the onset of stratification
in the central basin, resuspension of POC  was only significant in
unstratified areas.

      Throughout  the summer,  POC  concentrations  remained high in
the western  basin as did  the  concentrations of chlorophyll a.   An  area
of low concentration persisted in the western basin associated with the
inflow of the Detroit River, while Maumee Bay  and the associated .south
shore  area had very high concentrations.   Surface concentrations  in
the central basin  increased as the summer progressed.   Bottom con-
centrations and distributions were very similar  to those of the surface.
This trend was particularly evident in the western  half of the central
basin.  A  distinct gradient  of decreasing concentrations from  west  to
east was evident  through  the  entire summer.

      Following turnover, POC  decreased in the  western  basin,  most
noticeably  in the  Maumee Bay region.   The concentrations  of  chlorophyll
a_ increased  slightly basin-wide indicating a possible settling of detrital
                                   41

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carbon.   Participate organic carbon concentrations  in the central
basin were highest during  October, corresponding to the highest con-
centrations of  chlorophyll a.  As previously noted,  a distinct west  to
east concentration trend was observed with the greatest  central basin
levels occurring in the transition  area between the western and cen-
tral basins.   Since no  stratification existed  during  this time,  resuspended
sediments would also have contributed to  the increased POC levels.

      Particulate organic carbon values generally reflect seasonal
changes  in biomass of a plankton community.   This relationship,
however, does not show good positive correlation during periods when
bottom material  becomes resuspended.   During periods of nonstratifi-
cation,  spring, winter and fall  in the central basin and any  period  of
high winds  in the western  basin,  resuspension of carbonaceous materials
previously settled may  result in high particulate organic carbon values.
Particulate organic carbon concentrations recorded  during  times of
high resuspension represent  a  combination of detrital carbonaceous
material  and living cells present in  the water column.

      Particulate organic nitrogen (PON) concentrations and distribution
patterns were  similar  to those  reported  for  POC during 1974 and  1975.
Similar  fluctuations  occurred throughout the year,  although the magni-
tude of PON was much less.

      Ten-year trends.   Table  11 shows ten-year trends for total  and
soluble reactive  phosphorus and for  total  inorganic, nitrate plus nitrite
and  ammonia nitrogen.   Both TP and SRP indicate improvements  in all
three basins with the greatest  reduction  in the western and the least in
the eastern basin.  With  decreased  loading from  the  Detroit  River this
type of cleansing pattern would be expected.   However,  CCIW/EPA data
from Project Hypo  in  197O (Burns and Ross,  1972), when compared with
1973-1975 data from the present study, show  no significant changes in
open lake concentrations (Figures 9  and  1O).  Similar methodologies
and  statistical treatments were used  for the 1970-1975  period,  but these
differed  from those used  in  1963-1965, which  may  explain the apparent
 improvement.

Chlorophyll

      Chlorophyll,  green plant  pigments essential to photosynthesis, can
be  used  as an indicator of the  relative algal biomass in an aquatic sys-
tem.  An analysis of chlorophyll concentrations over a period of years
may show long term trends  in  algal populations.
                                   42

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             TABLE  11 .  TEN-YEAR COMPARISON OF MEAN
                      WATER  QUALITY IN  LAKE ERIE
PARAMETER
Total Phosphorus
Western Basin
Central Basin
Eastern Basin
Soluble Phosphorus
Western Basin
Central Basin
Eastern Basin
Total Inorganic
Nitrogen
Western Basin
Central Basin
Eastern Basin
Nitrate-Nitrite
Nitrogen
Western Basin
Central Basin
Eastern Basin
Ammonia Nitrogen
Western Basin
Central Basin
Eastern Basin
PERIOD OF OBSERVATION
1963 - 1965
mg/l

0 160
0.065
0.060

0.032
0.010
0.010


0.350
0.176
0.176


0.124
0.090
0.090

0.159
0.086
O.086
tons (M)

3,800
20,000
9, 100

700
3,000
1,500


8,400
53,000
26,700


2,900
27,000
13,60O

3,80O
25,700
13,000
1973 - 1975
mgA

0.035
0.017
0.030

0.005
0.002
0.005


0.298
0.157
0.158


0.274
0.143
0.084

0.024
0.014
0.074
tons (M)

839
5,207
4,554

130
706
759


7,090
48,663
23,984


6,532
44,416
12,751

558
4,247
1 1 , 233
PERCENT OF
1963-64
QUANTITY
PRESENT IN
1973-74

22.1%
26.0
50.0

18.6
23.5
50.6


84.4
91 .8
89.8


225.2
164.5
93.8

14.7
16.5
86.4
Data Sources:

1963-64 - Federal Water Pollution Control Administration
1973-75 - Center for Lake  Erie Area Research
          Great Lakes Laboratory
                                    43

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      In  1967 the Federal Water Pollution Control Administration (1968b)
conducted three  cruises on  Lake Erie during which  chlorophyll a and  b
determinations were made on water samples from 30 stations.  The
mean annual concentration for the  western,  central  and eastern basins
was 23,  9 and 6 >ug/l respectively.

      Glooschenko et al. (1974) reported on chlorophyll  determination
from 10 Lake  Erie  cruises during  the  period April  to  December 1970.
They found  the highest mean  chlorophyll a_ values (11 pg/l) occurred in
the mid-western basin,  with a second maximum  (6 ;ug/l) in the eastern
basin north of Erie, Pennsylvania.  The southern shore of the central
basin was also characterized  by high values, particularly east of Cleve-
land, Ohio.  The lowest yearly means were found in the eastern portion
of the central  basin and  most of the eastern basin (3 jug/I).

      Investigations  by the Center for Lake  Erie Area  Research and the
Great Lakes Laboratory showed a  distinct gradient  in chlorophyll  a^ con-
centrations  from the western  basin to the eastern basin  in 1973, simi-
lar to that  found by Glooschenko et al.  (1974).   Basin  values for  the
period July to October are  given in Table  12.   The  central basin has
been  divided into a  western and eastern  half to demonstrate the marked
gradient across  this basin.   The western half  showed a definite transi-
tion zone due to the influence of large algal populations  in the western
basin, whereas the  eastern half was similar to the  eastern basin  and
contained the lowest chlorophyll a  concentration  in the  lake during the
summer.i  Figure 16  presents a graph of chlorophyll a_ concentrations
in the lake  during the period  June  1973 to March 1975 which  demon-
strates the  relationship of the basins and the seasonal  variations which
occur each  year in  response  to algal populations.

      Trends in  the chlorophyll concentration in  Lake Erie surface
water are  shown in Figure 17.  Although the  1967  data contains both
chlorophyll  a_ and b_, a definite down trend in the western basin biomass
is indicated when compared with the other two basins.   This  trend  is
consistent with other  chemical and biological parameters which also
show a major  improvement in the  western basin and lesser amounts of
recovery for the other two  basins.  The improvement  appears to  be
related to the  reduction in nutrient loading  from the Detroit River and
other tributaries which  enter  the western basin.   Therefore,  the nearly
three-year  flushing  rate  of  Lake Erie would be expected to slow the
response to reduced nutrients in the down stream basins.  If the  pre-
sent trend continues,  increased recovery should  be  observed  in both
the central  and western basins.
                                   44

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        Western Basin I
          ntral Basin *^^ //"
                 /i
           Eastern Basin
      ~l—I—I—I—I—I—I—I—I—I—r-
      J FMAMJJ  A S  O  N
—1	1—|—I—]—T—I—r-
 A  M ,  J  A  5  O  N
i—i—i—r  r ~i—i
M A  M j  j  A  S
Figure  16.   Concentration of chlorophyll a  in  Lake  Erie
                surface  water,  1973-1975.
             WESTERN BASIN
     101-
                                      CENTRAL BASIN
                                                            EASTERN BASIN
                                                                   Sp = Spring
                                                                   Su = Summer
                                                                    F = Fall
           £p £u -  Sp Su F   Sp Su F
            1967     1970    1373-74
                                           1370    1973-74
    "9£7;     Feae^sl Water Pollution Control Aamin. {19683 S. b; - C^lrrscnyi! r-opOrted as corrected a 3. t>
    1970:     Canada Centre for Inland Waters - Chlorophyll reported as corr?de-1 a            -  -
    i;-73-74:  Center for Lake Erie Area Research an^ Great Lakes Laboratory - ^rlc:-orr.yll .-ppcrtpo
      Figure  17.   Trends  in  Lake  Erie surface  water
                       chlorophyll 1967-1974.
                                     45

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         TABLE 12.   AVERAGE  SURFACE CHLOROPHYLL a
                     IN LAKE ERIE - 1973 (JLJG/L)
Date
Mid-July
August-September
Mid-October
Annual Mean
Annual Ratio
Western
Basin
9.36
15.08
11 .38
11 .94
2.70
Central Basin
West half
4.59
4.92
8.95
6.15
1 .46
East half
1 .90
2.30
7.77
3.99
0.90
Eastern
Basin
3.28
3.85
6.12
4.42
1 .00
      During the period 1973-1975 chlorophyll  a_ concentrations  in the
western  and central  basins of Lake Erie  have  increased (Figure 18).
The  peak summer concentration  (volume weighted) in the western basin
has  risen from approximately 12jug/l in  1973  to 21 jug/l in 1975.   In
the central  basin the peak concentration occurs  in fall.  A similar
increase was observed  in this peak,  from 8 jug/l in 1973 to 10^jg/l
in 1975.  Intermediate  concentrations were found in both basins in
1974.

      Volume  weighted  quantities of chlorophyll  ai also  increased in the
western and central basins from 1973 to 1975 (Figure  19).   The central
basin quantities increased significantly between 1974 and 1975  but  the
rise  in the western  basin was less pronounced.

      Table 13 shows the  ratio of chlorophyll  a. concentrations  in the
western and central basins.   The western  basin concentration  during
spring  and summer  is  normally 2 to 10  times greater than the eastern
part of the central basin.  In fall there  is less  difference  in the basin.
The ratios between  1973  and 1975 reveal a trend toward a decreasing
dominance  of  concentrations  in the western basin, particularly  in the fall.
This is probably the result of a decrease  in nutrient loads to  the west-
ern basin via the Detroit River  coupled with the regenerated nutrient
added to the central basin after fall  overturn.
                                  46

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                                       Western Bust
                               Cent
         c MAMJ J ASOND
                1973
JF MAMJ JA SOND
        1974
1	'	1—I	1—1	1—I	1	1	1—r-
JFMAMJJA  SOND
        1975
  Figure  18.   Volume weighted concentration (ug/l)  of  corrected
               chlorophyll a in Lake Erie  1973-1975.
   •- 1500 ..
Figure  19.   Volume weighted quantity (metric tons) of corrected
             chlorophyll a in Lake Erie  1973-1975.
                                 47

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TABLE 13.   RATIO OF CHLOROPHYLL a CONCENTRATION IN
 WESTERN AND CENTRAL BASINS OF LAKE ERIE 1973-1975
DATE
April
1974
1975
June
1974
1975
July
1973
1974
1975
August
1974
September
1973
1974
1975
October
1973
1974
1975
December
1975
WESTERN BASIN
2.91
2.33
3.95
8.78
4.77
9.82
7.45
6.21
4.95
4.75
2.57
1 .56
1 .89
1 .22
0.7.0
CENTRAL BASIN
West Half
1 .44
1 .41
0.80
1 .37
2.05
2.23
1 .90
2.09
2.20
1 .92
1 .62
1 .08
1 .62
0.98
1 .13
East Half
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
                               48

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 Microbial Activity

      This microbial study was undertaken to monitor a select number
 of metabolic  by-products of bacterial  activities  and to  equate these
 parameters to the eutrophic processes occurring  in Lake  Erie.  The
 monitoring of dissolved  methane,  sediment methane evolution and sedi-
 ment methane production potentials was of primary interest.   Secondly,
 an attempt was also made  to estimate the  contribution of  biological
 nitrogen  fixation to the nutrient budget of the lake.  Nitrogen fixation
 potentials were estimated by the acetylene reduction technique.

      The nitrogen fixation in the  aquatic system  is performed mainly
 by the blue-green  algae and certain bacterial species (largely  by
 Azotobacter and Clostridium species).   The  amount of fixation occur-
 ring in the water column or in the sediments may be a relatively
 sensitive indicator of  loading,  particularly when compared to dissolved
 methane  in the water  column and  to methane production potentials  in  the
 sediment.  For  example,  if the microbial  cell  is subjected to a high
 concentration of organic material  that is rich in organic nitrogen,  the
 cell  in most  cases  will  use the organic nitrogen.  If,  however,  the
 external  loading is  rich  solely  in  organic  carbon,  the microbial  cell
 will  be forced to use  inorganic forms of nitrogen or will  resort to
 nitrogen  fixation.

      Because of the ready reserve of dissolved inorganic nitrogen in
 the water column during the 1973-1975 cruises, no acetylene reduction
 potentials were observed during this survey.  However,  sediment  values
 indicated maximum fixation potentials (3-6 nanomoles C2H4/g sediment
 per  day)  in the mid-portion of  the western and  central basins.   The  in-
 shore  regions and the eastern sector  of the  central basin had  the  lowest
 potentials.   In general,  the data tend to indicate  that a sufficient quan-
 tity  of fixed nitrogen, either organic or dissolved inorganic  forms, is
 available in this ecosystem.

      The methane data obtained during this investigation showed some
 interesting trends.   In early spring a minimal quantity of methane was
 found throughout the water  column.   The concentration was less  than
 10 parts  per  billion  (ppb),  which  is at the lower  detection limit  of the
chromatograph ic system utilized.   This low concentration  was  primarily
due to the low temperature and well oxygenated  conditions in the entire
lake.  A  rapid increase of dissolved methane occurred during  the  late
spring -  early summer period of  1974.   This period demonstrated con-
sistent increases in  methane concentrations and  culminated in the yearly
maximum during June.  This maximum can be  attributed  to  the warming
of the  water column, to the residual organic  build up during the winter
and to the increase in available organics caused by the spring diatom

                                    49

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 bloom.  A number of geographic or basin effects  are evident  from
 methane concentration contours.  The entrainment of colder eastern
 basin  water into the central basin is demonstrated by low methane
 values in  the bottom  and particularly in the upper hypolimnion waters.
 The warmer surface  and lower epi limn ion waters  are unaffected by  the
 colder entrained water.   The surface water of the mid-portion of  the
 central basin possesses  a uniform horizontal distribution of methane
 but there  is evidence of two western basin effects.  One is the low
 flux of methane observed entering from  the  western  basin through
 Pelee  Passage, the second is the significantly higher  impulse  recorded
 lakeward of Sandusky Bay.  The colder hypolimnion water  is  not
 affected by the western  basin water,  but is  significantly influenced
 by  the previously mentioned eastern basin water.
      The  mid-summer cruises show a significant decrease in the con-
centration of dissolved methane.   During the development  of anoxia
and  at the time of maximum  anoxia,  the methane  concentrations were
surprisingly low.  The annual fall turnover  and  post-turnover  periods
resulted in a twofold increase in the methane  concentrations of the
water  column as  compared to the  late summer cruise.  Of the two
major western basin tributaries,  Detroit and Maumee  Rivers,  only the
bottom  water of the  Maumee  made a significant  direct contribution to
methane to the  western basin.  A major difference between the methane
concentration in the  surface and bottom  water indicates that the warmer
western basin water was  flowing up  the  Maumee River estuary,  forcing
the colder river water underneath.  The western basin possesses  a
smooth linear gradient between the Detroit and the Maumee Rivers.
Methane production observed  along the south shore appears to be  related
to organic loading from the Detroit River.   The mid-winter cruise rep-
resents a  stabilization of the  methanogenesis of  the central basin.
Sandusky Bay,  Fairport and Ashtabula Harbors represent  locales  of
obvious organic loading to the lake surface water.  Unlike the nitrogen
fixing potentials  of the sediments the maximum values for methane pro-
duction potentials (0.03-0.06  mg CH4/g-day were  observed in  the  neai—
shore sediments, particularly along  the  south  shore in the vicinity
of major  tributaries.  This potential  appears to be a good indicator of
organic loading.   In situ  measurements  in Cleveland Harbor (July 1975)
yielded methane  evolution  rates in excess of 70  mg/m2-hr.   However,
the overlying water column dissolved methane concentrations ranged
from 10-45 ppb (methane solubility in water is approximately 20 ppm).
Therefore the rate of  methane oxidation  is apparently  very rapid.   This
rapid oxidation  would result in a  high oxygen demand in the harbor
region.
                                    50

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Phytoplankton

      Numerous  investigations  of phytoplankton populations in restricted
bays,  river-mouths and  nearshore areas  of  Lake Erie have  been under-
taken  in the past 50 years.  Maumee and Sandusky  Bays are highly
productive, developing large phytoplankton populations, thus  being  a
major source of biomass to the open lake.  Except  for the  Detroit
River  with  its relatively clear mid-channel flow, high densities  of
phytoplankton were  found in  the regions of mixing  between turbid,
nutrient-rich  tributary waters  and  clear  lake waters.

      Of the three Lake  Erie basins, the western basin has  received
the most extensive  coverage.  During  1929 and  1930,  phytoplankton
survey samples  were taken at numerous stations in  the western  basin
(Wright,  1955).   By correlating  phytoplankton  composition and quantity
in the island  region to areas of tributary  influence in the western basin,
Wright concluded that the  island region was  richer in phytoplankton  than
either the central or  eastern basins, Lake St. Clair, or the mouth of
the Detroit River.  However,  the  areas  near major tributaries (Portage,
Raisin and  Maumee Rivers)  were significantly more productive than the
island region.  This was attributed to the shallowness of these areas
as well as  to their being major areas of nutrient  input.   A  seasonal
pattern was observed including a spring  pulse consisting almost  exclu-
sively of diatoms (Asterionella,  Stephanodiscus, Melosira and Synedra
comprised the major  portion of the peak) with greens and blue-greens
predominant through the summer and into the  early  fall.   The blue-
green  pulse followed that of the greens and coincided with the autumn
diatom peak.   The  taxa  comprising the blue-green pulse were Coelo-
sphaerium, Oscillitoria, Merismopedia and Gomphosphaeria.  The only
other taxon of importance  was Microcystis which occurred during  late
September.   The fall diatom pulse was comprised of the same taxa
found during the vernal pulse, with the addition  of Fragilarta.

      Phytoplankton community studies undertaken during the late 193O's
and early  1940's by Chandler (1940, 1944) showed that annual diffei—
ences  in phytoplankton populations  were largely  influenced by meteoro-
logical conditions.  Turbidity caused by  wind—induced bottom resus-
pension and the  sediment load  contributed by southern tributaries have
a very pronounced effect on phytoplankton pulses.   For each of  the
years,  the  seasonal composition of the standing  crops was similar,
but the magnitude of the group present varied.   Diatoms  were dominant
in both the spring and autumn  pulses; however,  during the spring  they
comprised up to 90 percent  of the total standing crop.   The maximum
                                    51

-------
 spring  pulse  occurred as early as February and  as  late as  May
 through the years 1939 to 1942.  The vernal pulse was  dominated by
 Asterionella Formosa  each year.  The autumn pulse began during late
 July or early August and was comprised of diatoms, greens,  and blue-
 greens.  The greens and blue-greens  together accounted for approxi-
 mately 50 percent of the community, with the blue-greens comprising
 the greater portion.   Unlike  the spring  pulse, the fall diatom  pulse
 was co-dominated by several taxa,  principally Melosira.  During  late
 fall  and winter the diatoms again comprised greater than 80 percent
 of the algal  population.   The standing crop of phytoplankton  peaked in
 the spring, declined during mid-summer,  and peaked again  during  late
 summer continuing into  early fall.   The winter months exhibited  low
 standing crops.

      Britt et  al.  (1973) examined phytoplankton  from six stations 'in'
 the island region during the summers of 1961, 1962, and  1963.   In
 comparing the percentage of  composition of phytoplankton by taxonomic
 divisions,  a pronounced  increase in  dominance of blue-greens  was
 noted since 1929.   Microcystis and Aphanizomenon  were dominant dur-
 ing all  three  years.  A  change in the dominant species of diatoms
 also occurred.  Hohn  (1969)  compared diatom data  from several  sui—
 veys from 1938  through  1965.  He found the  predictable spring and fall
 diatom  pulses, but in  addition,  a summer high was  also noted in the
 1960's.  By the spring of 1955, the  actual intensity of the vernal pulse
 had  increased by a factor of  almost  eight  compared to that  of the
 spring of 1939.   Hohn found  that the  major taxa  reported during  the
 early 1940's were still present, but  that their relative importance had
 changed significantly.  Dominance had been assumed  either  by taxa
 not previously recorded  or taxa which had only occasionally been
 observed.   Verduin (1964) documented the change in dominant  species
 composition (prior to 1950 to the period of 196O-61)  in the western
 basin as a shift from Asterionella formosa, Tabellaria fenestrata and
 Melosira ambiqua to Fragilaria capucina,  Coscinodiscus radiatus, and
 Melosira binderana.  He attributed this  change to increased nutrient
 loading  from  agricultural run-off.

      During 1950 and  1951,  Davis (1964) obtained samples  from  nine
stations  in and around Cleveland Harbor and found vernal and  fall peaks
similar to those occurring in the western  basin.  During the spring
pulse diatoms  constituted nearly 10O percent of the community while
 the greens and blue-greens were  more important in  the  fall.  Using
data supplied  by the water treatment  facilities of Cleveland,  he docu-
mented  an increase of 443 cells/ml per year from  1927-1964 with a
period of substantially greater increase  (122 cells/ml  per year)
                                    52

-------
occurring between 1956-1964.  The major dominant spring diatom changed
from Asterionella to Melosira  during  the early  1950's, whereas the fall
dominant shifted from  Melosira to a mixed  dominance of Melosira,  Fra-
gilaria  and  a number of blue-green species.

      Samples obtained for the International Joint Commission  in 1966
and  1967 from Canadian water intakes (one  municipality in the  western
basin, two  in the central basin,  and three in the eastern  basin,  substan-
tiated a decreasing  west to  east  trend in numbers of plankters.  The
western basin had a high population of blue-greens during the summer
and  fall  not  found in the central  basin or eastern basin  stations.  Dia-
toms remained  the  dominant plankton group  in the spring, fall  and  winter
in all basins, while during the summer the greens and blue-greens were
predominant.  In a  similar  study conducted by the Ohio Environmental
Protection Agency,  phytoplankton  was examined  at 10  intakes along the
Ohio shoreline and  showed similar seasonal trends and dominant groups
from 1968 to 1972.   This study also  indicated a tentative decrease  in
total counts  during  this period.

      The first  basin-wide phytoplankton survey  of the central basin was
conducted by Burkholder (Fish, 1960) at 27 stations in June, July,
August  and  September of 1929.  Diatoms were  the predominant group
during each  cruise  except in August when all  three groups were  equally
represented.  Greens were  present through the  entire study but were
most important during September.  Blue-green  populations were greatest
during June  with a  smaller  pulse occurring in September.  Many spe-
cies found to be common during  the study are also commonly found in
the lake during the  1970's.   Not until  1963  through 1968,  when the
Federal  Water Pollution Control  Administration  undertook surveillance
programs, was the  entire lake investigated.   During  both study periods,
spring and fall  pulses  of diatoms occurred in both central  and  western
basins with a decrease in algal density from west to east.  Blue-green
pulses occurred  during the fall of 1963 and 1964 to a much greater ex-
tent  than during  the 1967 and 1968 period.  The most thorough Lake
Erie phytoplankton study to  date  has been by Munawar and Munawar
(1976).   Species composition and biomass values were determined  for
each basin from April through December of 197O.  On the average,
diatoms  were found to comprise  more than  50 percent of  the phytoplank-
ton in both  the western and central basins,  while the phytoflagellates
were found  to be of lesser importance.  The  blue-greens were most
significant in the western basin,  primarily in late summer.

      From July 1973 through May 1974, 87  plankton samples (two  per
week) were collected with a  Wisconsin plankton  net (80-micron mesh)
in Fisheries Bay (Station 77) of  South Bass  Island in western  Lake Erie
(Figures 20-23).  The purpose of this special study was  to develop

                                   53

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120,000


110,000


100,000


90,000

80,OOO

'0,000


CO,000

50,OOO


-10,000 •


30,000


20, OCO

10,000 •


    0
                      [njivtduai Sample Values

                      Woncnly p,;eans
          1  i;  , _15 ''51  15  1  15  1
           J"'S   =ep£  Oc;   N'ov   Cec  -
                                                      1   13 1   15 1   1=
                                                       Mar 4prl  Mav
   Figure 20.   Total  phytoplankton populations  at Put-in-Bay.
120,000

1 !0,OCO -
IOC, CCO .
90 , OCO -
ec.ooo -
70,000 -
•=0,000 -
5C.OGC -
•iO.OOO -
30,000 -
20 , 000 -
1C, 000 -
0 •

• Individual iarr.^le Va'.jes
• .Voncnv Means

•'
«
t.
j
X
X
£
•J\
'c
?
^ • •
1
'
• '
. '. ' •," .'.
' •
- --, 	 T— r- •*-- " ''
              15 '  '5  '  '^  1  15  1  15 1  .:  1  15  1  15  1  15  1  1b
              -.3  Sep:   Oc:   ,\^v   Det   ^^    en  -Va'  ior-l
                                     U
                                                                    ,la
Figure 21.   Total  bac il lap iophycean  populations  at Put-in-Bay.
                                      54

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     2000
                                        Inoividual Sample Values

                                        Monthly Means
         1  15  1  15  1  15 1  15 1   15 1   15 1  15 1  1;  1  15  1  15  1  15 31

         July  Aug  Sept   Oct Nov   Dec   Jan   Feb  Mar  April   May
         1973                           1974
Figure 22.   Chlorophycean populations at  Put-in-Bay.
    28,000
         1
                                       * Individual Sample Values

                                       • Mon:hly Means
          1  15  i  15 1   15 1  15 1  15 1  15  1  15  1  15  1  IE  1  15  1  15  jl
          July  Aug. Sept  Oct  Nov   Dec  Jan  FeD   ,\'.3-  April   May
          1973                          1974



Figure  23.   Myxophycean  populations at Put-in-Bay.
                                55

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trends  since the earlier works of Chandler and Hohn.  Diatoms were
present in all  collections; from  November to May they comprised  more
than 90 percent of the phytoplankton population, while from July through
September they made  up less than 25 percent of  the  total population
(Figure 21).   Changes in the structure of the  diatom population since
Chandler's early work were obvious.  He found that  Gentries, Melosira,
Cyclotella and  Stephanodiscus generally  dominated fall pulses and  pen-
nates,  Asterionella, Fragilaria, Synedra, Tabellaria and Diatoma domi-
nated spring populations.  Chandler also found Asterionella to be very
abundant and hypothesized that the dominance of this  genera in  the spring
could be due to a competitive advantage gained by maintaining relatively
high winter populations.

      During the present study the fall pulse was  essentially absent and
the total diatom population was strongly dominated by Melosira in all
months but August when Fragilaria was  slightly more abundant.  Asteri-
onella peaked  in March 1974  at  over 8,000/Uter,  but accounted for only
8  percent of the total  phytoplankton  population.  It reached its  greatest
abundance in relation to the  total phytoplankton population  in November
when it constituted  26  percent of the population.  However, at the same
time Melosira  made up 58 percent of the population.   Hohn (1969) ob-
served  that over the years Asterionella  had  not decreased in numbers,
but rather other taxa,  especially Melosira, had increased greatly  causing
Asterionella  to occupy a smaller portion of the population.  The present
results tend  to support this hypothesis; Asterionella  population  reached
its highest levels in November  1973 and March to May 1974, which would
correspond to  the pulses  observed by Chandler.   Other taxa found to be
abundant by Chandler,  Fragilaria, Synedra and Tabellaria, were  not
found in significant  numbers in this  study except  in December 1973 when
Fragilaria composed 14 percent  of the phytoplankton population  and May
1974 when Tabellaria composed 23  percent of the population.

     The green algae  were found to be  the most  diverse group by
earlier investigators.  The major difference between  the  results of
the present study and those of previous  years  was in the composition
of the  population.  Chandler listed the taxa in order  of dominance as
Dictyosphaerium, Schroederia,  Scenedesmus,  Pedlastrum,  Oocystis
and Coelastrum.  One  of these,  Dictyosphaerium, was not observed in
this study.   Pediastrum  has increased in importance  as the dominant
chlorophycean  July through December 1973.

     Chandler found that the  blue-greens were very  much affected by
temperature and turbidity and, therefore, comparisons between  years
were very difficult.  He listed the most common  taxa of  1942 in order
of abundance as Aphanizomenon-Qscillatoria, Merismopedia, Coelosph-
aerium, Chroococcus,  and Microcystis.   Vila-Pinto (1964) found that

                                    56

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Microcystis  was the dominant phytoplankter during the summers of 1961-
1963  with Aphanizomenon-Qscillatoria second  in abundance.  In the pre-
sent study Microcystis  peaked  in  August 1973 and  represented three pei—
cent of the  total phytoplankton.   This was  the second highest percentage
for any blue-green taxa; Aphanizomenon-Oscillatoria, the most abundant
blue-green taxa, which peaked in September  1973,  represented 58 per-
cent of the  total phytoplankton.   Chandler often found blue-greens  in all
samples from  a particular year,  whereas, none  were found  in samples
from  December  1973,  February  1974,  or April 1974 (Figure 23).
Zooplankton

      Early studies of lake-wide zooplankton populations are  not avail-
able.  Wilson (Fish,  1960) studied the eastern basin in 1929-30 and
Chandler (1940)  investigated the western basin during the  late 1930's.
During the past  10 years three extensive  Lake Erie  zooplankton sur-
veys  have been made in addition to the present study.   Davis (1969)
made two transects of the entire lake  (30 stations) in July and Octo-
ber  1967 and  a partial  transect in January 1968.  Watson and Carpen-
ter (1974) sampled zooplankton  at 30 different stations during 10 cruises
from April to December 1970 and  Patalas  (1972) transversed the  lake
sampling at 34 stations during two cruises  between June and August
1972.  The present study  included six  cruises between May and Nov-
ember 1974 with samples  at 51 stations in  the western  and central
basins.

      Only the 1967 and  1974 surveys included rotifers in addition to
crustacean zooplankton.   In  spite of  their relatively  small size, rotifers
comprised a significant percentage of the  zooplankton biomass (6-40
percent  in the western basin).  High numbers of rotifers  are considered
indicative of enriched conditions.

      Cladocerans  comprised the highest percentage of the zooplankton
biomass  during the late  summer and fall of 1974.  High populations  were
observed in both basins,  particularly during the early summer and
autumn pulses.  Cladoceran numbers have increased steadily since
1939, and this group  currently  has higher  concentrations  in the  western
basin of Lake Erie than elsewhere in the  Great Lakes.   Cyclopoid cope-
pods  were dominant over calanoid copepdds throughout  the year.   The
greatest  numbers of copepods occurred during June  and July in  both
basins; this population declined  steadily through November.   Through the
years cladocerans  and cyclopoid copepods have gradually outnumbered the
once  dominant calanoid  copepods.  The trend  from a calano id-dom inated
to a cyclopoid- and cladoceran-dominated  community  has been observed
in other  lakes which have  undergone  nutrient  enrichment.

                                   57

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Benthic  Macro invertebrate Fauna

      The  open water benthic fauna of Lake  Erie has undergone sig-
nificant  changes in the  past  50  years.  Prior  to  and during the 1930's
the bottom fauna  of the western basin was dominated by the burrowing
mayflies Hexagenia spp. and the  caddis fly,  Oecetis  inconspicua.
Other taxanomic groups were relatively unimportant by comparison,
although tubificid oligochaetes were abundant near river mouths.   Wright
(1955), working with  1930  data,  categorized  the western basin  into sev-
eral zones of pollution  based on the number of tubificid oligochaetes
present: light pollution  100-999/m2; moderate  pollution 1000-5000/m2;
and heavy  pollution greater than 5000/m2.   Wright classified most of
the western basin as  unpolluted (less than 100/m2) whereas the mouths
of the Detroit,  Maumee, and Raisin Rivers  were considered moderately
to heavily  polluted.

      Revisiting Wright's stations, Carr and Hiltunen (1965) found
that by 1961:

      1)  Hexagenia spp. had decreased to less than one percent
         of its previous abundance*

      2)  oligochaetes had  increased ninefold in density, thereby  greatly
         expanding the  areas defined  as polluted  using  Wright's index,

      3)  chironomid densities had increased fourfold, snails increased
         sixfold,  and sphaeriid  clams increased twofold.

Britt (1955) reported  a drastic  decline in the mayfly population during
the summer of 1953 due to thermal stratification and bottom water
oxygen depletion in the western basin.  By  1965,  Britt et  al.  (1973)
considered Hexagenia spp. to be  nearly extinct in the western
basin.   During  the present study (1973-1975),  no Hexagenia spp.
were  collected.

      In  1963 and  1974, the  U.S.  Public  Health Service conducted
spring, summer,  and fall  surveys of Lake Erie (Federal Water Pollu-
tion Administration, 1968a).  The FWPCA concluded that most of the
western  and central basins were  characterized  by a lack of pollution
sensitive amphipods and contained a preponderance of pollution tolerant
species of sludgeworms, bloodworms, fingernail  clams and nematodes.
The report listed  34 species in  Lake Erie with an  average benthos
density of  1164/m2 and 1861/m2  for the western  and central basins,
respectively.
                                   58

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      The present benthic fauna of the western  basin  is dominated by
tubificid oligochaetes,  with  the genus Llmnodrilus making  up over 61
percent of the population.   Chironomid  larvae comprise the  next  most
abundant group,  nearly 20 percent of the bottom  fauna.  Sphaeriid
clams make up less than 10 percent of the organisms, except near  the
Detroit River where their numbers reach 20  percent  of the total  popu-
lation.  The central basin fauna is likewise dominated by  oligochaetes.
Peloscolex  ferox is the dominant  species,  but Limnodrilus spp.  frequent-
ly comprise a significant portion  of the  populations.  Chironomids form
major components  of the fauna, especially  adjacent to the  north shore
(up to 30 percent).   Sphaeriid clams are also abundant throughout the
central basin where at times they are co-dominant with oligochaetes
(up to 50 percent).   Approximately 8 percent, numerically,  of the
benthic fauna is  composed of 15 minor  taxa.   These  include  leeches,
amphipods,  isopods, polychaete worms,  mysids,  coelenterates, flat-
worms  and  caddisflies.  The most common of these  is the aquatic iso-
pod, Asellus  racovitzai racovitzai.

      If Wright's (1955) pollution  index is applied to the  1973-1975
sampling  period, most of the western and central basins would be con-
sidered moderately polluted.  Although  the  average density of the bottom
fauna has nearly doubled in the decade  since the  USPHS  1963 and 1964
surveys (largely due to increases  in oligochaetes),  caution must  be
exercised in the application of this index to open water area of the  lake
where hypolimnetic anoxia can influence  the benthic populations.

CONCLUSIONS

      The fundamental  conclusion of this assessment  is that during the
first half of this decade no significant decrease in the loading of nu-
trients to Lake Erie has taken place.   Therefore,  during  this period
the  concentrations and quantities  of nutrients within the waters of the
lake have remained relatively stable.   An  encouraging sign  of nutrient
control is that although no  decreases have  been observed, the constant
increases which have taken place  in proceeding decades have been
stopped.  Other indicators  of eutrophication, such as hypolimnetic
oxygen depletion rates, chlorophyll concentrations, methane  production,
plankton and  benthos populations,  dissolved solids and turbidity,  have
remained high since 1970 but also relatively stable.

      Most  of the nutrient  loading to Lake  Erie occurs in  the western
basin.  The largest quantity is delivered by the  Detroit River, but  the
highest concentrations  were observed near  the  mouth of the  Maumee
River.  The  western and central  basins are effective sinks  for nutrient
loading; approximately 82 percent  of the phosphorus carried  to  the lake
                                    59

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by the tributaries  remains  in bottom sediments.   Up to 10 percent  of
the phosphorus delivered to the  lake  can be regenerated under anoxic
conditions.   However, physical regeneration due  to  storm resuspension
of sediment  can have a  larger  impact on internal nutrient loading, par-
ticularly during  non-stratified  periods.

      Meteorological variations such as  wind,  solar radiation  and pre-
cipitation appear to have a much more profound  effect  on the trophic
status of Lake Erie than attempts at nutrient  control.  For example in
1975,  light winds during  the period  of thermocline formation  resulted
in a thicker hypolimnion  in the central basin.   This increased reservoir
of oxygen reduced  the area of anoxia  by over  95 percent and  thereby
decreased  the amount of regenerated phosphorus  from the sediments
by over  70 percent from the previous two years.  Also,  because of
high concentrations of nutrients  in the lake, particularly  the  western
basin, the limiting  factor in algal production appears to be sunlight.
Precipitation also  plays  a role in nutrient concentrations;  high rainfall
in the early 1970's over  the upper Great Lakes basins resulted in
record-high  flow rates  in the Detroit  River  in 1972 and 1973.  The
concentration of nutrients,  although  not  the quantity, was  lowest during
this  period indicating dilution by excessive precipitation.

      Although the  effectiveness  of nutrient controls in  reversing eutrophi-
cation in Lake Erie cannot be demonstrated, the halting of further deg-
radation is an important first  step.   Also, many of the new  treatment
facilities are just  now being placed  in operation.   Modifications  in agri-
cultural  practices  will reduce  the loading of nutrients to  the  tributaries,
but these changes  will not be reflected  in water  quality improvements
for several years  due to the slow migration of sediment  to the lake.
It is  important that this start  at improving the conditions of  Lake Erie
be continued and that new methods of lake  restoration be  explored.

TECHNICAL APPENDIX

      Because  of space  limitations, much of the supporting data for
this  report  could not  be  printed  at this time.   This information,
largely in the  form of distributional  contour maps is being compiled
for a Technical  Appendix which will  be printed in a limited quantity.
The  Appendix will  include data on physical  measurements, nutrient
chemistry,  bacterial activity, plankton and  water quality contouring
by computer graphics.
                                    60

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 REFERENCES


 American Public Health  Association.   1971.   Standard methods  for
      the examination of water and sewage.   13th Ed. Amer.  Public
      Health Assoc.,  New York.  847  p.

 Beeton, A.M.   1963.   Limnological  survey of  Lake Erie,  1959-
      1960.   Great Lakes  Fish.  Comm.  Tech. Rept. 6.  32  p.

 Britt,  N.W.   1955.   Stratification in western  Lake Erie in summer
      1953: effects on Hexagenia (Ephemeroptera) population.
      Ecology 36(2):239-244.

 Britt,  N.W.,  J.T. Addis  and R. Engel.  1973.   Limnological studies
      of the island areas  of  western Lake Erie.  Bull.  Ohio Biol.
      Survey.  4 (3): 1-89.

 Burns, N.M.  (ed.)  1976.  Lake Erie in the  early seventies.  J.
      Fish.  Res. Board  Can.   33(3):349-645.

 Burns, N.M.  and C.  Ross (eds.)  1972.  Project Hypo.   Canada
      Centre  for  Inland  Water,  Paper No. 6 and USEPA  Tech. Rept.
      TS-05-71-208-24.   182 p.

 Carr,  J.F.   1962.  Dissolved oxygen  in Lake  Erie, past and present.
      Univ.  Mich., Great  Lakes Res.  Div. Pub. No. 9.  p 3-11.

Carr, J.F. and J.K.  Hiltunen.   1965.   Changes  in the bottom fauna
      of western Lake Erie from 1930 to 1961.    Limnol.  &  Oceanogr.
      10(4) : 551-569.

Carr, J.F., V.C. Applegate and M.  Keller.   1965.  A recent occur-
      rence of thermal stratification and low dissolved oxygen in  western
      Lake Erie.  Ohio J.  Sci.   65(6):319-327.

Center  for Lake Erie  Area Research.  1974.   Procedures manual -
      1973.   USEPA Grant No.  R - 802543.   Ohio  State  Univ.   63 p.

Chandler, D.C.   1940.   Limnological studies of western  Lake Erie.   I.
      Plankton  and certain  physical-chemical data of the Bass Island
      region,  from September,  1938, to November,  1939.   Ohio  J.
      Sci.   40(6):291-339.

Chandler, D.C.   1944.   Limnological studies of western  Lake Erie.   IV.
      Relation of Hmnological and climatic factors to  the  phytoplankton
      of 1941.   Trans. Amer. Microsc. Soc.  63(3):203-236.

                                  61

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  Davis,  C.C.   1964.  Evidence For the eutrophication of Lake Erie from
       phytoplankton  records.   Limnol.  Oceanogr.  9(3):275-283.

  Davis,  C.C.   1969.  Seasonal distribution, constitution and abundance
       of zooplankton in  Lake Erie.  J. Fish. Res. Bd.  Can.  26(9):
       2459-2476.

  Dobson, H.H. and  M. Gilbertson.  1971.  Oxygen depletion in  the
       hypolimnion of the central basin of Lake  Erie.   Proc. 14th
       Conf. Great  Lakes Res.,  Internat.  Assoc.  Great Lakes Res.
       1971:743-748.

  Federal Water  Pollution Control Administration.   1968a.  Lake  Erie
       environmental summary:  1963-1964.  U.S. Dept.  Interior.
       170 p.

  Federal Water  Pollution Control Administration.   1968b.  Lake  Erie
       surveillance  data  summary: 1967-1968.   U.S. Dept. Interior.
       65 p.

  Fish, C.J. and Associates.   1960.  Limnological survey of eastern
       and central Lake  Erie,  1928-1929.    U.S. Fish and Wildlife
       Serv.,  Spec.  Sci.  Rept.  - Fisheries No. 334.   198  p.

Glooschenko, W.A.,  J.E. Moore, and R.A. Vollenweider.  1974.
      Spatial and temporal  distribution of chlorophyll a_ and pheopig-
      ments in  surface waters of Lake Erie.  J.  Fish.  Res.  Board
      Can.  31:265-274.

Herdendorf, C.E.  1970.   Lake Erie physical limnology cruise,  mid-
      summer 1967.  Ohio  Div.  Geo. Surv.  Rept. Invest. 79. 77 p.

Hohn,  M.H.   1969.   Qualitative and quantitative analysis of plankton
      diatoms.   Ohio Biol.  Surv.   3(1 ):208-211 .

Munawar, M.  and I.F. Munawar.   1976.  A lake-wide study  of phyto-
      plankton biomass and its species composition  in Lake Erie,
      April-December,  1970.   J. Fish. Res. Board Can.  33(3):581-600.

Patalas,  K.  1972.   Crustacean plankton and the eutrophication of St.
      Lawrence Great Lakes.  J.  Fish.  Res. Bd.  Can.   29:1451-1462.
                                  62

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Thomas, N.A.  1963.  Oxygen deficit rates  for the central  basin of
      Lake Erie.  U.S. Public Health Service,  Robert A. Taft Sani-
      tary Engineering  Center,  Cincinnati.   8 p.

Verduin, J.   1964.   Changes in western Lake Erie during the period
      1948-1962.  Verh. Internat.  Verein.  Limnol.  15:639-644.

Vila-Pinto,  I.   1964.   Studies  of phytoplankton  in  western  Lake Erie
      from the years 1961, 1962, 1963.  M.  Sc.  Thesis,  The Ohio
      State  Univ., Columbus.   54 p.

Watson,  N.H.F.  and G.F. Carpenter.  1974.  Seasonal abundance
      of crustacean zooplankton and net plankton biomass of  Lakes
      Huron, Erie and  Ontario.  J. Fish.  Res.  Bd. Can.  31:309-317.

Wright, S.   1955.   Limnological survey of western Lake  Erie (1928-
      1930).   U.S. Fish and Wildlife  Service.  Spec.  Sci.  Rept.
      No. 139.  341 p.
                                  63

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                                 SECTION 2

                HISTORY OF LAKE ERIE WATER QUALITY

                              Clarence E.  Taft
                            Department of  Botany
                         The Ohio  State University
INTRODUCTION

      Documented history  of Lake Erie water  quality as we  now consider
quality standards must  begin approximately with the past  fifty years.   Few
if any technical  studies of this  nature  exist prior to 1920.   However,
there  are  numerous recorded observations from the late  17th, through the
18th,  and  into the early 19th  centuries.   From these, water quality of the
lake  in those early years can be inferred.  Mostly these are from the
island region, the middle basin, and along the  south shore.


EARLY HISTORY

Island Region

     As early as 1688, one Baron de  Lahontan stated that "Lake  Erie
assuredly  'tis the finest Lake upon earth."  Many of the  early reports
refer to water clarity or  to water color.   A  Captain Jonathan Carver  in
1762 spoke of the many acres of large pond lilies around  the islands, with
leaves closely spaced and myriads of snakes  on the leaves.  This can
mean only one thing about water clarity in those areas.   It was clear  and
transparent.  Submerged  and  emergent aquatics which remained in some
of the south shore harbors until relatively recent years have now largely
disappeared.  Turbidity due to  increased  sedimentation, or  increases in
plankton populations, with consequent low  light penetration have  taken their
toll.   This transparency of the  water was further substantiated in  1804
when sailors from a becalmed vessel at Middle Bass  Island  watched four
to six pound bass take their baited hooks  at fifteen  feet below the  surface.
Again  in 1804,  a traveler reported Lake Erie to be a very  beautiful body
of water which  was a beautiful deep green color and with admired trans-
parency.   The author of the statement also thought, without  exception, it
was the sweetest he had ever drank.
                                   64

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      These  previous reports that suggest outstanding water quality pertain
 mainly to off-shore waters rather than to  shoreline  conditions.  Granted,
 the  island region which  we now  consider surrounded by  low  quality water
 was involved, but one must remember that these islands were largely
 unpopulated  except  for Indians who  hunted  there winters.

Inshore Regions

     The quality of inshore waters  can be  readily  inferred when one vis-
ualizes the Cleveland,  Ohio area with  its 16 dwellings  in 1811  as reported
by John  Melish.   The river  (Cuyahoga) was stagnant, contaminated  with
decaying vegetables (algae?,  aquatics  ?)  and  putrid animal substances.
The  odor was almost insufferable.  The discharge of this effluent  into the
lake certainly must have occurred.   It probably was no  better when Maxi-
milian, on 23 June  1834 reported "the dark brown waters of the Cuyahoga
are strongly contrasted to  a considerable distance  with those of the lake."
This condition of inshore water is further  substantiated by James Flint
who wrote in October 1820 that at Venice on the south shore,  confervae
(algae) washed ashore by wind and waves,  and that this  debris emitted
disagreeable effluvia.  In modern terms, it stank.  Though the alga
Cladophora   was not identified as such by  Bailey until  1848,  there  is no
reasonable doubt that Flint's  "confervae" (a term used at that  time for
any algae) was Cladophora.   It also  points up the fact that Cladophora
was  extant along the beaches in quantities  similar to what we  experience
today along all stable shores. John Havison  in  1822 had previously
reported  Lake Erie beaches  strewed with dead fish and shells.  Water
quality along  beaches could not have been of the best.

     Our knowledge of inshore water  quality in 1828 is further extended
by J.J.  Bigsby who wrote  that Lake Erie inshore water  in a gale  is ren-
dered  turbid by  sand and mud from the  bottom,  but that water some dis-
tance  into the lake  is good.   Also,  in summer,  near shore it  (water)  is
much  contaminated  with  animal and vegetable matter in a state of  putrifi-
cation.  Turbidness after storms appears to have been one of  the  most
noticeable characters of  Lake Erie  water.   Daniel Drake again referred
to it in  1842  when  he wrote  that shallow Lake Erie was  less transparent
than the deeper lakes above,  and  that  wind  agitates it to  the bottom with
slime  being thrown  up.   Though  inshore water was undesirable for domes-
tic  use,  water that  entered the lake from the Maumee  River in 1873 must
have been potable as Toledo used raw water from the  river  in city mains.

Swamp Regions

     The first reference to water temperature is by Bigsby in 1828 when
                                   65

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 he stated that shoal water is heated to temperatures from 90°  to 95°  and
 that the steaming  swamps of western Lake Erie are universally full of
 putrifying  substances.  These occasion "prevalent bilious remittments."
 Today most of the swamps are gone and  water temperatures probably sel-
 dom exceed 80° F.

     An early  reference  to the "Black  Swamp" whose history is intimately
 interwoven with that of western basin water quality was by Daniel Drake
 in  1848.   He described the immensity of  the  area, the huge forest trees,
 the rotting vegetation, and the stagnant,  black water.   Martin Katz  gives
 us further  insight into the swamp  and what its  destruction by clearing and
 draining from late 1850  on into 1870  meant to the lake.

     This black, highly  nutrient loaded water flowed through Maumee Bay
 into the western basin where it increased turbidity,  sedimentation, color,
 and the  nutrient load.  The  accelerated deterioration of water quality  in
 Lake Erie's western  basin may well have begun with this  event.

 Pollutants

     The first  recorded  indication of deteriorating water quality caused  by
 increasing phytoplankton  was  what  was  probably an algal bloom in 1859.
 August  A.  Fahnestock commented  on the  "green scum" of  Maumee  Bay.
 It was also about that period that Toledo was  known as "frogtown" because
 of immense  numbers  of frogs that swarmed over the town from the  vege-
tation choked shorelines.

     Another report that  specifically  refers to water quality in the western
basin was  by Thomas Blackwell in 1866.   He wrote  that a moderate gale
 raises a sea in  Lake St. Clair which becomes  turbid  from detrital matter
from the muddy bottom.   This is  then  distributed  through  the Detroit
 Straits  into  Lake  Erie where ordinary  storms also disturb the  bottom and
 redistribute  sediments (and their nutrient load).

     A  much greater water quality problem arose sometime around  1900
when C.E.  Slocum reported in 1903 significant contamination of water by
 mineral  salts and  petroleum from  wells along tributary streams.  Previous
to that  date,  in  1894,  fishermen were complaining that petroleum from
adjacent oil  fields was responsible  for  a  decline in fishing.  The problem
 became worse rather than better if we  are to believe  G.M.  Grant's rather
 dramatic statement in 1922.   He stated,  "Odors and sediments of oils,
 sewage, and wastes so fouled the  water and bottom in the  west end  of Lake
 Erie, fish can  no  longer  find food or live in  poisoned  areas.   Thousands
 of dead fish are on the surface.   The same conditions contain along Lake
 Erie's entire coastal  front."  According to D.L.  Anthony who wrote in


                                    66

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1922, the fishing  industry reached its zenith about 1854.  However the
noticeable disappearance of  herring did  not  begin  until  1889-90 while
whitefish and catfish declined after 1880.   Whether these  declines were
associated  with the  purported decline in water quality at about that time is
debatable.

WATER QUALITY AND SEDIMENT STUDIES

     Degradation  of water quality before 1900 is further evidenced when
Herbert S.  Jenning, in his  study of the algae of western  Lake Erie,
remarked that the surface of the  west end  was covered by a green layer.
He  certainly referred to a "bloom", and one which was much more exten-
sive than that  reported  off Toledo in 1859.   Tiffany discussed the occur-
rence of blooms during the  1920's while  the  author saw  a bloom of blue-
green algae that extended over the entire west end of the lake in 1933.
Recent years have seen periodic occurrences of blooms; some more,  some
less intense  and extensive.   The  latest  of great extent occurred  during the
summer of  1970.

     The pre- or early 1900 studies that involved water quality  in Lake
Erie were  either  localized,  for short periods, or limited mostly to obser-
vations  that concerned taxonomy.   Quantitative data are scarce.

     History of water quality in  Lake Erie  during the  past three quarters
of a century really  begins with the study by Stillman Wright and his
associates,  L.H.  Tiffany, and Wilbur M.  Tidd between 1926 and 1930.
No  comprehensive survey of the  physical, chemical,  and  biological condi-
tions had  been made prior to that study.

     The  first sediment study was made by  Moseley in 1904.  His work,
in conjunction  with observations  made in 1850, and with our present know-
ledge, lead to an estimated 3  fold increase in sedimentation rate during
the past century.   The  fact that  Lake Erie,  in 1922, had a two  year  avei—
age  of 2,2OO  mg/nrv^ dry organic  matter as contrasted  to  an oligotrophic
lake in  Wisconsin having an  average of  880 mg/m^ for the same period
accentuates the increase.  This  increase had had a pronounced effect on
oxygen  demand in the Lake.   Wright found oxygen depletion during three
seasons to be  generally of minor importance.  Today  its  depletion in the
western and  central basins where zero  levels have been observed frequently
since 1961 is a major concern.   One of the most quantitative measures of
water quality degradation in  Lake  Erie  since the turn  of the century has
been the increase in the 0% depletion  rate in the  hypo-limnion of the cen-
tral basin.   This is estimated to have been  about 3 percent  per  year dur-
ing the  past twenty  years.
                                    67

-------
      The  concentration of total dissolved solids, a gross indication of
 water quality,  has increased significantly from  133 mg/l to 198/mg/l dur-
 ing  the past half century.  Historical  data  point to marked increases of
 chemicals occurring in the Lake  since 1910.  There  are no historic data
 on total loading of phosphorous in earlier years, but some evidence exists
 that soluble reactive  phosphorous levels increased by four  times between
 1942 and 1967.  This  is  understandable when one  considers that  only 16
 percent of the  P entering Lake Erie leaves through the outlet.   Total
 nitrogen,  another  serious water quality  degrading  factor, increased three
 fold between  1930 and 1958, while a five fold  increase  in open lake
 ammonia occurred  during the same  period,  and a thirteen  fold increase
 in the latter  from  1942 to 1968.  Chloride  concentration at 6  ppm  in 190O
 stood at 25.6  ppm  in  1963,  while sulfate at 12 ppm in  1900 reached 23
 ppm in 1960,  of which 11 ppm  of the  latter had occurred in the  last thirty
 years.

     Concentrations of Si, Al,  K,  Na and  Mg  have not  changed appreciably
 since 1850 as evidenced by studies of cores.   However, Hg, Pb, Zn,  Cd,
 Cu, and organic C, N, P have all  increased due to loading in  the  lake
 since 1850.   In general,  loading of  mercury since  1950 has been extremely
 critical for water quality.  Current loadings of organic  carbon to the
 eastern basin  is estimated to be five times  that of colonial times,  with
 the 0  depletion rate increasing.

 SUMMARY

     The history of Lake  Erie, and especially  that of the  western  basin,
 has  been  one of eutrophication and degradation  of water  quality throughout
 its existence.   It was  the most productive of the Great  Lakes and  probably
 was mesotropic because of its shallow basin even  before its shores were
 invaded by Europeans.  Data indicate major increases in loading began a
 few years  prior to  1940,  with loadings continuing to increase since.  The
years during and immediately following World  War  II were  particularly
 critical because of increased industrial production with  attendant  increases
 in waste disposal. If Cladophora is an indication of degradation (which  may
or may not be true),  then observations by fishermen  as well  as others, of
 increases in Cladophora along shore lines during the  late 1940's  tend to
support degraded  water quality.

     Some historical  data however,  indicate that marked increases in
chemicals  occurred after  1910.   The chemicals, if the  I.J.C. report of
 1913 is accepted, were not industrial pollutants as that  report stated;
these types were  not in sufficient quantities  to affect  water  use.  They
must have  been domestic  and agricultural related.
                                    68

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     The question is not,  has water quality in Lake  Erie  changed,  but
rather, how much degradation has occurred since Lake  Erie was first
seen by  European travelers?   The historic fact is that Lake  Erie water
not only  has changed, but has changed drastically.  Furthermore, the
change in water quality accelerated once Europeans invaded the  lake and
its  environs.

REFERENCES

Beeton,  Alfred M.  1965.  Eutrophication  of the St. Lawrence Great
    Lakes.   Limnol.   Oceanogr.   10(2): 240-254.

Britt,  N. Wilson, James T.  Addis and Ronald Engel.   1973.  Limnologi-
    cal studies of the Island  Area of Western  Lake Erie.   Bull. Ohio
    Biol. Sur. (N.  Ser.)  4(3): 1-85.

Burns, N.M.   1976.  Temperature, oxygen, and nutrient  distribution pat-
    terns in Lake Erie,  1970.   J.  Fish.  Res.  Bd.  Can.  Special Issue.
    33(3):485-511.

Burns, N.M.   1976.  Oxygen depletion in  the  central and eastern basins
    of Lake Erie,  1970.   J.  Fish. Res. Bd.  Can. Special  Issue.  33(3):
    512-519.

Burns, N.M.   1976.  Nutrient budgets for Lake Erie.   J. Fish. Res.  Bd,
    Can. Special  Issue.  33(3):52O-536.

Burns, N.M.,  J.M.  Jaquet,  A.L.W. Kemp, D.C.L. Lam,  J.H. Leach,
    M. Munawar, T.J.  Simons,  P.G. Sly, R.L. Thomas,  N.H.F.  Wat-
    son  and J.D.H. Williams.   1976.   Processes within Lake Erie.   J.
    Fish.  Res.  Bd. Can.  Special  Issue.  33(3):639-643.

Burns, N.M.  and J.O. Nriagu.   1976.   Forms of iron  and manganese  in
    Lake Erie waters.   J. Fish.  Res.  Bd. Can.  Special Issue.  33(3):
    463-470.

Burns, N.M.,  J.D.H. Williams, J.M.  Jaquet,  A.W.L. Kemp, and D.C.
    L. Lam.   1976.  A phosphorous budget for Lake Erie. J.  Fish. Res.
    Bd.  Can.  Special Issue.  33(3):564-573.

International  Lake Erie Water Pollution Board  and the International Lake
    Ontario-St. Lawrence River Water  Pollution Board.   1969.  Report
    to the International Joint  Commission on the pollution  of Lake Erie,
    Lake Ontario and the international section  of the St. Lawrence River.
    Vol.   1 - Summary.  U.S. Govnt. Printing Office.  150 p.
                                  69

-------
Kemp,  A.W.L., R.L. Thomas, C.I.  Dell, and J.M. Jaquet.  1976.
    Cultural impact on the geochemistry  of sediments  in Lake Erie.  j.
    Fish  Res. Bd. Can.  Special Issue.  33(3)440-462.

Lam, D.C.L.  and J.M.  Jaquet.   1976.   Computations of physical  trans-
    port and regeneration of phosphorous in Lake  Erie,  fall 1970.   J.
    Fish.  Res. Bd. Can. Special Issue.   33(3):550-563.

Ongley, E.D.   1976.   Sediment yields and nutrient loadings from Cana-
    dian watersheds tributary to  Lake Erie: an overview.   J.  Fish.  Res.
    Bd. Can.  Special Issue.  33(3):471-484.

Taft,  Clarence E.  and W.  Jack Kishler,  1973.  Cladophora as related to
    pollution and eutrophication in western  Lake Erie.   Project completion
    report No.  332 x, 339 x.  U.S. Dept. Interior.  State of Ohio "Water
    Resources Center.  The Ohio State  University, Columbus.

Thomas, R.L. and J.M.  Jaquet.  1976.  Mercury in the surficial  sedi-
    ments of  Lake Erie.   J.  Fish.  Res.  Bd.  Can. Special Issue.   33(3)•
    404-412.

Thomas, R.L., J.  M. Jaquet and A.L.W. Kemp.   1976.   Surficial sedi-
    ments of  Lake Erie.   J.  Fish.  Res.  Bd.  Can. Special Issue.   33(3)-
    385-403.
                                   70

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                             SECTION 3

        OXYGEN DEPLETION AND ANOXIA IN THE  CENTRAL
        AND WESTERN  BASINS OF LAKE ERIE,  1973 - 1975

            John E.  Zapotosky  and  Charles E.  Herdendorf
                 Center for Lake  Erie Area Research
                       The Ohio State  University
INTRODUCTION

      From spring until fall turnover,  the  central and  western basins of
Lake  Erie show  a steady  decline in the concentration of dissolved oxy-
gen (Figures 24-27).  These changes  are initially a  change in the solu-
bility of dissolved oxygen due to warming of the water column.  The
central basin,  because of its middle latitude and moderate depth, strat-
ifies  into a thick epilimnion (15-17  m) relative  to the hypolimnion (4-
8 m).  The intervening  mesolimnion (thermocline)  retards mixing of
dissolved substances between the adjacent layers.  In  1974 and 1975
the hypolimnetic concentration  of dissolved oxygen  in the  central basin
diminished from a basin average of 80-85  percent  saturation  in early
June  to  12-29  percent by  early September (Tables 14-16).  A hypolim-
netic  saturation  of three percent was  estimated for early September
1973  (Table 14).   Thereafter,  with  the onset of fall  turnover, bottom
oxygen values  increased (Figures 28-29).

DEPLETION RATES

Central  Basin  Oxygen Depletion

      The steady depletion of dissolved oxygen within the hypolimnion of
the central basin was due to bacterial oxidation or organic material (88
percent  of depletion  rate  in 1970) and the  oxidation of reduced metallic
species  (12 percent of depletion rate  in  1970,  Burns and Ross 1972).
However, the  magnitude of the  depletion rate in this basin can be
masked  by any of several events, these  include:

      1)  Volumetric changes of the hypolimnion caused  by the
          loss or gain of water, including  dissolved  oxygen to
          or from the overlying mesolimnion.
                                   71

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                                                     BOTTOM OISSOIVED OXVGEN
                                                    CRUISE 1 MAR IB - APR 25,1975
                                                      Contour ml«rvol:Q5ppm
Figure  24.   Bottom dissolved  oxygen,  cruise  1,  March  18-
               April 25,  1975.
                                                     BOTTOM DSSOLVED OXVGEN
                                                    CRUISE 2 JUN 2 - JUN 19 ,1975
                                                       Contour Intorvol: I ppm
 Figure 25.
Bottom dissolved oxygen,  cruise 2,  June 2-
June 19,  1975.
                                    72

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         I        I
    20   0 |  20   40  «p  _ K>
         KILOMETERS
                                                     BOTTOM DISSOLVED OXYGEN
                                                    CRUISE 3 JULI3 - JUL 24, 1975
                                                       Contour Inttrvol: 1 pom
 Figure  26.   Bottom  dissolved  oxygen,  cruise  3,  July  13-
                July 24,  1975.
                                                     BOTTOM DISSOLVED OXYGEN
                                                    CRUISE 4 AUG 27 - SEPT 7, I975
                                                      Contour IMtrvor. 1 ppm
                                                    * 5 OOfi Eorlitr This Site Wo>
                                                      Br»fly Anoiic
Figure 27.   Bottom  dissolved oxygen, cruise 4,  August 27-
               September 7,  1975.
                                    73

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 TABLE 14.   SUMMARY OF 1973 HYPOLIMNETIC
SURVEYS OF  THE CENTRAL BASIN  OF LAKE  ERIE
Cruise
1
2
3
4
5
6
7

8
g
Dates
6/30-7/2
7/17-7/21
7/25-7/28
8/7-8/1 1
8/29-9/4
9/23-9/29
10/14-
10/24
11/7-
11/15
12/4
Area
(km2)
Inc
12,883
Inc
12,962
11,829
3,660
Volume
(km3)
omplete C
61.6
wnplete C
60.8
47.1
11.3
Ave.
Thick.
(m)
)ata
4.8
ata
4.7
4.0
3.1
Unstratlfied

L
L

Jnstratifte
Jnstratirie

d
d
Total
Heat
(kcalxlO12)

636.1

721.6
556.8
151 .3




Ave.
Temp.
(°C)

10.3

11.9
11.8
13.3




Total
•°2 «
(kgO2x1Q6)

30O.3

167.0
14.9
12.3




Ave. O2
Cone.
(ppm)

4.9

2.7
0.3
1.1




Ave . Temp .
Grad . Across
Meso.(°Cm~1)

5.2

6.7
5.6
2.9




Ave. O2 Meso.
Across Meso.
(gOam"4)

1.7

2.4
3.0
4.0





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                     TABLE  15.   SUMMARY  OF 1974  HYPOLIMNETIC
                   SURVEYS OF  THE CENTRAL  BASIN  OF LAKE  ERIE
Cruise
1
2
3
4
5
6
7
8*
9
1O
11
Dates
4/7-4/17
4/25-5/4
5/14-5/24
6/1-6/10
6/3Q-7/7
7/26-8/6
8/12-8/19
8/26-9/7
9/24-9/27
10/21-
11/1

Area
(km2)
Volume
Unstratlflee
I
Unstrattflec
J
14,819
11,860
12,538
11,698
10,556
U
I
U
U
Ave.
Thick
(m)
J
Tstratlfled
91.9
49.1
62.8
50.6
48.8
6.2
4.1
5.0
4.3
4.6
nstratlfled
nstratlflec
I
I
nstratiflec
I
I
Total
Heat
(kcalxlO12)


794.7
524.4
800.6
687.2
673.2



Ave.
Temp .


8.7
10. 7
12.8
13.6
13.8



Total
°2 «
(kgOpXlO6)


91O.8
352.1
196.6
104.6
34.6



Ave . O_
Cone.
(ppm)


9.9
7.2
3.1
2.1
0.7



Avo . Temp .
Grad . Across
Meso. (°Cm~1)


1.9
6.0
5.6
5.5
7.4



Ave. O2 Meso.
Across Meso .
(gOgn-T4)


1.4
2.4
3.4
3.6
6.O



*  Turnover occurred during Cruise 8.

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 TABLE 16.   SUMMARY OF 1975 HYPOLIMNETIC
SURVEYS OF  THE CENTRAL  BASIN  OF LAKE  ERIE
Cruise
1
2
3
4
5
6
Dates
3/27-4/25
6/9-6/16
7/13-7/20
8/27-9/5
9/29-1 O/6
12/2-
12/14
Area
(km2)
I
13,680
13,385
9,6OO
Volume
(km3)
Jnstratlfle
104.7
90. 5
66.1
Ave.
Thick.
(m)
d
7.7
6.8
6.9
Unstratiried
I
Unstratlfle
I
d
Total
Heat
(kcalxlO12)

684. 0
708.7
673.7


Ave.
Temp.
C°C)

6.5
7.8
10. 2


Total
•°2 «
(kgO2x106)

1047.7
697.7
216.6


Ave. 02
Cone.
(ppm)

10.0
7.7
3.3


Ave . Temp .
Grad . Across
Meso. (°Cm~1)

4.0
6.0
6.5


Ave. O2 Meso.
Across Meso.
(902m"4)

0.2
0.7
3.4



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                                                    BOTTOM DISSOLVED OXYSEN
                                                   CRUISES SEPT 27 -OCT 6,1975
                                                     Contour Inttrvol: 1 ppm
Figure 28.   Bottom dissolved  oxygen,  cruise  5, September 27-
               October 6,  1975.
                                                   BOTTOM DISSOLVED OXYGEN
                                                  CRUISE 6 DEC2-DECIO, I9'5
                                                     Contour Inttrvol: 1 ppm
Figure  29.   Bottom  dissolved oxygen,  cruise 6,  December  2-
               December 10,  1975.
                                   77

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    2)  Exchange of water between  the mesotimnion and  hypolimnion,
        including  dissolved oxygen,  without  volumetric changes in
        either layer.

    3)  Entrainment of adjacent basin and tributary water masses
        within the hypolimnion, including dissolved oxygen.

    Temperature  profiles (Figures 7-8) show a seasonal lowering of
the thermocline at hypolimnetic volume  loss.  Estimated hypolimnetic
volumes (Figure  9) generally  follow this trend but fluctuate within  a
year or between years.  Additionally,  evidence of downwellings (Fig-
ures 10-11), upwelling (Figure 12) and entrainment of oxygenated waters
in the  southeast portion of the basin (Figures 13-14)  indicate  the central
basin hypolimnion  as  an occasionally open and dynamic system.

    Burns (1976) has proposed a  Mesolimnion Exchange  Model to more
accurately determine  the oxygen  depletion rate by  estimating  and cor-
recting for exchanges  with the hypolimnion.   A sample calculation is
presented  in Table 4.   Due to a  lack of accurate estimates,  calculations
presented  here  neglect entrainment  of eastern basin waters.  Thus,
1973 and  1974 values presented in Table 5  are somewhat conservative
(1975 oxygen contours show no evidence  of  this phenomenon).
    Average volumetric  rates of 0.12,  0.13, and 0.10 g
and average areal rates  of 0.53,  0.60 and  0.67 g O2m~2day~1  were
calculated for  1973,  1974,  and  1975 respectively  (estimates of  1973
rates are not based  on the entrie stratification period).   The apparent
improvement experienced in 1975 must  be viewed critically, as a simple
student T-test shows no difference in 1973 - 1975 depletion  rates that
are detectable by statistical means.

    Burns (1976) suggests the following  relationship:

                         °v = Kw + Ks/d

where,   Ov = volumetric oxygen delpletion rate

          KW = water column oxygen demand

          K  = sediment oxygen demand
            O

          d  =  mean hypolimnetic depth
                                     78

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                 Temperature (°C)
          o°
                            10°
                                     15°
                                              20°
                                                       25°
     •P  10

     ^y

     4_1
     a

     Q  is
        20
 Figure 30.   Temperature  profile at station no. 73 for May-

              October   1974.


                 Temperature (°C)
     £   ,o-
     a
     0)
     Q
Figure  31.   Temperature profile at station no. 73  for  April-

             December  1975.
                              79

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CRUISE

   100 r—
    90
    80
                         4      5      678
    70
UJ
O
O  60
UJ



O  5O
    40
K   30

U
o
oc
UJ   20
    10 -
km'
                                    n
                                         n
n
        JUL
              I973
                               I974
                                                                              I975
EpHlmnion
                                                                                             Mesollmnion
                                                                                            I Hypolinmlon
                                                                                 AUG    SEPT
          Figure 32.   Volume comparison for  stratification layers  in  the

                        central basin of Lake  Erie  1973-1975.

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CO
   PORT STANLEY, ONT.
                    Figure 33.  Thermal structure of Lake Erie (°C), profile  H,
                                cruise 5, September 3,  1973.

-------
      PORT CREWE, ONT.


              41
       	1	
42
 i
43
 i
45
CLEVELAND, OHIO


         44
oo
ro
   22-
                     Figure 34.  Thermal structure of Lake  Erie  (°C), profile  F,

                                 cruise 1, June 30-July 1, 1973.

-------
oo
oo
   POINT AUX PINS, ONT.
FAIRPORT, OHIO
                     Figure 35.   Thermal structure of  Lake Erie (°C), profile G,

                                  cruise 4, August  9,  1973.

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     I        I
20   0   20   40  60   «O
I	I	1	1	1	1	1	I I  I
      KILOMETERS
                                                BOTTOM DISSOLVED OXYGEN

                                               CRUISE 4 AUG.7- AUG. II , 1973
                                                 Contour Interval: I ppm
 Figure  36.   Bottom dissolved oxygen,  cruise  4,

                August 7-August 11,  1973.
                                                BOTTOM DISSOLVED OXYGEN

                                               CRUISE 6 JULY2S-AUS6 I974
                                                 Contour Interval: 1 ppm
 Figure 37.   Bottom dissolved oxygen,  cruise 6,

                July  26-August 6,  1974.
                              84

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      TABLE  17.   SAMPLE CALCULATION FOR MESOLIMNION
      EXCHANGE  MODEL FOR LAKE  ERIE HYPOLIMNION OXY-
         GEN DEPLETION  FOR JULY 16-SEPTEMBER 1, 1975
1 .  Hypolimnetic area (km2)  and volume (km3):
                        Area     Volume
          Cruise 3  =  13,385      90.49
          Cruise 4  =   9,599      66.07
                 Mean  11,492      78.28
             Decrease  3786.0      24.42

2.  Mean temperature (°C) and  dissolved oxygen (g Q2 rn~ ) of upper
    hypo limn ion:
                     Temperature  Oxygen
          Cruise 3  =   7.98        7.39
          Cruise 4  =  11 .21        3.55
                Mean     4.60°C     5.47 g O2  m

3.  Hypolimnetic losses during volume decrease:

          Heat                                12
            9.60°C x 24.42 km   = 234.43 x 10   kcal.

          oxygen         o            o               6
            5.47g Og rn   x 24.42 km0 =  133.58  x 10  kg O^

                                   12
4.  Heat  budget of hypolimnion (x10   kcal)i

          Cruise 3  =  708.67   (observed)
          Cruise 3-4= -234.43   (calculated loss)
          Cruise 4  =  474.24   (anticipated)
          Cruise 4  =  673.66   (observed)
          d iscrepancy   199.42

          Note:  the  above considers that heat loss to sediments and
          heat conducted into the hypolimnion by thermal conduction to
          be insignificant  when compared to the  above values and
          roughly equal,  therefore  cancelling each other.  (Burns and
          Ross,  1972).   The discrepancy (anticipated-observed) is
          assumed to be the  result of water exchanged with  the meso-
          limnion   (=  exchange heat).
                                                            (continued)
                                   85

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                          TABLE 17  (continued)


 5.   Mean temperature (°C m~1) and dissolved oxygen (g C>2 rn~  )
     gradients  of the mesolimnion:
                     Temperature Oxygen
           Cruise 3 "^  6.06     0.69
           Cruise 4  =  6.46     3.36
               Mean     6.26     2.03

 6.   Dissolved  oxygen added to hypolimnion  by exchanges with the meso-
     limnion:
                     -4
          2'03 g - 01.!    x 199.42 x 106 m3 °C =  64.67 x 106  a O
          6.26°C  m                                              ~  2

 7.   Dissolved  oxygen budget (x10 kg O2)  of hypolimnion:

          Cruise 3   =  697.72  (observed)
          Cruise 3-4  = -133.58  (calculated  loss)
          Cruise 3-4  = -f 64.67  (calculated  gain)
          Cruise 4   =  628.81  (anticipated)
          Cruise 4   =  216.52  (observed)
          discrepancy    412.29

          Note:  discrepancy is assumed  to be the result of internal
          oxygen depletion.

8.  Areal depletion rate:

          412.29 x 106 kg O         -|                      r>      1
          11,492    ^ - 2   X  -=0'80   9 °2 m   day
          *  Days between the midpoint dates of Cruise  3  and 4.
9.  Volumetric depletion rate:

                     £>
          412.29 x  10   kg  Op       1       _                 _3
           78.28              X   45~days ~   °'12  g  °2 m   da^
                                  86

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                     TABLE 18.  HYPOLIMNETIC OXYGEN DEPLETION RATES

                        IN THE CENTRAL BASIN  OF  LAKE ERIE (1973-1975)
Cruise
1973
2-4
4-5
Mean
1974
4-5
5-6
6-7
7-8
Mean
1975
2-3
3-4
Mean
Intercruise
Period (Days)
21
23
26.5
27.5
15
16.5

34
45
Mesolimnion
Exchange Model
Area
-0.60
-0.46
-0.53=1=0.10
-0.66
-0.85
-0.46
-0.42
-0.60=b 0.20

-0.53
-0.80
-0.67=t 0.19
Volumetric
-0.13
-0.10
-0.12±:0.02
-0.13
-0.19
-0.10
-0.09
-0.13 =to .05

-0.07
-0.12
-0.10 -±0.04
Net Volumetric
Depletion Rate
-0.10
-0.10
-0.10 =!=0.01
-0.10
-0.15
-0.07
-0.07
-0.10 zh 0 . 04

-0.07
-O.1O
-0.09 =t0.02
00
                          —2   —1
       Areal Rates: g OQ m day  .
                                /3     j

       Volumetric Rates: g Og m day"1.

-------
 Based on the small  probability that an  apparent improvement did occur,
 several  explanations are  possible using this relationship.  Although
 Blanton  and Winklhofer (1972) failed to note dissolved oxygen fluctuations
 in the water column due  solely to the presence of algae, Lucas and
 Thomas (1972)  noted diurnal  fluctuations in the sediment oxygen demand
 in the central  basin.  Oxygen,  produced by algae offset the  sediment
 oxygen demand rate by as much as 0.6 -  0.7 gm O2'day~1.  A mean
 corrected chlorophyll a value for the hypolimnion in  1975 was 92 percent
 greater  than recorded  in  1974 (Fay,  1976).

      The sediment-water interface of the  central basin  has  been cited
 as the major site  of bacterial activity (Menon et  al.  1972).   The over-
 all  volumetric depletion rate  includes oxygen  depleted at this interface
 plus the oxygen consumed or produced  in the hypolimnetic water column.
 Therefore,  as the thickness of the hypolimnion becomes small, the nor-
 mally  larger sediment oxygen demand plays a larger role in determining
 the overall  rate.  The average thickness of the hypolimnion during strat-
 ification was 7.1 m in 1975 and only 4.9 in 1974.  Thus, an apparent
 improvement in the  volumetric  depletion rate may only reflect the in-
 creased  hypolimnetic thickness.

      The volumetric depletion rate of the central basin  has been sug-
 gested as an indicator of the trophic  state of the  lake (Dobson and
 Gilbertson,  1972).   Depletion rate values have reached and oscillated
 around a value  of  0.12 -  0.13 g C>2*m~3*day-1, since the early 1960's
 (Figure  38).  However, to determine a genuine improvement in the
 depletion rate (due to the influence and vagarity of  meteorological  con-
 ditions), Burns (1976) stated  that this rate  must be measured to an ac-
 curacy of + 3 percent for five consecutive years (assuming an annual
decrease of 0.0025 g O2-m-3-day~1 .year'1).   Thus,  no improvement
 in the  trophic state of Lake Erie,  using the volumetric depletion  rate
has been discerned in the first half of the 1970's.  Present  areal  def-
 icit rates place  the central basin in  the eutrophic state (i.e. >0.55 g
O2'm 2*day~ ,  Hutchinson  1957).

Western Basin Oxygen  Depletion

     Due to the transitory  nature  of  stratification in  the western basin,
measures of an  oxygen deficit rate were not possible.  Data collected
in 1973 and 1975 indicate that the  sediment oxygen demand  in this basin
remains  high and continues to become depleted of oxygen under appro-
priate  conditions.
                                   88

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                                       OXYGEN DEPLETION RATE
g 02 m"3 DAY"1
00
UD
               (Q
                C

                (D

                GO
                00
              (D (D

-------
ANOXIA

Factors  Influencing Anoxia

     Over the last 45  years, the average oxygen concentration  of the
bottom waters of the central basin have  consistently been found to be
approximately 10 ppm  at the onset of stratification.   Based on  this
fact and  a stratification period greater than  100 days, Dobson and Gil-
bertson (1972) suggest a critical depletion  rate  of 0.10 g«02'm~3*day~1
as causing areas of the basin to become anoxic.  This value  was
exceeded  in  1961,  however,  the  central basin may have  experienced
varying degrees  of oxygen  deficiencies since 1929.

     Carr (1962),  in summarizing the available  data  1928 -  1961,  con-
sidered dissolved oxygen concentrations of less than 1.0 ppm as indica-
tive  of severe oxygen depletion.   Latsr, in reporting hypolimnetic con-
ditions in 1964,  the Federal Water  Pollution Control Administration
(1968)  used a value of 2.0 ppm or less to indicate  an oxygen deficit
zone of 7500  km   in the central  basin.   However, Piersall  and Morti-
mer (1939) noted ferrous  iron  (regenerated  form) appeared  in the sedi-
ments  of  Blelham  Tarn at  oxygen concentrations of 0.5 ppm,  while
Burns  and Ross  (1972) found soluble reactive phosphorous  regenerated
in the  central  basin at about the same value.   Using  values obtained
1.0 m  above  the bottom (this horizon was  selected  to  prevent disturbing
bottom sediments) the  regeneration of soluble reactive phosphorous  was
observed  at values  between 0.25 and  0.50  ppm  oxygen.  Therefore,  a
value a 0.50  ppm  has  been selected  as  defining  anoxic conditions.
This conservative  value, considering  the sampling horizon,  probably
represents a  higher value than that experienced  at the sediment-water
interface.

     The  size of the anoxic  area is  logically based on several  inter-
related factors,  (1) oxygen depletion rate,  (2) stratification  character-
istics (period of stratification, initial dissolved oxygen content, hypo-
limnetic  exchanges  and horizontal movements of bottom waters) and (3)
meterological  conditions.   Because of a  lack of data early in 1973,
comparisons  will be limited primarily to the 1974 and 1975 field years.

     Average  basin  concentrations of 0.3, 0.7 and 3.3 ppm were
recorded in  late August to early September  of  1973,  1974 and 1975,
                                    90

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 respectively.  This was also found to  be the  time of maximum anoxia
 and  probably represented a stratification  period of less than 100 days.
 Although the average  oxygen concentrations were  about equal in June
 of 1974 and 1975 (9.9 and 10.0 ppm, respectively),  the total  mass of
 dissolved oxygen in the hypolimnion  was initially  137 x  10^ kg O2
 greater in  1975,  and  at turnover,  it was approximately 182 x  106  kg  O2
 (Table 19).  The difference  in oxygen  content at the onset of  stratifica-
 tion can apparently account for 98 percent of the  adjusted  difference
 observed  between the two years,  while  the difference due to losses by
 physical processes  amounted to less than 1 percent.  Thus, oxygen re-
 moval by biological and chemical means was  about  equal at 8.25 x 106
 kg O2'day~1 in  1974  and  8.29  x 106 kg O2'day~1  in 1975.

      Hutchinson (1957) cited the importance of  both exposure and  windi-
 ness in determining the thickness of the epilimnion.  Thus, wind stress
 (therefore wind velocity) and direction are important variables in the
 amount of mixing (as indicated  by  hypolimnetic  warming) between the
 epilimnion and hypolimnion  and the relative thickness of  both layers.
 In June 1975,  the hypolimnion  was approximately  1.5 m  thicker and
 2.25°C colder than values measured in 1974.  This relationship re-
 mained throughout the season with 1975 values reaching turnover at
 2.3  m thicker and 3.6°C  cooler than 1974 estimates (Figures 30 and  31).
 The initial  oxygen content has  been suggested as  a  possible critical
 factor in  anoxia.  However, had meteorological conditions  been similar
 to 1974, a  greater  amount of oxygen would have been removed by  phys-
 ical means resulting  in a thinner and warmer hypolimnion.

      Over  the stratified period May through September the persistence
 (Figure 39) and  mean monthly  resultant wind velocities for 1975  are
 lower, except  for the month of July,  than values  recorded in  1973 and
 1974 (Figure 40).  The percentage of southwest and  northeast winds
 (axis of longest  fetch) greater  than  10  mph was 27  percent lower  during
 the  1975 stratified period than resultant velocities in 1973  and  1974.
 Average velocities neglecting direction in 1975 were lower over the
 period May through July than the comparable  period in 1973 and 1974.
 Banks (1975) suggested  a  value of  12.7 mph  as  the  dividing line  be-
tween strong and light winds.  Of the years  examined, only May 1975
 had  markedly fewer number  of days  with  an  average daily  wind velo-
 city greater than 12 mph  (Figure 41).   Indeed,  the  stratified period in
 1975 experienced three  storms with velocities greater than 24  mph,
while none occurred in  1974.   As evidenced  by  volume estimates and
temperature profiles,  these storms failed to mix  the thermocline to a
depth equal to  that recorded in 1974.  Hunt (1954) observed for a
given wind speed that the shear stress  varied as  a  function of the  dif-
ference between  the air temperature (Ta) and the  surface water tem-
                                   91

-------
                    TABLE 19.  HYPOLIMNETIC OXYGEN CENTRAL BASIN OF LAKE

                               ERIE 1974 AND  1975 VALUES  = kg O2 x 106


O cone, at onset of
stratification
Net O loss due to
physical processes
O2 depleted by biological*
and chemical processes
O2 remaining at turnover
Adjustments
O2 cone, diff. 1975-1 974 at
onset of turnover

1974
910.8 (7 June)
174.7
701 .4 (85 days)
34.7
0
34.7

34.7

1975
1047.7 (12 June)
176.3*
6 54 .'9 (79 days)
216.5
-42.8**
173.7***
136.9
36.8
Difference
(1975-1974)
-1-136.9
+ 1 .6

181.8
- 42.8**
139.0
136.9
4 2.1
ro
                                                      R        —1
        Op removal  at average season rate of 8.25 x 10 kg O2day    in 1974 and 8.29 x



         106kg O2-day~1  in 1975.



        6 days at 11  AN, Average  1975,  June removal rate of 7.13 x 106kgO2day~  .



     ***Adjusted 1975 O2 remaining at turnover.
**

-------
      60
      50
   o
   g  40
   a.
   00
   oo
      30
      20
           sw
         197!
           NW
                  SW
                        SW
          APR  I  MAY I JUNE {  JULY  |  AUG  |  SEPT f OCT  | NOV)
Figure 39.  Monthly  wind persistence for dominant direction
             at  Long  Point,  Ontario for  1974 and 1975.
      10
  o
  00
  UJ
                  MEAN MONTHLY RESULTANT
                     WIND VELOCITIES
                                                      •/••OI974
ao


"
10
  LU
                           MEAN MONTHLY
                          WIND VELOCITIES
                                                       1974
                                                   .AI973
          APR  |  MAY  |  JUNE |  JULY  |  AUG |  SEPT |  OCT  | NOV  |
  Figure  40.   Average  and resultant winds at  Long Point,
               Ontario for 1973-1975.
                               93

-------
                           LONG POINT WINDS
                     APR MAT JUNE JULY AUC SEPT  OCT ' NOV DEC
                            LONG POINT WINDS
                     AP8 MAT 'JUNE ' JULY AUG 'SEPT ' OCT ' NOV 'DEC
                        LONG POINT WINDS
                     APR ' HAY ' JUNE ' JULY ' AUG ' SEPT ' OCT ' NOV DEC
  Figure 41.   Long  Point winds  for 1973, 1974 and 1975.
1
 "K" stands for  knots.
                             94

-------
perature (Tw).   Although surface water temperatures were higher in
1975, the monthly average temperature difference  for the  stratified sea-
son, as  measured at  Marblehead  (Table  20),  was smaller  in  1975 with
all  three years indicating a stable to neutral  atmosphere for  the  stra-
tified season (Figure  42).   Since the given time frame  is  lengthy,
the role of  the  aii—water temperature  difference is somewhat inconclu-
sive as to its effect  on the 1974-75  hypolimnia.

Central Basin Anoxia
      The first comprehensive survey of the central basin (June-Septem-
ber) was  performed  in  1929  by Fish et al. (1960).   The  lowest  recor-
ded oxygen  value was 4.4  ppm  at a  station 25 miles  northwest of
Cleveland,  Ohio.  This value was  noted about mid-August,  while the
next survey did  not occur  until mid-September (temperature contours
indicate turnover had occurred  by  this  time).   Stratification in this.
basin usually persists  from  late May or early June to early or  mid-
September, depending  on meteorological conditions.  The time of maxi-
mum  areal  extent of anoxia  was found to be late August to early Sep-
tember in 1973-1975.   Thus, Fish et al. (1960) had probably  missed
the ideal  time for perception of anoxic  conditions.  Also water samples
taken 1.0m above the  bottom were  not always taken below the meta-
limnion.  Fish's (1929) study, as  in many subsequent surveys, failed
to sample the  southwest portion of the  basin.   This area, roughly
bounded by the triangle formed by Sandusky, Ohio  to  Lorain,  Ohio to
Pelee Point, Ontario,  is historically the most consistent area of
anoxia, with anoxia usually starting  in  this area  and  spreading to other
portions of the basin.   In  1973-1974, it was  found  also  to be  an area
with a thin and transitory  hypolimnion.   In August  1930, Wright (1955)
recorded  an oxygen value  of 0.8 ppm at a station 1.1 km east of
Marblehead Light.  However,  more  eastward stations sampled on the
same day were well oxygenated.  This  reading, although on the
extreme western edge  of the central basin, probably  represented a
transitory situation such as  that experienced  in the western  basin.
Studies by  the  University  of Western Ontario failed to show any anoxic
conditions during the  period  1947-1953,  and  low values of 2.1  and 2.0
ppm were noted in mid-lake and off Rondeau  Harbor,  Ontario  (Powers
1960).  In  1959  and  196O,  federal,  provincial,  state and university organ-
izations participated in determining the extent of low dissolved oxygen wa-
ters  in the central basin (Beeton 1963).  These studies revealed an  area
of 3,6OO  km2  in  1959  and  1,660 km2 in 1960 with  hypolimnetic oxygen
                                   95

-------
                    TABLE 20.  MONTHLY AVERAGE AIR-WATER TEMPERATURE

                      DIFFERENCE (°C) - MARBLEHEAD AND  PUT-IN-BAY, OHIO
vo
en

April
May
June
July
August
September
1973
+ 1 .6
+0.9
+5.6
-0.9
-0.8
+0.1
1974
+2.6
+0.6
+2.7
+0.3
-0.8
-2.3
1975
+0.5
+4.5
+0.1
-2.1
-1 .1
+0.0

-------
             25°

             20°


              15°

              10°


               5°
                          MEAN MONTHLY AIR TEMPERATURE
          UJ
          Q_
                          MEAN MONTHLY WaTER TEMPERATURE
              25°


              20°


              15°


              10°


               5°
                   APR  |  MAY  |  JUNE |  JULY  |  AUG  |  SEPT |
          Figure 42.  Mean monthly water temperatures at
                       Marblehead,  Ohio  for  1973-1974.
     Note:  July-September,  1973 values estimated  from Put-in-Bay,
Ohio records.
                                  97

-------
 values  less than  1.0  ppm  (in 1959 the area  with less than 0.5  ppm oxy-
 gen was 780  km  ).   Subsequently,  every year sampled (Carr,  1962;
 Great Lakes  Institute,  1964,  1965;  Canada Centre  for  Inland Waters,
 unpublished data  1967-1970)  has shown anoxic areas, but due to sampling
 patterns, accurate estimates  of the areal extent of this  condition were
 not  possible.

      Burns and Ross (1972)  indicated an anoxic region (zero percent
 saturation) of about 6,600  km2  in  1970,  while in  1973 and 1974 maxi-
 mum areas of 11,270 and  10,250 km2 «0.5 ppm  dissolved  oxygen)
 were recorded.   However, in 1975, although the areal  depletion rate
 was at  the critical value of 0.10  g O2/m~3*day~1,  only about  2.5 per-
 cent (4OO km2)  of the basin became anoxic.   This indicates  the dramatic
 fluctuations (63.4 to 2.5 percent) that can occur in the anoxic area of
 the central  basin between  years.   An accurate comparison of the anoxic
 area is difficult and can be obscured  by station patterns, sampling
 times,  length of stratification,  meteorological effects and horizontal
 movements  of hypolimnetic waters.  Also, the transitory nature of
 anoxia  in the  southwestern portion of the basin  further  confuses the
 extent of oxygen-deficient  waters.

 Western Basin Anoxia
      Carr  et al. (1965) estimated that five days  of stratification were
required  in 1963 to reduce  oxygen concentration of portions of the west-
ern basin to 3.0 ppm,  whereas, 28 days were  needed in  1953.   During
a period of light winds, Britt (1955) reported an  oxygen concentration
of 0.1 ppm at a stratified station two  miles west of South Bass Island.
He  associated this observation with a large reduction in the  mayfly
(Hexagenia  sp.) population of this area.   Later, Britt et  al. (1968)
reported (for the same area) a  drop from 3.O to O.1  ppm (1O-15 cm
above the bottom) over the  five-day period  26 June to 1 July,  1966.
Two cruises (Figures 43-44), 10-12  July and 29-30 August,  in  1973
obtained values of  less than 3.0 ppm  for a sampling horizon 1.0 m
one meter above the bottom.  At these stratified sites, the dissolved
oxygen  concentration rapidly fell below 1.0 ppm as the sensor neared
the  bottom.  These areas of low oxygen were west and north of the
sites  sampled by Britt  (1953).   Additionally,  unusually  large quantities
of silica, ammonia and phosphorus were observed in  the  western basin
on 20-21  July  1975.   Although oxygen  values  ranged between 6 and  9 ppm
at the time of the  cruise,  the presence of these nutrients indicates a
probable regeneration due to a  prior anoxic condition.
                                   98

-------
   BOTTOM DISSOLVED OXYGEN
;;_CRUISE 1  JULY 10-12, 1973
    CONTOUR INTERVAL 1 PPM
   Figure  43.   Bottom  dissolved oxygen,  cruise  1,
                  July  10-12,  1973.
    iBOTTOM DISSOLVED OXYGEN
 .._[CRUISE 5  AUG. 29-30, 1973
     CONTOUR  INTERVAL 1 PPM
    Figure 44.   Bottom dissolved oxygen,  cruise 5,
                  August 20-30, 1973.
                             99

-------
 CONCLUSIONS

      From the  results of the 1973-1975 dissolved  oxygen surveys  of the
 central and western basins and a  review of historical surveys of these
 basins,  the following conclusions are  extracted:

      1.  The hypolimnion of the central basin is subject to
          relatively large exchanges with overlying and ad-
          jacent waters.

      2.  Depletion  rate calculations  must estimate and  cor-
          rect for fluxes with the  hypolimnion of the  eastern
          basin.

      3.  Areal  and volumetric depletion rates for  the central
          basin show no improvement  over the period 1973-
          1975.

      4.  The volumetric depletion rate has fluctuated around
          a value between 0.12-O.13 g O2/m~3*day~1  since
          the early  1960's and has not fallen below the "crit-
          ical rate" of 0.10 g O2/rrr3'day~1 since this time.

      5.   The central  basin can  be classes as eutrophic  based
          on the 1973-1975 areal  depletion rates.

      6.   Potentially large fluctuations (63.4-2.5 percent be-
          tween years)  in the areal extent of annoxia  eliminates
          this factor as  a criterion for judging the trophic
          state of the central basin.   The usefullness of  this
          criterion  is limited by lack  of accurate historical
          estimates, the difficulty  in determining the  maxi-
          mum extent, and the effects of meteorological
          conditions  limit.

      7.   Data for 1973 and  1975 indicate that bottom waters
          in the  western basin continue to become depleted of
          oxygen and experience  temporal anoxia.
                            DEFERENCES

Banks,  R.B.   1975.  Some features of wind  action on  shallow lakes.
      J. Environ. Eng.  Div.  A.S.C.E.  Iss. No. 1O1 (EE5).
                                  100

-------
Beeton, A.M.   1963.   Limnological  survey of Lake Erie, 1959 and  1960.
      Great Lakes Fishery Comrm. Tech.  Rept. No. 6.   32  p.

Blanton, J.6.  and R.A. Winklhofer.   1972.   Physical  processes affect-
      ing the hypolimnion of the  central basin of Lake  Erie.  p.  9-38
      in  Project Hypo, N.M. Burns  and C. Ross (eds).  CCIW Paper
      No. 6. USEPA Tech.  Rept.  TS-05-71-208-24.  182 p.

Britt,  N.W.  1955.   Stratification in western  Lake Erie in  summer  of
      1953;, Effects on the Hexaginia  (Ephemeroptera) population.   Ecol-
      ogy 36:239-244.

Britt,  N.W., E.J. Skoch,  and K.R. Smith.   1968.  Record low dis-
      solved oxygen  in  the island area of Lake Erie.   Ohio  J. Sci.
      68(3):175-179.

Burns, N.M.  1976.  Oxygen depletion in the  central and eastern
      basins of Lake Erie,  1970.  J.  Fish.  Fes. Bd.  Can.   33(3):512-
      519.

Burns, N.M. and C.  Ross.  1972.  Oxygen-nutrient relationships with-
      in the  central  basin of Lake Erie.  p. 85-119 ir\_ Project  Hypo,
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      Tech.  Rept. TS-05-71-208-24.  182 p.

Carr, J.F.  1962.   Dissolved oxygen in  Lake Erie, past and present.
      Pub.  No. 9.   Great Lakes Res. Div.,  Univ.  of  Mich.  p. 1-14.

Carr, J.F., V.C. Applegate and M. Keller.  1965.  A recent  occur-
      ence of thermal stratification and low dissolved oxygen in  wes-
      tern Lake  Erie.  Ohio J.  Sci.  65(6):319-327.

Dobson,  H.H.  and M.  Gllbertson.   1971.  Oxygen  depletion in the
      central basin of Lake  Erie,  1929 to 197O.   p. 3-8 _in  Project
      Hypo,  N.M. Burns and C. Ross (eds).   CCIW Paper  No.  6.
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Fay, L.A.  1976.   An investigation of corrected chlorophyll a and
      pheophytin a in Lake  Erie's  western and central  basin.  Ohio
      State M.S. Thesis.  Ohio State Univ.

 Federal Water  Pollution  Control Administration.  1968.   Lake Erie
      environmental summary: 1963-1964.  U.S.  Department of the
      Interior,  Great  Lakes Region  Publication.   170  p.
                                  101

-------
 Fish,  C.J. and Associates.   1960.   Limnological survey of eastern and
      central  Lake Erie,  1928-1929.   U.S.  Fish and Wildlife Serv.
      Spec.  Sci.  Rept. - Fish. No.  334.  198 p.

 Great  Lakes Institute,  Univ.  of Toronto.  1964.  Great  Lakes Insti-
      tute data record  1962 surveys,  part I:  Lake  Ontario  and  Lake
      Erie.   Rept. P.R. 23.   195 p.

 Great  Lakes Institute,  Univ.  of Toronto.  1965.  Great  Lakes Institute
      data record, 1963 surveys part I:  Lake Ontario, Lake Erie and
      Lake St. Clair.   Rept.  P.R. 23.   195 p.

 Hunt,  I.A.   1959.  Winds, wind set-ups,  and seiches on Lake Erie,
      part II.  U.S.  Army Corps  of  Eng., Lake  Survey,   58 p.

 Hutchinson, G.E.  1957.  A treatise on limnology, volume I.  J.
      Wiley and Sons,  Inc.   New York.   1015 p.

 Lucas,  A.M. and N.A. Thomas.  1972.   Sediment oxygen  demand  in
      Lake Erie's central basin, 1970.  p. 45-5O _tn_ Project Hypo,  N.
      M. Burns and C. Ross (eds).   CCIW Paper No. 6.   USEPA
      Tech. Rept. TS-05-71-208-24.   182 p.

 Menon, A.S., C.V.  Marion  and A.N. Miller.   1972.  Microbiological
      studies  related to oxygen depletion and  nutrient regeneration pro-
      cesses in Lake Erie's central  basin.   p.  71-84 _in_ Project Hypo,
      N.M.  Burns and  C. Ross (eds).  CCIW Paper NoT 6.  USEPA
      Tech. Rept. TS-05-71-208-24.   182 p.

 Pearsall, W.H. and  C.H. Mortimer.  1939.   Oxidation-reduction
      potentials in waterlogged soils, natural waters and muds.   J.
      Ecol.  27:483-501  .

 Powers, C.F., D.L. Jones , P.C.  Mundinger  and  J.C. Ayres.   1960.
      Application of data collected along  shore to conditions in Lake
      Erie.   Great Lakes Res.  Div.  U.  Mich.  Pub. No. 5.  p.  1-78.

Wright, S.   1955.  Limnological survey of western  Lake Erie.   U.S.
     Fish and Wildlife Serv.,  Spec. Sci. Rept.   Fish.  No.  139.
     341 p.
                                  102

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                             SECTION 4

 TRANSPARENCY, CONDUCTIVITY AND TEMPERATURE SURVEYS
     IN THE CENTRAL AND WESTERN  BASINS  OF  LAKE ERIE

                          John E.  Zapotosky
                 Center for Lake  Erie Area Research
                      The  Ohio State University
INTRODUCTION

      Transparency and conductivity surveys  were conducted in the cen-
tral and western basins of Lake Erie for 1973 through 1975.  A 30-cm
black and white Secchi disk was used to determine  transparency by
lowering it  on a marked line  into the water until  it disappeared from
sight.  This depth is termed  the  Secchi depth.   Specific  conductance
and temperature were measured with a  Martek Mark II Model A in situ
monitoring  system and  recorded in  micromhos per  centimeter (xjmhos/
cm) and °C.   Prior to each cruise the  conductivity meter was calibrated
against a standard and  batteries were changed.

SECCHI DISK TRANSPARENCY

      Values for the area-weighted basin average  for the  Secchi  depth
transparency  are  presented for the  years 1973 through 1975 (Figure  45).
Except for  1973,  these data were recorded during the  period April to
December in  both  the  central  and western portions  of Lake Erie.  Al-
though  1973 values are presented, they  are not included  in the following
discussion due to the shortness of the observation period  (July-Novem-
ber).   The  area-weighted averages  are  presented as Secchi depth  re-
ciprocals as an indicator of particulate  matter (Vollenweider, 1960;
Postma,  1961) to effect a  comparison with similar  data collected earlier
(1969-1971) by the Canada Centre for Inland  Waters (Dobson et  al.  1974).

      Secchi values (this study and  Dobson et al. 1974) demonstrate  a
gradual increase  in depth (decrease  in surface particulates) from April
                                  103

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-------
through July, followed by decreasing values into  December (Figure 45)
in both the  central and western basins of Lake Erie.   Pinsak (1967),
using an in situ turbimeter,  reported a 50 percent increase in suspended
material TiT the central basin (July-November).   He attributed the in-
crease  to a  seasonal  increase  in organic  material, movement of water
from the western basin,  turbulent storm effects  and  vertical circulation
of the entire water  column at turnover.   The latter two effects are well
demonstrated in Figure 45.  A sampling of the central basin before and
after a strong  northeast  storm showed a reduction of the  Secchi depth
by 1-3  m.   Influences of the western basin are readily apparent by
distribution patterns which place shallow Secchi  depths at the west and
southwest portion of the  central basin.   Secchi depths,  when taken as
a yearly average, are approximately 3  m deeper in the central basin
than in the  western basin.

      The average yearly value for  both the central (4.4 m) and western
(1.3 m) basins was 0.4  m greater  in 1974 than  in 1975 (even though  a
peak value of 8 m was recorded in July 1975).  Precipitation in the
Great Lakes basin was significantly greater in 1975 than  in 1974  (Figure
46);  likewise,  rainfall in the Lake Erie basin was 4.8 inches greater in
1975 than in 1974 and 5.11  inches greater than the previous 75-year
average annual rainfall (Figure 47).  The month  of August was  4.32
inches  greater than the 75-year average monthly  rainfall  for August.

Central Basin
      Cruise peak values  (July) of 6.7 m,  6.3 m and 8.0 m (3-year
mean value, 7 m) obtained  from  1973-1975 respectively, show a deeper
Secchi  depth (less particulates) than a July peak  value of 5 m for 1969-
1971  (Dobson et  al.  1974).   When plotted,  cruise contours show a yearly
range of  values  of 1 to 13  m in the central basin.   Generally,  shallower
values  are  found in the southwest portions of the basin and along the
south shore.   Larger  Secchi depths were  obtained in mid-lake  areas
often with one or two  lenses of high surface transparency  in the eastern
and  western portions of the central basin.

Western Basin
      The  western basin also experiences peak values during July; how-
ever,  fluctuations appear more marked (due  in part to the reciprocal
nature  of graph) and are of  greater  frequency.   This basin is  subject to
higher  direct inputs of particulates from tributaries,  and due to its
shallow nature (mean depth, 8.5 m), is subject  to frequent resuspensions.
As presented elsewhere,  1975 was characterized meteorologically as
                                   105

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                                   I I I I
I i i i  i I i I i i i "I i I I I I  [ I I I I  I [ l I I I I  I I I I I I [  I I I i i

                       GREAT LAKES BASIN
                    Average Monthly  Precipitation

                             LEGEND

-------
QJ
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    7 -
    6 -
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           TOTAL RAINFALL
            1973  37.01
            1974  34.1 5
            1975  38.95
       AVG. YEARLY RAINFALL
        1900-1974 33.84
        1965-1974  35.82
     LAKE ERIE BASIN
Average Monthly Precipitation

         LEGEND
              1900-1974
              1973
  	  1974
              1975
    Q I I I I I I  I I I t I ll I  I I I I I I I  I I I I I I I I  I I I I I  I I I I I I I  I I I I I I I  I I I I I  I I I I I I I  I I I I I I I  I 1 I I I
       10 20    10 20   10 20   10 20   10 20   10 20   10 20   10 20    10 20   10 20    10 20    10 20
        JAN    FEB   MAR    APR    MAY     JUN    JUL    AUG    SEP    OCT    NOV    DEC

                                           MONTH
            Figure 47.   Lake Erie basin average monthly precipitation.

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 having lower wind  velocities,  a marked change in dominant  wind direc-
 tion,  and high  surface water temperatures  relative to 1973 or  1974.
 All of these  phenomenon impinge on column mixing; thus, 1974 values
 have probably been subject to a combination of Detroit River discharge
 modified by a greater  resuspension of  bottom  materials (Figure 48).
SPECIFIC CONDUCTANCE (TOTAL DISSOLVED SOLIDS)

    The specific conductance of the western and central basins of Lake
Erie was normalized to 25°C,  then volume-weighted  for 10  cruises  in
1974 (April-October) and 6 cruises  in 1975 (March-December) (Table 21).
Surface  and  bottom contour maps for 1973-1975  were constructed to show
distributional patterns.

   TABLE 21.  SPECIFIC CONDUCTANCE IN  THE CENTRAL  AND
   WESTERN BASINS  OF  LAKE ERIE, 1974 - 1975, (UMHOS/CM)'
~~~~~~~---~__Year
Basin ~ -—— . ^_
Central Basin
Western Basin
Difference
1974
291.32 t 9.72
259.89 t 8.10
31.43
1975
266.0 ± 16.94
227.23 t 24.05
38 . 77
Difference
25.32
32.66

     The trend in 1975 showed a gradual decrease in  values  from April
 to  late August after which values increased  sharply until the last cruise.
 in  December (Figure 48).   The  International  Joint Commission (IJC,
 1975)  has  identified  the Detroit River as a source of low conductance
 water that  exerts a  "flushing principle" on the  western basin.  They
 suggest an apparent decrease in yearly average conductivity from  1966-
 1973 as possibly due to  an increase in yearly flow (132O m^/sec) of
 the Detroit River during this period.  Indeed, the 1974  western basin
 conductance values showed a good inverse relationship (Figure  49) im-
 plying a modifying parameter .in addition to the  Detroit River discharge.


      Conductivity values for the central basin in 1975 followed a trend
 similar to  that demonstrated for the western basin, but  had  a less
 marked decreasing and increasing  slope (Figure 49).   Values in the
 central basin in 1974 showed a decrease only from June through late
                                   103

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                      O 240
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                     U.
"{.  230
                        220
                        310
                        300
                        290
                        280
                        270
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5
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                        240
                        230
                        220
                              1975-
                                                    DISCHARGE DETROIT RIVER (MONTHLY AVERAGE)
                                                    CONDUCTANCt (CRUISE AVERAGE1)
                         CENTRAL BASIN WATER COLUMN


                                                HYPOLIMNION ^__.
                                                                  WESTERN BASIN WATER COLUMN
210
200

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M

A

M

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                                                                MONTHS
                                   Figure 48.   Specific  conductance  in  Lake  Erie  1974,

-------
 O
 UJ
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    240
    230
    220
1974
1

    31O
   300
   29O
   280
   270
   26O
   250
   240
                     DISCHARGE DETROIT RIVER (MONTHLY AVERAGE)
CONDUCTANCE (CRUISE AVERAGE)
                      ,^-«

                  ,-IHYPOLIMNION
                                                   CENTRAL BASIN WATER COLUMN
                                          EPILIMNION
                            WESTERN BASIN WATER  COLUMN

A

M

J

J

A

S

O


                               MONTHS
          Figure  49.  Specific conductance  in  Lake Erie  1975.

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July, while values in the western basin for the same year showed a
decrease from April-September.   Generally,  the  only  apparently  con-
sistent  pattern in the central  basin for both years was that basin  values
decrease in late spring and increase from early fall through December.
The entire water column average closely  followed the epilimnion con-
centrations,  while average hypolimnetic values increased almost linearly
during the stratified portion of the season (+  0.16 and + 0.13>jmhos/
day"1 in 1974  and 1975, respectively).  The greatest influence  of epi-
limnion  concentration was apparently due  to the high epilimnetic volume
(65-75 percent of entire column) relative  to the hypolimnetic volume.
Higher  conductivities are recorded in the central  basin than  in  the
western basin,  an average of 31 and 39 jumhos greater in  1974  and 1975,
respectively.

      In both  1974 and 1975,  average  values of 291  and 266 >umhos for
the central  basin and 260 and 227  jumhos  for  the  western basin  were
recorded.  These yearly values  for the basin  were within  the IJC recom-
mended  level of less than 308 >umhos  (Figure 50).  However, the  U.S.
Army,  Corps of Engineers (1975)  reported that 67.5 percent of the
total  1975 phosphorus loading into  Lake Erie  occurred from  January
through  March.  Assuming the bulk of conductive materials entering
the lake are loaded  at the same time, then the values reported here
are on  the low side when compared with  earlier data which may have
been biased by nearshore measurements.

TEMPERATURE

      Seasonal changes in air temperatures (Figures 51  and  52) and
water temperatures  were similar for  the  first two years of the study.
Dramatic changes  in the  meteorological conditions in 1975 are discussed
in the Overview, Dissolved Oxygen and Winds sections of this  report.
The following discussion of water  temperature in 1974 represents typical
seasonal trends  which occur  in Lake  Erie.

Surface  1974

      Surface temperatures in early April showed a spring warming
trend in the western basin and along the Ohio  shore,  particularly
influenced by the Maumee River.   The Ontario shore and the northeast-
ern part of the central  basin  were the coolest areas (2°C), a situation
which persisted for several months.   By  early May the western basin
had warmed to 10°C and the cool part of  the  central basin was  up to
6°C.  The temperature differential was still evident  in early June with
a greater than 6°C  rise from the northeastern to the southwestern poi—
tion of the central basin.  By mid-August the  two basins were very
                                  111

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                                              •OBJECTIVE LEVEL FOR
                                                TDS IF PROPOSED CON-
                                                VERSION FACTOR OF
                                                O.65 IS USED TO INDI-
                                                CATE SPECIFIC CON-
                                                DUCTIVITY
200
      1966 1967  1968 1969 1970 1971 1972  1973 1974  1975 1976 1977

                            YEAR
      Figure 50.   Specific conductance in Lake Erie.
                                112

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                                                       Water Temperature(°F)
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                    JAN    FEB   MAR   APR   MAY
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                                         JUN    JUL    AUG
10 20    10 20   10 20  10 20
SEP    OCT    NOV   DEC
                                                     YE4R-I973
                    Figure 51 .   Air and water  temperatures  at  Put-in-Bay, Ohio 1973.

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                           TEMPERATURE (°F)
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similar in surface temperature with only a 2° range.  In early Septem-
ber the cooling  of the upper Great Lakes became evident as the Detroit
River flow lowered the temperature of the western  basin by 4°C.  The
lake overturned in Mid-September  and by late October the surface tem-
peratures were  only  half of what they were  in early September.

Bottom  1974
      In early April much of the bottom water in the western and cen-
tral  basins  was 4°C at its most dense  point.  Maumee River flow ap-
peared to be warming the southwestern segment of the western basin.
By early May warming was very evident  along the  Ohio shoreline but
was  less well developed near the Ontario shore.   The  bottom tempera-
ture of the  western basin  doubled while the  central basin showed a  much
smaller rise, reflecting the  stratification that had taken place in that
basin.  This is also apparent from the surface temperature map for
early June.  In mid-August the bottom water reached its greatest degree
of warmth and by early September the western basin  and the nearshore
(unstratified) areas  of the central basin had cooled considerably. The
deeper  portion remained  between 12°-14°C  until turnover in mid-Sep-
tember.  In late October  the two basins were nearly isothermal and
ranged  between 10°C-12°C.

CONCLUSIONS

      From the survey of these three parameters,  the following can be
concluded:

      1.  Secchi values for both the  central and  western basins
          showed a  gradual increase  in depth from April through
          July and August and  a general decrease in depths there-
          after.  This phenomenon is more  apparent in the  central
          basin which, over  the shipping  season, showed deeper
          measures than  the more variable  western basin.

      2.  In the central basin cruise  peak values for 1973-1975
          were greater than the average peak values  for 1969-
          1971.

      3.  Cruise peak values for the  western basin for 1974-1975
          were similar to the peak average  values  obtained by
          Dobson et al. (1974) for the period 1969-1971.
                                  115

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      4.   For  the period April-December 1974, average  con-
          ductance values in the  western and central basins
          fell below the IJC  criterion of 308 umhos.

      5.   The  western basin conductance values apparently
          vary inversely to  the Detroit River discharge,  a
          relationship probably modified by  wind-induced
          mixing.

      6.   Central basin conductance values are usually higher
          than  western basin values and follow  a general pat-
          tern  of values decreasing  in late spring and increas-
          ing from September through December.  Hypolimnetic
          values  increase  linearly, while epilimnion values are
          more subject to fluctuations„

      7.   The central  basin  of  Lake Erie  is isothermal through-
          out winter and early  spring  with stratification occurring
          in late  May  or June.

      8.   Central basin stratification persists for approximately
          100 days with overturn  generally occurring in Sep-
          tember.

     9.   Because of its shallow  depth,  the  western basin rarely
          stratifies and when it does it is for only  short  periods
          of time.

REFERENCES

Chandler,  David  C.   194O.   Limnological studies of western Lake
      Erie, I,  plankton and  certain  phy si cal-chemical data of the
      Bass Island region from  September 1938 to November  1939.
      Ohio J.  Sci.  40(6):291-336.

Dobson,  H. F. H., M. Gilbertson and  P. G.  Sly.   1974.  A  summary
      and comparison  of nutrients and related water  quality in  Lakes
      Erie, Ontario,  Huron,  and  Superior.   J. Fish. Res.  Bd. Can.
      31:731-738..
                                 116

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International  Joint Commission.   1975.   Great Lakes Water Quality,
     third annual report [1974] Appendix  B.  ISC Water Quality  Bd.
     212  p.

Pinsak, A.  P.  1967.  Water transparency in Lake Erie.  Proc.  10th
     Conf.  Great Lakes  Res.  p. 309-321.

Postma, H.   1961.   Suspended matter and Secchi  disc visibility in
     coastal waters.  Netherlands J. Sea Res.  1(3):359-390.

U.S. Army, Corps  of Engineers.  1975.   Lake Erie water manage-
     ment study, Vol.  3.  U.S.  Army, Corps of  Eng., Buffalo Dist.
     Buffalo, N.Y.

Vollenweider, R.  A.  1960.  Beitrage zur Kenntnis Optischer eigen-
     schaften der gewasser und prima produktion.   Mem.  1st.  Ital.
     Idrobiol.   12:201-244.
                                  117

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                              SECTION 5

          LAKE ERIE WINDS:  A PRELIMINARY ANALYSIS
                               1973-1975

                            Daniel L.  Wise
                     Department of Geography and
                 Center  for Lake Erie Area Research
                       The Ohio State University
INTRODUCTION

      The ability to estimate  accurately the wind field over Lake Erie  is
necessitated by the. fact  that seiches, currents,  and waves  on the lake
are directly related to ovei—lake wind field.

      The wind blowing  over the lake surface produces a rhythmic  short-
term  oscillation of the lake level called  a seiche.  Seiche  activity on
Lake  Erie has  resulted  in differences in  water level  between Toledo  and
Buffalo of over 3.5 meters (Platzman,  1963).   Abnormal low  water levels
can seriously hinder navigation near the Detroit River or power  produc-
tion on the  Niagara River.   Gillies (1959) notes that  a 0.93 meter drop
in lake elevation at Buffalo can  reduce  potential electrical energy genera-
tion on the  Niagara River by  1200 megawatts.

      The wind-generated currents at the surface can  influence subsurface
motion  and  change the thermal  structure  of Lake Erie which,  in turn,
can affect such properties as the degree  of oxygen depletion.   Currents
effect the dispersion of  water-borne pollutants and  the formation,  move-
ment,  and dispersion of ice.   They  are  also related  to  the distribution
of such water  properties as alkalinity and turbidity.   Gedney and  Lick
(1970) have developed a  numerical model  based on  finite differences
which calculates the  steady state,  wind driven currents  in Lake Erie as
a function of depth and  horizontal  position.

      Wave  characteristics, principally wave height and  wave period, are
sought for both the average and extreme  situations for the  planning and
construction of adequate  yet economical breakwaters which  reduce pos-
sible  erosion or damage to coastal installations.   Accurate estimates of
mid-lake  wave  characteristics,  associated with a given wind field,  are
necessary for  both commercial  and recreational  boaters.
                                   118

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Previous Studies

     Various  methods  for estimating the winds have been proposed.
Examples of methods applied to  Lake Erie are given by  Hunt (1959),
Lemire  (1961), Richards et  al. (1966),  Barrientos (1971) and Feit
and Barrientos  (1974).

     The  number of over-lake wind observations are too sparse or
infrequent to  be used as the sole determinant of the ovei—lake wind
field.  Various investigators (Hunt, 1959;  Lemire,  1961; and Richards
et al.  1966) have employed the  relationship between simultaneously
observed over-lake and over-land wind  speed observations.   They  esti-
mate the ovei—lake wind speed from the computed  relationship (R) of
the wind speed  over water (U  )  to the wind  speed  over land (Up where:

                              R =

R  deviates  from unity in  response to the various influences  which  cause
the wind speed  over water to vary from that over  the  land;  i.e.:

      1 .   The difference in frictional effect between land and water,

      2.   The difference in atmospheric stability induced by ati—water
          temperature differences,

      3.   The length of the over water  fetch.

Examples of  R  obtained  in  Lake Erie studies are:

                                 R(Annual)    R(Sprt ng)  R(Fall)
      Hunt  (1959)                  1.56        1.35      1.82
       Lemire (1961)               1.63        1.38      1.87
      Richards  et  al. (1966)       1.66        1.33      1.85

      Hunt (1959) and Richards et al.(1966) studied  the effects of stabil-
ity on R while  the latter also  included  the  influence of fetch  on R.
These studies found that:

       1.  R increases as over-water stability increases.

      2.  Under stable ovei—water conditions, R increases as the
          over-lake fetch increases up  to 20  km.
                                   119

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      In the aforementioned studies,  R was  determined by  dividing the
 lake  into arbitrary sections such  that each  section had one land station
 with  which to correlate ship  observations.  This  method lacks  rigor
 since ship  observations occur at different locations within  these sections;
 thus,  the resulting R  is,  at  best,  representative  of the entire section,
 and does not supply information of sufficient density to be useful in
 assessing spatial variation.  A  more rigorous approach  would be to
 expand, by  interpolation,  the observed wind speed values from  the  land
 stations to over-lake  locations.   It could then  be  assumed that  the
 interpolated values and  corresponding ship observations are for the  same
 location on the lake and a single  relationship  between the observed winds
 could be determined.   This was  the  method suggested by Barrientos
 (1971),  but  instead of using an  objective  interpolation  algorithm he
 devised subjective equations to reduce land  station observations to
 inferred values representing  half the  lake,  e.g.:

      East Erie =- 0.25 (Cleveland) + 0.50 (Erie) +0.15  (Buffalo)

      He used this method because the accuracy of the interpolation
 procedure was not compatable with the other assumptions made.  Inter-
 polation could not realistically  be used since station input  from Canada
 was lacking, thus only extrapolation  could result.   In a  later study
 (Feit and Barrientos,  1974) which did use Canadian data, interpolation
 was used to reduce  the  land  station observations to over-lake locations.
 For both studies,  regression equations were developed to predict the
 surface winds from  forecasted  meteorological  elements,  not just wind
 speeds.  The  entire methodology is an improvement over  previous
 studies, but still does not provide sufficient information  concerning  the
 spatial variation of the winds.
Study  Purpose  and Scope

     The purpose  of this study  is to provide useful information concern-
ing the winds over  Lake Erie.   To provide this information two different
objectives were  necessary.

     All of the aforementioned studies  estimate a wind speed,  repre-
sentative  of large  sections  of the lake, based on empirical relationships
between simultaneously observed over-lake and over-land  meteorological
elements.   None of these methods provide a  rigorous investigation of
the spatial  variation of the  surface winds, i .e., the  surface  wind field.
Therefore,  a primary objective  is the development of a  methodology,
using theoretical considerations  as  well  as empirical relationships,
                                   120

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to estimate the surface wind  field of Lake  Erie.   Meteorological ele-
ments,  primarily those recorded at surrounding land stations,  but  also
those from a limited number of concurrent over-lake measurements,
are  interpolated to  a 15-kilometer grid network over Lake Erie.   Pre-
dictive  equations, which reflect  empirical  and/or theoretical  considera-
tions,  and which employ the  interpolated values of the  meteorological
elements,  are applied at  each grid node of the grid network  to  produce
the estimated surface  wind field.

     The wind  field methodology will not be fully operational  until June,
1977, yet  ongoing investigation of lake  eutrophication requires  informa-
tion concerning the  winds  at  present.   Thus a  second objective  was set.
A quick and simple  means of assessing the  winds had to be  developed
for use until the primary  method was operational.   The remainder of
this report details the selection, techniques, results and conclusions qf
this secondary  wind analysis.

     While one of the methods previously  discussed could have  been
employed, it was decided  to  use wind data from  Long  Point, Ontario
as  an estimate of over-lake winds.   Of the  various land stations sur-
rounding  Lake Erie,  Long  Point offers the best approximation  to the
over-lake  winds of  the central basin (Burns and Ross,  1972).   No  pre-
tense is made that  Long  Point is truly representative of the  ovei—lake
conditions.  Its  location,   however, does offer minimal influence from
surrounding  land, the  hourly data were readily available,  and the  data
are sufficiently representative for the preliminary  assessment  required
until the  wind field methodology is available.


ANALYSIS

Data

      This particular  study uses hourly wind data obtained for the  years
 1973 through 1975.   Since the lighthouse  at Long Point operates only
during  the shipping  season, wind data were only available for April
through December.   Wind data  from other meteorological stations  in
close  proximity to  Lake  Erie were also secured for use  in  later studies
employing the  wind field  model.  Meteorological observations taken
aboard the R/V Hydra will be used in both the formulation and testing
of the  wind field model.
                                   121

-------
 Technique

      Two basic transformations of the raw data were performed.  First,
 a "wind summary" was  prepared.  This  wind summary was simply the
 listing,  by month,  of the hourly  wind speeds and directions for all  the
 data.   Secondly, a "wind  analysis" for various periods of time was
 conducted.  This analysis yielded:

      1 .   The resultant  wind speed,
      2.   The direction  of the resultant wind,
      3.   The persistance of the  wind, and
      4.   The mean speed of the wind.

 for the various  periods  selected.   The resultant wind is the vectoral
 average of all wind directions and  speeds during  the selected  periods.
 The individual observations are resolved  into north  and east components,
 and then  averaged for the  given period.  The averaged  components  are
 then reconverted  into a  single vector.   For a site with eight  compass
 point directions,  such as Long  Point, the computation  is rather simple
 (Panofsky and Brier  1965).   If  Rx  is the component of the resultant
 wind  in the east  direction  and Ry the component in  the  north direction,
 then:
      Rx  = IW-IE -f .707(ISW + INW) - .707CJSE  + INE)
                                    N
      Ry =  IS-IN +  .707(ISW + ISE)  -  .707(TNE  4 INW)
                                    N

In the numerator,  W  is the speed  of each  individual west wind,  SE the
magnitude of  each  south-east  wind, and so forth.  The  denominator,  N,
is the number of observations during the time interval .

      Ur = V^RX)2 +  (Ry)2

while the direction of the  resultant wind (DIR  )  is
                                              r
      DIRr =  TAN  (RX/R  )

The  mean wind speed (Um), regardless of direction,  is

      Um =  I N+ INE4IE4 ISE+IS+ISW-fl W+INW
                             N

The  speed of the resultant wind  is smaller than the mean wind speed of
the individual winds.  A striking example of this would occur  if the
                                  122

-------
wind  is equally likely to blow  from all  directions.   In this case, the
resultant  wind would be zero.

      The persistence (P) of the wind  is defined by
Thus,  if the wind  blows from  the same  direction for the entire  period,
the persistence would equal  1.0,  while in  the case above of the equally
distributed wind,  the  persistence  would be 0.0.   Persistence is an indi-
cator of the  regularity  of the wind.   The parameters Ur,  DIRp,  and P
are  important  in the study of waves, seiches, or  currents,  while Up-,
would  be  important in determining evaporation, cooling power or any-
variable determined by the  strength  of the wind  and not its direction.

     Wind histograms were  also constructed  for various periods based
on the hourly wind data.  A wind histogram is used to show the distri-
bution of wind speeds and directions experienced at a  given  location
over a specified period of time.  Wind histograms were developed to
illustrate the frequency of occurrence  (by  percent) of six wind speed
classifications (0-10,  11-16,  17-21,  22-27, 28-33, and 34-40 knots) for
the eight  compass directions.   The periods April  through June  and May
through September were chosen because of their possible significance to
the study of eutrophication  in  Lake  Erie.


DISCUSSION
          results of this study are presented in two segments.  The
first segment is a general discussion of the winds observed during the
entire  study period.   The  second segment focuses around the analysis
of the  winds for April through June of each year.  These three months
represent a  period of lake stratification.   It was suggested that varia-
tions  in  the  wind,  which occurred  during  this period  in 1975  (as com-
pared to 1973 or 1974),  may have influenced the formation  of the  thicker
hypolimnion  and high dissolved oxygen concentration.

General

     The results of the wind analysis technique, when  applied  to  monthly
and yearly data, are presented in  Table 22.  General characteristics
observed during all three years  include:
                                   123

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                  TABLE 22.   RESULTS OF THE WIND ANALYSIS FOR VARIOUS
                          PERIODS AT LONG POINT, ONTARIO:   1973-1975
Period
of
Summation
April
May
June
July
August
September
October
November
December
April
through
June
April
through
December
1973
Resultant wind
Velocity
&)
1.77
4.71
8.04
4.14
4.55
1.89
1.62
10.42
3.64

4.27

4.19
Direction
, 01Rr i
(degrSe.)
313
219
210
227
235
274
244
255
232

221

235
Persistence
<«"'
9.5
28.6
56.7
31.1
37.7
12.7
10.3
49.1
18.7

26.1

26.6

Velocity
U
" <-ph)
18.68
16.46
14.18
13.32
12.08
14.83
15.69
21.21
19.47

16.39

15.77
1974
Resultant wind
Velocity
&h)
9.66
4.87
6.14
6.O6
4.32
5.31
7. 02
7.O4
5.45

6.72

5.76
Direction
, OIRr
(degree*)
219
229
196
233
210
243
261
262
261

215

235
Persistence
WP>
49.9
30.0
42.5
47.6
35.3
33.0
41.2
36.2
25.7

4O.3

35.3
Velocity
"(•ph)
19.34
16.23
14.45
12.71
12.29
16.09
17.06
19.43
21.20

16.66

16.31
1975
Resultant wind
"Velocity
(•&)
6.05
3.82
3.79
7.11
2.59
4.31
4.92
11.68
4.82

3.33

4.96
Direction
DIP.
(degrele)
308
231
215
236
22O
258
252
239
242

259

246
Persistence
<•)"'
34.9
29.7
27.4
58.7
19.3
27.6
27.3
59.8
22.6

22.7

31.5
Mean
Velocity
U.
l-ph)
17.37
12.85
13.84
12.12
13.42
15.61
18.06
19.54
21.36

14.66

15.73
ro

-------
      1.   The  annual resultant wind is  from the west-southwest at
          approximately 5.0 mph.

      2.   During the year,  the  resultant wind  velocity (Ur)  is greatest
          in the late fall with a secondary maximum in  the  spring.
          The  minimum resultant wind  velocity consistently  occurs in
          late  summer.  This same trend is also apparent  in the mean
          wind  velocity (Um).

The  first characteristic reflects the location of lake within  the westerly
wind  belt of the general circulation. The dominance of southwest  winds
is further emphasized in Table 23, which  lists the percent  frequency of
wind  direction for the eight compass  directions  for each year.    The
second characteristic is graphically presented in Figure  53.  The ori-
ginal monthly resultant wind  velocities  were smoothed by means of a
three month overlapping average to facilitate analysis.   The observed
trend can be explained  by two plausible factors,  (1) seasonal  changes
within the general circulation and  (2) stability.  During  the  summer  the
mean hemispheric pressure gradient is reduced,  and the westerly wind
belt  is diplaced northward.  As a  consequence of these seasonal changes,
Lake Erie experiences  weaker, less persistent winds.   The lake  is
cooler in the summer than the  air above it.   This condition inhibits
mixing and thus reduces the  surface winds.   Both  proposed factors
should be fully investigated.
April through June

     The thermal stratification of the lake,  which  is affected by currents,
seiche activity and  waves  is  dependent to some  extent on the  surface
wind speed, the duration of the wind from  a given direction (persis-
tence),  fetch  (determined by wind direction) and atmospheric stability.

     Atmospheric stability  is evaluated  by computing the air-water  tem-
perature difference (AT) between  the  average daily water temperature at
Marblehead, Ohio and the  average daily temperature at  Sandusky,  Ohio.
These  results  are  not representative  of the  stability  conditions for the
entire  lake,  instead the  results are  meant merely  to serve as a first
approximation  to assessing stability.   The average values  of AT  for this
period were 2.2°C,  2.1°C, and 1 .6°C  for 1973,  1974 and 1975 respec-
tively.   While AT  is  positive,  indicating a stable layer of  air, AT is not
large enough to influence the winds significantly (Jacobs,  1965; Strong
and Bellaire,  1965).
                                   125

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TABLE  23.  PERCENT  FREQUENCY OF THE 8-POINT WIND
  DIRECTIONS DERIVED FROM HOURLY WIND  DATA FOR
  LONG POINT, ONTARIO,  APRIL-DECEMBER,  1973-1975
Year
1973
1974
1975
Direction and Percent Frequency
N
6.6
8.7
7.7
NE
15.1
11 .9
9.9
E
7.3
5.8
7.3
SE
4.9
5.4
5.5
S
12.9
12.0
12.0
SW
31 .4
35.3
28.5
W
11 .3
11 .3
16.1
NW
10.7
9.4
12.9

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         8.0'
         7.0- -
         6.0--

      ?
      Q.
      E,

      2?  5.0--
      S
      C  4.0--
      S
      3
      0)
      o:
         3.0--
        2.0"
                                1973

                                1974

                                1975
                  M     J
                                     A
                                   Months
        Figure 53.   Monthly  resultant wind velocities for
                      Long Point, Ontario.
z
111
  40
   30
   20
   10
                 I
       N NE E SE S SW W NW


           1973
          I
                                 IT
N NE E SE S SW W NW


       1974
  LEGEND


 • > 20.1 mph

 ^ 10.1 -20.0 mph

 	 0.0-10.0 mph
N NE E SE S SW W NW


       1975
     Figure 54.   Histogram  of resultant  winds  at Long Point,
                   Ontario,  April-June  1973-1975.
                                 127

-------
      Inspection of the wind analysis results (Table 22) during this  per-
iod of time reveal slight  but  important differences between 1975 and
1973  or  1974.  In 1975, both the resultant  wind velocity and  the mean
wind  velocity were lower  than the  previous  two years.  Also, in  1973
and 1974 the  resultant wind directions were 221O and 215° respectively,
while in 1975 the resultant  wind direction was 259°.  A wind histogram,
computed from the daily resultant  winds of  this  period, is presented  in
Figure 54,  and helps to explain  these  differences.  The dominance  of
the southwest winds  is obvious  in  1973 and  1974.  During  1975, however,
although prevailing southwest  winds continued to be present,  a much
more uniform distribution occurred.   In fact,  southwest winds, which
produce  the greatest over-lake fetch for this location, occurred almost
twice as often in  1973 (39.9 percent) and 1974 (41.7  percent) as com-
pared to 1975 (22.2  percent).  Also,  the winds, regardless of direction,
had lower  magnitudes in 1975 than either 1973 or  1974.   Only 53 per-
cent of the  winds during this  period in 1975 were  greater  than  10 miles
per hour,  while for  the same period in both 1973  and 1974,  70 percent
of the winds were in excess of 10  miles per hour.  The winds from
April  through June 1975 were weaker and more  evenly distributed than
for the same  period  during  either  1973 or  1974  (Figure 54).

CONCLUSIONS

      The following conclusions  can be made from  this study:

      1 .   Although the predominant winds at Long  Point, Ontario
          are from the southwest (average  speed 11-16  knots), the
          distribution of the winds  often  show marked variation
          from month to month  or  even year to year.

      2.   The distribution of the winds for April through June 1975
          was significantly different from the distributions  of  the
          same period in  1973 and  1974.  Such differences in the
          wind are an important  element in  the assessment of phys-
          ical, chemical,  or biological processes occurring in the
          lake.

      3.   The Long  Point,  Ontario  wind data offers an unrefined
          estimate of the central basin winds which is sufficient
          for  examining the gross  relationships between wind
          and  other parameters.   For  more detailed studies
          involving spatial variation, the wind field method will
          be necessary.

     4.  There is a need for more reliable and more frequent
         over—lake  measurements,  possibly from permanent

                                   128

-------
          buoys.   Also,  other  meteorological elements such
          as rainfall, solar radiation,  evaporation, etc.
          should be monitored  at both coastal  and over-lake
          sites and analyzed for possible influences on lake
          eutrophication.
REFERENCES

Barrientos, C.S.   1971.  An  objective method  for forecasting  winds
     over Lake Erie and  Lake Ontario.  Proc.  14th Conf.  Great
     Lakes Res.,  Internat.  Assoc.  Great Lakes Res.,  p.  4O1-411.

Burns,  N. and C.  Ross (eds).   1972.   Project Hypo.   CCIW Paper No.
     6.   USEPA Tech. Rept. TS-05-71 -208-24.   182  p.

Felt,  D.M. and C.S.  Barrientos.  1974.  Great Lakes wind forecasts
     based on model output statistics.   Proc. 17th Conf. Great  Lakes
     Res., Internat. Assoc. Great Lakes Res.  p. 725-732.

Gedney,  R. and W. Lick.   1970.   Numerical calculations of the  steady-
     state, wind driven currents in Lake  Erie.   Proc. 13th Conf.
     Great Lakes Res.,  Internat. Assoc.  Great Lakes  Res.  p.  829-
     838.

Gillies,  O.K.A.  1959.   Winds and water levels on Lake Erie.  Royal
     Meteorological Society, Canadian Branch,,  Vol. 9. No. 1.  p.
     12-24.

Hunt, I.A.   1959.   Winds, wind  set-ups and  seiches on Lake Erie,
     part  2.   U.S. Corps of  Eng. Lake  Survey  58 p.

Jacobs,  S.J.  1965.  Wave hindcasts  vs.  recorded waves.   Final
     Rept. O6768-1-f,  Office of Res.  Admin.  Univ. Mich.

Lemire, F.   1961.  Winds on the Great  Lakes.   Univ. of Toronto,
     Great Lakes Inst.   Prelim. Rept.  Ser. No. 2.   9 p.

Panofsky,  H.A. and G.W.  Brier.  1965.  Some applications of statis-
     tics to meteorology.   Penn. State Univ.  University  Park,  Penn-
     sylvania.  224 p.

Platzman, G.W.  1963.  The  dynamic  prediction of wind tides on  Lake
     Erie.  Meteor. Monogr.   No. 4.  44 p.
                                 129

-------
Richards, T.,  H. Dragert and  D.R. Mclntyre.   1966.   Influence of
     atmospheric stability and  ovei—water fetch on winds  over the
     lower  Great Lakes.  Month.  Weather Rev. Vol. 94.  p. 448-
     453.

Strong, A.E. and F.R. Bellaire.   1965.   The effect of air stability  on
     wind and  waves.  Great Lakes Res. Div.,  Univ.  Mich.  Pub.  No.
     13.  p. 283-289.
                                  130

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                             SECTION  6

     pHOSpHORUS BUDGET OF THE CENTRAL AND  WESTERN
                 BASINS OF LAKE ERIE:   1973-1975

                            Karlis Svanks
                 Department of Chemical Engineering
                      The Ohio State University

                           David E.  Rathke
                 Center for Lake  Erie Area Research
                      The Ohio State University
INTRODUCTION

      Nutrient budget studies provide a basis for the quantitative assess-
ment  of the net transfer of materials between conceptualized compart-
ments of  a lake.   Budgets greatly aid  in the investigation of prevailing
transport mechanisms  and the  fate of transported materials.  This  part
of the report  will present the phosphorus budget as determined  by field
measurements and estimated loadings for the  1973, 1974 and  1975 field
seasons (April through December).   The number and locations of the
western and central basin sampling stations, procedures for sample
preparation, and methods of analysis have been detailed in  the  Overview
section.

PROCEDURES

      A scheme devised by Noel Burns (CCIW) dividing Lake Erie into
grids of estimated area (Overview, Figure 3) was used in estimating
the quantities of phosphorus (P) measured  in the western and central
basins.   The  western basin was divided  into seven grid areas (grids 44
through 5O) and the central basin into 25 grid areas (19 through 43).
The epilimnion,  mesolimnion and hypolimnion volumes for each grid
and survey were calculated by the procedure outlined in the Overview
section.

      The concentrations  measured at stations within each grid  were
used  to calculate the quantity of P for that grid.    During  unstratified

                                   131

-------
 periods the  quantity of P  in each  grid  was obtained by multiplying the
 average concentration measured within tine grid by the total grid vol-
 ume.   Concentrations of P were found to be nearly uniform through-
 out the water column  during unstratified periods,  thus the average
 of the concentration measurements yielded a reliable  estimate.   Dur-
 ing stratified periods  the  quantity of P  was calculated for each  of the
 three  limnions by multiplying the  limnion volume by its average  con-
 centration.  The quantity  of epilimnion  P for each qrid was estimated
 from the average  concentration taken at one  meter below the  surface.
 The measurements taken one meter above  the  mesolimnion were not
 included in determining  the epilimnion  quantity of P,  since a  high
 concentration gradient may exist through the mesolimnion and could
 lead to overestimation of  epilimnion P  if  the two  values were aver-
 aged.   The  quantity of P  in the mesolimnion was  estimated by  using
 the average  of the  concentrations  measured one meter above and one
 meter below the mesolimnion.   The hypolimnion quantities of P for
 each grid  were estimated  by averaging the concentrations measured
 one meter below the  mesolimnion and one  meter above the bottom.
 During anoxic conditions,  when a  sharp increase in the P concentration
 gradient existed  below the bottom  sampling horizon the quantity of P  in
 the hypolimnion  was considered  to be underestimated.  The accuracy of
 all  P quantity estimates largely depends on the accuracy  of the volume
 estimates  of the three limnions.

    The total quantities  for the  entire  central basin and  western basin
 were  calculated  by summing the estimated  total quantity  of P  for  each
 grid within the basin.   For budget calculations during stratified periods,
 the epilimnion was  considered  to consist of both the epilimnion  and
 mesolimnion.  Due to intermixing between  the  two  limnions and  volume
 fluctuations occuring  in the mesolimnion the  two limnions were  com-
 bined,  as was done by Burns (1976). The total central basin or wes-
tern basin epilimnion quantity  of  P was then  determined  by summing
the combined values for all grids  within the  basin.  Similarly the
total basin hypolimnion quantity was determined by summing the hypo-
 limnion P  quantity  of all  grids within the basin.

    The volume-weighted concentrations for the western  and central
basins were  calculated by summing the  estimated total quantities of P
 for each grid and  dividing by the total  basin  volume.   The volume-
weighted concentrations for each  limnion were  similarly  calculated,
using  the volume and quantities appropriate for the  respective limnion.

    Table  24 shows the  calculated volume-weighted  concentrations and
quantities of total phosphorus (TP) used for the 1973 through  1975
central basin P budget calculations.  Similar calculations were  made
for the western basin total phosphorus  budget.

                                  132

-------
                           TABLE  24.
CONCENTRATION  AND  QUANTITIES  OF  PHOSPHORUS
FORMS  IN  LAKE  ERIE  CENTRAL  BASIN
CO
GO



Year
1973






1974













1078

















Cruise
No.
2


6


7
2
4


6


7


e


10
1
2


3


4
(

5
6
1-»6

1-Ki



Conditions
Stratified


Stratified


Unstratlfled
Unstratlfed
Stratified


Stratified


Stratified


Stratified


Unstratifled
Unstratlfled
Stratified


Stratified


Stratified


Unstratifled
Unstratlfled



-Llmnlon
Epl
Me so
Hypo
Epl
Me so
Hypo
-
_
Epl
Me so
Hypo
Epl
Meso
Hypo
Epl
Meso
Hypo
Epl
Meso
Hypo
-
_
Epi
Meso
Hypo
Epl
Meso
Hypo
Epl
Meso
Hypo
-
-
Average volume
time weighted



Volume
Km3
228.63.
22 . 22'
61.31
238. 20 |
24.86'
47.07
3O6.O9
311 .94
195.02
22.74
93.67
249.10
12.52
SO. 12
235.35
23.83
50.63
243.01
17.15
48.33
303.97
3O8.69
174. O3
30.76
104.70
182.64
35.56
90.49
227.39
15.23
66.07
307. 06
303.96
3O7.82

Percent of total phosphorus

Total
Phosphorus
Metric
Tons
3564. O1

940.65
3553. 08

1O04.13
7839. 9O
5247.19
2635.52
431.60
1962.42
3362.87
203.69
961.30
3058 . 23
202 . 38
864.15
4534.88
296.37
IU78.20
6046.21
71OO.86
2421 .42
-•'(59.27
1638.34
^357 0 I
637.71
1919.77
.1488 . 53
215.86
1183. G3
6134.24
9623 . 04
6013.11

cone.
pgm/l_
14.20

15.34
13.51

21.33
25. GO
10.82
13.46
18.06
20.95
13.50
16.29
19.18
12.99
11 .85
17. 07
18.66
16.98
28.49
19. B9
23. OO
13.91
1H.26
15.65
12.91
1 7.94
21 .22
15.34
14.17
17.91
19.98
31.66
19.53

10O.OO%

Reactive
Phosphorus
Metric
Tons











269. O3
27.75
140.24
247.54
41.71
17O.74
395.17
1O9.12
743. OS
629. O2
567.99
457.19
70.94
241. P6
288.87
66.26
2O8.05
632.07
4O. 1O
272 . 98
812.36
2480.56
996.67

10.
one.
ugm/L











1.1O
2. 2O
2.79
1.05
1.75
3.37
1.63
6.25
15.36
2.O7
1.90
2.63
2.31
2.31
1 .58
1 .86
2.31
2.78
2.63
4.13
2.65
8.16
3.24

7%

Partlculate
Phosphorus
Metric
Tons





















5864. r,s
1 590 . 77
333 . 73
1 1 76 . j I
I684.0O
496.77
I52O.79
2370.94
143.78
771 .90
4677. O5
65O4.16
437O.03

cone.
>jgm/L





















19. OO
9.19
10.85
11 .24
9.22
13.97
16.81
1O. 46
9.44
11.68
15.23
21.40
14.20

72.68%

Organic
Phosphorus **
Metric
Tons





















6-18.25
365 . 46
64.60
219.87
383.54
74.68
19O.03
477 . 52
31.98
138.75
644.83
638.32
646.43

cone.
>jgm/L





















(2.55)
(2.16)
(2.K)
(1.79)
(2.89)
(3.83)
(3.40)
(1.46)
(0.79)
(0.00)
(2.56)
C1.27)
2.10

1O.75%
                              Volume weighted
                              The concentration of soluble organic phosphorus was determined by difference (
                              therefor*, least accurate.  For calculation of tons of soluble organic phosphorus
                              2.lO>jgm/l- was assumed coru-tant throughout the season (cruises).
                                                          the values In parenthesis) and  Is,
                                                          In Uils table  the value  of

-------
      In order to obtain a better understanding of the phosphorus budget
 during  1975, total filtered phosphorus (TFP) and particulate  phosphorus
 (PP) were  measured in addition to TP and soluble reactive phosphorus
 (SRP).  Fourteen central  and western  basin  stations were selected  for
 these additional  measurements  of P forms.   The  concentration and
 quantities  of PP  and soluble  organic  phosphorus (SOP) were estimated
 for all  the grids by interpolation and extrapolation from the  measured
 concentrations at the 14 selected stations.   Even  though the  estimates
 made reduced the reliability  of  the PP and SOP  data,  the information
 was valuable in  clarifying some aspects of the transformations of P forms
 in the water.

      The  preliminary estimates  of annual TP loadings (Table 25) and
 monthly and daily average loading of TP and SRP (Table  26) were
 obtained from the Army Corps  of Engineers,  Buffalo District (1977).
 The daily  estimates were  used  to determine  the quantity  of P entering
 the western and  central basins  between  consecutive  cruises.   The phos-
 phorus  loading contributed from precipitation (approximately  900  metric
 tons yearly  for the entire lake)  and the apatite phosphorus contributed
 from shoreline erosion, which  is not considered  to  interact in lake
 water  columns (Burns,  1976), were not accounted for and will not be
 considered  in the  P budget.

      Water flow rates,  P loadings and  concentrations of  P at the inlets
 and outlets of the central  basin  were required to estimate the quantity
 transferred  and  the  quantity retained  for both basins.  Measured flow
 rates for the separate  basins were not available; thus, the flow rates
 (1973-1975)  were estimated using a fraction of the total flow into the
 lake (Table  27).   The estimates were based  on 1970 data  presented by
 Burns (1976).

      The average concentration of P at transects 1  and 6 (Figure 55)
 was  used to estimate the quantity of  P input  into the central basin from
the western  basin and output  from the central basin to the eastern basin.
 It  was assumed  the  western basin flow into the central basin was confined
to the epilimnion and mesolimnion during the stratified period.   Since
at transect 1, stratified conditions  rarely existed, concentrations mea-
sured at all depths were averaged to estimate the quantity of P input
 from  the western basin.  A similar procedure was used to estimate
the quantity  of P leaving the  central basin.   Since transect 6 is  strati-
fied  during the summer months,  the average epilimnion and mesolim-
nion volume-weighted concentrations were used to quantify the amount
of P transported  out of the basin.  During  unstratified periods,  average
values for the entire water column were used for the discharge estimate.
                                   134

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                        TABLE  25.   TOTAL PHOSPHORUS INPUT IN  LAKE ERIE

                                             METRIC TONS1
^"^^ Year
^Sources^^^ Basin
Detroit River
Point
Diffuse
Total
Western* 'basin and
central basin
TOTAL LAKE
1973
Western
11822
1332
4351
17505
Central

2175
1816
3991
21495
23188
1974
Western
11264
1034
4341
16639
Central

1969
2261
423O
20869
22912
1975
Western
10111
1074
3748
14933
Central

1886
1956
3842
18775
20434
CO
01

              Data Source:  U.S. Army Corps of Engineers, Buffalo District.


                   by precipitation and northern shore erosion (apatite phosphorus)  are not considered,

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TABLE 26.   LAKE  ERIE WESTERN  AND CENTRAL  BASIN
AVERAGE  DAILY  TOTAL AND SOLUBLE REACTIVE PHOS-
             PHORUS  LOADS METRIC TONS - 1975
Month
Jan
Feb
Mar
Apr
May
June
July
Aug
Sept
Oct
Nov
Dec
>>v^^ Source
Basin •^
Western
Central
W.B.+C.B.
Western
Central
W.B.4C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Western
Central
W.B.+C.B.
Total Phosphorus
Detroit
River
27.45O
27.450
27.210
27.21O
26.25O
26.25O
27.69O
27.690
27.S9O
27.69O
28.230
28.29O
28.53O
28.530
28.530
28.53O
28.770
28.77O
27.570
27 . 570
27.330
27.33O
27.O9O
27.O9O
Non-
Point
16.187
13.O29
29.216
27.198
19.567
46.765
8.921
11 .444
20.365
7.O46
1 .654
8.7OO
13.320
2.1O6
15.426
12.779
3.953
16.732
3.857
O.161
4.026
3.341
1 .421
4.762
5.559
4.381
9.940
3.547
O.723
4.270
O.927
O.711
1.638
21.7O4
6.193
27.897
(m-tons/dayl
Point
2.957
5.484
8.441
2.957
5.484
8.441
2.957
5.484
8.441
2.957
5.186
8.143
2.957
5.484
8.441
2.957
5.423
8.380
2.902
4.336
7.238
2.906
4.798
7.7O4
2.957
5.4O3
8.360
2.942
4.824
7.766
2.916
4.634
7.55O
2.957
5.484
8.441
Total
46.594
18.513
65.107
57.365
25. 052
82.417
38.128
16.928
55.050
37.693
6.840
44.533
43.967
7.590
51 . 557
44.O26
9.376
53.402
35.2S9
4.496
39.795
34.776
6.219
4O.995
37.286
9.785
47.O71
34.O59
5.547
39.6O6
31 .173
5.345
36.518
51 .751
11.678
63.429
Soluble Re-active Pho=r>horij^ Cm-t™-^/
Detroit
River
12.590
12.590
12.48O
12.480
12.040
12.O4O
12.700
12.7OO
12.700
12.700
12.970
12.970
13.O80
13.O80
13.080
13.080
13.190
13.190
12.64O
12.640
12.530
12.53O
12.420
12.42O
Non-
Point
ft. 755
2.085
5.840
6.5O3
2.668
9.171
2.871
2.095
4.966
2. '.39
0.478
2.917
2.532
O.535
3.O67
2.383
0.5O6
2.869
0.3O3
O.O76
O.379
O.55O
0.357
O.9O7
1.332
O.836
2.168
0.493
0.227
O.720
0.465
O.289
0.754
3.197
1.033
4.23O
Point
1.479
2.551
4.O30
1 .479
2.5'?8
4.007
1 .479
2.65C
4.129
1.479
2.O22
3.5O1
1.479
2.2O3
3.682
1.479
2.407
3.886
1.452
1.752
3.204
1.479
1.935
3.414
1.479
2.4OO
3.879
1.368
1.968
3.336
1.384
1.846
3.230
1.479
2.3O2
3.781
day)
Total
1 7 . 824
4.635
22.459
2O. 462
5.196
25.658
16.390
4.744
21.134
16.618
2.499
19.117
16.711
2.737
19.448
16.832
2.913
19.745
14.834
1.828
19.682
15.1O9
2.292
17.401
16.OO1
3.236
19.237
14.5O1
2.196
16.697
14.378
2.135
16.513
17.O96
3.335
20. 431
Corps of Engineers, Buffalo District Preliminary Estimates.
                                   136

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                        TABLE 27.  FLOW RATES OF WATER  INTO  LAKE  ERIE1
""""\_Year
Month ""*" — .^^
January
February
March
April
May
June
July
August
September
October
November
December
Yearly
Average
Total Flow
per year(Km3)
1973
CFT/SECXIO-J
254
215
360
269
267
290
234
218
191
204
220
257




KMVDAY
0.6214
0.5260
0.8808
0.6581
0.6532
0.7095
0.5725
0.5334
0.4673
0.4991
0.5383
0.6288

0.6082

222.0
1974
CFT/^xia-3
280
252
324
274
294
253
231
206
205
164
294
197




KM-V DAY
0.6850
0.6165
0.7927
0.6704
0.7193
0.6190
0.5652
0 . 5040
0.5O15
0.4012
0.7193
0.4820

0.6060

221 .2
1975
CFT/^xlO-3
271
261
271
255
257
266
210
247
229
194
216
254




KMV DAY
0.6630
0 . 6386
0 . 663O
0 . 6239
0.6288
O.6508
0.5138
0.6043
O . 56O3
0.4746
0.5285
0.6214

0 . 5973

218.0 <
1975^
Into.W.B and
out to C-B.
0.6376
0.6141
0.6376
0.60OO
0 . 6047
0.6259
0.4941
0.5812
0.5388
0 . 4564
0.5083
0.5976

0.5744

209.7
KM^/DAY WT
0 . 6529
0.6288
0.6529
0.6144
0.6192
0.6408
0.5O59
0.5951
0.5517
0.4673
0.5204
0.6119

0 . 5882

214.7
CO
         1
Flow rates  in
                            were estimated by U.S.  Geological  Survey-
        2The flow rates into the western  basin and out to the central basin, and out of central basin
         were estimated from  the total flow rates  into the lake by using factors 0.962 and 0.985
         respectively.
      Note:  The gain of water from precipitation and  losses  due to evaporation are not accounted for.

-------
CJ
CO
                                                                             Transects For Phosphorus
                                                                             Concentration Gradient
                                                                             Calculations
                 Figure 55.   Transects for  phosphorus  concentration gradient calculations.

-------
      To estimate the P input  into the central basin from the western
basin between  consecutive  cruises,  the product of the  average P  con-
centration,  the flow  rate  into the central basin, and the time elapsed
between the two cruises we're  utilized.  A similar  procedure was used
to estimate the between cruise quantity of P  moving from the central
basin and into the eastern basin.

      The estimated  quantities of P entering and  leaving the central
basin were  calculated,  neglecting the flow vector and  limiting the P
distribution in and out of the basin to a vertical  epilimnion transect.
Consequently these estimates of input and output  were questioned relative
to the actual expected quantities of P transported within the lake.  The
estimated input to the central  basin at transect 1  should  represent ap-
proximately +  5 percent of the actual quantities since  the flow  rate is
relatively high and uniform throughout the transect with insignificant
backflow expected.   The conditions at transect 6  are  more complex.
The flow  velocity and the  concentration of P  (due to point sources  and
the flow from  the  western basin) is highest along the  southern  shore-
line,  while  the reverse is true along the northern  shore.   Eastern basin
water of lower P concentration may  entrain into  the central basin, which
further complicates  the flow at transect 6.   From unpublished  data and
measured concentrations of P  taken in the vicinity of  transect 6,  an
error of +  10  percent was estimated.  Consequently the calculated quan-
tity of TP retained in the central  basin has an estimated deviation of +
3 to  + 4 percent.  Good agreement was found when the P retention esti-
mates for the  western  and central  basin  were compared with those of
Burns (1976)  who utilized  more extensive  procedures  to estimate reten-
tions.  Thus,  the  simplified procedure was considered to be satisfactory.

      The mean epilimnion P concentrations for transects 1  and 6  pre-
sented in Table 28 are used for calculating TP inputs and outputs  to
and from the  central basin for cruises 1 through 6 during  1975.   In ad-
dition, the  estimated TP  concentrations for transects  2 through 5, and
the estimated  mean  volume-time weighted TP concentrations  for  cruise
1 to  6 for each transect are  presented in Table  28.   The estimated
epilimnion TP  concentrations for each  cruise at  each  transect are
plotted in Figure 56.   The concentration for  each cruise was considered
to  be 1OO percent at transect  1  and the concentrations at the succes-
sive  transects  (2 through  6) were expressed  as a percent of  the  con-
centration at  transect 1 .   The low concentration  at transect 2 is the
result of the  estimation procedure  and may not represent actual  con-
ditions.   High TP concentrations and high flow rates  occurred  along
the south shore at transect 2  and an entrainment of low TP water
occurred in the northern central part of the  transect.  Consequently
                                   139

-------
TABLE 28.   AVERAGE PHOSPHORUS CONCENTRATION  IN LAKE ERIE
       CENTRAL BASIN AT TRANSECTS 1  THROUGH 6 IN PPB
^"""""•---^Tj^ansect No.
Cruise NoT"""" 	 ~-»^
1
2
3
4
5
6
1 —* 6
1
48.21
29.64
24.92
29.27
32.40
34.93
32.15
2
20.52
9.93
12.29
15.61
19.61
27.60
17.06
3
28.75
13.01
11 .40
22.77
19.66
29.28
19.87
4
24.27
14.25
14.50
12.90
19.37
39.50
19.88
5
18.23
11.03
13.18
10.67
18.56
29.93
16.45
6
19.84
13.52
12.37
10.51
17.20
27.34
16.26

-------
no
90
70
50
         WEST
    LEGEND

        Average
      o Cruise I
        Cruise 2
        Cruise 3
        Cruise 4
        Cruise 5
        Cruise 6
        Idealized
Concentration Gradient
30
        Figure 56.   Epilemnetic phosphorus  concentration gradient  for
                      Lake  Erie  central basin.

-------
it  was felt that the calculation procedure  led to a significant under-
estimation of the  average phosphorus  concentration at transect 2.  A
similar but less significant effect influenced  transects 3,  4 and 5
during cruise 1, 2, 3  and 5.   During cruise 4 (late  August) a peak
concentration occurred at transect 3 which was  attributed to anoxic
regeneration in and around grids 38 and 41  prior to  cruise 4.   The
high concentration of TP  at transect 4 during cruise  6 appeared  to
be the result of resuspended PP and SRP from the sediments  and
interstitial water  during  the fall  storms.  The idealized  TP  concen-
tration gradient from  transect  1  through 6 is represented by the
solid curve (Figure 56).  The sharp decrease between transects 1 and
3 is largely  attributed to settling of PP which  enters the central basin
from the  western  basin.

     Burns' (1976)  Exchange Model procedure was followed for  estima-
ting  the epilimnion budget.  The quantity  of phosphorus transported
to  the epilimnion  by the  hypolimnion volume  incorporation  was obtained
by the product:

                          AVh     x      Cpa

where AVn = Vn(n-1) - Vn(n) and AVn is the hypolimnion volume
decrease  between  cruise n-1 and n, and V (n-1),  V.  , .  are the corre-
sponding hypolimnion volumes; Cpa  is the average area—weighted upper
hypolimnion phosphorus concentration  of cruise n-1 and n.

     The  quantity of phosphorus transported to the  epilimnion out of the
hypolimnion by  the exchange process with no associated hypolimnion
volume change (Pe) was  calculated by the equation:

                          Pe = APg (

where APg is the  mean area-weighted phosphorus concentration gra-
dient through the  mesolimnion, He  is  the heat transferred into the
hypolimnion by  the exchange process with no associated hypolimnion
volume change and A~l~g is the  mean area-weighted mesolimnion tem-
perature gradient.  The  area weighted phosphorus concentrations were
calculated using the same calculation  procedure used to determine the
volume weighted concentrations,  but instead of volumes,  the areas of
the particular grids were used.  The  He  and ATg were calculated by
J.  Zapotosky for  estimates of  heat  transfer.  Generally,  the concen-
tration of nutrients in  the hypolimnion is  greater  than the  epilimnion
concentration and  the  Exchange Model can be used to estimate the
transport of  nutrients to the mesolimnion and/or  epilimnion.
                                  142

-------
PHOSPHORUS BUDGET

      As stated earlier,  the  phosphorus budget presented  in this report
does  not include the contribution of P  from precipitation or apatite
phosphorus  contributed from shoreline erosion.   The budget  is  a net
budget;  thus,  the  quantity transferred  into and out of any lake compart-
ment  in  equal  amounts is not taken into  account.

      The equation used  to estimate the loss or gain of Phosphorus  in
the lake water:

                 In - Out = Accumulation
and
                 In - Out = Accumulation = Imbalance

1973  TOTAL  PHOSPHORUS  BUDGET

      During the 1973 cruise season (Table 29)  three "nutrient  cruises"
were  conducted.  Total  phosphorus data  used to estimate the 1973
western  basin phosphorus budget for the 90-day cruise  period (cruises
2-7) are presented  in Table  30.  Diffuse sources accounted  for only
1 .2 percent of the total  external phosphorus loading to  the western
basin during this  period.  This low contribution from diffuse sources
was typical for the summer  and fall months when tributary flows
were  low.   From  cruise 2 to  5,  63.8 percent of the total P  input to
the western basin  remained  in the basin due to settling,  while  34.5
percent  was transported  into the central basin.   The remaining 1 .7  per-
cent stayed in the western basin water mass.   Between cruises 5 and  7,
30.1  percent  of the loading to the western basin settled,  45.6  percent
was transported into the central basin and 24.3 percent remained  in the
water mass.   Comparison of the  quantities of total  phosphorus settled
to the quantities of phosphorus retained  in the water mass during  cruises
2-5 and  cruises 5-7 reveals a striking difference.   From cruise 2 to 5,
the percent of TP settled was large,  while from  cruise 5 to  7, a larger
percentage  was retained  in the water mass.  The large percentage set-
tled from cruise  2  to 5  resulted from the settling of resuspended  ma-
terials.  Cruise 2 followed a period of high winds  in the western  basin
causing  the resuspension of  large  quantities of  particulate matter.   This
was evidenced by the presence of  the  largest quantities of pheopigment
encountered during  the entire study period.  The 2-5 cruise  interval
indicated a sharp increase in biological  activity when the chlorophyll a_
concentration  increased  3.5 xjg/l.   During the time  interval  of  cruises
5-7,  there  was a large  increase of P in the water and less net settling,
and no  change in corrected chlorophyll a was apparent.   At the time
                                   143

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TABLE 29.  "CLEAR"  NUTRIENT CRUISE TIMETABLE
Year
1973


1974





1975





Date
7/17-7/24
8/29-9/4
10/14-10/24
4/25-5/4
6/1-6/10
6/28-7/7
8/12-8/19
8/26-9/7
10/21-11/1
3/27-4/25
6/9-6/19
7/13-7/21
8/30-9/5
9/27-10/6
12/2-12/14
Cruise No.
2
5
7
2
4
5
7
8
10
1
2
3
4
5
6
Days between
cruises

42
48

36
28
44
16
56

51
33
49
28
65
Period/
Days


90





180





226

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   TABLE 30.  LAKE  ERIE WESTERN BASIN
TOTAL  PHOSPHORUS BUDGET (METRIC TONS)
          JULY 17-OCTOBER 24, 1973
Cruise Interval
Cruise No .

2-»5
5-»7
2-> 7
2-»7
Days

42
48
90
In to W.B.

+ 1679
+ 1707
+3386
Out to C.B.

- 579
- 778
-1357
From total input
retained in Wes-
tern Basin 59.92%
Changes
in Water
Mass

+28
+415
+443
Net
Settling

-1072
- 514
-1586
Net
Regeneration

-
"

In the
Water Mass
Cruise No.
2
5
7
Metric Tons
648
677
1091


-------
cruise 7  was made (mid October),  severe storms and high wind condi-
tions existed.   These  conditions resulted in the resuspension of sedt-
mented particulate matter,  thus contributing appreciably to the high P
in the water and  low settling rates.

      Another source of P to the water mass could have been supplied
during later August-early September (cruise 5) when anoxic conditions
prevailed throughout much of the central  basin  and possibly the  western
basin.  The concentration of TP could have increased due to the regen-
eration of SRP from the sediments.  Generally,  stratification is not
observed  in the western basin;  however,  an ephemeral  stratified condi-
tion may  develop.  A  thin hypolimnion in the western basin will become
anoxic in a short period due to the  high organic  content of the sediment
and  will result  in high oxygen depletion  rates.   An alternate mechanism
for the development  of anoxic conditions in the western basin  at the
sediment-water interface, the oxygen transfer  rate to the  interface may
become lower than the depletion rate, thus causing the formation of an
anoxic layer above the sediments.   Either  mechanism may occur only
at zero or  slow wind speeds, but regardless of the  mechanism, entry
of P into the water  mass from the  sediment will result.   Occasionally,
bottom water samples with  unusually high  phosphorus concentrations
were taken in the western basin, which  substantiate a mechanism of
phosphorus regeneration in  the  basin.  The western basin  budget for
the entire 1973 cruise period shows that  59.9  percent of the total phos-
phorus loading  into the western basin was retained in the  sediments,
and  consequently  there was a substantial  quantity of phosphorus  available
to the water mass through anoxic and/or physical regeneration.

      For the entire 1973 cruise season  (cruises 2-7),  46.8 percent of
the external P loading entering  the  western basin settled  in the  western
basin and  13.1  percent remained in the  water  mass.  The central basin
received 40 percent  of the external  loading to  the western basin, which
indicates  that the western basin served as  a sink for nearly 47  percent
of the total P loading.

      The  1973  central  basin total phosphorus budget (Table 31)  showed
a net settling of 546 metric tons from cruises  2-5,  while  from  cruises
5-7,  a net  regeneration of 2,571  metric tons took place.  This  high
regeneration is attributed to the extensive anoxic hypolimnion  (11,270
km2) and physical regeneration due  to sediment resuspension during
cruise 7 storm conditions.   The internal loading  from cruise  5  and  7
due  to regeneration exceeded the external  loading  during this period
by  1,545  metric tons.
                                  146

-------
  TABLE 31.   LAKE ERIE CENTRAL BASIN
TOTAL  PHOSPHORUS BUDGET (METRIC TONS)
         JULY 17-OCTOBER 24, 1973
Cruise Interval
Cruise No.
2-> 5
5— »7
2— >7
Days
42
48
90
In From
W.B.
+578
+778
+ 1356
Point
Sources
+226
+241
+467
Diffuse
Sources
+24
+ 7
+31
Out to
E.B.
-229
-314
—543
2 — >7 From Total input retained
in central basin 70.71 %
Changes
in Water
Mass
+ 53
+3283
+3336
Net
Settling
-546
Net
Regen-
eration
+2571
+2025

In the Water Mass
Cruise No.
2
5
7
Metric
Tons
4505
4557
7840



-------
 Thus during anoxia,  the central basin became  a source of phosphorus
 instead of a sink.   The central basin budget also showed 70.7 percent
 of the 1973 external phosphorus loading to the central  basin  was re-
 tained within the basin.  The combined  central and  western basin budget
 for 1973 (cruises 2-7, Table  32) showed a net  internal loading (regene-
 ration) of 438 metric tons  with ,86  percent of the total  external  loading
 being retained  in the  western and central basins.

 1974 BUDGET

     The 1974 western basin total phosphorus  budget  is  shown  in
 Table 33.   The  peak external  total  phosphorus  loading  to the western
 basin occurred  between cruises 2-4.   The main total phosphorus
 loading enters the western  basin from the Maumee,  Detroit and  other
 rivers  during spring  run-off.  At this time 1,708 metric tons or
 47.4 metric tons/day of P  was released into  the western basin,  of
 which 1,437 metric tons, or 84.1 percent, of the external loading
 settled in  the western basin.  In  late spring and summer external
 loading decreased and reached a minimum of 34.1 metric tons/day
 between cruises  7 and 8.   A decrease in settling was observed dur-
 ing the summer  with the  cruise 7 to  8 period having a  net settling
 of only 55 metric tons.   This period coincided with  the time  of  maxi-
 mum anoxia and regeneration  in the central basin, thus the low  net
 settling may have resulted  from regeneration  of P in the western basin.
 This  phenomenon was  previously discussed in conjunction with the  1973
 western basin total  phosphorus budget.   During the fall cruises 8
 through 10,  net  settling again  increased  with  62.1 percent of the
 external loading  being retained within the basin.  As in 1973,  the
 western basin acted  as a P  sink with 59.1 percent of the total exter-
 nal phosphorus  loading retained in the western  basin during the 1974
 season  (cruises  2-10,  Table 33).

     The 1974 central basin  total phosphorus budget (Table 34) showed
 a considerable decrease  of  external loading from the spring through
 the summer months.   The external  loading decreased from 27.4 metric
tons/day between cruises 2  and 4 to 22.1  metric tons/day between
 cruises 7 and 8  with  a particularly  large decrease of diffuse  source
 loading apparent.  Net settling showed a slight  increase from  spring
through the early summer (cruise 2  to 7).  From cruise 7 to  8  there
was  an increase of  2,OO5 metric tons of P in the water column due to
an estimated regeneration of 1,723 metric tons of P.   This increase
of P coincided with the maximum extent  of anoxia during 1974, with
an estimated anoxic hypolimnion area of  10,250  km2.   The budget
showed 1,820 metric tons of total phosphorus  settled and 67.4 per-
cent of the total  external  phosphorus loading  was retained in the
                                  148

-------
                     TABLE 32.  LAKE ERIE WESTERN PLUS CENTRAL BASIN
                          TOTAL PHOSPHORUS  BUDGET(METRIC TONS)
                                    JULY 17-OCTOBER  24,  1973
10
Cruise Interval
Cruise No.
2-> 5
5-»7
2 ->7
2— »7
Days
42
48
90
In
1929
1955
3884
Out to
E.B.
-229
-314
-543
From total input
retained in western 86.02%
and central basin
Changes
in Water
Mass
+ 81
+3698
+3779
Net
Settling
-1619
Net
Regeneration
42057
+ 438
In the
Water Mass
Cruise No.
2
5
7
Metric Tons
5153
5234
8931





-------
                            TABLE 33.   LAKE ERIE  WESTERN BASIN
                          TOTAL PHOSPHORUS BUDGET (METRIC TONS)
                                   APRIL 25-NOVEMBER  1,  1974
Cruise Interval
Cruise
No.
2— »4
4-* 5
5 — »7
7— » 8
8—10
2 — 10
Days
36
28
44
16
56
180
In to W.B.
1708
1O11
1517
546
1862
6644
Out to C.B.
- 581
- 432
- 725
- 271
- 705
-2714
Change
in
Water
Mass
-310
- 12
+ 121
+220
-558
-539
Net
Settling
-1437
- 591
- 671
- 55
-1715
-4469
Net
Regeneration
-

Retained
%
65.98
57.27
52.21
50.37
62.14
59.15
In the Water Mass
Cruise
No.
2
4
5
7
8
10

Metric
Tons
1056
746
734
855
1075
517

tn
o

-------
   TABLE 34.  LAKE  ERIE CENTRAL BASIN
TOTAL  PHOSPHORUS BUDGET (METRIC TONS)
         APRIL 25-NOVEMBER 1, 1974
Cruise Interval
Cruise
No.

2— "4
4 — »5
5 — -7
7 	 »8
8— *10
2—10
Days

36
28
44
16
56
180
In From
W.B,

+581
+432
725
+271
+705
+2714
Point
Sources

+206
+ 147
+217
+ 81
+262
+913
Diffuse
Sources

+ 198
+ 17
+ 33
+ 2
+ 8
+258
Out to
E.B.

-372
-198
-252
- 72
-371
+1265
Change
in
Water
Mass

-218
-501
-323
+2O05
-163
+800
Net
Settling

- 831
- 899
-1046
-
- 767
-1820
Net
Regen-
eration

-
-
-
+ 1723
-

Retained
o/
/o

62.23
66.78
74.15
79.66
61 .95
67.44
In the
Water Mass
Cruise
No.
2
4
5
7
8
10

Metric
Tons
5247
5030
4528
4205
6209
6046


-------
 central  basin during  the  period  from cruises 2-10.   During the 1974
 cruise season, 69.8  percent of  the external loading to the central
 basin originated  from the western basin, while the remaining loading
 was  contributed by diffuse  and point sources.   The combined  western
 and central basin budgets (Table 35)  showed an  estimated 83.8 percent
 of the total external  phosphorus loading was retained  in the two basins.

 1975 BUDGET

      The 1975 cruise season extended over 226 days, or 62 percent
 of the year,  our most extensive measurement program  in terms of
 parameters and the amount of data collected.   Since  the data included
 SRP and TP as well as TSP and  PP,  the  phosphorus budget  for 1975
 has been elaborated.

      The total phosphorus  budget  for  the western basin is presented in
 Table 36.  From  cruises 1 to 2 the total  external  loading to the western
 basin was 2,206  metric  tons (43.3 metric  tons/day),  which represented
 26 percent of the  total yearly external  phosphorus loading during the
 1975 cruise season.  One thousand two hundred  ten metric tons, or
 54.8 percent of the external  loading was discharged into the  central
 basin, while  45.2 percent was considered  to have settled  in the western
 basin.   The large amount of phosphorus settled  (1,574 m tons) from
 cruises  1  to  2 was attributed to the large fraction  of  particulate phos-
 phorus entering the western basin during high spring  tributary flows  and
 to  resuspended sediments mixed into  the water mass during spring
 storms.  The external phosphorus loading  decreased  to  a low of 34.6
 metric tons/ day during  cruises 5 to 6.  From  cruises 2 through 5, the
 changes in the quantity of P  in the water mass and the  quantities of  P
 settled were  erratic.  This was attributed to the meteorological condi-
 tions during the 1975 cruise season and possible  anoxic regeneration
 from sediments by the mechanisms discussed  in connection with the 1973
 western basin total phosphorous  budget.   Fifty-three  percent  of the total
 external phosphorus loading was retained in the  western basin in the
 1975  season.

      The  1975 total phosphorus  budget for  the central basin (Table 37)
 was significantly  different from  1973 and  1974.  The  average total
 phosphorus loading to the central basin in  1974 was 21.6 metric tons/
 day and  in  1975,  24.8 metric tons/day.  This difference was attributed
 to the fraction of total phosphorus loading  retained  in  the  western basin:
 59  percent  in  1974 and 53.1 percent in 1975.  The 1975 average exter-
 nal loading decreased from a spring high of 31.7 metric tons/day (cruise
 1 to 2) to a summer low of 20.0 metric tons/day (cruise 3 to 4).  Dur-
 ing the late  fall,  the  external loading increased slightly  to 23.9 metric
tons/day.

                                  152

-------
                     TABLE 35.   LAKE ERIE WESTERN PLUS CENTRAL BASIN
                          TOTAL PHOSPHORUS BUDGET  (METRIC TONS)
                                    APRIL 25-NOVEMBER 1,  1974
Cruise Interval
Cruise
No.

2 — -4
4— —5
5 	 7
7 — -8
8 — 10
2—10
Days

36
28
44
16
56
180
In

2112
1175
1767
629
2132
7815
Out to
E.B.

-372
-198
-252
- 72
-371
-1265
Change
in
Water
Mass

-528
-513
-202
+2225
-721
+261
Net
Settling

-2268
-1490
-1717
-
-2482
-6289
Net
Regeneration

-
-
-
+ 1668
-
-
Retained
o/
/o

82.39
83.15
85.74
88.55
82. 6O
83.81
In the
Water Mass
Cruise
No.
2
4
5
7
8
10

Metric
Tons
6303
5776
5262
5060
7285
6564

en
Co

-------
                           TABLE 36.   LAKE ERIE WESTERN  BASIN
                         TOTAL PHOSPHORUS BUDGET (METRIC TONS)
                                 MARCH 27-DECEMBER  14,  1975
Cruise Interval
Cruise
No.

1— 2
2— 3
3 — -4
4 — -5
5 — »6
1 — ,6
Days

51
33
49
28
65
226
In to W.B.

42206
• 41305
+ 1721
+ 1044
+2251
+8527
Out to C.B.

-1210
- 504
- 686
- 447
-1153
-4000
Change
in
Water
Mass

-578
+325
-193
+105
-163
-5O4
Net
Settling

-1574
- 476
-1228
- 492
-1261
-5O31
Net
Regeneration

-
-
-
-
-

Retained
01
/o

45.15
61 .38
6O.14
57.18
48.78
53. 09
In the
Water Mass
Cruise
No.
1
2
3
4
5
6

Metric
Tons
1338
760
1085
893
997
835

en

-------
                            TABLE 37.  LAKE ERIE CENTRAL BASIN
                         TOTAL PHOSPHORUS BUDGET (METRIC TONS)
                                    MARCH 27-DECEMBER  14,  1975

Cruise Interval
Cruise
No.

1 — • 2
2 — »3
3 — >4
4 — »5
5 — .6
1 	 .6

Days

51
33
49
28
65
226

In From

W.B.

+1210
+ 504
+ 686
+ 447
+1153
+4000
Point
Sources

+ 277
+ 160
+ 231
+ 151
+ 312
+ 1131
Diffuse
Sources

+ 131
+ 66
+ 64
+ 123
+ 85
+ 469


Out to
E.B.

- 531
- 245
- 297
- 206
- 781
-2060
Change
in
Water
Mass

-2572
+ 386
- 27
+ 1246
+348S
+2522


Net
Settling

-3659
- 99
- 711


-1019

Net
Regen-
eration




+ 731
+2719



Retained
o/
/o

67.18
66.44
69.72
71 .43
49.61
63.21
In the
Water Mass
Cruise
No.
1
2
3
4
5
6

Metric
Tons
7101
4529
4915
4888
6134
9623

en
en

-------
     The  central basin net settling from cruises 1 to 2 was  3,659
 metric tons, which was more than twice the total phosphorus loading
 during this  period.   The source of the large quantity of  P settled was
 attributed to the particulate phosphorus  resuspended during the winter
 and early spring storms  plus particulate phosphorus  which entered
 from the western  basin and tributaries.  The relatively small quantity
 of  phosphorus settled during  the cruise  2 to 3  period was due to the
 scarcity  of  particulate matter in  the  water column at this time.   The
 epilimnion concentrations of PP,  chlorophyll a, and POC  were the
 lowest encountered in 1975.   During  this period the central  basin
 hypolimnion concentration of  total  phosphorus was nearly twice the
 concentration of the epilimnion, due to settling PP concentrating in
 the hypolimnion.   The period  from cruise 2 to 3  coincided with the
 decline of the vernal diatom  pulse and should have been accompanied
 by  considerable settling.   If  the rate of phosphorus re-entry into
 the water from the sediments is  balanced  by the sedimentation rate
 of  phosphorus from the plankton, these quantities  will not appear  in
 the phosphorus net budget,  resulting  in apparent  low net  settling.
 During cruise period 4 to 5 the net  regeneration of 731  metric tons
 of  P  was considered  to be  a  result of anoxic hypolimnion regeneration.
 The small 1975 anoxic  regeneration  coincided with the small anoxic
 hypolimnion  area of 4OO km2 compared with the larger anoxic hypo-
 limnion,  11,270 km2  and 10,250 km2  in 1973  and 1974 respectively.
 The area of anoxic hypolimnion in 1975  was suspected to have been
 underestimated due to reoxygenation of the  hypolimnion during cruise
 4.   Nevertheless,  the relationship of anoxic phosphorus  regeneration
 to  the anoxia was  apparent.

    The large amount of  total phosphorus re-entry into the water  mass
 from  cruises 5 to 6 was  attributed to physical  regeneration.  The Nov-
 ember and  December storms  as well as convection currents  caused by
 rapid cooling of surface water  were  responsible for resuspension of
 particulate and sediment  interstitial water.   Since large quantities
of phosphorus  were regenerated by physical  processes, an attempt
 was made to estimate the net quantities resuspended  in water during
 cruises 5 and 6.   Concentrations,  ratios,  and quantities of chlorophyll
 a,  pheopigment, particulate organic carbon  and PP used  for  the esti-
 mates are presented  in the Chlorophyll section.  It was  estimated that
 approximately 38 percent of the total particulate organic carbon  in  the
 water was resuspended  from  the sediment.   Approximately 50 percent
 of the total  particulate phosphorus in the central  basin water was  esti-
 mated to  have been resuspended from  sediments,  of which approximately
 18  percent of the resuspended particulate phosphorus was  in  the inorganic
 form.
                                  156

-------
      The 1975  central basin phosphorus budget showed a total loading
(external  plus internal) of 9,050 metric tons, of which 731  metric tons,
or 8.1 percent,  was attributed  to anoxic regeneration  and  2,719 metric
tons, or 30.0 percent, to oxic  regeneration.   Of the  5,6OO metric tons
of P  contributed by external loading,  3,540 metric tons, or 63.2 percent,
were retained in the central basin.

      The 1975  western plus central  basin  total phosphorus budget
(Table 38) showed  a total phosphorus loading  (external plus internal)
of 11,824 metric tons, from which 239 metric tons, or 20 percent,
was  attributed to net anoxic regeneration and 1,450 metric tons,  or
12.2  percent, was attributed to net physical regeneration.   It  was de-
termined  that 8,064 metric tons,  or 79.7  percent, of  the  10,127  metric
tons of external loading were retained in both basins.   When the  1975
western plus central basin total phosphorus budget was extended over
the whole year  it was obvious  that the anoxic regeneration  accounted
for considerably less than 2.0  percent of the external plus internal
loading.   This  was a small quantity  compared to the  total phosphorus
loading.

Budgets of Phosphorus Forms

      The forms of P (SRP, SOP and PP) were used  to develop  a bud-
get for each cruise in 1975 (Tables 39-45).   The budgets  show the
transport of P  between compartments, the transformations  of one P  form
to another and  some mechanisms of  the transformation and transport.
On Tables 39,  41, 43, 44,  45, 46, and 47, the  tabulated values  showing
the various forms  of P appear  with a plus or minus sign  in the  im-
balance column.  A phosphorus form appearing with a plus indicates
that  a transformation from  that phosphorus form  to another has occurred.

      From cruises 1 to 2, a net imbalance of SRP and SOP  of  +215
metric tons appeared and was  attributed to biological uptake during
that  period.   It  was conjectured that  through  a net assimilation of
soluble reactive and soluble organic  phosphorus by living organisms,
these soluble  forms of P  were  converted to particulate phosphorus.
A similar situation was observed from cruises 2 to 3 when 36O metric
tons of SRP +  SOP were considered  to have  been converted to PP.
The  cruise  2  to 3  ipilimnion-hypolimnion budget  indicated that assimila-
tion  occurred primarily in the  epilimnion.   This  assimilation of 360
metric tons of  SRP + SOP, with the accompanied 598-metric-ton in-
crease of PP,  indicated a considerable increase in biological activity
from the  cruise 1  to 2  interval to the 2 to 3 interval.   An increase
in corrected chlorophyll 
-------
                    TABLE 38.   LAKE ERIE WESTERN  PLUS CENTRAL  BASIN
                          TOTAL PHOSPHORUS BUDGET (METRIC TONS)
                                 MARCH 27-DECEMBER 14, 1975
Cruise Interval
Cruise
No.

1 — -2
2 — 3
3 — "4
4 — »5
5—* 6
1 	 »6
Days

51
33
49
28
65
226
In

+2614
+ 1531
+2016
+ 1318
+2640
10127
Out to
E.B.

- 531
- 245
- 297
- 206
- 781
-2060
Change
In
Water
Mass

-3150
+ 711
- 22O
+ 1351
+3325
+2017
Net
Settling

-5233
- 575
- 1939


-6050
Net
Regeneration




+ 239
+ 1458

Retalnec
o/
/o

79.69
84.00
85.27
84.37
70.51
79.66
In the
Water Mass
Cruise
No.
1
2
3
4
5
6

Metric
Tons
8439
5289
6000
5781
7132
10458

CO

-------
          TABLE  39.   LAKE ERIE CENTRAL BASIN
         1975 PHOSPHORUS BUDGET, METRIC TONS
CRUISE  1-
In from
^






In from V.'.B.
SOP- 237
SRP- 121
PP = 852
TP -1210




Cruise 1
In Water:
SOP- 648
SRP» 588
PP. 5865
TP . 7101


Point Diffuse Total
Sources Sources In
Sp" 57
IP " H4 27 141
TC " 21°
, TP ' 277 131 408
Cruise 2
In Water:
SOP. 650
SRP- 770
PP - 3109
TP - 4529


Cruise l-» 2

SOP-
SRP-

2
182
PP - -2756
TP . -2572






Out to E.B.
t> ^t-
SOP. 99
SRP- eg
pp = 377
TP - t31




                                      3659

In from W. B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settled
Imbalance
PP
+852
+210
-374
-2756
-3659
-215
SOP
+237
+ 57
- 99
4 2
-
4193
SRP
+121
+ 141
- 58
+ 182
-
+ 22
SOP+ SRP
+358
+ 198
-157
+ 184
—
+215
TP
+ 1210
+ 408
- 531
-2572
-3659
0
                              159

-------
              TABLE 40.   LAKE ERIE CENTRAL BASIN
              1975  PHOSPHORUS  BUDGET, METRIC TONS
Cruise 2
In
From:
Point   Diffuse  Total
Sources Sources  In
                                          SOP.




.^n from W.B.
' *
SOP. 39
SRP. 82
PP. 384
TP. 505















SRP
PP " ^
v TP! lft,
EPI & MESO
Cruise 2
T U_A
In Water:

SOP. 430
SRP- 528 Cruise 2 	 >3
PP - 1932 SOP. 28
TP - 2890 SRP. .173
PP - 249
TP . 104
Hypo Volune |
Incorporation: Exchange:
SOP- 29 SOP. o
SRP- 32 SRP. 7
PP. 155 PP. 51
TP. 216 TP. 58
WPO
Cruise 2
In Water:
SOP. 220
SRP. 242
PP . 1176
TP . 1638 Cruise 2 — »3
SOP. -29
SRP. .39
PP. 350
TP . 282
32
9 77
117
66 226

Cruise 3
In Water:

SOP- 453
SRP. 355
PP - 2181
TP- 2994


V
Settling
PP- 656


Cruise 3
In Water:
SOP- 191
SRP- 203
PP- 1526
TP . 1920









^Out to E.8.
*
SOP. 22
SRP. 60
PP- 163
TP. 24-5















                                       P.
                                    160

-------
 TABLE 41 .   LAKE ERIE CENTRAL BASIN
1975 PHOSPHORUS BUDGETS, METRIC TONS
                CRUISE  2-3


EPILIMNION AND MESOLIMNION
In from W.B.
In from Point & Diffuse Sources
Loss or Gain of Volume
Exchange
Out to E.B.
Settled
Accumulated in Water
Imbalance
HYPOLIMNION
In from EPI
Loss or Gain of Volume
Exchange
Settled
Accumulated in Water
Imbalance
TOTAL
In from W.B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settled
Imbalance
PP


+384
-1-117
+ 155
+ 51
-163
-656
+249
-360

+556
-155
- 51
- 99
+350
0

+384
+117
-163
+598
- 99
-360
SOP


+39
+32
+29
0
-22
-
+28
+50

_
-29
-
-
-29
0

+39
+32
-22
-
-
+49
SRP


4 82
+ 77
+ 32
+ 7
- 61
—
-173
+310

_
- 32
- 7
-
- 39
0

+ 82
+ 77
- 60
-212
-
4311
SOP&
SRP

+ 121
+109
+ 61
+ 7
- 83
-
-145
+360

—
- 61
- 7
-
- 68
0

+ 121
+ 109
- 82
-212
-
+360
TP


+505
+226
+216
+ 58
-246
-656
+ 104
G

+656
-216
- 58
_ 99
+282
0

+505
+ 226
-245
+387
_ 99
0
                       161

-------
               TABLE  42.   LAKE  ERIE  CENTRAL BASIN
              1975 PHOSPHORUS  BUDGET,  METRIC TONS
Cruise 3
In
From:
Point   Diffuse   Total
Sources  Sources   In






In from W.B. ^
SOP. 63
SRP- 103
PP - 520
TP- 686









































>


















4
1
1
1
1
A
SOP-
SRP- 94
PP -
v TP • 231
EPI & MESO
Cruise 3
in Water:

SOP. 458
SRP- 355 Cruise 3 — > 4
PP - 2181 SOP- 51
TP . 2994 SRP. 317
PP - 341
TP- 709
f A 7T
Hypo Volume
Incorporation: Exchange:
SOP. 38 SOP- 0
SRP- 55 SRP- 23
PP - 240 PP . 68
TP - 333 TP . 91
A- JL
HYP3
Cruise 3
In Water:
SOP. 190
SRP. 209
PP . 1521
TP . 1920 Cruise 3— »4
SOP. -51
SRP. 64
PP _
rr--748
TP--736
I f v
I
1
1 PP
SRP. 62 ! SRP. 129 "840
1
A
4
15 10
14
64 29

Cruise
T_ L/ai-
in Wats
SOP-
SRP.
PP . 2
TP- 3


w

Settling
PP- 300


4

Cruise 4
In Water:
SOP- 139
SRP- 273
PP- 772
TP . 1184



|
1
4
I
I
1
|
1
i
0
9
6
5

4

r:
510
672
522
704


V
1
1
1














r



*- 62

r






Out to E.B.
SOP. 42
SRP. 83
PP - 172
TP -296




























            SRP- 191
                                       162

-------
           TABLE 43.  LAKE ERIE CENTRAL BASIN
          1975  PHOSPHORUS  BUDGETS,  METRIC  TONS
                           CRUISE  3-4



EPILIMNION AND MESOLIMNION
In from W.B.
In from Point & Diffuse Sources
Loss or Gain of Volume
Exchange
Out to E.B.
Settled or Regenerated
Accumulated in Water
Imbalance
HYPOLIMNION
In from EPI
Loss or Gain of Volume
Exchange
Settled or Regenerated
Accumulated in Water
Imbalance
TOTAL
In from W.B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settled or Regenerated
Imbalance

PP


+520
+146
+240
+ 68
-172 ^
-399~62
+341
-

+399
-240
- 68
-840
-749
-

+520
+ 146
-172
-407
-901


SOP


+63
+40
+38
-
-42
-
+ 51
+48

-
-38
-
—
-51
+ 13

+63
+40
-42
0
-
+61

SRP


+ 103
+109
+ 55
+ 23
- 83
+ 62*
+317
- 48

-
- 55
- 23
+ 129
+ 64
- 13

+ 103
+109
- 83
+381,
+ 129+62
- 61


SRP

+ 166
+ 149
+ 93
+ 23
-125
+62*
+368
-

-
- 93
- 23
+ 129
+ 13
—

+ 166
+ 149
-125
+381
J-CO*
+ 1 29+62


TP


+686
+295
+333
+ 91
-296
-399
+710
—

+399
-333
- 91
-711
-736
—

+686
+295
-297
- 26
-71 0

^Regenerated from and settled to unstratified areas.
                                  163

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          TABLE 44.   LAKE ERIE CENTRAL BASIN

         1975 PHOSPHORUS BUDGET,  METRIC TONS

CRUISE    4—> 5
In from Point Diffuse Total
CAO Sources Sources In
sc°. 39
*?• 67 23 90
PP- £
^ TP . 15! 12j 274






In from W.8.

SOP. 30
SRP. 97
PP . 321
TP . 448




Cruise 4
In Water:
SOP. 648
SRP- 945
PP. 3295
TP - 4888




Cruise 4 —
SOP. .3
SRP. -133
PP . 1382
TP » 1246
1
Cruise c
In Water:
SOP. 645
SRP. 812
PP- 4677
TP «= 6134




-»5











Out to E.B.

b *•-
SOP. 28
SR?= 24
PP- 153
TP . 205





                                  p  =
                                   SR
729

In from W.B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settled or Regenerated
Imbalance

+ 321
4 145
- 153
+1382

-1069
SOP
+ 30
-r 39
- 28
- 3

-f 44

+ 97
+ 90
- 24
- 133
+ 729
+ 1025

+ 127
+ 129
- 52
- t36
+ 729
+ 1069
TP
+ 448
+ 274
- 205
41246
+ 729
0
                               164

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           TABLE 45.   LAKE ERIE CENTRAL BASIN

          1975 PHOSPHORUS BUDGET,  METRIC TONS
CRUISE

n .rom


^





In fror. W.B.
SOP. 69
SRF. 283
PP. 801
TP. 1153




Cruise 5
Ir. Water:
SOP- 645
SRP. 812
PP-4677
TP - 6134


Point Diffuse Total
^j Sources Sources *nco
SRP- 127 22 149
PP- 195
TP- 312 85 397
t
Cruise 6
In Water:
SOP- 638
SRP- 2481
P° - 6504
TP- 9623


Cruise 5~»6

SOP.
SRP-
PP -
TP .

-7
l6&8
1827
3488





Out to E.B.
SOP- 77
SRP- 120
PP- 585
TP- 782




                                  P  = 2720
                                   SR

In from W.B.
In from Point &. Diffuse Sources
Out to E.B.
Accumulated in Water
Settled orRegsnerated
Imbalance
PP
4-801
4195
-585
+1827
?
-1416
SOP
+69
+53
-77
- 7

+ 52
SRP
+283
+ 149
-120
4-1668
4-272O
+1364
SOP -|- SRP
+352
+202
-197
+1661
42720
+ 1416
TP
+1153
+ 397
- 782
+3488
+2720
0
                               165

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              TABLE 46.    LAKE  ERIE  CENTRAL  BASIN
             1975  PHOSPHORUS  BUDGET,  METRIC  TONS
CRUISE
                               In from
  In from W.3.
  SOP.   69
  SRP.  283
  PP =  801
  TP. 1153
                  Cruise   «j

                  In Water:
                  SOP.  645
                  SRP.  812
                  PP - 4677
                  TP = 6134
      Point     Diffuse
,,r.0   Sources   Sources
   *
                                                       312      85
                                   Total
                                   In
                                      53
                                     149
                             397
                 Cruise   £

                 In Water:
                 SOP.   638
                 SRP.  2481
                 PP -  6504
                 TP «  9623
Cruise

SOP.   -7
SRP. 1668
PP . 1827
TP . 3488
                              PP - 914
 SRP & SOP .  1806
                                                                                Out to E.B.
                                SOP.  77
                                SRP.  120
                                PP.  585
                                TP =  782

In Prom W. B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settledor Regenerated
In-, balance
PP
+ 801
4 195
- 585
+ 1827
+ 914
- 502
SOP
+69
+53
-77
- 7

+52
SRP
+ 283
+ 149
- 120
+1668
+ 1806
+ 450
SOP+ SRP
+ 352
+ 202
- 197
+ 1661
+1806
+ 502
TP
+ 1153
+ 397
- 782
+3488
+2720
0
                                           166

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                TABLE 47.    LAKE ERIE  CENTRAL  BASIN
               1975  PHOSPHORUS BUDGET,  METRIC  TONS
CRUISE
1 ->6
                                In from
                                                 _
                                                 SOP
                                                 SRP-   470
                                                 PP -
                                                 TP -  1204
                                       Point     Diffuse
                                       Sources   Sources
                                                 396
       Total
       In
         221
         566
         813
        1600
   In fro-:  W.B.
   SCF=  -*37
   s=p=  685
   pp „ 2878
                   Cruise  I

                   In Water:
                   SOP. 648
                   SRP- 588
                   PP . 5864
                   TP - 7100
                                                  Cruise  (,

                                                  In Water:
                                                  SOP-   638
                                                  SRP-  2481
                                                  PP -  6504
                                                  TP -  9623
                          Cruise 1— >6

                          SOP.  -9
                          SRP- 1887
                          PP.  644
                          TP-2522
                     A
                     1
                            3674
                                                                                   Out to E.B.
             SOP.  268
             SRP-  344
             PP - 1447
             TP - 2059
                                     1021
• 4695

In from W. B.
In from Point & Diffuse Sources
Out to E.B.
Accumulated in Water
Settled °r Regenerated
Imbalance
PP
+2878
f 813
-1447
+644
-4695
-3095
SOP
+437
+221
-268
- 9

+399
SRP
f 685
f 566
- 344
f1887
f3674
f2694
SOP+ SRP
+ 1122
+ 787
- 612
+ 1878
+3674
+3095
TP
+40OO
+ 1600
-2059
+2522
-1019
o
                                               167

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       The preliminary budget  calculations for the 3 to 4 cruise interval
 showed a net imbalance of +191  metric tons of SRP + SOP and an
 imbalance of -191  metric tons of PP.   Since the calculated  excess of
 191 metric  tons  of SRP  + SOP was assumed to be regenerated from
 the sediments, then the excess was thought to originate  in the hypolim-
 nion.   The  hypolimnion budget showed  only 129 metric tons of SRP  +
 SOP regenerated,  62  metric tons less than the total excess.   The epi-
 limnion budget indicated  a deficit of 62 metric tons of SRP +  SOP;
 consequently it was postulated  that the 62 metric tons of SRP, or 32.5
 percent of the total 191 metric tons regenerated, were transported from
 the sediment directly  into the epilimnion in unstratified areas.   During
 cruise 4 the hypolimnion covered an area of 9,6OO km2  in the central
 basin,  while the  remaining 6,49O km2,  or 40 percent, were  not strati-
 fied.   The relationship between the quantity of SRP regenerated in the
 unstratified  portion of the central basin to the actual  (unstratified) area
 appeared to  substantiate the theory  that SRP  is directly transported
 from the sediments to the unstratified  overlying  water.  The cruises
 3  to 4 budget showed  a net  191 metric tons of SRP + SOP regenerated
 and converted to PP.   Comparison  of the budgets for the 2 to 3 and
 3  to 4 cruise periods  indicates  that the conversion of SRP + SOP to
 PP  was greater during the 3 to 4 cruise interval.  This  increase  in
 biological activity was also substantiated by an  increase  of 4.6 juig/l
 of uncorrected chlorophyll a during  the  3  to 4 cruise  interval.

      The addition of 729 metric tons of SRP resulting from  anoxic
 and oxic regeneration  in the hypolimnion was  shown in the budget
 between cruises 4 and 5.   The  imbalance  of +1,069 metric tons  of
 SRP + SOP was  converted to  PP by biological assimilation.   High bio-
 logical activity was also  confirmed by a 2.3 xjg/l increase in  corrected
 chlorophyll a between  the  cruises and represented the highest chloro-
 phyll a concentration  during the 1975 cruise season.   It  should be  men-
 tioned that the estimated  figure,  1,O69  metric tons of SRP +  SOP as-
 similated, was high.   If a  fraction of the  net regenerated phosphorus
 was attributed to resuspended  PP,  the  quantity of SRP converted to  PP
 would  have been smaller.   Nevertheless, the general trend of  phos-
 phorus conversions to  various  forms in  the central basin  would be very
 similar even if more detailed  data were available.

      Table 45 shows the  net phosphorus forms budget  for cruises  5  to
 6.   The regeneration of 2,720  metric tons  of SRP + SOP and  the
 calculated quantity of SRP + SOP converted to PP appeared to be ex-
 cessive.  The overestimation of these quantities  was primarily attri-
 buted to resuspension  of PP, as  was discussed as  part of the 1975
total phosphorus budget.  Table 46 shows the  net phosphorus  forms bud-
get for cruises 5 to 6, corrected  for resuspended PP.  The corrected
                                  168

-------
budget for cruises 5 to 6 indicated a  regeneration  of 1,806 metric tons
of SRP with 502 metric  tons of SRP  + SOP converted to PP.   This
estimate suggests there  was a  considerable decrease in biological activ-
ity  during  the 5 to 6 cruise  interval,  as compared to  cruises 4 to 5.
A 3.1 pg/\ decrease in corrected chlorophyll  a concentration was further
evidence of decreased  biological  activity.

      The  phosphorus forms  budget for the entire 1975 season  appears
as Table 47.   The conversion  of 3,095 metric tons of SRP +  SOP  to
PP was not corrected  for resuspension of PP  and,  therefore,  appears
higher than the actual  conversion.

      Figures 57 and 58  show the SRP  + SOP—> PP  conversion rates
and sedimentation rates  for the 1975  cruise season.  Anoxic regenera-
tion of phosphorus and peak  biological activity during  the cruise 4 to  5
period is apparent from  both curves.

CONCLUSIONS

      The  1973  through 1975 measurement of  total  phosphorus  were com-
pared with 1970 CCIW measurements (Table 48).   The external phos-
phorus loadings to both the western and central basins were considerably
greater during  1970.   The concentrations and quantities  of TP in the
western basin during  1970 were  not significantly greater and the quantity
and concentration in the  central  basin was only slightly greater.  The
percent of TP retained in the  western basin during 1970 was the  greatest
of the three years examined.  In 1974 and  1975,  59.2 and 53.1  percent,
respectively,  of the  western basin external TP load was retained in the
basin, as  compared  with the 77  percent retained in 1970.   The percent
of the quantity of phosphorus retained in the central basin was greatest
in 1974, but not much different from 1970 or  1975.  The  quantity of TP
retained in the  combined western and central basins was greatest  in
1970  due  to the large  fraction of external loading retained in the  western
basin.  The estimated 197O  total external loadings  of P  to the western
and central basins used  by  Burns (1976) were 23,580 and  5,220 metric
tons, respectively (Table 48).   The updated U.S.  Army Corps of  Engi-
neers (1975) estimated loadings to the western and central basins  for
1970  were  17,043 and 4,501 metric tons,  respectively.  The revised
estimates, particularly for  the western basin, indicate that little  change
In total loading has taken place  from 197O to  1973.  Based on the
revised loading values for the western  basin,  the percent  of P re-
tained within the  basin Is estimated  to  be 61  percent,  which is similar
to the value for 1974 (see Overview section).   The Canada Centre  for
Inland Waters has not recalculated the  1970 phosphorus  budget based  on
the revised loading estimates (Noel Burns, personal communication).
                                   169

-------
                  SOF - Soluble Organic Phosphorus
                  SRP - Soluble Reactive Phosphorus
                  PP  - Paniculate Phosphorus
                  SOP + SRP -* PP TRANSFORMATION CALCULATED
                  FROM NET PHOSPHORUS BUDGET
             40 r
          >-
          <
          o
          Of
             10 -
                                                _      _
                  APR | MAY | JUN |  JUL |  AUG |  SEP |  OCT   NOV   DEC
           Figure 57.    Lake  Erie  central  basin  - 1975,
                         phosphorus  transformation.
Figure 58.
Regeneration and sedimentation rates of particulate
phosphorus  in  the central and  western basins of
Lake Erie -  1975.
                                   170

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              TABLE  48.   LAKE  ERIE WESTERN  AND CENTRAL  BASIN  1970-1975
              MAY  THROUGH  SEPTEMBER  (5/1-9/30)  MEAN TOTAL  PHOSPHORUS
                CONCENTRATION  AND QUANTITIES, "ANOXIC" REGENERATION,
                                   EXTERNAL  LOADING,  AND  SINK



YEAR

1970
1973
1974
1975
WESTERN BASIN
Mean 5/1 - 9/30

TP
M-Tons

895*
-
840
980

TP
Cone.
JJg/1
38.3*
-
35.4
41.8
TP
External
Loading
M-Tons
per Year
23580***
17500
166OO
14900
TP
Retained
Percent
of Input

77
-
59.2
53.1
CENTRAL BASIN
Mean 5/1 - 9/30

TP
M-Tons

5500*
-
5250
5150
TP
Cone.

17.9*
-
16.6
17.0
Area of
Anoxlc
Hypollm-
nlon km

6600
11270
10250
400
TP
Anoxlc
Regener-
ation
M-Tons
1900
2570
1720
730
TP
External
Loading
M-Tons
per Year
5220**
4000**
42OO**
3850**
TP
Retained
Percent
of Input

65
-
67.4
63.3
	 w.B. -t- C.B. 	
TP
External
Loading
M-Tons
per Year
28800
21500
20900
18800
TP
Retained
Percent
of Input

87.7
-
83.8
79.7
  *  C.C.I.W. data recalculated with the volumes used by CLEAR for 1973, 1974 and 1975.
 **  Does not Include TP entering  from  western basin.
***  Does not Include TP from precipitation.  The 1970 estimated phosphorus loading  appears excessive.

-------
       The  area of anoxia  was highly variable during the study period
 (Table 49).  In 1970 the area of anoxia was nearly half that which oc-
 curred  in  1973 and 1974, but the quantities of TP in  the central basin
 were not significantly different.  This may be attributed to the  extension
 of the anoxic period into  late September 1970,  while  in 1973 and 1974,
 turnover occurred early in  September.   In 1973 anoxic regeneration
 was overestimated, since the increase in quantity  of TP also included
 resuspended phosphorus from the sediments, attributed to  stormy weath-
 er  following turnover in 1973.

       The  1970 and 1974 data are most comparable on the  basis of
 sampling schedule.  The  quantity of phosphorus regenerated  in  1970
 was slightly greater than in 1974 despite the nearly twofold increase
 of anoxic area  in  1974.   As previously mentioned, this was attributed
 to the duration of the anoxic period.

       The  1975 estimate of  anoxic area and the quantity of phosphorus
 regenerated  associated with anoxia was underestimated.  During the
 late summer anoxic period,  the hypolimnion was reoxygenated prior
 to turnover; so the area and the phosphorus associated with anoxia were
 difficult  to estimate.

       The  1975 central basin phosphorus budget shows  that 8.1   percent
 of total phosphorus loading  (internal  plus external) was attributed to
 anoxic regeneration and 30.0 percent to oxic or physical regeneration
 (resuspension).  Similar  conditions  were observed in  1970.  In  1973
 and  1974  no measurements  were taken during December, but similar
 conditions  probably existed  in these years.   If the 1975 western basin
 and  central basin phosphorus budget  was extended over the whole year,
 the percentage of total phosphorus loading  (internal plus external) con-
tributed  by anoxic regeneration  would decrease  considerably.

       The following major conclusions were reached during the  course
 of this study:

       1.   The  1970,  1974 and 1975 nutrient monitoring surveys
           do not show significant change  in concentration and
           quantity  of phosphorus  in the Lake Erie western  and
           central  basin  water.

       2.   Physical regeneration  (resuspension)  appears to  be
           the major source  of internal phosphorus  loading.
                                    172

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               TABLE 49.   TOTAL  PHOSPHORUS  "ANOXIC" REGENERATION
                        ASSOCIATED WITH ANOXIC HYPOLIMNION
                       LAKE  ERIE WESTERN AND CENTRAL BASIN
                                   1973,  1974 AND 1975
Year
1973
1974
1975
External Total Phosphorus
Loading (Metric Tons* )
W.B.
1750Q
166QO
14900
C.B.
4OOG
42 OO
3850
W.B.&C.B.
21495
20869
18775
Total Phosphorus ''Anoxic Regenerc
W.B.
0
O
0
C.B.
2570
1720
730
W.B.&.C.B.
2571
1723
731
ation (Tone)
% of External Loading
W.B.&.C.B.
12.0
8.3
3.9
*  Corps of Engineers,  Buffalo District,  Data.

-------
      3.   Anoxic regeneration  of phosphorus  was considered of
          secondary importance as a source  of  internal  loading
          and only contributed  during the  late summer in the
          central basin.

      4.   During 1970-1975, the western and central basin
          served as phosphorus sinks.

REFERENCES

Burns, N. (ed.)   1976.   Lake Erie in the early seventies.  J.  Fish
      Res. Bd. Can.   33(3):349-645.

U.S.  Army Corps  of Engineers.   1975.   Lake  Erie  water  manage-
      ments study,  Vol. 3.  U.S.  Army,  Corps of Eng.,  Buffalo
      Dist.  Buffalo,  N.Y.
                                  174

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                             SECTION 7

   CHLOROPHYLL a  AND PHEOPIGMENT DISTRIBUTION  IN THE
         CENTRAL  AND WESTERN BASINS OF LAKE  ERIE

                  Laura A.  Fay and David E. Rathke
                 Center for Lake  Erie Area  Research
                      The Ohio State University
INTRODUCTION

      Chlorophyll  in Lake Erie's central  and western basins was moni-
tored by the Center for Lake Erie Area  Research (CLEAR) from  1973 to
1975 as a  portion of the Lake  Erie Nutrient Study sponsored by the U.S.
Environmental Protection  Agency's Large Lake Research Station at
Grosse He, Michigan  (Grant No. R-802543-01).   Chlorophyll pigments,
along with other eutrophication indicators,  were measured  to determine
if recent attempts to  impede eutrophication  by reducing  nutrient loading
into Lake  Erie  have been effective.  Water samples  collected on 15
general cruises during these three field  seasons  were analyzed  for
chlorophyll pigments.   Sampling and analysis in  Lake Erie's eastern
basin was  undertaken  by the Great Lakes Laboratory (GLL) at  Buffalo
(SUNY).

      The  major objective of this portion of the survey  was to  quantify
chlorophyll a.  and pheopigment  a  in the central  and western basins and
to observe seasonal and yearly trends  of chlorophyll concentrations.
Shoreline  versus  open lake  concentrations were also examined.   To
analyze the data,  several analyses of variance  and regression models
were used.

MATERIALS  AND METHODS

      Water samples were collected from 51 stations, 37 in the central
basin and  14  in the western basin, with  Niskin water bottles set in  series.
Depth  selections were identical to  those  for nutrient  analysis.   Water
was filtered through Whatman  GF/C glass fiber filters to which a few
drops  of MgCOs suspension were added.   The samples  were placed
in plastic  petri dishes and frozen (-8°C) until analysis.

                                  175

-------
       Filters were ground with a teflon homogenizer at 300 rpm for less
 than one minute  in 4 ml of 90 percent acetone.  The samples were
 diluted to 12 ml  and placed in a dark  refrigerator for 4 hours  before
 analysis.

     After 10 minutes of centrifugation  at 3000  rpm,  the samples were
 analyzed spectrophotometrically.   A Varian Techtron model 635 automatic
 spectrophotometer in conjunction  with  a computer was used for  sample
 analysis and  calculations.   Table  50 presents the equations used to cal-
 culate chlorophyll concentrations.   Three different equations for chloro-
 phyll a were used: Odum et al.  (1958);  SCOR/UNESCO (1966) and
 Lorenzen (1967),  chlorophyll a corrected for the amount of pheopigment.

     Calculations  of chlorophylls b and  c_, and pheopigment  a were made
 for all samples.   In addition, the ratio of  absorbances at 663 nm before
 and  after acidification (Fo/Fa ratio, Lorenzen,  1967) was determined.
 An Fo/Fa ratio of 1.7  indicates that the sample  contained  pure  chloro-
 phyll a, while a  ratio of 1.0 indicates  that the sample  was  pure pheo-
 pigment a..   Ratios falling within this range represent varying percentages
 of both chlorophyll a and pheopigment  a.  This ratio was helpful in deter-
 mining the physiological condition of the phytoplankton.

     The chlorophyll  data are expressed as  jug/I of  corrected chlorophyll  a
 or as  metric tons of corrected chlorophyll  a.  All of the data presented ~
 were volume  weighted  in accordance with the procedure outlined in the
 overview section.

Chlorophyll Standards

    Chlorophyll standards were acquired from the U.S.  Environmental
Protection Agency,  Environmental  Monitoring and Support  Laboratory at
Cincinnati, Ohio.   Comparisons of estimated  concentrations  by the  E.P.A.
and those determined by CLEAR on the Varian  Techtron are as  follows:

    Equation
SCOR/UNESCO
Chi a
Chi b
Chi c
Lorenzen
Corrected Chi a
pheopigment a
	 : 	 , 	 1
EPA
8.40 + 0.40
2.55 + 0.20
1 . 69 + 0 . 40
6 . 09 + 1.10
4.17 + 1 . 40
CLEAR
8.21 + 0.04
2.85 + 0.03
1 .50 + 0.02
5.83
4.30
                                   176

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          TABLE 50.   EQUATIONS USED FOR  LAKE ERIE
                     1973-1975  CALCULATIONS
SCOR/UNESCO (1966)

      Chi  a (vg/l)=11 .64(0.D.663-O.D.750)-2.16(O.D.645-O.D.750)
                  +0.10(O . D. 630-O . D. 750)

      Chi  b (Mg/l)=20.97(O.D.645-O.D.750)-3.94(O.D.663-O.D.750)
                  -3.66(O . D. 663-O . D . 750)

      Chi  c (pg/l)=54.22(O.D.630-O.D.750)-14.81(O.D.645-O.D.750)
                  -5.53(O . D. 663-O . D. 750)

Lorenzen  (1967)

      Corrected Chi a (Mg/l)=26.73(O.D.663-O.D.750)
                            -(O.D.663ac.d-O.D.750ac.d)

    Pheopigment a (pg/l)=26.73x1 .7(0 .D.663acid-O.D.750acid)
                         -(O . D. 663-O . D. 750)

      Fo :Fa=O . D. 663-O. D. 750/(O . D. 663acid~° •D • 750acid)

Odum et al. (1958)

      Chi  a (pg/l)=13.4(O.D.665)

*     All values must take into account the volume of the extract (ml),
      the volume of water filtered (liters) and  cuvette cell length (cm).
      These factors must all be taken into account  for the final deter-
      mination.   An example of  a complete   SCOR/UNESCO equation
      follows:

                  11 .64(O . D. 663-O . D .750)-2.16(O . D. 645-O .D .750)
      Chi  a =        +0.1O(O.D.63O-Q.D.750)xVolume  of extract
                  Volume filtered (liters) x  cuvette length (cm)
O.D. = Optical  Density.
                                  177

-------
      Chlorophyll b_ was found to be slightly higher than the EPA estimate
 Both chlorophylls a and £ fell within the estimated range.   Comparisons
 of corrected  chlorophyll a_ and  pheopigment a were also positive.

 Measurement Errors

      A  single sample of chlorophyll  was scanned  20 times at 750, 663,
 645  and 630 nm during a 30-minute period and the results analyzed for
 repeatibility.  Chlorophyll a  concentrations had a  standard deviation of
 0.01  with 0.12 percent standard deviation.   Chlorophyll t) appeared to  be
 the second most reliable determination with 0.02 standard  deviation
 (0.70 percent).  Chlorophyll £  had a 0.04 standard deviation or 3.60
 percent.

      An  error resulting from an  inaccurate absorbance reading of 0.001
 was calculated for each of the three  chlorophyll absorbance maxima.
 A theoretical measurement  error  of less than one percent  was calculated
 for chlorophylls  a_ and JD, while  the estimated error for chlorophyll c
 was 4.4 percent.  In addition the  chlorophyll £ value was also influenced
 by an error at the  chlorophyll ts absorbance.

      Less than one  percent of  the chlorophyll ^ and  c  observations had
 negative values.   It  was felt  that the negative concentrations resulted
 from errors  in absorbance  readings when low chlorophyll  concentrations
 were encountered.  Errors resulting  from extended  periods of freeze
 storage (greater than 60 days) for corrected chlorophyll a  and pheopig-
 ment a  were  estimated.  Due to the variability of the length of sample
 storage,  plus the need  for further investigations into the effects of
 storage on chlorophyll degradation and  pheopigment development, no
 attempt was made to  correct for this source of error.

 RESULTS AND DISCUSSION

      When analyzing  the  chlorophyll a  data for the 1973,  1974 and 1975
 seasons  the major emphasis was placed on generalized and long-term
 effects.   Due to the three-year  duration of the  study and lengthy inter-
 vals between  sampling cruises,  it was  felt that this overview  would
yield the  most useful information concerning the overall trends and
 regional effects since the 1970  Canada  Centre  for  Inland Waters study
(Glooschenko  et al. 1974).
                                   178

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Sub-Basin Comparisons

      Geologically, Lake Erie is divided into  western, central and east-
ern basins by glacial moraines.   The  western basin is the shallowest
of the three  basins with a mean depth of 7.4 m and represents only  5
percent of the  total lake volume.  The central  basin  has  a mean  depth
of 18.5 m and contains 63 percent of the total  lake volume (Verber,
1950).  The  relationship of basin morphometry to  the rate of eutrophi-
cation has been discussed  by many investigators.  Vollenweider (1971)
demonstrated that  similar  nutrient loadings to a shallow lake (10  m)
and to a deeper  lake (100  m) would  result in a greater increase  in
the rate of eutrophication of the shallower lake.   Sakamoto (1966) also
emphasized that  phytoplankton production was influenced by basin  depth
and attributed this influence  to  differences in availability of light  and
nutrients  in  deep versus shallow basins.

      The  shallow  western basin of Lake Erie is continuously supplied
with nutrients  from  the Detroit, Maumee, Raisin and  Portage Rivers
as well as non-point sources.   In addition to external loading,  nutrients
are regenerated  from decomposition of organic matter,  i.e.  plankton.
Thus  the  nutrient-rich western  basin maintains high concentrations of
chlorophyll a throughout the  year.

      The  deeper central  basin  is  less productive  than the western basin
throughout the year  and especially during the summer months.   Summer
standing crops in  deep lakes are generally smaller than they are  during
vernal and autumnal  circulation  periods (Sakamoto,  1966).  This can be
attributed  to the accumulation of nutrients in the hypolimnion which  are
largely prevented  from mixing  with  the  nutrient-depleted  waters of the
epilimnion.

      The  basin  effect on chlorophyll a concentrations for the western
basin  and  the central  basin  was found to be of first order importance.
Western-central  basin ratios of corrected chlorophyll a were calculated
using  volume-weighted  cruise averages (Table 51) in order to evaluate
the difference  between the basins.   The average concentrations of chloro-
phyll a in the  western  basin were usually two to three times those found
in the central  basin.  The largest basin ratios were observed during
the summer months when  the western basin reached  its maximum chloro-
phyll a concentrations and the central basin its lowest.   The lowest
western to central basin  ratios  were observed  in  the  fall  and winter
months.   For  example, during  the fall of each year,  chlorophyll a con-
centration was reduced to approximately 1 .5 times that of the central
basin.
                                     179

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 TABLE 51.  CORRECTED CHLOROPHYLL a
VOLUME WEIGHTED CONCENTRATIONS,  1973-1975
Year
1973



1974






1975







Cruise
17-23 July
29 Aug-4 Sept
14-24 October
Yearly Average
25 April-4 May
1-10 June
28 June-7 July
12-19 August
26 Aug-7 Sept
21 Oct-1 Nov
Yearly Average
27-31 March
21-25 April
9-19 June
13-21 July
30 Aug-5 Sept
27 Sept - 6 Oct
2-14 December
Yearly Average
Western
8.34
11 .74
11 .95
10.68
8.75
10.03
16.50
17.14
13.48
14.65
13.43
10.34

21.07
17.59
16.31
12.34
4.66
13.72
Central
2.40
3.38
7.87
4.55
3.47
2.63
2.41
3.82
3.76
9.45
4.26
5.09

2.71
3.11
7.72
10.05
6.92
5.93
W :
Basin
3.48 :
3.47 :
1 .52 :
2.34 :
2.52
3.81
6.85
4.49
3.59
1 .55
3.15
2.03

7.78
5.66
2.11
1.23
0.67
2.31
C
Ratio
1 .0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0

1.0
1.0
1.0
1.0
1.0
1.0
                    180

-------
      For more detailed  chlorophyll a. comparisons within the central
basin, it was subdivided into eastern and western segments.  The divi-
sion was demarcated by  a  line running south from Pointe Aux  Pins,
Ontario to slightly east of  Cleveland,  Ohio (Figure 59).  The eastern
central basin included  stations  23-29 (grids 19-31) and the western basin
stations 40-54 plus stations 65 and 74 (grids 32-43).   Cruise average
corrected chlorophyll  a concentrations for  the three sub-basins were
examined (Table 52).   The western basin normally had the  highest aver-
age chlorophyll a values ranging from 1  to 9 times the eastern central
basin average concentrations, although exceptions to  the  west-east trend
of decreasing chlorophyll a_ concentrations  did occur.   For  example, in
December  of 1975 the  western  basin was observed to have lower  chloro-
phyll  a values than the eastern  central basin (0.7:1.O).  The western
centraT basin generally had the  second highest  corrected chlorophyll  a
concentrations with the exception of early  June  1974  and early October
1975.  The three-year average  corrected chlorophyll  a_ concentrations
for each station (Table 53) also substantiate the west to  east trend
(Figures 60  and 61).   Two anomolies existed:   (1) a low concentration
area  in the western basin  east of the Detroit River mouth and (2) a
high concentration area in  the central basin extending  from the island
area  eastward along the southern shore  of the  central basin.

      Due to  high and  low  areas of concentration  within the central basin,
it was further subdivided into 3 regions  (Figure 62):   (1) shore (s),  (2)
mid-lake  (m) and (3) the Sandusky sub-basin (b), Thomas,  et  al.  (1976).
The average  corrected chlorophyll a concentrations (ug/l) of the western
basin and the designated sub-basins of the central basin  for each of the
three years  were:

                                    1973       1974       1975
      Western (wb)                 12.05      13.45      14.80
      Sandusky sub-basin (b)        6.55       9.O8       9.77
      Shore  (s)                     5.40       4.52       6.71
      Mid-lake  (m)                 3.60       3.3O       5.O8

The trend throughout the three years  was  very  consistent.   Chlorophyll
a was found  in highest concentrations in the  western  basin  followed by
the Sandusky sub-basin and the shore area,  with the mid-lake having
the lowest values,  as  demonstrated by the three-^year basin ratio:

             western     Sandusky
              basin      sub-basin     shore      mid-lake

              3.37     :    2.18     :    1.36    :    1.00
                                  181

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                                        BASIN SUBDIVISIONS USED FOF
                                          CHLOROPHYLL ANALYSIS
                                               1973-1975
    Figure 59.   Basin subdivisions used for  chlorophyll
                 analysis 1973-1975.
                                              CENTRAL BASIN
                                          SUBDIVISIONS USED FOR
                                           CHLOROPHYLL ANALYSIS
                                                1973-1975
Figure  60.
Central  basin subdivisions used for chlorophyll
analysis,  1973-1975.
                              182

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                          TABLE 52.   CORRECTED  CHLOROPHYLL a (jug/I)

                          VOLUME WEIGHTED CONCENTRATIONS,  1973-1975
oo
CO
Cruise
1973
Late July
Late August
Mid October
1974
Early May
Early June
Early July
Mid August
Early September
Late October
1975
April
Mid June
Mid July
Early September
Early October
Early December
Western
Basin

8.34
11.74
11.95

8.75
10.03
16.50
17.14
13.48
14.65

10.34
21.07
17.59
16.31
12.34
4.66
Central E
West

3.69
5.22
8.27

4.32
2.03
3.74
5.77
5.44
12.56

6.28
3.28
4.49
10.26
9.89
7.47
Sasin
East

1.75
2.37
7.65

3.01
2.54
1.68
2.76
2.84
7.74

4.44
2.40
2.36
6.33
10.14
6.62
Basin
WB :

4.77 :
4.95 :
1 .56 :

2.91
3.95
9.82
6.21
4.75
1 .89
2rtrt
.33
8.78
7.45
2.58
1.22
0.70
Ratio
WCB

2.05 :
2.20 :
1.08 :

1 .44
0.80
2.23
2.09
1 .92
1 .62
4 A A
1 ,°t 1
1.37
1.90
1.62
0.98
1.13
: ECB

1.0
1.0
1 .0

1.0
1.0
1.0
1 .0
1 .0
1.0
In
• (J
1 .0
1 .0
1 .0
1.0
1 .0

-------
                          TABLE  53.   CORRECTED CHLOROPHYLL a (jug/I)
                        STATION MEANS FOR THE 15 CRUISES, 1973-1975
oo
Station
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
Means
5.44
3.94
3.65
3.54
3.93
4.55
4.73
4.45
3.56
3.72
4.24
6.05
6.37
4.01
3.41
3.96
4.26
5.21
5.81
3.80
4.46
9.03
5.74
5.87
4.79
6.06
6.84
Standard
Deviation
4.28
3.13
2.76
2.75
3.06
2.89
2.92
3.51
2.86
2.52
3.23
4.13
3.98
3.02
2.25
2.41
3.26
2.97
3.98
3.07
3.60
4.99
4.41
4.24
3.77
3.49
4.76
Number of
Measurements
46
46
50
47
51
49
45
54
52
52
45
48
43
53
51
52
46
49
51
51
52
44
49
43
50
48
46
Station
50
51
52
53
54
55
56
57
58
59
60
61
65
66
67
68
69
70
71
72
73
74
75
76
78
79
81
Means
8.36
7.35
8.53
10.53
10.16
11.43
11 .98
14. 8O
13.66
12.93
14.30
7.47
9.21
13.29
11.15
11 .51
14.42
24.60
2.63
4.04
3.87
8.55
21 .23
20.79
3.84
3.02
20.14
Standard
Deviation
3.63
4.16
6.38
5.80
6.98
6.60
4.57
13.31
8.67
7.63
12.71
4.69
5.57
5.36
8.10
8.17
7.62
14.93
1 .72
3.53
3.50
5.15
14.25
10.56
2.99
2.41
11 .43
Number of
Measurements
43
46
46
45
45
42
45
44
39
45
45
41
46
39
46
45
20
32
10
10
51
45
31
22
45
42
39

-------
Corrected Chlorophyll a
Corrected Chlorophyll a (ug/l) _.
0 10 * °> 00 0
1 ' 	 1 	 » 	 f

•n I
to 8-
c
(D

0)
ro
•
*.
ui

0) ^S

O T
r1-Ǥ
T (D
j» ^
i—* O" -•
00 Q) -T
S jg«
fn (D o
w n 3
rf "• "i oo
O) w -
H- O
!••• T
O ~
D 0
-w 3
^T)
(0 "^
CO •"• 0
ilo> °
^£
Ol (O
l""^
or ~


m
D>
a -
3 s:
.----' 3 «Q
/• c
^-^" ro -
m****^ O»
\. 0) "^
^» _h
op f •
w m »^^^ 	
n n — 	 	 o>-

(D 2 	 	 — • —  tj ^^
C T ^ x*' ^ <
j T ~L ST y> ii
o o ^-— -. __ S; (Q s*:
a a ^X*3 O*
/ _* 2 in »~
X 5 8 1 :
N-^^ " ro^ t
~~7i» 
- ^.-__ „, Jl
^~^-~.ui a
— r+
C S
1 1 1 \\ 1 1
\\
«
• 9
»
•
* ^


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_


A
_
./•
•
* .
• :*
••
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9*
• m
*
0*
*
,*
•*
A
^


•

-------
 The three-year average chlorophyll  a concentrations for  each station
 in  the central basin showed a shore  versus mid-lake effect (Figure 63).
 For each transect across the lake,  i.e.  stations 23 to 29, the south
 shore (Station  23) exhibited the highest concentrations with a  mid-lake
 low (Station 25) and higher concentrations  on the north shore (Station 29).
 The south shore concentrations were higher than the north shore concen-
 trations with the shore stations in the western  central basin having
 higher concentrations than  those  in the eastern central basin.  Regres-
 sion analysis showed the basin subdivisions to be of first order signifi-
 cance,  accounting  for  the major  variability in the three years of data.
 The chlorophyll data  indicated that areas designated as sub-basins  were
 signficantly different and represented areas reflecting "real" differences
 in  standing crop.  These differences demonstrate the  need for a synoptic
 lake survey.

 Seasonal Trends

      Seasonal  variations of chlorophyll a_ concentrations  have been docu-
 mented by previous studies  on  the Great  Lakes.  Although each of the
 Lake Erie sub-basins  exhibited somewhat different  seasonal trends, two
 major effects were evident.  The mid-lake central  basin and to a lesser
 extent the north and south shoreline exhibited an  early spring maximum,
 a summer minimum and  a  rapid  increase following fall turnover.   The
 western  basin  and  Sandusky sub-basin both had highest average  concen-
 trations  during  the  summer months and lower concentrations in  both
 spring and fall. The  percent of  the yearly total  chlorophyll a and  pheo-
 pigment  present during each cruise substantiates  these western and
 central  basin trends (Tables 54 and  55).   Contour maps of corrected
 chlorophyll a concentrations averaged for all depths from  each cruise
 of  1973 through  1975  further depict seasonal trends  (Figures 64-78).
 Volume-weighted cruise tonnages  and concentrations of corrected chloro-
 phyll  a_ and pheopigment a are  presented  for the central  (Table 56) and
 western  (Table  57) basins.

      The  factors responsible for the seasonal responses  of the  phyto-
 plankton  are complex.   Seasonal  variations  in temperature and light
 are of primary significance  in the development of phytoplankton  standing
 crop.  As the  vernal  equinox approaches,  the sun moves directly over-
 head resulting  in a  greater percent of the sun's  light penetrating the
 water column.    This provides more  available light  for photosynthesis
 while increasing the  water temperature.   During the late spring  and
 summer  months low turbidity in the  western and central basins further
 enhances  light  penetration.   The  shallow western  basin warms more
 rapidly than the deeper central basin and  maintains a higher temperature
throughout the  summer.   These conditions plus  the  availability of nutrients


                                   186

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00
                                                                      CORRECTED CHLOROPHYLL a (JJG/L)
                                                                        STATION MEANS FOR 1973-1975
                                                                       CONTOUR INTERVAL = 5 pG/L
                  Figure  63.  Corrected  chlorophyll  a (xjg/l)  station means  for 1973-1975.

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          TABLE  54.   PERCENT OF ANNUAL TOTAL  CORRECTED CHLOROPHYLL  a AND
         PHEOPIGMENT a CONTRIBUTED AT EACH CRUISE INTERVAL -  CENTRAL  BASIN
Yoar Llmnlon
1973 epl
me so
hypo
total
1974 epl
meso
hypo
total
1979 ept
meso
hypo
total
Unstratified
Apr 1 1 -May
Chi a







13.9



14.4
Pheo a







13.0



26.4
Stratified
June
Chi a




5.9
0.7
3.0
9.6
3.6
0.7
3.3
7.6
Pheo a




4.3
0.6
3.6
8.5
3.0
0.7
3.0
6.7
July
Chi a
12.6
1.5
3.6
17.7
8.2
0.2
1.2
9.6
4.4
1.1
3.2
8.7
Pheo a
19.8
2.3
3.3
25.4
9.4
0.4
2.7
12.5
2.2
0.6
1.9
4.7
Aug- Sept
Chi a
20.8
1.8
3.0
25.6
12.6
0.9
1.6
15.1
17.3
1.0
3.5
21.8
Pheo a
24.1
3.6
3.8
31.5
10.1
0.9
3.5
14.5
9.5
0.7
3.0
13.2
Sept-Oct
Cht a




13.3
0.5
1.1
14.9



28.2
Pheo a




23.9
0.9
2.7
27.5



13.3
Unstratified
Oct-Dec
Chi a



56.7



36.8



19.2
Pheo a



43.1



23.6



35.7
CO
CO

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          TABLE 55.   PERCENT OF ANNUAL TOTAL CORRECTED  CHLOROPHYLL a AND
          PHEOPIGMENT a CONTRIBUTED AT EACH CRUISE INTERVAL - WESTERN  BASIN
Year Llmnlon
1973
ept
meso
hypo
total
1974
epl
meso
hypo
total
1975
epl
meso
hypo
total
April-May
Chi a









11.1




12.7
Pneo a









8.0




18.3
June
Chi a









12.7




25.8
Pneo a









10.7




16.6
July
Chi a I




26.7




20.8




21.4
Pheo a




43.6




24.8




11.6
Aug-Sept
Chi a




37.2




21.2




19.8
Pheo a




25.1




22.6




18.8
Sept-Oct
Chi a









16.6




14.8
Pheo a









24.2




20.5
Oct-Dec
Chi a




36.1




17.5




5.5
Pheo a




31.3




9.8




14.1
00

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                                                  ! CORRECTED CHLOROPHYLL a (JJG/U
                                                      AVERAGE FOR ALL DEPTHS
                                                            SAMPLED
                                                    CRUISE 2  JULV 17-JULV 24, 1973
                                                    CONTOUR INTERVAL = ?-10
Figure 64.  Corrected chlorophyll  a (jjg/\~) average  for all  depths sampled,
             cruise 2,  July 17-July 24, 1973.

-------
                                               CORRECTED CHLOROPHYLL a (JJG/U
                                                AVERAGE FOR ALL DEPTHS
                                                       SAMPLED
                                               CRUISE 5 AUG. 29-SEPT. 4, 1973
                                               CONTOUR INTERVAL » 2-1O JLK3/L
Figure 65.
Corrected chlorophyll  a (Mg/l)  average  for all  depths
sampled, cruise 5, August 29-September  4, 1973.

-------
ro
                                  CORRECTED CHLOROPHYLL a (LIG/U
                                    AVERAGE FOR ALL DEPTHS
                                          SAMPLED
                                  CRUISE 7  OCT. 14-OCT. 24, 1973
                                  CONTOUR  INTERVAL = 2-10 JJG/L
                     Figure  66.
Corrected chlorophyll a  (;ug/l) average For  all depths
sampled, cruise 7, October 14-October  24, 1973.

-------
UD
CO
                                               CORRECTED CHLOROPHYLL a (JJG/L)
                                                                        AVERAGE FOR ALL DEPTHS
                                                                               SAMPLED
                                                                    , CRUISE 2  APR. 25-MAY 4, 1974
                                                                    j CONTOUR INTERVAL = 2-5  XJG/L
Figure 67.
                                   Corrected  chlorophyll a (ug/l) average for all depths
                                   sampled,  cruise 2,  April 25-May 4, 1974.

-------
vo
                                                                     CORRECTED CHLOROPHYLL a (JJG/L)
                                                                      AVERAGE FOR ALL DEPTHS
                                                                              SAMPLED
                                                                     CRUISE 4  JUNE 1-JUNE 10, 1974
                                                                     CONTOUR  INTERVAL = 2-5 JUG/L
                                                                     		 !	I	j	
Figure  68.
                                  Corrected chlorophyll  a (jug/I) average  for all  depths
                                   sampled,  cruise 4,  June  1-June  10,  1974.

-------
in
                                                                    CORRECTED CHLOROPHYLL a (JJG/U
                                      AVERAGE FOR ALL DEPTHS
                                           SAMPLED
                                  ,  CRUISE 5  JUNE 28-JULY 7, 1974
                                  1  CONTOUR INTERVAL = 2-10
                    Figure 69.
Corrected chlorophyll  a Oug/l) average for  all depths
sampled, cruise 5, June 28-July  7,  1974.

-------
vo
                                                                    CORRECTED CHLOROPHYLL a (JJG/L)
                                                                     AVERAGE FOR ALL DEPTHS
                                                                            SAMPLED
                                                                    CRUISE 7 AUG. 12-AUG. 19, 1974
                                                                    CONTOUR INTERVAL * 2-10 L'G/L
Figure 70.
                                Corrected chlorophyll a C/ug/l) average for all depths
                                sampled, cruise 7, August 12-August 19,  1974.

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10
                                                                           CHLOROPHYLL
                                                                     AVERAGE FOR ALL DEPTHS
                                                                           SAMPLED
                                                                   CRUISE 8  AUG. 26-SEPT. 7, 1974
                                                                   CONTOUR  INTERVAL =2=10 JJG/L
                   Figure 71.
Corrected chlorophyll a (jug/I)  average for all depths
sampled, cruise 8,  August 26-September 7,  1974.

-------
00
CORRECTED CHLOROPHYLL a (JJG/U
                                                                      AVERAGE FOR ALL DEPTHS
                                                                             SAMPLED
                                                                    CRUISE 10 OCT. 21-NOV.  1, 1974
                                                                    CONTOUR INTERVAL = 2-5 JUG/L
                    Figure 72.  Corrected chlorophyll  a (;ug/l)  average  for  all depths
                                  sampled,  cruise  10,  October 21-November  1,  1974.

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10
                                                                    CORRECTED CHLOROPHYLL a UJG/L)
                                                                   1.0 METERS BELOW LAKE SURFACE
                                                                   CRUISE 1A & 1B MARCH 27-APR. 2E
                                                                               1975
                                                                     CONTOUR  INTERVAL = 2-5 JJG/L
                     Figure 73.   Corrected chlorophyll a (jug/I), cruise 1A  and 1B,
                                   March 27-Aprll 25,  1975.

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t\>
o
o
                                                                       CORRECTED CHLOROPHYLL a (JJG/L)


                                                                      1.0 METERS BELOW LAKE SURFACE

                                                                       CRUISE 2 JUNE 9-JUNE. 19, 1975

                                                                     I  CONTOUR INTERVAL = 2-10 JJG/i,
                           Figure 74.  Corrected chlorophyll  a (jug/I), cruise 2,

                                        June 9-June 19,  1975.

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ro
o
                                                                       CORRECTED CHLOROPHYLL a (JJG/L)
                                                                      1.0 METERS BELOW LAKE SURFACE
                                                                       CRUISE 3 JULY 13-JULY 21, 1975
                                                                        CONTOUR INTERVAL = 2-10 JUG/L
                           Figure 75.   Corrected chlorophyll a (AJg/l),  cruise 3,
                                         July 13-July 21,  1975.

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ro
o
                                                                     CORRECTED CHLOROPHYLL a (JUG/L)
                                                                    |1 .0 METERS BELOW LAKE SURFACE

                                                                    ' CRUISE 4  AUG. 30-SEPT. 5, 1975

                                                                     CONTOUR INTERVAL = 2-5 1JG/L
                          Figure 76.   Corrected  chlorophyll a  (xjg/l),  cruise 4,

                                        August 30-September 5, 1975.

-------
ro
o
CO
                           CORRECTED CHLOROPHYLL a (JJG/L)


                           1.0 METERS BELOW LAKE SURFACE

                            CRUISE 5  SEPT.  27-OCT. 6, 1975

                            CONTOUR INTERVAL = 2-5
                            Figure 77.
Corrected chlorophyll  a Qug/l),  cruise  5,

September 27-October 6,  1975.

-------
ro
o
-P.
CORRECTED CHLOROPHYLL a (LJG/L)
                                                                    1.0 METERS BELOW LAKE SURFACE

                                                                     CRUISE 6  DEC. 2-DEC. 14. 1975


                                                                     CONTOUR INTERVAL = 2 JJG/L
                          Figure 78.   Corrected chlorophyll a (ug/l), cruise 6,

                                       December 2-December 14,  1975.

-------
TABLE 56.   CORRECTED CHLOROPHYLL- a AND
      PHEOPIGMENT a  - CENTRAL BASIN
Limnion
1973
Epi tons
M9/1
Meso tons
M9/1
Hypo tons
M9/1
Total tons
M9/1
1974
Epi tons
(J9/1
Meso tons
M9/1
Hypo tons
M9/1
Total tons
M9/1
1975
Epi tons
M9/1
Meso tons
pg/1
Hypo tons
M9/1
Total tons
M9/1
Unstratified
April-May
Chi a










1082.73
3.47







1571 .02
5.09






Pheo a










231 .82
0.79







584 . 20
1 .89






Stratified
June
Chi a










458.06
2.34
58.29
2.56
233.22
2.49
749 . 57
2.40

395 . 1 1
2.27
81 .48
2.65
362.84
3.47
839.43
2.71
Pheo a










78.05
0.40
11 .05
0.49
65.54
0.70
154.64
0.50

66.90
0.38
14.78
0.48
67.18
0.64
148.86
0.48
July
Chi a

535 . 1 8
2.34
63.97
2.86
152.21
2.48
751 .36
2.40

641.82
2.58
18.28
1.46
92.21
1 .84
752.31
2.41

482.69
2.64
121 .26
3.41
351 .75
3.89
955 . 70
3.10
Pheo a

248.53
1 .08
28.90
1 .29
41 .21
0.67
318.64
1 .02

1 68 . 82
0.68
6.34
0.51
48.73
0.79
223 . 89
0.72

49. 08
O.27
13.96
0.39
41 .41
0.46
104.45
0.34
                                                  (continued)
                         205

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TABLE 56  (continued)
Limnion
1973
Epi tons
M9/1
Meso tons
M9/1
Hypo tons
M9/1
Total tons
M9/1
1974
Epi tons
M9/1
Meso tons
M9/1
Hypo tons
M9/1
Total tons
M9/1
1975
Epi tons
M9/1
Meso tons
pg/i
Hypo tons
jjg/l
Total tons
M9/1
Stratified
Aug-Sept
Chi a

884 . 99
3.72
75.90
3.05
1 29 . 40
2.75
1 090 . 29
3.52

985.20
4.19
72.81
3.05
127.02
2.51
1 1 85 . 03
3.82

1894.42
8.33
108.98
7.16
380.98
5.77
2384.38
7.72
Pheo a

302.90
1 .27
45.64
1.84
48.07
1.02
389 . 61
1 .26

181 .01
0.77
17.01
0.71
63.18
1.25
261 .20
0.84

210.04
0.92
14.80
0.97
66.06
1.00
290.90
0.94
Unstratified
Sept-Oct
Chi a










1036.03
4.26
41.61
2.38
85.16
1.76
1 1 62 . 80
3.76

3086.02
10.05






Pheo a










429.46
1.77
17.05
0.98
49.02
1 .01
495 . 53
1.60

293 . 58
0.96






Oct-Dec
Chi a

2409 . 1 2
7.87







2871.40
9.45







2103.32
6.92






Pheo a

541.78
1.77







423.44
1 .39







790.16
2.60






           206

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TABLE 57.   CORRECTED CHLOROPHYLL a AND
 PHEOPIGMENT a - WESTERN  BASIN,  1973-1975
Limnion
1973
Epi tons
M9/1
Meso
Hypo
Total
1974
Epi tons
H9/1
Meso
Hypo
Total
1975
Epi tons
H9/1
Meso
Hypo
Total
1973
Epi tons
jjg/1
Meso
Hypo
Total
1974
Epi tons
pg/l
Meso
Hypo
Total
1975
Epi tons
M9/1
Meso
Hypo
Total
Chi a Pheo a
April-May


210.OO 26.17
8 . 75 1 . 09

244.52 66.01
1 0 . 34 2 . 79

Aug-Sept
277.61 81.74
11.74 3.46


403.22 73.83
17.14 3.14


380 . 86 67 ..99
16.31 2.91

Chi a Pheo a
June


241.74 34.81
10.03 1.44

495.14 6O.36
21.07 2.57

Sept-Oct



316.09 78.60
13.48 3.35


284.58 74.21
12.34 3.22

Chi a Pheo a
July
199.28 141.82
8.34 5.93

395. O9 80.78
16.50 3.37

410.76 42.19
17.59 1.81

Oct-Dec
269.37 101.77
11.99 4.52


331.43 31.70
14.65 1 .40


105.01 51.23
4 . 66 2 . 27

                        207

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 in the western  basin  provide  an environment favorable for algal growth
 evidenced  by the  high concentrations of chlorophyll a_ observed  throughout
 the basin during the summer.

      The  central basin maintained  high chlorophyll a concentrations in
 the spring prior to stratification and during the  fall "following turnover.
 The maximum central basin concentrations were found in the fall just
 after turnover when the nutrient-rich hypolimnion  became mixed with
 the nutrient-depleted  epilimnion.  In the late  fall,  storms  cause resus-
 pension of sedimented material, which increases the turbidity.   At the
 same time,  water temperatures are decreasing, and, thus,  chlorophyll
 concentrations decline during  this period.

 Year to Year Trends
      In order to facilitate a year to year comparison of chlorophyll a
in Lake Erie, volume-weighted quantities (metric tons) were  calculated.
The cruise by cruise volume-weighted  quantities were plotted for 1973
through  1975,  and points  equidistant between the cruises were used to
estimate chlorophyll a. values for periods between  cruises.   The between-
cruise estimates  and the  cruise  values  were averaged for  each year to
give estimated chlorophyll a tonnages for the western  and  central basins.
This procedure was used  to  compensate for  irregular  sampling intervals
and varying  number of cruises over the three-year period.  For  compar-
ative  purposes only, the between-cruise estimates  of chlorophyll a from
June through November of each year were used due  to the great vari-
ability found in early spring and late fall data.

      From  1973  to  1975, the mean tonnage  of corrected chlorophyll a
increased  in the central basin:                                       ~"

                             Central Basin
                    1973              1201.25 tons
                    1974              1291 .78 tons
                    1975              1795.08 tons

From  1973  to  1975,  an increase of 49 percent was estimated and the
greatest year to year difference,  a 38 percent increase  in corrected
chlorophyll  a_,  occurred between 1974 and  1975.   This large increase was
attributed to a greater hypolimnion concentration  of chlorophyll a in 1975
than in 1974.  The  establishment of the thermocline higher in the  water
column in  1975 resulted  in a  larger hypolimnion volume.  Since a great-
er portion of the  hypolimnion was  in the photic  zone and nutrients were
less likely to become limiting,  the hypolimnion  was able to support a
larger standing crop of phytoplankton during  this  year.   In  addition, the
extensive anoxic conditions which developed in the hypolimnion in 1973

                                   208

-------
and 1974 were not encountered in 1975.  Lack of extensive anoxia also
provided a more favorable hypolimnion environment than  was previously
observed.

      From 1973 to 1975 the mean tonnage of corrected chlorophyll a
increased in the western basin, with the greatest increase in  mean tons
occurring between 1973 and 1974.  The three-year data is as follows:

                            Western Basin
                    1973               236.96 tons
                    1974               342.51 tons
                    1975               395.01 tons

The corrected chlorophyll a. tonnages  were estimated to be 44.5  percent
greater in 1974 than 1973, and  a further  increase of 15 percent  was
calculated  for 1975 and 1974.

      The  significance  of year to year differences of chlorophyll  a ton-
nage  in Lake Erie is somewhat difficult to evaluate over a short time
period.  Yearly  changes in  standing crop  can be expected due to sea-
sonal variation,  different  meteorological effects and cruise scheduling.
Only  a  sampling  program spanning several additional years  will provide
the necessary information to evaluate changes in the trophic status of
the lake.

Historical  Trends
      Few previous studies  on Lake Erie  have examined  chlorophyll
concentrations (Table 58).   Tucker (1949) utilized  1939 western basin
chlorophyll data supplied by Chandler and Weeks and  reported  a good
correlation (r = 0.78) between phytoplankton counts and plankton pig-
ments using the technique developed by Harvey (1934).   Brydges (1971)
reported  western basin and  north shore data collected between 1967 and
1969.   Spectrophotometric determinations were made on pigments ex-
tracted in 90 percent acetone and concentrations were calculated using
the equations developed by Richards and Thompson (1952).  Brydges
found chlorophyll a to be positively correlated with total phosphorus,
with the highest concentrations of both chlorophyll  a_ and total phosphorus
found in the western  portion of the lake.   Only two entire Lake  Erie
chlorophyll surveys have been undertaken, one by the Federal  Water
Pollution Control Administration (FWPCA, 1968) in May, July  and  Octo-
ber of  1967 and January and  August of 1968,  and another by Glooschenko
et al. (1974) based on 10 cruises from April to  December of 1970.
                                   209

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TABLE 58.   SIMILAR STATIONS FROM CHLOROPHYLL
  SURVEYS UNDERTAKEN BY THE FEDERAL WATER
   POLLUTION  CONTROL AGENCY (1968) AND THE
     CENTER FOR LAKE ERIE AREA RESEARCH
                      1974-1975
                STATION NUMBERS

  FWPCA.  1967 - 1968       CLEAR, 1974 - 1975

         D9-1                      81

         E2-1                       70

         G12-1                      50

         D13-1                      51

         F16-1                      47

         H20-1                      73

         L3O-1                      78

         L36-1                      79
                          210

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      The FWPCA  sampled 30  stations along a longitudinal transect of
the entire lake (Figure  79).  Eight  FWPCA stations are  comparable  to
CLEAR western  and  central  basin stations (Table 58)  and were  used for
comparison.  The  original FWPCA  data utilized  Richards and Thompson's
equations (1952), and the data  was  reported as chlorophylls a plus b.
The raw data absorbencies were obtained  and recalculated using the
SCOR/UNESCO chlorophyll  a equation (1966).  The averages  (surface
and  mid-depths)  for  the  eight stations  on  each of the  May,  July and
October  cruises  were recalculated and plotted (Figure 80).  The FWPCA
1967 May to October average chlorophyll  a was  estimated to be 4.86
pg/1.  Cruise averages based  on the  eight similar CLEAR stations dur-
ing  corresponding  time  periods were  plotted (Figure 80).  The  CLEAR
data  for 1973 have not  been  included  in this analysis  because of missing
data  prior to July.  The yearly SCOR/UNESCO  chlorophyll a averages
for  1974 and 1975  were 9.24 ,ug/I  respectively.   The 1974 and  1975
chlorophyll  a concentrations  were higher  than the 1967 averages which
may be only"partially attributed to  differences in sampling schedules.
There was  an increase  of 7.08 jug A of chlorophyll a  from 1967  to 1975
for  the western  and  central  basins  representing  an  increase of  146 per-
cent.

      Problems were encountered in utilizing  the 1967 FWPCA  data.
The original FWPCA 645 nm absorbences (chlorophyll b_) were  found to
be as high  or higher than the  absorbences  at 663 nm (chlorophyll  a).
Absorbences for chlorophyll b should be  consistently  lower than chloro-
phyll a absorbences.  It has been pointed out that the Beckman D
spectre-photometer used  by the FWPCA may have been miscalibrated
(Cornelius  Weber, U.S.  EPA, Cincinnati,  personal communication).
Thus, the FWPCA chlorophyll data lost much of its validity.

      Glooschenko, Moore and Vollenweider (1974) sampled 5 western
basin and 12 central basin  stations during  10 cruises  in  197O.   Samples
were collected  at  1  m  and  5 m depths and integrated.   The analytical
procedures  were similar to  those used by CLEAR, 1973 through 1975,
making the  data comparable.   Five western basin and twelve central
basin CLEAR  stations similar  in location to Glooschenko were  selected
for comparison  (Figure 81  and Table  59).  Basin averages were cal-
culated using only surface and mid-depth or lower  epilimnion values
 for comparison  with the 1970  study.   Only SCOR/UNESCO chlorophyll  a
values were compared  since the  1970 report  did not  include corrected
chlorophyll  a.   Yearly averages were calculated for  1970 and  1973
through 1975~ based  on  cruises from  June to November (Tables 60 and
 61).
                                   211

-------
                                                    1967-1968  F\APCA
                                                    STATION LOCA1 ION
Figure 79.  FWPCA station locations,  1967-1968.

-------
           14 -
r\>
i—i
CO
           10 -
        O)
         BJI
a
2
o
6
                            1975^
            6 -
                          ^-  11.94 jug/I,  1975
                               (June to  November)
                               mean

                               9.24 jug/I, 1974
                               (June to  November)
                               mean
                                                                              4.86 jug/l, 1967
                                                                              (May  to October)
                                                                              mean
1967
                Figure 80.
                    Comparison of central and  western basin chlorophyll a values
                    (average of surface  and  mid-depth values) from the FWPCA,
                    1967 data and corresponding 1974  and 1975 data.

-------
r>o
                                                                         CLEAR  STATIONS
                                                                     ENCLOSED IN BOXES USED
                                                                     FOR  COMPARISONS WITH"  '
                                                                       GLOOSCHENKO'S  1970
                                                                       CHLOROPHYLL STUDY
                         KILOMETERS
                        0        '0
                        STATUTE MILES
          Figure 81.
                                                                                                 79"
CLEAR stations  enclosed in boxes used for comparisons with
Glooschenko's  1970 chlorophyll study.

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  TABLE 59.  SIMILAR STATIONS FROM CHLOROPHYLL
SURVEYS IN GLOOSCHENKO (1970) AND CLEAR  (1973-1975)
    Glooschenko,  1970           CLEAR, 1973 - 1975
    Station Number              Station Number	

    Western Basin               Western Basin
           23                         50
           25                         61
           27                         59
           29                         55
           31                         53

    Central  Basin               Central Basin
           7                         79
           9                         31
           14                         37
           18                         44
           22                         46
           34                         40
           35                         42
           37                         35
           38                         78
           41                         29
           44                         26
           47                         25
                             215

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  TABLE 60.  AVERAGE CHLOROPHYLL a (ug/l) IN  LAKE ERIE
  1970 BY MONTH AND  WESTERN TO CENTRAL BASIN RATIOS
Cruise
April 7-11
May 6-10
June 2-6
July 3-7
July 28 - August 1
August 25 - 29
September 23 - 27
October 21-25
November 25 - 30
December 14 - 18
April 1 - December
(Yearly Average)
June-November Average
Western
5.9
4.4
5.9
11 .9
9.8
19.3
10.2
7.8
7.6
3.3
8.9
10. 8
Central
5.3
2.9
2.7
2.5
3.7
4.1
9.2
3.0
5.4
5.7
4.4
4.2
W
1 .11
1 .52
2.19
4.76
2.65
4.71
1 .11
2.60
1.41
0.58
2.02
2.58
: C
: 1 .0
: 1 .0
: 1 .0
: 1 .0
: 1 .0
: 1.0
: 1.0
: 1.0
: 1.0
: 1.0
: 1 .0
: 1 .0

Data source:
  Taken from  Glooschenko et al.,  1974 (Eastern Basin data deleted).
                               216

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TABLE 61 .   CLEAR SCOR/UNESCO CHLOROPHYLL a
CONCENTRATIONS  BASED ON  STATIONS SIMILAR TO
   GLOOSCHENKO'S 1970 SURVEY (SURFACE AND
                MID-VALUES  ONLY)
Year
1974











1975











Cruise
1
2
3
4
5
6
Yearly
Average
(n = 6)
June-Nov
Average
(n = 5)
1
2
3
4
5
6
Yearly
Average
(n = 6)
June-Nov
Average
(n = 4)
Western
5.36
7.47
15.16
15.19
11 .09
12.05

11 .05


12.34

13.27
14.10
12.05
15.87
10.74
8.28

12.39


13.19

Central
4.68
2.30
1 .94
3.63
5.13
8.73

4.40


4.35

6.20
1 .82
2.85
8.20
10.34
8.82

6.37


5.80

Basin
W
1.15
3.25
7.81
4.18
2.16
1 .38

2.51


2.84

2.14
7.75
4.23
1 .94
1 .04
0.94

1 .95


2.27

Ratio
C
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00

1 .00


: 1 .00

1 .00
1.00
1 .00
1 .00
1 .00
1 .00

1 .00


: 1.00

                         217

-------
      The central basin chlorophyll a_ trends for 1970,  1974  and 1975
 were similar (Figure 82).  The bimodal peaks  occurred during the spring
 and early fall,  and a summer minimum was evident all three years.
 The magnitude  of the high and  low values  found each year were similar,
 with differences due to cruise scheduling and fluctuations in the standing
 crop.   The greatest increase in the average June  to  November chloro-
 phyll a concentration occurred  between 1974 (4.35 ;ug/l) and 1975 (5.80
;ug/l).   The  central  basin showed an estimated  concentration  increase
 of  38 percent from 1970 to 1975.

      The western basin chlorophyll  a.  concentrations  were high through-
 out the summer months all three years  (Figure 83).   The average  June
 to  November  chlorophyll a_ concentration was lowest in 1970 (10.82 jug/l),
 while in  1975 the average  was  13.19/jg/l.  This represented an esti-
 mated  increase of 2.37 jug/1 or 22  percent from 1970  to 1975.

      If all CLEAR western and central  basin stations and all depths •
 were utilized for comparison  with Glooschenko's 1970  study,  the increase
 is even greater (Table 62).  The 1975 June to  November western basin
 chlorophyll a average would be  18.26 jjg/l, representing a 7.44 jjg/l
or  84 percent estimated  increase in the  western basin chlorophyll  a con-
centration from 1970 to 1975.   An estimated increase of 2.04 jug/l~or
46  percent was calculated for the central basin from  1970 to 1975 based
on  this  comparative  technique.   This large increase can be partially
attributed to a more intensive lake coverage in 1974 and 1975 particular-
ly along the  shorelines of the central basin and a  more  thorough coverage
of the western basin.  The observed increase can  be attributed to sevei—
al factors such as year to year fluctuations, meteorological  influences
and continued enrichment  of the lake.  The factors most responsible
for the  observed increase can best be  determined  from continued yearly
studies.   Comparisons of chlorophyll a data taken  from  several investi-
gations  are difficult to evaluate  because  of differing analytical techniques,
sampling  schedules  and sampling  locations (Tables 58  and 59).  There-
fore, trends based on such  comparisons must be viewed conservatively.

Trophic Status
      Various trophic classification  systems have been proposed  based on
chlorophyll  a concentrations.   Three such  classification systems were
examined to evaluate the degree of  eutrophication of Lake  Erie.   Gloos-
chenko and  Dobson (1975) established eutrophication classifications based
on chlorophyll a_ data from the  Great Lakes.  Tailing (1961) devised a
classification system applicable to marine  Investigations.   Sakamoto
(1966) studied a  series  of Japanese lakes ranging from 4.5 to  65 m in
depth from  which he developed  a  method for determination of trophic
status.   The three classifications were as  follows:

                                   218

-------
   10 •
   6 -•
 ol
 jj 4
 5
    2-
     1975 f
                    1970
5.80 pg/l=1975 mean

   X*


  :4.35 ;jg/l=1974 mean
  4.20 jug/t=1970 mean
       J  rF  '  M  ' A  ' M '  J  ' J  '  A ' S  '  O  n  N  '  D '
                                Month
Figure 82.
 Comparison of central basin  chlorophyll a^ values
 from Glooschenko's 1970  data and  corresponding
 1974  and 1975 data.
    20  1
     16  -
     12
  ral
  .c
  a
  o
  L
  O
                 12.34 xjg/l=1974 rr.ean	/__:
                 10.82 ,ug/1=1 970 mean	/_/\J	T	!-•_.__
                                           13.19 >ug/l=1975
                                           mean
Figure 83.
'F'M'A'M'J'J'A'S'O'N'D'
                  Month
 Comparison of  western  basin chlorophyll a values
 from Glooschenko's  1970  data and  corresponding
 1974  and 1975 data.
                                219

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TABLE 62.   CLEAR  SCOR/UNESCO CHLOROPHYLL a
     VOLUME WEIGHTED CONCENTRATIONS.  BASIN
   VALUES  INCLUDE ALL STATIONS AT ALL DEPTHS
Year
1973




1974











1975











Cruise
1
2
3
Yearly
Average
1
2
3
4
5
6
Yearly
Average
(n = 6)
June-Nov.
Average
(n = 5)
1
2
3
4
5
6
Yearly
Average
(n = 6)
June-Nov.
Averages
(n = 4)
Western
10.42
13.70
16.15

13.42
9.78
10.93
18.24
18.84
15.45
14.46


14.62


15.58
11 .92
22.53
18.14
18.09
14.26
6.O3


15.16


18.26
Central
2.93
3.91
8.97

5.27
3.85
2.80
2.73
4.34
4.70
10.33


4.79


4.98
6.19
2.95
3.26
8.23
10.53
8.21


6.56


6.24
Basin
W :
3.56
3.50
1 .80

2.55
2.54
3.90
6.68
4.34
3.29
1 .40


3.05 :


3.13
1.93
7.64
5.56
2.20
1 .35
0.73


2.31 :


2.93 :
Ratio
C
1 .00
1 .00
1 .OO

1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00


1 .00


1 .00
1 .00
1 .00
1 .00
1 .00
1 .00
1 .00


1 .00


1 .00
                            220

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                                                           Glooschenko
                            Sakamoto        Tailing        and Dobson

          Eutrophic         5-140 jug/I       30 >ug/l       5-10 ;ug/l
          Mesotrophic       1-15  ;ug/l     1-30 jug/I          5 jug/I
          Oligotrophic    0.3-2.5  >ug/l        1 jug/I

      The yearly average volume-weighted  corrected  chlorophyll a^  concen-
trations for each sub-basin were used  to evaluate the three classification
systems.   When Glooschenko  and  Dobson's system was  applied, the west-
ern basin, Sandusky sub-basin and  western central  basin were found to
be eutrophic,  while the eastern central basin was judged  mesotrophic.
According  to  Sakamoto's  classifications the western  basin and  Sandusky
sub-basin were eutrophic and the  entire central basin was considered
mesotrophic.   With the criteria developed  by Tailing, both the western
basin and central basin were  considered mesotrophic.

      Of the types  of investigations  used to establish each of the classi-
fication systems,  the  Glooschenko-Dobson  system, developed from  using
Great Lakes data,  seems to be the most applicable to Lake  Erie.

Particulate Organic Carbon versus Chlorophyll a
      During the last  cruise  of  1973  and all cruises  in  1974  and 1975,
calculations and  tonnages of  particulate organic carbon  (POC) were
determined at all stations  sampled.  The western basin concentrations
(Figure 84) and tonnages (Figure  85) of POC and  corrected chlorophyll
a both demonstrated an increase during the summer months  and a de-
c~rease  in the fall.  In the central basin both  chlorophyll a_ and POC
decreased  from the spring phytoplankton pulse through mid-summer and
increased  in the late  summer and early  fall.   During the December
cruise of 1975 an  inverse  chlorophyll a - POC relationship was evident
in the central basin.   It was felt that  as  a result of the high winds
occurring  in the late  fall,  detrital POC was resuspended from the sedi-
ments.   During this period,  chlorophyll  a^ concentrations decreased due
to the suboptimal conditions  for phytoplankton growth.   Central basin
surface and bottom area-weighted concentrations of particulate phos-
phorus  (PP),  POC and corrected  chlorophyll a_ were examined (Figures
86 and  87).  It was apparent especially in the surface waters  that de-
creases and increases in chlorophyll a were accompanied by corres-
ponding changes  in PP and POC until December (Cruise 6).

      Ratios of pheopigment to corrected chlorophyll a,  corrected chloro-
phyll  a to  POC and PP to POC were used to  examine the  effect of  resus-
pension on  chlorophyll a concentrations (Figures 88 and 89).   The spring
                                   221

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l\5
ro
ro
                      1500
                      1000
                    o
                       500
                                     LEGEND


                               » -Western Basin POC


                               •-Western Basin Chi a


                               x-Central Basin Chi a


                               *—Central Basin POC
                                                     |4 15  |7|8
                                                                               |2 |3   |4 |5    |6
                            J'J'A'S'O'N'D|J 'F 'M'A'M'J 'j 'A'S 'o 'N ' D I j ' F MA M j j 'A 's 'o 'N '6T

                                 1973                 1974                      1975
2O
                                                                                                15
                                                                                                10
                   Figure  84.   Particulate organic  carbon and  corrected chlorophyll  a

                                  concentrations -  Lake Erie  central  and western basins,

                                  1973-1975.

-------
ro
PO
co
                       200  -
                       150  -
                       100 -
                     p
LEGEND  * Western Basin POC


        * Western Basin Chi a


          Central Basin Chi a

        » Central Basin PCC
                     o
                     0
                     Q.
                               'A 's 'o ' N ID JJ 'F i MI AIM' j ' j ' A1 s ]o 'N 'c | j >F 'WA 'M'J ' j 'A is 'O ' N'D

                               1973                 1974                      1975
                                                                                             4000
                                                                                             3OOO
                                     20OO   O



                                          IB
                                     1000   2


                                           o
                                           z
                     Figure 85.  Particulate organic  carbon and corrected  chlorophyll  a

                                   tonnages,  Lake Erie central and western  basins,  1973-

                                   1975.

-------
IN3
                        01
                        Z  0-
                        o  Q.
                       12
 i- 24


  22


 - 20


   18



 - 16


   14



 - 12



   10



 - 8


   6



21- 4
                            r600
                            -500
                            U400
                            -300
                            -200
                            - 100
                                    . POC
                                    pp

                                     \
                                    Chla
    _  „, CRUISE |l	

       MAR  I  APR  I  MAY
                                                                   |4	la
                                                           	

                                                  JUN  j  JUL  |  AUG  |  SEP  |  OCT    NOV     DEC
                     Figure  86.  Lake Erie central basin surface water  - 1975:   corrected

                                  chlorophyll  a, partlculate  phosphorus and  partlculate or-

                                  ganic carbon concentrations, area weighted.

-------
ro
ro
                       2  0.   O
                              O.
                       O  O.
I2p24






IOJ-20



   18
                       8
                           -600
                        - 16
                          14
                        - 12
                           -500h    pp
                                   x
                                    N.
                           -400
                          10-
                        - 8
                        - 4
                        L 0
                           -300
    -200
                           h- 100
                                    POC
                                    Chlo
                               CRUISE  I
       -|%.nwTjt. [I              [^       [3


       MAR  I  APR  |  MAY  |   JUN  (   JUL
      |4	 |S     	 !*

"AUGI  SEPI  OCT|NOV|DEC
                    Figure 87.   Lake Erie central  basin bottom water -  1975:  corrected

                                  chlorophyll  a, participate  phosphorus  and particulate  or-

                                  ganic carbon  concentrations, area weighted.

-------
•0.5
    0.4
   0.3
   0.2
   O.I
               Ratios of:   Pheophytin vs. Corrected Chlorophyll a
                         Corrected Chlorophyll a vs. Particulate" Organic Carbon
                         Particulate  Phosphorus vs.  Particulate Organic Carbon
                         (Area Weighted)
       CRUISE
                                                                          -10.05
                                                                               0.05
                                                                               0.03
                                                                               0.02
                                                                          POC_
                              -li
                                    li.
        MAR  I  APR  '  MAY '   JUN'JUL '  AUG  '  SEP  '  OCT '   NOV
                                                                      DEC
                                                                              0.01
     Figure 88.   Lake Erie  central  basin  bottom water -  1975.
o
<
    0.5
   0.4
   0.3
   0.2
   O.I
               Ratios of:  Pheophytin vs.  Corrected Chlorophyll a
                         Corrected Chlorophyll a vs.  Particulate Organic Carbon
                         Particulate Phosphrous vs.  Particulate  Organic Carbon   005
                         (Area Weighted!
       CRUISE   11
                           _LL
                                                                               0.04
                                                                               0.03
                                                                              0.02
                                                                              0.01
        MAR  i  APR  I  MAY  '   JUN  '   JUL  '  AUG  '' SEP  '' OCT  '  NOV  '

     Figure 89.   Lake  Erie  central  basin surface  water  -  1975
                                      226

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and fall were periods of the highest pheopigment to corrected  chlorophyll
a ratios,  indicative of a resuspension of detritus containing  pheopigment.
During the same periods, the PP to POC ratio was  also  high.   It was
assumed the PP as well as POC was resuspended from the  sediments;
however,  the large quantities of PP were not necessarily of an  organic
nature.  The chlorophyll a  to POC  ratio was low during the fall due to
the decrease  in chlorophyll  a and an increase  in  POC.  The highest
chlorophyll  a to POC ratio  occurred during the late  summer and cor-
responds  to "to the highest standing  crop in the central basin.   During
this same period,  the pheopigment  to corrected  chlorophyll a  ratio was
the lowest, indicative of a larger portion of the chlorophyll  a  associated
with viable cells.   It was evident that the correlation between corrected
chlorophyll a and POC, and to  a less degree PP, was quite strong
during the sTratified period, but not during unstratified periods.  This
poor correlation was attributed  to  resuspension of previously settled
plankters which had undergone various degrees of decomposition.  The
increase  of pheopigments and POC  strengthens this conclusion.   It is
also possible that  chlorophyll a not  associated with viable cells  is re-
suspended.   If this occurs, the biomass estimates based  on chlorophyll
a and  POC may be misleading during periods  of extensive resuspension.

Summary and Conclusions

      1.   As a segment of  the  Lake Erie nutrient study  1973, 1974
          and  1975, corrected chlorophyll  and pheopigment  concen-
          trations  were determined at  51  stations  in  the western
          and central basins.   Of the 2,332 corrected chlorophyll a
          measurements taken,  98  percent  of the values ranged  be-
          tween 0.34 and 29.12 jug/I.  The mean of these observa-
          tions was 7.50 /ug/l.

      2.   The spectrophotometric technique recommended by SCOR/
          UNESCO (1966) was utilized for the analytical procedure.
          Concentrations of chlorophylls a, b_ and  £ were calculated
          according to  SCOR/UNESCO along  with corrected chloro-
          phyll a^  pheopigment  a^ and the Fo/Fa ratio described  by
          Lorenzen (1967).   Only corrected chlorophyll a and  pheo-
          pigment  £* were discussed in detail.

      3.   The quantitative effects of basin, station,  cruise,  sampling
          depth and stratification have been determined with analysis
          of variance models.  Of  these variables,  basin was con-
          sidered  a first order effect, while station  within basin and
          cruise had second order  effects.
                                    227

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 4.  The  seasonal trends of chlorophyll a differed in the
     western and central basins.  Due to  different physical,
     chemical and biological  factors influencing these two
     basins,  they exhibit different seasonal patterns.  The
     western basin maintained highest chlorophyll a  con-
     centrations during the summer months,  while~the cen-
     tral  basin exhibited  two peaks, one in the early spring
     and the  other following turnover  in the late summer
     (early fall).

 5.  The  June to November mean concentration of corrected
     chlorophyll a was shown to  increase yearly from 1973 to
     1975.  The  maximum  increase in tons for the central
     basin was 38 percent, which occurred in 1975,  while the
     maximum  increase for the  western basin of 44  percent
     was observed in  1974.

 6.  Long-term  chlorophyll trends are difficult to evaluate.
     Lake Erie chlorophyll  surveys have been undertaken
     by the Federal  Water  Pollution Control Administration
     (FWPCA,  1968)  in 1967  and 1968 and by  Glooschenko
     in  1970 (Glooschenko,  et al.  1974).   The FWPCA
     survey  substantiated the year to year chlorophyll  in-
     creases  observed in the 1970's.   The increase  in
     chlorophyll a concentration  over the nine-year  period
     (June to November  1967 to  1975)  was 7.08 ug/l or
     146 percent.  Due to an apparent  analytical problem
     the FWPCA  data  was of questionable  reliability.  When
     Glooschenko's 1970 survey was compared with the cor-
     responding CLEAR survey  a 38 percent increase in the
     central  basin chlorophyll a  concentrations was estimated
     between 1970 and 1975.  Thirty-three percent of the in-
     crease occurred between 1974 and 1975.  The western
     basin showed an estimated 22 percent  increase  between
     1970  and  1975,  with the  greatest  Increase observed  from
     1974  to 1975.

7.   The western basin and the western half of the central
     basin were  considered  eutrophic based on criteria of
     the chlorophyll trophic classification system established
     by  Glooschenko  and Dobson  (1975).  The eastern half
     of the central basin was considered mesotrophic.
                             228

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     8.  The relationships of participate organic carbon to
         chlorophyll a and pheopigment to  chlorophyll a
         were examined during 1975, in order to evaluate
         the effects of  resuspension.  Particulate organic
         carbon and pheopigments  were found to increase
         during  periods of maximum resuspension,  while
         chlorophyll concentrations decreased.  This would
         indicate that during the spring and  fall  periods of
         high winds,  detrital  material is  resuspended con-
         tributing to the particulate  organic  carbon and
         pheopigments  in the  water  column.

     9.  The drawbacks involved  in  the chlorophyll technique
         have been discussed throughout the text.   Errors
         involved in the analytical portion of the technique
         have been calculated.   Measurement errors are
         negligible, and error due to extended periods  of
         storage present the greatest analytical error.
         Determination of chlorophyll concentrations from
         samples freeze stored for  more than two  months
         may yield concentrations that underestimate the
         actual  values.

         In  calculating  volume-weighted tons of chlorophyll
         it was assumed that the  horizontal  distribution of
         chlorophyll was consistent  within a grid.    Patchi-
         ness of phytoplankton does  occur, thereby  resulting
         in  patchy  chlorophyll concentrations.  Error in
         chlorophyll analysis as a result of patchiness  seems
         inevitable  but  has not been quantified.

                            REFERENCES

Brydges, T.G.   1971.  Chlorophyll a Total phosphorus  relationships in
    Lake  Erie.  Proc.  14th Conf. Great  Lakes.  Res.   185-190.

Federal Water Pollution Control Administration.   1968.    Lake Erie Sur-
    veillance data summary 1967-1968.   U.S. Dept.  Interior.  65 p.

Glooschenko,  W.A.  and H.F.H.  Dobson.   1975.   Water  quality in the
    Great  Lakes.   Nature Canada.   4:3-6.
                                  229

-------
 Glooschenko, W.A., J.E. Moore and R.A. Vollenweider.  1974.   Spa-
     tial and temporal  distribution of chlorophyll  a and pheopigments in
     surface waters of Lake  Erie.   J.  Fish. ResT Bd. Can.  31:265-274.

 Harvey, H.W.   1934.   Measurement of phytoplankton population.  Mar-
     ine Biology  Assoc. U.K.  19:761-773.

 International Joint Commission.  Great Lakes Water Quality  Board.
     1975.   Great Lakes water quality, 1974 annual  report, appendix B.

 Lorenzen,  C.J.   1967.  Determination of chlorophyll and pheo-pigments
     spectrophotom etr ic equations.   Limnol.  Oceanogr. 12:343-346.

 Odum,  H.T.,  W. McConnell and W. Abott.  1958.   The chlorophyll a
     of  communities.   Publ.  Inst. Mar. Sci. Texas  5:65-96.       ~

 Richards,  F.A.  and T.G. Thompson.  1952.   The  estimation and chai—
     acterization of  plankton  populations by analyses II:  a spectrophoto-
     metric method  for the estimation of  plankton pigments.   J. Mar.
     Res.   11:156-172.

 Sakamoto,  M.   1966.   Primary  production  by phytoplankton community
     in  some Japanese  lakes  and  it's dependence on  lake depth.  Arch.
     Hydrobiol.   62:1-28.

 SCOR/UNESCO.  1966.   Monograph on oceanographic methodology  I.
     Determination of photosynthetic  pigments in  sea water.   Paris. 69  p,

 Strickland, J.D.H.  and T.R. Parsons.   1968.   A practical  handbook of
     seawater analysis.  Fish.  Res. Bd.  of Can. Bull.  167  p.

 Tailing, J.F.  1961.   Photosynthesis under natural  conditions.  Ann.
     Rev. Plant Physiol.  12:133-154.

 Thomas, R.L.,  J.-M.  Jaquet and A.L.W. Kemp,   1976.   Surficial
     sediments  of Lake Erie.  J. Fish. Res. Bd.  Can.  33:385-403.

Tucker, A.  1949.  Pigment extraction as a method of quantitative
     analysis of phytoplankton.  Amer.  Micros.  Soc. Trans.   68:21-33.

Verber, J.L.  1950.   Percent and area of contour levels  of  Lake Erie.
     mimeo.  4 p.

Vollenweider, R.A.   1971.   Scientific  fundamentals of the eutrophication
     of lakes and flowing waters,  with particular reference to nitrogen
     and  phosphorous as factors in eutrophication.   Organization  Econom.
     Coop.  Develop.   Paris.   159 p.
                                  230

-------
                              SECTION 8

       PRIMARY  PRODUCTIVITY SURVEY OF THE  CENTRAL
              AND WESTERN BASINS OF LAKE ERIE

                         Clifford T.  Sheffield
                Center for Lake Erie Area Research
                      The  Ohio  State University

                           Walter E. Carey
                  Department of Nuclear Engineering
                      The Ohio State University
INTRODUCTION

     Within the last twenty years biologists have  observed that man has
increased the nutrient  input of Lake  Erie to cause significant changes in
its  flora and fauna (Beeton and  Edmondson 1972).  From  1938-1964, to-
tal  phytoplankton concentration in the island area  increased by 3.5 times,
and the dominant  phytoplankton changed from diatoms to blue-green algae.
From  1920-1962 in  central Lake Erie,  phytoplankton numbers  increased
several fold  during  spring and autumn pulses.

      Primary productivity is a measure of the rate of buildup of organ-
ic compounds from  the energy that  is  transferred to successive trophic
levels.  Ths  photosynthetic process  is  responsible for the greater part
of this buildup in most environments (Goldman 1963).  Estimates of pri-
mary  productivity for  Lake Erie first  appeared in 1949,  when Verduin
(1951) measured the rates of CO2  removal per unit of phytoplankton
volume per hour  in western  Lake Erie.  Verduin concentrated  phyto-
plankton by passing lake water  through bolting cloth and  placed these sam-
ples in bottles under an optimal light  intensity of 4OO  foot candles (fc).
However,  he  estimated that  about two-thirds of the photosynthetic organ-
isms escaped concentration (Verduin 1956).  Consequently,  since  1957 he
has used natural  phytoplankton densities and has estimated  rates of Co2
removal in open-lake conditions.   He  found that  under these conditions
photosynthetic rates exceed those rates obtained  from  bottle experiments
by  two times (Verduin  1960  and 1962).  For these  reasons his more
recently published rates of 3070 mg absorbed  per m   per day for net

                                   231

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 photosynthesis and 616O mg C absorbed per m2 per day  for gross  photo-
 synthesis are used for comparison to the  results of subsequent studies,.

       Saunders (1964) made the  first estimates of primary productivity
 in Lake  Erie  with  14c at a. single  station in the  western basin in 1957;
 estimates were  68.3 mg  C/m3 per day for  net and 142.9 mg  C/m3 per
 day for gross photosynthesis.   He  converted these  estimates to 97.6
 and 371.5 mg C/m   per  day,  respectively,  for net and gross daily
 integral  photosynthesis by using  a formula derived  by Rodhe,  Vollen-
 weider and Nauwerck (Saunders  1964).

       Further  primary productivity work was done on  Lake  Erie  in 1968
 when  Porkso et al.  (1969) took a one-day cruise  along the entire lake
 to  make  the first  estimates of primary productivity for central Lake
 Erie.   With the 14C  technique and  a shipboard incubator  (light intensity
 = 1000 foot candles,  temperature = 60°F), Parkos  et al.  (1969) found
 surface rates  of 127.7 mg  C/m3 per hour at one station  in the western
 basin  and 42.4-54.7  mg C/rr>3 per  hour at two stations in the central
 basin.   In 1969  and 1970, Cody  (1972) used  14C and  found extremely
 variable  rates, from 11-5470 mg-atoms C [132-65,640 mg C]  per m2
 per day, in  western  Lake Erie during m situ studies at ten stations.
 Glooschenko et al.  (1974) made  intensive measurements in Lake Ontario
 and all three basins of Lake Erie (25 stations) by calibrating a ship-
 board  incubator (light intensity = 8000 lux, temperature = surface water
 temperature)  with  simultaneous in situ experiments.   Surface water
 productivity obtained  from the  incubator for  each  station was converted
 to an  in  situ  estimate for the entire water  column.  Mean values for
 ten cruises in 1970 were  30-4760 mg C/m2  per day and 120-1690 mg
 C/m   per day for  the western and central basins respectively.

     This report includes data for  the  central and  western basins of
 Lake Erie that were  obtained during July-October 1974.   The  objectives
 of the  study  were to  investigate,  by means of the 14c method  and ship-
 board  incubation of samples, the  vertical,  horizontal  and  temporal  dis-
 tribution  of primary productivity in central and western Lake Erie  and
 to compare data obtained  in  1974 with data from previous  investigations.
 Samples  were  taken from five  western basin stations  and eleven central
 basin stations  during  cruises abourd the R/V Hydra—-26 July-6 August
 (Cruise 6), 12 August-19  August  (Cruise 7),  26 August-7  September
(Cruise 8), and 21 October-1 November (Cruise 10, Figure 90).

     Between  cruises,  a  location approximately 250 m offshore,  south
of The  Rattles of Rattlesnake Island  in western  Lake  Erie  was chosen
for in  situ experiments.  Cody (1972) reported  ranges of 16.7-185.4
                                  232

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CO
CO
                                            R - .11. of jg glU productivity eKp.rlm.nt.
                                                  near Rattlesnake Icland
                Detroit
                                                    [Cleveland
                       Figure 90.   Map  of Lake  Erie  showing  station locations  in  the central

                                     and western  basins.

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mg-atoms  C [200-2225 mg C] per  m3  per hour, 36.1 -  654.9 mg-atoms
C  [433-7859 mg  C] per m2 per hour,  and 240-5470 mg-atoms C [288O-
65,640 mg  C] per m2  per day for optimal, integral,  and daily  integral
primary  productivity, respectively, at Rattlesnake Island in  1970.

PROCEDURES

Field Methods

      At  each station submarine photometer readings were taken at one-
meter intervals  from lake surface to bottom, or  until the light meter
read zero.   The  reading  made  when the photometer was suspended just
above the water  represented surface light intensity.   Samples of lake
water were collected  from one  meter  and from a depth  of about one  per-
cent of the surface light  intensity, which represented the lower limit
of the euphotic zone.   Samples were also collected  from intermediate
levels (commonly three meters and five meters), depending  upon  the
thickness of the  euphotic  zone.

      Sample  preparation  follows the method of Goldman  (1963).  A sam-
ple of lake water, taken  with a five-liter  Niskin  sampling bottle,  was
transferred to 300-ml BOD bottles,  two light and one dark for each
depth.   The dark bottles  were wrapped with a double layer  of black
electrical plastic tape.  A layer of aluminum foil covered the tape to
prevent  heat buildup.  Two layers of foil  covered the stopper to  keep
out light.   Between cruises both dark and light bottles  were  washed
with concentrated HNOg and  thoroughly rinsed with  tap  water with a
final  rinse  of distilled water.   The bottles were  inverted and air  dried.

      A  fresh stock solution of 14C was  prepared daily  by combining  the
contents  of ampules of sodium bicarbonate -  14C (NaH14CO3) in sterile
aqueous  solution with pH  = 9.5,  which was supplied in  the amount  of
5.0 pd/5.0 ml per ampule by  New  England Nuclear  Corp.   Approxi-
mately  1.0 ml of the stock solution was  added  to each BOD  bottle by
means of a 2-ml hypodermic  syringe (accuracy = + 5 percent)  with
a  15-cm 18-gauge needle.  The stock  solution was  added to  the bottom
of the bottle, and the syringe was rinsed gently with water from  the
top of the  bottle.  The activity of the  NaH14COs, added via  the syringe,
was taken  to  be  1.0 jjd  (2.22 x 106 + 10 percent disintegrations per
minute)  as  determined by New England Nuclear Corporation.

     After  innoculation,  the bottle contents were thoroughly mixed,  and
the bottles  were placed in a shipboard incubator for three to five  hours.
Light intensity of approximately 9OOO lux was provided  by a  bank of six
                                 234

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daytime  fluorescent lamps.  Surface  water was  continuously circulated
through the incubator.  After incubation the bottle contents were mixed,
10 ml of material was removed  with  a repipet,  and 10 ml merthiolate
solution  was added to stop further 14C uptake.  The  bottle contents were
thoroughly mixed.

      Since the relative  activity  of the plankton  was unknown when  exper-
iments were begun,  the  investigator concentrated as  much material as
possible from  a bottle onto a membrane filter.   As more material  is
added, sample  counting time decreases linearly, unless the additional
material decreases detection of  the   -particles emitted from 14C.   In
areas with high concentrations of  suspended particles,  filter  pores
clogged within approximately ten minutes.  In some areas (e.g.,  Sta-
tions 30, 47, and 73), the entire  bottle content  was passed through the
filter within ten minutes; in other areas (notably Stations 61, 75,  and
76) aliquot was used  since the filtration time  for the entire content
would have exceeded  ten  minutes.  Material from each BOD  bottle was
vacuum-filtered onto  a 25-mm diameter Gelman  GA-6 Metricel  membrane
filter (pore size  0.45 u).  The  filtration apparatus aboard the R/V Hydra
consisted of a vacuum manifold  that held four filter funnels so that the
contents of as many as  four BOD bottles could  be  filtered simultaneously.
Vacuum  pressure did not exceed 300 mm  Hg.   Since the membrane fil-
ters  differ  in  rates  of water  absorption,  all filters were  presoaked in
distilled water  to decrease filtration  time.  Once the material had been
concentrated on the  membrane filter,  the  filter  was rinsed with approxi-
mately  25 ml  of  0.003  N HCl  to remove any  14C that may have accumu-
lated on the surface of the filtered material;  a  rinse of 25 ml filtered
lake  water (if available) or distilled water followed.   The membrane
filter was then attached  with  household glue to a 32-mm diameter  stain-
less  steel planchet.   Water  retained  by the filtered material absorbs
the   -particles emitted from  14C, so filters were  stored in  pillboxes
and  assayed several  weeks later.

Radioassay

      Filters were assayed with a thin end-window gas-flow detector;
gas  composition  was approximately O.9 percent  isobutane in  99.1  pei—
cent  helium.   Planchets were loaded onto a Nuclear  Chicago Corp.
Model No.  C-110B automatic sample changer.  A  Nuclear Chicago
Corp. Model 181A sealer recorded the counts per  measurement,  and
a Nuclear Chicago Corp.  Model No.  C.111B printing timer recorded
the time required for the measurement.   A 0.0875 AJCI14C standard
                                    235

-------
source  was used  to calculate counter yield by the formula of Arena
(1971):
                               Y =  cpm/dpm,

where Y  is counter yield, cpm is  observed count rate of the standard
(counts per minute), and  dpm  is the calibrated activity of the standard
(disintegrations per minute).   Counter yield was  16-17  percent.   Light
bottles  were counted a  minimum of 10,000 counts (+2.1  percent pro-
bable error at P  = 0.05) and dark  bottles a minimum of 1OOO counts (+
(+6.4  percent probable error at  P = 0.05).   One thousand counts  per"
measurement for  dark  bottles  was chosen to  reduce sample  counting
time  to about ten minutes.   The discrepancy between light and dark
bottle counting statistics  is discussed later.
Primary Productivity Calculation

      Incubator productivity was  calculated by an expanded formula
developed by  Saunders,  et  al. (1962).   Dark bottle incubator proauc-
tivity was subtracted  from  light  bottle incubator productivity to correct
for nonphotosynthetic  uptake of 14C.  The corrected incubator produc-
tivity (mg C/m • h) was  converted  to  integral productivity (mg C/m2. h)
by the relationship  reported by Glooschenko et  al.  (1974):

                            mg C/m2th  _
                            mg C/m3.h  =  1-85x>

where mg C/m2.h  is integral  productivity,  mg  C/m3.h is incubator
productivity,  and  x is Secchi disc depth in meters; the relationship is
solved for mg C/m2*h.   Since the incubator productivity of Glooschenko
et al. (1974)  is based on a composite sample from one-meter and  five
meter depths, incubator productivities from one-meter and  five-meter
depths in this report  were  averaged,  and the mean value was  inserted
into  the  above relationship.  Integral  productivity was converted to daily
integral  productivity (mg  C/m2« day) by the method  of Glooschenko  et
al.  (1974).

In situ Productivity

      Procedure for in situ productivity experiments near Rattlesnake
Island was similar  to the shipboard method except  incubation.   Photo-
meter readings and Secchi disc  depth were determined as previously
described.  Temperature was  measured  by means of a YSI Model  51A
dissolved oxygen meter equipped with a YSI 5450 probe.   Lake water
                                  236

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was  collected with a three-liter  non-metallic  Kemmerer water sampling
bottle.   For the one-meter depth,  one intermediate depth, and the  bot-
tom  sampling depth, pH was measured  in the laboratory on  South Bass
Island within two hours of collection, and total  alkalinity  was determined
within four hours of collection.   Upon  innoculation with one microcurie
of NaH14CO~,  one light and one  dark bottle were suspended  in  the lake
at the depth  from which the water was  taken.   The incubation appara-
tus consisted of an  anchored nylon  line with an attached float on  the
lake surface.  Aluminum strips  were tied to  the  line at the  proper
depths.  The BOD bottles  were attached to the  strips  by  shower  cui—
tain  hooks that  fastened to  hose  clamps at the necks of the bottles.   If
possible, the samples  were fixed when  the  bottles were  retrieved from
the line; when the weather  was  rough, they were fixed at the laboratory
approximately half an  hour after retrieval.   Samples were  filtered at
the South Bass Island  laboratory or aboard the R/V Hydra,  and the
membrane filters were prepared for gas-flow counting.

      ln_ situ  primary productivity (mg  C/m3- h)  at each sample  depth
was  calculated.   These estimates were then plotted against depth on
graph paper.   Integral in  situ  productivity (mg  C/m • h)  was calculated
by determining  the  area beneath  the productivity-depth curve with a
planimeter.
Correction  Factors
      The filtered material absorbs energy from the 3 -particles  emitted
from 14C and  prevents the  escape and subsequent detection of some of
the particles by counting  equipment.   Lower sample count rate and,
therefore, lower  productivity result.   An experiment was  performed to
determine whether this self-absorption of 3-particles occurred in fil-
tered material  during  the 1974  season.  Lake  water from  a depth of
one  meter in Put-in-Bay  Harbor was collected  with a  Kemmerer water
sampling bottle on 5 October 1974.  The water was transferred  to  six
clear BOD bottles,  and approximately  one microcurie  of NaH14CO3 was
was  added to each bottle.   After  the contents were thoroughly mixed,  the
the bottles were  incubated approximatly  four hours in  the  shipboard
incubator.  After incubation the contents were fixed as previously des-
cribed.  Aliquots of 25, 50,  75,  and 100 ml  from  each bottle were
filtered  onto membrane filters  as  described.   Because filtration of the
100-ml aliquots required  approximately ten minutes, these volumes
were assumed to represent the denser concentrations  of material
collected over the season.   Filters were rinsed and processed for  gas-
flow counting as  in the productivity experiments.    Filters  were  counted
10,000  counts  minimum.   Sample count rate  was corrected to actual
                                  237

-------
  C uptake.  Carbon-fourteen  uptake  (dpm) was divided by aliquot
volume (ml) and duration of incubation (h),  and the  result (dpm/ml
per hour)  was plotted against  aliquot volume.

      Strickland and Parsons (1968) stated that the fixative formalde-
hyde at a  concentration of 0.3 percent volume may influence the
excretion or loss of fixed  14C from the  more  delicate  marine algae.
The effect of merthiolate upon sample activity was  studied, as  mer-
thiolate  may also  cause  14C loss from  phytoplankton.  Lake water
collected  on 16 September from one meter below the surface of
Put-in-Bay Harbor  was added  to six clear 300-ml BOD bottles.
About one  microcurie  NaH14CO>3 was added and th° bottles were
incubated approximately four hours in the  shipboard  incubator.
Samples were fixed as in the  productivity experiments.  At  intervals
of  1, 2, 4,  8,  16,  and 24 hours after- fixation 5O-ml ali.quots  from
each BOD  bottle were filtered  onto membrane  filters.   The filters
were prepared for  gas-flow counting.  The experiment  was run again
on  19 October 1974, and aliquots  were filtered at intervals of 0, 1,
2,  4,  8, and 16 hours after fixation.  During  both  experiments bot-
tles were  stored overnight and filtered the next day.   Filters were
counted 10,OOO counts  minimum.   Graphs were drawn of carbon-fourteen
uptake per ml  per hour vs. time after fixation for the twelve bottles.

      Relative light  intensity  in the incubator was  measured while
the research vessel was docked at Put-in-Bay on 19 September 1974.
The incubator  was  divided into nine horizontal  zones, and several
photometer readings were taken at each  zone to represent light in-
tinsity at clear water, mid-lake central  basin  stations, as the water
had been standing for  several  days.   Photometer readings were re-
peated after the water had been circulated for two  hours,  which
approximated turbid stations.  Whether or not relative light intensity
was reduced by use of a clear plexiglass top when the lake was
rough was also determined.  A mean relative  light intensity value
for any position in  the incubator during each set  of conditions was
determined by averaging individual measurements at each location
in the incubator.
                                  238

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RESULTS AND  DISCUSSION

      Incubator,  integral,  and daily integral productivity in 1974
were, respectively, 4.1-124 mg C/m3 per hour,  16-364 mg C/m2
per hour,  and 140-4370 mg C/m2  per day for western Lake Erie
and 5.1-51.2 mg C/m3 per hour,  44-242 mg C/m2 per hour,
and 53O-2180 mg C/m2 per day for central Lake  Erie (Table 63).
Results of calculations using  Glooschenko's relationship are present-
ed in Table  64.

      Maximum incubator  productivity in 1974 agrees  to within 3
percent of that reported by Parkos et al. (1969) and  16 percent of
the maximum mean productivity per cruise reported by Vollenweider
et al. (1974) for western  Lake  Erie (Table 63).   Maximum central
basin incubator productivity in  1974 is 2.4 times  greater  than the
mean productivity per  cruise  reported by Vollenweider, but the dif-
ference may be  in the comparison of  mean values per cruise to a
range of values  for the entire season of 1974.  Parkos et al. (1969)
report productivity 7  percent  greater  than the  maximum incubator
productivity  found during this study.

      Daily integral   productivity reported by Saunders (1964) is
relatively low when compared with other  western basin estimates
in Table 63,  but  this probably is explained by his  sampling one  site
late  in the year. The lower  limit of Verduin's estimates fall with-
in the daily  integral  productivity  range calculated  in 1974.  Cody's
(1972) mean  estimate of 10,OOO mg C/m2 per day is  2.3  times
greater  than the maximum daily  integral   productivity in the west-
ern basin in  1974.

      Central Lake Erie incubator  productivity for late  July averaged
1.7 times  mid-August values  and 0.7 times  late October  values
(Table 65).   Nutrient release  upon fall overturn (Gachter et al.  1974)
probably resulted in the October maximum.   Mean incubator produc-
tivity for western Lake Erie  decreased from late July to late October
with  the July value being  1.4 and  1.6 times  greater than September
and October  values respectively. Integral productivity  for central Lake
Erie followed, the trend of incubator productivity with the late July value
being 1.2 times  the August value and 0.9 times the October value.
Western Lake Erie integral productivity in July was 2.4 and 1.7
times September and October integral productivity, respectively.
                                   239

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          TABLE 63.   COMPARISON OF  PRIMARY PRODUCTIVITY MEASUREMENTS IN
                      CENTRAL AND  WESTERN LAKE  ERIE FROM 1957-1974
Date

1957-1962

1957 Oct.

1968 July

1969-1970

1970 Api — Dec.


1974 July-Oct.


1968 July

1970 Apr-Dec.


1974 July-Oct.
Method

pH-CO2
4 A
14C
14
C
14
14C
14
C

14
C
4 A
14C

14C
14
C

•\ A
14C
Incubation

natural conditions

In situ

shipboard

_ln situ

[_n_ situ, shipboard


In sttu
shipboard

shipboard

^n_ situ, shipboard


shipboard
mg C/m3.h mg C/m .h
Western basin




127.7

13.2-2225 18.0-7859

4 . 8- 1 46 . 9a 5 . 0-397a


3.6-152 95-342
4.1-124b 16-364,
Central basin
42.4-54.7

5.5-21.4a 17-141a


5.1-51.26 44-242
mg C/m .day

net 3,070
gross 6, 16O
net 96.7
gross 371 .5


132-65,640
mean 10,OOO
30-4, 760a



140-4,370



1 20-1 , 69Oa


530-2,180
Source

Verduln (1962)

Saunders (1964)

Parkos, Olson &
Odlaug (1969)
Cody (1972)

Vollenwelder, Muns
war & Stadelmann
(1974)
Sheffield (1975)


Parkos, Olson &
Odlaug (1969)
Vollenwelder,
Munawar, & Stadel-
man (1974)
Sheffield (1975)
a    range of mean values per cruise

b    range of station means for productivity within cuphotlc zone

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   TABLE 64.  CARBON ASSIMILATION RATES  BY STATION
AND CRUISE  FOR CENTRAL AND WESTERN LAKE ERIE IN 1974
Mean Incubator Rate3 Integral Rate Daily Integral Rate
Date Station

1 Aug 30
30 July 47
4 Aug 48
27 July 52
26 July 6l
28 July 66
27 July 67
30 July 73
26 July 75
26 July 76

13 Aug 23
13 Aug 25C
14 Aug 30
15 Aug 34C
15 Aug 3^
17 Aug 44
12 Aug 47
16 Aug 48

6 Sept 53
7 Sept 6l
6 Sept 67
7 Sept 75
7 Sept 76

23 Oct 23
23 Oct 25
26 Oct 30
26 Oct 32
27 Oct 36
27 Oct 39
29 Oct 44
21 Oct 47
28 Oct 48
30 Oct 53
1 Nov 6l
29 Oct 66
30 Oct 67
21 Oct 73
l NOV 75
31 Oct 76
a average of all sample
b incubator rates from
found in Glooschenko
c includes sample from
d includes sample from
(ng C/m^.h + SE)
Cruise 6
19.8 + 1.5
16.4 7 1.6
11.1 7 1.2
20.8 7 3.3
12.4 7 1.3
33.0 7 3.1
33.5 + 1.4
17.3 + 2.2
124 7 6
98 7 2
Cruise 7
8.3 + 0.9
5.1 7 0.4
8.1 7 0.9
10.1 7 1.0
7.271.3
13.6 + 0.8
14.0 7 0.7
15.7 7 0.9
Cruise 8
33.3 + 2.2
30.4 + 1.1
31.0 7 1.6
32.3 7 2.3
76.8 + 2.6
Cruise 10
23.1 + 0.9
14.5 + 0.5
18.4 7 1.1
10.9 7 0.6
18.6 7 1.0
17.0 ~ 1.2
51.27 1.2
29.9 7 1.6
23.2 7 0.9
34.8 7 0.9
4.1 + 0.1
28.1 7 1.0
46.0 7 1.4
30.371.7
77.6 + 2.4
26.4+ 1.2
depths.
1 m and 5 m depths were averaged
et al (1974)
metalimnion.
hypolimnion.
2
(mg C/m .h)

130
180
83
109
37
194
157
133
364
166

94
84
84
82
73
124
154
135

44
87
75
57
85

87
82
80
69
160
60
242
216
172
123
16
136
141
223
171
73

and the mean



2
(mg C/m .day)

1560
2160
1000
1310
440
2330
1880
1600
4370
1990

1130
1010
1010
980
880
1490
1850
1620

530
1040
900
680
1020

780
740
720
620
1440
540
2180
1940
1550
1110
140
1220
1270
2010
1540
660

value inserted into the relationship.



                              241

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                TABLE 65.  MEAN  PRODUCTIVITY BY BASIN  FROM JULY-OCTOBER 1974
No. of
Stations
Cruise 6
5
5
Cruise 7
8
Cruise 8
4
Cruise 10
11
5
Basin
central
western
central
western
central
western
Incubator
Productivity
(mg C/m3.h + SE)
17.1 + 1 .7
60 +22
10.2 + 1 .3
42.6 + 11 .4
24.7 + 3.4
36.4 +12.3
Integral
Productivity
(mg C/m2 .h)
127
184
104
76
138
107
Daily
Integral
Productivity
(mg C/m2. day)
1530
2200
1250
910
1240
96O
ro
-fa.
ro

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    Horizontal distribution of incubator productivity follows that  of
previous investigators.   Parkos et al. (1969) and Glooschenko et  al.
(1974) report a west to east gradient in  Lake Erie  with  the  highest
productivity  in the western  end.   A  north to south gradient in both
basins during 1970 (Glooschenko et  al.  1974) is not quite as evident
during 1974.  The maximum  productivity in mid-summer in western
Lake Erie reported by Glooschenko occurred in 1974.   However,
upon  examination of his  monthly distribution maps (Glooschenko
et al. 1974, Figure95),  one finds that the estimates of 124  mg
C/m3- h  reported in  July 1974 for Stations  75 and 76 are  nearly
double those reported for the summer 1970.

      Results of  three in situ experiments near Rattlesnake Island
show that when productivity"^ mg C/nrP-h) is plotted against relative
light  intensity,  three distinct curves result  (Figure 91>   Primary
productivity  on 10 September remained linear through a relative
light  intensity at least 2.5  times greater then that for  21 July and
6 October.   In October, when surface light  intensity and water
temperatures are lower,  phytoplankton survive at lower light  inten-
sities than  in July and September.   Primary productivity in October
leveled  off more rapidly than in July and  September.

      For each of the three  in situ  experiments the primary produc-
tivity vs. depth  curve has a  slope similar to its  corresponding
light  transmission curve (Figure 92>   Maximum  productivity  occur-
red at approximately one meter.   Cody  (1972) reported  maximal
productivity in western Lake Erie from  one to three  meters and
rarely at depths  shallower  than one meter.

      For a  series of increasing volumes of filtered phytoplankton,
self-absorption of 3-particles from  14C  exists if a decrease in
dpm/ml per hour occurs.  Results of the self-absorption  experiment
(Figure 93) indicate that there was no decrease in dpm/ml per hour,
although results from individual bottles  varied.   No correction of
sample count rate was made on the basis of  this  evidence.

      Effect  of merthiolate  fixation  on sample activity  experiments
indicate that loss of activity occurs non-linearly  for approximately
the first eight hours (Figure 94>   Approximately  14 percent loss
occurs during the first  four  hours,  another five  to seven percent
during e§ht additional hours.   On the average, approximately 21
                                   243

-------
   200
   160
o
|120
o
I  80
   40
o  21 July 1974
•  10 Sept 1974
A   6 Oct  1974
                                  10
                                 15
20
25
30
                                    Relative Light  Intensity   (juA x 10 )
                  Figure 91.   Relationship of in  situ  productivity to relative light
                               intensity near  Rattlesnake Island.

-------
ro
-t=.
tn
                                              % Surface Light Intensity
                                                                      10
                                                       light transmission
                         A 21 July

                         o 10 Sept

                         •  6 Oct
                     0.1




                     Figure 92.
            1.0                      10

        Relative  lin Situ Productivity


Relationship  of relative  in situ  productivity and light

transmission of  depth near  Rattlesnake Island.
100

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              20
              18
              14
             I
              12
                           ERROR BARS REPRESENT ±SE
                          25         50         75
                               Aliquot Volume (ml)
                                                           100
  Figure 93.   Relationship of sample activity to  aliquot volume.
                               ERROR BARS REPRESENT ± SD
                                      12       16       20
                                      Time After Rxation (h)
Figure  94.   Relationship  of sample activity  to time after  fixation.
                                     246

-------
percent of the original  activity is  lost per sample within eight hours
after fixation.  Again individual bottles vary  in  loss  rates.   Hourly
loss rates become similar  after eight hours.

     Relative incubator  light intensity in clear water averaged
900 y A (range of 775-1075  yA) and 775 ~v A (range of 675-975  yA) in
turbid water.  When the clear plexiglass  top  covered the top of the
incubator during rough  weather, relative  light intensity  in clear
water  was reduced  from  900 to  825 y A (range of 725-925 yA), a
reduction of 9 percent.   Since no records were kept  of the horizon-
tal  position of the bottles in the incubator,  no correction was applied
to the carbon assimilation  rates.

     The estimated average range  of total error of a single produc-
tivity  measurement determined by the methodology presented  in
this report is +18 percent to -32 percent.  Counting statistics,
syringe calibration,  ampule activity calibration  and  fixation effects
were factors considered.   Dark bottle 14C uptake and light bottle
14C uptake can both be expressed in relative units in which light
bottle  uptake equals 100 and  dark bottle uptake  its corresponding
percentage.   From such  consideration the relative dark uptake
(49 percent) that yields the greatest uncertainty to the net sample
count  rate contributes a total  probable  error in counting statistics
of 10  percent (P =  0.05).  Mean relative  dark bottle  uptake of
14  percent (n =  182) yields a probable  error of 3 percent (P = 0.05),
and  thus the  mean  probable error caused  by counting statistics
alone  is +3 percent.   Syringe accuracy contributed+5 percent error.
Accuracy of ampule calibration  by  New England Nuclear Corp.  as
determined by ampule lables and technical  information  is assumed
to be  +10  percent of the  stated  value of 5.0  yCi per  5.O ml
[1.0 PCi/1.0 ml]  aqueous solution.  Samples were assumed to have
been filtered within four  hours after fixation.  Therefore,  samples
lost 14 percent of their original activity  (Figure 94, curve  B).  This
estimate is probably conservative since filtration  of  some  samples
was not completed  for  at least 24 hours.   No accurate records
were kept  of the time between sample fixation and filtration,  as the
fixation effect was  not  discovered until about two-thirds of  the samples
had been taken through the sampling season.  For this reason primary
productivity  measurements remain uncorrected for sample activity
loss.   The fixation effect contributes the greatest uncertainty to the
methodology used during  this  study.
                                  247

-------
    Agreement  between duplicate light bottles (n = 183 pairs) av-
 eraged 21 percent +2 percent (SE)  for all samples over the entire
 season.   This measured value, falls  within the predicted range of
 + 18 percent to  -32 percent.  Saunders et al. (1962) reported that
 +20 percent is  the normally accepted  error  for  estimates  of photo-
 synthesis.  The positive side of the estimated error for 1974 is
 10 percent less than  Saunders' figure, while the negative  side  is
 60 percent greater,  since sample fixation  causes loss in addition to
 the three other sources of  error considered.  The amount of error
 introduced by the relationship  of Glooschenko et al. (1974) is un-
 known.  Error bars in figures accompanying the text represent the
 estimated  error of +18 percent to  -32 percent unless otherwise
 indicated.

      Graphs of the vertical  distribution of incubator productivity
 within the euphotic zone reveal that the wide range of error may
 reduce productivity maxima  and minima of raw data.  For example,
 the graph  of incubator productivity  vs. depth for Station 47 on
 30 July (Figure 95) shows that  peaks at 1  m,  5 m,  and  14  m reduce
 to a small  increase  (approximately  20 percent) from 1  m  to  a
 plateau at about 7 m.   Superficially,  a doubling of incubator pro-^
 ducttvity  is observed from 2 m to  5 m and from  7 m to  14 m.
 Vertical profiles where maximum productivity was  £ 1 .32  times the
 minimum productivity were compared.  Maximum  to mintmum  pro-
 ductivity ratios _> 1.32 were considered significant, since  -32 per-
 cent was  the average maximum error  involved in making the
 productivity estimates.   The number of significant  productivity
 profiles was 15 of 39 or  38 percent of the total  incubator  produc -
tivity experiments.

     Central Lake Erie incubator productivity  profiles had  a wider
 range  of carbon fixation rates  than  western Lake Erie profiles.
Maximum productivity to  minimum  productivity ratios for central
 Lake Erie averaged  1.80, 1.83, and 1.17  for  early August, mid-
August, and late October, respectively.  SAfestern Lake  Erie ratios
averaged  1.33,  1.16, and 1.07  for  late July, early September, and
late October, respectively.   For central  Lake Erie at  Station  23
during both mid-August and late October maximum  productivity at
 1  m decreases  with depth (Figure 95>  The profile  at Station 25 in
mid-August showed increasing  productivity from  about 5  m to a
plateau at  15 m to the bottom  of the euphotic zone at 18 m (Figure
                                  248

-------
^10
a
0)
D
  15
  20
              10
20
    Incubator Productivity (mg C/m3-h)
30        40    n           4
8
12
16
                -•—i
                                  STA 47
                                  30 JULY 1974
                   METALIMNION
                                                                                   STA 23
                                                                                   13 AUG  1974
                                                                         BOTTOM
                Figure 95.  Vertical profile of incubator  productivity  at station 47 on
                            30 July 1974 and  station 23 on 13 August 1974.

-------
96).  For Station 30  in early August incubator  productivity increased
linearly  from 1 m to 11.5 m (Figure 96);  in  mid-August  productivity
remained the same  from  1  m to 4 m, where  it increased and reached
a plateau at 15 m  in  the  metalimnion (Figure 97).  Station 34 in mid-
August had a profile similar to Station 30 in  Figure 97 although the
euphotic  zone extended to only 11 mm.   Station 36 in  mid-August  had
a nearly linear profile sinilar to  Station 30 (Figure 96) except it started
at 3 m.   Station 39 on late  October had minimum productivity at 5  m
which increased at  7  m to nearly the level at 1 m (Figure 97).  Pro-
ductivity at Station  48 in  early  August had a  maximum at 4 m and
decreased  to nearly the same level as at 1 m (Figure 98); in mid-
August productivity  remained nearly  the  same for the  first five meters,
increased  slightly at 9 m, and  it decreased to a minimum level  at  13
m (Figure 98).   Productivity at Station 52 in late  July had a sharply
defined maximum  at 3 m  (Figure 99).   In  mid-lake areas phytoplahkton
accumulated in the  lower  epil imnion  and metal imnion.   Station 30
(Figures 96 and 97) showed this trend in incubator productivity pro-
files.  The profile  for 14 August is  supported by  chlorophyll  a (uncor-
rected) data (Table  66).   Productivity at Station 36 on 15 Aug~ust
showed a marked  increase toward the metalimnion.  However, chloro-
phyll a. concentration  and  productivity do not agree.
     TABLE 66.  VERTICAL DISTRIBUTION OF UNCORRECTED
         CHLOROPHYLL a CONCENTRATION  AT  STATIONS
                      30 AND 36  IN  AUGUST  1974
     Station 30
     Depth
      (m)

         1

        14

        16

        20
  14 August
Concentration
  (mg/m3)

      2.7

      3.9

      3.8

      3.5
Station  36
 Depth
  (m)

    1

   16

   19

  23
  15 August
Concentration
  (mg/m3)

     3.9

     3.9

     3.6

     5.5
                                  250

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£10

Q.
0)
Q
  15
                          8
   Incubator Productivity (mgc/rrf3- h)
12         16   n           10         20
                                  STA 25
                                  13 AUG 1974
  20
                                                                       METALIMNION
30
40
                                                   STA 30
                                                   1 AUG 1974
                Figure 96.  Vertical profile of incubator productivity  at station 25 on

                            13 August 1974 and station 30 on 1 August 1974.

-------
INJ   £10
en   QL
ro   fli
      15
      20
                              8
             M ETA LIMN I ON
   Incubator Productivity (nig C/nr'-h)
J2	16    Of	10
                                       STA 30
                                       14 AUG 1974
20
                                                                             BOTTOM
30
40
           STA  39
           27 OCT 1974
                    Figure 97.  Vertical profile of incubator productivity at station  30 on
                                14 August  1974 and station  39  on 27 October  1974.

-------
ro oi
en  _ '
co -E

   Q.
   0)
  Q
    15
    20
 10
—p.
 20
—i—
l  '• l
                                         Incubator Productivity (mg C/m3- h)
 30
~T~
                                                40
                                    STA 48

                                    4 AUG  1974
                       METALIMNION
                                                   10
20
30
40
                                                                         STA 48

                                                                         16 AUG 1974
                                                          METALIMNION
                 Figure 98.  Vertical  profile of  incubator productivity at station 48 on

                             4 August 1974  and  16  August 1974.

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-t=>  0)
   o
     15
     20
                  10
20
      Incubator  Productivity (mg C/m3- h)
_30	40	    n^	  10
                                          STA  52
                                          27 JULY 1974
                            BOTTOM
20
30
                                                                                         STA  73
                                                                                         30 JULY 1974
                                                                             METALIMNION
                 Figure 99.
 Vertical profile  of  incubator productivity  at station 52 on
 27 July 1974 and station 73 on 30 July 1974.

-------
    In western  Lake Erie productivity increased linearly with depth
at Station 61 in late July similar to Station 30 in Figure 96.  Produc-
tivity at Station 66 in late July had a profile similar to Station 52
(Figure 99) with a maximum at 5 m, but the maximum was  not
quite as sharply defined.   Productivity  at Station 75 in early Sep-
tember resembled Station 30 (Figure  96) although the increase was
not quite  linear.

     Central Lake Erie  showed higher  relative  dark bottle 14C
uptake (dark bottle activity) than western'Lake  Erie.  Central basin
mean dark  uptake increased during  thermal stratification from  18
percent in early August to  24  percent in  mid-August and  decreased
after fall overturn to 12 percent in late October.  Relative dark
uptake ranged  from 3-34 percent and 3-58 percent for early and
mid-August, respectively.   Relative dark uptake of 560 percent and
630  percent at Station 23 on  13 August and 77 percent at Station 73
on 30  July  is considered aberrant  and unexplainable.   Western  Lake
Erie relative dark uptake remained at the same levels throughout
the season,  as mean rates  were 6  percent,  8 percent, and 7 per-
cent (excluding  Station 61)  for  late July,  early September, and late
October,  respectively.  The mean relative  dark uptake for all  sam-
ples during the season was 14  percent.   For incubator studies  in
the eastern tropical Pacific Ocean, Jones et al . (1953) reported
relative dark 14C  uptake of 16-22 percent for productivity experi-
ments lasting four to eight hours.   Larson (1972) reported relative
dark uptake from 4-70 percent during  i_n situ   productivity studies
in Crater Lake.   Relative dark 14C uptake of 6 percent has been
obtained in western Lake Erie (Verduin, personal communication  );
the western basin value  found  in  1974 agree with this  estimate.
Obviously,  higher relative dark uptake drastically reduces light
bottle uptake when corrected  by subtraction.

      Primary  productivity at one meter in  central  and western
Lake Erie  during  1974 showed  high correlation (r = 0.92) with
uncorrected chlorophyll ji concentration,  which is a phytoplankton
biomass  indicator (Figure  100).  The correlation exceeds  by three-
fourths that one reported by  Glooschenko et al.  (1974) for mean  values
per cruise  of  chlorophyll a_ and incubator productivity  in  surface
water in  all three basi n s.   Glooschenko  et al.  called  the  slope of
the graph the assimilation  number, the units of which are mg C/mg
chlorophyll a-h.   Glooschenko's mean assimilation  number  of  1.93
mg  C/mg chlorophyll  a-h  agreed  to  within 10 percent of that for
1974.                 ~
                                   255

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              100
               80
             o
             01
               60
             o 40
             "ra
             .Q
             3
             U
               20
 Figure 100.
                           y - 2.13 x + 2.04

                           r - 0.92
0        10       20       30       40       50
       Uncorrected Chlorophyll a Concentration (mg/m3)


 Relationship of incubator  productivity to  uncorrected

 chlorophyll a  concentration at  1  M depth.
                  100
                            20       40       60

                            Total Phosphorus Concentration
                                                     80
                                            100
Figure 101 .   Relationship of incubator  productivity to  total  phos-

               phorus  concentration at 1  M  depth.
                                   256

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      The relationship  between incubator primary productivity and
nutrient  concentration  in central  and western  Lake Erie  during  1974
is not clear.   From the concentrations of total and soluble reactive
phosphorus  and total inorganic ammonia,  and nitrate-nitrite nitro-
gen in the two basins, only total  phosphorus correlated with incuba-
tor productivity (r = 0.68) for lake water samples from the one
meter depth (Figure 101>  Brydges (1971) found  that in western
Lake  Erie station averages of chloropyll  a from a  composite
sample of 1.5 m  and 7.5 m water were  positively correlated with
total  phosphorus at 1 .5  m for the years  1967-1969.  Megard (1972)
reported that for eutrophic Lake  Minnetonka ,  Minnesota total phos-
phorus in the range of 0-170 mg/m3  (Hg/1) was linearly  correlated
with daily maximum photosynthesis per unit volume of water  during
the months of July, August, September.   Brydges (1971) also found
that soluble phosphorus, nitrate-nitrite nitrogen,  and ammonia
nitrogen did not correlate  with chlorophyll si.

    Light energy penetrating the surface waters in central  Lake Erie
was transmitted more readily than in western Lake Erie during ther-
mal stratification in August (Table 67> The mean euphotic zone  in
central Lake Erie was 2.4 times deeper than in western Lake Erie.  In
mid-August light transmission improved slightly.  Upon lake overturn
the euphotic zone in central Lake  Erie  was only 30 percent deeper than
in western Lake Erie.  Verduin (1954)  reported that dissolved pigments
have  not been observed in western Lake Erie, and that differences in
light transmission were attributable to  suspended particles.  The same
is assumed for central Lake Erie.

    Incubator productivity represents maximal carbon assimilation
 rates that  result from optimal light  intensities.  A rough approxi-
 mation of incubator light intensity assumes  that full light intensity
 measured by the photometer (10.5 mA) equals 10,000 foot candles
 (Saunders  et al. 1962) during the  brightest  days.   Therefore,
 since an average of O.9 V amps of relative   light intensity reaches
 the tops of the bottles in  the incubator under clear  water condi-
 tions, approximate light intensity is  9000 lux.  Tailing (1966)
 stated that the light-saturating range of  Asterionella communities
 in English lakes  is 8000-10,000  lux.  Tailing (1966), using an
 incubator equipped  with daylight  fluorescent lamps,  converted incu-
 bator light  intensity  to quantity of photosynthetically active radiant
 energy  (400-700  nm)  by the conversion factor of 4.1  kerg/cm
 per  sec per kilolux.   Therefore, 37  kerg/cnrf7 per sec   (9 x 4.1)
 approximates the radiant  energy received by phytoplankton samples
 in the incubator  during the 1974 study.  If the areal and time unite
 are  changed to  m2 and h, respectively,  the resulting radiant
                                   257

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                   TABLE 67.   MEAN SECCHI DISC AND EUPHOTIC ZONE DEPTHS
                 FOR CENTRAL  AND WESTERN  LAKE ERIE FROM JULY-OCTOBER 1974
        No.  of Stations
                       Basins
Secchi disc  (m)
                                                                              Euphotic Zone  (m)
01
oo
         Cruise 6
              5
              5
Cruise 7
     8

Cruise 8
     4

Cruise 10
    11
     5
                       central
                       western
                                central
                                western
                                central
                                western
    4.5
    2.0
    6.0
    1 .0
    3.0
    2.0
12.0
 5.0
                                                                                   14.5
                                                                                    3.5
 8.0
 6.0

-------
energy of approximately 1 x 1012  erg/nr£  per hoir  falls near the
maximum carbon uptake rates on the light-saturated  portions of
photosynthesis-light  intensity curves  published by Stadelmann,
et al. (1974) for Lake  Ontario phytoplankton communities.

      Photosynthetic  productivity per  unit volume of water reflects
phytoplankton densities in the  water column at a particular  depth,
but the relationship is  not a simple one to one correspondence.
Tailing (1966) found for English lakes a broad correlation from
April to June between  population   density  (cell  number) and gross
photosynthetic rate per unit volume of  water.  Blelham Tarn had
population densities  and photosynthetic   rates two  to three  times
greater than Windermere  North Basin.  In  both  lakes  phytoplankton
from below  the  surface showed  greater population   densities and
greater photosynthetic  rates than surface phytoplankton.   Verduin
(1960) found that a five-fold increase in population density accom-
panied a  doubling of net  photosynthetic rate per  volume of water,
when the phytoplankton community changed from  June to August,
1957.   An explanation  may lie in the specific  photosynthetic rate
of the phytoplankton.   Megard (1972) defined the specific photosyn-
thetic rate mg C/m3-da^mg Ch1or a/m3 which is  the  equivalent  of the
assimilation ratio when calculated per  hour.  Tailing (1966) used
both cholrophyll  a and  cell number  per unit volume of water as
measures of population density, and  Verduin (1960) used  phytoplank-
ton volume per  unit volume of water.  Specific  photosynthetic
rate decreased with increasing depth during in situ  productivity
studies on Lake Tahoe  (Kiefer et al. 1972).  The  1974 incubator
studies re-veal that at  the same  light intensity at Station 47 on  12
August the  1-m and 13.5-m samples yielded specific photo-
synthetic rates of 2.5  and 3.7 mg C/mg chlor a^h,  respectively.
This  increase of 48 percent resulted from a 15  percent increase
in the incubator  productivity from  13 to  15 mg  C/m3
-------
 density ( mg chlor a/m3,  Megard,  1972).  For these reasons incu-
 bator productivity is a metabolic  index  of population density as
 Saunders et al. (1962) believed when they  exposed samples from
 different depths to a light intensity  of 500 foot candles.  The
 strong correlation between incubator  productivity and chlorophyll
 a concentration at the one  meter  depth  in 1974 emphasizes their
 contention.

      Both incubator and  i_n situ productivity data for 1974 remain
 uncorrected for excretion of  organic matter, respiration losses,
 and grazing because they were not quantified by  experiment.  Ex-
 cretion of organic compounds may cause significant underestimates
 of productivity.  Fogg et al. (1965) found that  during  a four-hour
 experiment  approximately 34 percent of the initially assimilated
     was excreted  by diatom dominated communities in English
         Wtth thS 14C tecnniclue no way  exists to  measure loss of
        during  breakdown  of organic compounds in respiration
 (Kiefer et al.   1972).  The  reaction involved  is:

                 "CHgO  + 02	» *C02 + HgO.

 Significant grazing of phytoplankton  standing crop.may reduce pro-
 ductivity.   Parkos et al. (1969) felt that grazing  may be impor-
 tant in localized areas  of lakes but should not cause the large
 variations in productivity they observed  in each of the  four Great
 Lakes they investigated.  Verduin (1952) felt that grazing was in-
 significant in western  Lake Erie.   Glooschenko et al. (1974) felt
 that the zooplankton in  Lake  Erie, which are characterized by
 protozoans,  rotifers, and cladocerans, consume detritus and bac-
 teria more than phytoplankton.

      For the 1974 incubator studies  14C uptake was assumed  to be
 linear at constant  light intensities.  The literature gives varying
 results.  Barnett and Hirota  (1967)  found that at  constant light
 intensity the rate of 14C  uptake was  constant during a two-hour
 incubation.  In a second  experiment of four  hours  duration,
 Barnett and Hirota used  phytoplankton concentrations ten times
greater, and light intensity was half  of the first  experiment.
They found that 14C uptake rate decreased to 62  percent of the
 rate at one hour.

      Fogg et al.  (1965) found that photosynthesis was  proportional
to incubation time  under  constant light intensity in situ  and in
the laboratory, but organic matter was excreted at an almost
                                  260

-------
constant percentage of the photosynthetic uptake.

     Extracellular 14C adsorbed to phytoplankton leads to  overesti-
mates  of productivity.  McMahon (1973)  showed  that rinsing filters
with 100 ml of  distilled or  filtered lake  water removed extra-
cellular   C, which  had led to  erroneous conclusions concerning
self-absorption.   The  investigator assumed that  the acid and  fil-
tered lake water  rinses used in 1974 adequately removed
extracellular 14C.

     Estimation of phytoplankton  productivity at  several stations
during  different times of  the day may exaggerate productivity
relative to each other.  Vollenweider and  Nauwerck (1961) found
during  In  situ studies  on  Lake  Erken, Sweden the interval of
0530-0930 yielded productivity per unit area of water one  third
of the daily total of  a series of five  four-hour  time blocks.
Holmes and Haxo  (1958) demonstrated changes in photosynthesis
throughout the day in  incubator studies at  a station in the tropical
eastern Pacific Ocean.  Maximim photosynthesis occurred  at
0800-1000.  Verduin (1957)  found that the  period 0700-1000
in western Lake  Erie yielded maximal  net  photosynthetic rate per
unit volume of  water two-thirds greater than during the intervals
1000-1300 and  1300-1600.  All  times are given  in EST.

     Whether the 14C method estimates net or  gross  productivity
remains unsolved.   Saunders (1964) felt that because  the  sum of
a series of short experiments over  a day  exceeded the estimate of
a single full day exposure,  the series estimated' gross productivity
and the single  exposure net.  Vollenweider  and  Nauwerck (1961)
suggested that  productivity measured by 14C lies between net and
gross.

      Both incubator and  in  situ productivity estimates  made by
the  14C method include combined contributions by phytoplankton
and bacteria.  Cody (1972)  states that the  measurement of carbon
assimilation is complicated by  autotrophic  bacteria, both  chemo-
synthetic  (aerobic) and photosynthetic (nonsulfur which  are aerobic
and sulfur which are  anaerobic).  The relative  amount of bacterial
assimilation is unknown.

      Phytoplankton,  zooplankton, and  bacteria all play a role  in
dark 14C  uptake  (Gerletti 1968).   Sorokin  (1965) described
three  groups of bacteria  involved in aerobic decomposition of organic
                                   261

-------
matter which account for the major part of dark CO2 assimilation in
surface  layers  of eutrophic and  mesoeutrophic lakes.   Another  group
of bacteria intermediate between heterotrophic and chemosynthetic
oxidizes simple organic products of anaerobic decomposition.  A
third group are chemoautotrophs that utilize  CO2  in the syntheses  of
all  their organic compounds.

      During ir,  situ studies on Lake Maggiore, Italy,  Gerletti
(1968) found that below  the optimal   level of illumination (where
maximum  photosynthesis is expected to occur) relative  dark uptake
of    CO2  (dark bottle activity expressed as percent of the cor-
responding light bottle  activity)  increased.  In situ experiments
at Rattlesnake  Island during  1974 support GeFlettT.   Relative dark
14C uptake on  21  July  was 2 percent at  one meter,  increasing
to 14 percent  at five meters; for 1O September, 2  percent  at one
meter,  increasing to 33 percent at six and eight meters; and on
6 October, 6 percent increasing to  35  percent at  four meters.
However,  in the incubator studies at an  optimal light intensity,
relative dark bottle rates  ranged from  1-58  percent and were
especially high in the central basin during late July to  mid-
August.   On the hottest summer days  incubator temperature
remained  within 2°C of the lake surface temperature.   Since
the temperature from surface to lower epilimnion did not vary
by more than  2 C on the average over the sampling season,  the
temperature differential between incubator and sample depth is
negligible.  Even though light intensity in the incubator isoptimal,
a significant increase in relative dark  bottle activity occurs.
The  source of this uptake  is  not specifically known,  although the
bottle surface  effect on  bacteria may stimulate their growth
(Gerletti 1968).   Menon et al. (1972) reported bacterial densities
of 3.3-3700 x  I03/ml   and 3.4-79O x  104/ml for central and
western  Lake  Erie,  respectively.  Vertical distribution was uni-
form until stratification,  when  hypolimnion  bacterial densities
increased  more than epilimnion  densities.  Bacteria in  late
August utilized organic matter from excretion and degradation
products of blue-green and green algal  blooms to attain maximum
densities.

      Morris et al.   (197V) found that with marine  phytoplankton
relative  dark uptake of 14C became greater with smaller popula-
tion  densities.   Smaller phytoplankton  densities in both  central
and western Lake  Erie in  1974 yielded  higher relative dark
uptake,  but the relationship is non-linear (Figure  102).   Relative
                                   262

-------
  140
  120
2-100
o
 D)
 E

~ 80
 2
 D.
 n
 .0

 o
 a>
   60
   40
    20
     0'	6/i          0.2         073          0-4
       Ratio of Dark Bottle Activity to Light Bottle Activity
                                                0.5
 Figure 102.
Relationship of mean  relative dark 14C  uptake

to mean incubator  productivity at  each station

in central and western Lake Erie.
                                 263

-------
 dark uptake increased with decreasing turbidity (Figure  1O3),  which
 supports the previous relation.

     No relationship was noted between dark  14C  uptake  and tempera-
 ture.   For both relative and absolute values equally high and low
 rates were observed at temperature ranges of 10-13eC and 18-24*0.

     In situ productivity vs, depth profiles show the  effect of decreas-
 ing light intensities on carbon assimilation rates, whereas incubator
 productivity profiles at constant light  intensity show relatively little
 change in carbon  assimilation rates.  The shipboard counterpart to
 Rattlesnake Island, Station 67, did not have significant changes in
 vertical distribution of productivity.  In situ profiles show that pro-
 ductivity at one meter and deeper closely parallels  light
 transmission in all three experiments  down to a  relative light
 intensity of approximately 10  percent of the  surface light intensity.
 Such  parallelism indicates that phytoplankton populations are
 homogeneously distributed, at least down to  the level of 10
 percent of  the  surface light intensity.   Rodhe (1965) found that
 the  slopes  of assimilation curves of  nine lakes  closely agreed
 with the  slope  of the  most penetrating  component  (usually green)
 of subaquatic light at a level from  1-12.5 percent  of the sub-
 surface intensity  of the  component.

      Incubator  data showed that the phytoplankton  in both basins
 survived  the light intensity of the water bath.   For example,  a
 sample of lake water  from four meters at Station 53 on 6
 September  from  a  relative  light intensity  (775 y A) had a pro-
 ductivity  potential nearly  20 percent  greater  than  a sample from
 one  meter,  which received about a 370 times greater  relative
light intensity.  This suggests that the  water at Station 53 circulates
 completely  down  to four  meters so that the cells  at Four  meters
 do not remain  in total darkness, otherwise they may have been
 injured by the  incubator light  intensity  and would  not have func-
 tioned photosynthetically,  or  if so, then at a reduced rate.
 Water temperature and oxygen concentration  remain unchanged
 from  one meter  to four meters which  supports  this hypothesis.
 Keifer  et al.  (1972) reported that phytoplankton from  100-400
 m in Lake  Tahoe survived light  intensity increases  of  107, as
 When  the samples  were  incubated at  a light intensity 40 percent
 of the surface, they had  photosynthetic  potentials  per unit of
 chlorophyll a_ slightly  less than  phytoplankton at 75  m  in the
 euphotlc zone (85).

     The incubator productivity-total  phosphorus relationship


                                   264

-------
O
o

x

X

 o
   30
5
x

il20

1
o
 o
co
x

 o
Q
«4-
 o
 o
10
         DATA FROM STATIONS 30. 47.48, 67, 75. 76

         JULY - OCTOBER 1974
                                                   0.8
                                                           1.0
          0.2         0.4         0.6

                 Light Transmission —

RATIO OF PHOTOMETER READING AT SAMPLING DEPTH TO PHOTOMETER

         READING ONE  METER ABOVE SAMPLING DEPTH
                                                  14
     Figure  103.   Relationship of relative dark   C uptake

                   to light transmission.
                                265

-------
 may  indicate that total phosphorus is  an indicator of phytoplankton
 densities.  Brydges (1971) suggested that if total  phosphorus  concen-
 trations were reduced, there would be less algae.  The 1974 incu-
 bator data  support Brydges' argument.

      The parellelism in  the _in  situ productivity-light transmission
 curves in Figure 92  suggests that  light is  a  controlling factor in
 primary  productivity in western Lake Erie.   Since  total phosphorus
 concentration is lenearly related to incubator productivity at the
 one-meter  depth,  then both light and total  phosphorus may together
 limit primary productivity.  If the light-in_ situ  productivity  re-
 lationship holds for central Lake Erie,  then  both  factors may be
 limiting in central  Lake  Erie also.

 SUMMARY

      Western basin incubator  productivity  was 3.5 times greater
 than  central basin  incubator productivity in the summer and  1.5
 times greater in the fall.  Incubator productivity  estimates were
 comparable to those  in 1970.  Central basin  incubator productivity
 decreased in  late  summer and increased upon fall overturn.   West-
 ern basin incubator productivity  declined throughout the season.

      In situ  productivity-light intensity  curves for western Lake
 Erie  showed  that phytoplankton are photosynthetically active at
 lower light intensities in  October,  as  opposed to July and Septem-
 ber,  and that maximal productivity is reached within a  narrower
 range of  light intensities.  Maximum productivity  occurs at ap-
 proximately one meter.   In all three m_ situ  experiments  relative
 productivity curves lay parallel  to  light transmission curves  down
 to a level of  approximately ten percent  of  the surface light  intensity.

      Estimated  errors for the  1974 methodology showed that  a
 slightly greater  total error existed than was  normally accepted
 in other studies cited.  Each sample lost an average  of 14 percent
 of its initially assimilated 14C when merthiolate fixative was  used.
This  fixation  effect had the greatest uncertainty  in the  estimate of
total  error.

      Incubator  productivity profiles showed several  forms.   Maxi-
 ma were  located  at one meter,  slightly below one meter,  and
some mid-lake  central basin profiles increased toward the
                                   266

-------
metaHmnion.   Lower maximum to minimum incubator productivity
ratios indicate that western  Lake Erie waters are mixed more
thoroughly than central Lake Erie waters.
                                        14
      Central  basin relative  dark bottle   C uptake averaged  three
times greater  than western basin relative dark bottle uptake.
Central basin relative dark bottle uptake  increased during thermal
stratification,  yet  western basin  relative  dark bottle uptake re-
mained  rather constant.   Higher  relative dark bottle uptake
occurred  in areas of less turbidity and phytoplankton densities.
The  effect of temperature on relative dark bottle uptake was not
evidenced.

      Incubator productivity  correlated with uncorrected  chlorophyll
a concentration and total  phosphorus concentration at the one  meter
depth.  The incubator productivity-total  phosphorus, and relative
in situ  productivity-light  transmission relationships  suggest that
light  and  phosphorus  together operate as  limiting factors in central
and western Lake  Erie.
                                   267

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      14C uptake with  length of  Incubation period in  natural phytoplankton
      populations.   Limnol. Dceanogr.  12:349-353.

 Beeton,  A. M. and W. T.  Edmondson.   1972.  The eutrophication
      ptoblem.  J.  Fish.  Res. Bd.  Can. 29:673-682.

 Brydges, T.  G.   1971.   Chlorophyll a-total phosphorus  relationships in
      Lake Erie.   Pages  185-190  un Proc.  14th Conf. Great Lakes Res.,
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 Cody, T.  E.   1972.   Primary productivity in the western basin of Lake
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 Fogg, G.  E., C. Nalewajko,  and W.  D. Watt.   1965.   Extracellular
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 Gachter,  R., R.  A. Vollenweider, and W. A.  Glooschenko.  1974.
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 Gerletti,  M.   1968.   Dark  bottle  measurements in primary productivity
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 Glooschenko,  W.  A.,  J.  E. Moore, M. Munawar,  and R. A.  Vollen-
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Jones,  G.  E.,  W.  H. Thomas,  and  F. T.  Haxo.   1958.   Preliminary
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     Serv. Spec.  Sci. Rep.  Fish.   279:79-86.

Kiefer,  D. A.,  O.  Holm-Hansen,  C. R.  Goldman,  R.  Richards,  and
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     populations.  Limnol.  Oceanogr.  17:418-422.

Larson,  D. W.   1972.   Temperature, transparency,  and phytoplankton
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McMahon,  J. W.   1973.  Membrane  filter  retention—a source of error
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Megard,  R. O.   1972.   Phytoplankton, photosynthesis,  and phosphorus
     in  Lake  Mi nnetonka,  Minnesota.    Limnol. Oceanogr.   17:68-87.

Menon,  A.  S.,  W. A.   Gollschenko, and N.  M.  Burns.  1972. .Bacteria-
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     15th  Conf. Great  Lakes Res., Int.  Assoc. Great Lakes Res.

Morris,  I., C.  M. Yentsch, and C.  S. Yentsch.   1971.  Relationships
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Parkos,  W. G., T. A. Olson, and T.  O. Odlaug.   1969.  Water quali-
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     Bull.  17.   121. p.

Rodhe,  W.  1958.  The primary production in lakes:   some results
     and restrictions of the 1^C method.  Rapp* P.-V. Reun.  Cons.
     Int.  Exolor.  Mer.  144:122-128.

          1965.   Standard correlations between pelagic photosynthesis
      and light.  Pages 365-381  In C. R.  Goldman (ed.)  Primary
      productivity in aquatic environments.   Mem. 1st.  Ital.  Idrobiol.
                                  269

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      Dott.  Marco de March!  Pallanza Italy,  18  Suppl.,  Univ. Calif.
      Press, Berkeley , Calif.

Saunders,  G.  W.   1964.   Studies of primary productivity in  the Great
      Lakes.   Univ. Mich.  Great Lakes  Res. Div. Publ.  11:122-22Q.

Saunders, G.  W.,  F. B. Trama, and R.  W. Bachmann.   1962.  Evalu-
      ation  of  a modified C   technique for estimation  of  ohotosynthesis
      in large  lakes.   Univ. Mich.  Great Lakes  Res. Div. Publ.  8.
      61 p.

Sorokin,  J. I.  1965.  On  the trophic role of chemosynthesis and
      bacterial biosynthesis in  water bodies.  Pages  365-381   in C. R.
      Goldman [ed.] , Primary productivity in aauatic environments.
      Mem.  1st.  Ital.  Idrobiol.  Dott.  Marco de March!  Pallanza  Italy,
      18 Suppl.,  Univ.  Calif.  Press,  Berkeley.

Stadelmann, P., J. E. Moore,  and E. Pickett.  1974.  Prirrary production
      in relation to temperature structure, biomass concentration and
      light conditions at an inshore and offshore station in Lake Ontario.
      J. Fish.  Res. Bd. Can.  31:1215-1232.

Strickland, J. D. H. and T.  R.  Parsons.   1968.  A oractical hand-
      book of seawater analysis.  Fish.  Res. Bd.  Can. Bull.   167.
      311 p.

Tailing, J. F. 1966.  Photosynthetic behavior in stratified and unstra-
      tified lake  populations of a  planktonic diatom.  J. Ecol.  54:Q9-127.

Verduin,  J.   1951.   Photosynthesis  in naturally reared aquatic commu-
      nities.   Plant Physiol.  26:45-49.

	.   1952.   Photosynthesis and growth rates  of two  diatom
      communities in western Lake Erie.  Ecology 33:163-168.

	.   1954.   Phytoplankton and  turbidity in  western  Lake Erie.
      Ecology  35:550-561 .

	.   1956.   Energy fixation and utilization  by natural communities
      in western Lake Erie.  Ecology  37:40-50.

	.   1957.   Daytime variations in  phytoplankton photosynthesis.
      Limnol.  Oceanogr.   2:333-336.
                                  270

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          1960.  Phytoplankton communities  of western Lake Erie and
     the CO2 and O2  changes associated with them.   LimnoT. Ocenangr.
     5:372-380.

          1962.  Energy flow through biotic  systems o^ western Lake
     Erie.   Pages 107-121 in H. J.  Pincus(ed'), Great Lakes  basin.
     Am. Assoc. Adv.  Sci.  Publ.  71.

Vollenweider,  R. A., M. Munawar,  and P.  Stadelmann.   1Q74.   A
     comparative review of phytoplankton and primary production  in
     the Laurentian Great Lakes.   ). Fish. Res. Bd. Can.   31:73Q-
     762.
                                 271

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                              SECTION 9

           ZOOPLANKTON DISTRIBUTION IN THE CENTRAL
               AND WESTERN  BASINS OF LAKE ERIE

                 Donna  D. Larson and David E.  Rathke
                 Center for Lake Erie Area Research
                       The Ohio State  University
INTRODUCTION

      Zooplankton samples were  collected during the 1974 field  season in
the western  and central basins of Lake Erie as part of the EPA Nutrient
Control Project  funded by the U.S. Environmental Protection Agency and
administered by The Ohio State  University, Center for Lake Erie  Area
Research.  This phase of the nutrient study was designed to provide  a
comprehensive collection  of information on  the species and  numbers of
the major zooplankton groups in  the western and central basins, in addi-
tion to  relating biomass of these animals to other  physical,  chemical
and biological parameters.

METHODS

      During  six cruises  between May and November of 1974, 51 stations
throughout the western and central basins were visited (see Overview,
Section 1, Figure  1).  Zooplankton samples were  collected by vertical
tow using a  0.5  meter, 80-micron mesh net which was raised mechani-
cally at a constant rate.   Organisms  were  relaxed with club soda  and
then preserved  in five  percent MgCOs buffered  formalin.

      At the  Columbus  laboratory,  samples  were counted using  a strati-
fied method  allowing for  enumeration  of approximately 200 adult crust-
aceans  and 250-300 immature crustaceans and  rotifers.  With a Wild M5
binocular dissecting microscope  at 50x in conjunction with  a Ward  zoo-
plankton counting wheel,  copepods,  cladocerans and rotifers  were identi-
fied to  species,  excepting  immature forms.  The open chamber permitted
manipulation and dissection of individuals when  necessary for identification.
                                  272

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    Distinction  was made between  male and female adult crustaceans,  and
all  gravid or egg-carrying female  animals were  enumerated separately and
numbers of young or  eggs noted.   Nauplii  of the cyclopoid and calanoid
species were counted together,  but the nauplii  were grouped  into three
size classes.  The cyclopoid  and  calanoid  copepodids  were each  separated
into three size  classes.   Adult cladocerans were also  placed  into three
size classes.  The rotifers were  identified to  species  whenever possible.
All rotifers  carrying  eggs are listed separately,  and number of eggs  per
individual  recorded.

      For  routine zooplankton identification the taxonomic references
used were:  Ward  and Whipple (1959), Pennak  (1953)',  Jahoda (1948),
Voigt  (1957), Deevey  and Deevey (1971), Brooks (1957),  Eddy and  Hod-
son (1961) and Ahlstrom (1940, 1943).  Occasionally problem species
were  sent to other  taxonomists for confirmation.

    Numbers per cubic meter and milligrams  per cubic  meter of dry
weight were calculated and basin averages determined  for each  species
and major group.   Biomass values for the  rotifers were obtained by
assigning  each species a geometric configuration approximating  its shape,
determining  a volume and assuming a specific  gravity  of one.   Dry  weight
was calculated by taking  10 percent of the wet weight  as recommended
by  Ruttner-Kolisko  (1974).  Biomass  estimates for the cladocerans  and
copepods were obtained from  Dumont, et  al. (1975), Makarewicz (1974),
Nauwerck  (1963), Wilson and Roff  (1973) and through personal communica-
tion of unpublished  data  by J.B. Wilson of the Canada Centre for Inland
Waters.

    Based on depth and  chemical  parameters the western and central
basins were further divided into the western basin, Sandusky sub-basin,
western central  basin and eastern  central  basin  (Figure  104). These sub-
basins proved valuable  in evaluation of  distribution of  major zooplankton
groups and individual species as the seasons progressed.

NET  EFFICIENCY
    Differences  in  net mesh size may result  in  disproportionate numbers
of zooplankters being  captured.  If the mesh is large many small organisms
are lost,  but small mesh nets may cause  serious  clogging problems result-
ing in an  inaccurate  representation of numbers or organisms per cubic
meter of water.  Many  zooplankton surveys have assumed a net efficiency
of  100  percent,  and therefore numbers  of organisms presented  are prob-
ably lower than actually occur  in the water column.   According to
McNaught, et al. (1975), estimates of zooplankton blomass based on 100
percent  net  efficiency are usually  low by a factor of two and often  by
                                   273

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               Figure  104.   Sub-basin map.
                                               ZOOPLANKTON
                                             COLLECTING STATIONS
                                                  1967 - 1968      :
                                             DATA SOURCE: Davis, 1969
Figure 105.   Zooplankton  collecting stations  1967-1968,
                              274

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as much as a factor of ten.   The average  net efficiency  during  this
study, as determined by two flow meters mounted on the inside and
outside of the net, was approximately 70 percent based on  spring,
summer and fall measurements.   Numbers per  cubic meter were ad-
justed based on this  percentage.

PREVIOUS  STUDIES

      During the past ten years there have been three extensive Lake
Erie  zooplankton surveys.  Davis (1969) made two transects  of  the en-
tire  lake in July and October of  1967 and a partial  transect  in January
of 1968.  He  visited 30  stations  located mid-lake (Figure 105) and iden-
tified and counted copepods,  cladocerans and rotifers.   Watson  and
Carpenter (1974) sampled crustacean zooplankton at 30 stations  through-
out the western, central and eastern basins from April  to  December of
1970  (Figure  106).   Patalas  (1972) traversed the entire  lake  to  sample
crustacean zooplankton at 34 stations during two cruises between June
and August  of 1972  (Figure 107).

      A  methods comparison of recent Lake Erie zooplankton surveys is
presented as  Table  68.   Differences in sampling techniques,  length of
field  season,  cruise frequency,  net size,  counting techniques and the
plankton groups examined are  apparent when the surveys are contrasted.
These differences in technique make comparison of surveys difficult.

RESULTS

Total  Zooplankters

      Peak  concentrations of total zooplankters were observed during early
June and early September in the western central and eastern central sub-
basins,  but this bimodal  pattern did not occur in the  western basin and
Sandusky sub-basin  (Figure  108, Table 69).   Zooplankton numbers per
cubic meter increased rapidly in the western and central basins after a
spring low,  and remained stable during June and July.   Populations  in
the two western sub-basins maintained this high level from mid-August
through the end of October,  while levels in the central  basin dropped
sharply in mid-August.   This low was  followed by  an increase  in early
September  and  a decline at the end of October.

       Discussion of  the three major zooplankton  groups  will  be  presented
in the following sections.  A list of species identified from  the western
and central basins during 1974 appears as Table 70.
                                   275

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                                               1970 ZOOPLANKTON
                                               COLLECTING STATIONS
                                             DATA SOURCE: \Aatson, 197
  Figure  106.   1970 zooplankton  collecting  stations.
20   0   20   40  60   80 j

      KILOMETERS
                                               1968 ZOOPLANKTON
                                              COLLECTING STATIONS
                                             ATA SCJRCE: Patatas, 1972
 Figure 107.   1968 zooplankton collecting  stations.
                            276

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                        TABLE 68.
 LAKE ERIE ZOO PLANKTON  STUDIES

COMPARATIVE  METHODS
ro
—i
Investigators)
Engel ("1962*)
Davis (1969)
Watson
and
Carpenter (1974)
f>atalas (1972)
Rolan,
Zack and
Prttschau (1973)
CLEAR
(unpublished)
Great
Lakes
Laboratory
(unpublished)
Year
1961
1967-
1968
1970
1972
1973
1974
1974
Season
June-August
July, October,
1967, January,
1968
April -
December
June -
August
September, 1971
to
January, 1973
May -
November
March-
November
Basin,
# Stations
# Cruises
Western Basin
6 cruises
6 stations
All Basins
30 stations
3 cruises
All basins
30 stations
1O cruises
All basins
34 stations
2 cruises
Cleveland Harbor
10 stations
monthly
CB, WB
50 stations
6 cruises
Eastern Basin
25 stations
6 cruises
Collecting
Method,
Net Size
Juday Trap
64 M net
VT, 0.5m, 64M
VT, 0.4m, 64P
VT, 0.12m, 90M
VT, 0.5m, 76 M
VT, 0.5m, 80M
VT, 0.5m, 64M
Groups
Considered
rotifers,
crustaceans
rotifers,
crustaceans
crustaceans
crustaceans
crustaceans
rotifers,
crustaceans
crustaceans
Counting
Method
Sedgewlck
Rafter
cell
Sedgewlck
Rafter
cell
Inverted
microscope
— __
open
counting
chamber
open
counting
chamber
open
counting
chamber

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   1 x 10  _
  1 x 10'
                   AVERAGE ZOOPLANKTON CONCENTRATIONS
                   IN N0./m3 BY SUB-BASIN
A  qj M P J  f J
                                         *  WB

                                         • SSB

                                         • WCB

                                         * ECB
                                                N
                            1974
Figure 108.   Average  zooplankton concentrations  in
               no./m3 by sub-basin.
                           278

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TABLE 69.   AVERAGE 1974 ZOOPUANKTON NUMBERS/m3
               BY BASIN AND CRUISE

1
2
3
/
B
6

Rotifers
Cladocerans
Copepods
Total
Rotifers
Cladocerans
Copepods
Total
Rotifers
Cladocerans
Copepods
Total
Rotifers
Cladocerans
Copepods
Total
Rotifers
Cladocerans
Copepods
Total
Rotifers
Cladocerans
Copepods
Total
Western
1.5 x 1O4
3.0 x 102
3.9 x 1O4
5.43 x 104
2.1 x 105
4.8 x 104
8.6 x 104
3.44 x 105
1.2 x 10^
5.5 x 104
1.2 x 105
2.95 x 105
2.5 x 105
1.4 x 104
5.8 x 10
3.22 x 105
1.6 x 1 O5
3.8 x 1O4
3.2 x 10
2.3 x 1O5
1.9 x 105
1.5 x 104
1.6 x 10*
2.21 x 105
"B"
3.6 x 104
1.1 x 103
5.7 x 104
9.41 x 104
1 . 0 x 1 05
1.0 x 105
1.2 x 1O5
3.4 x 105
4.1 x 104
4.3 x 104
1 .7 x 1Q5
2.53 x 105
1.8 x 1 O5
1.1 x 104
2.7 x 104
2.18 x 105
1.1 x 1 O5
5.6 x 1O4
4.5 x 104
2.11 x 105
1.1 x 1O5
4.5 x 104
3.6 x 104
1.91 x 1O5
WCB
9.3 x 1O4
2.5 x 103
8.6 x 1O4
1.815X 105
3.8 x 1O4
6.4 x 104
2.0 x 1O5
3.02 x 1O5
3.5 x 1O4
5.1 x 104
1.9 x 1 O5
2.76 x 1O5
6.7 x 104
1.7 x 104
4.5 x 1O4
1 . 29 x 1 05
2.4 x 105
6.7 x 1O4
4.1 x 104
3.48 x 1O5
3.6 x 1O4
3.7 x 104
4.7 x 104
1.2 x 10
ECB
3.6 x 1O4
7.6 x 102
3.5 x 1O4
7.176 x 104
6.6 x 1O4
5.3 x 104
2.0 x 1O5
3.19 x 1O5
4.2 x 1O4
8.2 x 1O4
1.8 x 105
3.04 x 1O5
4.9 x 1O4
1.9 x 1 O4
7.6 x 104
1 . 44 x 1 O5
1.3 x 1O5
2.8 x 1O4
4.6 x 104
2.O4 x 1O5
4.0 x 104
5.0 x 104
5.7 x 1O
1.47 x 105
Shore
5.7 x 104
1.7 x 103
7.9 x 1O4
1.377 x 105
7.2 x 104
8.9 x 104
2.0 x 105
3.61 x 1O5
4
4.6 x 10
7.8 x 104
1 .9 x 1O5
3.14 x 105
7.7 x 104
2.3 x 104
6.5 x 104
1.65 x 1O5
2.4 x 1O5
5.9 x 104
4.4 x 104
3.43 x 105
6.0 x 104
5.5 x 104
5.5 x 104
1.7 x 1 O5
                        279

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      TABLE  70.   ZOOPLANKTON  SPECIES  FOUND IN  WESTERN
        AND CENTRAL BASINS OF  LAKE  ERIE, 1974  AND  1975
 Rotifers
 Asplanahna priodonta
 Brachionus angularis
 B.  budapestiensis
 B.  calyciflorus
 B.  oaudatus
 B.  havanaensi-s
 B.  diversicornus
 B.  patulus
 B.  quadridentatus
 B.  ureeolaris
 Chromogaster ovalis
 Cephalodella sp.
 Collotheca pellagioa
 Conochiloides dossuarius
 Conochilis unicornus
 Euchlanis  dilitata
Filinia  longiseta
Kellicottia  longispina
Keratella ooehlearis
K. coahlearis fo. tecta
Keratella arassa
K. quadrata
K. hiemalis
Leaane luna
Rotaria sp.
Hexarthra mira
Notholaa foliaaea
N. aanminata
N. laurentia
N. squamula
Pleosoma lentiaulare
P. hudson-ii,
P. trunoatwn
Pomphlyx suleata
Polyapthra vulgaris
P. doliahoptera
P. ewryptera
P. longiremis
P. major
P. remata
Synahaeta lakowitziana
5. oblonga
S. pectinata
Synahaeta sp.
Tri-chooepoa oyl-Lndriaa
T. multicrinis
T. similis
T. longiseta.
 Cladocerans

Alona affinis
Bosmina longirostris
Ceriodaphnia lacustris
Chydorus sphaerious
Daphnia ambiqua
D. galeata
D. longiremis
D. parvula.
D. retroauzva
Polyphemus pediaulus
Sida crystallina
           Diaphanosoma leuahteribergianwn
           Eubosmina  ooregoni
           Euryaeraus lamellatus
           Holopediim gibberum
           Ilyoaryptus sordidus
           Latonia setifera
           Ledigia quadrangularis
           Leptodora kindtii
           Moina braehiata
           Pleuroxus procurvas
Copepods

Cyclops bieuspidatus thomasi
C. vernalis
Mesoayolops edax
Euayclops agilis
E. speratus
Tropocyclops prasinus
Paracyclops fimbriatus poppei
Diccptomus ashlandii
           D.  oregonensis
           D.  sicilis
           D.  siciloides
           D.  minutus
           Eurytemora af finis
           Epischupa lacustris
           Limnocalanus macrurus
           Canthocamptus robevtcokevi
                                   280

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Rotifers

    Due to  their relatively  low biomass  and taxonomic problems, many
plankton investigators have  chosen to exclude the rotifers from zooplankton
population studies.   Small  in size compared to the copepods and cladocerans,
rotifers were found by Schindler  and Noven (1971) to comprise  no more
than 12 percent of the zooplankton biomass in several lakes characterized
as oligotrophic to eutrophic.   In  contrast,  during  1974 rotifers  in the
enriched western  basin of Lake Erie comprised  6 to  40  percent of the
total zooplankton biomass.   Based on studies in Lakes Michigan and
Huron,  Gannon and  Stemberger (1975) concluded that such high  popula-
tions  of rotifers may be considered  indicative of eutrophic  waters.  Be-
cause their rapid reproductive rates make  them quick to respond to
environmental changes, rotifers  may be  valuable as indicator  organisms.

    Only two investigators  since  1960 have included rotifers in  Lake Erie
surveys.  Secoy  (1962) identified 2O1 species of rotifers from the  island
region  of Lake  Erie in 1960.  When comparing  her study to those  of
Ahlstrom (1934),  Chandler  (1940), Kellicott (1896,  1897) and Jennings (1901)
she found that 106 of the 201  species had been found by more than one  of
the previous workers, and  only six  species were common to all surveys.
Davis  (1969) sampled  in July, October and January and  found  highest
rotifer concentrations  and number of species in the western basin during
July and October.

    The species  list which appears  as  Table 70  includes 47 rotifer taxa
identified from 1974 collections.   Most  of  the species are  planktonic and
ubiquitous  in distribution.  The  littoral-benthic  organisms which are listed
were found only occasionally as accidental members  of  the plankton com-
munity.

 Lake Erie  Western  and Central Basin Rotifers

     During the 1974 May to  November field  season,  rotifer populations
 demonstrated bimodal increases  with a  mid-summer decline (Figure 1O9).
 Numbers were low in early May in  all  but the western  central  basin, where
 large populations of Notholca spp. were found,  primarily N.  laurentiae.

     By early June,  rotifer numbers were  high  in the western and Sandusky
 sub-basins and the community was  dominated by Keratella quadrata, K_.
 cochlearis, Cgnochilus unicornus and Polyarthra vulgaris.   Fewer rotifers
 were  collected in the central basin  during early June.   Dominant members
 of the  central basin community were K. quadrata, Polyarthra dolichoptera
 and P. vulgaris.
                                    281

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  no./m-1
  1 x 103
 1 x 10
                   AVERAGE ROTIFER CONCENTRATIONS
                   IN NO./m3 BY SUB-BASIN
                            1974
                                              WB

                                             SS B

                                             WC B

                                             EC B
                                                N
Figure 109.   Average rotifer  concentrations in
               no./m3 by sub-basin.
                         282

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    The first half of July brought a drop in  rotifer populations,  although
levels  remained  comparatively high  in  the western basin.   The high
western  basin concentrations were mainly due to peak populations of
C.  unicornus  and Brachionus  budapestiensis.

    The second pulse in the rotifer community occurred during  mid-
August  in the western basin and  Sandusky sub-basin,  and early  September
in the  western central  and eastern central sub-basins.  The mid-August
pulse was the result of large numbers of Brachionus angularis in the
western  basin and a peak concentration of Asplanchna priodonta  in  the
Sandusky sub-basin.  The high levels  in early September in the western
central and eastern central basins resulted  from large numbers of C.
unicornus, K.  cochlearis,  Trichocerca spp.  and Polyarthra major.

    By late October of  1974 rotifer populations  had declined in the
central sub-basins but  remained  high  in  the western basin  and Sandusky
sub-basin.  The western basin community was dominated by Synchaeta
spp. and Brachionus calyciflorus and  the Sandusky  sub-basin  primarily  by
Synchaeta spp.

    Rotifers were abundant in both basins during  1974.   The  western
basin is the  shallowest  and most nutrient-rich area, and had  the highest
numbers of rotifers during  most of  the 1974 sampling season.

    Due to high  turnover rates and  rapid restructuring  of the rotifer
community resulting from  environmental changes, sampling  during  1974
may not have been frequent enough to reflect  seasonal successional  patterns
within  this group.

Cladocerans

    Patalas (1972), as  well as other zooplankton ecologists, consider large
numbers of cladocerans to be indicative  of eutrophic conditions.   In 1961
Engel  (1962) noted an increase in cladoceran  populations in  western Lake
Erie since Chandler's  1938-39 survey, and  especially a rise  in the num-
bers of  Chydorus sphaericus, which  is considered an indicator of eutrophic
conditions.   An  increase  in Lake Erie cladoceran populations since 1939
was also noted  by Bradshaw (1964),  who compared  his  1949 data to those
of Chandler (1940) and  Hubschman (1960).

    Watson and  Carpenter (1974) found cladocerans more numerous in  Lake
Erie than in Lakes Ontario and Huron, with populations especially high  in
the western and central basins of Lake Erie.  Patalas  (1972) compared
Lakes  Superior,  Huron and Erie and  noted  that as  eutrophication progressed,
percentages of calanoid copepods declined and percentages of  cladocerans  and
cyclopoid copepods  increased.  Numbers of cladocerans were found to be
highest in the western  basin of Lake Erie during  Patalas1 survey.
                                   283

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Lake Erie Western  and Central Basin Cladocerans

     From  May to November  of 1974,  cladoceran concentrations  in the
four sub-basins were very similar and bimodal  peaks  were concurrent
in all basins (Figure  110).   In early May cladocerans occurred  at low
concentrations.   By the early June cruise high numbers had been reached,
remained stable through the  July cruise, and declined sharply by mid-
August  in all sub-basins.   Early September brought a second  pulse,  nearly
equalling that which occurred in the early summer.   Populations remained
high in  all but the western basin until November.

     The major component of the early summer  cladoceran  pulse was
Bosmina longirostris.  This  cladoceran  reached its highest concentration
in the Sandusky sub-basin and was found in lowest numbers in the western
basin.  Eubosmina coregoni  was the most numerous cladoceran  in the
western  basin, but occurred  in  low concentrations elsewhere,   Daphhia
retrocurva was  also  abundant during the  first  half of the summer, and
occurred in highest concentrations in the western and  Sandusky  sub-basins.

     The early  September  pulse was dominated by Bosmina longirostris,
Eubosmina coregoni and Daphnia galeata  mendotae.  Eubosmina  coregoni
was  found  in greatest numbers in the  western and Sandusky sub-basins,
Bosmina longirostris  reached highest concentrations in the  western  central
basin, and D. galeata mendotae was restricted to the  western central and
eastern  central  basins.

     By  the end  of October E.  coregoni,  B.  longirostris and Chydorus
sphaericus dominated the cladoceran community.  The seasonal  peak of
C. sphaericus was observed  during the late October cruise.   This species
was  found  in high concentrations in all but the western basin,  where it was
declining after a mid-August maximum.   Eubosmina coregoni  populations
were highest in the eastern central basin and  lowest  in  the western  ba-
sin In October.   Bosmina longirostris was found in highest numbers  in
the Sandusky sub-basin and western basin, with lower concentrations
observed in the central basin.

     Cladocerans  comprised  less than 10  percent of the total zooplankton
biomass (mg/m3) during early May.   By early September  they made up
over 55  percent of the zooplankton biomass  in all of the sub-basins  and
were of  greatest importance  in the western  and Sandusky sub-basins
where enriched  conditions seem to be most  favorable for their reproduction
and growth.

Copepods

     Patalas (1972) considered the differences  in the crustacean populations
of Lakes Superior,  Erie,  Huron and Ontario to be due to differences in
                                  284

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  1 x 10s _
  no./m   _
   1 x 10 _
  1 x 10 _
   1 x
                  AVERAGE CLADOCERAN CONCENTRATIONS
                  IN NO./m3 BY SUB-BASIN
MFTfj
                                             N
                           1974
Figure  110.   Average cladoceran concentrations in
                      by sub-basin.
                        285

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nutrient loading.  With increased nutrients,  a decrease in calanoid
copepods and  an increase in  cyclopoid copepods and cladocerans was
apparent.  According  to  McNaught (1975) this succession  may be better
explained by the fact that calanoid copepods  are nannoplankton feeders,
while many of the species most abundant in  eutrophic  waters are gen-
eralist feeders.  Therefore  animals such as  Bosmina  longirostris and
Eubosmina coregoni, which are able to utilize  a wide  range of particle
sizes, are better adapted to  the enriched conditions of the  central and
western basins  of Lake  Erie than  are the  diaptomids,  which utilize par-
ticles in the nannoplankton range.

    Gannon and Stemberger (1975) stated that in the oligotrophic off-
shore waters  of Lake Michigan calanoids made up 50 percent of the
total microcrustaceans.   But onshore  where  nutrient concentrations were
high, calanoids made  up  only five percent.

    In 1928 and 1929  Diaptomus was the most  abundant copepod in the
eastern half of  Lake Erie in July  (except for Limnocalanus located in
the deeper waters,  Wilson,  1960)  and in the  island region of the west-
ern basin in 1930 (Wright, 1955).   Since then, the Diaptomus copepods
have decreased in relative abundance, and Limnocalanus  has  nearly
disappeared (Gannon and  Beeton, 1971).   In  the central and western ba-
sins of  Lake  Erie the calanoids were  greatly outnumbered by the cyclo-
poids and cladocerans throughout the 1974 season,  and this trend was
also observed by Davis  (1969),  Patalas (1972), and Watson and Carpenter
(1974).

Lake Erie Western  and  Central Basin Copepods

    The  average copepod populations were small in early May,  peaking
in June and July and gradually declining from August through October
(Figure 111).   This general trend was apparent in  all four sub-basins.
The  copepods found  in the western and central basins  of  Lake Erie were
mainly cyclopoids.  Although calanoids at  times made up about 30 per-
cent of the  copepod  biomass, they were never  as numerous as the cyclo-
poids.  One harpactocoid copepod,  Canthocamptus  robertcokeri, was
found only in  low numbers early in the season in the  western portion  of
the lake.

    Of the cyclopoid copepods,  Cyclops  bicuspidatus thomasi  was  most
numerous during June and July, especially in the western basin and
Sandusky sub-basin.  This copepod  nearly disappeared from the western
and Sandusky sub-basins by August,  but remained common in the central
basin through October.   The Cyclops  vernal is population reached a peak
in early July  in the western  basin and outnumbered C. bicuspidatus
thomasi.  Cyclops vernal is was also abundant in the  Sandusky  sub-basin,

                                  286

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  no./m
  1 x 10
  1  x 10'
                   ttVERaGE COPEPOD CONCENTRATIONS
                   IN NO./m3 BY SUB-BASIN
A     M    J     J
                             1974
                                            *   WB

                                            •  SS B

                                            • WC B

                                            a 1C B
                                                N
Figure 111.   Average copepod concentrations in
               no./m3 by  sub-basin.
                         287

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 although It  was greatly outnumbered by C_.  bicuspidatus thomasi,  and
 was nearly excluded from  the  central basin throughout the sampling
 period.

      Mesocycloos  edax was abundant  in the central basin during the
 second  half of the summer,  with maximum populations observed in the
 eastern central basin in late August.  Mesocyclops edax was seldom
 collected  from the western portion of the lake.

      Tropocyclops prasinus var.  mexicanus  was found in relatively low
 numbers throughout the summer.  Its  highest  populations occurred  in
 September  and October with a maximum  in the eastern central basin
 during late  October.

      The most important calanoid copepods in 1974 were the  diaptomids:
 Diaptomus oregonensis, D^ siciloides, D_. ashlandii, D_.  minutis,  and
 D_.  sicilis.   During spring and early summer, D_. ashlandii  and D.
 siciloides were the most abundant calanoids  in the western basin~and
 the Sandusky sub-basin.  Diaptomus ashlandii  was also found in the
 western central basin and  was the only diaptomid common in the  central
 basin at this  time.   After  July,  few diaptomids were collected  in the
 western basin or  Sandusky sub-basin.   Diaptomus oregonensis was the
 most abundant calanoid  during  August and September and was  restricted
 to the central basin.   Diaptomus siciloides was a secondary compenent
 of the calanoid community  at this time and was also confined to the
 central  basin.

      Three other  calanoid copepods were found:   Limnocalanus macrurus
 in the western and western central  basins early  in the summer; Eury-
 temora  affinis in  the  western basin in early summer and in  the eastern
 central  basin in the fall; and Epischura lacustris  in  the Sandusky sub-
 basin in early June.  These copepods were never found in abundance.

      Immature copepods made up a significant portion of the  zooplankton
 community.   High numbers of  naupii were found  in June in the central
 basin and July in the  western and  Sandusky sub-basin.   During June and
 July the cyclopoid copepodid population was high,  with  the greatest  con-
 centrations  found  in the central basin.  Calanoid  copepodids  occurred in
relatively low concentrations in both  basins throughout the summer.

     Copepodid numbers were usually higher than  nauplii  numbers.   This
 would indicate that many nauplii  were lost through the  80-micron  mesh
 of the net.   When comparing levels of copepodids to adult copepods, it
 was  evident that  a large number of these immature forms did  not de-
 velop into adults, probably due to predation.
                                    288

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FUTURE  OBJECTIVES

    Further analyses and comparisons of 1974  and 1975 data are yet to
be completed.   Biomass values for the most frequently  encountered
microcrustacean species will be obtained directly  in the laboratory.  Dry
weight (mg/m3) may therefore be calculated more accurately than by
use of literature values alone.

    In 1966, Williams stated that numbers  of rotifers correlate directly
to phytoplankton abundance.   Glooschenko,  et al. (1974) did not consider
zooplankton numbers to be  in phase  with chlorophyll a_ or  pheopigments,
but claimed that the zooplankton food chain in Lake  Erie is chiefly
detrital and that living algae are  more important as food  in oligotrophic
lakes.  Patalas (1972) related crustacean abundance with degree of
trophy, especially particulate phosphorus loading rates.

    Attempts will  be made to investigate some of these reports by corre-
lating  zooplankton  biomass  and  community structure with parameters such
as temperature, chlorophyll, particulate carbon, particulate phosphorus,
particulate  nitrogen and turbidity.   Statistical analyses  will hopefully
provide insight into community  structure within the basins  and through-
out the season and also determine variability due  to sampling and count-
ing methods.

SUMMARY

    1.  Zooplankton samples collected from 51  western and central
        basin  stations during the May to November field season of
         1974 were analyzed to  determine species  composition and
        seasonal succession of rotifers, cladocerans and  copepods.

    2.   In  spite of their  small size, rotifers comprised a signifi-
         cant percentage of the  zooplankton biomass (6-40 percent
         in  the  western basin).   Numerical differences in  rotifer
         concentrations from basin to basin were quite dramatic.

    3.   During 1974,  high numbers  of cladocerans were observed
         in  both  basins, with early  summer and autumn pulses.
         Cladocerans  comprised the  highest percentage of  the
         zooplankton biomass during  the late summer and  fall.

    4.   Cyclopoid copepods were dominant over calanoid cope-
         pods throughout the  1974 field season.  The greatest
         numbers of copepods occurred during  June and July
         in  both basins, and numbers declined  steadily through
         the remainder of the sampling season.

                                  289

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          High numbers of rotifers occurred  during  1974 in  the
          western and central basins of Lake Erie,  and such
          high concentrations are  considered  indicative  of enriched
          conditions.  Cladoceran numbers have increased steadily
          since 1939, and this  group currently  has higher  concen-
          trations in the western basin of Lake Erie than else-
          where  in the Great Lakes.   Through  the years,  cladocerans
          and cyclopoid  copepods have gradually outnumbered the
          once dominant calanoid copepods.   The trend from a cala-
          noid-dominated to a cyclopoid and cladoceran-dominated
          community has been observed during  studies of other
          lakes which have undergone  nutrient enrichment.
REFERENCES

Ahlstrom,  E.H.   1934.   A quantitative study of Rotatoria  in Terwilliger's
    Pond,  Put-in-Bay, Ohio.  Ohio State  Univ.  Nat. Hist. Surv.  Bull.
    No.  30.   36 p.

Ahlstrom,  E.H.   1940.   A revision of the rotatorian genera Brachionus
    and  Platyias with descriptions  of one new species and  two new
    varieties.   Bull.  Am  Museum  Nat.  Hist.  77:143-184.

Ahlstrom,  E.H.   1943.   A revision of the rotatorian genus Keratella
    with descriptions  of three new species and five  new varieties.  Bull.
    Am. Museum Nat. Hist.  80:411-457.

Bradshaw,  A.S.  1964.   The crustacean zooplankton picture Lake Erie
    1939-49-59; Cayuga,  1910-51-61.   Verh. Internat.  Verein.  Limnol.
    XV:700-708.

Brooks,  J.L.   1957.  The systematics of North American Daphnia.  Mem.
    Conn.  Acad. Arts Sci.,  13:1-180.

Chandler,  D.C.  1940.   Limnological studies  of western Lake Erie. I.
    Plankton and certain physical-chemical data of the  Bass Islands
    Region,  from September, 1938 to November,  1939.  Ohio J.  Sci.
    40:291-336.

Davis, C.C.  1969.   Seasonal distribution,  constitution and  abundance of
    zooplankton in  Lake Erie.   J.  Fish. Res.  Bd. Can.   26(9):2459-2476.
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Deevey,  E.S. Jr.  and G.B.  Deevey.  1971.   The American species of
    Eubosmina Seligo (Crustacea, Cladocera).  Limnol.  and Oceanogr.
    16(2):201-218.

Dumont,  H.J., I.  Van de Velde and S.  Dumont.   1975.   The dry  weight
    estimate of biomass  in a selection of Cladocera,  Copepoda  and Roti-
    fera from the  plankton,  periphyton and  benthos of Continental waters.
    Oecologia (Berl.) 19,  p. 75-97.

Eddy,  S. and A.C. Hodson.   1961.  Taxonomic keys to the common  ani-
    mals of the north central states.  Burgess Publishing Co., Minnea-
    polis.   162 p.

Engel, R.A.  1962.   A quantitative study of the zooplankton in  the island
    region of western  Lake  Erie during  the summer  of 1961.   Ohio State
    Univ.  M. Sc. Thesis  41 p.

Gannon,  J.E. and A.M.  Beeton.   1971.  The decline of  the large zoo-
    plankter Limnocalanus macrurus (Copep.  Crust.) in  Lake Erie.
    Proc. 14th Conf. Great  Lakes Research.   1971:27-38.

Gannon,  J.E. and R.S.  Stemberger.   1975.   Rotifer and crustacean
    zooplankton species  composition and community structure as water
    quality indicators.   Symposium on Plankton and  periphyton as water
    quality indicators, 26th ann.   AIBS Meeting,  Corvalis,  Oregon.

Glooschenko,  W.A., J.E.  Moore,  and  R.A.  Vollenweider.   1974.  Spa-
    tial  and temporal distribution of chlorophyll a  and pheopigments in
    surface waters of Lake Erie.  J. Fish.  Res.  Bd.  Can. 31:265-274.

Hubschman,  J.H.   1960.  Relative daily abundance of planktonic crus-
    tacea  in the Island Region of western  Lake  Erie.  Ohio J. Sci.
    60:335-340.

Jahoda,  W.J.   1948.  Seasonal  differences in distribution of Diaptomus
    (Copepoda) in western Lake  Erie.   Ohio  State Univ.  Ph.  D.  Disser-
    tation.  96 p.

Jennings,  H.S.   19O1 .  Rotifera of the United States with  especial refer-
    ence to those of the Great  Lakes.   U.S. Fish Comm.  Bull.  22(2):
    273-352.
                                   291

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 Kellicott, D.S.  1896.   The Rotifera of  Sandusky Bay.   I.   Proc. Amer.
     Microscop. Soc.   18:155-164.

 Kellicott, D.S.  1897,   The Rotifera of  Sandusky Bay.  II.   Proc. Amer.
     Microscop. Soc.   19:43-54.

 Makarewicz, J.C.   1974.  The community oF zooplankton  and its produc-
     tion in  Mirror Lake.  Cornell Univ. Ph.  D. Dissertation.

 McNaught, D.C.  1975.  A hypothesis to  explain the succession From
     calanoids to cladocerans during eutrophication.  Verh. Internat. Verein.
     Limnol. 19:724-731.

 McNaught, D.C. M.  Buzzard and S.  Levine.   1975.   Zooplankton production
     in Lake  Ontario as  influenced by environmental perturbations. USEPA
     660/3-75-O21.   156 p.

 Nauwerck, A.   1963.  Translated by Barbara  J.  Logan.    The relation-
     ships between zooplankton and phytoplankton  in Lake  Erie.  Symbolae
     Botanicae Upsaliensis XVII:5.   16O p.

 Patalas,  K.   1972.  Crustacean plankton and  the  eutrophication oF St.
     Lawrence Great Lakes.  J. Fish. Res. Bd. Can.  29:1451-1462.

 Pennak, R.W.   1953.   Fresh-water invertebrates oF the  United States.
     Ronald Press,  N.Y.  769 p.

 Rolan,  R.G.,  N. Zack and  M.  Pritschau.   1973.  Zooplankton Crustacea
     of the Cleveland nearshore  area of Lake Erie  1971-1972.   Proc. 16th
     Conf.  Great Lakes Res. 1973:116-131.

 Ruttner-Kolisko, A.   1974.   Plankton rotifers, biology and taxonomy.
     E.  Schwerzerbart'sche  Verlagsbuchh andlung, Stuttgart.   146 p.

 Secoy,  D.M.  1962.   A survey of the planktonic rotifers of Fishery Bay,
     South Bass  Island, Lake Erie.   Ohio  State Univ.  M.  Sc.  Thesis.  24 p.

 Schindler, D.W. and B. Noven.  1971.  Vertical distribution  and seasonal
     abundance of zooplankton in two shallow lakes of the  Experimental
     Lakes Area, northwestern Ontario.  J.  Fish. Res.  Bd.  Can.  28:245-256.

Voight,  M.  1957.  Rotatoria.   Die Radertiere Mitteleuropas.  2  vols.
     Borntraeger, Berlin.
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Ward,  H.B.  and  G.C. Whipple.   1959.   Freshwater  biology.  2nd ed.
    W.T. Edmondson (ed.). John Wiley and Sons,  New York and
    London.   1248 p.

Watson,  N.H.F.   1976.   Seasonal distribution and  abundance of crusta-
    cean zooplankton in  Lake Erie, 1970.  J.  Fish.  Res. Bd.  Can.
    33:612-621.

Watson,  N.H.F.  and G.F.  Carpenter.  1974.  Seasonal  abundance of
    crustacean zooplankton  and net plankton biomass  of Lakes Huron,
    Erie and  Ontario.  J.  Fish.  Res. Bd. Can.   31:309-317.

Williams, L.G.   1966.  Planktonic rotifers of major waterways  of the
    United States.  Limnol. Oceanogr.,  11:83-91.

Wilson, C.B.  1960.  The  macroplankton of Lake  Erie.   in  Fish, C.J.
    Limnological  survey of eastern and central Lake Erie 1928-1929.
    U.S. Fish and Wildlife Serv. Spec.  Sci.  Rept.   Fisheries.  334:145-172,

Wilson, J.B. and J.C. Roff.  1973.  Seasonal vertical distribution and
    diurnal  migration  patterns of Lake  Ontario Crustacean zooplankton
    Proc.  16th Conf.  Great Lakes Res.  1973:190-203.

Wright, S.   1955.  Limnological survey of western  Lake Erie.  U.S.
    Fish and Wildlife  Serv. Spec. Sci. Rept.  Fisheries. No.  139.   341 p.
                                   293

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                              SECTION 10

        BENTHIC MACROIN VERTEBRATE DISTRIBUTIONS IN
       THE CENTRAL AND WESTERN  BASINS OF LAKE ERIE

                             N.W.  Britt
                       Department of Entymology
                       The Ohio State  University

                  A.J. Pliodzinskas and E.M.  Hair
                 Center for Lake  Erie Area Research
                       The Ohio State  University
 INTRODUCTION

     Lake Erie  has been a discussion topic for  a number of years due
to its status as a  polluted body of water.   Changes  in the lake's water
quality and its  biota have been noted throughout the  last century (Beeton,
 1961;  Brinkhurst et al., 1968; Britt, 1955; Britt et  al.,  1973;  Brown,
 1953;  Burns and Ross,  1972; Carr and  Hiltunen,  1965;  Federal Water
Pollution Control Administration,  1968; Herdendorf et al.,  1974;  Hiltunen,
1969;  Langlois,  1954; Shelford and  Boesel, 1942; Osburn, 1926; Wood,
1953  and 1963;  Wright,  1955).  In most cases,  the conclusions of their
studies indicated degradation  of Lake Erie's waters.

    Aspects of  water quality  degradation  involve:  1) increased sediment
loadings, 2) increased turbidities, 3) higher bacterial counts (particularly
of the coliform  bacteria), 4)  increase in the number and frequency of
nuisance algal blooms,  5) an increasingly  larger  area  of the bottom
becoming anoxic, 6) decreasing fish  populations,  7) shifts in the  bottom
fauna from sensitive forms  to tolerant forms,  and 8) Increased loading
and regeneration of major algal nutrients (particularly phosphorus and
nitrogen).   To  alleviate degradation,  both  the United States  and Canada
began to implement control  measures designed  to reduce the level of
waste and  nutrient inputs  into  Lake  Erie.   To  evaluate  the efficacy of
these measures  upon Lake Erie waters,  a multidisciplinary  approach
project was initiated by the Center for  Lake Erie Area Research (1974).
This  assessment consists of monitoring several physical, chemical and
biological components of the Lake Erie  ecosystem.   This particular
subproject was  designed to examine  Lake Erie's benthic macroinverte-
brate communities.               294

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METHODS

    Duplicate Ponar grab samples (0.555 m2) were taken at each of 52
stations in Lake Erie's western and central basins during  cruises  aboard
Ohio State University's research vessel, R/V Hydra.   During the  initial
stages of  the project several research vessels were used including:
R/V Dambach (Great Lakes Laboratory, SUNY),  R/V  Maple (Great Lakes
Research  Division, University of Michigan), and  P/B  Bluewater (Gross
lie  Laboratory, USEPA).

    Samples were taken during  ice-free months June  1973  through
December 1975 for a total of 15 benthological cruises (Table 71).   The
results of nine  cruises,  June 1973 through October 1974,  are discussed
here.

          TABLE 71.   SAMPLING PERIODS  FOR LAKE ERIE
               NUTRIENT STUDY - BENTHOS CRUISES

          Cruise Number               Date

              1                1973     28  June -  12 July
              2                         17  July - 23 July
              5                         29  August  - 4  September
              7                         14  October - 24 October
              2                1974     25  April - 4 May
              4                         1 June -  10 June
              6                        26 July -  4 August
              8                        26 August  - 7  September
             10                        21  October - 1  November
     The Ponar samples were taken with a power  winch and wet seived
on  board through a U.S.  Soil Series No.  49  screen.  The retained
material was washed  into plastic jars and  preserved.  The samples
initially were  preserved  with 10 percent formalin, but the  1975 samples
were preserved  with AGW (alcohol:glycerine:water in  a 7O:5:25 mixture).
The samples were then labeled and stored until analyzed.

     The stored samples  were stained with Rose Bengal solution and
sorted  into Oligochaeta and non-Oligochaeta fractions.   Non-ol igochaetes
were identified by Dr. N.W. Britt.  The oligochaetes were initially
identified by Dr. E.M. Hair and later by  A.J. Pliodzinskas.   Enumera-
tion and identification  proceeded simultaneously.
                                   295

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 ORGANISM DISTRIBUTION,  DENSITY AND DIVERSITY

     Organism distributions and  their abundances are the results of vari-
 ous interactions of the biotic and abiotic components of the environment.
 In  the open waters of Lake  Erie's western and  central  basins during the
 1973 and  1974 sampling seasons,  the  benthic macroinvertebrate fauna
 is  composed of  at least 66 taxa,  identified to species where possible.
 Thirty-six of these taxa are  found throughout both basins,  while eleven
 and nineteen are limited  to the  western and central basins, respectively
 (Tables  72 and 73).

     The  number of different  taxa per  square meter or  diversity found
 throughout the lake varies among  stations and with time (Table  74).
 Average  diversity of  samples (1973-1974) indicates that the lake bottom
 can be divided  into four general  zones of diversity (Figure  112).   The
 boundaries of these zones presented herein should not be considered
 absolute  as they are  interpretations of the combined  data.

     Zone  I,  areas of lowest  diversity, is to  be found:   1)  along the
 northeastern edge of  the  central  basin  (stations  28 and  29), 2) south of
 Pelee Point (station 50),  and 3) just west of  Fairport Harbor (station
 35).  The Zone  I stations were  the least successfully sampled stations
 during the 1973  and  1974 seasons due  primarily to substrate type and
 secondarily to adverse  weather conditions.  These stations  have either
 sand or  sand/gravel veneered clay substrates which reduce  the  effective-
 ness of the  Ponar sampler (Figure 113).  Generally, these  types  of sub-
 strates are  inhospitable to sedentary organisms due to the  grinding action
 of the sediments during current activity (Purdy,  1967,  Figure 114).  In
 addition,  sandy regions are  relatively  turbulent  and result  in little de-
 tritus settling out and remaining  in the sediments; subsequently, there
 is little  food resource available.   It is much more difficult for  small
 organisms to burrow  in sand than in mud because of the difference in
 particle  size and in the ability  of the organism  to make  cohesive  bur-
 rows in  each sediment  type.

     Zone II (4-7 taxa) lies  primarily within the  20-25-meter depth zone
(Figure 115)  and substrates  consisting  of soft,  silty, grey  mud  with the
 major fraction consisting  of  clay.   The Zone II  region  consists  of four
separate areas.  The largest area encompasses much of the south side
of the western half of the central  basin up to about midway  between
Cleveland  and Fairport  Harbor.   Two  other areas of Zone  II are  located
 in the eastern half of the central basin, one in the middle-eastern sec-
tion and  one  in the  north-central  section of the  sub-basin.   Along the
western edge of the lake is the fourth  Zone II region.   This area lies
 in depths of six  meters and has a substrate consisting of soft grey mud


                                    296

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   TABLE 72.  TAXANOMIC GROUPS FOUND IN  LAKE  ERIE'S
      WESTERN AND CENTRAL BASINS  DURING  LAKE  ERIE
                   NUTRIENT STUDY  (1973-1974)
ANNELIDA
  Hi rudinea
    Helobdella elongata
    E. stagnalis
    E. fusca
    Glossiphonia complanata
    G. heteroclita
    Erpobdella punatata
   Polychaeta
    tfanayunkia speciosa
   01igochaeta
    Aulodrilus americanus
    A. lirrmobius
    A. pluriseta
    Branchiura sowerbyi
    Ilyodrilus templetoni
    Lirmodrilus cervix
    L. cervix variant
    L. claperedeianus
    L. hoffmeisteri
    L. maianeensis
    L. spiralis
    L. udekemianus
    Peloscolex ferox
    P. multisetosus
    Potamotkrix moldaviensis
    P. vejdovskyi
    Tubifex  tubifex
    Ar-steonais lomondi
    Dero  digitata
    Nais  sp.
    Ophidonais serpentina
    Paranais foreli
    P.  longiseta
    P. menoni
    Stylaria lacustris
     Vejdovskyella intermedia
     Stylodrilus herringianus
ARTHROPODA
   Crustacea
     Asellus  r. racovitzai
     Garmarus fasciatus
     Pontoporeia affinis
     Mysis relecta
   Insecta
     Oecetis sp.
     Oecetis eddlistoni
     Chironomus plumosus
     C. riparius
     C. (Cryptochironomus)  sp.
     Coelotanypus sp.
     Metriocnemus sp.
     MicTOpsectra sp.
     Microtendipes sp.
     Procladius sp.
     Tanypus sp.
     Tanytarsus sp.
MOLLUSCA
 Gastropoda
     Physa sp.
     Heliosoma sp.
     Amnicola sp.
     Bulimus tentaculata
     Valvata sincera
     V. tricarinata
     Campeloma sp.
     Goniobasis sp.
     Somatogyra sp.
 Pelecypoda
     Ligumia recta
     Lampsilis radiata luteola
     Leptodea sp.
     Pisidiiari sp.
     Pisidium compression
     Sphaerium sp.
COELENTERATA
     Hydra sp.
PLATYHELMINTHES
     Planaridae
     Phabdocoela
                                  297

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                          TABLE 73.   BENTHIC  FAUNA FOUND IN LAKE  ERIE'S
                                     WESTERN  AND CENTRAL BASINS
vo
oo
Western  Basin

Oeaetie ep.
Oecetie eddliatoni
Helobdella fueoa
Glossiphonia heteroclita
G. aomplanata
HelioBoma ep .
Campeloma ep .
Lampsilie r. luteola
Leptodea ep.
Planaridae
LirmodriluB udekemianuB
 Central Basin

Tony tarBUB ep.
Micropnectra ep.
MetriccnemuB ep .
Miorotendipes ep .
Pontoporeia affinis
AulodriluB americanus
Ophidonais serpentina
Arcteonais lomondi
Paranaia foreli
P. menoni
Nais ep.
Stylaria laouetTiB
VejdovBkyella intermedia
Paranais longiaeta
Amphichaeta ep.
Stylodrilus herringianus
Manayunkia speaiosa
MyBie reliata
Hydra ep.
 Both  Basins

 Helobdella  stagnalis
 H.  elongata
 Erpobdella  punctata
 Chironomue  plumoeue
 C.  ripariue
 C.  (Cryptochironomus)  ep.
 Proeladiue  ep.
 Coelotanypus  ep.
 TanypuB ep .
 GanrnaruB faaiatus
 Asellus r.  raaovitzai
 Armicola ep.
 Valvata Bincera
 V.  tricarinata
 BulimuB tentaoulata
 Somatogyra  ep.
 Goniobasia  ep.
 Sphaerium ep.
 Pisidium ep.
 P. aompreBBwn
Rhabdoooela
 Physa ep.
Aulodrilus  lirmobius
A. pluriseta
Branchiura eowerbyi
LinmodriluB cervix
L. cervix variant
L. claperdeianus
L. hoffmeisteri
L. mawneensis
L. BpiraliB
Peloscolex ferox
P. multieetosuB
Potamothrix moldaviensis
P. vejdovskyi
Tubifex tubifex

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 TABLE 74.   BENTHIC MACROINVERTEBRATE DIVERSITY*
IN LAKE ERIE'S  WESTERN  AND CENTRAL  BASINS DURING
         LAKE  ERIE NUTRIENT STUDY (1973-1974)
Station Nuaber
23
24
?
2
5
I
27
28
29

^
}
1
32
33
!
<
3
4
'
\
A
5
6

&
J
40
41
1
4
4
2
3
•»
Cruiae Number
1 2' 5
17
J4
1
5
12
0
3
ll
q
12
11
13
7
13
15

I1?
12
12
4
6
^
45
46
47
•48
12
8

49 l*>
50
51
52
53
!
I
4
6
56
57
58
53
bO
61


>5
^
67
fa
2
1
12
13
13

23
13
19
11
17
17

14
7
in
16
7
12
1
9
2
1
11
14

13
10
13
8
12
14
13

13

8
7
in
4
IP
9
9
l
11
6
7
8

8
8
11
6
8
14

11
8
11
1
ll

•i
9
2

11
10
7


2
7
10
6
10
1
11
8
£
3
q

7

11

6
8
I
8

13
16
11


90

12
10
q
7
3

10

11


8
^
9
10
10

6
2
7
S

10
7
4

7
b

8
9

7
7
8
4
10
5
8
6
8
•^
1

6
"5
10
(a *
TO
71
10
5
8
9
72
73
;

1

i
B
r5
f8
3
laan
Stations Sanpled
}4

7


10
«3
8
a
6.


9
*3
3
8
8
5
12
5


8
39
4
2
6

8
5


7
38
2







12
6
9
13
12

11
9



8
6
6

11
5
8




7
11
8

11
11
5
11
14

11
1?
6
n
2
10


4
6

8

9
30
4

13





7
8
4
17
ll

7
7
9
12

b
4
4

9

7




1
b
5

7
4
4
6
2
12
f,

12
q

9


8
^
6
4
1
7
3«
6
ll
12





B
4
6
12
12

10
B
12
11
12
11
8
5


7
6

c

8
b

8

11

9
12
2
7
7
4
5
8

5


6
7
7
4

8
35
8







8
9
11
12
12

8
8
7
V


3
'}
14
10
4
9
7
10

6
7
15
16

16
11
14
11
11
IS
q
li
11
11




5
10
5
10
9
10
3t
10

17
10

12


9
9
7

11

&
7
12


8
7
4

8
9
7

9

9
5

7

13
11
ll
11
7
14

13
10
n

9


6
14

6

9
34
X
10
12
8
4
10
2
2
^
8
8
12
11
3
9
9
10
11
8
10
6
5
7
q
7
8
B
10
2
7
7
y
8
10
12
12
10
10
8
13
9
11
8
11
4
7
b
7
7
9
6
6
5
9

    *  Diversity is expressed as number of different
       taxa present/m .
                              299

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     KILOMETERS
                                               ZONE EZ[ 12-15 TAXA]
                                        £££% ZONE in [ 8-n]
                                        u*SS!j ZONEH[ 4-7J
                                        CTCC! ZONE I [ 0-3]

Figure  112.   Average benthic macro invertebrate  diversity
                (Taxa number/m2,   1973-1974).
                                             Post-glacial mud
                                             Soft mud «ith some sand
                                             Sand and/or gravel
                                             Glacial sediments, clay till
                                             vvith lag sand
                                             Bedrock, snaies in centra! basin
                                             and carbonates in  western ba^-n
                                                                   o
                                                          ml
                                                          o>l
Figure  113.   Distribution of surficial sediments.
                          300

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      40
                    40      80
              KILOMETERS
                                               f r~=  PROBABLE PREVAILING
                                                      BOTTOM FLOW
                                               Data Source: FWPCA, 1S68
          Figure 114.   Prevailing annual  bottom flow.
20    0   20  40  60  80
 I	1—I—I—I	1	'  i  i  i  '
       KILOMETERS
              Figure 115.   Lake Erie bathymetry.
                                 301

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with sand.  These nearshore  stations are at the mouth  of the Maumee
River,  near the  mouth of the Raisin River; at Locust Point; and  in the
western arm  of Catawba Island.

    Zone III (8-11 taxa)  extends  throughout most of the western basin
and along the margins of the  central basin.   The largest section  of Zone
III lies along the northern part of the central basin.  Depths  in Zone III
range  from a shallow eight meters  (station 60)  to the deepest station
(37) at 24  meters.  The zone  contains the greatest  variety  of substrates
ranging from rock through sand to  mud.

    Zone IV (12-15 taxa),  the zone of greatest  diversity, has two com-
ponents, one  at each  end of the study area.   Farther west  is the area
just east of the Detroit River  mouth and farther east is the area  from
just west of Ashtabula towards the  northeast (Figure 112).  The sediment
type in both regions is  identical,  i.e.,  soft,  grey,  silty mud with sand,

    A cursory examination of  Figure 112 would give an  incomplete assess-
ment  of macro invertebrate diversity.   Most of this  diversity is the re-
sult of the  presence of one major group, the  Oligochaeta (Figure  116).
The oligochaetes make up 40.9 percent of all taxa and numerically aver-
age 61.9 percent of all  individuals  (range:  20.2-96.1  percent).

    Organism abundance levels (density) are considered  to  indicate the
relative degree  of environmental  stress.  This  stress  is the frequency
with which  the physiological tolerance limits of an organism to some
environmental factor are exceeded (Menge and Sutherland,  1976).   Aver-
age density levels for the Lake Erie macro invertebrate fauna are divided
into two categories (2000-3000/m2 and 3000-4000/m2), both of which are
present in the Zone I diversity category.  If  greater abundance reflects
a lower stress environment for the species present, then the margins  of
the central  basin,  the mouth of the Detroit River,  and the  region just
lakeward of Sandusky Bay may be considered as more favorable environ-
ments than  other parts of the  lake  sampled (Figure 117).

    The high densities are due to the presence of large numbers  of
oligochaetes (Figures 118 and  119).  The two other faunal  components,
which  together with the  oligochaetes,  make up 92 percent,  numerically,
of all  the benthic macroinvertebrates are the  Chironomidae and the
Sphaeriidae.  Chironomid larvae  contribute 11.8 percent toward density
and Sphaeriids,  18.3 percent.  In terms of their contribution to diversity,
the chironomids  contribute 15.2 percent  and the sphaeriids, 4.5 percent.
Most  of the lake has  average chironomid densities up to 500/m2 with
scattered regions of higher density  (Figures  120 and 121).  Average
sphaeriid densities  indicate that there are two regions of low density,
the western basin and the northeastern corner of the central basin

                                   302

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           KILOMETERS
                                     L*f/2:3  ^'CO
Figure  116.   Average percent oligochaeta in the bottom  fauna.
          KILOMETERS
     i  4000-5000
       3000-4000
       2000-3000
cC'aj-J  1000-2000
          O-IOOO
Figure  117.   Average benthic macro invertebrate densities
              (indiv./m^) for central and  western basins  of
              Lake Erie 1973-1974.
                               303

-------
                                            0-IOOO/m2
                                  [II ]  IOOO-2000/m2
                                  [Ipllfij  2000-3000/m2
                                  ~_~r_"]  3000-4000/m2
                                         4000-5000/m2
Figure  118.   Average oligochaete  density for central
              and western  basins of Lake Erie  1973-1974.

Figure  119.   Average  percent oligochaetes in the  bottom
              fauna.
                          304

-------
                                                   0- 500/m2
                                                 500-lOOO/m*
                                              ni  IOOO-1500/m*
Figure  120.   Average chironomid density in central and western
              basins of Lake Erie  1973-1974.
              0     40
              •c
               KILOMETERS
        %
L:;:"J  o-io
V&M  "1-20

••  31-40
Figure  121.   Average  percent  of  chironomidae in the bottom fauna.
                                 305

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(Figures 122 and 123).  Likewise most  of the central basin has shaperiid
densities in the 500-1000/m2 range  with scattered  regions  of  higher  den-
sity.

     When the  overall diversity is separated into  its component groups,
the diversities within each  component may  be examined and the distribu-
 ions of each  individual taxa may be studies.  Oligochaete  diversity
varies throughout the lake bottom,  but most of the lake bottom  has from
five to  eight oligochaete species (Figure 124).  When  referring  to  oligo-
chaetes  in this paper we  are,  for all intents, referring to the Tibifici-
dae,  although  both the Lumbriculidae and the  Naididae are represented
(infrequently).

     The most important tubificid group  is the genus  Limnodrilus,  in
which there  are seven species.   The most ubiquitous  is L. hoffmeis.teri
and  in order of decreasing  distribution they are:   L_.  cervix,  L. cervix
variant, L.  maumeensis, L.  claperedeianus,  L_.  sprialis,  and~L.  udeke-
mianus  (Figure 125).

     In the western  basin, the  Limnodrilus  species  are the dominant
oligochaetes.  In the central basin,  Peloscolex ferox and P. multiseto-
sus  become  dominant.  P_.  ferox oftentimes is the  only oligochaete in
some of the stations.  Both Peloscolex  species are widely distributed
throughout the central basin and in large areas of the western basin
(Figure  126).

     Relative to these two genera,  the other oligochaete species  are
much less important, except locally, and less broadly distributed.
Branchiura sowerbyi  seems to be limited to the western basin and  to
the southwestern corner  of  the  central basin (Figure 126).   However,
it  has been collected at one site along the  north  central basin margin.

     Other tubificids,  including Potamothrix moldaviensis,  P. vejdovskyi,
Tubifex tubifex,  Ilyodrilus templetoni, Aulodrilus americanus, A.
Limnobius, and  A.  pluriseta are scattered  throughout both basins as
are the Naididae (Figure  127).

     Potamothrix moldaviensis seems to  be  found  along the  northern and
southern central basin margins.  Potamothrix vejdovskyi,  however, is
found in a number of areas.  It is very  probable that the  distribution
of these two species  is much more  widespread.   Tubifex tubifex is
found scattered along the  margins of both basins,  but is probably found
throughout the western basin and the western half of the central basin
(Figure 127).  Ilyodrilus  templetoni  has been found only off the  tip of
Pelee Point.   Aulodrilus  americanus and A. limnobius are found in both
basins, but so far have been  collected from only three stations  (Figure

                                   3Q6

-------
 20
20   40  60  80
 i'ii—I	1—I
        KILOMETERS
                                           JQlUIUfll    0- 500/m2
                                           r--n  500-IOOO/m2
                                           EiMi3  IOOO-1500/m2
                                           ^~~J  1500-2000/m2
                                           •••  2000-2 500/ m2
Figure  122.   Average sphaeriid density in the central and  western
              basins of Lake Erie  1973-1974.
               0      40
               •>—
               KILOMETERS
                            80
 Figure  123.  Average percent  of  sphaeridae in the bottom  fauna.
                                 307

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                      20
Co
O
CO
                                                                     0-4TAXA
                                                                     5-8 TAXA
                                                                     9-13 TAXA
Figure  124.
                                    Average oligochaete diversity in  the  central and
                                   western  basins of Lake Erie  1973 -  1974.

-------
                 O.)u. hoffnwisteri
CO
o
                                                            f.)L. spirolis

                                                              L. udakemianus
                                                                 (x)
                Figure  125.   Distribution of Limnodrilus  species  in  the central and western

                               basins of Lake Erie 1973-1974.

-------
                  Q.) Peloscolex ferox
                               d.) Stylodrilus

                                 herringianus
                   b.) Peloscolex
                      multisetosus
oo
i—«
o
                   C.) Bronchiura
                      sowerbyi
                 Figure 126.
Distribution of  Oligochaete species  in the  central  and  western

basins of  Lake  Erie  1973-1974.

-------
OJ
                  0.) Potamothrix moldoviensij
(j.) • Ilyodrilus templetoni
   + Audrilus
     omericanus
   a A. I imnobi
                   Figure  127.   Distribution of Qligochaete species in the central and western
                                   basins  of Lake  Erie  1973-1974.

-------
 127).  Aulodrilus pluriseta has been found  in three regions of the central
 basin (Figure  127).

      The lumbriculid, Stylodrilus herringianus. generally considered to
 be intolerant of enriched  conditions, is limited to the  far  east and  mid-
 dle region of the  central  basin (Figure 126).

     Brinkhurst el al. (1968) divided the oligochaetes of Lake Erie into
 three associations which approximated  the three basins.   They reported
 that the  oligochaetes were very abundant  at river mouths and in the
 western  basin  with Limnodrilus hoffmeisteri being the  most abundant
 species.  Found  with L_.  hoffmeisteri were other Limnodrilus species
 (L- claperedeianus.  L_.  cervix,  and L^ maumeensis).  Tubifex tubifex
 was found only at the Detroit river mouth.   Further out into  the western
 basin,  they  found  Aulodrilus and Potamothrix species together with
 Branchiura  sowerbyj^ and  Peloscolex ferox or multisetosus.  The central
 basin  had Fj, ferox as its  most abundant  oligochaete.   In addition Both-
 rioneurum vejdovskyanum. Ilyodrilus templetoni,  Potamothrix. and"^uTo-
 drllus sPecies  were found.  Aulodrilus  species  were widely distributed"
 and of greatest abundance  in the shallower  regions of the eastern basin.

     The  next most important faunal component is the  Mollusca,  repre-
 sented  by 16 taxa, of which the Sphaeriidae are the  most  important.
 The shpaeriids are distributed ubiquitously throughout both basins with
 the density  pattern described earlier.  The Unionidae are  limited to the
 open waters of the western basin  and occur in relatively low  numbers.
 The Gastropoda contribute  the most toward  mollusc diversity  with nine
 taxa.  Most of these snails, however,  are limited to the  western basin
 and the  southern  margin of the central  basin (Figure 128).  Valvata
 sincera  is the  most widely distributed  snail.  It occurs throughout both
 basins but doesn't occur in the middle  reaches of the central  basin
 (Figure  128).   The distribution of V_. sincera represents the maximum
 distribution  of  all  the Gastropoda.

    The gastropod distribution in  Lake  Erie is most  probably due to
 oxygen  processes  in the lake.  The snails collected were  almost exclu-
 sively prosobranch (internal gill) types  which must utilize dissolved
 oxygen  in the water for respiration.  Although  these organisms can  be
 found at oxygen concentrations as  low as 2 ppm (Hart and  Fuller, 1974)
 a complete  lack of oxygen for such time periods as in  the  Lake  Erie
central  basin during summer is prohibitive.  During the mixed well-
 oxygenated part of the year, there appears to very little  immigration to
these areas.  Valvata sincera seems to be the only snail which  has an
 extended  range  well  into the central basin, but it  too is not found in the
 middle reaches of  the central basin.  Snail  abundance levels in the  central
 basin are very  low (10-20/m2).

                                   312

-------
                 Q.) Sphoeriidae
to
I—"
oo
                 Figure 128.   Distribution of mollusca  in the central and western basins of

                               Lake Erie 1973-1974.

-------
     Untonid  clams are  likewise limited in their distribution.  This study
 found their abundance to be very  low in the  open  waters (1  or 2/m^)
 when collected.   However, the  frequency with  which they were collected
 was very low (maximum of 4 stations/cruise - usually 2  stations/cruise).
 The distribution of the  unionids and  their abundance  is probably due to
 several  factors; the  most important  of  which are  probably dissolved
 oxygen  and siltation  (which may occur synergistically).

     Following the Mollusca in importance are  the Chironomidae with  10
 taxa.  The density levels of the chironomids have been examined  earlier
 and  will not be discussed here.   The most common  chironomid is
 Chironomus  plumosus,  and in order  of decreasing distribution they are:
 Procladius sp.,  Chironomus  riparius,  Micropsectra  sp.,  Coelotanypus
 sp., Chironomus (Cryptochironomus) sp.,  Microtendipes sp., Metrioc-
 nemus sp.,  and Tanytarsus sp. (Figure 129).

     Throughout both  basins C_.  plumosus and Procladius  sp.  are the dom-
 inant chironomids.   In  the western basin,  Coelotanypus sp. and C.
 (Cryptochironomus) sp.  are significant  members  of the chironomld" as-
 semblage.  In the central basin these two  genera become insignificant
 except near  the basin margins.   Coelotanypus  sp.  is represented  along
 the southwestern  edge of the central  basin and C_.  (Cryptochironomus)
 sp., along the northwestern margin  of the central  basin  and  the southern
 margin  off Fairport  Harbor and Conneaut (Figure 129).

     Along the northern  shore, Micropsectra  sp.  and Tanytarsus sp. are
 well distributed (Figure 129).   Rare  or uncommon genera include Micro-
tendipes sp., Tanypus sp., and Metriocnemus  sp., which are found along
the margins  of  the central basin (Figure 129).

     The distributions of the various  taxa comprising relatively minor
 positions in the benthic  fauna are shown in Figure 130.  These  faunal
units contribute 15 taxa toward  diversity, but only eight  percent numer-
 ically toward density.   These fauna  include the six  leech  species,  two
amphipod species, one  isopod species,  one opposum  shrimp species,
one  polychaete species,  one coelenterate, two  flatworm families,  and
one  genera of caddisfly.

     High sediment organic content in bodies  of water,  such as Lake
 Erie (Figure 131) are accompanied by  a high oxygen demand by these
sediments and their  microflora.   In  shallow  waters this demand may  be
 met  at the mud-water interface  by water containing dissolved  oxygen
being driven downwards by wind action.  The dissolved oxygen content
of the bottom water  at the interface, however, will be lowered.   In
waters deep  enough to develop a summer hypolimnion, wind circulation
                                   314

-------
    0.) Chironomus
      plumosus
     C.) Coelotanypus sp
                                                  f.) Chironomus (Cryptochironomu s)

                                                     Tanytarsus sp
                         -t- Mlcrotendipes  sp

                         a Metrlocnemus  sp
Figure  129.
Distribution of  chlronomldae  In the  central  and  western  basins of

Lake Erie  1973-1974.

-------
oo
                 0.) Hirudinea
                                                             f.) + Manoyunkia speciosa
                                                               • Mysis relicta
               Figure  13O.   Distribution of minor elements in the central and  western basins
                               of  Lake  Erie  1973-1974.

-------
Figure 131.   Distribution of organic carbon  in  surficial
               sediments (%  dry  weight).
                                             BOTTOM DISSOLVED OXYGEN
                                            CRUISES  AUG29-SEPT4.I97
                                              Contour tntorvol: 2 PP">
Figure  132.   Bottom dissolved  oxygen,  cruise  5, August 29-
                September  4, 1973.
                           317

-------
is insufficient to  renew the hypolimnetic oxygen  stock.   As a result,
unless some  other mechanism operates, the hypolimnion may become
anoxic.   For the hypolimnion to become anoxic during the summer,
it must be  relatively thin and  have a sufficient oxygen depletion rate
as in the case  in Lake Erie's central  basin (Blanton and Winklhofer,
1972).  Thermal  stratification may persist  in  Lake Erie for up to  110
days,  which is sufficient  for anoxia  to  develop (Dobson and Gilbertso"^,
1972).

     During  summer  stratification the dissolved oxygen content of the
bottom waters becomes critical for the bottom fauna.  Only the faunal
elements  tolerant of low oxygen levels  or complete anoxia for relatively
long time periods can survive.  Faunal groups generally found  under
these conditions are the tubifid oligochaetes,  the sphaeriid clams,  and
the midge larvae (particularly those of Chironomus sp.).  These are
the major faunal  elements of Lake  Erie's central basin.

     The survival of  these organisms and  their relative success  in  areas
exhibiting anoxic  conditions is due at least  in  part to the ability of these
organisms to shift their metabolism from aerobic respiration to anaero-
bic respiration.   Anaerobic respiration involves obtaining energy by
splitting carbohydrates  into lactic acid, fatty acids  or mixtures of  the
two.  The process stops  at this point.  Aerobic  respiration is  similar
except that  the splitting of the carbohydrates is  carried  further to  pro-
duce carbon dioxide  and water.

     In 1973 the central basin was  anoxic  to its greatest extent  by late
August (Figure 132).   At this  time the average bottom fauna density
for the central basin was 3235/m2 with an  average diversity of seven.
These  values were the lowest  for the  1973  sampling year.  Prior to
this  time the central basin densities averaged 4120 and 5457/m2
during June  and July 1973, while diversities were  10 and 9 for the
same period (Table 75) .  As the season progressed towards anoxia in
the central  basin, changes in both density and diversity  were noted
(Figures  133  and 134).   Upon  the return of oxic  conditions  there was
also an increase  in the average density but no change in the diversity
for the 1973 year.

     In 1974,  the  bottom went anoxic in the southwestern edge of the
central basin at stations 51 and 46 about  12 August, while maximum
anoxia extent was reached about 26 August  (Figures 135  and 136).
Lowered  benthic densities were observed  for the 26 August-7 September
cruise.   In the central  basin density levels as well as diversity levels
dropped significantly  in June (Figures  133 and 134).  Recovery occurred
during July but dropped during  anoxia.  June  is the month when a  large
emergence of midges occurs,  and  this  may be the primary cause for
the density  and diversity  drop.
                                  318

-------
                       TABLE 75.  COMPARISON  OF  DENSITY AND  DIVERSITY

                            (TAXA NUMBER/M2) FOR  THE WESTERN AND

                                    CENTRAL  BASINS, 1973 - 1974
U)
i—>
UD

Cruise Number
Average Density
Central Basin
Western Basin
Central and
Western Average

Average Diversity
Central Basin
Western Basin
Central and
Western Average

1973
1
4120
5460
4494

1O
13
1O

2
5457
3805
5551

9
9
9

5
3225
3615
3323

7
11
8

7
3669
2337
3248

7
6
7

1974
2
4338
1618
3250

9
10
9

4
1865
674
4480

7
7
7

6
391O
1443
3135

9
7
8

8
3471
2592
3202

9
1O
10

10
3409
2017
3000

9
12
9


-------
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                                                                            a
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                                                          (f
                                                                                                          DENSITY (IND/Mf)X 10s

-------
                                                 FIGURE  24
                                               BOTTOM DSSOLVED OXYGEM
                                              CRUSE? 4U8UST 12-19, !S7«
                                                Ccntoi* Mtrvot: I ppm
Figure  135.   Bottom dissolved  oxygen,  cruise  7,
                August  12-19,  1974.
                                                FIGURE 25
                                               BOTTOM OSSOLVEO OxrSEN
                                              CRUISE 8 AUG 26- SEPT. 7, IS74
                                                Contour Inntvoll
Figure  136.
Bottom dissolved  oxygen,  cruise 8,
August 26-September  7,  1974.
                             321

-------
 HISTORICAL TRENDS

     The open  water fauna of Lake Erie  has definitely  undergone a num-
 ber of changes since at least  1930.   Prior to and during the 1930's, the
 bottom fauna of the  western basin was dominated by the burrowing may-
 fly, Hexagenia (Carr and Hiltunen,  1965; Chandler,  1963; Shelford and
 Boesel, 1942, Wright,  1955).   Data for  the central  basin bottom fauna
 was not available for this time period.  Other  taxanomic groups were
 relatively  unimportant in comparison,  although  the tubificid oligochaetes
 became very important in river mouths  and harbors (Table 76).  Wright
 (1955) categorized the western  basin into several pollution categories
 based  upon the number of tubificid oligochaetes present.  This  was an
 arbitrary scale which  seemed  proper for the time in the western basin.
 Light  pollution  was at oligochaete densities of 1OO to 999/m2.  Moderate
 pollution was at densities  10OO-5OOO/m2.  Heavy  pollution was at oligo-
 chaete densities greater than 5000/m2.  Most of  the western basin at
 this time was  considered unpolluted, while  the  mouths of the Maumee,
 Raisin and  Detroit Rivers were considered  polluted (Figure 137).

     From  1930 through 1961,  Carr and  Hiltunen (1965) reported that:
 (1) Hexagenia had decreased to less  than one percent of its  previous
 abundance,  (2)  oligochaetes had increased ninefold in density, (3) the
 extent of areas defined as polluted by  Wright/s index had increased,
 (4) chironomid  densities had increased four times, (5) sphaeriid levels
 had  magnified  twice,  and (6) the snail  densities increased sixfold.

     Britt (1955) reported a drastic decline  in the mayfly population dur-
 ing 1953 due to thermal stratification and bottom  water oxygen  depletion
 in the  western  basin.   The population  recovered by by  1959  had been
very much  reduced  (Beeton, 1961).   By  1965, Britt  et  al. (1973) con-
 sidered Hexagenia almost extinct  in the  western basin.   In  1973 and
 1974 no Hexagenia was collected.  In the spring,  summer and fall
of 1963 and  1964, the  U.S.  Public Health Service conducted  surveys
of the  bottom fauna of Lake Erie (FWPCA,  1968).  This survey was
also conducted  in 1967  and  1968.   They  concluded that  most of the
western and central  basins  were characterized by a  lack of the pollution
sensitive scud  populations  and  a preponderance  of pollution tolerant
species of sludgeworms,  bloodworms,  fingernail clams and  nematodes
(Figure 138).  They identified  34 species in the lake.   The survey
conducted during the 1963-1964 seasons  indicated  that the average bot-
tom  fauna  density was 1666/m2.  Average densities  for the western  and
central basins  were  1164 and 1861/m2,  respectively  (Figure 139).

    The 1973 and 1974 sampling seasons discussed here indicate
average bottom faunal  densities to be 3409/m2.  Average densities
for the western and central basins are 2612 and 3719/m2, respectively,
double the  levels  found in  1963 and  1964 (Figure 140).
                                  322

-------
                     TABLE  76.
LAKE ERIE WESTERN BASIN  BOTTOM FAUNA

    1929-1930 -  WRIGHT  (1955)
u>
i\i
U)

Amnlcola
Blthynta
Chlronomtdaa
Gastropoda
Qonlobnsla
Hexagenla
Hlrudlnea
Sphaerllda*
Trtchoptera
Tublflcldne
Valvata
laland Region
1929 1930
11

56


2U3
24
23
18
12
9
21

21


610
14
14
1
5
1
Maumae Bay - Toledo Harbor
1 929 1 930
50
31
15O


22
59
107
72
31
100
14
5
98


03
70
332
0
504
16
Portage
1929


18


0



19

River Area
193O


?


few



0

                               Detroit Rtver

                               1930
               Raisin River Section

               192Q     1930
Amnlcola
Blthynla
Chlronomldae
Gastropoda
Gonlobaala
Hexaganla
HlrucJlnoa
Sphaerlldae
Trlchoptera
TubiflcUlae
Valvnta


9
ei

0

374

1500

10

107

1H
57
7
125
70
i!1
4
88

55

18
0
3
46
0
1 04
1












-------
                                  Eastern Limits of
                                  Study Ar«a
              loin

       [ '"~J I I(£AVY FfJI .1.1 ITION
Figure  137.   Extent of  organic pollution  Indicated by tublflcld Index
                (Wright,  1955).

-------
ro
                            20    0   20  40   60  80
                            		I	1—I	1—I
                                    KILOMETERS
                                    Data Source:  FWPCA, 1S68
        PONTOPOREIA AFFINIS
        PLUS OTHER AMPHIPODA


        TUBIFICIOAE      ISOPODA


U;UJ:-:^:- NEMATODA
                                                                                                PROSOBRANCHIA
                                                                                 TUBIFICIOAE
                                                                                 TENDIPEDIOAE
                                                                                 SPHAERIIDE
                                                                                 NEMATODA
                                                                                 INSUFFICIENT
                                                                                 SAMPLING
                     ONLY
                          Figure  138.    Lake  Erie  benthic  population distribution  1963-1964,

-------
                                                                                 JI777
                                                                              .1067
   20
            20
      40  60  80
       I - 1 — I - i—l
           KILOMETERS
           542
5749-
        ^847
                 146*
            • 1086     «I097

             •913

^
•91
• 369
• 8
• 443

«7Ofi

\
• 3544
• 574
.1073
•1056

• 926
/295»
CU •
^=
•991
• ISO
.1001 .£
• 860
.4934

*805
__ .3675
.1741
'97S9*332 .1036
•944 »806 S
864*"67>^7
556,-^
/^
^
• 772 '
• 437
1310. /
6.63^
r




                                        • 331
                                                 • 2623
                                                     1717
    61* 2391
     • 787
            •1096
                        •454
                                         • 345
                                               483*
                  .12543
             434 »5262
    • 216
       1883
145*

• 64
• 2833
 • 3725
               • 809
     Figure 139.
                    • 665
                          • 762
                          • 459
          •788

          •163
                        • 348

                        • 694
                                                Data Source:  FWPCA, 1S68
            Lake Erie  benthic population  distribution
            1963-1964.
                                                  Density = lndividuals/rr2
     Figure 140.
           Average  density Lake  Erie benthic populations
           1963-1964.
                                       326

-------
    If Wright's (1955)  pollution index utilizing  the  oligochaetes was
applied to  the  1973 and 1974 field  data,  almost all of the western and
central basin would be considered  moderately  polluted.   This index,
however,  is an arbitrary one and  caution should be applied in placing
absolute faith in it.

CONCLUSIONS

    Lake Erie's bottom  fauna  has  changed since 1930.   During the per-
iod prior to 1953, the western basin bottom fauna was  dominated  by  the
burrowing  mayfly, Hexagenia sp.  Tubificid  oligochaetes were insignifi-
cant members of the  fauna except  near river  mouths and harbors.  Cui
rently Hexagenia  is considered extinct in the western basin.  Greater
than 61 percent of the bottom  fauna  is dominated primarily by the tubi-
ficid  oligochaetes of the genus  Limnodrilus.    Chironomid larvae comprise
the next most  abundant group with less than 20 percent of the bottom
fauna.  The sphaeriid  clams make up less than  10 percent of the bottom
fauna, except near the  Detroit  River where  they comprise 11 to 20  pel—
cent of the bottom fauna.

    The central  basin fauna is likewise  dominated by oligochaetes.   The
dominant  oligochaete is  Peloscolex ferox.   However, tubificids of the
genus Limnodrilus frequently make up significant components of the
fauna and  are  especially  important along the northern  shore (11  to 30
percent of the bottom  fauna).   The sphaeriid clams are major components
throughout the central basin,  and  in many cases are co-dominant  with
the oligochaetes.   The  sphaeriid clams  comprise  from 21  to 50 percent
of the bottom fauna.

    Eight  percent of the  bottom fauna, numerically, is comprised of
the 15  "minor" taxa.  These include leeches, amphipods,  isopods, poly-
chaete worms,  mysids,  coelenterates,  flatworms, and  caddisflies.
Most of the numerical contributions  of these taxa  is due to the aquatic
isopod, Asellus  racovitzai racovitzai.

    If Wright's (1955) pollution  index is applied  to the  1973-1974  sam-
pling period, most of the study area would  be considered  moderately
polluted.   Caution must be exercised in trusting this index.  The
average density  of the bottom  fauna  has doubled since the USPHS 1963-
1964  survey with most of this  change due to increases in  oligochaete
density.
                                    327

-------
REFERENCES

 Beeton,  A.M.  1961.  Environmental  changes in  Lake Erie.  Trans.
      Am.  Fish. Soc.  90(2): 1 53-159.

 Blanton, J.O. and R.S. Winklhoffer.  1972.  Physical processes affecting
      the hypoHmnion of the central  basin of Lake  Erie.   Pages 9-38  in
      Project  Hypo, N.Burns and C. Ross (eds.).  CCIW  Paper No. 6~T~
      USEPA  Tech. Rept.  TS-05-71-208-24.  182  p.

 Brinkhurst, R.O., A. L.  Hamilton, and H.B. Herrington.  1968.  Com-
      ponents  of the bottom fauna of the  Great Lakes.  Univ. Toronto.
      Great Lakes  Inst. PR 33.  49 p.

 Britt, N.W.  1955.  Stratification in  western Lake Erie  in summer  1953:
      effects on the Hexegenia (Ephemeroptera) population.   Ecology
      36(2):239-244.

 Britt, N.W.,  J.T. Addis  and R.  Engel.  1973.   Limnological  studies
      of the island  area of western Lake Erie.  Bull. Ohio Biol. Surv.
      4(3): 1-89.

 Brown, E.H.   1953.   Survey of the bottom fauna  at the mouths of ten
      Lake Erie south shore rivers:  its abundance, composition, and
      use as an index of stream  pollution.   Ohio Dept. Nat. Res.,  Div.
      Water, Lake  Erie Poll. Surv.  Final Rept.  p. 156-170.

 Burns,  N. and C.  Ross (eds.).   1972.  Project Hypo.  CCIW  Paper No.
      6.  USEPA Tech. Rept.  TS-05-71-208-24.   182 p.

 Carr, J.F. and J.K.  Hiltunen.  1965.   Changes  in the bottom fauna of
      western  Lake Erie from  1930 to  1961.   Limnol. Oceanogr. 1O(4)
      55-1 -569.

 Center for  Lake  Erie Area Research.   1974.   Lake  Erie  nutrient control
      program: an assessment of its  effectiveness in  controlling  lake
      eutrophication.  Prog.  Rept.  1973 Field  Season.   The Ohio State
      Univ.  129 p.

 Chandler,  D.C.  1963.  Burrowing mayfly nymphs in western Lake Erie
      previous to 1947.  Proc. 6th Conf. Great  Lakes Res.,  Univ.  Mich.
      Great Lakes Res. Div. Pub.  10:267-268.
                                 328

-------
 Dobson, H.H.  and M.  Gilbertson.  1972.  Oxygen depletion in the hypo-
       limnion of the central basin  of Lake Erie 1929 to 1970.   Pages 3-
       8 In Project Hypo, N.  Burns and C.  Ross (eds.).   CCIW Paper
       No~7~6, USEPA Tech. Rept.  TS-05-71-2O8-24.  182 p.

Federal Water Pollution Control Administration.   1968.   Lake Erie
       Environmental Survey 1963-1964.  U.S.  Dept. Interior FWPCA
       Great Lakes Region 1968.  170 p.

Federal Water Pollution Control Administration.   1968.   Lake Erie
       Surveilance Data Summary 1967-1968.  U.S. Dept. Interior
       FWPCA Great Lakes  Region  1968.   Cleveland Program Office.
       65 p.

Hart, C.W.,  Jr. and  S.L.  Fuller, (eds.)-  1974.   Pollution ecology of
       freshwater invertebrates.  Academic Press,  N.Y.  389 p.

Herdendorf, C.E.,  S.M.  Hartley,  and  L.J.  Charlesworth.   1974.   Lake
       Erie bibliography in environmental Sciences.   Bull. Ohio Biol.
       Surv.  5(5):119.

Hiltunen,  J.K.  1969.   Distribution of Oligochaetes in western Lake
       Erie 1961.   Limnol.    Oceanogr.   14(2):260-264.

Langlois, T.H.   1954.  The western end of  Lake Erie and its ecology
       J. Edwards Publ. Co.   Ann Arbor,  Mich.  479 p.

Menge, B.A.  and J.P.  Sutherland.   1976.   Species diversity gradients:
       synthesis of the  roles of predation, competition and temporal
       heterogeneity.  Am.  Nat. 110(973):351-369.

Osburn,  R.C.  1926.   A preliminary study of the extent  and Distribution
       of sewage pollution in the west end of Lake Erie.   Unpublished
       report to Ohio State  Fish and Game Division, (manuscript availa-
       ble at  F.T.  Stone Laboratory,  Ohio State University,  Put-in-Bay,
       Ohio).   p. 238-271.

Purdy, E.G.   1964.  "Sediments as  substrates"  in Approaches to
       Paleoecology. J.  Lumbrie and N.  Newall.  1964.  John  Wiley
       and  Sons,  N.Y.   432 p.

Shelford, V.E. and M.W.  Bosel.  1942.  Bottom animal  communities
       of the  Island  area of western Lake Erie in  the summer of  1937.
       Ohio J. Sci .  43(5): 179-190.
                                  329

-------
Thomas,  R.L., J.M. Jaquet, L.A.  Kemp and C.F.  Lewis.  1976.
      Surficial sediments of Lake Erie.   J.  Fish.  Res. Bd.  Can.
      33(3):395-403.

Wood, K.G.  1953.  Distribution and ecology of certain bottom living
      Invertebrates of the western basin of Lake Erie.   Ohio State
      Univ.  Ph.D.  Dissertation.   72 p.

Wood, K.G.  1963.  The bottom fauna of western Lake Erie.  1951-
      1952.   Proc. 6th Conf. on Great Lakes Res. Univ. Mich.   Great
      Lakes Res. Div.  Pub.

Wright, S.   1955.   Limnological  survey of western Lake Erie.   U.S.
      Fish and Wildlife Serv., Spec.  Sci. Rept. Fisheries No. 139
      341  p.
                                 330

-------
                                SECTION 11

              STATISTICAL ANALYSIS OF THE  1975  INTER-
                   COMPARISON  STUDY  ON  LAKE ERIE

                               Paul I.  Feder
                          Department of Statistics
                         The  Ohio State University

                            John E. Zapotosky
                    Center for Lake  Erie Area Research
                         The  Ohio State University
INTRODUCTION

      In recent years a number of laboratories and government agencies
have maintained  extensive environmental monitoring programs on the
Great Lakes.  As  part of these efforts, the  Canada Centre for Inland
Waters  (CCIW),  the  Great  Lakes  Laboratory (GLL) of the  State Univer-
sity  of New York at Buffalo  and the  Center for Lake  Erie  Area Research
(CLEAR)  at The Ohio  State  University have ongoing monitoring programs
on Lake Erie.  As in the IFYGL intercomparisons (Robertson,  Elder and
Davies,  1974) this study attempts to assess the differences that arise
between these organizations  due to sampling  and subsequent analysis, to
determine the feasibility of combining  past and  future data obtained by
the laboratories.

      On  10 June 1975 a number of physical,  chemical and biological
parameters were taken at two stations four miles  northeast of Conneaut,
Ohio.  This report discusses the statistical  results of a split  sample
analysis on six chemical properties  of the water;  in particular, the
results  for the  measures of  soluble  reactive phosphorus  (SRP), total
phosphorus (TP), total soluble phosphorus (TSP),  nitrate plus  nitrite
(N+N),  ammonia (NH3) and total reactive silicate (SiOg)  are considered.

BACKGROUND

      Three  research  groups are presently monitoring physical, chemical
and  biological  parameters  in Lake Erie.  These groups  are the Canada
Centre  for Inland Waters (R/V Northern Seal), Great Lakes Laboratory,
                                   331

-------
  State  University of New York at Buffalo  (R/V Dambach)  and the Center
  for  Lake Erie Area Research, Ohio State University (R/V Hydra).

      On  10 June  1975 these groups sampled two  stations approximately
 seven  miles east of Conneaut, Ohio.   Stations  sampled included an
 inshore station,  (3 miles off shore) designated  023 (lat. 42°02'4811,  long.
 80°27'08") and a more  lakeward station (7 miles off shore )  designated
 024  (lat.  42°05'54", long.  88O29'00").   Station depths were 14-14.7  m
 (023) and 22-22.7m (024).   Sampling depths were determined via a cast
 bathythermograph (model OC-10/3,  range 0-200').

      The levels  of stratification of the lake  at  Stations 23 and 24 at the
 time of the  intercomparison  were approximately as indicated  below (Fig-
 ure 141).   The dots at  each station represent the  (nominal) sampling
 depths.  At the time of sampling,  the  lake level (as measured at Erie,
 Pa.) was  approximately 1.25  m above  low water datum (LWD).

      Sampling began at Station 23  at 0930 and  Station  24 at 1130.  The
 R/V  Hydra anchored at both sites while the other  ships did not.   Apart
 from drift at  Station 24 the  ships were within  1/4 mile of each other.
 At Station 23  the winds were from  the ENE  at about  18 knots.  These
 winds diminished to 15  knots  and  switched to the  NE at Station 24.
 Waves  increased  from  approximately one  foot at Station 23 to two to
 three feet at Station 24 and hampered  sample transfer between boats.
 The wind  conditions at Station 24 caused the unanchored ship to drift
 shoreward.  The study was truncated after sampling at  this station and all
 ships returned to Conneaut Harbor to exchange samples from Station 24.

      At each  sampling horizon of each station 18  liters of water were
 taken.  This volume was split into three (six liter) subsamples and ex-
 changed among the  participating groups.   Containers were  acid-washed
 and  rinsed in  distilled and  double-distilled deionized water.  Exchanges
 occurred  immediately after sampling on Station  23 (about  103O) and ap-
 proximately  one hour after sampling  on Station 24.  All times were EST.

      A list of the  parameter determinations made by each of the three
 groups is given in  Table 77.  The following  were  selected for statistical
 analysis:  ammonia-nitrogen,  nitrate-nitrate  nitrogen, soluble  reactive
 phosphorous, total  filtered  phosphorous, total phosphorous (unfiltered) and
 total  reactive  silicate.   Among the  nutrient  parameters,  the phosphorous
 parameters are the only ones for which determinations were obtained by
 all three groups.   The nitrogen and silicate parameters were  felt to  be
 of considerable intrinsic interest.

      A summary of the operational  details of the intercomparison is
given in Table 78.   This table contains information concerning sites,

                                   332

-------
CO
GO
CO
                           PORT BURWELL, ONT.
CONNEAUT, OHIO

   24    23
                 Figure 141.   Temperature profile (°C) Secchi depths  and sampling sites,

-------
                        TABLE 77.  PHYSICAL AND  CHEMICAL  PARAMETER
                          DETERMINATIONS MADE BY  GLL,  CCIW, CLEAR
Parameter
Temperature
Dissolved Oxygen
Conductivity

PH
Secchi Transp.

Transmittance
c
Chlorophyll a

GLL
X
X
X

X
X

—

-

CCIW
X
X
X

X
X

X

X

CLEAR
X
X
X

—
X

X

X

Parameter
Alkalinity
Ammonia(NH0)
O
Nitrate-Nitrite
(NANI)
Total N
Kjeldahl N
(Organic)
Nitrate (NOg)

Total Reactive
Silicate (SiOp)
GLL CCIW CLEAR
X - X
X X
- x x

LL| Vv'
X -

X -

- x x

oo
CO
     Part. Organic
     Nitrogen

     Part. Carbon
     (Total)

     Part. Organic
     Carbon
              X
X
X
X
X
Soluble Reactive     X     X
   Phosphorus  (SRPH)
Total Soluble        X     X
   Phosphorus  (TSPH)
Total Phosphorus    X     X
   (TOPH)
Chloride             -     X
                                                        X

                                                        X

                                                        X

-------
                      TABLE 78.   SUMMARY OF OPERATIONAL DETAILS OF

                              1975 LAKE ERIE INTERCOMPARISON
co
co
en

Sampling 023
Sites and
Sampling
Depths
024


Sampling
Apparatus
Storage
N+N
NH3

SRP

TP

TSP

SiO0
GLL
1
7
11

1
11
21
Water Bottle


-
HgCl2-4°C,
plastic bottles
4°C plastic
bottles
HgCl2-4°C,
plastic bottles
4°C plastic
bottles
—
CCIW
1
7
13

1
11
19
Submersible
Pump

None*

-
None*

Sulfuric Acid-
Glass bottles
Sulfuric Acid-
Glass bottles
?
CLEAR
1
7
13

1
11
21
Water Bottle and
Submersible Pump

None*

None*
None*

1OO ml glass
bottles
4°C glass bottles

4°C plastic bottles
                                                                          (continued)

-------
                                          TABLE 78 (continued)
GO
CO
CTl
                 Analysis**
                 N+N
NH3

SRP

TP

TSP
Kjeldahl-
Nessler's
Ascorbic Acid
Ammonium  Molybdate
Ascorbic Acid
Ammonium  Molybdate
Ascorbic Acid
Ammonium  Molybdate
SulFanilamide, Phosphoric Acid,
N apthy I ethy I en e Diamide Dihydro-
chloride
Sodium Nitroprissuide

Stannous  Chloride
Ammonium  Molybdate
Stannous  Chloride
Ammonium  Molybdate
Stannous  Chloride
Ammonium  Molybdate
Oxalic Acid,  Ascorbic Acid
Ammonium  Molybdate
               *   Samples filtered then  analyzed as quickly as possible - shipboard.
               **  Both CCIW & CLEAR  used  similar equipment (Technicon AA11) and
                  reagents,  GLL employed wet lab analytical methods.

-------
 depths,  sampling methodology, storage techniques, and  analysis  methods.

 Terminology

      Some terminology that *s referred to in subsequent  sections  of the
 report is  discussed below.

      Sampling process  includes overall handling of water samples from
the time the ship arrives  on station until the samples are divided  among
the groups for analysis.   This consists of  all aspects of obtaining  the
water  samples,  i.e.,  determination of sampling sites and sampling hori-
zons,  type and utilization  of sampling devices and  sampling  containers,
and conditions and  duration of storage  of water  samples on  board ship
until they  are  subdivided for analysis.

      Analysis process refers to the  treatment  of  water samples from
the time they  have  been subdivided and transferred to the analysis
 groups'  ships  until  the final laboratory results are reported and recorded.
 This  includes  duration and methods of handling  and storage  of samples on
 board  ships, methods and duration of storage and  handling  of samples in
 the laboratories, reagents and procedures  utilized in the  analysis  process,
 and formulas  and procedures  for calculating  and recording  the analysis
 results.   The mixing  of reagents and execution of the  laboratory tests  is
 only a small portion of the  entire  analysis process.   Disagreements in
 analysis results can be due  to differences  in procedures anywhere within
 the analysis process (for  example, due to  storage of samples or due to
 ship vs.  shore laboratory analyses).   A much  more  detailed experiment
 than the Lake Erie  intercomparison would  be necessary to  separate the
 individual  effects of the various components of the analysis  process.
 Steps  in that  direction are reported  by Robertson, Elder, and Davies
 (1974).

      Sampling group is defined as  that group (CLEAR,  CCIW or GLL)
which  obtained and  subdivided  the water samples.

     Analysis group is defined as that group (CLEAR,  CCIW or GLL)
which  analyzed the  subsamples of all samples obtained  by  the three
sampling groups.

     Subsample variation  represents that portion  of  the variability
in analytic results due  only to variability in the analytic process.  It
excludes all effects due  to variability among  water samples.  It  is
estimated  from differences among the various analytic results on the
same  water  samples (analysis group by sampling group by sampling
depth  mean square).   Subsample variation  is sometimes referred to
in subsequent discussion as  "subplot" variation.


                                    337

-------
      Whole sample  variation is the variability that enters into  compari-
sons  among sampling groups or among sampling horizons.  The whole
sample variation reflects both variability among  different water samples
as well as  variability among individual analyses  performed  on the same
water sample.   The variability among  water samples is due both to
inherent variability in the lake water as  well  as to differences  among
the sampling processes.   Estimates of whole  sample variation are  based
on comparisons  among  the  averages of all  determinations on the  same
water sample (in particular,  sampling  group by sampling depth mean
square divided by number of analysis groups).  It  is sometimes referred
to as  "whole plot" variation.

SUMMARY  OF MAJOR  FINDINGS

      A considerable number of statistical analyses were performed on
the intercomparison  data.   Among the  conclusions  arrived at  are the
following:

      1 .   For each parameter but ammonia,  there  are statistically signi-
      ficant differences among analysis  group  average determinations.
      Both analysts groups  report similar average  determinations for
      ammonia,  however the variabilities are  rather  different.  At  each
      station, the analysis group  differences are  especially  large  for
      soluble reactive phosphorous.  (Note  that a "statistically significant"
      difference  is not necessarily a "practically significant" difference
      and  vice versa.  What is considered  to  be  a  "practically significant"
      difference  depends heavily on the  uses to which the data  are to
      be put.  A 10  percent discrepancy might be quite  acceptable for  some
      purposes but totally out of the question for others.)

      2.   No significant sampling  group differences are  evident.

      3.   Sampling depth  effects are important especially at Station 23.

      4.   No systematic differences are evident between  measurements
      on samples obtained via submersible  pump or water bottles.

      5.   The average nutrient levels at Station 23  are consistently
      higher  than those at Station  24.   Station 23 is more shoreward
      thus more  susceptable to shoreline processes (tributary inputs,
      mixing,  resuspension).

      6.   The subsample variability is about the same at stations  23 and
                                  338

-------
      24 but the whole sample variability is greater at Station 24 than at
      Station 23.  This is probably due to the rougher  surface conditions
      at Station 24 and the shoreward drift of two of the vessels.  Both
      factors would contribute to  heterogeneity among the water samples.

      7.  The  variability between replicate pump determinations  is gener-
      ally smaller than the whole sample variability.  The variation
      between  replicate pump measurements is probably an underestimate
      of variability.   Silicate  is an exception.

      Results  1 and 2 are in direct agreement with results reported by
Robertson,  Elder,  and Davies (1974) based on a similar intercomparison
that was carried  out  in  1972  on Lake  Ontario.

Experimental  Data

      The experimental data are given in Table 79,  which contains informa-
tion about the  analysis group (ANLGRP—1  = CLEAR,  2 = CCIW, 3 =
GLL),  sampling depth (in meters),  sampling site (23 or 24),  method by
which CLEAR  collected comparable water  samples  (OSUCOD—W = water
bottle,  A = pump replicate 1, B  =  pump replicate  2), soluble reactive
phosphorous (SRPH),  total soluble phosphorous (TSPH), total phosphorous
(TOPH), nitrate-nitrite (NANI), ammonia (NH3),  and total reactive silicate
(SiO  ).  Of the 66  observations contained  in Table 79, the 54  observations
corresponding  to  OSUCOD = W represent the 18 CLEAR water bottle sam-
ples and the samples collected by CCIW (18) and GLL  (18).   These 54
observations contain all  the  information  pertaining  to comparisons  among
analysis groups and most of the information  pertaining to comparisons
among  sampling groups.   The primary data analyses were carried out on
these 54 observations.

      The CLEAR replicate pump measurements correspond  to OSUCOD =
A or B.  There are  three pairs  of such replicate  pump  measurements  at
each  sampling  site.   Comparisons between the replicate  pump measure-
ments yield information  about pump sample to pump  sample variability.
Comparisons between the pump and water  bottle measurements yield
information about the presence of any systematic discrepancies between
the two methods of sampling.   Comparisons  of CLEAR pump  and water
bottle measurements  were carried out on  these  12  observations.

      Blank spaces in the various data columns correspond to missing
data.   For example,  CCIW did not perform ammonia analyses, so that
when ANLGRP =  2  the Nh^  column is blank.
                                   339

-------
TABLE 79.
BASIC DATA  ON SIX CHEMICAL  PROPERTIES
     OF WATER SAMPLES
OBS ANLGRP
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
1
1
1
2
2
2
3
3
3
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
1
1
1
SMPGRP
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
3
3
3
DEPTH
1
7
13
1
7
13
1
7
13
1
7
13
1
7
13
1
7
13
1
7
13
1
7
13
1
7
13
SITE
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
OSUCOD SRPH
W
W
W
W
W
W
W
W
W
A
A
A
B
B
B
W
W
W
W
W
W
W
W
W
W
W
W
11 .7
10.9
7.6
12.0
10. 0
7.8
14.2
14.2
15.6
11 .4
10.7
5.9
11 .0
11.6
6.2
10.9
11 .3
9.1
9.6
9.6
7.5
14.9
15.6
9.8
11.7
11 .8
7.7
TSPH
15.0
13.3
11 .0
18.0
15.0
15.0
14.2
19.2
16.3






14.8
15.4
12.1
15.0
14.0
12.0
14.9
20.6
12.0
15.6
14.8
11 .0
TOPH
28.0
19.8
26.6
30.0
31 .0
27.0
36.1
29.5
25.1
25.1
26.5
23.7
26.0
25.1
24.7
25.3
25.3
21 .8
26.0
26.0
26.0
33.2
32.4
30.2
27.8
32.2
25.0
NAN I
302
295
233
326
318
264



300
290
240
295
295
235
296
300
254
319
317
270



302
288
240
NH3
58.0
61 .3
51 .0



88.0
55.0
55.0
60.5
60.2
50.0
58.0
56.0
50.0
54.0
53.4
49.7



53.0
60.0
28.0
59.0
56.5
51 .0
SiO2
340
320
320
310
290
280



430
435
435
310
325
405
320
320
340
300
270
270



300
300
300
                                                              (continued)

-------
                                 TABLE 79 (continued)
OBS  ANLGRP  SMPGRP  DEPTH  SITE  OSUCOD  SRPH  TSPH  TOPH  NANI  NH3   SiO2
 32
 33

 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
1
1
1
2
2
2
3
3
3
1
1
1
1
1
1
1
1
1
2
2
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
13

 1
11
21
 1
11
21
 1
11
21
 1
11
21
 1
11
21
 1
11
21
 1
11
21
 1
23
23

24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
24
W
W

W
W
W
W
W
W
W
W
W
A
A
A
B
B
B
W
W
W
W
W
W
W
11 .0
11 .0
7.5
15.6
14.2
15.6
4.6
1.6
2.5
3.8
1.3
1.8
6.3
7.0
5.6
5.0
2.1
1 .4
5.5
2.3
2.5
2.7
2.1
2.2
2.3
1.7
2.0
5.6
18.0
19.0
14.0
15.6
15.6
15.6
8.6
5.6
11 .6
8.9
6.5
8.0
6.3
7.0
7.7






7.9
6.2
6.2
8.0
6.9
8.0
5.6
31 .0
30.0
29.0
30.2
33.2
23.6
19.4
14.6
22.6
19.0
17.0
23.0
17.8
10.7
16.4
19.4
16.3
17.2
15.3
19.5
17.2
18.2
13.6
14.6
17.0
17.0
15.0
17.1
324
319
252



201
207
347
216
223
381



2O2
172
248
210
207
305
162
206
245
171
232
268




61 .0
59.0
42.0
36.5
31.3
45.7



39.0
28.0
44.0
38.1
27.3
46.5
36.5
31 .4
57.7
29.0
34.2
35.0



39.0
340
310
270



230
175
370
220
170
310



325
325
255
450
270
195
240
190
215
180
150
200

(continued)

-------
                                   TABLE 79 (continued)







OBS  ANLGRP  SMPGRP  DEPTH  SITE  OSUCOD   SRPH  TSPH  TOPH   NANI   NHg  SiO2



oo
-pi
ro







56
57
58
59
60
61
62
63
64
65
66
3
3
1
1
1
2
2
2
3
3
3
2
2
3
3
3
3
3
3
3
3
3
11
21
1
11
21
1
11
21
1
11
21
24
24
24
24
24
24
24
24
24
24
24
W
W
W
W
W
W
W
W
W
W
W
7.0
6.3
4.9
2.0
2.3
4.7
2.0
2.0
6.6
7.7
5.6
7.7
7.0
8.3
5.3
5.6
12.0
7.7
5.6
7.2
7.7
5.6
16.4
18.4
49.5
17.1
16.7
21.0
15.0
12.0
17.8
10.7
16.4


208
195
242
230
212
264



24.0
15.0
35.5
33.8
36.0



44.0
58.0
28.0


300
225
325
260
170
170




-------
Experimental Results

      A considerable number of statistical analyses and data displays
were carried out on the intercomparison data.   The  main conclusions
from these analyses were summarized  in the section titled "Summary  of
Major Findings".  This section  contains a more extensive,  but still rela-
tively brief and  non technical discussion of the bases of the conclusions.

      The principal result of this section is  statistical evidence of differ-
ences among analysis groups but not among sampling groups.  This is in
direct agreement with results reported  by Robertson, Elder,  and Davies
(1974) based  on  a similar intercomparison that was carried out in 1972
on Lake Ontario.

      The intercomparison experiment was carried out at two  sampling
stations (23 and  24) on Lake Erie.   Because the  horizon depths and
nutrient levels at the two sites  were quite different and since  the  whole
sample variability at  Station 24 exceeded that  at  Station 23 (for some
considerably), the data from each of the two stations was  analyzed sepa-
rately.  Thus, no variance estimates have been pooled across stations.
Some comparisons (particularly those  involving analysis groups) might
be reexamined with variance estimates  pooled  across stations, for in-
stance where pooling  seems sensible.   The increased degrees of freedom
might increase the sensitivity of  the tests.

       In the course of  several  of the analyses,  it appeared from the
 data that certain determinations  might be out line relative to the rest.
 In such cases the data were reanalyzed after omitting the suspect value
 or values.   The results  of both  the original and the reanalyses  are
 reported.

       Overall Average Values.   Table 80 contains the overall average
 values by station of  each of the  six nutrients.  The averages are taken
 over analysis group,  sampling group,  and sampling  depth.   It is immed-
 iately evident that the average values are consistently higher at site 23
 than at site  24.  The discrepancies between the two sites vary from  19
 percent to 66 percent of the site 23 average values.

       This observation is in agreement  with other data collected.   Sta-
 tion 23 is more shoreward,  thus more susceptable to shoreline processes
 (tributary  inputs, mixing,  sediment resuspension).   Indeed,  it appears
 that  station 23 is located deeper within a nutrient rich surface plume
 (see Figure  141 and  section on sampling depth effects) than Station 24.
                                   343

-------
                    TABLE 80.   OVERALL  AVERAGE DETERMINATIONS BY SITE
      Parameter (ppb)
                                     Site 23 Avg.
                      Site 24  Avg.
                       Difference
co
-ti
Soluble reactive phosphorus


Total soluble phosphorus ffiltered")


Total phosphorus (unfiltered)


Nitrate - nitrite


Ammonia


Silicate
 11.42  (11.48*)


 15.07


 28.57


289.94


 55.27  (54.93**)


305.56
  3.86


  7.36


 17.93 (16.71**)


233.89


 35.33


227.78
 7.56  (7.62*)


 7.71


10.64  (11.86**)


56.05


19.94  (19.6***)


77.78
            Reanalysis of site 23 soluble reactive  phosphorus data after deleting observation 24.
     **     Reanalysis of site 24 total phosphorus data after deleting observation 58.
     ***    Reanalysis of site 23 ammonia data after deleting observation 7  and 24.

-------
     Whole Sample, Subsample,  and Pump to Pump  Variability.  The
intercomparison is  an  example  of a  split plot  experiment.  Comparisons
of analysis groups are made within the same water samples whereas
comparisons of sampling  groups, depths, or sites are  made among  diffei
ent water  samples.  Thus comparisons of sampling groups or sampling
depths reflect  whole sample variation whereas comparisons of analysis
groups  reflect only subsample variation.  This implies that different com-
parisons require different error yardsticks.

     In addition to  whole sample and subsample variability, another vari-
ability estimate can be obtained by comparing  the determinations based
on the replicate CLEAR pump samples.  Conceptually, these pump to
pump variability estimates  should approximately agree  with or  exceed the
whole sample errors,  but except  for silicate they turn  out to be about
half the value.  Table 81  contains the estimated whole sample,  subsample,
and  pump  to pump variances  of each of the six chemical properties, by
site.  Beside each  variance estimate is the degrees  of freedom on which
it is based.  A number  of  comparisons can be made from the  table.

      1 .  The  whole sample variance estimates are  consistently greater
      at Station 24  than  at  Station 23.  Although  it is difficult to compare
      variances based  on just four degrees of  freedom, there  is some evi-
      dence of greater whole sample variation at Station 24 than at Station
      23.

      2.  Except for silicate,  there  is  no evidence of greater subsample
      variation  at one  station than at another.

      3.  There is  some suggestion  that  pump to  pump variation is
      greater at Station 24 than at Station 23, although the evidence  is
      weaker than that for  whole sample  variations.

      4.  With  the  exception of silicate,  the whole sample variation is
      one and  one  half to three times the pump to pump  variation.

     Analysis Group Effects.   The average determinations for the three
analysis groups (averaged over sampling group and depth) were obtained
and compared at each site. Table 82 contains, for each  of the  six chemi-
cal  properties, the three analysis group  averages, the estimated standard
errors  (based on the subsample variation) appropriate  for assessing  dif-
ferences between pairs of averages, and the  significance levels at which
the  averages are significantly diffferent.

     At site 23 the analysis group averages differ significantly  for  all
parameters but ammonia.  (The  ammonia determinations differ  in  varia-
bility but  not in average  value.)  At site 24 there is statistical evidence

                                   345

-------
                    TABLE 81 .
SUBSAMPLE, WHOLE SAMPLE,  PUMP-TO-PUMP
        VARIANCES  - BY SITE
                                                  Station 23
      Property
         Subsample
         Variation
                                                         d.f.
Whole Sample
Variation    d.f.
Pump to  Pump
Variation    d.f.
soluble reactive phosphorous
total soluble phosphorous (filtered)
total phosphorous (unfiltered)
nitrate-nitrite
ammonia

silicate
2.62(0.24*)
3.16
3.71
27.47
82.31
(40.20***)
122.22
8(7*)
8
8
4
4
(2 )
4
0,27(0.31*)
0.60
1 .55
36.24
23.02
(6.84***)
77.78
(4*)
4
4
4
4
(4***)
4
0.18 3
no pump samples
0.63 3
12.5 3
3.98 3

4566.67 3
CO
-Pi
CTl
                                                  Station  24
Property Subsample Whole Sample Pump to
Variation d.f. Variation d.f. Variation
soluble reactive phosphorous
total soluble phosphorous (filtered)
total phosphorous (unfiltered)
nitrate-nitrite
ammonia
silicate
0.10 8
0.98 8
27.47(4.38**)(7**)
28.22 4
65 . 72 4
899.31 4
0.36 4
1 .87 4
22.71(4.80**)(4**)
1441.35 4
59 . 23 4
1 949 . 66 4
0.25
no pump
4.51
756.33
24.14
3708.33
* Reanalysis of site 23 soluble reactive phosphorus data after deleting observation
** Reanalysis of site 24 total phosphorus data after deleting observation 58.
*** Reanalysis of site 23 ammonia data after deleting observation 7 and 24.
Pump
d.f.
3
samples
3
3
3
3
24.

-------
                       TABLE 82.  ANALYSIS GROUP AVERAGES - BY SITE
Property
Station 23
sol . react . phos .
tot. sol. Phos. (filtered)
tot. phos. ('unfiltered)
nitrate-nitrite
ammonia
silicate
station 24
sol . react . phos .
tot. sol. phos. (filtered)
tot. phos. (unfiltered)
nitrate-nitrite
ammonia
silicate
Analysis Group Averages
CLEAR CCIW GLL

10.30
(10.30*)
13.67
26.87
278 . 89
54.88
(54.88***)
317.78

2.77
7.26
20.70
(17.89**)
223 . 67
35.22
252 22

9.56
(9.56*)
15.56
28.44
301.00
^~^~
293 . 33

2.40
7.96
17.33
(17.33**)
244 . 1 1
—
203.33

14.41
(15.31*)
16.00
30.39
—
55.67
(54.75***)
— —

6.41
6.87
15.74
(15.74**)
—
35.44
— —
Std. Err. of
Difference d.f.

.765 8
(+) (7*)
.838 8
.905 8
2.47 4
4.27 4
(3. 54+++) (2***)
5.22 4

.147 8
.466 8
2.47 8
(++) (7**)
2.50 4
3.82 4
14.14 4
Significance
Level

.0008
(.0001*)
.05
.01
.002
.86-
(.97***)
.01

.0001
.12
8
( .20**)
.002
.96
.03
CO
      *
      **
      ***
Reanalysis of site 23 soluble reactive phosphorus  data after deleting observation 24.
Reanalysis of site 24 total phosphorus data after deleting  observation 58.
Reanalysis of site 23 ammonia data after deleting observations 7 and 24.
After reanalysis std. err. of CLEAR,  CCIW diff  = 0.232; std  err of CLEAR, GLL
and  CCIW,  GLL diffs = 0.253
After reanalysis std. err. of CLEAR,  CCIW and  CLEAR, GLL diffs = 1.075; std.  err. of
CCIW,  GLL diff = 0.986
After reanalysis

-------
 of analysis  group differences for  soluble  reactive phosphorous, nitrate-
 nitrite, and silicate.   At both sites the analysis group differences  are
 especially large  for soluble  reactive phosphorous.

      Several  of  the discrepancy patterns  are consistent between sites.
 GLL's soluble reactive phosphorous levels are  relatively high at  both
 sites.   CLEAR's nitrate-nitrite levels are smaller  than CClW's and
 CLEAR's  silicate levels are greater than CCIW's at both sites.  CLEAR's
 ammonia levels have the same  mean  but  are less variable  than GLL's
 at both sites.

      Sampling Group  Effects.  The average determinations  for  the  three
 sampling groups  (averaged over analysis  group  and  depth) were obtained
 and compared at each  site.  Table 83  contains,  for  each of the six  chem-
 ical properties,  the three sampling group averages, their estimated stan-
 dard errors (based on the  whole sample variation),  and the significance
 levels  at which they are significantly  different.

     As  can  be seen from Table 83 no significant sampling group effects
 are evident  at either site.

      Sampling Depth Effects .   The average  determinations for the  three
 sampling depths (averaged over analysis group and  sampling group) were
 obtained and compared for each site.  Table 84  contains,  for  each of the
 six chemical properties, the three sampling  depth averages,  their esti-
 mated standard errors (based on the whole sample  variation), and the
 significance  levels at which they are significantly different.

     At site 23  significant depth effects are  evident for all six chemicals
 properties.  There is consistently a sharp drop  in nutrient levels  between
 7  and  13 meters.

     At site 24 the depth  effects are  either nonsignificant or at best
 marginally significant.   This is due to a  combination  of higher standard
 errors  at site 24  (especially for nitrate-nitrite, ammonia, and  silicate)
 and less pronounced changes with depth.

     It is  interesting to note the drop  in  concentration  levels between 1
 meter and 13  meters at Station 23 and  (with the exception of nitrate-
 nitrite) a similar  drop  in concentration  levels between 1 meter and  11
 meters at  Station 24.   However,  at Station 24 the  concentration levels
 remain the same or actually rise  between 11  meters and 21 meters.

      Comparison  of Pump and Water  Bottle  Samples  Collected and
Analyzed by  CLEAR.    Water samples can be collected  either by a  sub-
 mersible pump or by water  bottle samplers.   In order  to determine

                                   348

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                       TABLE 83.  SAMPLING  GROUP AVERAGES - BY SITE

Property
Station 23
sol . react . phos .

tot. sol. phos. (filtered)
tot. phos. (unflltered)
nitrate-nitrite
ammonia

silicate
Station 24
sol. react, phos.
tot. sol. phos. (filtered)
tot. phos. (unfiltered)
nitrate-nitrite
ammonia
silicate
Sampling Group Averages
CLEAR CCIW GLL

11 .56
(11 .56*)
15.22
29.23
289 . 67
61 .38
(56.23***)
310.00

3. 83
7.80
17.83
(17.83**)
262.50
37.42
245 . 83

10.92
(11 .82*)
14.53
27.36
292 . 67
49.68
(53.46***)
303.33

3.54
7.O6
16.37
(16.37**)
214.00
29.37
195.83

11 .79
(11 .79*)
15.47
29.11
287.50
54.75
(54.75***)
303 . 33

4.20
7.22
19.58
(17.21**)
225.17
39.22
241 .67
Std. Ern of
Difference d.f.

0.42 4
*
(+) (4*)
0.64 4
1 .02 4
4.92 4
3.92 4
(+++) (-4***^
7.20 4

0.48 4
1 .12 4
3.89 4
(-K-) (4**)
31.00 4
6.28 4
36.05 4
Significance
Level
/•^/"\
.22
(.75*)
.40
.23
£+ 4
.61
.10
(.70***)
.61

.53
.79
.73
(.70**)
.36
.35
.40
* Reanalysis of site 23 soluble reactive phosphorus data after deleting observation 24.
** Reanalysis of site 24 total phosphorus data after deleting observation 58.
*** Reanalysis of site 23 ammonia data after deleting observations 7 and 24.
+ After reanalysis std err of CLEAR, GLL diff = 0.452; std err of CLEAR, CCIW and
CCIW, GLL diffs = 0.492
++ After reanalysis std err of CLEAR, CCIW diff = 1.79; std err of CLEAR, GLL, and
CO
-P>
UD
             CCIW,  GLL diffs  =  1 .95

             After reanalysis std err of  CLEAR,  CCIW diff

             CCIW,  GLL diffs  =  2.53
3.02; std err of CLEAR,  GLL,  and

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                         TABLE 84.  SAMPLING DEPTH  AVERAGES - BY SITE
Property
Station 23
sol. react, phos.

tot. sol. phos. (filtered)
tot. phos. (unfiltered)
nitrate-nitrite
ammonia

silicate

Station 24
sol . react . phos .
tot. sol phos. (filtered)
tot. phos. (unfiltered)

nitrate-nitrite
ammonia
silicate
Sampling Depths Averages
1 meter

12.40
(12.40*)
15.68
29.73
311 .50
62.17
(57.01**)
318.33
1 meter

4.61
8.09
21 .87
(19.06**)
198.00
37.17
238.33
7 meter

12.07
(12.07*)
16.32
29.93
3O6.17
57.53
(57.53***)
301 .67
7 meter

3.60
6.73
14.68
(14.68**)
212.50
34.88
1 80 . 00
13 meter

9.80
(10.70*)
13.22
26.03
252.17
46.12
(49.90**)
296.67
13 meter

3.37
7.26
17.23
(17.23**)
291 .17
33.95
265.00
Std Err of
Difference d.f.

0.42 4
(+) (4*)
0.64 4
1 .02 4
4.92 4
3.92 4
(+++) (4***)
7.20 4


0.48 4
1.12 4
3.89 4
(++) (4**)
31.00 4
6.28 4
36.05 4
Significance
Level

0.008
(0.05)
O.O2
0.03
0.002
0.04
(O.O9***)
0.08


0.12
0.53
0.28
(0.20**)
0.08
0.87
0.17
oo
en
o
       **
       ***
Reanalysts  of site 23 soluble reactive phosphorus data after  deleting observation  24.
Reanalysis  of site 24 total phosphorus data after deleting  observation 58.
Reanalysis  of site 23 ammonia data after  deleting observations  7  and 24.
After reanalysis std err of CLEAR,  GLL diff =  0.452;  std err of CLEAR, CCIW,  and
CCIW,  GLL diffs » 0.492
After reanalysis std err of CLEAR, CCIW diff = 1.79; std err  CLEAR,  GLL and CCIW,
GLL diffs = 1 .95
After reanalysis std err of CLEAR,  CCIW diff = 3.02;  std err CLEAR, GLL and CCIW,
GLL diffs = 2.53

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whether any systematic  effects are introduced by the method of sampling,
CLEAR  collected two pump  samples and  a water bottle  sample at each of
the six  site-depth combinations.   Comparison of the replicate pump mea-
surements provides  direct information about  pump  sample to pump sam-
ple variability.   Comparison of pump  and water bottle  measurements
provides information concerning the existence of systematic effects  due
to sampling  method.   The analysis results are summarized in Table 85.
This  table shows that with the exception  of silicate,  the pump to  pump
variability is consistently smaller than the whole sample variation and the
pump to pump variation at site  23 is smaller than that  at site 24.

      The "t-ratio" column summarizes the statistics to test for systema-
tic differences  between the two  sampling methods.   The t-ratio is formed
by dividing the difference between average pump determination and water
bottle determination by an estimate  of its standard  error based on pump
to pump variation.  Where the pump to  pump variation  is similar between
sites, the 3 degrees of  freedom variance estimates at  each site are
pooled to form a more precise  6  degrees of freedom variance estimate.
Generally speaking,  no significant systematic differences between the  two
sampling methods are apparent.   However inferences based on just three
degrees of freedom  or even six are not  very powerful.


DISCUSSION

     A  number  of questions and issues  arose in the process  of  analyzing
the data.  Several of these  are indicated below:

      1 .   A number  of determinations  were identified that seemed to be
      out of line.  These were sometimes isolated  determinations, but
      also sometimes involved all  the determinations from the same
      water sample.   Where possible outliers are present, the basic data
      should be reviewed to  determine whether or not the suspect data
      are erroneous  and if so, why.  Are the outlying values  due to
      clerical errors, error in the analysis procedure,  errors in mixing
      or calibrating  reagents,  or mixups  in samples?  Can the appropri-
      ate values be determined?  Are these "out of line" observations
      just normal variation?

      2.   Why is the variation between replicate pump samples generally
      smaller than the whole sample variation?  Which,  if either, is a
      true estimate of sample to sample  variation?  Why is  this  relation-
      ship reversed  for silicate?

      3.  There was  some confusion about sampling depths at the bottoms
      of both  stations.  At Station 23, both CLEAR and CCIW report

                                   351

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                          TABLE  85.   COMPARISON OF CLEAR PUMP AND
                             WATER BOTTLE MEASUREMENTS - BY SITE
Properties
Station 23
Soluble reactive phosphorus
Total soluble phosphorus (filtered)
Total phosphorus (unfiltered)
Nitrate-nitrite
Ammonia
Silicate
Station 24
Soluble reactive phosphorus
Total soluble phosphorus (filtered)
Total phosphorus (unfiltered)
Nitrate-Nitrite
Ammonia
Silicate
Pump
Average

9.4667
Water
Bottle
Msmnt.

10.0667
Pump to
Pump
Var.

0.18
Whole
Sample
Variation

0.31*
t-ratio

-1 .82
d.f.

6
Signifi-
cance
Level

0.12
no pump sample determinations made
25 . 1 833
275.8333
55.78
390.00

3 . 1 333
28.133
276.6667
56.77
326.67

2 . 900O
0.63
12.5
3.98
4566.67

0.25
1.55
36.24
6.84***
77.78

0.36
-5.27
-O.33
-0.70
1 .39

0.706
3
3
3
6

6
0.014
0.76
0.54
0.22

0.50
no pump sample determinations made
1 7 . 4833
224 . OOOO
39.58
303 . 33
1 8 . 8667
251 .6667
37.83
258.33
4.51
756.33
24.14
3708.33
4.80**
1441 .35
59.23
1949.66
-0.92
-1 .422
0.50
0.99
3
3
3
6
0.44
0.26
0.66
0.36
tn
           Reanalysis of site 23 soluble  reactive  phosphorus  data  after deleting observation 24.
           Reanalysis of site 24 total phosphorus data after deleting observation  58.
           Reanalysis of site 23 ammonia data  after deleting observations 7 and  24.
**
***

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      sampling at 13 meters whereas GLL reports sampling  at  11  meters.
      At Station  24,  both CLEAR and GLL report  sampling at 21 meters
      whereas  CCIW reports sampling at  19  meters.  These discrepancies
      in sampling depths were ignored for the  purpose of this analysis,
      however  they could possibly introduce bias or variability into the
      data.   This should be kept in mind  when preparing  protocols  for
      future  intercomparisons.

      4.  Generally speaking, the sampling variation at Station 24 was
      larger than that at Station 23, sometimes substantially so.   Does
      heterogeneity of samples vary  substantially from station to station?
      If so,  this should be taken into account when designing future  sam-
      pling procedures and when analyzing the  data.

      5.  It  would be useful to  repeat the  intercomparison at several dis-
      tinct points in time,  for instance, weeks or  months apart, and to
      incorporate more  replication at each time.   This  would provide
      information as to  whether there is time to time random variation of
      the results within laboratories and as to whether the discrepancies
      between laboratories are random or  systematic.   The separation of
      systematic and random  sources of variation  might give clues  about
      their nature, thereby enabling  sources  of variation to be eliminated.
      See Robertson,  Elder,  and  Davies (1974) for an example  of this.
REFERENCE

Robertson,  Andrew,  Floyd Elder and Tudor Davies.   1974.  IFYGL chem-
      ical intercorYparisons.   Proc.  17th  Conf.  Great Lakes Res.  Internat.
      Assoc. Great 'Lakes Res.  p.  682-696.
                                  353

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
 i. REPORT NO.
    EPA-600/3-80-062
 4. TITL
                              2.
   ITLE AND SUBTITLE
   Lake  Erie  Nutrient Control Program - An Assessment
   of  its  Effectiveness in Controlling Lake
   Eutrophication
                                      6. PERFORMING ORGANIZATION CODE
                                      3. RECIPIENT'S ACCESSI ON-NO.
                                      5 REPORT DATE

                                        JULY 1980 ISSUING  DATE.
 7. AUTHOR(S)
                                                           8. PERFORMING ORGANIZATION REPORT NO
   Charles  Herdendorf
9. PERFORMING ORGANIZATION NAME AND ADDRESS
   The Ohio  State  University
   484 West  12th Avenue
   Columbus,  Ohio   43210
                                       10. PROGRAM ELEMENT NO.
                                       11. CONTRACT/GRANT NO.
                                                               R802543
 12. SPONSORING AGENCY NAME AND ADDRESS
  Environmental Research  Laboratory
  Office of Research and  Development
  U.  S.  Environmental Protection Agency
  Duluth, Minnesota  55804
                                       13. TYPE OF REPORT AND PERIOD COVERED

                                           Final  1973-76
                                      14. SPONSORING AGENCY CODE
                                           EPA/600/03
 15. SUPPLEMENTARY NOTES
  Large Lakes Research Station,    ERL-Duluth
  9311 Groh Road,   Grosse  He,  Michigan  48138
 16. ABSTRACT    ~~~                      "                  —~	~~	
      A three-year  assessment of nutrient control  efforts was conducted in the western
 and central  basins  of Lake Erie during the period June 1973 to June 1976.  The
 objective of the study was to determine recent  trends  in lake eutrophication and  water
 quality which may  be  related to recent attempts  to control  nutrient loadings to these
 basins.  The assessment was accomplished by visiting approximately 50 stations at
 nearly monthly  intervals during the ice-free periods.   Over 25 water quality,
 meteorologican  and  biological parameters were routinely determined shipboard or on
 samples collected  at  a typical  station.  Measurements  were  taken at several depths
 in order to  characterize the various strata of water in the lake and to permit
 volume-weighted calculation of nutrient concentrations and  quantities.  Data from
 previous limnological  surveys as far back as 1928 were compared with the results  of
 the present  study  to  establish longterm trends,  as well  as  recent trends since the
 last comprehensive  survey in 1970.
      The fundamental  conclusion of this assessment is  that  during the first half  of
 this decade  no  significant decrease in the loading of  nutrients to Lake Erie has  taken
 place.  Therefore,  during this period the concentrations and quantities of nutrients
 within the waters of  the lake have remained relatively stable.  An encouraging sign
 of nutrient  control is that although no decreases have been observed, the constant
 increases which have  taken place in preceeding decades have been stopped.
 7.
                               KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                             b.IDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
   Algae, Nutrient,
   Benthos
Hydrodynamic
Lake Erie
06
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                                           354
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