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                                    FOREWORD
     The Great Lakes National Program Office (GLNPO) of the United States
Environmental Protection Agency was established in Region V, Chicago to
focus attention on the significant and complex natural resource represented
by the Great Lakes.

     GLNPO implements a multi-media environmental management program drawing
on a wide range of expertise represented by Universities, private firms,  State,
Federal, and Canadian Governmental Agencies and the International Joint
Commission.  The goal of the GLNPO program is to develop programs, practices
and technology necessary for a better understanding of the Great Lakes Basin
Ecosystem and to eliminate or reduce to the maximum extent practicable the
discharge of pollutants into the Great Lakes system.  The Office also coordi-
nates U.S. actions in fulfillment of the Agreement between Canada and the
United States of America on Great Lakes Water Quality of 1978.

     This study was supported by a GLNPO grant to the University of Michigan
at Ann Arbor for investigating the phytoplankton assemblages of the nearshore
zone of southern Lake Michigan.

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                                            EPA-905/3-79-001  c- 2.
       PHYTOPLANKTON ASSEMBLAGES OF THE
  NEARSHORE ZONE OF SOUTHERN LAKE MICHIGAN
                     by
      E.  F.  Stoermer and Marc L. Tuchman
        Great Lakes Research Division
           University of Michigan
         Ann Arbor, Michigan  M8109
               Grant R005337 01
               Project Officer

               David C. Rockwell
     Great Lakes National Program Office
            536 South Clark Street
           Chicago, Illinois  60605
UNITED STATES ENVIRONMENTAL  PROTECTION AGENCY
                   REGION  V
           CHICAGO, ILLINOIS  60609
      U.S. Environmental Protection Agency
      Region 5, Library (PL42J)
      77 West Jackson Boulevard, 12th Ftoor
      Chicago, It 60604-3590

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                                  DISCLAIMER

     This report has been reviewed by the Great Lakes National Program Office,
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 constitute endorsement or recommendation for use.
                                      11

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                                   ABSTRACT








     Phytoplankton samples from nearshore stations along the Indiana coast of




Lake Michigan were analyzed to determine the composition and seasonal abundance




of phytoplankton populations in this region.  Occurrence patterns of major




populations and population groups were inspected to detect unusual patterns




which might be indicative of particular inputs to this region of Lake




Michigan.  As might be expected in a local inshore region where physical mixing




and advection processes are relatively intense, phytoplankton distribution is




highly variable.  The largest general effect noted is a continuing increase in




groups other than diatoms, apparently as a result of silica depletion resulting




from phosphorus enrichment.  The singular exception to this trend is the




abundant occurrence of Cyclotella comensis. a diatom which has only recently




become abundant in Lake Michigan and which can apparently tolerate very low




silica levels.  An effect more specific to the region is the atypically high




abundance of members of the diatom genus Nitzschia during some sampling




periods.  High abundance of these organisms is often associated with organic




nitrogen and ammonia inputs, and this appears to be the case in the Indiana




nearshore region of Lake Michigan.  Occasional occurrences of populations such




as Thalassiosira sp. and Skeletonema spp. were also noted in the samples.




These appear to be associated with isolated water masses and may be indicative




of local areas of high conservative ion input.  It should be noted that the




thermal bar period, when the effects of conservative ion loadings might be




expected to be most intense, was not represented in the samples examined.




Another characteristic of the phytoplankton assemblages in the Indiana




nearshore region is the high abundance of microflagellates, especially






                                        iii

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organisms which apparently belong to the Haptophyceae or Prasinophyceae.



Although these organisms are known to be abundant in areas of the Great Lakes



which are substantially perturbed, and are apparently generally increasing in



Lake Michigan, little is known about their specific ecology due to



methodological difficulties in identification.  Further research should be



devoted to this topic.
                                         iv

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                                   CONTENTS

Abstract	.	iii
List of Figures	vi
List of Tables. .  .	vi
Acknowledgments	 .  .vii

  1.  Introduction	1
  2.  Materials and Methods 	  4
  3.  Results
        Overall Abundances of Major Algal Groups	  .  7
        Regional and Seasonal Trends in Abundance of Selected Taxa. .  . 10
          Bacillariophyta 	 10
          Chlorophyta	28
          Cryptophyta	.28
          Cyanophyta	  . 32
          Microflagellates	36
  4.  Discussion	38

References	45
Appendix Figures	47
Appendix Table 1	80

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                                    FIGURES

   Number                                                                Page

     1    Sampling station locations;  southern  Lake  Michigan,  1977.  ....   5

     2    Seasonal Distribution and  Abundance Trends of  the  Total
         Phytoplankton Assemblage	   9

     3    Distribution of Asterionella formosa	11

     4    Distribution of Cvclotella comensis  	  13

     5    Distribution of Cvclotella crvpfrica	14

     6    Distribution of Cvclotella pseudostelligera 	  16

     7    Distribution of Cvclotella stelligera 	  17

     8    Distribution of Fragilaria^ crotonensis	19

     9    Distribution of Nitzschia  acicularis	20

    10    Distribution of Nitzschia,  fonticola	22

    11    Distribution of Nitzschia  palea 	  23

    12    Distribution of Stephanod^gous minutus	  24

    13    Distribution of Svnedra filiformis	26

    14    Distribution of Tabellarifl flocculosa, var. linearis 	  27

    15    Distribution of Chlamvdomonas spp	29

    16    Distribution of Scenedesmus spp	30

    17    Distribution of Crvpfromona,s ovata	31

    18    Distribution of Anabaena f}os-aauae  	  33

    19    Distribution of Anacystis  incerta 	  34

    20    Distribution of Oscillatoria bornetii 	  35

    21    Distribution of Haptophyte sp. #1	37


                                     TABLE

Table 1  Statistical summary of major algal  groups in southern Lake
         Michigan, 1977	8
                                       vi

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                               ACKNOWLEDGMENTS








     We would like to thank Ted B. Ladewski for his assistance on the computer



analysis used in this study.  We would also like to acknowledge the U.S.



Environmental Protection Agency for collecting the samples and performing the



physico-chemical analyses.
                                       vii

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                                 INTRODUCTION








     Compared to most areas of the Great Lakes, the southern shoreline region



of Lake Michigan has enjoyed a relatively long period of study.  Qualitative



records of phytoplankton and benthic algal occurrence extend back into at least



the 1870's.  The history of these investigations has been reviewed by several



authors, including Stoermer and Yang (1969).  One of the more interesting,



aspects of this historical perspective is that the majority of the studies



undertaken, including some of the very earliest, were in response to some



perceived pollution problem of the day.  This long succession of practically



oriented studies has provided a record of extensive population replacement in



phytoplankton communities, and some indication of change in absolute abundance



of populations and modification of seasonal population dynamics.



     Although there is little doubt that the major factor driving algal



succession in Lake Michigan is phosphorus pollution due to both its primary and



secondary effects, there are undoubtedly other effects which are partially



masked by this overriding factor.  Perhaps the least understood of these is the



effect or effects of increasing conservative ion abundance.  It has long been



recognized that there are striking differences in the algal floras in waters of



different salinities.  It is also very apparent that many of the algal



populations which have invaded the Great Lakes during the past few decades are



characteristically found in high salinity environments.  This  particular



modification is, of course, true not only of algal populations but of consumer



organisms as well.  The actual physiological and/or ecological mechanisms



operating have not been satisfactorily determined.  It is clear, however, that



further modification of the indigenous biota is highly undesirable, and that if

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conservative ion contamination is a major contributory factor, it poses a very



serious problem due to the very long residence times of the Great Lakes and the



difficulty in controlling sources.



     At the present time the most pronounced and complicated effects of



multiple loadings occur in the nearshore waters.  This zone is also the region



of most intensive physical effects.  Local and transient advection regimes may



cause gross variations in the dispersion of pollutants entering the lake and,



as would be expected, the influence of these materials on the algal flora may



be highly variable.  These regions may thus show a long term statistical trend



in population modification but, at any given time, these trends may be



submerged by local effects of transient intensity.



     The present project deals with a limited area of Lake Michigan along the



Indiana coastline.  This region lies within the area of Lake Michigan which has



been extensively modified by factors which affect phytoplankton occurrence and



abundance.  Several qualitatively different local sources are present, and the



effect of these sources on phytoplankton composition and abundance are of



special interest because adjacent regions of the lake are intensively utilized



for both recreational purposes and as a source of potable water.



     The primary objectives of the project, which is part of a more



comprehensive investigation, are the following:



     1.  To determine the composition and abundance of the phytoplankton flora



in comparison with past conditions to the extent that they are known, and



provide firm documentation for comparison with future studies;



     2.  To determine if there are occurrence patterns of specific



phytoplankton physiological group populations which may reflect the effects  of




specific sources;

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     3.  To determine if distribution patterns In the phytoplankton are
oorrelafced with particular chemical or other blotio paramettrs which may
indicate a cause-effect relationship.

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                            MATERIALS AND METHODS
          "X

     The sampling array utilized in this study is shown in Figure 1.  Sampling
was conducted on 11 June, 20 August, and 24 September, 1977.  Four transects
were analyzed with stations located 1/4, 1/2, 1, and 2 miles offshore.  The
eastern-most transect did not have a 2 mile station.  For each station a 2 m
and bottom sample were analyzed.  All samples were collected by the U.S.
Environmental Protection Agency.
     All samples for phytoplankton population analysis were taken as 250 ml
splits of the original 5-liter Niskin Bottle cast.  These subsamples were fixed
with a Lugols solution and stored.  For subsequent analysis, the sample bottles
were agitated and a 50 ml aliquot was removed.  Material was concentrated by
filtration onto 25 mm "AA" Millipore filters, partially dehydrated through an
ethanol series, and embedded in clove oil.  Prepared filters were mounted on a
50 x 75 mm glass slide and covered with a 43 x 50 mm #1 cover glass.
Preparations were kept in a horizontal position and allowed to dry for
approximately two to four weeks, during which time embedding medium lost by
volatization was periodically replaced.  When the filter was completely
cleared, the edges of the cover glasses were sealed with paraffin.
     Slides were analyzed by visual counts of phytoplankton cells present using
Leitz Ortholux microscopes fitted with fluorite oil immersion objectives with a
nominal Numerical Aperature of  1.32. Magnification used for identification and
enumeration was approximately 1200 X.  Population estimates given are the
average of two 10 mm radial strips counted.  Effective filtration diameter in
the filtration apparatus used is 20 mm.
     Raw counts were transformed to computer format on punched cards.   Computer

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                    87 20'
87 10'
8700f
                       LM 01
                                                 LM 02
                                                                                                0LM03
                                                                                    I IND 38
                                                                                                         IND 44
(Jl
                        IND30
                        IND 3i
                        MND32
                                                      IND 37
                                                                                        IND 39
                                                 BURNS  V HARBOR
                                FIG.  1.   Sampling station locations;  southern Lake  Michigan,  1977.

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data summaries are available for all samples counted (see Stoermer and Krels,



in press).  Summaries include estimates of absolute frequency and assooiated



error, and an estimate of relative abundances for individual taxa as well as



major algal divisions.  Assemblage parameters calculated included an estimate



of total phytoplankton abundance and a measure of error associated with the



estimate, an estimate of assemblage diversity (H), and an estimate of the



evenness component of the calculated diversity.  Summary information is stored



on magnetic tape and is available for further data anlysis.



     Various physico-chemical analyses were conducted by the EPA at the time



the samples were collected, and they provided this information to us.  Contour



plots for these data are presented in Appendix Figures 1-33.

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                                   RESULTS








OVERALL ABUNDANCES OF MAJOR ALGAL GROUPS







     Relative and absolute average abundances of major algal groups for a given



cruise are presented in Table 1.  Highest overall densities were attained by



blue-green algae and diatoms, with greens, ehrysophytes, and cryptomonads,



secondarily important.  The undetermined category consists almost entirely of



mioroflagellates which presumably belong to the Haptophyceae (Stoermer and



Sicko-Goad, 1977; Sicko-Goad, Stoermer, and Ladewski, 1977).  Total absolute



abundances for the three cruises are presented in Figure 2,  A total of 288



taxa were identified and recorded.  The average total density for all samples



was 4420 cells/ml, ranging from 844 to 12,078 cells/ml.



     In June, depending on the station, either blue-green algae, diatoms, or



haptophytes were the major group present.  At Gary Harbor, haptophytes were



dominant at the two offshore  stations, with diatoms dominant nearshore.   At



Burns  Harbor, diatoms were the dominant group at all  stations except the  1/2



mile station, where blue-green algae dominated the assemblage.   At  the Indiana



Dunes  transect, diatoms were  the most  numerous at the near- and  offshore



stations, with haptophytes dominant at the  1/2 mile and  1 mile stations,



composing 57  and 50% of the  total  community respectively.   Along the



eastern-most  transect near Michigan City, diatoms were  dominant  at  the two



nearshore  stations, averaging 55%  of the  population,  with  blue-green  algae



dominant at  the  1 mile station,  composing about  38$ of  the  community.  Over  all



 15 stations  in June, diatoms averaged  35.8$ and  blue-green  algae averaged 18,6$



of the total  phytoplankton.

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          TABLE 1.  STATISTICAL SUMMARY OF MAJOR ALGAL GROUPS IN SOUTHERN LAKE MICHIGAN,  1977.
co

June

Blue-greens
Greens
Diatoms
Chrysophytes
Cryptomonads
Dino flagellates
Undetermined
Ave. Relative
Abundance %
18.60
8.01
35.82
8.52
4.99
0.69
22.59
Ave.
Cells/ml
423.49
168.11
780.50
224.38
122.87
13.26
581.26
August
Ave. Relative
Abundance %
51.55
17.37
17.33
1.32
3.41
0.36
5.38
Ave.
Cells/ml
2038.82
697.15
680.53
52.78
136.69
14.10
213.77
September
Ave. Relative
Abundance %
50.48
7.76
23.42
1.92
6.64
0.18
2.61
Ave.
Cells/ml
1683.05
249.93
757.60
59.48
207.91
5.73
82.52

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                                         JUNE  77
                                     20  AUG. 77
FIG.  2.   Seasonal Distribution and Abundance Trends of the Total
Phytoplankton Assemblage.

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     In the August sampling period, blue-green algae were the dominants at all



stations along all four transects.  They ranged from a low of 33$ of the total



algal assemblage at station 33 to 6f% at station 37.  The diatom component



ranged from 9 to 28$ of the total assemblage.  The green algae composed



approximately the same proportion of the community as did the diatoms, ranging



from 12 to 28$.



     In Septembers blue-green algae maintained their dominance.  Only at the 1



mile station off Burns Harbor and Gary Harbor did the diatoms dominate.  Over



all 15 stations, blue-green algae averaged 52% (Table 1) of the total community



and reached a maximum of 5B% at the 1 mile station at Indiana Dunes.  Diatoms



composed 23% of the total and were more numerous at the western-most two



transects, possibly as a response to the higher silica values.







REGIONAL AND SEASONAL TRENDS IN ABUNDANCE OF SELECTED TAXA
                     Hass . (Fig. 3)
     This species occurs in all regions of the Great Lakes, and appears to be



eurytopic.  In southern Lake Michigan, it seemed to be fairly sensitive to



silica levels.  In June, it was found in higher numbers offshore and along the



Gary Harbor transect, where all silica values were above 0.30 mg/1  (Appendix



Fig. 22).  In August, it was present in low densities, not over 30  cells/ml.



It was found at its maximum at the 1/2 mile station off Burns Harbor, with a



silica value of 0,58 mg/1  (Appendix Fig. 23).  This large silica value was



probably the result of an  isolated "slug" of river water derived from Burns
                                       10

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Harbor and entrained in a local circulation gyre.  The effect of this "slug"




was also noted in various other species examined.  Highest abundances of _A.




formosa were present in September, probably related to the higher silica values




present in this month (Appendix Fig. 24).








Cvclotella comeqsj.s (Grun.) V.H. (Fig. 4)




     This species is a relatively recent introduction into Lake Michigan, and




its ecological affinities are not well known.  In Saginaw Bay in 1974, it




appeared in bloom quantities in August, and was still abundant into October




(Stoermer and Kreis, in press).  They also noted that it was able to tolerate




very low levels of silicon.  In southern Lake Michigan, a similar seasonal




effect was present.  It was found in very low numbers in June, but increased




substantially in the August and September sampling periods.  Abundances of this




species appeared to be highest near shore and along the Gary Harbor and Burns




Harbor transects, possibly displaying a high tolerance for more perturbed




areas.  Analysis of variance determined that, in August, densities were




significantly lower (.05 level) at the offshore stations on each transect  than




at the three nearshore stations.  Additionally, significant positive




correlations at the .01 level were found with NO,, NH~, and conductivity  in



both August and September.  However no such  significant correlations  were found



with silica.








Cvclotella crvptica Reimann. Lewin, and Guillard  (Fig. 5)




     This species was originally described  from a  brackish-water  habitat




(Reimann .gi. JLL, 1963).  Most of the  records of  its  occurrence  in Lake Michigan




come from harbors and inshore areas subject  to high  chloride  levels (Stoermer
                                       12

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                                II  JUNE  77
                              20  AUG. 77
FIG.  U.  rtistribution of gvclotella comensis.
                     13

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                                 JUNE 77
                              20  AUG.  77
FIG.  5.  Distribution of Cyclotelja crvp.t4.ca.

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and Yang, 1969).  In southern Lake Michigan, it was found in low numbers in




June and September.  However, in August, it was found in fairly high densities




near shore along the Gary and Burns transects.  A maximum density of 180




cells/ml was found at the 1 2 mile station at Burns Harbor, probably due to the




presence of river water derived from the harbor.  In August, . cryptica was




significantly correlated with conductivity, NO-, Si02, and aerobic heterotrophs.









Cyclotella pseudostelligera Hust. (Fig. 6)




     Populations of this species are usually found in eutrophied areas.  Its




range in the Great Lakes appears to be restricted to harbors and river mouths




(Stoermer and Ladewski, 1976).  It was present in southern Lake Michigan in low




numbers in June and September.  However, in August, it had a distribution




similar to Cyclotella cryptica.  A maximum density was found at the  1/2 mile




station at Burns Harbor once again, where it appears that the  river  water  is




having a great effect on the makeup of the algal community.  High numbers  were




also found at the  1 mile station at Burns Harbor, and the 1/4  mile station at




Gary.  Similar to . cryptica, it also was found to be significantly correlated




with conductivity, NO-, SiO,,, and aerobic heterotrophs in August.








Cyclotella stelligera (Cl. & Grun.) V.H. (Fig. 7)




     This species  has been reported to be intolerant of high levels  of




eutrophication, and is usually removed from regions of the Great Lakes which




have undergone extensive perturbation.  Hohn (1969) reported that its abundance




in Lake Erie has declined since the 1930's.  In southern Lake  Michigan, it was




present in highest numbers in the August and September cruises.  In  August, the
                                        15

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                                      JUNE 77
                                  20  AUG. 77
FIG.  6.  Distribution of Cvolotella pseudostelligera.
                         16

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                              20 AUG. 77
FIG.  7.  Distribution of Cvclotella
                      17

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analysis of variance procedure demonstrated that, at the 5% level of




significance, higher numbers were found at the less disturbed eastern-most two




transects than at Gary or Burns Harbor.  In June and September, no trends were




apparent.  No significant correlations were found for C. stelligera versus any




physico-chemical parameter monitored for the three sampling dates.









Fragilaria crotonensis Kitton (Fig. 8)




     This species is one of the most common plankton diatoms.  It is present in




all the Great Lakes, and can tolerate a wide range of ecological conditions.




As in Saginaw Bay in 1974 (Stoermer and Kreis, in press) densities were  lowest




in August, with only isolated low level populations found.  Highest densities




were recorded in September, with a decreasing offshore  trend apparent.   In this




month it exhibited a significant positive correlation at the .01 level with




conductivity, N0~, NH~, and SiO-.  In June, densities were intermediate  between




August and September values, with no trends evident.









Nitzschia acicularis Win. Sm. (Fig. 9)




     This species is widely distributed in the Great Lakes.  In  southern Lake




Michigan, in June, its distribution was erratic, although it was  found  in




slightly higher numbers at the Burns Harbor transect.   Populations  declined  to




very low numbers in August, similar to the seasonal pattern  observed  in




southern Lake Huron (Stoermer and Kreis,  in press).  Densities increased in




September, attaining their highest values, with  greatest  abundances tending  to




be concentrated along  the nearshore areas and  the  Gary  and  Burns Harbor




transects.   In  September, significant  positive correlations  at the  .01  level




were found with conductivity, NO-, NH-j,  SiO^,  and  aerobic heterotrophs.
                                        18

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                                   JUNE 77
                                20  AUG. 77
FIG.  8.  Distribution of Fragilaria crotonensis.
                       19

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                              I  JUNE  77
                            20 AUG.  77
FIG.  9.  Distribution of NitzsQfria, acicularis.
                    20

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Nitzschia fonticola Grun. (Fig. 10)




     This species has predominantly been recorded from nearshore localities in




the Great Lakes (Stoermer and Yang, 1969).  In June, its distribution was




erratic, with no trends evident.  Its numbers declined in August, and it was




not present at all at the offshore stations.  By September, it attained its




highest densities.  Like N_. acicularis  it  demonstrated a preference for the




nearshore regions and for the Gary and Burns Harbor transects.   In  September,




it was found significantly correlated at the .01 level with N03, NH3, and




aerobic heterotrophs.  Overall, its distribution appears to be fairly similar




to N. acicularis, and it too displays a tolerance for polluted conditions.









Nitzschia palea  (Kutz.) Wm. Sm. (Fig. 11)




      Stoermer and Yang (1969)  noted that most of the  records  for this  species




in Lake Michigan come from polluted harbors and river mouths.  In  this  study,




it reached  its greatest  abundance  in June,  and  displayed definite  affinities




for  the Gary and Burns Harbor  regions.  On  this first cruise,  it was  found to




be significantly correlated at  the  .05  level with N03 and  NH3>   Its numbers




decreased in August  and  September.  Larger  densities  were  found  at the




nearshore stations  than  at  the furthest offshore  station  for  all transects in




the  latter  two months.









Stephanodiscus minutus Grun.  (Fig.  12)




      This  species  has been  reported to  be a winter  dominant in mesotrophic to




eutrophic lakes  (Huber-Pestalozzi,  1942).   In  Lake  Michigan,  Stoermer and Yang




 (1970)  noted  that  it becomes  abundant  in  early spring collections from certain




near and  offshore  localities.   They also  noted that it  was more abundant in
                                        21

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                                I  JUNE  77
                              20  AUG. 77
                               24 SEPT. 77   720
FIG.  10.  Distribution of Nitzschia fonticola.
                    22

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U)

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                                JUNE  77
                             20  AUG. 77
                                                  150
                                            J> /100
                             24  SEPT. 77   /0
FIG.  12.  Distribution of Steohanodiscus minutus.

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1967 than 196U.  In June, in southern Lake Michigan, this species was present




in fairly high numbers, and displayed a preference for the more eutrophied Gary




and Burns Harbor regions.  By August and September, its numbers declined




drastically and it was present in very low numbers at a few stations.








Synedra filiformis Grun. (Fig. 13)




     This species has been recorded mainly from offshore regions in Lake




Michigan, and Stoermer and Kreis (in press), regard it as one of the




characteristic species of the offshore phytoplankton in the upper Great Lakes.




However, Cleve-Euler (1953) noted that it can tolerate brackish water.  In




September, it was found  in greatest abundance in the polluted Gary Harbor




region, and it decreased moving east to Michigan City.  Its abundance was also




found to correlate highly with conductivity, NO.,  and NH, at the  .01 level.




Its numbers were very low in June and August at all stations.








Tabellaria flocculosa var. linearis Koppen  (Fig.  14)




     This species was present at scattered  stations in June.  By  August,  its




numbers declined, similar to the occurrence pattern noted in southern Lake




Huron  (Stoermer and Kreis, in press).  In September, large populations  occurred




at  the two nearshore stations at Gary Harbor (Fig.  14).  Generally,  in




September, offshore densities were lower than they were near shore.   It also




exhibited significant positive correlations with  NO- and SiOp at  the .01  level




in  September.
                                        25

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                                JUNE  77
                             20 AUG. 77
FIG.  13.  Distribution of Svnqflra fijiformia.
                    26

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                                         I  JUNE 77
                                      20  AUG. 77
FIG.  14.  Distribution of Tabellaria flocculosa var. linearis.
                             27

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Chlorophyta








Chlamvdomonas spp. (Fig. 15)




     This green flagellate was a dominant in the system in August, and occurred




only in minimal numbers in June and September.  In August, it displayed highest




densities at the three nearshore stations at Gary and Burns Harbor.  This




species correlated at the .01 level in August with NO., and NH,.  Stoermer j.t




al. (1975) noted that Chlamvdomonas spp. was abundant in some areas of Lake




Ontario, and reached its maximum populations around July.








Scenedesmus spp. (Fig.  16)




     The genus JScjen.ed.esro.us. was found  in  fairly high numbers, and was




represented by a variety of different species.  Most species of Scenedesmus




reported from the Great Lakes prefer  eutrophic waters.  In  southern Lake




Michigan, it was found  in approximately  similar numbers over all three dates




with no trends apparent within a given cruise.  Further substantiating this




lack of habitat preference is the  fact that no significant  correlations were




found when compared to  any physico-chemical parameters.








CrvptoDhvta








Crvptomonas pyata Ehr,-  (Fig.  17)




     This species is very common  in all  regions  of the Great Lakes.   In  this




study, over all three cruises  it  exhibited affinites for  both the nearshore




waters and the Gary and Burns  Harbor regions.   It does not appear to exhibit




any seasonal trends.  In both  August and September,  it correlated highly (.05




level) with conductivity, N0_,  and NH.,.







                                       28

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                                I  JUNE 77
FIG.  16.  Distribution of Scenedesmus spp.
                     30

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                          II JUNE 77
                          20  AUG. 77
FIG.  17.  Distribution of Cryptomon^s oyata.
                     31

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QvanoDhvta








Anabaena flos-aouae (Lyngb.) Breb. (Fig. 18)



     Low levels of this species are found consistently in the Great Lakes;



however, high densities are found only in the more eutrophic regions within the



system.  Stoermer and Kopczynska (196?) found the maximum abundance of J,.



flos-aouae in southern Lake Michigan to be on the same order as in eastern Lake



Ontario.  In this study in June, it was found at only three of the stations



sampled.  By August, it was found scattered in about half of the stations, with



a maximum occurrence at the nearshore station at Indiana Dunes.  In September,



it was found at 10 stations, with no trends apparent.








Anacvstis incerta Dr. & Daily (Fig. 19)



     This species is common in the summer and fall phytoplankton assemblages  in



the Great Lakes.  Stoermer jb. Jti.- (1975) noted that this species is most



successful under conditions of silica depletion.  In the June cruise,  this



species was not present to any significant extent.  By August, it  increased



greatly, and was dominant at every station.  It maintained these high  numbers



into September, and remained as one of the dominants.  No trends could be



detected within the sampling scheme, and this may be due to  its pattern of



indeterminate colonial growth, which causes varying degrees  of error in



abundance estimates.








Qscijlatoria bornetii Zukal  (Fig. 20)



     This species has previously  been reported from Lake Michigan  mainly at  the



thermocline depth during  summer stratification, but rarely in  the  surface
                                       32

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            7
                                 JUNE  77
                              20  AUG. 77
FIG.  18.  Distribution of Anabaena fjos-aquae.
                     33

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                              20 AUG.  77
                                24 SEPT. 77   / 1000
FIG.  19.  Distribution  of Anacvstis jtiQerta.

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waters.  It has only occasionally been found in abundance in the upper Great



Lakes.  In southern Lake Michigan, in June, it was one of the dominants.  It



tended to be in higher densities both nearshore and at the Gary and Burns



Harbor regions.  In August, it decreased in numbers, and only the 1/2 mile



station off Michigan City had an extensive population.  It increased slightly



in September, with highest abundances along the Gary Harbor transect.








Microflagellates








Haptophvte sp. #1 (Fig. 21)




     One group of flagellates which may be playing an increasingly larger role,



especially in the Lake Michigan phytoplankton assemblages, are the



haptophytes.  Little is known about the freshwater ecology of this primarily



marine group.  Chrvsochromulina parva has been reported from both Lake Erie and



Lake Ontario.  Munawar and Munawar (1975) regard it as one of the most



numerically abundant species in the St. Lawrence Great Lakes.  In Lake Ontario,



Stoermer ._. .ai.. (1975) found Chrvsochromulirxa Darya to be abundant, with its



largest populations occurring in June and July.  In southern Lake Michigan,



Haptophyte sp. #1 was a dominant component of the system in June.  Lowest



densities were recorded at the 1/4 mile stations at each transect, and it



appeared as if some type of nearshore inhibition effect was occurring.  Highest



abundances were found along the Gary Harbor and Indiana Dunes transects.



Numbers decreased in August, with abundances lowest at the offshore  stations.



Densities further decreased into September, where this species played  only  a



minor role in the system.
                                       36

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                                  DISCUSSION








     There is no doubt that diatoms as a group have decreased in dominance in




south Lake Michigan since the early 1960's, when Stoermer and Kopczynska (1967)




found them dominant at all stations and all months.  The diatoms that are now




of consequence are typically those species associated with varying degrees of




eutrophication.  Green and blue-green algae are composing larger portions of




the phytoplankton assemblages.  They can outcompete diatoms, especially in the




summer, under conditions of low silica and high temperatures.  In this study,




Anacvstjs incerta was the dominant taxon in both August and September.




Additionally, phytoflagellates are now a major part of the Great Lakes system




(Munawar and Munawar, 1975).




     Within the past 50 years, chloride concentrations have been increasing in




the Great Lakes.  Beeton (1965) noted that chloride levels, along with other




conservative elements, have been increasing in Lake Erie, Lake Ontario, and




Lake Michigan since the early 1900's.  A number of marine and halophilic algal




species have been recorded in the Great Lakes, with most of these reported




within the last twenty years.  Stoermer (1978) noted that most of the




phytoplankton species which have invaded the Great Lakes are halophilic in




nature.  In 1977, the brackish-water species BiddulDhia sp. and Terosinoe




musica were recorded from southern Lake Michigan for the first time  (Wujek,




pers. comm.).  In this study, a variety of salt tolerant forms were  present in




fairly high numbers, including Cvclotella crvptica, Cyclotella




pseudostelligeraf pia^oma tenue var. eloncatum. and Synedra filiformis.  Also,




two species of Skeletonema. a brackish-water genus, were found.  Haptophytes




were found as a dominant in June, and this group appears to be increasing in
                                      38

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abundance in the Great Lakes.




     Aside from the halophilic forms, other species typical of eutrophic waters




were present.  Many of the diatoms found in abundance were species described by




Stoermer and Yang (1969) as tolerating moderately disturbed portions of the




Great Lakes.  Included in this group are Asterionella formosa, Fragilaria




crotonensis. Stephanodiscus alpinus, Stephanodiscus minutus, and Synedra




ostenfeldii.  Other species found in southern Lake Michigan that are common in




disturbed areas include Nitzschia spp., Stephanodiscus hantzschii  and




Stephanodiscus subtilis.  In the green algae, the genus Scenedesmus is common




in eutrophied areas.  It was also noted that, in many instances, those species




which were found to tolerate disturbed waters were found in higher densities at




the Gary Harbor and Burns Harbor regions than at the eastern-most two transects.




     One of the more striking aspects of phytoplankton distribution in the area




of study is the atypically large abundance of species of the genus Nitzschia,




particularly species such as flu palea and other forms which are often found in




areas with extremely degraded water quality conditions.  Cholnoky (1968) and




others have noted that many members of this genus are often associated with




high levels of organic or reduced nitrogen compounds.  Species such as N^. palea




are, in fact, often considered to be indicative of this type of pollution.




Although NH, levels are not extremely elevated at the stations studied, our




data suggest that this type of perturbation may be an important factor in the




area of study.  This hypothesis is further enhanced by the fact that the




occurrence of Nitzschia species reported to be tolerant of organic loadings is




positively correlated with estimates of aerobic heterotroph abundance developed




and furnished to us by the EPA Region V laboratories.




     In the August cruise, with low silicon levels and increased temperatures,
                                       39

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diatoms were found in low densities .  Only Cvclotella comensis and Cvclotella



           were able to thrive under these conditions to any significant
extent.  Both of these species have been reported to be extremely  tolerant  of



low silica levels, and it appears they can outcompete other species when  such



conditions exist.  It is interesting to note that in August, ..  opmensls.  was



found in higher numbers along the more polluted Gary and Burns transects , while



.. stellieera was recorded in greater abundances at the less disturbed



eastern-most two transects.




     The sudden dominance of Pyc^otej.^ comensis. a diatom which ,  so  far  as we



have been able to ascertain, was exceedingly rare in Lake Michigan prior  to



1975 is difficult to interpret.  This species has become an important element



of the flora throughout the lake (GLRD, unpublished data) during the  summer and



fall.  Similar blooms have been noted in Lake Huron (Lowe,  1974; Stoermer and



Kreis, in press).  Although the ecological tolerance of this species  is very



poorly known, it is usually reported from oligotrophic systems which  are  under



some nutrient stress.  Based on data from Lake Huron, the species  is  very



tolerant of low levels of dissolved silica but does not tolerate nitrate



depletion (Stoermer and Kreis, in press).  In Lake Huron it forms  large late



summer and fall blooms in the interface waters of Saginaw Bay  and  Thunder Bay.



It is interesting to note that .. comensis has apparently effectively replaced



.. michiganiana . an indigenous species which was previously a  consistent  summer



dominant in Lake Michigan.  Although there may be several plausible



explanations for this, it would appear that the  superior competetive  ability  of



. comensis may be related to its tolerance of low  silica levels,  and thus



related  to continued phosphorus stress on  the system.



      It  should  be recognized  that ,  due to  the timing  of collections  in the

-------
present study, maximum levels of phytoplankton standing crop were probably not




encountered.  Previous studies have shown that maximum phytoplankton density




and maximum regional differentiation of the flora occur during the spring




thermal bar period.  In most instances, phytoplankton abundance in the




nearshore zone, except in the immediate vicinity of strong sources, is on




average lower, but extremely variable following stratification.  The samples




reported here thus represent a "best case" situation so far as illustrating the




effects of eutrophication and salinification on the phytoplankton flora is




concerned.  It would be reasonable to expect much larger and better defined




trends within the area of study during the spring thermal bar period when the




dispersion of inputs tends to be constrained by the thermal bar.




     Another interesting result of the study is the documentation of the




increasing importance of microflagellates in the Lake Michigan phytoplankton.




In the Great Lakes system, extreme abundance of these organisms is generally




associated with regions which have undergone extensive modification.




Unfortunately the taxonomy of microflagellates in the Great Lakes is very




poorly known since many of them can be identified with certainty only with the




aid of the electron microscope.  Because of their increasing ecological




importance more research should be devoted to determining what entities are




present and to developing techniques whereby reliable population estimates can




be made.




     One of the characteristics which appears to distinguish the phytoplankton




flora of the study area from that of previously studied nearshore localities is




the abundance of filamentous blue-green algae.  Although the Cyanophyta have




become more abundant in the offshore waters of Lake Michigan in the past




decade, the most numerically important forms are generally coccoid species.

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Although these forms are also a dominant element of the phytoplankton flora in




the study area, filamentous species are relatively more abundant than expected.




     Running concurrently with this study was an investigation into the




phytoplankton assemblages of Green Bay (Stoermer and Stevenson, in press).  The




phytoplankton components of both systems are highly comparable.  The dominant




taxa of Green Bay for May, August, and October 1977 included Anacvstis incerta.




yclotel,la comensis, Gloeocystis planctonica. and Rhodomonas minuta.  These




species were also of major importance in southern Lake Michigan in 1977-  Total




densities were higher in Green Bay, averaging 5400 cells/ml, while southern




Lake Michigan averaged only 4400 cells/ml.




     The August sampling period in Green Bay was also dominated by the




Cyanophyte Anacvstis incerta. with Cvclotella comensis the dominant diatom.




Cvclotella stellicera was not present in appreciable numbers in Green Bay,




possibly due to the more perturbed conditions found there than at the




eastern-most two transects of southern Lake Michigan where it was found  in




fairly high abundances.  Phytoflagellates were also of importance in Green Bay




in August.




     In October in Green Bay, similar to the September sampling period in this



study, Anacvstis incerta was still the dominant species at a majority of




stations with diatoms and phytoflagellates secondarily important.  It is



interesting to note that, for all of the sampling dates, the flagellate




composition was very similar.  Species of consequence common to both systems




include:  Qhroomonas spp., Crvptomonas marssonij.r Crvptomonas ovata, Qchromonas




spp., Qchronusnas vallesiaca. Rhodomonas minuta. and undetermined haptophytes.




     In 1971 and 1972, GLRD collected and analyzed samples along the Burns




Harbor transect.  This allowed for the comparison of the phytoplankton
                                        42

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assemblages on a temporal scale.  In June 1971, at the 1/4 mile station, a




plume emerging from Burns Ditch was intersected and a bloom condition of 31,000




cells/ml was recorded.  Diatoms, most of which were Gentries, composed 98$ of




the assemblage.  The plume did not reach the three stations further offshore,




and total numbers averaged only 2500 cells/ml, with Rhizosolenia cracilis the




dominant taxon.  Diatoms as a group were also dominant, averaging 70% of the




phytoplankton component.  In June 1972, diatoms were once again most numerous,




averaging 93$ of the assemblage.  The major taxa included Steohanodiscus tenujs




and . minutus.  In June 1977, the assemblage was different than five and six




years previous.  The blue-green algal filament Oscillatoria bornetii and




undetermined haptophyte species were most numerous.  Diatoms as a group were




still dominant, but only composed 38$ of the assemblage.  Blue-green algae




increased to 23$ of the phytoplankton component, whereas in 1971 and 1972 they




averaged only about 2.5$.  Phytoflagellates as a group increased dramatically




in importance, averaging 31$ of the assemblage in June 1977, while in 1971 and




1972 they averaged only M.2 and 1.5$ respectively.




     The August phytoplankton assemblage in 1977 appeared to have changed from




the earlier studies.  In 1977, the blue-green algae, mainly due to Anacvstjs




incerta. were dominant, while diatoms as a group were most abundant in 1971 and




1972.  In 1971 and 1972, blue-green algae averaged about 23$ (300 cells/ml) of




the assemblage, while in 1977 they averaged about 52$ (2030 cells/ml) off Burns




Harbor.  However, the blue-green algal species present over the three years




were similar, mainly belonging to the genera Anacvstis and Gomphosphaeria.  As




in June, flagellates were found in much higher abundances in 1977 than in the




previous years.  In 1971 and 1972 they averaged 7$ (180 cells/ml) and 1$ (1H




cells/ml) respectively, and increased to 22$ (890 cells/ml) of the assemblage

-------
in 1977.



     In September, blue-green algae were dominant over all three years,



averaging 66$ (1200 cells/ml), 61$ (3500 cells/ml), and 49$ (1660 cells/ml) for



1971, 1972, and 1977 respectively.  Interestingly, Anaqvstis incepta was the



dominant taxon for all three years.  Diatoms composed a larger portion of the



assemblage in 1977 due to the appearance of CycloteHa comensis. a species not



found in the earlier two years.  Once again, flagellates were found in greater



abundances in 1977 (14$), than in 1971 (1$) or 1972 (3$).



     From the analysis of the phytoplankton component over the three years,



some definite assemblage shifts can be noted.  These include:



     1.  An increase in filamentous blue-green algae in 1977;



     2.  An earlier seasonal dominance of blue-green algae in 1977, to the



point that they are found in higher abundances in June, and are dominant in



August;




     3.  Extremely large increases in the flagellate component;



     4.  A decrease in the relative abundance of the diatom component in May



and June, with it now being dominated by Cvclotella comensis and .. stellicera



in the summer months under silica-limited conditions.



     It still appears that the cultural eutrophication of southern Lake



Michigan is continuing, albeit at a slower rate than five to ten years ago.



Under silica-depleted summer conditions, blue-green algae, phytoflagellates,



and low-silica-tolerant diatoms are now the dominant phytoplankters in the



system.  However, those diatom species characterized by Stoermer and Yang



(1969) as thriving only in disturbed habitats are not present in large



abundances in 1977 in southern Lake Michigan, although it is possible that they



may have been present in April and May under thermal bar conditions.

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                                  REFERENCES

Beeton, A. M.  1965.  Eutrophication of the St. Lawrence Great Lakes.
     Limnol. Oceanogr., 10:240-254.

Cholnoky, B. J.  1968.  Die Okologie der diatomeen in Binnengewassern.
     Verlag von J. Cramer, Lehre.  699 pp.

Cleve-Euler, A.  1953.  Die Diatomeen von Schweden und Finnland.  Teil II.
     Arraphidae, Brachyraphidae. Kungl. Svenska Vet. - Akad. Handl., Fjarde
     Serien, 4(1):1-158.

Hohn, M. H.  1969-  Qualitative and quantitative analyses of plankton
     diatoms, Bass Island area, Lake Erie, 1938-1965, including synoptic
     surveys of 1960-1963.  Ohio Biol. Surv., N. S., Vol. 3, No.1.  211 pp.

Huber-Pestalozzi, G.  1942.  Das Phytoplankton des Susswassers, Teil 2,
     2 Halfte.  Diatomeen.  Jn:  Thienemann, A. (Ed.), Die Binnengewasser, Band
     16, pp. 366-549.

Lowe, R. L.  1974.  Environmental requirements and pollution tolerance of
     freshwater diatoms.  EPA-670/4-74-005, 333 pp.

Munawar, M., and I. F. Munawar.  1975.  The abundance and significance
     of phytoflagellates and nannoplankton in the St. Lawrence Great Lakes. 1.
     Phytoflagellates.  Verh. Int. Verein. Limnol., 19:705-723.

Reimann, B. E. F., J. M. Lewin, and R. R. L. Guillard.  1963.  Cvclotella
     crvpfrica. a new brackish water diatom species.  Phycologia, 3(2):76-84.

Sicko-Goad, L., E. F. Stoermer, and B. G. Ladewski.  1977.  A morphometric
     method for correcting phytoplankton cell volume estimates.  Protoplasma,
     93:147-163.

Stoermer, E. F.  1978.  Phytoplankton assemblages as indicators of water
     quality in the Laurentian Great Lakes.  Trans. Amer. Micros. Soc., 97:1-16.

Stoermer, E. F., and E. E. Kopczynska.  1967.  Phytoplankton populations
     in the extreme southern basin of Lake Michigan, 1962-1963, pp. 19-46.
     In;  J. C. Ayers and D. C. Chandler, Studies on the environment and
     eutrophication of Lake Michigan.  Univ. Michigan, Great Lakes Res. Div.,
     Spec. Rep. No. 30.

Stoermer, E. F., and R. G. Kreis.  In press.  Phytoplankton composition and
     abundance in southern Lake Huron.  Univ. Michigan. Great Lakes Res Div.
     Special Report No. 66.  382 pp.

Stoermer, E. F., and T. B. Ladewski.  1976.  Apparent optimal temperatures
     for the occurrence of some common phytoplankton species in southern Lake
     Michigan.  Univ. Michigan, Great Lakes Res. Div. Publ. No. 18.  48 pp.

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Stoermer, E. F., and L. Sicko-Goad.  1977.  A new distribution record for
     Hvmenomonas roseola Stein (Prymnesiophyceae, Coccolithophoraceae) and
     Spiniferomonas triorali? Takahashi (Chrysophyceae,  Synuraceae) in the
     Laurentian Great Lakes.  Phycologia, 16(4):355-358.

Stoermer, E. F., and R. J. Stevenson.  In press.   Green Bay phytoplankton
     composition, abundance, and distribution.

Stoermer, E. F., and J. J. Yang.  19&9.  Plankton diatom assemblages in Lake
     Michigan.  Great Lakes Res. Div., Univ. Michigan, Spec. Rep. No. 47.  268
     pp.

Stoermer, E. F., and J. J. Yang.  1970.  Distribution and relative abundance
     of dominant plankton diatoms in Lake Michigan.  Univ. Michigan, Great
     Lakes Res. Div. Publ. No. 16.  64 pp.

Stoermer, E. F., M. M. Bowman, J. C. Kingston, and A. L. Schaedel.  1975.
     Phytoplankton composition and abundance in Lake Ontario during IFYGL.
     Univ. Michigan, Great Lakes Res. Div., Spec. Rep. No. 53.  373 PP.

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                       BURNS   HARBOR
Appendix Figure 1.  Temperature contours,  southern Lake Michigan;  11  June,  1977.

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OO
                                             BURNS  V HARBOR
                      Appendix  Figure 2.  Temperature contours,  southern Lake Michigan;  20 August,  1977.

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                          BURNS   HARBOR
Appendix Figure 3.  Temperature contours,  southern Lake Michigan;  2U September,  1977.

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VJI
O
                                              BURNS  B HARBOR
                      Appendix Figure M.   Conductivity contours, southern Lake Michigan;  11  June,  1977.

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                  87 20'
87 10'
8 7 00'
VJl
                                              BURNS  K HARBOR
                     Appendix Figure 5.   Conductivity  contours, southern Lake Michigan;  20 August,  1977.

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IM
                                              BURNS  V HARBOR
                     Appendix Figure 6.  Conductivity contours, southern Lake Michigan; 21 September, 1977.

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                 87 20'
                             87 10'
87 00'
u>
.0
                      BURNS  B HARBOR
                  GARY
                       Appendix Figure  7.  Secchi disc contours, southern Lake Michigan;  11 June, 1977.

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                        BURNS  K HARBOR
Appendix Figure 9.  Secchi disc contours,  southern Lake Michigan;  24 September, 1977.

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                  87 20'
87 10'
8700f
CTi
                                              BURNS  I HARBOR
                                                                                                     4140'
                          Appendix Figure 10.   Contours for pH, southern Lake  Michigan; 11 June, 1977.

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                     BURNS  I HARBOR
Appendix  Figure 11.  Contours for pH,  southern Lake Michigan; 20 August,  1977.

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CO
                                             BURNS  V HARBOR
                       Appendix Figure 12.  Contours for pH,  southern Lake Michigan;  24  September, 1977.

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87 20'
87 10'
8 7 00'
      1OB
                      110
                            BURNS  K  HARBOR
     Appendix Figure 13-  Alkalinity contours,  southern Lake Michigan; 11 June,  1977.

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CTl
o
                                              BURNS  V HARBOR
                       Appendix Figure 14.  Alkalinity contours, southern Lake Michigan; 20 August, 1977.

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                         BURNS  I HARBOR
Appendix Figure 15.  Alkalinity contours,  southern Lake Michigan; 24 September,  1977.

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0\
ro
                                              BURNS  V HARBOR
                          Appendix Figure 16.   NO_-N contours, southern Lake  Michigan; 11 June,  1977.

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CO
                                              BURNS  K HARBOR
                         Appendix Figure  17.  NO--N contours,  southern Lake Michigan;  20 August, 1977.

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en
-tr
                                              BURNS  I  HARBOR
                       Appendix Figure  18.  NO--N contours, southern Lake  Michigan; 24 September, 1977.

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ON
VJ1
                                              BURNS   HARBOR
                        Appendix Figure 19.  Ammonia contours,  southern Lake Michigan; 11 June, 1977.

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87 20'
87 10'
87 00'
                                                                                  41 40'
                            BURNS  I HARBOR
      Appendix Figure 20.  Ammonia contours,  southern Lake Michigan;  20 August, 1977.

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                       BURNS  V HARBOR
Appendix  Figure 21.  Ammonia  contours, southern Lake Michigan; 24 September,  1977.

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ON
OO
                                                                            Si02    2m
                                                                           mg/Jt

                                                                              JUNE 1977
                                              BURNS  I HARBOR
                           Appendix  Figure 22.  Silica contours, southern Lake Michigan;  11 June, 1977.

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cr>
10
                                              BURNS  V HARBOR
                         Appendix Figure  23.  Silica contours, southern Lake Michigan;  20 August, 1977.

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                      BURNS  V  HARBOR
Appendix Figure  24.  Silica contours, southern Lake  Michigan; 24 September, 1977.

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                        BURNS  I  HARBOR
Appendix  Figure 25.  Anaerobic  heterotroph contours,  southern Lake Michigan;  11  June,
1977.

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                   87 20'
87 10'
8 7 00'
ro
                                               BURNS  V HARBOR
                     Appendix Figure  26.  Anaerobic heterotroph  contours, southern Lake Michigan;  20 August,
                     1977.

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Appendix Figure 27.  Anaerobic heterotroph contours, southern Lake Michigan;
September, 1977.

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                      BURNS  I HARBOR
Appendix Figure 28.  Turbidity contours,  southern Lake Michigan; 11  June,  1977.

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                 87*20'
87IO'
8700'
Ul
                                            BURNS  I HARBOR
                       Appendix Figure 29.  Turbidity contours,  southern Lake Michigan; 20 August, 1977.

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                        BURNS  V HARBOR
Appendix Figure 30.  Turbidity contours, southern  Lake Michigan; 24 September, 1977.

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87 20'
87 IO1
87 OO1
                                                                                  41 40'
                            BURNS  I HARBOR
     Appendix Figure 31.   Fecal coliform contours,  southern Lake Michigan,  11 June, 1977.

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                 87 201
87M 0'
87OO!
co
                                             BURNS  I HARBOR
                    Appendix Figure 32.  Fecal coliform contours, southern Lake Michigan, 20 August, 1977.

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VO
                                              BURNS  1 HARBOR
                   Appendix Figure 33.  Feoal coliform contours, southern Lake Michigan,  21 September, 1977.

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APPENDIX TABLE 1.  Summary of phytoplankton species occurrence in the near-surface waters of southern
Lake Michigan during 1977 sampling season.   Summary is based on all samples analyzed.  Summary includes
the total number of samples in which a given taxon was noted, the average population density (cells/ml),
the average relative abundance (% of assemblage), the maximum population density encountered (cells/ml),
and the maximum relative abundance (% of assemblage) encountered.

# Average

CYANOPHYTA
Anabaena flos-aquae (Lyngb.) Breb.
Anabaena sp.
Anabaena spp.
A. subaylindriaa Borge
Anaaystis incerta (Lemm. ) Dr. and Daily
A. thermalis (Menegh.) Dr. and Daily
Daatyloaooaopsis rhaphidioides Hansg .
Gomphosphaeria aponina Kutz,
G, lacustris Chod.
Miorocoleus spp.
Oscillatoria bornetii Zukal
0. retzii Ag.
Osaillatoria sp.
Osaillatoria spp.
Sehizothrix sp.
Sehizothrix spp.
Total for division (16 spt.-ies)
CHLOROPHYTA
Ankistrodesmus falcatus (Corda) Ralfs
A. gelifactum (Chod.) Bourr.
Ankistrodesmus sp. #3
Ankistrodesmus sp. #6
Ankistrodesmus sp.
Ankistrodesmus spp.
Ankyra spp.
Chlamydomonae sp.
Chlamydomonas spp.
Coelastrum sp.
Cosmarium sp.
Cosmarium spp.
Cruaigenia irregularis Wille
C, quadrata Morren
C. rectangularis (A. Braun) Gay
C. tetrapedia (Kirch.) West and West
Dictyosphaerium ehr&nbergianum Naegeli
Elakatothrix gelatinosa Wille
slides

29
1
1
3
70
62
27
5
33
1
61
2
12
17
11
8


28
4
14
3
1
64
1
26
22
2
12
7
13
25
9
3
1
7
cells/ttl

24.458
0.372
0.419
0.605
1435.488
86.288
2.397
2.653
226.078
1.257
275.063
2.048
4.328
5.050
0.698
0.768
2067.968

1.862
0.186
0.652
0.140
0.047
9.401
0.047
107.930
64.903
0.559
0.419
0.209
3.002
11.380
2.234
0.559
1.443
0.396
7, pop

0.640
0.012
0.011
0.009
27.888
1.844
0.060
0.071
3.366
0.035
7.683
0.048
0.063
0.088
0.012
0.024
41.854

0.059
0.006
0.017
0.004
0.001
0.195
0.001
1.443
1.620
0.011
0.006
0.007
0.056
0.208
0.028
0.011
0.022
0.005
Maximum
cells/ml

335.103
33.510
37.699
33.510
5443.328
295.309
23.038
62.832
1748.819
113.097
1283.863
94.248
94.248
169.646
14.661
27.227


18.850
4.189
12.566
6.283
4.189
56.549
4.189
1212.654
772.831
33.510
6.283
4.189
69.115
167.551
35.605
33.510
129.852
12.566
% pop

7.045
1.047
1.030
0.391
"63.185
8.338
0.654
1.507
21.305
3.125
36.015
3.197
1.752
3.024
0.308
0.921


0.661
0.180
0.282
0.157
0.121
1.044
0.122
12.725
16.698
0.838
0.078
0.192
0.972
4.676
0.495
0.495
2.016
0.176
                                                                                             (continued).
                                                      60

-------
APPENDIX TABLE 1 (continued).

Franaeia droesaheri (Lemm.) G. M. Smith
Gloeoaystis planatoniaa (W. and W. ) Leram.
Golenkinia radiata (Chod.) Wille
Kirchneriella contorta (Schmidle) Bohlin
K. elongata G. M. Smith
K. lunaris (Kirch.) Moebius
Kivahneriella sp.
Kirchneriella spp.
K. subsolitaria G. *S. West
Lagerheimia ailiata (Lag.) Chod.
L. subsalsa Lemm.
Miaraatinium sp.
Mougeotia sp.
Mougeotia sp. #1
Mougeotia spp.
Nepkfoaytium agardhianum NSg.
M, obesum West and West
Nepkroaytium sp.
Nephrocytiwn spp.
Ooaystis pusilla Hansg.
Ooaystie sp.
Osaystis spp.
Pediastmm duplex Meyen
P. duplex var. alathratum (A. Braun) Lag.
P. obtueum Lucks
P. simplex var. duodenarium (Bailey) Raben.
P. tetras (Ehr.) Ralfs
Pedinamonas minutissima Skuja
Quadrigula sp.
Soenedesmus aauminatus (Lag.) Chod.
S. acutus f. costulatus (Chod.) Uherkov.
S. aautus Meyen
S. avauatus Lemm.
S. armatus var. boglariensis Hortob.
S. biaaudatus (Hansg.) Chod.
5. bijuga var. alternans (Relnsch) Hansg.
S. bijuga (Turp.) Lag.
5. brasiliensis Bohlin
S. carinatus (Leiran. ) Chod.
#
slides
7
86
2
4
23
1
4
19
1
12
2
1
12
1
5
7
1
2
2
1
1
61
3
1
1
1
7
2
1
26
4
4
3
2
1
1
9
2
2
Average
cells/ml
0.186
123.545
0.093
0.326
1.769
0.186
0.140
1.443
0.093
0.512
0.093
0.745
0.908
0.279
0.559
0.908
0.093
0.279
0.209
0.582
0.023
30.881
1.978
0.186
0.186
0.512
1.373
0.349
0.047
4.049
0.745
0.349
0.326
0.186
0.047
0.186
1.001
0.279
0.186
% pop
0.004
3.168
0.002
0.011
0.039
0.003
0.004
0.041
0.002
0.011
0.002
0.006
0.021
0.026
0.017
0.022
0.003
0.003
0.007
0.013
0.001
0.567
0.036
0.005
0.004
0.014
0.036
0.011
0.001
0.099
0.019
0.009
0.008
0.003
0.001
0.002
0.038
0.007
0.003
Maximum
cells/ml
4.189
513.126
6.283
18.850
23.038
16.755
6.283
20.944
8.378
8.378
6.283
67.021
10.472
25.133
18.850
23.038
8.378
16.755
12.566
52.360
2.094
263.894
92.153
16.755
16.755
46.077
33.510
27.227
4.189
41.888
16.755
8.378
12.566
8.378
4.189
16.755
41.888
16.755
8.378
% pop
0.088
8.687
0.156
0.542
0.539
0.312
0.181
0.663
0.220
0.208
0.188
0.555
0.327
2.299
0.587
0.635
0.294
0.176
0.446
1.174
0.055
3.002
1.686
0.463
0.378
1.283
0.790
0.851
0.130
0.932
0.719
0.251
0.330
0.130
0.099
0.176
1.204
0.455
0.202
                                                                                            (continued).
                                                      81

-------
APPENDIX TABLE 1 (continued).

SaenedeemuB diapav BrSb.
5. quadriaauda (Turp.) Brlb.
B, quadriaauda var. longiepina (Chod.) G.M.
SaenedeemuB sp.
SaenedeemuB apinosue Chod.
SaenedeemuB spp.
Sohroederia sp.
SelenastTwn sp.
Selenaetvwn spp.
Stauraetrum sp.
Tetraedrom aaudatum (Corda) Hansg.
7. minimum (A. Braun) Hansg.
r. regulars Kuetzing
Ulotkrix sp.
Undetermined green colony
Undetermined -green filament
Undetermined green filament #5
Undetermined green Individual
Total for Division (75 species)
BACILLARIOPHYTA
Aahnanthee alevei Grun.
A. lanaeolata (Brfib.) Grun.
A. minutissima (KUtz.)
A. veaurvatal
Aahnanthee sp.
AahnantheB spp.
Amphipleura pelluaida KUtz.
Amphora negleeta Stoerm. and Yang
A. ovalis var. pediaulue (KUtz.) V. H.
A. ovalis KUtz.
A. perpueilla Grun.
Amphora spp.
Amphora eubaostulata Stoerm. and Yang
Aeterionella formosa Hass.
Cooooneis plaaentula Ehr.
Coeaoneia sp. #2
ft
slides
1
54
Smith 18
1
12
73
1
2
2
2
4
30
1
2
3
1
9
77


9
2
3
6
7
2
27
1
1
3
24
1
2
81
1
1
Average
cells/ml
0.093
8.866
2.560
0.047
0.884
17.686
0.023
0.070
0.116
0.047
0.116
1.280
0.023
0.628
0.489
0.093
9.634
13.008
436.857

0.233
0.047
0.070
0.233
0.209
0.047
1.629
0.047
0.023
0.070
0.698
0.023
0.047
22.131
0.023
0.023
% pop
0.003
0.227
0.114
0.001
0.020
0.454
0.000
0.002
0.004
0.001
0.003
0.027
0.000
0.011
0.013
0.003
0.188
0.349
9.392

0.005
0.001
0.002
0.007
0.005
0.002
0.032
0.001
0.001
0.002
0.019
0.001
0.001
0.531
0.000
0.003
Maximum
cells/ml
8.378
58.643
25.133
4.189
8.378
92.153
2.094
4.189
8.378
2.094
4.189
14.661
2.094
37.699
23.038
8.378
259.705
90.059


4.189
2.094
2.094
10.472
4.189
2.094
16.755
4.189
2.094
2.094
4.189
2.094
2.094
182.212
2.094
2.094
% pop
0.235
1.802
2.978
0.060
0.234
2.730
0.017
0.121
0.278
0.033
0.100
0.326
0.041
0.589
0.662
0.231
6.263
3.640


0.098
0.041
0.071
0.289
0.118
0.095
0.350
0.117
0.075
0.087
0.248
0.052
0.060
3.413
0.022
0.248
                                                                                            (continued).
                                                    82

-------
APPENDIX TABLE 1 (continued).
#
slides
Cyalot&lla atomus Hust.
C. aomensis Grun.
C. oamensis auxospore
C. aomta auxospore
C. oomta (Ehr.) KUtz.
C. cryptica Reimann, Lewin, and Guillard
C, kutzingiana Thw.
C. meneghiniana K(ltz.
C. meneghiniana var. plana Fricke
C. michiganiana Skv.
C. oeellata Pant.
C. pseudostelligera Hust.
Cyalotella sp. #1
Cyalotella sp. #6
Cyclotella spp.
Cyalotella etelligera (Cl. and Grun.) V. H.
Cymatopleura elliptiaa (Breb. and Godey) Wm. Smith
C. eolea (Br6b. and Godey) Wm. Smith
Cymbella mieroaephala Grun.
C. prostrata var. auerswaldii (Rabh. ) Reim.
Cymbella sp. #12
Cymbella sp.
Cymbella spp.
Diatoma ehrenbergii KUtz.
D. hiemale var. mesodon (Ehr.) Grun.
Diatoma sp.
Diatoma spp.
Diatoma tenue Ag.
>. tenue var. elongatwn Lyngb.
0. tenue var. paahyaephala Grun.
D. vulgare Bory
Diploneis oaulata (Breb.) Cl.
Entomoneis ornata (J. W. Bail.) Reim.
Fragilaria oapuoina Desm.
F. conetruens (Ehr.) Grun.
F. aonatruens var. binodis (Ehr.) Grun.
f. conetruene var. aapitata Herib.
F. construens var. minuta Temp, and Per.
10
90
24
15
61
49
9
17
31
25
50
44
1
45
58
90
1
7
6
4
2
2
2
7
1
1
1
10
29
38
1
5
2
4
1
1
1
13
Average
cells/ml
0.279
86.754
1.117
1.257
5.027
7.330
0.209
0.559
1.466
0.931
3.537
3.863
0.023
7.493
7.912
191.845
0.023
0.163
0.256
0.093
0.047
0.047
0.047
0.209
0.023
0.023
0.023
0.489
2.630
5.818
0.023
0.116
0.047
2.118
0.070
0.023
0.023
0.512
7. pop
0.007
1.930
0.024
0.030
0.096
0.186
0.007
0.018
0.048
0.025
0.072
0.121
0.001
0.189
0.225
5.172
0.000
0.004
0.008
0.003
0.002
0.000
0.002
0.007
0.001
0.000
0.001
0.013
0.086
0.208
0.001
0.004
0.002
0.060
0.002
0.001
0.001
0.014
Maximum
cells/ml
4.189
418.879
14.661
16.755
54.454
180.118
2.094
6.283
33.510
8.378
23.038
23.038
2.094
62.832
56.549
456.578
2.094
2.094
8.378
2.094
2.094
2.094
2.094
4.189
2.094
2.094
2.094
16.755
31.416
41.888
2.094
2.094
2.094
98.436
6.283
2.094
2.094
10.472
% pop
0.094
5.347
0.228
0.395
0.473
4.245
0.095
0.496
1.084
0.271
0.448
0.993
0.058
1.806
1.526
13.582
0.029
0.073
0.348
0.090
0.074
0.022
0.090
0.146
0.088
0.037
0.057
0.483
0.916
1.985
0.060
0.078
0.095
2.833
0.188
0.059
0.049
0.199
                                                                                             (continued).
                                                    83

-------
APPENDIX TABLE 1 (continued).
# Average

Fragilaria aonstruens var. venter (Ehr.) Grun.
F. arotonensis Kitton
F. intermedia Grun.
F. intermedia var. fallax (Grun.) A. Cl.
F. pinnata Ehr.
Fvagi tafia s p .
Fragilaria spp.
Fragilaria vaucheriae (KUtz.) Peters.
Gomphonema dichotonam Kutz.
Gamphonema sp.
Gomphonema spp.
Mastogloia spp.
Melosira granulata var. angustissima 0. Miill.
M. granulata (Ehr.) Ralfs
M. islandiaa 0. Miill.
M. italioa (Ehr.) Kiitz.
M. vafians Ag.
Naviaula angliea var. signata Hust.
N. angliea var. subsalsa (Grun.) Cl.
N. aapitata Ehr.
N. aapitata var. luneburgensis (Grun.) Patr.
N. aostulata Grun.
N. aryptoaephala var. veneta (Kiitz.) Rabh.
N. cryptoaephala Kiitz.
N. decussis 0str.
N. exiguiformis Hust.
N. gastriformis Hust.
N. luzonensis Hust.
N. menisculus var. obtusa Hust.
N. meni.ssu.lu8 var. upsaliensis Grun.
N. platystona var. pantoasekii Wislouchand
Kolbe
N. pupula KUtz
N. pupula var. mutata (Krasske) Hust.
N. radiosa var. tenella (Brgb.) Grun.
ff. radiosa Kutz
Naviaula sp. #19
Naviaula sp. #48
Naviaula sp. #78
slides
1
77
13
10
8
14
7
10
1
2
1
1
13
27
15
57
1
1
24
20
6
1
6
3
5
10
1
1
4
2
1
7
3
5
1
1
1
1
cells/ml
0.023
99.530
6.260
3.398
1.978
0.559
0.628
0.396
0.047
0.047
0.047
0.023
1.466
10.193
1.489
10.000
0.047
0.023
0.908
0.605
0.256
0.047
0.163
0.070
0.116
0.233
0.023
0.023
0.093
0.047
0.023
0.163
0.070
0.140
0.023
0.023
0.023
0.023
% pop
0.001
2.403
0.158
0.124
0.046
0.010
0.012
0.014
0.001
0.001
0.001
0.000
0.038
0.213
0.041
0.302
0.001
0.000
0.033
0.016
0.004
0.000
0.006
0.001
0.002
0.005
0.001
0.000
0.002
0.001
0.000
0.004
0.001
0.005
0.000
0.000
0.000
0.001
Maximum
cells/ml
2.094
397.935
92.153
100.531
75.398
8.378
25.133
6.283
4.189
2.094
4.189
2.094
23.038
167.551
27.227
56.549
4.189
2.094
10.472
4.189
6.283
4.189
4.189
2.094
2.094
2.094
2.094
2.094
2.094
2.094
2.094
2.094
2.094
4.189
2.094
2.094
2.094
2.094
% pop
0.065
8.955
2.564
3.493
2.260
0.131
0.343
0.285
0.060
0.035
0.099
0.035
0.662
2.500
0.750
1.985
0.088
0.026
0.496
0.151
0.118
0.045
0.151
0.049
0.073
0.068
0.058
0.045
0.052
0.049
0.041
0.075
0.060
0.176
0.043
0.022
0.020
0.049
                                                                                            (continued).
                                                    84

-------
APPENDIX TABLE 1 (continued).
# Average

Naviaula sp.
Naviaula spp.
Naviaula subhamulata Grun.
fl. tripunotata (0. F. Mull.) Bory
N. viridula (KUtz.) KUtz.
Neidium dubium fo. constrictum Hust.
N. dubium var. #1
Neidium sp.
Neidium sp. #3
Neidium spp.
Nitzeahia aaiaularis (KUtz.) Win. Smith
N. aauta Hantz.
N. amphibia Grun.
N. angustata var. aauta Grun.
N. baaata Hust.
N. aonfinis Hust.
N. dissipata (KUtz.) Grun.
N. fontiaola Grun.
If. frustulum (KUtz.) Grun.
N. graailis Hantz.
N. kutzingiana Hilse
N. linearis Wm. Smith
N. luzonensis Hust.
If. palea (KUtz.) Wm. Smith
N. paleaaea Grun.
N. reata Hantz.
N. romana Grun.
Nitzsahia sp. #1
Nitzsahia sp. #8
Nitzsahia sp. #9
Nitzsahia spiauloides Hust.
Nitzsahia spp.
Nitzsahia sublinearis Grun.
N. tryblionella Hantz.
Opephora sp.
Plagiotropis lepidoptera var. probosaidea
(Cl.) Reim.
Rhizosolenia eriensis H. L. Smith
R. graailis H. L. Smith
slides
6
50
1
2
1
1
1
2
3
3
76
12
1
1
39
60
16
75
9
5
36
11
1
75
3
17
1
18
1
13
9
75
2
2
1
1
57
48
cells/ml
0.140
2.397
01023
0.047
0.023
0.023
0.023
0.279
0.070
0.349
18.919
0.326
0.023
0.047
3.956
4.026
0.535
14.032
0.977
0.209
3.933
0.326
0.023
17.127
0.256
0.582
0.023
0.791
0.070
2.653
0.559
20.060
0.093
0.047
0.023
0.023
12.520
5.329
% pop
0.003
0.068
0.001
0.001
0.001
0.001
0.000
0.003
0.001
0.003
0.474
0.008
0.001
0.000
0.107
0.120
0.016
0.389
0.047
0.006
0.107
0.008
0.000
0.493
0.006
0.025
0.000
0.026
0.002
0.094
0.024
0.583
0.003
0.001
0.000
0.001
0.289
0.179
Maximum
cells/ml
2.094
43.982
2.094
2.094
2.094
2.094
2.094
16.755
2.094
16.755
85.870
4.189
2.094
4.189
46.077
18.850
8.378
54.454
27.227
4.189
43.982
4.189
2.094
104.720
14.661
8.378
2.094
14 . 661
6.283
64.926
16.755
113.097
6.283
2.094
2.094
2.094
81.681
46.077
% pop
0.050
1.528
0.068
0.033
0.052
0.068
0.045
0.210
0.068
0.139
1.898
0.130
0.049
0.044
1.374
0.746
0.248
2.358
1.241
0.131
1.148
0.130
0.026
3.639
0.348
0.993
0.022
0.423
0.142
2.256
0.542
4.049
0.264
0.068
0.035
0.049
1.859
1.707
                                                                                            (continued).
                                                      85

-------
APPENDIX TABLE 1 (continued).

t Average

Rhoieosphenia curvata (Kutz.) Grun.
Skeletonema potamos (Weber) Hasle
Skeletonema sp.
Skeletonema spp.
Stephanodisaus alpinus Hust.
S. bindevanus (Ktitz.) Krieger
S. hantzsahii Grun.
S. minutus Grun.
S. niagarae Ehr.
Stephanodisaus sp. #5
StephanodiscuB sp. #6
Stephanodisaus sp. #8
Stephanodiscus sp.
Stephanodisaus spp.
Stephanodisaus subtilis (Van, Goor) A. Cl.
S. tenuis Hust.
Surirella augusta Klitz.
S. biser-iata var. bifrons (Ehr.) Hust.
5. ovata Kutz.
S. ovata var. afriaana Hust.
Synedra deliaatissima var. angustissima Grun.
S. filiformis Grun.
S. minusaula Grun.
S. ostenfeldii (Krieger) A. Cl.
Synedra spp.
Synedra ulna var. ahaseana Thomas
Tabellaria fenestrata (Lyngb.) KUtz.
T. floeaulosa var. UneavLs Koppen
Undetermined centric diatom sp. #1
Undetermined centric diatom spp.
Total for Division (160 species)
CHRYSOPHYTA
Ckpysooosous dokidophorus Pasch 
Dinobfyon aysts
D. divergens Imhot
Dinobfyon sp.
Dinobruon spp.
slides
2
5
3
7
59
4
42
85
3
3
1
2
2
39
33
22
14
1
1
1
27
85
67
52
8
33
13
82
22
9


38
66
35
12
63
cells /ml
0.047
0.535
0.209
0.791
9.145
0.396
2.769
29.438
0.070
0.070
0.023
0.047
0.047
2.583
4.235
0.861
0.489
0.023
0.023
0.047
1.838
36.861
16.080
8.843
0.233
12.450
1.443
121.893
16.546
0.814
876.994

3.467
6.888
15.661
1.838
12 . 008
% pop
' 0.001
0.007
0.003
0.019
0.294
0.013
0.081
1.034
0.002
0.002
0.001
0.001
0.001
0.078
0.186
0.028
0.016
0.001
0.001
0.00-1
0.060
0.953
0.484
0.309
0.007
0.409
0.043
2.254
0.468
0.028
22.509

0.096
0.203
0.337
0.050
0.372
Maximum
cells/ml
2.094
31.416
12.566
35.605
69.115
18.850
20.944
154.985
2.094
2.094
2.094
2.094
2.094
33.510
94.248
10.472
8.378
2.094
2.094
4.189
14.661
297.404
94.248
50.265
4.189
75.398
41.888
927.816
314.159
14.661


23.038
48.171
217.817
35.605
136.136
% pop
0.035
0.335
0.131
0.853
1.989
0.614
1.387
9.926
0.073
0.065
0.049
0.087
0.060
1.047
6.716
0.746
0.262
0.066
0.073
0.133
0.528
9.368
2.749
2.219
0.228
3.327
1.206
10.886
8.322
0.796


0.719
1.500
3.665
0.964
3.382
                                                                                            (continued).
                                                      86

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APPENDIX TABLE 1 (continued).
# Average

Mallomonas pseudooorotia'Ui Presc.
Mallomonas sp.
Mallomonas spp.
Oshfomonas sp. #4
Ochpomonas sp.
Oahromonas spp.
Spinifefomonas sp.
Tr-ibonema spp.
Uroglenopsis spp.
Total for Division (14 species)
CRYPTOPHYTA
Chvoomonas spp.
Cryptomonas marssoni-i Skuja
(7. ovata Ehr.
Cvyptomonas sp.
Cryptomonas spp.
Rhodomonas minuta Skuja
fl. minuta var. nannoplanotiaa Skuja
Total for Division (7 species)
PYRROPHYTA
Cerat-ium hirundinella (0. F. Mull.) Shrank
Ceratium sp.
Glenodinium sp.
Glenodin-iwm spp.
Gyrrmodiniwn sp.
Gymnodini-wn sp.
Gyrnnodi.ni.um spp.
Peridinium sp.
Peridin-iwn spp.
Unidentified dinof lagellate sp.
Unidentified dinof lagellate spp.
Total for Division (11 species)
slides
29
3
3
31
1
89
1
1
1


89
22
90
1
60
90
34


7
5
2
2
10
1
3
22
42
22
7

cells/ml
1.559
0.209
0.163
15.778
0.023
147.793
0.023
0.186
0.698
206.297

68.602
1.280
28.647
0.023
5.282
150.656
8.540
263.031

0.186
0.116
0.070
0.047
0.465
0.023
0.163
1.094
5.608
1.745
0.419
9.937
% pop
0.040
0.006
0.003
0.378
0.001
3.561
0.001
0.008
0.029
5.084

1.672
0.025
0.678
0.000
0.131
3.408
0.266
6.180

0.004
0.003
0.002
0.001
0.009
0.001
0.004
0.023
0.200
0.037
0.013
0.298
Max imum
cells/ml
12.566
14.661
10.472
337.197
2.094
1145.633
2.094
16.755
62.832


196.873
18.850
98.436
2.094
23.038
846.135
83.776


4.189
2.094
4.189
2.094
12.566
2.094
6.283
18.850
41.888
23.038
8.378

% pop
0.569
0.427
0.151
10.502
0.060
27.187
0.073
0.697
2.641


4.578
0.624
2.766
0.026
0.760
16.515
3.442


0.086
0.061
0.143
0.061
0.245
0.061
0.181
0.495
2.635
0.573
0.228

                                                                                            (continued).
                                                     87

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APPENDIX TABLE 1 (continued).
                                                                  Average
                                                  slides     cells/ml     % pop
                                                                                            Maximum
                                   cells/ml    7. pop
EUGLENOPHYTA
Phacus sp.
Total for Division  (1 species)
 1         0.023      0.001
           0.023      0.001
                                      2.094    0.066
UNDETERMINED
Undetermined haptophyte  sp.  #1
Undetermined haptophyte  sp.  #2
Undetermined colony  sp.  #2
Undetermined flagellate  spp.
Total  for Division  (4  species)
85
80
34
88
292.841
 16.173
 20.688
229.242
558.944
 8.793
 0.447
 0.529
 4,912
14.681
1866.105   56.974
 106.814    3.380
 134.041    4.597
 772.831   13.503
                                                       88

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                                   TECHNICAL REPORT DATA
                            (Please read Instructions on the reverse before completing)
1. REPORT NO.
   EPA-905/3-79-001
                              2.
                                                           3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
   Phytoplankton Assemblages  of the Nearshore Zone of
   Southern Lake Michigan
             5. REPORT DATE
                  March 1979
             6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
   Eugene P. Stoerroer & Marc  L.  Tuchman
                                                           8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
   Great Lakes Research    Division
   University of Michigan
   Ann Arbor, Michigan   ^8109
                                                           10. PROGRAM ELEMENT NO.
                         2 BA 6k5
              11. CONTRACT/GRANT NO.
               Grant - R005337-01
12. SPONSORING AGENCY NAME AND ADDRESS
   Great Lakes Surveillance    Research Staff
   Great Lakes National Program Office
   U.S.  Environmental Protection Agency
   Chicago, Illinois  60605
              13. TYPE OF REPORT AND PERIOD COVERED
                 Final
              14. SPONSORING AGENCY CODE
                EPA - GLNPO
               Great Lakes National  Program
                  Office
15. SUPPLEMENTARY NOTES
16. ABSTRACT
   Phytoplankton samples  from  nearshore stations along the  Indiana coast of Lake
   Michigan were analyzed  to determine the composition and  seasonal  abundance of
   Phytoplankton populations.   Occurrence patterns of major populations and popu-
   lation groups were  inspected.   As might be expected in a local  inshore region
   where physical mixing  and advection processes are relatively  intense, phyto-
   plankton distribution  is highly variable.  The largest general  effect noted is a
   continuing increase  in  groups  other than diatoms, apparently  as a result of silica
   depletion.  The singular exception to this trend is the  abundant  occurrence of
   Cyclotella comensis, a  diatom  which has only recently become  abundant fn Lake
   Michigan and can apparently tolerate very low silica  levels.   Specific to the
   region is an atypically high abundance of members of  the diatom genus N^tzschjj
   during some sampling periods.   High abundance of these organisms  appears to be
   associated with organic nitrogen and ammonfa inputs.  Occasional  occurrences of
   populations such as Thai assiosi ra sp. and Skeletonema spp.  were  noted  and may
   be indicative of local  areas of high conservative ion input.   Another character-
   istic of the phytoplankton  assemblages in the Indiana nearshore region is the
   high abundance of microflagellates, especially organisms which apparently belonging
   to the ffaptophyceae or  Prasinophyceae,
                                KEY WORDS AND DOCUMENT ANALYSIS
                  DESCRIPTORS
                                              b.lDENTIFIERS/OPEN ENDED TERMS  C. COSATI Field/Group
   phytoplankton populations
   water quality, microflagellates,  monitor-
   ing,  nitrogen, phosphorus, silica
  Southern Lake  Michigan
  Indiana Nearshore
 8. DISTRIBUTION STATEMENT
  Available through
  Springfield, VA   22161
19. SECURITY CLASS (ThisReport)
    Unclass ified
                           21. NO. OF PACES
20. SECURITY CLASS (ThispageJ
    Unclass ified
                           22. PRICE
EPA Form 2220-1 (Rev. 4-77)   PREVIOUS EDITION is OBSOLETE
                                              89
                                                                       U S GOVERNMENT PRINTING OFFICE 826-681

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