EPA-600/3-76-095
October 1976
Ecological Research Series
BIOLOGICAL, CHEMICAL AND PHYSICAL
RELATIONSHIPS IN THE STRAITS OF MACKINAC
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal
species, and materials. Problems are assessed for their long- and short-term
influences. Investigations include formation, transport, and pathway studies to
determine 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-600/3-76-095
October 1976
BIOLOGICAL, CHEMICAL AND PHYSICAL RELATIONSHIPS IN
THE STRAITS OF MACKINAC
by
Claire L. Schelske, Eugene F. Stoermer,
John E. Gannon and Mila S. Simmons
Great Lakes Research Division
University of Michigan
Ann Arbor, Michigan 48109
Grant R802721
Project Officer
Nelson 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-Duluth,
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.
ii
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FOREWORD
Our nation's freshwaters are vital for all animals and plants, yet our
diverse uses of water for recreation, food, energy, transportation, and
industry physically and chemically alter lakes, rivers, and streams. Such
alterations threaten terrestrial organisms, as well as those living in water.
The Environmental Research Laboratory in Duluth, Minnesota develops methods,
conducts laboratory and field studies, and extrapolates research findings
—to determine how physical and chemical pollution affects aquatic
life
—to assess the effects of ecosystems on pollutants
—to predict effects of pollutants on large lakes through use of models
—to measure bioaccumulation of pollutants in aquatic organisms that
are consumed by other animals, including man
This report, part of our program on large lakes, details our findings
in the Straits of Mackinac, that waterway connecting Lake Michigan and Lake
Huron.
Donald I. Mount, Ph.D.
Director
Environmental Research Laboratory
Duluth, Minnesota
111
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CONTENTS
List of Figures ix
List of Tables xiii
Acknowledgments xv
I Introduction 1
1.1 Objectives 1
1.2 Current Patterns in the Straits Region 2
1.3 Description of the Study Area 4
1.4 Literature Cited 8
II Conclusions 10
III Description of Physical-Chemical Conditions and Phyto-
plankton Community Parameters. C. L. Schelske,
M. S. Simmons and L. E. Feldt 14
3.1 Methods and Materials 14
Shipboard analyses 14
Laboratory analyses 16
3.2 Epilimnetic Averages and Seasonal Variation 17
Water temperature 17
Specific conductance 20
Hydrogen ion concentration 21
Secchi transparency 21
Chlorophyll a 21
Soluble reactive silica 21
Nitrate nitrogen 22
Total phosphorus 22
3.3 Physical-Chemical Conditions in August 23
Water temperature 23
Specific conductance 24
Hydrogen ion concentration 24
Silica 24
3.4 Physical-Chemical Conditions in September 25
Water temperature 25
Specific conductance 26
Hydrogen ion concentration 26
Silica 26
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3.5 Physical-Chemical Conditions in October
Water temperature
Specific conductance
Hydrogen ion concentration .............
Silica ....................... 28
3.6 Correlation of Physical, Chemical and Phyto-
plankton Community Parameters ........... ^9
Relationships among temperature, pH , nitrate and
silica ...................... 29
Relationship of nutrients and chlorophyll ..... ^7
3.7 Literature Citied .................. 39
IV Water Masses and Dilution of Surface Waters in the
Straits Area. T. B. Ladewski ............... ^1
4.1 Results ....................... 42
4.2 Literature Cited ................... 53
V Multivariate Statistical Analysis of Physical, Chemical
and Phytoplankton Community Parameters. R. A. Moll .... 56
5.1 Methods ....................... 56
5.2 Results ....................... 57
Factor analyses .................. 57
Cluster analyses .................. 58
5.3 Literature Cited ................... 70
VI Distribution and Abundance of Phytoplankton. E. F.
Stoermer, R. G. Kreis, Jr., and T. B. Ladewski ...... 72
6.1 Materials and Methods ................ 72
6.2 Taxonomic Composition of the Phytoplankton
Assemblage ..................... 76
6.3 Distribution of Major Species ............ 81
6.4 Ordination Analysis of Phytoplankton Assemblages ... 99
Near-surface associations in October ........ 99
Hypolimnetic associations in October ........ 102
Wear-surface associations in September ....... 105
Hypolimnetic associations in September ....... 109
Near-surface associations in August ........ 109
Hypolimnetic associations in August ........ 116
6.5 Comparison of Temperature-Conductivity and Phyto-
plankton Community Patterns ............ 116
Distribution of chemical -physical parameters at
5 m during October ................ 125
6.6 Literature Cited ................... 130
VII Crustacean Zooplankton of the Straits of Mackinac and
Northern Lake Michigan. J. E. Gannon, K. S. Bricker and
T. B. Ladewski ...................... 133
vi
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7.1 Introduction 133
7.2 Methods and Materials 133
Field 133
Laboratory 136
Analytical 136
7.3 Results and Discussion 138
Straits of Mackinac 138
Northern Lake Michigan 172
7.4 Summary 188
7.5 Literature Cited 189
VIII Comparison of Phytoplankton and Nutrients in Northern
Lake Michigan and the Straits of Mackinac 191
8.1 Physical-Chemical Conditions 191
8.2 Phytoplankton 195
8.3 Summary 200
IX Appendices
A. Physical and chemical data collected in the vicinity
of the Straits of Mackinac, 1973 204
A.I Cruise 1, August 1973 204
A.2 Cruise 2, September 1973 209
A.3 Cruise 3, October 1973 216
B. Primary productivity at 5 m. Data in mgCm~3hr~1 . . . 224
B.I Cruise 1, August 1973 224
B.2 Cruise 2, September 1973 225
B.3 Cruise 3, October 1973 227
C. Depth profiles of north-south transects 229
C.I Transect 01-06, Cruise 1, August 1973 229
C.2 Transect 01-06, Cruise 2, September 1973 ... 229
C.3 Transect 01-06, Cruise 3, October 1973 .... 230
C.4 Transect 07-10, Cruise 1, August 1973 231
C.5 Transect 07-10, Cruise 2, September 1973 . . . 231
C.6 Transect 07-10, Cruise 3, October 1973 .... 231
C.7 Transect 13-16, Cruise 1, August 1973 232
C.8 Transect 13-16, Cruise 2, September 1973 . . . 232
C.9 Transect 13-16, Cruise 3, October 1973 .... 233
C.10 Transect 17-23, Cruise 1, August 1973 233
C.ll Transect 17-23, Cruise 2, September 1973 . . . 234
C.12 Transect 17-23, Cruise 3, October 1973 .... 234
C.13 Transect 24-31, Cruise 1, August 1973 235
C.I4 Transect 24-31, Cruise 2, September 1973 ... 236
C.15 Transect 24-31, Cruise 3, October 1973 .... 237
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C.16 Transect 32-37, Cruise 1, August 1973 238
C.17 Transect 32-37, Cruise 3, October 1973 .... 238
C.18 Transect 40-48, Cruise 2, September 1973 . . • 239
C.19 Transect 40-48, Cruise 3, October 1973 .... 240
D. List of species found in phytoplankton collections . . 241
E. Proof that a conservative parameter can be expressed
as a linear combination of other conservative
parameters 250
F. Counts of zooplankton from vertical net tows 252
F.I Cruise 1, August 1973 252
F.2 Cruise 2, September 1973 256
F.3 Cruise 3, October 1973. 260
F.4 Northern Lake Michigan, September 1973 265
vnx
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LIST OF FIGURES
Number Page
1.1 Map of stations in the Straits survey area 3
3.1 Flow chart illustrating sample processing of 4iscrete
depth samples, Straits of Mackinac 1973 15
4.1 Temperature-conductivity plot for October 5-m samples . . 43
4.2 Geographic locations of regions identified in the
temperature-conductivity plot of Figure 4.1 44
4.3 Percent of Lake Michigan water at 5 m for October .... 46
4.4 Percent of Lake Huron water at 5 m for October 47
4.5 Percent of St. Marys River water at 5 m for October ... 48
4.6 Temperature-conductivity plot for September 5-m samples. . 50
4.7 Geographic locations of the regions identified on the
basis of the T-C plot of Figure 4.6 51
4.8 Temperature-conductivity plot for August 5-m samples ... 54
4.9 Geographic locations of the regions identified on the
basis of the T-C plot of Figure 4-8 for September
samples 55
5.1 Surface water distribution in August 60
5.2 Five-meter water distribution in August 61
5.3 Ten-meter water distribution in August 62
5.4 Surface water distribution in September 63
5.5 Five-meter water distribution in September 64
5.6 Ten-meter water distribution in September 65
5.7 Surface water distribution in October 66
5.8 Five-meter water distribution in October 67
5.9 Ten-meter water distribution in October 68
Distribution of:
6.1 total algal cell counts 79
6.2 blue-green algae 80
6.3 green algae 80
6.4 diatoms 82
6.5 Asterionella formosa 83
6.6 Cyclotella comta 83
6.7 Cyclotella. ocellata 84
6.8 Cyclotella operculata 84
6.9 Cyclotella ndchiganiana 86
IX
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Number Page
6.10 Cyclotella stelligera 86
6.11 Fragilaria crotonensis
6.12 Synedra filiformis 87
6.13 Rhizosolenia eriensis
6.14 Tabellaria fenestrata ^
6.15 Tabellaria fenestrata var. intermedia 90
6.16 Chrysococcus dokidophorus
6.17 Chrysosphaerella longispina 91
6.18 Phodomonas minuta var. nannoplanctica 93
6.19 Cryptoncnas ovata 93
6.20 Ankistrodesmus species #3 '
6.21 Crucigenia guadrata 94
6.22 Eutetraworus species #1 95
6.23 Gloeocystis planctonica ..... 95
6.24 Oocystis spp 97
6.25 Anabaena flos-aquae 97
6.26 Anacystis incerta 98
6.27 Anacystis thermalis 98
6.28 Gomphosphaeria lacustris 100
6.29 Oscillatoria bornetii 100
6.30 October 5-m sample ordination plots 101
6.31 Geographic locations of 5-m October phytoplankton
communities 103
6.32 Ordination plots for October surface and subsurface
samples 104
6.33 September 5-m water sample ordination plots 108
6.34 Geographic locations of 5-m September phytoplankton
communities 110
6.35 Ordination plots for September surface and subsurface
samples 112
6.36 August 5-m water sample ordination plots 113
6.37 Geographic locations of 5-m August phytoplankton
communities 115
6.38 Ordination plots for August surface and subsurface
samples 117
6.39 Phytoplankton trends on the T-C plane 123
Cell densities for:
6.40 Cyclotella michiganiana on the T-C plane for October . . 126
6.41 Cyclotella ocellata 127
6.42 Cyclotella stelligera 128
6.43 Trends of physical and chemical parameters in the T-C
plane 129
7.1 Location of zooplankton sampling stations in northern
Lake Michigan, September 1973 135
7.2 Distribution and abundance (numbers of individuals per
m3) of total crustacean zooplankton in the Straits of
Mackinac on three cruises 141
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Number Page
7.3 Distribution and abundance (numbers per m3 and percent
composition) of calanoid copepods in the Straits
region 142
Distribution and abundance of:
7.4 Diaptomus oregonensis in the Straits region 143
7.5 Diaptomus minutus in the Straits region 144
7.6 Diaptomus ashlandi in the Straits region 145
7.7 Diaptomus sicilis in the Straits region 146
7.8 Diaptomus spp. copepodids in the Straits region .... 147
7.9 Limnocalanus macrurus in the Straits region 149
7.10 Senecella calanoides in the Straits region 150
7.11 Epischura lacustris in the Straits region 151
7.12 cyclopoid copepods in the Straits region 152
7.13 Cyclops bicuspidatus thomasi in the Straits region . . . 153
7.14 Cladocera in the Straits region 154
7.15 Daphnia galeata mendotae in the Straits region 155
7.16 Daphnia retrocurva in the Straits region 157
7.17 Daphnia longiremis in the Straits region 158
7.18 Holopedium gibberum in the Straits region 159
7.19 Leptodora kindtii in the Straits region 160
7.20 Eubosmina coregoni in the Straits region 161
7.21 Bosmina longirostris in the Straits region 162
7.22 Diaphanosoma leuchtenbergianum in the Straits region . . 164
Zones of similarity in community structure of
crustacean zooplankton in the Straits region during:
7.23 August 1973 165
7.24 September 1973 as determined by principal component
analysis 166
7.25 October 1973 as determined by principal component
analysis 167
The ratio of calanoid copepods to cladocerans and
cyclopoid copepods in the Straits region during:
7.26 August 1973 173
7.27 September 1973 174
7.28 October 1973 175
7.29 Distribution and abundance (numbers of individuals per
m3) of total crustacean zooplankton in northern Lake
Michigan during September 1973 176
Distribution and abundance of:
7.30 calanoid copepods in northern Lake Michigan 177
7.31 Diaptomus spp. copepodids in northern Lake Michigan . . 178
7.32 Diaptomus oregonensis in northern Lake Michigan .... 179
7.33 Diaptomus sicilis in northern Lake Michigan 180
7.34 cyclopoid copepods in northern Lake Michigan 182
7.35 Cladocera in northern Lake Michigan 183
7.36 Daphnia galeata mendotae in northern Lake Michigan . . . 184
7.37 Daphnia retrocurva in northern Lake Michigan 185
7.38 Eubosmina coregoni in northern Lake Michigan 186
7.39 Holopedium gibberum in northern Lake Michigan 187
XI
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Number
8.1 Location of northern Lake Michigan stations sampled
20-23 September 1973 immediately after the sampling
of the Straits survey area
Distribution of:
8.2 Anacystis incerta ................... 198
8.3 Anacystis thermalis .................. 198
8.4 Fragilaria crotonensis ................. 199
8.5 Cyclotella stelligera ................. 199
8.6 CyclotelJa comta .................... 200
8.7 Cyclotella michiganiana ................ 201
8.8 Asterionella formosa .................. 201
8.9 Cyclotella ocellata .................. 202
8.10 Cyclotella operculata ................. 202
XII
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LIST OF TABLES
Number
1.1 Characteristics of epilimnetic waters, summer 1970 .... 6
1.2 Samples collected on three cruises in 1973 6
1.3 Approximate depths and locations of stations in and near
the Straits of Mackinac 7
3.1 Averages of environmental parameters of epilimnetic waters
on three cruises in the Straits of Mackinac, 1973 ... 18
Correlation of data for:
3.2 all cruises, all depths 30
3.3 all cruises, 5-tn depths with no missing values 30
3.4 August—all stations, all depths 31
3.5 September—all stations, all depths *. 31
3.6 October—all stations, all depths 32
3.7 Stations 01-06, all cruises, all depths 32
3.8 Stations 07-10, all cruises, all depths 33
3.9 Stations 11-12, all cruises, all depths 33
3.10 Stations 13-23, all cruises, all depths 34
3.11 Stations 24-31, all cruises, all depths 34
3.12 Stations 32-37, all cruises, all depths 35
3.13 Stations 38, 39, 49, 50, all cruises, all depths .... 35
3.14 Stations 40-45, all cruises, all depths 36
3.15 Stations 46-48, all cruises, all depths 36
3.16 Correlations of rate of carbon fixation, Secchi disc
transparency, and concentration of silica, nitrate
and total phosphorus with chlorophyll a 38
4.1 Sources of water with ranges of temperature and conduc-
tivity for regions MJ , HI and Sj in Figure 4.2 45
Summary of nitrate, silica, temperature, and conduc-
tivity values for:
4.2 September 52
4.3 August 52
5.1 Factor analysis of Straits data 58
6.1 Example of tabulation of phytoplankton counts 74
6.2 Species and data processing code for phytoplankton used
in the principal component analysis 75
xiii
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Number Page
6.3 Results of the PCA of 5-m phytoplankton samples for the
first three principal components
6.4 Phytoplankton in the Straits of Mackinac 78
6.5 Cell densities at Station 29 above, in and below the
thermocline for August, September and October cruises . 106
6.6 October phytoplankton cell densities
6.7 September phytoplankton cell densities
6.8 August phytoplankton cell densities
6.9 Values of R2 and related statistics from regressions
of cell densities against temperature and conduc-
tivity for the most abundant taxa H9
6.10 Values of R2 from regressions of cell densities
against temperature and conductivity for less abun-
dant taxa H9
6.11 Values of R2 and SD from regressions of physical-
chemical parameters against temperature and conduc-
tivity 130
7.1 List of crustacean zooplankton species collected in
the Straits of Mackinac region during 1973 139
Distribution of zooplankton during:
7.2 August 1973 168
7.3 September 1973 170
7.4 October 1973 171
8.1 Averages of environmental parameters of epilimnetic
waters in Lake Michigan, September 1973 193
Summary of relationships between T-C patterns and
phytoplankton community patterns of:
8.2 August samples 196
8.3 September samples 196
8.4 October samples 197
xiv
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ACKNOWLEDGMENTS
The cooperation and assistance of many persons were essential in complet-
ing this project. The retired U.S. Coast Guard buoy tender MAPLE was
provided, on short notice by the University of Michigan, as a research
vessel to substitute for the R/V INLAND SEAS which had been decommissioned
a few weeks earlier due to the need for extensive repairs. Our Marine
Superintendent Clifford Tetzloff, Captain Richard Thibault and the ship's
crew provided excellent working facilities under these unusual conditions.
Among those who should be acknowledged for their capable assistance in
collecting and processing samples were Kenneth White, Beth Bowman,
Jim Kubus, Denny Berry, Jenny Wagner, Ann Stevens, Kathy Bricker,
Jill Goodell and Dave Rofritz. Larry Horning did the drafting work on
many of the figures. Most of the extensive tabular material was prepared
by Janine Graham. Special credit should be given to Norah Daugherty who
typed the final text and persevered through the complexities of assembling
all the materials in final form.
xv
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SECTION I
INTRODUCTION
The Straits of Mackinac, from the standpoint of physical dynamics, is a
unique area in the Laurentian Great Lakes. It is unique in that the
Straits connect two lakes with the same water level, and although there
is a net water transport from Lake Michigan to Lake Huron the flow os-
cillates between the two lakes. Outflows at other points in the Great
Lakes system are due to differences in water levels.
The oscillatory flow resulting from the connection of two lakes with the
same water level would be expected to produce complicated physical dynam-
ics and possibly a unique biological environment. The physical processes
have been studied infrequently (Powers and Ayers I960; Murty and Rao
1970; FWPCA 1967) . Saylor and Sloss (In press) measured currents and
water movements in the Straits during the time our study was conducted.
The biology and ecology of the Straits of Mackinac, northern Lake
Michigan and northern Lake Huron are poorly known. The benthos has been
studied by Henson (1962, 1970) . To our knowledge there have been no
investigations on the plankton—the limited data available are reviewed
in Sections VI and VII, which present our results on phytoplankton and
zooplankton. Likewise, little is known about the phytoplankton produc-
tivity and major nutrients in the Straits of Mackinac. Indications of
accelerated eutrophication have been reported for Lake Michigan in recent
years (Beeton 1969; Schelske and Stoermer 1971), but the impact of inputs
of Lake Michigan water on eutrophication and primary productivity in the
receiving waters of the Straits of Mackinac and Lake Huron has not been
assessed. A review of the biological and chemical conditions in rela-
tion to the eutrophication and trophic status of Lake Michigan has been
completed recently (Schelske, In press) .
Our study was initiated in late August 1973 with data being collected on
three cruises: 30 August-1 September, 16-18 September and 6-8 October.
The purpose of this investigation was to gather baseline data on environ-
mental quality in the Straits of Mackinac and to use these data as out-
lined in the objectives.
1.1 OBJECTIVES
1) To evaluate the effect of input of water from Lake Michigan on water
1
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quality in the Straits of Mackinac and in the northern part of Lake
Huron.
2) To identify water masses in the Straits of Mackinac, northern Lake
Huron and the St. Marys River, by
a) measuring chemical characteristics,
b) measuring primary productivity of phytoplankton,
c) determining the standing crop, species composition, and
diversity estimates of phytoplankton assemblages,
d) determining the standing crop and species composition of
zooplankton, and
e) measuring concentrations of phosphorus.
3) To evaluate our results in relation to other studies and available
data and to assess whether more detailed studies of input from Lake
Michigan, including estimates of water transport, will be needed to
determine the significance of inputs of water from Lake Michigan on water
quality in Lake Huron.
4) To use our data to assess water quality.
1.2 CURRENT PATTERNS IN THE STRAITS REGION
Although currents in the survey region (Fig. 1.1) are complicated and
highly variable, several generalizations can be made about water move-
ments. Detour Passage, in the northeastern corner of the survey area,
serves as one mouth of the St. Marys River, which empties Lake Superior
into northern Lake Huron. Total net flow at Detour Passage was measured
as 2000 m3/sec (Powers and Ayers 1960). It was shown from drift bottles
and dynamic height calculations that the St. Marys River water is carried
east or west with little tendency to move south in the survey area and
that generally there is counterclockwise surface circulation in the east-
central part of the survey area (Ayers et al. 1956).
Currents at Detour Passage may be considered reasonably constant in
comparison to the highly variable currents at the Straits. The average
net current in the Straits of Mackinac was eastward and ranged from
1500-1900 m3/sec (Powers and Ayers 1960; FWPCA 1967; Saylor and Sloss,
In press) . Extreme variations are due mainly to the 50-60 hr seiche
between Lake Michigan and Lake Huron. The net flow typically changes
from 10,000 m3/sec in one direction to a flow of equal magnitude in the
opposite direction in a period of only 24 hr. During only a small frac-
tion of a month is the instantaneous net flow in the Straits near the
average 1500-1900 m3/sec. Saylor and Sloss (In press) and FWPCA (1967)
found net transport commonly exceeding 20,000 m3/sec in either easterly
or westerly directions. Such a large pulse of water traveling .18 m/sec
for 12 hr moves about 8 km, which may be taken to be an estimate of a
mixing radius near the Straits. Ayers et al. (1956) showed that surface
water, after passing through the Straits from Lake Michigan, generally
-------
u>
46*00'
45"50'
LAKE ,03
MICHIGAN
"^U
BOIS ^-^
BLANC /
ISLAND jl_
*»
/
"28
"27
"25
"24
tORDWOOD
POINT s--
LAKE
HURON
45f301
-84*45'-
-84*30'-
-84*15'
POINT>-
' DETOUR "48
DETOUR^
PASSAGE —
'46
<45—
(44-
84*00-
Figure 1.1. MAP OF STATIONS IN THE STRAITS SURVEY AREA.
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flows southeastward along the southern shore, and that surface current
speeds near Bois Blanc Island were about 4 km/day. From Figure 1.1 it
is clear that stations are, in general, spaced within this mixing radius
and that this mixing radius is fairly large compared with the size of
the survey area.
Despite the extensive mixing, relatively little exchange occurs in the
Straits between the epilimnion and hypolimnion. Powers and Ayers (1960)
on 6 August 1957 found the flow below the thermocline was westerly at
1640 m3/sec while the surface flow was easterly at 3200 m3/sec. Saylor
and Sloss (In press) found 100-day average flows (9 August 1973 to
13 November 1973) of 3320 m3/sec easterly above 20 m and 1400 m3/sec
westerly below 20 m. They also found the greatest difference when the
thermocline was most strongly developed. Before the breakdown of the
thermocline on about 13 September 1973, current velocities above 20 m
(taken to be the location of the therroocline) averaged about 7 cm/sec
easterly but below 20 m were about 7 cm/sec westerly. After 13 Septem-
ber, the average flow of the current was easterly at 3.0 cm/sec above
20 m and 1.5 cm/sec below 20 m. Consequently the average currents above
and below the thermocline are not only independent, they are opposite in
direction during well developed summer stratification. After the break-
down of the thermocline, average currents at all depths would appear to
be easterly in the Straits of Mackinac.
Knowledge of subsurface currents outside the immediate vicinity of the
Straits is limited. Ayers et al. (1956) conducted cruises in the survey
area on 28 June, 27 July and 25 August 1954. On the basis of the dynamic
height technique (Ayers 1956), bottom currents in the deep regions to the
north and east of Bois Blanc Island were westerly. Ayers et al. (1956)
predicted, on the basis of these currents, that upwellings would occur
west of Detour Passage along the northern shore. Upwelling was found in
this area in two out of our three 1973 cruises. It is reasonable to
expect that the westward bottom currents continue along the deep channel
north of Mackinac Island and then south to the Straits of Mackinac, where
they appear as the westward hypolimnetic currents in the Straits. The
absence of upwellings in October 1973 coincided with the absence of
thermal stratification and disappearance of the westward hypolimnetic
flow in the Straits, suggesting that upwelling may be a regular feature
along the northern shore while the Straits are thermally stratified.
Currents of northern Lake Michigan have been studied (e.g. Ayers et al.
1958; FWPCA 1967) but very little information is available for regions
near the Straits because they are, for the most part, relatively shallow.
Consequently it is not possible to determine from previous studies how
far the deep westward currents extend into Lake Michigan.
1.3 DESCRIPTION OF STUDY AREA
The study was restricted to an area that could be sampled from a research
vessel in 3 or 4 days. Factors that entered into consideration were
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logistic, i.e., the distance that could be traversed by the vessel, and
scientific personnel which were not adequate for several days of contin-
uous operation. Based on these considerations the study area extended
90 km from west to east and was 50 km north-south from Station 48 to
Station 40. It was bounded on the west by stations running north-south
between St. Helena Island and Waugoshance Point in Lake Michigan and on
the east by stations between Point Detour and Forty Mile Point in Lake
Huron (Fig. 1.1).
Locations of stations were based on three premises: 1) that there was a
net transport of water from east to west, i.e., that water flows out of
Lake Michigan through the Straits of Mackinac into Lake Huron; 2) that
water from Lake Superior flows through the St. Marys River into Lake
Huron, with part of the water flowing into Lake Huron through Detour
Passage near Station 48; 3) that water characteristics at various points
in the study area would result from mixtures of varying proportions of
waters from Lake Michigan, Lake Superior, and Lake Huron.
Fifty stations were laid out, mostly on north-south transects so water
characteristics could be determined for different parts of the study
area. Stations 01-06, for example, were placed to evaluate and to assess
quality and characteristics of water flowing out of Lake Michigan. In
actuality our results showed evidence of mixing of Lake Michigan and
Lake Huron surface waters on this transect and the presence of a subsur-
face flow from Lake Huron waters to Lake Michigan.
Stations 07-10 were located between Mackinac Island and Rabbit Back Peak
to sample water flowing through the Straits on the north side of Mackinac
Island; Stations 13-23 were located between Bois Blanc Island and the
lower peninsula of Michigan to sample water flowing through the Straits
on the south side of Bois Blanc Island; and Stations 11 and 12 were
located to sample the water flowing through the narrow channel between
Mackinac and Bois Blanc Island. Stations were located between Forty Mile
Point and the Detour Passage to assess water quality in upper Lake Huron
and to measure the influence of water flowing out of Lake Superior through
the St. Marys River.
Chemically the waters in the three lakes are quite distinct, and a number
of parameters are indicative of water masses from the three lakes
(Table 1.1). Lake Huron waters in the study area are largely a mixture
of waters from Lake Michigan and Lake Superior with chemical character-
istics determined by the proportion of water from the two lakes.
Water temperature and specific conductance were useful in identifying
water masses. During the summer, water temperatures in Lake Superior are
somewhat colder than those in the surface waters of Lake Michigan. At
other times of the year, differences in water temperature may not be as
great. Specific conductance on the other hand is always much less in
Lake Superior than in Lake Michigan, with expected values for Lake
Superior being 100 umho @ 25°C and for Lake Michigan about 265 ymho @
25°C (Table 1.1). Values for Lake Huron are intermediate, about 200 umho
@ 25°C in the northern part of the lake.
-------
Table 1.1. CHARACTERISTICS OF EPILIMNETIC WATERS, SUMMER 1970. Averages
from Schelske and Roth (1973, p. 65-67).
Specific
conductance
Lake
N. Michigan
N . Huron
Superior
pH ymho @ 25° C
8.50
8.50
8.04
261
192
95
Sulfate
(mg/1)
15.5
10
1.5
Chloride
(mg/D
7.22
4.6
1.1
. _____ — —
Nitrate
(mg N/l)
0.129
0.139
0.254
"••*
Silica
(mg Si02/D
0.27
1.07
2.28
As pointed out recently (Schelske 1975), silica and nitrate nitrogen can
be used to characterize water masses in the upper Great Lakes. Contrast-
ed with the conservative ions which are more dilute in Lake Superior,
these nutrients are more concentrated in Lake Superior and are diluted
when mixed with waters from Lake Michigan (Table 1.1). Concentrations
of silica in Lake Superior waters, in addition to being relatively large
(> 2.0 mg/1), also vary less seasonally than those in Lake Michigan,
which range from less than 0.1 mg/1 during late summer to more than
1.0 mg/1 during the period when the lake is homothermous (Schelske, In
press). Values for nitrate do not differ as much between the two lakes,
but in the summer, waters from Lake Superior contain at least twice as
much nitrate as those in the outflow from Lake Michigan.
Other chemical parameters, including calcium, sodium, magnesium, potas-
sium and alkalinity, vary greatly among the three lakes. Concentrations
of phosphorus also vary with the smallest concentrations in Lake Superior
and the largest concentrations in Lake Michigan.
More than 800 samples (Table 1.2) were collected at discrete depths as
part of this study; physical-chemical data tabulated in Appendix A were
Table 1.2. SAMPLES COLLECTED ON THREE CRUISES IN 1973. Each sample re-
presents data collected at one depth. C-14 samples include dark samples.
Stations not sampled
C-14 samples at 5 m
Total samples
1
38 - 50
69
217
Cruises
2
13, 20, 21, 32-37
130
272
3
None
156
317
-------
obtained from these samples. Samples for phytoplankton were also taken
at the discrete depths, but samples for zooplankton were obtained with
vertical net hauls. Specific sampling depths for the discrete samples
are listed with the data in Appendix A.
The latitude, longitude and approximate depths for the 50 stations
sampled are listed in Table 1.3.
Table 1.3. APPROXIMATE DEPTHS AND LOCATIONS OF STATIONS IN AND NEAR THE
STRAITS OF MACKINAC.
Station
number
ST-01
ST-02
ST-03
ST-04
ST-05
ST-06
ST-07
ST-08
ST-09
ST-10
ST-11
ST-12
ST-13
ST-14
ST-15
ST-16
ST-17
ST-18
ST-19
ST-20
ST-21
ST-22
ST-2'3
Depth
(meters)
14
20
33
18
14
11
12
31
41
24
24
12
14
24
24
10.5
10
13
22
13
15
18
15
Latitude
45°45.8
45°47.3
45°48.7
45°50.3
45°51.5
45°52.8
45°54.8
45°54.3
45°53.0
45°53.2
45°50.8
45°50.4
45°47.9
45°46.5
45°45.0
45°43.4
45° 41. 2
45°42.1
45°42.9
45°43.8
45°42.6
45°41.8
45°41.0
Location
Longitude
84°51.0
84°51.0
84°51.0
84°51.0
84°51.0
84°51.0
84°42.1
84°41.0
84°40.0
84°38.9
84°35.8
84°37.3
84°35.0
84°35.0
84°35.0
84°35.0
84°30.0
84°30.0
84°30.0
84°30.0
84°25.0
84° 25.0
84°25.0
-------
Table 1.3 continued.
Station
number
ST-24
ST-25
ST-26
ST-27
ST-28
ST-29
ST-30
ST-31
ST-32
ST-33
ST-34
ST-35
ST-36
ST-37
ST-38
ST-39
ST-40
ST-41
ST-42
ST-43
ST-44
ST-45
ST-46
ST-47
ST-48
ST-49
ST-50
Depth
(meters)
16.5
24
33
51
61
69
44
23
19
19
36
45
50
49
19
38
6
46
73
73
110
76
30
22
17
57
39
Latitude
45°40.9
45°43.2
45°45.4
45°47.6
45°49.8
45°52.0
45°54.1
45°56.4
45°57.1
45°55.0
45°53.2
45°51.3
45°50.3
45°49.3
45°38.0
45°35.2
45°30.0
45°32.2
45°35.0
45°40.0
45°45.0
45°50.0
45°54.2
45°56.2
45°56.9
45°54.2
45°54.2
Location
Longitude
84°17.9
84°17.8
84°17.8
84°17.8
84°17.8
84°17.8
84°17.8
84°17.8
84°30.0
84°30.0
84°30.0
84°30.0
84°30.0
84°30.0
84°10.3
84°02.4
83°55.0
83°55.0
83°55.0
83°55.0
83°55.0
83°55.0
83°55.0
83°55.0
83°55.0
84°02.3
84°10.3
1.4 LITERATURE CITED
Ayers, J. C. 1956. A dynamic height method for the determination of
currents in deep lakes. Limnol. Oceanogr. 1: 150-161.
, D. V. Anderson, D. C. Chandler and G. H. Lauff. 1956. Cur-
rents and water masses of Lake Huron. Univ. Michigan, Great Lakes
Res. Div. Pub. 1, 101 p.
-------
, D. C. Chandler, G. H. Lauff, C. F. Powers and E. B. Benson.
1958. Currents and water masses of Lake Michigan. Univ. Michigan,
Great Lakes Res. Div. Pub. 3, 169 p.
Beeton, A. M. 1969. Changes in the environment and biota of the Great
Lakes, p. 150-187. In: Eutrophication, causes, consequences, cor-
rections. Washington: Nat. Acad. Sci.
Federal Water Pollution Control Administration. 1967. Lake currents.
FWPCA, Great Lakes Region, Chicago, 111.
Henson, E. B. 1962. Notes on the distribution of the benthos in the
Straits of Mackinac region. Proc. 5th Conf. Great Lakes Res.,
Univ. Michigan, Great Lakes Res. Div. Pub. 9: 174-175.
. 1970. Pontoporeia affinis (Crustacean, Amphipoda) in the
Straits of Mackinac region. Proc. 13th Conf. Great Lakes Res.:
601-610. Internat. Assoc. Great Lakes Res.
Murty, T. S. and D. B. Rao. 1970. Wind-generated circulations in Lakes
Erie, Huron, Michigan, and Superior. Proc. 13th Conf. Great Lakes
Res.: 927-941. Internat. Assoc. Great Lakes Res.
Powers, C. F. and J. C. Ayers. 1960. Water transport studies in the
Straits of Mackinac region of Lake Huron. Limnol. Oceanogr. 5:
81-85.
Saylor, J. H. and P. W. Sloss. In press. Water volume transport and
oscillatory current flow through the Straits of Mackinac. J. Phys.
Oceanogr.
Schelske, C. L. 1975. Silica and nitrate depletion as related to rate
of eutrophication in Lakes Michigan, Huron, and Superior, p. 277-
298. In: A. D- Hasler (ed.), Coupling of land and water systems,
Springer-Verlag New York, Inc.
. In press. Trophic status and nutrient loading for Lake
Michigan. Report of North American Project of OECD, Study of
Eutrophication. U.S. Environmental Protection Agency.
and J. C. Roth. 1973. Limnological survey of Lakes Michigan,
Superior, Huron and Erie. Univ. Michigan, Great Lakes Res. Div.
Pub. 17, 108 p.
and E. F. Stoermer. 1971. Eutrophication, silica depletion
and predicted changes in algal quality in Lake Michigan.
Science 173: 423-424.
-------
SECTION II
CONCLUSIONS
The Straits of Mackinac and adjacent areas studied in this report comprise
a complex environmental system. The complexity is attributable in part
to three physical factors and their interaction: 1) the oscillatory flow
of water between Lake Michigan and Lake Huron resulting from seiches be-
tween the two lake basins with equal mean elevations; 2) the net transport
of water from Lake Michigan into Lake Huron, since the outflow for Lake
Michigan is through the Straits of Mackinac into Lake Huron; 3) the west-
erly subsurface flow of water from Lake Huron into Lake Michigan, a
phenomenon that is probably restricted to the period of summer -thermal
s tratification.
Oscillatory and subsurface water movements confuse the simple straight-
forward identification of water masses, as they contribute to mixing
over a broad geographical area extending from northern Lake Michigan into
northern Lake Huron. Our study was too limited in the geographic sense
to define the boundaries of the area affected by mixing of water masses.
Water masses characteristic of epilimnetic waters were delineated with
four separate techniques:
1) Multivariate statistical techniques showed that water masses could be
identified with cluster analysis. Stations with similar values for nine
different environmental variables were grouped and identified on maps of
the study area (Sec. V).
2) Ordination analyses of plankton assemblages also were used to group
different stations. In this case the data were counts of zooplankton and
phytoplankton for individual stations. The analyses groups closely
related stations and provided data on the plankton community associated
with each group of stations (Sec. VI, VII).
3) Temperature-conductivity plots were useful in identifying surface
water masses on one of the three cruises. Data from the October cruise
could be used in this analysis since three sources of water, one from
Lake Michigan, one from Lake Huron and one from Lake Superior, were
clearly identifiable on the basis of temperature and conductivity. The
fraction of water from each of the three sources was determined and
plotted (Sec. IV).
10
-------
4) Various analyses for single parameters were used for identification
of water masses. Average values for silica, specific conductance, pH and
to a lesser extent for nitrate nitrogen and water temperature in different
areas were related to water masses. These averages plus isopleths of the
same parameters plotted on depth profiles for the transects sampled could
be used to infer relationships among water masses. Comparison of isopleths
on the depth profiles was the only approach that was applied extensively
to characterization of subsurface water masses (Sec. Ill).
From the standpoint of identifying water masses in this type of survey,
several physical-chemical parameters could have been applied successfully.
Our results showed that specific conductance was very valuable and that
silica, pH, alkalinity and nitrate nitrogen, although not conservative
parameters in the usual sense, had conservative properties in this study
(Sec. Ill, VI).
Although biological communities (phytoplankton and zooplankton) were
readily associated with water masses from the ordination analysis (Sec. VI,
VII), rates of carbon fixation and chlorophyll a varied little among water
masses (Sec. Ill). The apparent cause for this lack of relationship was
that phytoplankton standing crops were so small that differences among
groups of stations could not be detected analytically. These small dif-
ferences in values were also found for rates of carbon fixation and total
phosphorus (Sec. Ill).
Although physicochemical characteristics were only subtly different, the
community structure of crustacean zooplankton reflected water quality
conditions within the Straits region. Species composition was nearly
identical at every station, but principal component analysis based on
percent composition data revealed patterns of community structure remark-
ably similar to water masses identified by cluster analysis (Sec. V). In
general, cladocerans were proportionately most prevalent in waters towards
Lake Michigan and south of Bois Blanc Island while calanoid copepods were
relatively most abundant in waters towards Lake Huron and north of Bois
Blanc Island. Cladocerans have been observed as most characteristic of
eutrophic waters and calanoid copepods most prevalent in oligotrophic
waters elsewhere in the Great Lakes. It is significant that the relative
proportion of these two crustacean zooplankton groups to one another was
a sensitive indicator of water quality in the Straits region where physi-
cochemical conditions differed so subtly (Sec. VII).
The phytoplankton in the Straits of Mackinac region is floristically dis-
similar from the open waters of both Lake Michigan and Lake Huron
(Sec. VI). Besides mixing of populations developed in the primary water
sources, it appears that conditions in the Straits region are favorable
for the development of certain phytoplankton populations not usually
found in offshore plankton assemblages in the upper lakes. Examples of
this are the relatively large populations of Chrysosphaerella longispina
and Chrysococcus dokidophorus noted in our study. The region is also
affected by the injection of normally benthic species into the plankton.
These populations are apparently derived from islands and shoal areas
and from the St. Marys River. In most instances they constitute a
quantitatively minor part of the assemblage.
11
-------
It is clear that populations of blue-green algae developed in Lake
Michigan are being transported to Lake Huron via surface flow through the
Straits of Mackinac. On the basis of our results it appears that the
populations involved are senescent and there is minimal reproduction in
the Straits region and Lake Huron. These populations are characteristic
of moderately eutrophied regions in the Great Lakes, especially regions
with sufficient phosphorus loading to cause silica limitation during the
summer. One of the primary populations involved, Anacystis incerta, is
capable of forming nuisance blooms but does not constitute a nuisance in
quantities noted in the present study. During this study the area most
affected by input from Lake Michigan was the region south of Bois Blanc
Island and the adjacent waters of open Lake Huron (Sec. VIII).
The net transport of water from Lake Michigan to Lake Huron has the fol-
lowing effects on the nutrient enrichment of northern Lake Huron
(Sec. VIII):
1) A relatively rich but diffuse source of phosphorus is supplied. The
degree of enrichment in northern Lake Huron is obviously small, although
the total input is large due to the large flow of water. The flux of
total phosphorus is approximately 10 g P sec"1 (1920 m3 sec"1 x 5.0 mg P
m~3). Estimates could vary greatly due to several uncertainties, includ-
ing errors in measurements of total phosphorus and net transport and
seasonal variations in either or both of these parameters. A change of
0.1 mg P m~3 changes the flux by 4.0%. An error as large as 20% there-
fore might be associated with the estimate of annual phosphorus trans-
port if the error in mean phosphorus concentrations were 0.5 mg P m .
Most of the phosphorus is transported in the particulate form, presumably
combined in biological materials.
2) Silica-depleted waters are supplied, resulting in reduction of silica
concentrations in northern Lake Huron. This relationship is most severe
during late summer and fall, and the reduced supply of silica eventually
will affect diatom standing crops in northern Lake Huron.
3) Nitrate-depleted waters are transported from Lake Michigan, resulting
in decreased concentrations in northern Lake Huron. The effect is great-
est in late summer and early fall when the greatest depletion of nitrate
occurs in Lake Michigan. This relationship is not considered as important
as that for silica and phosphorus since nitrate concentrations are not
diluted to levels that would limit phytoplankton growth. It must also
be recognized that the levels of organic nitrogen are probably greater in
Lake Michigan than in Lake Huron, partly compensating for the nitrate
reduction associated with mixing waters from the two lakes.
During the period of thermal stratification there is a subsurface flow
of water from Lake Huron to Lake Michigan. This water flows west below
the epilimnetic waters of Lake Michigan and is apparently entrained and
mixed with the epilimnetic waters of Lake Michigan in an undetermined
area west of the Straits of Mackinac.
Mixing of waters from Lake Michigan and Lake Huron increases the silica
concentration in the silica-depleted waters of Lake Michigan. Removal or
12
-------
reducing the effect of silica limitation apparently allows some diatom
populations to develop in the Straits area at higher population densities
than occur either in northern Lake Michigan or northern Lake Huron
(Sec. VIII). This relationship also suggests that some other nutrient
limitation, possibly for phosphorus, may be removed by the mixing process.
The transport of relatively high concentrations of phosphorus from Lake
Michigan and the enrichment of mixed waters with silica from Lake Huron
produced relatively large diatom crops in the study area even at times
when Lake Michigan waters were silica depleted and contained significant
populations of blue-green algae. In effect this increased growth of
diatoms and demand for silica extends the potential for silica limitation
from Lake Michigan into Lake Huron. It will also accelerate the rate of
silica depletion in Lake Huron.
Generally it is concluded that there is a subtle effect of water trans-
port from Lake Michigan on the water quality in northern Lake Huron.
Some effects are seasonal; for example, silica-depleted and blue-green
algae-bearing waters are transported from Lake Michigan in the severest
form only during the late summer and fall.
This investigation provides an important and unique data set on the
characterization of the area in and near the Straits of Mackinac. Its
results are the only combined baseline data on plankton and chemistry for
this part of the upper Great Lakes. The study is limited, since the
period of observation was restricted to 40 days, from 30 August to
8 October 1973. Additional data obviously are needed to provide a compre-
hensive analysis of seasonal dynamics.
Future studies should be designed so the effect of short-term changes in
physical dynamics could be included in the study. Part of the influence
of these effects on the data could be minimized by synoptic coverage of
the study area with several ships—the sampling period for each cruise
of our study was about 60 hr or about the same period as that for the
seiche between Lake Michigan and Lake Huron.
Data collection could be refined with a network of buoys that continuously
record data for temperature, specific conductance and currents and with
one or more ships to take additional samples. Data collected at different
stations in the study area could then be related to the physical dynamics.
A larger study area would be needed than we sampled, as there are three
separate questions that could be addressed in future studies:
1) What are the dynamics of transport and mixing between the two lakes?
2) What are the influences of Lake Michigan on northern Lake Huron and
the areal extent of these influences?
3) Is the opposite effect, the influence of Lake Huron on northern Lake
Michigan, restricted primarily to the period of thermal stratification?
13
-------
SECTION III
DESCRIPTION OF PHYSICAL-CHEMICAL CONDITIONS AND
PHYTOPLANKTON COMMUNITY PARAMETERS
by
Claire L. Schelske, Mila S. Simmons, and Laurie E. Feldt
The purpose of this section is to provide background data and to describe
conditions in the Straits of Mackinac on the three cruises in 1973.
3.1 METHODS AND MATERIALS
Prior to each cruise, several types of bottles were prepared for use in
sample collection. Labels containing sample numbers and other identifi-
cation codes were placed on all bottles in which samples would be
collected in the field. One or two days prior to the cruise, 5-dram
glass amber vials were prepared for chlorophyll samples. The vials were
spiked with 8-9 ml of 90% acetone (buffered with 0.1 g/liter of magnesium
carbonate), tightly capped and stored upright in the freezer until needed
for sample introduction on shipboard.
Bottles for alkalinity samples (2-oz polyethylene) were spiked with 5 ml
of 0.01N HC1, tightly capped and stored upright in boxes.
Shipboard Analyses
Water samples were taken with clean 5-liter Nisken bottles, except sur-
face samples which were taken with a clean plastic bucket; sample depths
were generally at 5-m intervals from the surface to 20 m, and at 10-m
intervals below that. As many as 11 depths were sampled at the deepest
stations. Temperature was measured with a bathythermograph and with a
mercury thermometer on shipboard.
Water samples were processed as illustrated in the flow chart (Fig. 3.1).
Samples for chemical analyses were filtered through HA Millipore filter
papers, which were previously rinsed several times and soaked in dis-
tilled deionized water. The bottles for chemical analyses were first
rinsed once with the filtered water before sample introduction.
Specific conductance and pH were measured on board ship immediately after
the water samples were collected. Specific conductance was measured with
14
-------
Filtrate-DISCARD
300
Te
PH
Sp
Al
Raw Water
UNFIL
s
FILTER
*
TERED
1
ml 5(
nperature I
A
=cific conductance
calinity-5 m 0
4
AA Millipore
500 ml; Om, 5m, &
2 other depths
HA Millipore
250 ml
Filter-store in amber vial for gross
Filtrate
rinse 2 oz
bottles first
Filter-store in
phytoplankton
2 oz unfrozen for
chemical analyses
2 oz freeze for
chemical analyses
2 oz freeze for
contingency
amber vial containing
8 ml 90% acetone. Put in freezer
for chlorophyll analyses.
ml 900 ml 60 ml
hytoplankton C-L4 plt in 2 oz
dd 5 drops 5 n bottles &
glutaraldehyde 2 J & ID freeze for
m, 5m & 2 other Us j #1 screen total phosphorus
depths
Figure 3.1.
FLOW CHART ILLUSTRATING SAMPLE PROCESSING OF DISCRETE DEPTH SAMPLES, STRAITS OF MACKINAC
1973.
-------
a Leeds and Northrop Model 4866-60 conductivity bridge equipped with a
temperature compensator. A Corning pH meter Model 111 equipped with a
digital readout and an automatic temperature compensator was used to
measure pH. The two-buffer calibration technique, usually with pH 7.0
and 10.0 buffer solutions, was employed. The sample temperature was
read to 0.1°C with a laboratory mercury thermometer.
The rate of carbon fixation by phytoplankton was measured by a previ-
ously described method (Schelske and Callender 1970). Water samples
(250 ml) were collected in glass-stoppered Pyrex bottles, injected with
2.0 pCi C-14, incubated for 3-4 hr aboard ship and filtered through
47-mm HA Millipore filters. The filters were mounted with rubber cement
on 52-mm diameter aluminum planchets and stored for counting. A Low
Beta Beckmann Planchet Counter was used for counting. Efficiency of
this counter and the absolute activity of the C-14 was determined with a
Nuclear Chicago Liquid Scintillation Counter (Wolfe and Schelske 1967) .
Alkalinity was determined from pH measurements on 20-ml samples to which
5 ml of 0.010N HC1 was added. Alkalinity measurements were performed
only on samples from 5 m where C-14 productivity was measured.
Soluble reactive silica and nitrate nitrogen were measured on board ship
with a TechniconCt) AutoAnalyzer. Silica was determined by the Technicon
AutoAnalyzer Heteropoly-Blue Method. In the method, silica is complexed
with acidified molybdate to form a silicomolybdate complex which is
reduced to an intense heteropolyblue. Oxalic acid was added prior to
the reduction with ascorbic acid to destroy any phosphomolybdate. The
color produced was measured at 630 mp.
Nitrate was reduced by copper-hydrazine solutions to nitrate at 54°C.
The nitrite produced and the nitrite initially present in the sample
were then determined by a diazotization-coupling reaction using
sulfanilamide and N-1-naphthyl-ethylene diamine. This red-violet
colored complex was measured at 520 my (Kamphake et al. 1967). Nitrite
was not analyzed separately, as quantitatively insignificant values
would be expected in non-polluted oxygenated waters.
Samples for chlorophyll (250 ml) were filtered through a 47-mm HA
Millipore filter. The filters were extracted overnight at -10°C with
90% acetone buffered with magnesium carbonate. The samples were then
centrifuged, and 5 ml was transferred to sample cuvettes and read in a
modified Turner Model 111 Fluorometer. The samples were subsequently
acidified and read in the fluorometer for phaeopigment determinations
(Strickland and Parsons 1968). Readings of extracted chlorophyll with
the fluorometer were taken both on board ship and in our laboratories in
Ann Arbor. Samples were maintained in the cold and dark until readings
were taken.
Laboratory Analyses
Frozen samples were transferred from the ship's freezers to large
insulated coolers and brought back to the Ann Arbor laboratory. The
trip was normally 6 hr. Samples remained frozen during transit and were
16
-------
immediately stored in laboratory freezers. The containers used for
transport were large plywood boxes insulated with 5 cm of styrofoam.
Sometimes smaller picnic coolers were used for extra samples, and in
this case blocks of dry ice were used to maintain freezing temperatures
during transport.
Samples were brought back to the laboratory usually at the end of each
cruise, which was normally after a week. Analyses were usually completed
within a week to a month's time depending upon the availability of per-
sonnel to do the analyses.
Chemical analyses for ammonia, total phosphorus, total soluble phosphorus,
chloride and sulfate were performed on thawed samples with the Technicon
AutoAnalyzer in the laboratory. Most of the methods employed were
Technicon AutoAnalyzer methods or modified ones. All analyses except the
one for total phosphorus were performed on samples of filtered water.
Ammonia was oxidized to nitrous acid by hypochlorite which reacts with
phenol to give a blue color. The reaction was catalyzed by nitroprusside
and buffered by EDTA. The color produced was measured at 630 mp (H. E.
Allen, U.S. Bureau Sport Fish, and Wildlife, Ann Arbor, Mich., unpublish-
ed manuscript). A special sampling chamber wherein acid-scrubbed air
was constantly purged was used to minimize ammonia contamination from
the atmosphere.
Samples for total phosphorus and total soluble phosphorus were concen-
trated by evaporation and digested with potassium persulfate for 1.5 hr
in an oven at 110°C. The samples were then treated with an acidic solu-
tion of ammonium molybdate to give phosphomolybdate which was then
reduced by ascorbic acid to give a blue color and measured at 630 my.
Chloride reacts with mercuric thiocyanate to form mercuric chloride. The
released thiocyanate reacts with ferric ammonium sulfate to form a red
complex, Fe(SCN)3- The resulting color was measured at 480 mp.
An automated turbidimetric method was used for the determination of
sulfate. The turbidity produced by the reaction of BaCl2 in HC1 with
sulfate was measured at 420 mp. An NH^-OH-EDTA rinse was used to pre-
vent the coating of the BASOt^ precipitate on the walls of the manifold
system and the flow cells (Santiago et al. 1975).
3.2 EPILIMNETIC AVERAGES AND SEASONAL VARIATION
Data from the averages for eight parameters indicate the range of condi-
tions observed in surface waters during the three cruises (Table 3.1).
Averages for different groups of stations represent conditions for
different parts of the study area: Stations 01-06 for Lake Michigan,
Stations 40-45 for Lake Huron and Stations 46-48 for the St. Marys River.
17
-------
oo
Table 3.1. AVERAGES OF ENVIRONMENTAL PARAMETERS OF EPILIMNETIC WATERS ON THREE CRUISES IN
THE STRAITS OF 1IACKINAC, 1973. Data arc mean + one Dtandard deviation.
Stations
Cruise 1
Cruise 2
Cruise 3
Stations
Temperature (C)
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
21.1 ± .0.44
19.5 ± 1.44
21.3 ± 0.77
21.6 ± 0.70
20.9 ± 0.55
20.3 ± 0.83
N.S.
N.S.
15.4 ± 0.87
11.4 ± 1.10
14.4 ± 0.46
13.1 ± 1.07
10.1 ± 1.48
N.S.
13.3 ± 2.13
12.7 ± 1.35
Specific conductance (10~'*mho
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
2.496 ± 0.056
2.397 ± 0.062
2.445 ± 0.040
2.101 ± 0.102
2.208 ± 0.086
2.272 ± 0.064
N.S.
N.S.
2.354 ± 0.127
2.270 ± 0.059
2.348 ± 0.115
2.280 ± 0.100
2.025 ± 0.182
N.S.
2.064 ± 0.136
1.500 ± 0.194
14.4 ± 0.49
12.2 ± 0.29
13.4 ± 0.51
12.4 ± 0.28
12.4 ± 0.68
12.2 ± 0.28
11.2 ± 0.80
13.6 t 0.78
cm-')
2.462 ± 0.062
2.018 ± 0.063
2.300 ± 0.138
1.940 ± 0.085
1.768 ± 0.075
1.934 ± 0.131
2.045 ± 0.098
1.498 ± 0.226
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
Cruise 1
Cruise 2
Cruise 3
Chlorophyll a (mg m 3)
1.51 ± 0.14
1.25 ± 0.17
1.22 ± 0.16
1.12 ± 0.11
1.16 ± 0.23
1.22 ± 0.17
N.S.
N.S.
Silica
0.510 ± 0.090
0.696 ± 0.104
0.586 + 0.117
0.689 ± 0.082
0.679 ± 0.117
0.635 ± 0.120
N.S.
N.S.
1.73 ± 0.70
1.21 ± 0.36
1.67 ± 0.10
1.78 ± 0.12
1.26 ± 0.29
N.S.
1.71 ± 0.17
1.38 i 0.24
(mg Si02 I'1)
0.951 ± 0.162
1.235 ± 0.082
1.007 ± 0.053
1.047 ± 0.032
1.299 ± 0.172
N.S.
0.946 ± 0.160
1.754 ± 0.140
1.60 ± 0.24
1.45 ± 0.16
1.33 ± 0.28
1.56 ± 0.39
1.71 ± 0.36
1.56 ± 0.29
1.43 ± 0.40
1.26 ± 0.24
1.292 ± 0.129
1.416 ± 0.081
1.162 ± 0.213
1.144 ± 0.071
1.318 ± 0.133
1.504 ± 0.128
1.150 ± 0.111
1.674 ± 0.269
-------
Table 3.1 continued.
Stations
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
Cruise 1
8.658 ± 0.050
8.635 ± 0.050
8.657 ± 0.021
8.662 ± 0.017
8.627 ± 0.025
8.653 ± 0.016
N.S.
N.S.
Secchi
5.02 ± 0.32
6.03 ± 0.15
5.62 ± 0.43
8.08 ± 0.43
8.00 ± 0.66
6.70 ± 0.47
N.S.
N.S.
Cruise 2
pH
8.514 ± 0.063
8.372 ± 0.098
8.498 ± 0.048
8.512 ± 0.048
8.315 ± 0.099
N.S.
8.441 ± 0.093
8.123 ± 0.038
transparency (m)
3.86 ± 0.79
4.88 ± 0..48
4.63 ± 0.25
5.67 ± 0.76
6.67 ± 1.76
N.S.
6.73 ± 1.47
3.83 ± 1.44
Cruise 3
8.416 + 0.065
8.226 ± 0.063
8.401 ± 0.060
8.284 ± 0.058
8.236 ± 0.047
8.240 ± 0.065
8.335 ± 0.055
8.140 ± 0.060
Stations
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
Cruise 1
Nitrate
143 ± 16
159 ± 16
187 ± 37
222 ± 33
198 ± 15
180 ± 12
N.S.
N.S.
Cruise 2
(ugN I'1)
212 ± 69
276 ± 19
241 ± 51
241 ± 41
341 ± 33
N.S.
246 ± 41
293 ± 19
Cruise 3
177 ± 19
308 ± 9
246 ± 18
310 ± 16
322 ± 11
299 ± 31
285 ± 16
323 ± 5
Total phosphorus (pgP I"1)
6.82 ± 0.76
7.20 ± 0.85
6.55 ± 0.72
7.32 ± 0.54
7.10 ± 0.84
8.33 ± 0.93
9.42 ± 2.08
4.77 ± 1.97
1-6
7-10
13-23
24-27
28-31
32-37
40-45
46-48
4.63 ± 0.93
3.35 ± 1.20
3.16 ± 0.98
1.45 ± 0.47
3.02 ± 1.0.6
2.88 ± 0.73
N.S.
N.S.
4.76 ± 0.90
3.26 ± 2.12
3.96 ± 1.27
3.32 ± 0.83
4.08 ± 1.20
N.S.
3.21 ± 1.66
4.20 ± 0.72
5.10 ± 0.53
5.17 ± 1.78
4.02 ± 1.80
4.49 ± 1.14
3.93 ± 1.02
4.50 + 1.67
3.66 ± 1.12
3.66 ± 1.42
-------
Water Temperature
Surface water temperatures, as would be expected, generally decreased
during the three cruises. On the August cruise, surface temperatures
were generally greater than 20°C, but the easternmost transect, where
lower temperatures from water flowing out of the St. Marys River might
have been observed, was not sampled. Most of the surface water cooling
occurred between Cruises 1 and 2; a much smaller amount of cooling and
in fact an increase in temperatures occurred at some stations between
Cruises 2 and 3 (Table 3.1).
Temperature relationships among the groups of stations on the three
cruises were strongly influenced by two factors on the September cruise.
As pointed out below, the depth of the mixed layer increased between
Cruises 1 and 2, and upwelled water in September tended to decrease
average surface temperatures. The presence of upwelled water was evident
from average temperatures for Stations 28-31 and 07-10. At these two
groups of stations epilimnetic temperatures were lowest on Cruise 2.
By Cruise 3, average temperatures for Stations 46-48 were greater than
the adjacent waters, reflecting the large amount of thermal inertia in
Lake Superior or indicating a relatively constant temperature in the out-
flow from Lake Superior between the two cruises (App. C-18, C-19).
Specific Conductance
From a conservative parameter such as specific conductance, inferences
can be made about relationships and origins of water masses. It was
obvious, for example, that on all three cruises water sampled at Stations
01-06 in Lake Michigan was diluted with Lake Huron water, as the specific
conductance (Table 3.1) was lower than the expected range of 260-270 ymho
cm"1 (Table 1.1) in northern Lake Michigan. The influence of water flow-
ing out of Detour Passage from Lake Superior via the St. Marys River was
evident also in the average specific conductance for Stations 46-48.
Although averages were much lower for Stations 46-48 than for other sta-
tions, they were considerably greater than the average of 95 umho cm"1
for Lake Superior or the minimum value of about 120 measured on Cruise 3.
Averages larger than Lake Superior values were due to dilution with
Lake Huron water, with an average specific conductance of 205 ymho cm""1
at Stations 40-45 for Cruises 2 and 3 (Table 3.1).
It was evident from these data that on each cruise water found at Stations
01-06 had a specific conductance most closely related to water found at
Stations 13-23. Values at these two groups of stations also were the
largest of any sampled, indicating the largest proportion of Lake Michigan
water in the study area.
Dilution and mixing of surface water masses originating from Lake
Superior, Lake Huron and Lake Michigan are evident from the data on
average specific conductance and are considered in greater detail in
Section 4.0.
20
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Hydrogen Ion Concentration
Obvious features of the pH data were largest values in Lake Michigan with
smallest values in the area near Detour Passage and a general decrease in
values seasonally (Table 3.1). Larger values were found in Lake Michigan
due to a greater buffering capacity than present in either Lake Huron or
Lake Superior; in addition, waters of Lake Michigan are buffered above
the equilibrium pH of about 8.4 (Schelske and Callender 1970), leading
to the precipitation of marl or "milky water" (Ladewski and Stoermer
1973). Photosynthetic activity and increasing water temperature during
the summer cause the pH to be greater than the equilibrium values. The
decrease in pH during the sampling period was due to mixing surface
waters with colder subsurface waters of lower pH and to the decrease in
water temperature which increases the solubility of carbon dioxide and
reduces pH (Schelske and Callender 1970).
Secchi Transparency
There was no seasonal trend in Secchi disc transparency; lowest readings
were found on the second cruise.
Transparency was least in two areas, one in Lake Michigan waters repre-
sented by Stations 01-06 and 13-23 and the other in St. Marys River
water represented by Stations 46-48 (Table 3.1). The smaller transpar-
encies in these areas were not entirely a reflection of relatively large
standing crops of phytoplankton, as the lowest chlorophyll concentrations
were found at Stations 46-48. Inorganic turbidity must have contributed
to reduced transparency at Stations 46-48 and also, possibly, at Stations
01-06 and 13-23. Ladewski and Stoermer (1973) found that minimum Secchi
disc transparency in September was caused by milky water. Greatest
transparencies were found in the areas most remote from Lake Michigan
and Detour Passage and were at Stations 24-31 on Cruise 1, Stations 28-
31 and 40-45 on Cruise 2, and Stations 40-45 on Cruise 3.
Chlorophyll a
Concentrations of chlorophyll a varied little among the data for the
survey. Averages for groups of stations ranged only from 1.1-1.8 during
the study (Table 3.1). For most stations, the largest average was found
on Cruise 2 when the water transparency was lowest. With the small dif-
ference between the averages, additional discussion of chlorophyll
averages is not warranted other than to point out that many of the stand-
ard deviations were less than 10% of the mean values. Variance in
chlorophyll data is frequently much larger.
Soluble Reactive Silica
Silica changed seasonally, with concentrations increasing from the first
to the last cruise. Water at Stations 01-06 and 13-23, with the great-
21
-------
est proportion of Lake Michigan water, contained the smallest concentra
tions of silica; largest concentrations were at Stations 46-48 due to
the input of St. Marys River water (Table 3.1).
Concentrations of silica in Lake Michigan water (Stations 01-06) on
Cruise 1 averaged greater than 0.5 mg/liter, a value greater than expected
for Lake Michigan water in August or September. In late August, concen-
trations of silica in surface waters of Lake Michigan would be less than
0.2 mg/liter and possibly less than 0.1 mg/liter. Concentrations of
silica on Cruises 2 and 3 also were greater than expected for Lake
Michigan surface waters. Silica concentrations higher than expected
resulted from the mixing of water relatively enriched with silica from
Lake Huron with water from Lake Michigan in the Straits area. The
source of water for the increased concentrations was not Lake Michigan,
as surface water concentrations remain below 1.4 mg/liter until December
or January (Rousar 1973). The source of silica-rich water was the
westerly subsurface flow from Lake Huron.
Nitrate Nitrogen
On each cruise, the smallest average nitrate nitrogen concentration was
found at Stations 01-06 in Lake Michigan; the largest concentrations were
found at Stations 46-48 near Detour Passage and at Stations 28-31
(Table 3.1). These relationships are due to the input of water with
relatively low nitrate concentration from Lake Michigan and water with
relatively high nitrate concentration from Lake Superior (Table 1.1).
At Stations 28-31 the large average in September was due to upwelled
water (App. C-14) with high nitrate concentrations. The data also show
that Lake Huron waters contained relatively large concentrations of
nitrate in comparison to Lake Michigan waters.
Nitrates generally increased during the three cruises, but the trend was
not as definite as found for silica. The large average for nitrate on
Cruise 2 at Stations 01-06 was probably due to a smaller proportion of
Lake Michigan water than on Cruises 1 and 3; on Cruise 2, the average
specific conductance was the lowest of the three cruises, indicating
greater intrusion of waters from Lake Huron, Lake Superior, or both
sources (Table 3.1).
Total Phosphorus
There were no obvious seasonal trends in total phosphorus and, with the
exception of Stations 24-27, there was very little difference in the
average concentrations. With the exception of the one value of 1.5 yg P/
liter, averages ranged from 2.9 to 5.2 pg P/liter. For the three cruises,
the largest averages were for Stations 01-06, ranging from 4.6 to 5.1 yg
P/liter (Table 3.1). There is some indication that the lowest values
for each group of stations occurred on Cruise 1; however, if there were
smaller concentrations during the first cruise, the differences appeared
22
-------
to be too small to be detected statistically due to the relatively large
variances.
Because phosphorus limits algal growth in the upper Great Lakes, small
concentrations should be associated with small standing crops of phyto-
plankton. The smallest average for total phosphorus, 1.5 pg P/liter was
found for Stations 24-27 on Cruise 1. At these stations, chlorophyll
concentrations were also minimal and Secchi disc transparency was rela-
tively large, indicating that phytoplankton standing crops were smaller
than at surrounding stations (Table 3.1). Generally, however, there
were no obvious relationships between averages for total phosphorus and
algal standing crops. One probably should not expect to see definite
relationships between means of total phosphorus and chlorophyll since
the range of these variables was small during the study. For the com-
plete data set the expected relationship was obtained, i.e. that small
standing crops of chlorophyll would be associated with small concentra-
tions of phosphorus.
3.3 PHYSICAL-CHEMICAL CONDITIONS IN AUGUST
The description here and in 3.4 and 3.5 for the September and October
cruises is based on data presented in Appendix A and Appendix C. Raw
data are tabulated in Appendix A, while isopleths of water temperature,
pH, specific conductance and silica are plotted in Appendix C for depth
profiles of each transect sampled. Specific references will not be made
to these appendices each time data are presented, but will be added when
data in appendices may be of particular interest to the reader.
Water Temperature
On the August cruise, surface water temperatures were fairly uniform
over the study area (Table 3.1). Temperature on the Lake Michigan trarii-
sect (Stations 01-06) varied from 21.0° to 21.8°C. South of Bois Blanc
Island temperatures ranged from 21.0° to 22.0°C. On the transect to the
east of Bois Blanc Island (Stations 24-31), surface temperatures ranged
from 20°C at the northern end of the transect to 22°C at the southern
end. At Station 07 near Rabbit's Back Peak, water was relatively cold;
the temperature was 17°C at the surface and the isotherms indicate that
upwelling may have occurred in this vicinity (App. C.4). Water in the
harbor at St. Ignace at this time was very cold, as attested by members
of the ship's scientific crew who attempted to swim after the day's work
was completed on 31 August.
Thermal stratification was pronounced on all transects sampled except the
three south of Bois Blanc Island, and even on these transects stratifi-
cation was present although not as strong as found at other sampling
sites. The minimum isotherm south of Bois Blanc Island was 12°C, which
was one degree warmer than the minimum isotherm for the Lake Michigan
23
-------
transect (Stations 01-06). At these stations the epilimnion extended to
a depth of about 15 m. North and east of Bois Blanc Island the thermo-
cline was much shallower with the epilimnion extending only to about 10 m.
At Stations 31 and 32, the distribution of isotherms near the surface
indicates intrusion of relatively cold water along the north shore
(App. C.13 and C.16). The origin of this cold water may be related to
the upwelling noted for Station 07.
Specific Conductance
Epilimnetic waters on the Lake Michigan transect (Stations 01-06) had
values for specific conductance >250 ymhos. South of Bois Blanc Island
specific conductance in the epilimnion was >240 ymhos. On these same
transects, subsurface values for specific conductance were lower,
decreasing to 220 ymhos near the bottom (App. C.I, C.7, C.10). These
low values indicate intrusion of Lake Huron water below the thermocline
(Lake Michigan water would have a specific conductance of at least
260 ymhos).
On the transect north of Bois Blanc Island (Stations 32-37) (App. C.16)
and on the transect east of Bois Blanc Island (Stations 24-31), values
for specific conductance were comparable to the minimum values found
south of the island or about 220 ymhos (App. C.13). On both of these
transects, however, there is a minimum for specific conductance at 15-20 m
that is most obvious between Stations 26-30 and Stations 34-37. These
relatively low values are indicative of a separate water mass.
Hydrogen Ion Concentration
Values of pH in the epilimnetic water at Stations 01-06 and for the three
transects (Stations 13-23) on the south side of Bois Blanc Island were
greater than 8.6 (Table 3.1). Maximum values were 8.70 at Stations 01,
05 and 06. At the other stations sampled on this cruise, surface values
were also above 8.6 except Stations 07 and 31 where the values were 8.58
and 8.57 respectively.
In the relatively deep waters on transects 32-37 and 24-31, values for
pH were less than 7.8. On the Lake Michigan transect, Stations 01-06,
the minimum isopleth was 8.2 at 25 m—pH values of 8.2 were also found at
20 m on the next transect to the east, Stations 13-16.
Silica
Surface values for silica were generally lowest on the Lake Michigan
transect, Stations 01-06, and on the three transects south of Bois Blanc
Island, Stations 13-23, with the range of values being about 0.1 mg/liter
or from less than 0.5 to less than 0.6 mg/liter. The lowest value
observed at all the stations was 0.36 mg/liter at Station 32, representing
a pocket of low silica water that probably originated in Search Bay or
24
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some other nearshore area (App. C.16).
Highest values for silica in surface waters, values greater than 0.7 mg/
liter, were found at Stations 07, 33, and 31 along the north shore of the
Straits and at Stations 25 and 26 east of Bois Blanc Island. These high
values undoubtedly represent the presence of water masses with a greater
percent composition of Lake Huron or Lake Superior water than the other
stations.
Vertical stratification of silica was very pronounced at all stations,
although to a lesser degree at the stations with the highest silica
values. Values for bottom samples ranged from 1.4 mg/liter at 25 m on
the Lake Michigan transect (App. C.I) to 1.8 mg/liter on the transects
with deeper water, i.e., the transect north of Mackinac Island (App. C.4)
and the two transects north and east of Bois Blanc Island (App. C.13,
C.16). On the transect north of Mackinac Island, 1.8 mg/liter was found
at depths >30 m while on the other transects this much silica was not
present at all stations and if present was restricted to water below 30 m.
3.4 PHYSICAL-CHEMICAL CONDITIONS IN SEPTEMBER
On the September cruise the distribution of environmental parameters was
more varied than on the preceding cruise due to the effects of weather
and the fact that an additional transect, Stations 40-48, was sampled.
Strong winds from the south made it impossible to sample Stations 13, 20,
and 21 located on the windward shore, and had a profound effect on the
water masses—including producing upwelling between Stations 29 and 30.
Water Temperature
Surface water temperatures varied from a maximum of 16°C in Cecil Bay at
Station 01 to less than 9°C at Station 30 in an upwelling area. Temper-
atures west of the Straits (Stations 01-06) and south of Bois Blanc
Island (Stations 13-23) were warmer than in other areas, and greater than
14°C at all stations. North of Mackinac Island and on transects east of
Bois Blanc Island, surface temperatures were less than 13°C except along
the south shore where they exceeded 16°C at some stations.
Thermal stratification was weak or nonexistent at stations west of the
Straits and those south of Bois Blanc Island. Epilimnetic depths on
these transects were 15-20 m—there was evidence of stratification at
Station 19 due to the presence of 10°C at a depth of 20 m.
Two temperature distributions on this cruise were not observed on the
previous cruise. One was the presence of upwelled water in the vicinity
of Station 29; the other was the presence of relatively warm water flow-
ing out of Detour Passage, that was sampled at Stations 46-48. These
25
-------
two water masses are easily identifiable also by chemical parameters,
particularly specific conductance and silica (App. C.13, C.18).
Specific Conductance
Patterns of specific conductance were not related to distribution of
temperature on the Lake Michigan transect, Stations 01-06, and on tran-
sects south of Bois Blanc Island, Stations 13-23. Water with high
specific conductance was found along the south shore at Stations 01
(App. C.2) and 23 (App. C.ll) where water temperatures were greatest.
Highest specific conductance water was found at Stations 22 and 23,
indicating a greater proportion of Lake Michigan water than found at
other stations; relatively high specific conductance water was present
as far east and south as Stations 40, 41 and 42 (App. C.18), indicating
flow of Lake Michigan water to this area. One or two lenses of low
specific conductance water were also found near the surface on transect
1-6. These results indicate a considerable amount of mixing in an area
extending from Lake Michigan south of Bois Blanc Island to Stations
40-42 in Lake Huron.
Water flowing out of Detour Passage was identifiable by low specific
conductance, less than 130 pmhos at Station 48, and by relatively warm
temperature (App. C.18).
On transect 24-31, upwelled water had specific conductance values of less
than 2.1 in the vicinity of Station 30. There was also a lens of low
specific conductance water near Government Island at Station 31—this
lens was associated with relatively low water temperature but was not
correlated with either silica or pH (App. C.14).
Hydrogen Ion Concentration
Largest values for pH were found on transect 1-6, at transects 13-23
south of Bois Blanc Island and at the south end of the two transects east
of Bois Blanc Island. These values ranged from >8.4 to >8.6, values
which would be typical of Lake Michigan water. Highest values were
found at Station 01 at the surface and between 10 and 15 m at Stations
18 and 19. Since Station 20 was not sampled, it is difficult to ascer-
tain the distribution of water masses on transect 17-20.
Minimum values for pH ranged from 8.0-8.1 and were found in deep waters
on the two transects east of Bois Blanc Island, north of Mackinac Island
and in the water flowing out of Detour Passage.
Silica
High silica concentrations were found at Station 04 in Lake Michigan.
Since these high values were associated with values for specific conduct-
ance of 220 ymho they presumably can be attributed to the intrusion of
26
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Lake Huron water (App. C.2). South of Bois Blanc Island, the isopleths
for silica appear to run in the vertical plane rather than horizontal;
interesting is the fact that on two transects the largest values are on
the south shore and on the other transect they are on the north shore
(App. C.8, C.ll). The presence of isopleths in this area that extend
from the surface to the bottom, separating the water into horizontal
components, is suggested also by the data for water temperature, specific
conductance and pH. The relationships suggest mixing of Lake Huron and
Lake Michigan waters. It is very obvious on transect 24-31 (App. C.14)
that discrete water masses are present in the horizontal plane—partly
due to the surface water mass along the south shore and partly to the
upwelled water in the vicinity of Station 30.
Epilimnetic water with a silica concentration of 1.8 mg/liter can be
attributed to the influence of water flowing out of Detour Passage. As
would be expected, high silica water is present in the deeper waters of
the two transects east of Bois Blanc Island (App. C.14, C.18). These
values range from 1.8 to 2.2 mg/liter—concentrations characteristic of
Lake Superior water; however, due to the conductivities greater than
200 ymho associated with this water, the origin of high silica is not
attributable directly to the presence of Lake Superior water. The
specific conductance indicates that a considerable portion of this water
originated in Lake Huron.
3.5 PHYSICAL-CHEMICAL CONDITIONS IN OCTOBER
Water Temperature
In October there was no thermal stratification on the Lake Michigan tran-
sect nor on those south of Bois Blanc Island (App- C.3, C.9, C.12).
Temperature on these transects ranged from 12° to 14°C. On transects
north and west of Bois Blanc Island, the epilimnion was 25-30 m deep,
(App. C.15, C.19) but on the transect northwest from Mackinac Island
(App. C.6) there was no thermal stratification to a depth of 35 or 40 m.
Warmest temperatures were found on the transect in Lake Michigan and in
the water flowing out of Detour Passage (Stations 46-48).
Specific Conductance
On the Lake Michigan transect, the relatively homothermous waters were
reflected by small variations in specific conductance with values ranging
from <240 ymho to <250 ymhos (App. C.3). On two transects south of Bois
Blanc Island (App. C.12) there was an intrusion of lower conductivity
water along the south shore of Bois Blanc Island with values ranging from
200-220 ymhos. This low conductivity water, based on conductivities on
transect 24-31, apparently represented an intrusion of Lake Huron water
(App. C.15). Relatively high conductivity water extended along the south
shore of the study area from Station 01 to Station 40.
27
-------
Water from Detour Passage was easily identified by low specific conduct-
ance values, ranging as low as 120 pmho at Station 48 (App. C.19).
Hydrogen Ion Concentration
Values for pH were relatively uniform on the Lake Michigan transect and
on those south of Bois Blanc Island. Like specific conductance, larger
values were present along the south shore of the study area, but unlike
specific conductance, there was less variation from east to west with
the range of values being approximately 0.2 pH units or from >8.3 to
>8.5. East and north of Bois Blanc Island, surface pH values ranged from
8.10 to <8.3 with water from the Detour Passage having a pH of about 8.1.
Subsurface values for pH ranged as low as 7.8 at Station 37 north of
Bois Blanc Island, but in general most values were not lower than 8.0.
Silica
On the Lake Michigan transect, Stations 01-06, there was evidence of
vertical as well as horizontal distributions of silica (App. C.3). Ver-
tical stratification was present at the three stations on the south end
of the transect, but to the north of Station 03 the gradients were
horizontal, increasing northward from 1.2 to >1.4 rag/liter. The same
range of values was present at Stations 01-03, but with values increasing
with depth from the surface to the bottom.
South of Bois Blanc Island the distribution of silica was relatively
complex, with different patterns of distribution on each of the three
transects sampled. Smallest values were found on transect 13-16, values
that were less than or equal to those found on the Lake Michigan tran-
sect (App. C.9). On the next transect to the east, 17-20, the values
were all equal to or greater than the largest values for transect 13-16.
In addition, on transect 17-20 the smallest values were found in the
middle of the transect, which was due partly to two large values for
silica found at Station 17 (App. C.12). One of the values at Station 17
exceeded 2.0 mg/liter (surface), but this value appeared real since the
5-m value was 1.7 mg/liter. The pattern of low values at mid-transect
was repeated on transect 21-23, and on both transects 17-20 and 21-23
isopleths indicated horizontal gradients of silica. Horizontal gradients
of silica concentration were also found on the transect north of Mackinac
Island (App. C.6), along the north end on transect 32-37 (App. C.17) and
possibly on the north end on transect 24-31 (App. C.15). These relation-
ships indicate a homogeneous mass of water along the north shore which
may be a mixture of water from Detour Passage (App. C.19) and Lake Huron.
If this is the case, as suggested by the distribution of specific conduct-
ance, then it may have been produced by westerly currents along the north
shore.
Water flowing out of Detour Passage had a silica concentration of 2.2 rag/
liter, comparable to what would be expected from a source in Lake Superior
28
-------
(Table 1.1). Below 30 m on the three transects with deep water north
and east of Bois Blanc Island, vertical stratification of silica was also
present.
On this cruise, surface values for silica were generally higher along the
north shore of the study area and lowest on the south shore. The one
obvious exception is Station 17 along the south shore, which had one of
the highest values for silica, the origin of which is not known.
3.6 CORRELATION OF PHYSICAL, CHEMICAL AND PHYTOPLANKTON COMMUNITY
PARAMETERS
As a preliminary step to data analysis, 14 correlation matrices were
run, one for each of the following tables:
Table 3.2 All cruises, all depths, with missing data
3.3 All cruises, 5-m depths, without missing data
3.4 August, all stations, all depths
3.5 September, all stations, all depths
3.6 October, all stations, all depths
All cruises, all depths:
3.7 Stations 01-06
3.8 07-10
3.9 11-12
3.10 13-23
3.11 24-31
3.12 32-37
3.13 38, 39, 49, 50
3.14 40-45
3.15 46-48
The data were therefore analyzed as a total group, as groups for each
cruise, and as groups similar to those listed in Table 3.1.
Although significant correlations do not connote causal or functional
relationships between two factors, they do indicate associated variables
and how one parameter varies in relation to another parameter. Several
associations were found by examining the correlation matrices.
Relationships Among Temperature, pH, Nitrate and Silica
Highly significant correlation coefficients were found for the six
possible correlation coefficients for temperature, pH, nitrate and silica
(Table 3.2). These results show that high silica and nitrate concentra-
tions and low pH values are associated with cold water with the converse
being true for warm water, or that temperature was correlated negatively
with silica and nitrate and positively with pH. Highly significant
29
-------
Table 3.2. CORRELATION OF DATA FOR ALL CRUISES, ALL DEPTHS. N = 768,
R @ .99 = .10.
Secchi
Temp
pH
C14-ls
Chi
Si02
N03
P Tot
Table 3.3.
Secchi
1.00
-0.33
-0.32
-0.36
-0.24
0.23
0.33
-0.09
Temp
1.00
0.86
0.11
0.41
-0.79
-0.78
0.14
CORRELATION
MISSING
pH C14-ls Chi
1.00
0.16 1.00
0.48 0.24 1.00
-0.84 -0.16 -0.36
-0.78 -0.38 -0.36
0.10 0.16 0.23
OF DATA FOR ALL CRUISES,
VALUES. N = 98, R <§ .99
Si02 NO 3 P Tot
1.00
0.75 1.00
-0.04 -0.11 1.00
5-M DEPTHS WITH NO
= .26.
Secchi
Temp
pH
Cl4-ls
Chi
Si02
NO 3
P Tot
Secchi
1.00
-0.22
-0.17
-0.37
-0.06
-0.02
0.21
-0.16
Temp
1.00
0.78
0.13
-0.25
-0.68
-0.68
-0.02
pH Cl4-ls Chi
1.00
0.16 1.00
-0.21 0.26 1.00
-0.80 -0.15 0.29
-0.73 -0.42 0.08
-0.13 0.20 0.11
Si02 N03 P Tot
1.00
0.62 1.00
0.20 -0.10 1.00
30
-------
Table 3.4. CORRELATION OF DATA FOR AUGUST—ALL STATIONS, ALL DEPTHS.
N = 199, R @ .99 = .19.
Secchi
Temp
pH
C14-ls
Chi
Si02
N03
P Tot
Table 3.5.
Secchi
1.00
-0.42
-0.42
-0.34
-0.35
0.47
0.49
-0.61
Temp
1.00
0.95
0.19
0.34
-0.95
-0-87
0.28
CORRELATION
N =
pH Cl4-ls Oil Si02 NO 3
1.00
0.08 1.00
0.44 0.04 1.00
-0.96 -0.20 -0.40 1.00
-0.86 -0.25 -0.34 0.87 1.00
0.28 -0.03 0.31 -0.29 -0.25
OF DATA FOR SEPTEMBER—ALL STATIONS, ALL
259, R @ .99 = .16.
P Tot
1.00
DEPTHS
Se cchi
Temp
pH
C14-ls
Chi
Si02
N03
P Tot
Secchi
1.00
-0.58
-0.39
-0-43
-0.32
0.23
0.40
-0.09
Temp
1.00
0.82
0.31
0.66
-0.70
-0.73
0.21
pH C14-ls Chi Si02 N03
1.00
0.21 1.00
0.65 0.19 1.00
-0.76 -0.40 -0.61 1.00
-0.62 -0.40 -0.50 0.74 1.00
0-07 0.12 0-15 -0.11 -0.16
P Tot
1.00
31
-------
Table 3.6. CORRELATION OF DATA FOR OCTOBER—ALL STATIONS, ALL DEPTHS.
N = 313, R @ .99 = .15.
Secchi
Temp
pK
C14-ls
Chi
Si02
NO 3
P Tot
Table 3.7.
Secchi
1.00
-0.49
-0.16
-0.12
-0.17
0.01
0.23
-0.01
Temp
1.00
0.72
0.39
0.68
-0.34
-0.62
0.26
CORRELATION OF
DEPTHS .
PH C14-ls Chi Si02 N03 P Tot
1.00
0.14 1.00
0.59 0.38 1.00
-0.60 0.05 -0.33 1.00
-0.75 -0.54 -0.40 0.39 1.00
0.17 0.36 0.27 0.01 -0.16 1.00
DATA FOR STATIONS 01-06, ALL CRUISES, ALL
N = 77, R @ .99 = .30.
Secchi
Temp
PH
C14-ls
Chi
Si02
NO 3
P Tot
Secchi
1.00
-0.23
-0.36
-0.15
-0.33
0.50
-0.15
0.15
Temp
1.00
0.87
-0.12
-0.05
-0.89
-0.55
-0.03
pH C14-ls Gil Si02 N03 P Tot
1.00
-0.65 1.00
-0.10 0.76 1.00
-0.90 0.31 0.55 1.00
-0.50 -0.23 -0.02 0.44 1.00
-0.08 0.38 0.29 0.14 -0.05 1.00
32
-------
Table 3.8. CORRELATION OF DATA FOR STATIONS 07-10, ALL CRUISES» ALL
DEPTHS. N - 66, R @ .99 = .32.
Secchi
Temp
pfi
C14-ls
Chi
Si02
NO 3
P Tot
Table .
Secchi
1.00
0.38
-0.04
-0.36
0-49
-0.07
0.02
0.59
Temp
1.00
0.85
-0.14
0.41
-0.91
-0.90
0.12
3.9. CORRELATION
DEPTHS
pH C14-ls Chi Si02 N03
1.00
0.02 1.00
0.29 -0.18 1.00
-0.95 -0.14 -0.27 1.00
-0.95 -0.08 -0.23 0.97 1.00
-0-08 -0.37 0.25 -0.05 0.09
OF DATA FOR STATIONS 11-12, ALL CRUISES,
. N = 27, R @ .99 = .49.
P Tot
1.00
ALL
Secchi
Teiap
PH
C14-ls
Chi
Si02
NO 2
P Tot
Secchi
1.00
0.03
-0-41
-0.55
-0.18
0.38
0.15
-0.12
Temp
1.00
0.86
0.09
-0.29
-0.84
-0.95
-0.18
pK Cl4-ls Chi SiO:. N03
1.00
0.46 1.00
-0.06 0.17 1.00
-0.93 -0.41 0.22 1.00
-0.91 -0.29 0.12 0.87 1.00
-0.12 -0.20 0.09 0.20 0.84
P Tot
1.00
33
-------
Table-3.10, CORRELATION OF DATA FOR STATIONS 13-23, ALL CRUISES, ALL
DEPTHS. N = 110, R @ .99 = .25.
Secchi
Temp
pH
CU-ls
Chi
Si02
NO 5
P lot
Table 3
Secchi
1.00
-0.17
-0.35
-0.73
-0.43
0.23
0.10
0.10
Temp
1.00
0.90
0.15
-0.37
-0.82
-0.54
0.03
.11. CORRELATION
DEPTHS
pH C14-ls Chi Si02
1.00
0.32 1.00
-0.23 0.32 1.00
-0.73 -0.21 0.23 1.00
-0.59 -0.31 0.11 0.39
-0.05 -0.02 -0.12 0.01
OF DATA FOR STATIONS 24-31, ALL
. N = 207, R @ .99 = .18.
N03 P Tot
1.00
0.13 1.00
CRUISES, ALL
Secchi
Temp
pH
Cl4-ls
Chi
Si02
N03
P Tot
Secchi
1.00
0.10
-0.10
-0.50
-0.17
-0.02
-0.03
-0.17
Temp
1.00
0.85
0.26
0.36
-0.88
-0.84
-0.15
pH C14-ls Chi Si02
1.00
0.60 1.00
0.46 0.13 1.00
-0.87 -0.47 -0.39 1.00
-0.74 -0.53 -0.31 0.85
-0.05 -0.38 0.20 0.13
NO 3 P Tot
1.00
0.20 1.00
34
-------
Table 3.12. CORRELATION OF DATA FOR STATIONS 32-37, ALL CRUISES, ALL
DEPTHS. N = 90, R @ .99 = .27.
Secchi
Temp
pE
C14-ls
Chi
Si02
NO 3
P Tot
Table 3
Secchi Temp
1.00
-0.19 1.00
-0.34 0.90
0.38 -0.79
0.07 0.41
0 . 39 -0 . 86
0.40 -0.88
0.57 -0.05
. 13 . CORRELATION
CRUISES, ALL
pH C14-ls Chi S102
1.00
-0.77 1.00
0.50 0.66 1.00
-0.92 0.82 -0.33 1.00
-0.84 0.68 -0.25 0.82
-0.12 0.14 0.24 0.22
OF DATA FOR STATIONS 38, 39, 49,
DEPTHS. N = 57, R @ .99 = .34.
N03 P Tot
1.00
0.32 1.00
50, ALL
Se cchi
Temp
pH
C14-ls
Chi
Si02
N03
P Tot
Secchi Temp
1.00
-0.39 1.00
-0.46 0.66
-0.67 0.78
-0.15 0.74
0-28 -0.68
0.25 -0.44
-0.02 -0.16
pH C14-1S Chi Si02
1.00
0.63 1.00
0.53 0.23 1.00
-0.69 -0.38 -0.58 1.00
-0.57 -0.49 -0.53 0.75
-0.003 0.20 0.05 -0.03
NO 3 P Tot
1.00
-0.29 1.00
35
-------
Table 3.14. CORRELATION OF DATA FOR STATIONS 40-45, ALL CRUISES, ALL
DEPTHS. N = 104, R @ .99 = .25.
Secchi
Temp
pK
Cl4-ls
Chi
Si02
NO;
P Tot
Table 3
Secchi
1.00
-0.20
-0.14
0.08
-0.09
0.13
0.28
0.09
Temp
1.00
0.83
-0.24
0.69
-0.62
-0.67
0.27
.15. CORRELATION
DEPTHS
pH C14-ls Chi Si02
1.00
-0.20 1.00
0.83 0.12 1.00
-0.58 -0.70 -0.59 1.00
-0.60 -0.62 -0.51 0.84
0.15 0.14 0.18 -0.21
OF DATA FOR STATIONS 46-48, ALL
. N = 32, R @ .99 = .45.
N03 P Tot
1.00
-0.28 1.00
CRUISES, ALL
Secchi
Temp
PH
CIA-Is
Chi
Si02
NO 3
P Tot
Secchi
1.00
-0.30
0.53
-0.37
-0.25
-0.66
0.43
-0.28
Temp
1.00
0.32
-0.58
0.35
0.43
-0.18
0.14
pH C14-1& Chi Si02
1.00
-0.04 1.00
0.13 0.71 1.00
-0.26 0.28 0.48 1.00
0.07 -0.26 -0.32 -0.42
-0.26 0.29 0.55 0.39
NO 3 P Tot
1.00
-0.16 1.00
36
-------
correlation coefficients were found because the water column was strati-
fied thermally and chemically for most of the stations. To a lesser
extent, these relationships were found because water from Lake Huron and
the outflow from the St. Marys River were usually colder than the surface
waters of Lake Michigan (Table 3.3). Surface water from Lake Michigan
had higher pH and lower silica and nitrate than the other waters.
That nitrate, silica, and pH were correlated with temperature can be seen
from the correlation matrices for the three cruises. On Cruise 1, when
water temperature differences were greatest among the stations, the six
correlation coefficients for the variables ranged from .86 to .96
(Table 3-4) and on Cruise 2 from .62 to .82 (Table 3.5). By Cruise 3,
when thermal stratification was limited to a few stations, correlation
coefficients of silica with temperature and nitrate were -.34 and .39
and the other correlation coefficients ranged from .60 to .75 (Table 3.6).
Only eight other correlation coefficients for silica, nitrate, temperature
and pH were less than 0.5. Two of these were between nitrate and silica
for Stations 13-23 (Table 3.10) and between nitrate and temperature for
Stations 38, 39, 49, 50 (Table 3.13). The remaining six were all the
coefficients for Stations 46-48 (Table 3.15).
Correlations for nitrate, silica, pH and temperature at Stations 46-48
obviously differed from the other stations. Not only were all the cor-
relation coefficients less than -42 (Table 3.15), but some had opposite
signs in comparison to the other groups. The correlation coefficient
for silica and nitrate was -.42 whereas all other coefficients for this
pair of variables were positive (Tables 3.2-3.14). Silica likewise was
positively correlated with temperature, but the relationship was negative
at other stations. The positive correlation of silica and temperature
is related to water originating in the St. Marys River with higher silica
and temperature than the adjacent waters in Lake Huron. In other areas
of the lake, warm surface waters were silica-depleted in relation to the
colder and deeper waters.
Relationship of Nutrients and Chlorophyll
In nutrient-limited systems, the standing crop of phytoplankton might be
expected to be correlated with nutrients and other phytoplankton community
parameters. These relationships can be tested partly from correlation
coefficients between the standing crop of phytoplankton, measured as
chlorophyll a, and other parameters such as concentration of silica,
nitrate and total phosphorus, rate of carbon-14 uptake, and Secchi disc
transparency. Although chlorophyll was not consistently correlated with
any of these parameters, most of the correlations among these variables
were highly significant (Table 3.16).
Correlation coefficients for silica and chlorophyll were highly signifi-
cant, excepting those for Stations 07-10, 11-12, and 13-23 (Table 3.16).
Some of the highly significant correlations, however, were positive while
others were negative. Highly significant positive correlation coefficients
37
-------
Table 3.16. CORRELATIONS OF RATE OF CARBON FIXATION, SECCHI DISC TRANS-
PARENCY, AND CONCENTRATION OF SILICA, NITRATE AND TOTAL PHOSPHORUS
WITH CHLOROPHYLL A. Data from Tables 3.2-3.15.
a
r
.30
.32
.49
.25
.18
.27
.34
.25
.45
.26
.10
.19
.16
.15
Station
01-06
07-10
11-12
13-23
24-31
32-37
38, 39, 49, 50
40-45
46-48
allb
all
A
S
0
N
77
66
27
110
207
90
57
104
32
98
768
199
259
313
C-14
.76
-.18
.17
.32
.13
.66
,23
.12
.71
.26
.24
.04
.19
.38
Secchi
-.33
.49
-.18
-.43
-.17
.07
-.15
-.09
-.25
-.06
-.24
-.35
-.32
-.17
Si02
,55
-.27
.22
.23
-.39
-.33
-.58
-.59
.48
.29
-.36
-.40
-.61
-.33
NO 3
-.02
-.23
.12
.11
-.31
-.25
-.53
-.51
-.32
.08
-.36
-.34
-.50
-.40
TPOit
.29
.25
.09
-.12
.20
.24
.05
.18
.55
.11
.23
.31
.15
.27
Approximate critical value for r at the .01 probability level.
Only at 5-meter depths where there were no missing data.
were obtained at Stations 01-06 with the most silica-depleted water
(Table 3.7) and with the complete set of data that included only near-
surface samples for which all data were available (Table 3.3). Both sets
of data indicate silica was limiting, since standing crops increased with
larger concentrations of silica. At Stations 46-48, the positive correla-
tion coefficient seems to have resulted from relatively large concentra-
tions of silica in the St. Marys River water (Table 3.15). Correlation
coefficients for chlorophyl of .71 with carbon fixation and .55 with
total phosphorus indicate that water from the St. Marys River was phos-
phorus-limited, as the phytoplankton community parameters increased with
phosphorus concentration.
Highly significant correlation coefficients for nitrate and chlorophyll
were all negative, indicating that in at least these groups of stations
nitrate was not limiting or that increased standing crops of chlorophyll
reflected nutrient decreases or nutrient utilization by phytoplankton
(Table 3.16).
38
-------
Few highly significant correlations were obtained between chlorophyll and
total phosphorus (Table 3.16). It is important to note, however, that
for the complete data set and for the data by cruises there were highly
significant correlations. The correlation coefficients were small, prob-
ably reflecting the large variances in these two groups of data.
Most of the correlations between rates of carbon fixation and chlorophyll
were positive, as expected, but only about half of the coefficients were
highly significant (Table 3.16). Since rates of carbon fixation were
measured at only 5 m, the only meaningful correlation may be the one for
the 5-m samples. For this group of samples the correlation coefficient
and the critical value for r were equal. Only three sets of coefficients
indicated that measurements of chlorophyll a and rates of carbon-14 were
as highly related as measurements of temperature, nitrate, silica and
pH. These were the coefficients for Stations 01-06, 32-37 and 46-48,
but the causes for only finding a small number of these highly related
measures are not obvious.
Most of the correlations between Secchi disc transparency and chlorophyll
were negative, as expected, but only half of the coefficients were highly
significant (Table 3.16) . One of the highly significant values, .49 for
Stations 07-10, was positive, which we cannot explain. Like chlorophyll,
the complete data set and the samples by cruises had highly significant
correlations. In addition, highly significant correlations were found
for Stations 01-06 and 13-23. It was obvious that transparency measure-
ments could not have been used to estimate standing crops of chlorophyll.
Correlations by themselves are not particularly illuminating. In
Section V, multivariate techniques are used to analyze the data set.
3.7 LITERATURE CITED
Kamphake, L. J., S. A. Hannah, and J. M. Cohen. 1967. Automated analysis
for nitrate by hydrazine reduction. Water Res. 1: 205-216.
Ladewski, T. B. and E. F. Stoermer. 1973. Water transparency in south-
ern Lake Michigan in 1971 and 1972. Proc. 16th Conf. Great Lakes
Res.: 791-807. Internat. Assoc. Great Lakes Research.
Rousar, D. C. 1973. Seasonal and spatial changes in primary production
and nutrients in Lake Michigan. Water, Air, and Soil Pollution 2:
497-514.
Santiago, M. A., Saundra Fielek and C- L. Schelske. 1975. Automated
method for sulfate determination in lake water. Water Quality
Parameters, ASTM STP 573, Amer. Soc. for Testing and Materials,
p. 35-46.
39
-------
Schelske, C. L. and E. Callender. 1970. Survey of phytoplankton produc-
tivity and nutrients in Lake Michigan and Lake Superior. Proc. 13th
Conf. Great Lakes Res.: 95-105. Internat. Assoc. Great Lakes
Research.
, L. E. Feldt, M. A. Santiago and E. F. Stoermer. 1972.
Nutrient enrichment and its effect on phytoplankton production and
species composition in Lake Superior. Proc. 15th Conf. Great Lakes
Res.: 149-165. Internat. Assoc. Great Lakes Research.
Strickland, J. D. H. and T. R. Parsons. 1968. A practical handbook of
seawater analysis. Bull. Fish. Res. Bd. Canada No. 167. 311 p-
Wolfe, D. A. and C. L. Schelske. 1967. Liquid scintillation and geiger
counting efficiencies for carbon-14 incorporated by marine phyto-
plankton in productivity measurements. J. Cons. Perm. int. Explor.
Her. 31: 31-37.
40
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SECTION IV
WATER MASSES AND DILUTION OF SURFACE WATERS IN THE STRAITS AREA
by
Theodore B. Ladewski
Epilimnetic water may be considered to be bounded on the top by the air-
water interface and on the bottom by the thermocline. The degree to
which the epilimnetic water is affected by inputs across the top and
bottom boundaries is difficult to quantify, but will be a function of the
transit time of water through the Straits area, which was estimated to
be 19 days. Inputs across the upper surface will be assumed to be unim-
portant over this transit time and will be ignored. Except in the case
of obvious upwelling, inputs from the hypolimnion will also be ignored,
leaving three major inputs to the Straits survey area: Lake Michigan,
the St. Marys River, and Lake Huron. The flow from the St. Marys River
at Detour Passage was estimated to be 2000 m3 sec"1 (Powers and Ayers
1960) . The average net flow at the Straits between 9 August and 13
November 1973 above 20 m was 3320 m3 sec"1 (Saylor and Sloss, In press) .
The next largest source of water is the Cheboygan River with an average
flow of 21 m* sec"1 between August and October 1973 (USGS 1973, 1974).
Since this source is dwarfed by comparison with the flow from Lake
Michigan and the St. Marys River, it and other rivers in the area likely
have only minor effects on the surface waters.
The purpose of this section is to describe and provide background infor-
mation on relationships among surface-water masses related to the three
major inputs during the period of our study.
To trace the water movements from Lake Michigan and the St. Marys River
into the Straits area, conservative parameters were needed. "Conserva-
tive concentrations" are defined by Sverdrup et al. (1942) as those
"that are altered locally, except at the boundaries, by the processes of
diffusion and advection only." An alternate definition for "conserva-
tive," used in this paper, is: A quantity is conservative if its
measured value X in a mixture of volumes V.^ of water from N different
sources is equal to:
N
X = i=l ViXi (1)
N
I V
41
-------
where Xj_ = measured value of the parameter at source 1^ This relation-
ship may be rewritten as:
N
I FXi where
N
A conservative parameter therefore is one which dilutes proportionately
with its quantity in the water. Examples of parameters not conserved
according to this definition are pH, Secchi depth or any which are sub-
ject to biological or chemical reactions or to phase change.
Temperature and conductivity were chosen as conservative parameters to
be used to trace water masses because these measurements are simple and
subject to little experimental error. Conductivity is a function of
concentrations of all ions including bicarbonate. However, its correla-
tion with chloride at 5 m is quite high (r = .96) so it may be considered
to be relatively unaffected by the biota. Water temperature could not
be considered conservative if local cooling or warming rates are compara-
ble to rates of temperature change due to surface-water mixing. The size
of the survey region is sufficiently small on a meteorological scale so
it is reasonable to expect air temperatures and other meteorological
conditions to be relatively uniform over the area at any one time. Cli-
matic cooling will reduce the resolution of the technique of using water
temperature to distinguish water masses but is not likely to be a factor
during a 3-day cruise.
4.1 RESULTS
To identify water masses, temperature was plotted vs. conductivity.
Clusters of stations with similar temperature and conductivity were
circled and labeled on Figure 4.1 and the geographical locations indi-
cated on Figure 4.2. The difference in the locations between 24 and 24R
or 30 and 30R, two stations which were sampled on different days, indi-
cated the extent of daily variation and measurement error of temperature
and conductivity. It is evident that there are three extreme regions:
MI located west of the Straits in Lake Michigan at Stations 01-03, Hj
located east of the Straits in Lake Huron at Stations 41 and 42, and Sj
located at Station 48 at the mouth of the St. Marys River.
Sources of water with temperature and conductivity for each of the re-
gions in Figure 4.2 are shown in Table 4.1. It is evident that the
regions cannot be distinguished from temperature alone since water from
the St. Marys River and Lake Michigan have similar temperatures. Resolu-
tion of water masses, however, is possible for specific conductance
(Table 4.1).
Stations 01, 42, and 48 may be considered as the primary sources of
water due to their location on the triangle in Figure 4.1. The plot of
42
-------
260
LAKE MICHIGAN
M,
12 13
TEMPERATURE *C
Figure 4.1. TEMPERATURE-CONDUCTIVITY PLOT FOR OCTOBER 5-M SAMPLES.
Numbers refer to the stations at which the samples were taken.
The temperature and conductivity of a station (at 5 m) is indi-
cated by the position of its number. Note that all stations are
included by a triangle connecting Stations 01, 42, and 48. See
Figure 4.2 for the geographic locations of the labeled regions.
43
-------
-84°30'
Figure 4.2. GEOGRAPHIC LOCATIONS OF REGIONS IDENTIFIED IN THE TEMPERATURE-CONDUCTIVITY
PLOT OF FIGURE 4.1.
-------
Table 4.1. SOURCES OF WATER WITH RANGES OF TEMPERATURE AND CONDUCTIVITY
FOR REGIONS Mls El AND Si IN FIGURE 4.2,
Region Source Temperature Conductivity
MI
HI
Si
Lake
Lake
Lake
Michigan
Huron
Superior
High
Low
High
(14.8-15
(10.5-11
(13.8-14
.0)
.0)
.3)
High
Interned .
Low
(248-252)
(214-218)
(118-146)
the regions (Fig. 4.2) also suggests that water is diluted from the three
sources into the central stations of the survey area.
Assuming three sources of water represented by Stations 01, 42 and 48,
it is possible to estimate the fraction of each of the three water types
at the surface location X, if F£ (X) is defined as the fraction of water
at X originating from source i_, where:
i=l represents the source at Station 01,
i=2 represents the source at Station 42,
i=3 represents the source at Station 48.
Since there are three sources assumed:
I F±(X) = Fj(X) + F2(X) + F3(X) = 1 (2)
for any surface point X inside the survey area. Since temperature and
conductivity are assumed to be conserved (see Eq. 1):
Z F±(X) I± - T(X) and (3)
I F±(X) C± = C(X) <4>
i-1
where: T- is the temperature at source l^Cj. the conductivity at
source 1/T (X) the temperature at point X, and C (X) the conductivity
at point X. Equations 2, 3 and 4 were solved simultaneously for the F±
at each station.
Several general conclusions may be drawn from the distribution of calcu-
lated fractions of water from Lake Michigan, Lake Huron and the St. Marys
River (Figs. 4.3-4.5) during the October cruise. First the contours are
generally smooth, indicating that the assumptxons behind Eqs. 2-4 and
the hypothesis that water types can be traced using temperature and con-
45
-------
Figure 4.3. PERCENT OF LAKE MICHIGAN WATER AT 5 M FOR OCTOBER. Lake Michigan water ±s assumed
to be represented by Station 01. Numbers written at each station give the percentage of Lake
Michigan water as calculated using temperature and conductivity.
-------
84-ocr-
Figure 4.4. PERCENT OF LAKE HURON WATER AT 5 M FOR OCTOBER.
-------
.p-
00
-84-45'
Figure 4.5. PERCENT OF ST. MARYS RIVER WATER AT 5 M FOR OCTOBER.
-------
ductivity are valid. One apparent inconsistency for Station 17 may be
due to effects from the Cheboygan River which would be expected to have
a high temperature and conductivity, thus making it appear, on the basis
of these parameters, as a station characteristic of Lake Michigan.
Second, little water from Lake Michigan was present in the northeastern
corner of the sample area. Water from Lake Michigan flowed along the
southern shore and was evident at Station 40, on the southeastern corner
of the survey area, where approximately 43% of the water was from the
source in Lake Michigan. This flow of water into Lake Huron from Lake
Michigan closely parallels the results of Ayers et al. (1956), who showed
water of high temperature and conductivity and high concentrations of
magnesium and calcium flowing eastward through the Straits and along the
southern shore in all three of their synoptic cruises.
Third, water comprised of a mixture from the St. Marys River and Lake
Huron flowed westward along the northern shore from Detour Passage.
Since Detour Passage is situated on the eastern edge of the survey area,
it is not clear whether there is an additional flow eastward. Either an
eastward or westward current may occur at Detour Passage, although the
westward current appears more predominant (Ayers et al. 1956). In addi-
tion, the water from the area of Station 42, initially identified as
coming from Lake Huron, appears to be moving north and west. This appar-
ent northward current at Station 42 is consistent with observation of
similar northward currents measured by drogues in the summer of 1966
(Sloss and Saylor, In press) . Apparently, mixing of Lake Huron and
St. Marys River water occurred in the northeastern half of the survey
area with very little inclusion of Lake Michigan water (Fig. 4.3).
Six regions were identified from the plot of temperature vs. conductivity
(Fig. 4.6) for September samples, as indicated on the map of the study
area (Fig. 4.7). At this time one distinct water mass, S, was identified
as originating from the St. Marys River. The remaining five regions are
distributed along a gradient from MI, with the highest temperature and
conductivity, to U with the coldest temperature and an intermediate
conductivity. In contrast with the previous cruise, Lake Michigan water
with a specific conductance of 265 ymho was not present at Stations 01-06;
the highest specific conductance, 250 pmho, was found at Station 23-
These conductivity relationships indicate that considerable mixing of
Lake Michigan and Lake Huron waters occurred in the MI and M2 regions.
Region U is cold with a high nitrate concentration characteristic of
hypolimnetic water (Table 4.2), suggesting that upwelling occurred at
region U prior to the time of sampling. The conductivity is lower in
region U than in the hypolimnion, indicating that hypolimnetic water
mixed with westward flowing water from the St. Marys River.
Regions US and UM appear to be derived from a mixture of waters from U
and S and U amd M. The location of these regions (Fig. 4.7) and their
intermediate temperature suggests they orginated from an upwelling along
49
-------
260
240
220
§
200
E
180
o
z>
o
o
o |60
140-
120
UM.
10 II 12 13
TEMPERATURE °C
14
IS
16
17
Figure 4.6. TEMPERATURE-CONDUCTIVITY PLOT FOR SEPTEMBER 5-M
SAMPLES. Numbers refer to stations at which the samples
were taken. See Figure 4.7 for the geographic locations of
the labeled regions.
50
-------
Figure 4.7. GEOGRAPHIC LOCATIONS OF THE REGIONS IDENTIFIED ON THE BASIS OF THE T-C PLOT OF
FIGURE 4.6.
-------
Table 4.2. SUMMARY OF NITRATE, SILICA, TEMPERATURE, AND CONDUCTIVITY VALUES FOR SEPTEMBER.
Ul
N)
Parameter
N03
Si02
Temp.
Cond.
Table
Overall range
for 5-m
samples
133 - 362
.73 - 1.89
8.5 - 16.8
126 - 253
4.3. SUMMARY OF
Range for
samples below
40 m
296 - 393
1.32 - 2.23
4.2 - 6.1
220 - 222
Range in
region U
(5 m)
274 - 362
Range in Range in
region S region MI
(5 m) (5 m)
258 - 295 133 - 252
1.26 - 1.50 1.85 - 1.89 .73 - .87
8.5 - 10.0 13.2 - 13.8 15.8 - 16.
163 - 219
NITRATE, SILICA, TEMPERATURE, AND
126 - 142 223 - 247
CONDUCTIVITY VALUES FOR
Units
MgN/1
mgSi02/l
8 °C
ymho/cm
AUGUST .
Parameter
N03
Si02
Temp.
Cond.
Overall range
for 5-m
samples
126 - 244
.43 - .96
17.0 - 22.0
196 - 225
Range for
samples below
40 m
306 - 364
1.45 - 1.96
4.5 - 7.5
215 - 222
Range in
region U
(5 m)
188 - 244
.43 - .91
17.0 - 18.
200 - 227
Value at
region H
(station 25, 5m)
214
.70
1 20.9
197
Units
ygN/1
mgSi02/l
°C
ymho/cm
-------
the northern shore some time prior to the survey or to an intrusion of
relatively cool Lake Huron water.
Unfortunately stations representative of the sources were not sampled,
as indicated by Figure 4.6, so it is not possible to compute the fraction
of water from each source as was done for the October samples (Figs. 4.3-
4.5). Instead of three sources, there appear to be at least four sources
for surface water in the survey area: surface waters of Lake Michigan,
Lake Huron, and the St. Marys River, plus the hypolimnion of Lake Huron.
An additional conservative parameter would be needed to compute fractions
from each source. Nevertheless, the stations do form a rough triangle,
suggesting that the most important sources are Lake Michigan, St. Marys
River and the hypolimnion of Lake Huron.
Five regions were identified on the plot of temperatures vs. conductivity
for the August samples, one region including only Station 25 (Fig. 4.8),
and the relationship among the water masses is much more difficult to
interpret than the previous cruise. A water mass characteristic of Lake
Michigan extends through the Straits and south of Bois Blanc Island
(Fig. 4.9). Upwelled water is present along the north shore, but the
limited sampling area makes it difficult to determine its extent and
origin. According to chemical data, the upwelled water mass, U, and the
water mass at Station 25 appear to be Lake Huron water (Table 4.3) be-
cause N03-N, Si02 and conductivity are more characteristic of Lake Huron
than of the other lakes.
4.2 LITERATURE CITED
Ayers, J. C., D. V. Anderson, D. C. Chandler and G. H. Lauff. 1956.
Currents and water masses of Lake Huron. Univ. Michigan, Great
Lakes Res. Div. Pub. 1. 101 p.
Powers, C. F. and J. C. Ayers. 1960. Water transport studies in the
Straits of Mackinac region of Lake Huron. Limnol. Oceanogr. 5:
81-85.
Saylor, J. H. and P. W. Sloss. In press. Water volume transport and
oscillatory current flow through the Straits of Mackinac. J. Phys.
Oceanogr.
Sloss, P. W. and J. H. Saylor. In press. Lake scale current measurements
in Lake Huron. J. Geophys. Res.
Sverdrup, H. U., M. W. Johnson and R. H. Fleming. 1942. The oceans:
their physics, chemistry, and general biology. Englewood Cliffs:
Prentice Hall, Inc. 1087 p.
U.S. Geological Survey. 1973; 1974. Water resources data for Michigan.
Surface water records. USGS, Okemos, Mich.
53
-------
260
240
16 20 21
TEMPERATURE *C
22
Figure 4.8. TEMPERATURE-CONDUCTIVITY PLOT FOR AUGUST 5-M
SAMPLES. Numbers refer to stations at which the
samples were taken. See Figure 4.9 for geographic
locations.
54
-------
Ui
Ul
Figure 4.9. GEOGRAPHIC LOCATIONS OF THE REGIONS IDENTIFIED ON THE BASIS OF THE T-C PLOT OF
FIGURE 4.8 FOR SEPTEMBER SAMPLES.
-------
SECTION V
MULTIVARIATE STATISTICAL ANALYSIS OF PHYSICAL, CHEMICAL AND
PHYTOPLANKTON COMMUNITY PARAMETERS
by
Russell A. Moll
The Straits of Mackinac is one of the most interesting areas of the
Laurentian Great Lakes in terms of physics, chemistry, and biology
(Henson 1962, 1970; Powers and Ayers 1960). The narrow juncture between
Lake Michigan and Lake Huron is known for its unusual current conditions,
as water is exchanged between the two lakes (Powers and Ayers 1960; Murty
and Rao 1970; FWPCA 1967; Mortimer 1975). Knowledge of the distribution
and movement of water masses in relation to biological characteristics
and processes is relatively poor. As an initial attempt to describe the
dynamics and biology of the area, studies were conducted during the late
summer and early fall of 1973 on the biological, chemical and physical
characteristics, including measurement of nutrients and phytoplankton
productivity and the distribution and abundance of phytoplankton and
zooplankton. Only the physical and chemical variables will be discussed
here. For a more extensive and comprehensive treatment of the results
in this section, see Moll et al. (In press).
The purpose of this section is to show that multivariate statistical
techniques can be used to analyze large sets of data from the Great Lakes.
Specifically it will be shown that water masses can be identified from
cluster analysis of several variables. Data used are the same as those
discussed in Section III, except duplicate sampling of stations were not
used in the analysis. Several questions were studied: What is the
spatial relationship among stations? Was there an effect of depth on the
parameters sampled? Did the relationships among stations and depths vary
from cruise to cruise?
5.1 METHODS
For factor and cluster analyses, data were normalized to mean 0.0 and
variance 1.0 which reduces units for each variable to the same numerical
range (Pielou 1969). Computer programs used for cluster and factor
analysis are included in MIDAS (Michigan Interactive Data Analysis System),
statistical software at the University of Michigan Computing Center.
Several clustering algorithms were used, but the best results were obtained
with the unweighted pair group method (Sokal and Sneath 1963 or Sneath
and Sokal 1973).
56
-------
The relationship of each variable to other variables and the relative
importance of each variable were investigated with correlation analysis;
correlations calculated between variables were also used in a factor
analysis to show major factors affecting variability in the data (Van de
Geer 1971; Mulaik 1972). Only factor loadings with eigenvalues greater
than 1.00 were used (Rummel 1970). Values of the communalities for each
variable were estimated using the iterative principal axis factor solu-
tion (Harman 1967). Iteration was continued until succeeding estimates
of communalities differed by less than 1.0 x 10~3 or for 20 iterations.
An orthogonal varimax rotation was performed on the factor matrix.
Cluster analyses were run to determine the similarities between different
stations based on nine chemical and physical parameters. In the cluster-
ing analyses, the similarity coefficient between samples was either
Euclidean distances or correlation, with the Euclidean distances consis-
tently yielding higher cophenetic correlations. A cophenetic correlation
coefficient was calculated for every clustering analysis performed, and
only analyses with cophenetic correlations greater than +0.700 were
considered. The cophenetic correlation coefficient indicates the concur-
rence between the original distance matrix and the end result of the
clustering analysis (Sneath and Sokal 1973) . The only associations which
were considered of interest were those found in the lower half (based on
the number of branchings) of the phenogram. The hierarchy of station
relationships was displayed in the phenogram by circling clusters of
stations on a map of the sampling area.
5.2 RESULTS
Factor Analyses
Factor analysis determined the communality or the amount of variation
unique to each variable. A communality of 1.00 indicates the variation
was common to all variables sampled, while a value of 0.00 indicates no
variation common to the data set. In the Straits of Mackinac data
(Table 5.1), Secchi disc readings had the smallest communality (0.1399);
this result implied that the measure of Secchi disc values in this area
had little intrinsic value other than the knowledge of the Secchi disc
reading itself. Chlorophyll values also produced a low communality of
0.2226, which could have been in part explained by the absence of any
other phytoplankton biomass measures in the data set. Other communali-
ties in the data set were reasonably high.
Two factors were extracted from the factor analysis with eigenvalues of
3.8676 and 1.2366 (Table 5.1). The first factor showed an underlying
source of variation in the data composed of water temperature and pH, to
a lesser extent specific conductance and chlorophyll, and in the opposite
sign, silica and nitrate. This could have been considered a depth and/or
water mass factor. Silica and nitrate generally increased with depth
while temperature, pH, and to a lesser degree specific conductance de-
creased with depth. Likewise, water masses with high silica and nitrate
57
-------
Table 5.1. FACTOR ANALYSIS OF STRAITS DATA. N = 719, number of
factors = 2, Kaiser's statistic = .9328, where N = number of ob-
servations.
Variable
Communalities
Scaled factor loadings
(1) (2)
Secchi
Temp.
PH
Chlorophyll
Si02
NO 3
Total P
Sol P
Cond.
.13992
.78508
.90970
.22256
-.80841
-.78010
-.72711
.41525
.31606
Eigenvalue
% variance
-.37403
.88553
.95352
.40315
-.88669
-.88073
.06099
-.03489
.55223
3.8676
43.0
.00544
.03025
-.02228
.24500
. 14898
-.06652
.85052
.64345
-.10537
1.2366
56.7
had low temperature, pH, and specific conductance. The second factor,
apparently a phosphorus factor, had high loadings for both total and
soluble phosphorus. These results indicate three major factors influenced
the data set: depth, water masses, and phosphorus.
Cluster Analyses
Several groupings of data were used for clustering analyses: 1) all the
data from Cruise 1, 2) data from 0, 5, 10, 15, 20, 30, and 40 m for each
cruise, and 3) a reduced data set of water temperature, pH, silica,
nitrate and total phosphorus for 0, 5, and 10-m samples for each cruise.
Analysis of the entire data set for one cruise indicated that similari-
ties among stations were related primarily to depth and that the data
should be analyzed by depth.
Clusters of data for depths greater than 10 m were not reliable, as
cophenetic correlations were less than 0.700 and were therefore difficult
to interpret. Relatively few stations were deeper than 15 m, and data
from 20, 30 and 40 m were more homogeneous than surface waters so the
analysis had little value. Definite geographical patterns of stations
were obtained from clusters of data for 0, 5, and 10 m so these results
are discussed in the greatest detail. Clusters from the 15-m depth
showed a transition between the definite patterns found at 10 m and the
lack of obvious patterns at 20 m.
58
-------
Maps for Cruise 1 suggested a pattern of surface water flow from Lake
Michigan through the Straits, then south of Bois Blanc Island into Lake
Huron (Figs. 5.1-5.3). This flow pattern is indicated by the distribu-
tion of water masses. At the surface, one water mass extended from the
western edge of Mackinac Island to the southeastern edge of Bois Blanc
Island (Fig. 5.1). There were two additional large water masses of sur-
face water, one directly north of Bois Blanc Island and a second in the
northwest part of the study area. At 5 m, stations south of Bois Blanc
Island were joined with those west of the Straits, indicating a flow of
water south of Bois Blanc Island (Fig. 5.2). There was no indication
that the water mass north and northeast of Bois Blanc Island (Stations
27-37) was related to the water located south of the island and west of
the Straits. Winds during the cruise period were low in velocity and
from the southwest. Current meters set by the Great Lakes Environmental
Research Laboratory, NOAA, showed that water above 10 m flowed from Lake
Michigan south of Bois Blanc Island into Lake Huron (Saylor and Sloss,
In press).
On Cruise 2, Stations 38-50 were added to the sampling grid, but the
pattern of water masses was similar to Cruise 1. It was obvious that a
distinct water mass was found to the south and southeast of Bois Blanc
Island (Figs. 5-4-5.6); this water mass was also related to stations west
of the Straits. These data indicate that a related water mass extended
from stations west of the Straits in Lake Michigan to stations north of
Forty Mile Point in Lake Huron. Data for water temperature, specific
conductance, and nitrate-nitrogen (Table 3.1) indicated that this area
contained a mixture of Lake Michigan and Lake Huron water, with greater
proportions of Lake Michigan water on the west and of Lake Huron water on
the east. Current meters set by NOAA also showed that water flowed south
of Bois Blanc Island from Lake Michigan into Lake Huron.
Other areas of related stations were identified: First was the cluster
of Stations 47 and 48 (Figs. 5.4-5.6), obviously different from the other
stations in specific conductance, pH, silica, and nitrate (Table 3.1).
The chemical differences are due to the discharge of Lake Superior water
through Detour Passage. Second are the clusters of stations in the
northern part of the area. These east-west clusters were related to
upwelling along the northern shore that is evident at Stations 29-31
(App. C.14); this upwelled water can be traced along the northern shore,
as shown in Section IV.
The final cruise occurred during a period of east winds rather than the
prevailing westerly winds. More distinct patches or clusters of water
were identified during this cruise than from the previous cruises. A
distinct water mass was again present south of Bois Blanc Island, but it
was not connected to stations west of the Straits and appeared as a large
homogeneous area south of the island, extending southeast to Forty Mile
Point (Figs. 5.7-5.9). Two other water masses were evident, one com-
posed of stations surrounding Mackinac Island, the other of stations east
of Bois Blanc Island. Current meter data from the Straits showed little
surface flow of water into Lake Huron from Lake Michigan and a transport
from Lake Huron exceeding 30,000 m3 sec'1 on 6 October (Saylor and Sloss,
59
-------
AUGUST
SURFACE SAMPLES
Figure 5.1. SURFACE WATER DISTRIBUTION IN AUGUST. Only the strongest cluster associations are
shown.
-------
AUGUST
5 METER SAMPLES
Figure 5.2. FIVE-METER WATER DISTRIBUTION IN AUGUST. Only the strongest cluster associations
are shown.
-------
ho
AUGUST
\0 METER SAMPLES
84'OCT-
Figure 5.3. TEN-METER WATER DISTRIBUTION IN AUGUST. Only the strongest cluster associations
are shown.
-------
SEPTEMBER
SURFACE SAMPLES
-84'45'-
- 84-30'
Figure 5.4. SURFACE WATER DISTRIBUTION IN SEPTEMBER. Only the strongest cluster associations
are shown.
-------
SEPTEMBER
5 METER SAMPLES
-64'30'
Figure 5.5. FIVE-METER WATER DISTRIBUTION IN SEPTEMBER. Only the strongest cluster associations
are shown.
-------
Ln
SEPTEMBER
10 METER SAMPLES
-84-451-
-84-30'
84*15'-
-04'OCT-
Figure 5.6. TEN-METER WATER DISTRIBUTION IN SEPTEMBER. Only the strongest cluster associations
are shown.
-------
OCTOBER
SURFACE SAMPLES
-84*45'-
Figure 5.7.
shown .
SURFACE WATER DISTRIBUTION IN OCTOBER. Only the strongest cluster associations are
-------
LAKE ,.03
MICHIGAN |
I ** 1
02
OCTOBER
5 METER SAMPLES
I • 84*45' ' 64*30' 84*15' '—— 81'OCT '- '
Figure 5.8. FIVE-METER WATER DISTRIBUTIONS IN OCTOBER. Only the strongest cluster associations
are shown.
-------
00
AfSff
LAKE
MICHIGAN
OCTOBER
10 METER SAMPLES
Figure 5.9. TEN-METER WATER DISTRIBUTION IN OCTOBER. Only the strongest cluster associations
are shown.
-------
In press) . This 3-day period was unusual in that the flow from Lake
Michigan was small; however, on the day preceding the cruise (5 Oct.) the
transport from Lake Michigan to Lake Huron exceeded 50,000 m3 sec"1!
Thermal stratification was no longer present at Stations 01-06 and 13-23
on this cruise, as surface water temperature had decreased (Table 3.1).
A final series of clustering analyses was performed with a reduced data
set to determine the importance of certain key variables in the relation-
ships obtained from the complete data set. Clustering analyses from each
cruise for 0, 5, and 10-m samples were rerun using only water temperature,
pH, silica, nitrate, and total phosphorus—the variables identified as
major factors from the factor analysis (Table 5.1). Clusters produced
from the analysis of the reduced data set were generally comparable with
clusters from the full data set. For instance, surface samples from
Cruise 1 with a reduced data set showed clusters south and north of Bois
Blanc Island as well as a water mass west of Mackinac Island, just as
did the analysis using the full data set (Fig. 5.2). The results dif-
fered in that the cluster north of Bois Blanc Island was a little larger
in the reduced data set than for the full data set. Likewise, the full
data set showed the water mass west of Mackinac Island was related to
the mass south of Bois Blanc Island while the reduced data set did not
show this association. These differences between the full and reduced
data sets for the surface samples of Cruise 1 were typical of most compar-
isons between the full and reduced data sets. Results from the two data
sets were most similar on Cruise 3 and least similar on Cruise 1.
Comparison of all variables with variables identified as major factors
pointed out the pitfalls of sampling only a small number of parameters
to describe water masses. Under certain conditions (e.g., as the calm
winds during Cruise 3) both the full and reduced data sets gave the same
results. Under other conditions, different conclusions would have
resulted from analysis of the full data set than from analysis of the
reduced set. Certain variables can be considered "key" or major variables
all of the time with a good degree of reliability, but the interaction
between those major variables and other variables can rarely be predicted.
Due to unpredictable interactions, it is necessary to sample many varia-
bles to adequately describe water masses in unknown regions.
From results of all the clustering analyses, some general conclusions
about the Straits area could be made. A large, homogeneous area of water
extended from Lake Michigan into Lake Huron, although this area was
disrupted by winds from the east and southeast during the cruise. The
water mass extended generally from Lake Michigan through the Straits, past
the western shore of Mackinac Island and south of Bois Blanc Island.
Water characteristics were not greatly changed as the water mass passed
near the shore and over shallow areas south of Bois Blanc Island, although
there was evidence of greater proportions of Lake Huron water to the east-
ward. Water from Lake Huron was frequently identified at the extreme
central-eastern part of the sampling area (Stations 43, 44, 45) yet was
never associated with any water in the rest of the area. Water from the
69
-------
St. Marys River, identified by several chemical parameters, was released
into Lake Huron through Detour Passage. This water was identifiable only
at Stations 47 and 48 in the immediate vicinity of the passage. Most
water-mass associations were found only in the upper 10 m of the water
column, with the deeper water remaining unmixed with the surface waters,
except in areas of upwelling.
5.3 LITERATURE CITED
Federal Water Pollution Control Administration. 1967. Lake currents.
FWPCA, Great Lakes Region, Chicago.
Harman, H. H. 1967. Modern factor analysis. University of Chicago
Press. 474 p.
Henson, E. B. 1962. Notes on the distribution of the benthos in the
Straits of Mackinac region. Proc. 5th Conf. Great Lakes Res.,
Univ. Michigan, Great Lakes Research Div. Pub. 9: 174-175.
. 1970. Pontoporeia affinis (Crustacean, Amphipoda) in the
Straits of Mackinac region. Proc. 13th Conf. Great Lakes Res.:
601-610. Internat. Assoc. Great Lakes Res.
Moll, R. A., C. L. Schelske and M. S. Simmons. In press. Distribution
of water masses in and near the Straits of Mackinac. J. of Great
Lakes Res.
Mortimer, C. H. 1975. Physical characteristics of Lake Michigan and its
response to applied forces, p. 1-102. In Environmental status of
Lake Michigan region, Vol. 2. Argonne Nat. Lab., Argonne, 111.
ANL/ES-40.
Mulaik, S. A. 1972. Foundations of factor analysis. New York: McGraw-
Hill. 453 p.
Murty, T. S. and D. B. Rao. 1970. Wind-generated circulations in Lakes
Erie, Huron, Michigan, and Superior. Proc. 13th Conf. Great Lakes
Res.: 927-941. Internat. Assoc. Great Lakes Res.
Pielou, E. C. 1969. An introduction to mathematical ecology. New York:
Wiley-Interscience. 286 p.
Powers, C. F. and J. C. Ayers. 1960. Water transport studies in the
Straits of Mackinac region of Lake Huron. Limnol. Oceanogr. 5:
81-85.
Rummel, R. J. 1970. Applied factor analysis. Evanston: Northwestern
University Press. 617 p.
70
-------
Saylor, J. H. and P. W. Sloss. In press. Water volume transport and
oscillatory current flow through the Straits of Mackinac. J. Phys.
Oceanogr.
Sneath, P. H. A. and R. R. Sokal. 1973. Numerical taxonomy: The princi-
ples and practices of numerical classification. San Francisco:
W. H. Freeman and Co. 359 p.
Sokal, R. R. and P. H. A. Sneath. 1963. Principles of numerical
taxonomy. San Francisco: W. H. Freeman and Co. 359 p.
Van de Geer, J. P. 1971. Introduction to multivariate analysis for the
social sciences. San Francisco: W. H. Freeman and Co. 293 p.
71
-------
SECTION VI
DISTRIBUTION AND ABUNDANCE OF PHYTOPLANKTON
by
Eugene F. Stoermer, Russell G. Kreis, Jr. and
Theodore B. Ladewski
The major objective of this phase of the investigation was to determine
if there were consistent differences in the quantitative and qualitative
aspects of phytoplankton assemblages in Lake Michigan and Lake Huron and,
if so, to what extent populations developed in Lake Michigan were trans-
ported to Lake Huron. Available information (Schelske and Roth 1973;
Schelske 1975; Vollenweider et al. 1974) suggests that Lake Michigan is
more eutrophied than Lake Huron. It appears that eutrophication of Lake
Michigan has proceeded to the point where silica is becoming secondarily
limiting during summer stratification (Schelske and Stoermer 1971), re-
sulting in a shift of dominance in the phytoplankton assemblage from
organisms requiring silica to those which do not (Schelske and Stoermer
1972; Stoermer 1972). Possibly also secondarily related to eutrophica-
tion, Ladewski and Stoermer (1973) show that some areas of Lake Michigan
now have a midsummer transparency minimum similar to that observed in
Lake Ontario (Dobson et al. 1974). Satellite altitude images of Lake
Michigan (Strong et al. 1974) indicate that this phenomenon is probably
most highly developed in the southern and eastern portions of the lake.
Unfortunately, the area of our study is not included in the imagery
reported by the above authors.
Although comprehensive studies are lacking, those available (Stoermer and
Yang 1969; Schelske and Roth 1973; Schelske et al. 1974) indicate that
the phytoplankton assemblages of both northern Lake Michigan and northern
Lake Huron still retain elements of the oligotrophic Cyclotella flora
characteristic of large boreal and alpine lakes, including relatively
undisturbed portions of the Laurentian Great Lakes (Hutchinson 1967).
Due to the limited area covered by this investigation and the high prob-
ability of exchange and mixing between the two systems, effects in the
Straits of Mackinac region might be expected to be subtle and highly
time dependent. The evidence presented in this section, therefore,
should be viewed as representative of specific situations. While the
data presented may be representative of the general or average case, it
would be desirable to investigate other seasons of the year and specific
meteorological conditions.
72
-------
6.1 MATERIALS AND METHODS
The material utilized in this phase of the investigation was obtained
from the same stations and depths sampled for other parameters. At
stations where a thermocline was present, samples were taken from 0 and
5 m and from depths just above and just below the thermocline. At shal-
low stations, samples were taken from the first four depths sampled. In
addition to the stations sampled, a limited number of additional collec-
tions from the same time interval were inspected to confirm identity of
questionable taxa or to attempt to further determine occurrence patterns
of rare species. Immediately after collection in Niskin bottles, 50 nil
of water were fixed with 4% glutaraldehyde, stored at 4.0°C in the dark
for 1-4 hr toensure complete fixation and then filtered onto 0.8 ym
AA Millipore®, membrane filters (25 mm diameter). The filtered prep-
arations were subsequently partially dehydrated in an ethanol series,
cleared with beechwood creosote, and mounted on glass slides (Stoermer
et al. 1974).
All identifications and enumerations reported were made using a Leitz
Ortholux microscope fitted with an oil immersion objective and condenser
system furnishing 1.32 numerical aperture and approximately 1200 X magni-
fication. Population estimates were based on counting two 150-nm width,
transects 10 mm in length. Reference samples have been retained in our
laboratory.
Raw counts were coded and prepared so all data could be reduced by
computer. Initial data reduction furnished population estimates in the
form given in Table 6.1. Raw data in this form have been transmitted to
the project officer and are available upon request.
Principal component analysis (PCA) was chosen as a parametric multivari-
ate technique for analysis of phytoplankton cell concentrations. Untrans-
formed cell densities were used in the correlation matrix. Taxa for PCA
analysis were selected using three criteria. First, each taxon should
be well defined taxonomically—composite categories were avoided. Second,
each taxon should be counted with reasonable accuracy. Consequently it
was required that each taxon exceed 5 colonies or individuals in at least
one sample. Third, each taxon should be observed in at least 30% of all
samples, eliminating locally or erratically distributed taxa; it was
never applied directly since all taxa satisfying the second criterion
also satisfied this one. Fourteen taxa fulfilled these criteria for the
August and September cruises and 13 for the October cruise (Table 6.2).
Principal component analysis is a technique which reduces the number of
dimensions in multidimensional data and at the same time retains a maxi-
mum amount of information in the original multidimensional data set.
PCA performs the following operations on the data set. First, each
parameter (taxon abundance) is scaled to its standard deviation. This
allows taxa found in low abundances to be weighted equivalently to the
more abundant taxa. Second, each taxon is, in effect, assigned an axis
in a multidimensional Cartesian coordinate system, and each station is
assigned a location in the coordinate system relative to the abundances
73
-------
Table 6.1. EXAMPLE OF TABULATION OF PHYTOPLANKTON COUNTS.
EPJl Straits of Rackinac October 1973
project: EPA
year: 1973
station: 49
latitude: 45° 54.1'
nonber of cells counted: 367
diversity: 1.856
survey number: 3
Julian day: 280 ( 7 Oct)
depth: 5.0 m
longitude: 84° 02.6'
volume of water scanned: 0.477 ml
evenness: 0.557
division
Cyanophyta (blue-green algae)
Chlorophyta (green algae) . .
Bacillaciophy ta (diatoms) . .
Chrysophyta (chrysophytes). .
Cryptopbyta (cryptoraonads). .
Pyrrophyta (dinoflagellates).
other
undetermined.
total
number of
species cells/ml
0
2
19
3
2
1
0
_1_
"28
SE
CV X pop.
species name
Chrysosphaerella longispina
Fragilaria crotonensis. .
Asterionella formosa .
Cyclotella ocellata
Cyclotella stelligera ........
Dinobryon questionable sp. *1 . . . .
Rhodomonas minuta var. nannoplanctica
Undetermined cyst ..........
Helosira distans vars alpiqena. ...
Tabellaria fenastrata
Stephanodiscus ninut.us
Cyclotella nichiqaniana .
Ankistrodesnus sp. *3
Cryptomonas ovata ....
Rhizosolenia eriensis
Bitzschia acicularis
Oocystis questionable spp.. . . « . .
Jkchnanthes clevei var. rostrata ...
Knonoeoneis vitrea
Ceratiua hirundinella .
Cyclotella conta
Cyclotella meneghir.iana var. plana. .
Cyclotella operculata . .
Diploceis eliiptica var. pygnaea. . .
Diploneis cculata ....
tucocconeis lapponica ........
Hallononas pseudocoronata
Rhizosolenia gracilis
0.0
10.5
282.7
437.7
23.0
2.1
0.0
12.6
768.6
cells/ml
414.7
100.5
62.8
25. 1
20.9
20.9
16.8
12.6
12.6
12.6
10.5
8.4
6.3
6.3
6.3
4.2
ft. 2
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2. 1
2.1
2.1
2.1
0.0
2.1
85.9
123.6
2.1
2. 1
0.0
4.2
39.8
SE
104.7
92.2
12.6
8.4
4.2
20.9
4.2
4.2
12.6
12.6
2.1
0.0
2.1
6.3
2.1
4.2
4.2
2. 1
2.1
2. 1
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2.1
****
0.20
0.30
0.28
O.C9
1.00
****
0.33
0.05
CV
0.25
0.92
0.20
0.33
0.20
1.00
C.25
0.33
1.00
1.01
0.20
0.0
C.33
1.00
0.33
1.00
1.CO
'.CO
1.CO
1.00
1.00
1.0Q
1.00
1.00
l.CO
1.00
1.00
1.00
o.o
1.362
36.785
56.948
2.997
0.272
0.0
100.000
* pop.
53.951
13.079
8.17U
3.270
2.7.T5
2.725
2.180
1.635
1.635
1.635
1.362
1.090
0.917
0.817
0.817
0.545
0.545
0.272
0.272
0.272
0.272
0.272
0.272
0.272
0.272
0.272
0.272
0.272
74
-------
Table 6.2.
SPECIES AND DATA PROCESSING CODE FOR PHYTOPLANKTON USED IN THE
PRINCIPAL COMPONENT ANALYSIS.
Code
Taxon name
Type
Used in the
PCA for
Aug Sep Oct
ANINCE
ANTHER
ASFORM
CHDOKI
CNOVAT
CRQUAD
CYCOMT
CYMICH
CYSTEL
CYOCEL
CYOPER
ETSPEQ
GLPLAN
GMLACU
OOSPP
RDMINU
RHERIE
SYFILI
Anaoysti-s -Lnoerta
Anaeystis thermal'is
Asterionel~La foxmosa
ChicysoooQcus dokidophorus
Cryptomonas ovata
Grucigenia quadrata
Cyclotella oomta
Cyolotella miohiganiana
Cyelotella stell-lgeva
Cyolotella ooetlata
Cyclote'Lla apeveulata
Eutetramorus species #1
Gloeoeystis planktoniea
Gomphosphaeria lacustris
Oocystis spp.
Rhodomonas mlnuta v. nannoplanetica
Rh-Lzosolenia eirLensis
Synedra filiformis
Blue-green
Blue-green
Diatom
Chrysophyte
Cryptomonad
Green
Diatom
Diatom
Diatom
Diatom
Diatom
Green
Green
Blue-green
Green
Cryptomonad
Diatom
Diatom
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
of the taxa at that station. Stations with similar phytoplankton compo-
sitions, after the previously performed standardization, will in a
Euclidean sense be closer to each other in the multidimensional space than
stations dissimilar in composition. PCA projects the location of each
station in multidimensional space to a new set of mutually orthogonal axes
called principal components.
Associated with each taxon and principal component is a loading factor
which may be interpreted as the cosine of the angle the taxon's axis makes
with the principal component. The loading factor indicates how important
that taxon is in determining the principal component (PC) . The first axis
(the first PC) is chosen to contain the maximum possible variance and
thus will provide the best discrimination between stations of any of the
PCs. The second axis (second PC) contains the greatest variance possible
under the constraint of orthogonality with the first. The data set can be
completely described only by determining all principal components. If the
data set contains more stations than taxa, that number of PCs will be
equal to the number of taxa. However, if the first few PCs contain a.
large percentage of the variance, they will contain enough information to
justify ignoring all the rest for the sake of simplicity of interpretation.
Since the PCs are chosen to be orthogonal, scores of stations relative to
the principal components may be used as coordinates in a plot to show the
location of stations relative to one another. Relative locations of
75
-------
stations on the plot will roughly approximate relative locations of
stations in the multidimensional space. Stations very dissimilar in
composition may be identified and, to a somewhat lower degree of certain-
ty, very similar stations may be identified also on the basis of proxim-
ity on the plot. If only the first two PCs are retained, PCA reduces
the multidimensional data set to two dimensions. More complete descrip-
tions of the technique are given by Orloci (1966) and Morrison (1967) .
Additional information about the application of PCA to phytoplankton
cell densities is found in the discussion of results from October
(Sec. 6.4). Information on the cumulative percent variance, eigenvalue,
and statistical significance of each principal component derived from
the analysis of the August, September and October phytoplankton data is
presented in Table 6.3.
6.2 TAXONOMIC COMPOSITION OF THE PHYTOPLANKTON ASSEMBLAGE
A list of taxa encountered in this, study is given in Appendix D. Many of
the 289 taxa recorded are primarily benthic in habitat preference, and
their occurrence in plankton collections is probably accidental. As
would be expected, numbers of pseudoplankton were greatest at stations
nearest shore although some occurrences were noted in most samples
examined. Pseudoplankton was most common in the Detour Passage region
(Stations 46, 47, 48) where a large number of species apparently were
derived from the St. Marys River. Abundance estimates for most of these
taxa were small and subject to large errors, so primary emphasis has been
given to euplanktonic taxa in the analysis of data.
Bacillariophyta were the dominant organisms in the taxonomic listing,
comprising 222 of the 289 species and 34 of the 67 genera (Table 6.4).
Eight common genera accounted for 160 of the species of diatoms; only 62
species occurred in the other 26 genera of diatoms. Most species that
were not diatoms were Chlorophyta or green algae. Only five species of
blue-green algae were recorded.
Abundance of phytoplankton was greatest during the August cruise and
least during the October cruise, with relatively small variations in
total counts among stations during each cruise (Fig. 6.1). In September,
total counts were smaller at stations in the northeastern sector of the
sampling area than those on the most westerly transect and along the
southern shore. This difference in abundance was present in October, but
the range in total cell counts was smaller than in September.
The taxonomic composition of the phytoplankton also changed during the
study; the abundance of blue-green and green algae decreased during suc-
cessive sampling periods (Figs. 6.2 and 6.3). In both cases highest
numbers were found on the August cruise. Blue-greens and greens were
less abundant in September when the abundance of greens was very small.
76
-------
Table 6.3. RESULTS OF THE PCA OF 5-M PHYTOPLANKTON SAMPLES FOR THE
FIRST THREE PRINCIPAL COMPONENTS.
August
Number of samples: 39
Number of taxa: 14
PCI PC2 PC3
Cumulative % variance 29% 43% 55%
Eigenvalue 4.0 2.1 1.6
Significance21 .002 .025 .084
September
Number of samples: 32
Number of taxa: 14
PCI PC2 PC3
Cumulative % variance 34% 48% 60%
Eigenvalue 4.8 2.0 1.7
Significance .000 .002 .011
October
Number of samples: 40
Number of taxa: 13
Cumulative % variance
Eigenvalue
Significance
PCI
35%
4.5
.000
PC2
50%
2.0
.001
PC3
61%
1.4
.005
aThe significance values result from Bartlett's test of the hypothe-
sis that the determinant of the residual matrix is zero (eg. Cooley
and Lohnes 1971).
77
-------
Table 6.4. PHYTOPLANKTON IN THE STRAITS OF MACKINAC.
Species
Bacillariophyta 222
Chlorophyta 44
Chrysophyta 12
Cryptophyta 3
Cyanophyta 5
Pyrrophyta 3
Total 289
Genera
Bacillariophyta 34
Chlorophyta 21
Chrysophyta 4
Cryptophyta 2
Cyanophyta 4
Pyrrophyta 2
Total 67
Species of Common Bacillariophyta
Navicula 26
Nitzschia 26
Achnanthes 23
Fragilaria 22
Cyclotella 19
Synedra 18
Cymballa 16
Stephanodiscus 10
Total 160
78
-------
TOTBL flLGflL CaLS/HL
30 BUG - 1 SEPT 1973 -
TOTfll fiLCH. CELLS/H
17-19 SEPTEMBER 1973
TOTflL aCflL CELLS/M.
6-6 OCTOBER 1973
Figure 6.1. DISTRIBUTION OF TOTAL
ALGAL CELL COUNTS.
79
-------
BLUE-GREEN RLGRE CELLS/H.
17-19 SEPTEMBER 1973 *-*•
GREEN HLGflE CELLS/HL
30 BUG - 1 SEPT 1973 fl ' ' 'ofo
BLUE-GREEN ALGAE CELLS/HL
6-8 OaOBER 1973 •, . . >
GREEN flLCBE CELLS/ML
17-19 SEPTEMBER 1973
GREEN FUME CELJLS/ML
6-6 aTOBtR 1973
Figure 6.2. DISTRIBUTION OF BLUE-
GREEN ALGAE.
Figure 6.3. DISTRIBUTION OF GREEN
ALGAE.
80
-------
Blue-greens and greens tended to be more abundant at western stations
and those along the southern shore than at other locations. The abundance
of diatoms (Fig. 6.4) fluctuated much less drastically, and no clear pat-
terns were apparent in their occurrence.
6.3 DISTRIBUTION OF MAJOR SPECIES
Asterionella formosa is apparently an extremely eurytopic diatom, occur-
ring in a wide variety of habitats (Huber-Pestalozzi 1942) and thriving
under most conditions found in the Great Lakes. According to Hohn (1969)
it is one of the species whose absolute abundance did not change appreci-
ably in Lake Erie between 1938 and 1965. Scattered populations were
found in our August samples (Fig. 6.5) and no discernible pattern of
occurrence was apparent. Some increase in average abundance was noted in
September with an apparent tendency for highest population levels to occur
at stations nearest shore. In October, A. formosa was abundant at most
stations sampled but population levels remained low at offshore stations
in Lake Huron.
Cyclotella comta is a species widely reported from mesotrophic to oligo-
trophic habitats. It is common in the upper lakes but apparently absent
from Lake Erie (Hohn 1969) and exceedingly rare in Lake Ontario (Stoermer
et al. 1974). Populations were noted at all stations sampled during
August (Fig. 6.6), with highest abundance being found at stations on the
most easterly transect sampled. In September, relatively high population
levels were found at Stations 40-45 on the most easterly transect, not
sampled the previous month; but abundance was substantially lower at
stations west of this transect. Although still present at most stations
sampled during October, C. comta had declined to a relatively minor
element of the assemblage by this time and no marked trends in distribu-
tion were evident.
Cyclotella ocellata appears to be characteristic of relatively undisturbed
habitats in the Great Lakes (Stoermer and Yang 1970). Only a few isolated
populations were noted in August (Fig. 6.7), but it was quite abundant in
September at some stations in the northeastern sector of the area sampled.
Abundance of C. ocellata was more uniform in October than on the two
previous cruises. Our evidence suggests that this species maintains
metalimnetic populations during the summer, and population increases in
September and October are at least partially the result of upwelling and
metalimnetic entrainment.
Cyclotella operculata (Fig. 6.8) appears to have similar ecological
affinities to C. ocellata (Stoermer and Yang 1970). In our samples, it
is consistently less abundant than that species and, partially because of
the low population levels, its distribution pattern is not as clear. In
all months sampled, highest population levels were found at stations in
the eastern section of the sampling area.
81
-------
DIRTOM CELLS/ML
J7-19 SEPTEMBER 1973
DIATOM CELLS/ML
6-6 OCTOBER 1973
Figure 6.4. DISTRIBUTION OF DIATOMS,
82
-------
BSTEHIONELLfl FORMOSfl CELLS/ML
30 flUG - 1 SEPT 1973
ftSTERIONEU-fl FORMOSfl CELLS/ML
17-19 SEPTEMBER 1973 fr •
CTaOTELLfl COMTO CELLS/ML
30 flUG - 1 SEPT 1973
RSTERIONEOfl FORMOSfl CELLS/N.
6-8 OCTOBER 1973
CTOOTELLfi CBHTB CH.LS/HL
17-19 SEPTEMBER 1973 •
CTCLOTELLfl COHTfl CELLS/H.
6-8 OCTOBER 1973
Figure 6.5. DISTRIBUTION OF
ASTERIONELLA FORMOSA.
Figure 6.6. DISTRIBUTION OF
CYCLOTELLA COMTA .
83
-------
CYCLOTEtLfl OCELLflTfl CELLS/ML
30 HUG - 1 SEPT 1973
CtCLOTELLB OCELLflTfl CELLS/ML
17-19 SEPTEMBER 1973
CYCLOTELLR OCELLBTB CELLS/ML
6-8 XTOBER 1973 t
CTCLOTELLB OPBRCULBTfl CEUS/HL
30 BUG - 1 SEPT 1973 j
CTOOTaUB OPERCULflTfi CELLS/ML
17-19 SEPTEMBER 1973
craoraifl OPERCULBTB CELLS/ML \ •
B-8 OCTOBER 1973
Figure 6.7. DISTRIBUTION OF
CYCLOTELLA OCELLATA.
Figure 6.8. DISTRIBUTION OF
CYCLOTELLA OPERCULATA.
84
-------
Cyclotella michiganiana (Fig. 6.9) is very widely distributed in the
phytoplankton of the upper Great Lakes. Available evidence suggests that
it is tolerant of low levels of eutrophication but is eliminated from
habitats which have been grossly modified (Schelske et al. 1974). It was
fairly abundant and evenly distributed in August with an apparent trend
toward higher population levels at offshore stations in Lake Huron. This
pattern was reversed in September; population levels increased at stations
along the southern shore and on the Lake Michigan side of the Straits but
remained static or declined in the northeastern sector. The trend toward
higher populations in Lake Michigan was accentuated in the results from
the October cruise.
Cyclotella stelligera (Fig. 6.10) is a common component of the offshore
phytoplankton flora of the upper Great Lakes. Similar to C. michiganiana,
it appears to be favored by low levels of eutrophication and responds
strongly to experimental nutrient enrichment (Schelske and Stoermer 1972;
Schelske et al. 1972). Apparently, however, it is not tolerant of high
levels of pollution. Hohn (1969) lists it as one of the species that
decreased markedly in abundance in Lake Erie between 1938 and 1965. Its
abundance in Saginaw Bay (Schelske et al. 1974) and the nearshore waters
of Lake Michigan is reduced relative to less eutrophic open waters.
During August this species was present in remarkably uniform numbers at
most stations sampled. There was some tendency for higher values to
occur nearer the northern Lake Huron shore and the lowest values near the
southern shore. Abundance was greatest in September at all stations
sampled. By October, abundance decreased at stations in the northeastern
sector of the sampling area, but C. stelligera remained relatively abun-
dant at stations along the southern shore and on the Lake Michigan side
of the Straits.
Fragilaria crotonensis (Fig. 6.11) is one of the eurytopic plankton
dominants which apparently can tolerate the extreme range of environmental
conditions presently found in the Great Lakes. Similar to Asterionella
formosa, it did not show strong trends in regional or seasonal abundance
during the study. Interpretation of its distribution is complicated by
large uncertainties in population estimates resulting from patterns of
indeterminate colonial growth.
Synedra filiformis (Fig. 6.12) has not been widely reported from the
Great Lakes, and its distribution and ecological affinities are relatively
poorly known. It is apparently abundant in the offshore waters of Lake
Michigan (Stoermer and Yang 1970) and during the spring phytoplankton
maximum in Grand Traverse Bay (Stoermer et al. 1972). Published reports,
however, indicate that it is abundant only at stations near the mouth of
Saginaw Bay in Lake Huron (Schelske et al. 1974). In the present study,
its distribution was remarkable in that populations were largely restrict-
ed to stations along the southern coast and on the Lake Michigan side of
the Straits. Small populations were noted in the Detour Passage region
during September and October. This species was present in low densities,
but showed a general trend towards increased abundance during the period
studied.
85
-------
r
CYCLOTEUfi HICHIGRNIfWR CELLS/ML
30 BUG - I SEPT 1973 Q" ' ' IJQ
craoraLo NICHIGRNIM«I CELLS/ML
17-19 SEPTEMBER 1973
CTCLOTELLfl MICHIGfiNIflNB CELLS/ML
6-6 OCTOBER 1973 j—'—^-Jg0
Figure 6.9. DISTRIBUTION OF
CYCLOTELLA MICHIGANIANA.
CTCL07EU.fi STELLIGQV) CELLS^L
30 HUG - 1 SEPT 1973
CTCLOTELLfi STELLIGERfl CELLS/ML
17-19 SEPTEMBER 1973
CTCLOTELLfl STELLIGERR CELLS/ML
6-6 OCTOBER 1973 6"~*~~*~l3o
Figure 6.10. DISTRIBUTION OF
CYCLOTELLA STELLIGERA.
86
-------
FfWGILflfUR CRQTONENSIS CELLS/HL
30 RUG - 1 SEPT 1973
FROGIUWIfi OttJTONENSIS CELLS/ML
17-19 SEPTEMBER 1973
FIWGILPRIfl CROTONENSIS CELLS/ML
6-8 OCTOBER 1973 ft ' ' ',^Q
STNEOm FILIFORMIS CELLS/ML
30 flUO - 1 SEPT 1973 • i i
STNEORfl FILIFORHIS CELLS/ML
17-19 SEPTEMBER 1973
STNEORfl FILIFORMIS CELLS/ML
6-8 OCTOBER 1973 j—i—'—H-^
Figure 6.11. DISTRIBUTION OF
FRAGILARIA CROTONENSIS.
Figure 6.12. DISTRIBUTION OF
SYNEDRA FILIFORMIS.
87
-------
Rhizosolenia eriensis (Fig. 6.13) is one of the characteristic species
of phytoplankton assemblages in the upper Great Lakes. In recent decades
its abundance has been reduced in Lake Erie (Hohn 1969) and Lake Ontario
(Stoermer et al. 1974), but it continues to be a fairly important compo-
nent of assemblages in the upper lakes. The known distribution of R.
eriensis suggests that it is a summer ephemeral, developing transient
population maxima rapidly in regions where favorable conditions exist.
Only a few scattered occurrences of this species were noted in our August
samples. Population densities increased generally at stations sampled
during the September cruise, with largest increases noted in the north-
eastern and eastern segment of the region sampled. During the October
cruise, population densities remained relatively high with a more uniform
distribution than had been observed previously.
The genus TajbeJlaria is common throughout the Great Lakes system. A
number of growth forms are present (Koppen 1975), and at the present time
the precise taxonomic affinities of the populations which occur in the
Straits of Mackinac area are uncertain. In the present study we have
adopted the taxonomic criteria and nomenclature of Hustedt (1930) . Popu-
lations identified as T. fenestrata (Fig. 6.14) on this basis were rare
in samples from the August cruise, and the three occurrences, noted were
at stations north of Bois Blanc Island. Scattered populations were noted
in September samples and there was no readily discernible pattern of
occurrence. In October this entity had high levels of abundance at sta-
tions in the northern sector of the study area in Lake Huron, and it was
either present in very low densities or absent in the southeastern sector.
Scattered populations of Tabellaria fenestrata var. intermedia (Fig. 6.15)
were found at stations sampled during the August cruise, with no obvious
pattern of greatest abundance. During September it was noted only in
samples from the Detour Passage vicinity and at a few stations south of
Bois Blanc Island. A similar pattern of occurrence was noted in October,
but T. fenestrata var. intermedia was also present at stations west of
the Straits where it had not occurred the previous month.
Chrysococcus (dokidophorus Pasch.?), a species of questionable taxonomic
status, had an unusual temporal and areal distribution. It was not noted
during August (Fig. 6.16), but was present in most samples and locally
abundant in September. Largest populations in September were found in
open-water Lake Huron stations east and northeast of Bois Blanc Island,
but in October it was relatively abundant at most stations sampled, with
no obvious trend in its distribution. This species has not been reported
previously from the Great Lakes and its ecological affinities are very
poorly known.
Chrysophaerella longispina (Fig. 6.17) has rarely been reported from the
Great Lakes, but large populations were found at certain stations in
Lake Huron during October. Isolated populations were noted in August but
not in September. Its distribution is unusual in that occurrences were
restricted to stations east and north of Bois Blanc and Mackinac Islands.
88
-------
RHIZOSOLENlfl ERIENSIS CELLS/ML
30 HUG - 1 SEPT 1973 g—>-
RHIZOSOLENIR ERIENSIS CELLS/ML
17-19 SEPTEMBER 1973
RHIZOSOLENIR ERIENSIS CELLS/HL
6-8 OCTOBER 1973
Figure 6.13. DISTRIBUTION OF
RHIZOSOLENIA ERIENSIS.
89
-------
TflBELLflRlH FENESTRflTfl CELLS/ML
30. HUG - 1 SEPT 1973
TflBELLflRIfl FENESTRBTfl CELLS/ML
17-19 SEPTEMBER 1973
TOBELLRRIA FENESTRflTH CELLS/ML
6-6 OCTOBER 1973
FENESTOflTfl V. INTERMEDIflm.
30 HUG - 1 SEPT 1973
TflBELLflRlfl FENESTRflTfl V. INTEHMEOIfVML
17-19 SEPTEMBER 1973 fl '
TfiBELLflRIfi FENESTRfiTfl V. INTEBHEDIIVML
6-8 OCTOBER 1973
Figure 6.14. DISTRIBUTION OF
TABELLARIA FENESTRATA.
Figure 6.15. DISTRIBUTION OF
TABELLARIA FENESTRATA var.
INTERMEDIA.
90
-------
CHRYSOCOCCUS DOKIDOPHORUS / MLN
30 HUG - 1 SEPT 1973 0 ' * 30
CHRYSOCOCCUS DOKIDOPHORUS / MLN
17-19 SEPTEMBER 1973 g—«—'-^
CHRYSOCOCCUS DOKIDOPHORUS / ML\
6-6 OCTOBER 1973 ^ ' « ^
CHRTSOSPHREnaU) LONGISPINfl CELLS/ML
30 HUG - 1 SffT 1973 fl •< » ^
CHRTSOSPHRERELLB LONGISPINfl CaLS/HL
17-19 SEPTEMBER 1973 ^ » ' i^
CHRrSOSPHRERELLfl LONGISPINfl CaLS/ML
6-8 oaOBER 1973 fr ' ' i^
Figure 6.16. DISTRIBUTION OF
CHRYSOCOCCUS DOKIDOPHORUS.
Figure 6.17. DISTRIBUTION OF
CHRYSOSPHAERELLA LONGISPINA.
91
-------
Rhodomonas minuta var. nannoplanktonica (Fig. 6.18) is a common element
of phytoplankton assemblages in the Great Lakes. Its ecological affini-
ties are relatively poorly known, but it appears to be tolerant of
conditions in the offshore waters of Lake Ontario. (Munawar and Nauwerck
1971) as well as the upper lakes. During August, relatively large popu-
lations were found at stations north and east of Bois Blanc Island, with
smaller populations noted at many other stations. In September this
species was present at most stations sampled; highest populations were
found offshore in Lake Huron, and it was notably rare on the Lake Michigan
side of the Straits. Measurable populations were also found at most
stations sampled during October, however abundance appeared to be least
at stations in Lake Michigan and along both the northern and southern
shores.
Cryptomonas ovata (Fig. 6.19) seems to be a ubiquitous member of phyto-
plankton assemblages from all regions of the Great Lakes. It was present
in nearly all samples taken during this study and exhibited no pronounced
patterns in either seasonal or areal distribution.
Species of Ankistrodesmus (Fig. 6.20) are common elements of phytoplankton
assemblages in the Great Lakes. Several species are apparently present
in all the lakes and some, such as A. falcatus, reach relatively high
population levels in eutrophied areas (Stoermer et al. 1974). The iden-^
tity and ecological affinities of the particular species most abundant
in the study area are unknown. It was present at most stations sampled
throughout the study and was particularly abundant along the southeastern
shore in September and October.
Crucigenia quadrata (Fig. 6.21) is a common minor element of the offshore
phytoplankton of many areas of the Great Lakes during the summer. In our
experience, population levels as high as those found in the present study
are unusual. Populations generally declined during the three months
sampled, and there was a slight trend toward higher population levels at
stations near Bois Blanc and Mackinac Islands.
Eutetramorus sp. (Fig. 6.22) was a numerically important member of assem-
blages collected in August, when it was quite abundant and very evenly
distributed over the sampling area. By September these populations had
disappeared, with only isolated minor populations remaining at stations
in the southwestern sector. Only a few isolated populations were noted
in the October samples. The ecological affinities of this organism are
unknown and it has not been reported from the Great Lakes previously.
Gloeocystis planctonica (Fig. 6.23) was present at most stations sampled
in August, and there was a trend toward higher population levels on the
Lake Michigan side of the Straits and near Mackinac and Bois Blanc Is-
lands. Abundance of this species was reduced considerably in September
and October. Our observations indicate that it is a characteristic
member of summer phytoplankton associations in southern Lake Michigan
that develop when diatoms are silica-limited.
92
-------
RHOOOMONRS HINUTfl V. NBNNOPUWCTICfl/ML
30 RUG - 1 SEPT 1973 0 ' '
RHOOOHONflS MINUTfl V. NfiKHOPLflNCTICfl/ML
17-19 SEPTEMBER 1973
RHODOHONRS NINUTB V. NflNNOPUtCTICfl/ML
6-6 OCTOBER 1973
CRYPTOMONflS OVHTfl CELLS/ML
30 flUG - I SEPT 1973 ' < '
CflTPTOMONBS OVBTfl
17-19 SEPTENBER 1973
CRTPTOMONRS OVPTH CELLS/ML
6-8 OCTOBER 1973
Figure 6.18- DISTRIBUTION OF
KHODOMONAS MINUTA var. NANNO-
PLANCTICA.
Figure 6.19. DISTRIBUTION OF
CRYPTOMONAS OVATA .
-------
RNKISTRODESMUS SPECIES *3 CELLS/ML
17-19 SEPTEMBER 1973
CRUCIGENIA QUfiOHflTfl CELLS/ML
30 BUG - 1 SEPT 1973 ' '
CRUCIGENIH OUflORflTfl CELLS/ML
17-19 SEPTEMBER 1973 ft • •
flNKISTPOOESMUS SPECIES «3 CaLS/ML
6-8 OCTOBER 1973
CRUCIGENIH QUHORflTR COLS/ML
6-e ocToeen 1973
Figure 6.20. DISTRIBUTION OF
ANKISTRODESMUS species #3.
Figure 6.21. DISTRIBUTION OF
CRUCIGENIA QUADRATA.
94
-------
EUTEWBHOBUS SPECIES »1 CELLS/Ml
30 BUG - 1 SEPT 1973 t •—
GLOEOCTST1S PtfllCTONICfi CELLS/ML
30 RUG - 1 SEPT 1973 0 • •
SPECIES «i CELLS/HI
17-19 SEPTEMBER 1973 t
GLOEOCTSTIS PLflNCTONICfl CEILS/ML
17-19 SEPTEMBER 1973 ' • '
GLOEOCTSTIS PLflNCTONICfl CELLS/ML
6-8 OCTOBER 1973
EUTETFttMORUS SPECIES «1 CELLS/HL
6-8 OCTOBER 1973
Figure 6.22. DISTRIBUTION OF
EUTETRAMORUS species #1.
Figure 6.23. DISTRIBUTION OF
GLOEOCYSTIS PLANCTONICA.
-------
Although somewhat less abundant than Gloeocystis, species of Oocystis
(Fig. 6.24) had a similar pattern of distribution. Measurable popula-
tions were found at all stations sampled during August, and there was a
definite trend toward higher population levels in the southwestern
sector of the sampling area. Average population abundance was reduced
in September, and there was a weak trend toward higher population levels
at stations in Lake Michigan and along the southern shore. Population
levels were further reduced in October but the same trend in distribution
was apparent. Members of this genus are widely distributed in summer
phytoplankton assemblages from the upper Great Lakes but, like
Gloeocystis, it appears to be favored when diatoms are silica-limited
and it has become more abundant in southern Lake Michigan in recent years.
Anabaena flos-aquae (Fig. 6.25) is a common minor constituent of summer
phytoplankton assemblages in the Great Lakes. It is one of the eurytopic
species favored by eutrophication and has the potential for forming nui-
sance blooms under nutrient-rich conditions. Its pattern of indetermi-
nate colonial growth leads to rather large uncertainties in abundance
estimates. Isolated populations were noted in August, and it was most
consistently present at stations in the southwestern sector of the
sampling area. Reduced population levels were noted in September at
stations on the Lake Michigan side of the Straits and along the southern
shore. A similar situation was found in October, except several sizable
populations were also found at offshore stations in Lake Huron.
Anacystis incerta (Fig. 6.26) is a common element of summer and fall
phytoplankton assemblages throughout the Great Lakes. It is usually not
abundant in the upper lakes but has the potential for forming nuisance
blooms because of its large colonies and the presence of gas vacuoles in
the cells (Drouet and Daily 1956). It was the most abundant member of
assemblages collected in August and tended to be especially abundant at
stations in the southwestern sector of the sampling area. In September
it remained abundant at stations on the Lake Michigan side of the Straits
and along the southern shore, but only relatively minor populations were
found in the rest of the area sampled. In October small populations
were restricted to stations on the Lake Michigan side of the Straits and
along the southern shore.
Anacystis thermalis (Fig. 6.27), like the previous species, is a common
element of summer phytoplankton assemblages in the Great Lakes. It does
not, however, have the potential to produce nuisance blooms since the
colonies are small and the cells lack gas vacuoles. Our observations
indicate that it also has a different ecologic range than A. incerta.
It apparently is favored by low levels of eutrophication and has become
much more abundant in southern Lake Michigan in recent years. It appar-
ently cannot tolerate gross perturbation. Anacystis thermalis is either
present in very low numbers or absent from areas such as Saginaw Bay and
western Lake Erie and is much less abundant than A. incerta in Lake
Ontario (Stoermer et al. 1974). It was present at all stations during
August and tended to be most abundant in the southwestern sector of the
96
-------
OOCTSTIS SPP. CELLS/ML
30 HUG - 1 SEPT 1973 ft • • ^
flNflBflENfl FLOS-flQUHE CELLS/ML
30 MJG - 1 SEPT 1973 g-
RNflBflENfl FIOS-flQUflE CELLS/ML
17-19 SEPTEHBEfl 1973 • «
OOCTSTIS SPP. CELLS/ML
17-19 SEPTEMBER 1973 g—'—•-fa
WRBflENR aOS-BQUBE CELLS/ML
6-8 OCTOBER 1973
OOCTSTIS SPP. CELLS/ML
6-8 OCTOBER 1973
Figure 6.24- DISTRIBUTION OF
OOCYSTIS SPP.
Figure 6.25. DISTRIBUTION OF
ANABAENA FLOS-AQUAE.
97
-------
HNRCtSTIS INCERTfl CELLS/ML
30 flUG - 1 SEPT 1973
flNRCTSTIS INCERTB CELLS/ML
17-J9 SEPTEMBER 1973 g—•—Hg^
flNflCTSTIS INCERTfl CELLS/ML
6-8 OCTOBER 1973
7
flNflCTSTIS THERMflLIS CELLS/ML
30 HUG - 1 SEPT 1973 Q ' * 300
flNflCTSTIS THERMBUIS CaLS/ML
17-19 SEPTEMBER 1973 ^ • • 3fo
flNflCTSTIS THERMflLIS CatS/HL
6-8 OCTOBER 1973
Figure 6.26. DISTRIBUTION OF
ANACYSTIS INCERTA.
Figure 6.27. DISTRIBUTION OF
ANACYSTIS THERMALIS.
98
-------
sampling area. In September, population levels were low at offshore
stations in Lake Huron but remained abundant on the Lake Michigan side of
the Straits and along the southern shore. In October, population levels
comparable to those found previously occurred only at stations on the
Lake Michigan side of the Straits, and only relatively small populations
were found in Lake Huron with greatest abundance along the southern
shore.
Gomphosphaeria lacustris (Fig. 6.28) is a common element of phytoplankton
communities in the Great Lakes. It is apparently eurytopic and tolerates
the range of conditions between Lake Superior and Lake Ontario. Its
abundance is reduced in grossly perturbed areas such as the inner reaches
of Saginaw Bay. It was most abundant in August but no obvious trends in
distribution were apparent. In September it was most abundant on the
Lake Michigan side of the Straits and along the southern shore. Some
indication of the same distribution pattern as September was evident in
October although occurrences were more scattered with smaller ranges in
populations.
Scattered populations of Oscillatoria bornetii (Fig. 6.29) were noted in
the samples from all three cruises. This species tended to increase in
abundance, especially in October, but no strong trends in areal distri-
bution were apparent.
6.4 ORDINATION ANALYSIS OF PHYTOPLANKTON ASSEMBLAGES
Data on ordination analysis of phytoplankton are presented in the reverse
order of collection, as the October cruise comprises the most complete
data set. In October all 50 stations were sampled, whereas Stations
38-50 were not sampled in August and Stations 32-37 were not sampled in
September.
Wear-surface Associations in October
The ordination analysis of October samples revealed an east-west or
Lake Huron-Lake Michigan axis for the first principal component (PC).
Stations in region Ax found on the extreme right end of the first PC
were generally located west of the Straits, and stations in regions B,
BC, and C on the opposite end of the first PC were located generally
northeast of the Straits (Fig. 6.30a). Region A2 was composed of sta-
tions located between the two extremes. Since the first PC removes the
greatest variance from the data, it may be concluded that the greatest
difference in surface phytoplankton communities was between the communi-
ties found in Lake Michigan and those found east of the Straits.
A plot (Fig. 6.30b) of the 13 taxa used in the principal component
analysis (PCA) relative to the loading factors of the first two PCs il-
lustrates the composition of the communities for various regions
99
-------
GOHPHOSPHfiERIft LflCUSTFUS CELLS/HL
30 BUG - 1 SEPT 1973 ^ ' ' tgbo
GOMPHOSPHflERIR LflCUSTRlS CEULS/HL
17-19 SEPTEMBER 1973 ^ • • ^
OSCILLBTOR1B BORNETII CELLS/HL
OSCILLfiTORIR BORNETII CELLS^IL
17-19 SEPTEMBER 1973
OSCILLflTORIR BOmETII CELLS/HL
6-8 OCTOBER 1973 ., . . . .
GOMPHOSPHREftlfi LfiCUSTRIS CELLS/ML
6-6 OCTOBER 1973
Figure 6.28. DISTRIBUTION OF
GOMPHOSPHAERIA LACUSTRIS.
Figure 6.29. DISTRIBUTION OF
OSCILLATORIA BORNETII.
100
-------
(a)
(WEB1E-*
CTCOHIJ
(b)
Figure 6.30. OCTOBER 5-M SAMPLE ORDINATION PLOTS. The first principal component is represented on the
horizontal axis and the second on the vertical axis. The cross indicates the location of the ori-
gin. The exact location of the station or taxon is at the lower left-hand corner of its label.
(a) Station ordination plot. Stations are located relative to the first two principal component
scores. See Figure 2.1 or Figure 6.31 for station locations.
(b) Phytoplankton taxa ordination. Taxa are located relative to the loading factors of the first
two principal components. See Table 6.2 for the taxa abbreviations. The small letters following
the taxon abbreviation indicates the division: diatom, chrysophyte, j»reen, b_lue-j»reen, cryptomonad.
-------
depicted in Figure 6.31. A station with relatively high densities of
taxa located on the right side of Figure 6.30b will be located on the
right side of Figure 6.30a, or any station with relatively low densities
of these taxa on the right side of Figure 6.30b will be situated on the
left side of Figure 6.30a. Similarly, any station with high densities
of species at the top of Figure 6.30b will appear toward the top of
Figure 6.30a, but if it has low densities of these taxa it will appear
toward the bottom of Figure 6.30a. The cluster labeled "Z" (Fig. 6.30b)
defines a community of four species with similar patterns of distribution
corresponding to region C (Fig. 6.31). These species tend to be abundant
in the same places, and where these species are abundant the taxa of
community X and community Y (Fig. 6.30b) are relatively rare. Conversely,
where the taxa of community X are abundant, those of Z and Y are rare.
Likewise stations of region AI would tend to have high concentrations of
the taxa of community X.
Two species, Rhizosolenia eriensis and Cyclotella comta, have relatively
small loading factors for both the first and second component, i.e.,
they appear close to the origin (Fig. 6.30b). These species apparently
show no clear distribution patterns relative to the others or occur in
equally high abundances in more than one of the regions Aj , B and C. It
might also be expected that, although Chrysococcus dokidophorus appears
to belong to community Z, its relatively high loading factor for PCj
indicates that it may also be found in region Aj as well as in region C.
Community Y is represented by only one species, Asterionella forwosa and
it would be found primarily in region B.
Regions containing characteristic phytoplankton communities as identified
on the basis of the ordination plots (Fig. 6.30a) have been plotted in
Figure 6.31. This map suggests a close geographical proximity between
stations with similar phytoplankton communities. The similarity between
Figures 6.31 and 4.2 suggests that the grouping is determined primarily
by water currents.
Hypolimnetic Associations in October
A PCA was performed for all samples collected in October, including the
5-m as well as a small number of hypolimnetic samples (Fig. 6.32a).
Regions Aj, A2, EI and C are based on the results of the PCA for the 5-m
samples as shown in Figure 6.30a; relative positions of these regions
have been changed little by including hypolimnetic samples in the analy-
sis. A new group of stations, region D (Fig. 6.32a) corresponds to
hypolimnetic samples collected east and north of Bois Blanc Island in
Lake Huron. Associated with region D is a phytoplankton assemblage, W,
consisting of Cyclotella ocellata and Rhizosolenia eriensis. This hypo-
limnetic association can be distinguished from assemblage Z found in the
surface water which is characterized by Rhodomonas winuta v.
nannoplanctica, Cryptomonas ovata and Chrysococcus dokidophorus.
102
-------
-84°45'-
-84°30'
84°I5'-
-84-OCT-
Figure 6.31. GEOGRAPHIC LOCATIONS OF 5-M OCTOBER PHYTOPLANKTON COMMUNITIES. Regions are deter-
mined on the basis of the ordination plot of Figure 6.30. Phytoplankton data are not avail-
able for stations not included in one of the four regions.
-------
(a)
CYCOMT
Figure 6.32. ORDINATION PLOTS FOR OCTOBER SURFACE AND SUBSURFACE SAMPLES.
(a) Station ordination plot. The number preceding the hyphen refers to the station, and the number
following the hyphen refers to the depth in meters at which the sample was taken. Unhyphenated num-
bers refer to samples collected at 5 m. Samples are located relative to the first two principal
components.
(b) Phytoplankton taxa ordination. Taxa are located relative to their loading factors. The first
principal component is represented on the horizontal axis and the second on the vertical axis. See
caption for Figure 6.30a and b for further explanation.
-------
The assemblages in surface and hypolimnetic samples from stations in
Lake Michigan were similar. Subsurface samples taken at Stations 03 and
15 appeared to have the same phytoplankton community as the 5-m samples
(Fig. 6.32a).
Total cell densities are highest at the surface and lowest in the hypo-
limnion, but diatom densities are highest below the thermocline at
Station 29 (Table 6.5). Diatoms constitute 15% of the assemblage at 0 m
for Station 29 but 93% of the assemblage below the thermocline at 50 m.
Results of the ordination analyses are qualitative and may be considered
ambiguous; the differences, however, between standing crops of different
species of phytoplankton in each region also can be evaluated from the
average standing crops. It can be seen that the six species identified
as community X in region Aj (Fig. 6.32b) by ordination analysis are those
that were more abundant in region X than in the other regions (Table 6.6).
Cyclotella ocellata and Rhizosolenia eriensis, the hypolimnetic assem-
blage W, from Lake Huron had the greatest cell densities in region D
(Table 6.6).
Stations with unusual or extreme communities on the basis of the ordina-
tion plot are 06, 42 and 31 (Fig. 6.30a). Station 06, located NW of the
Straits, had near-surface cell densities for Cyclotella stelligera,
C. michiganiana, and Synedra filiformis that were at least three times
more abundant than at any other station (Table 6.6). It also had
extremely high densities of Fragilaria crotonensis, a species not used
in the PCA, and Rhizosolenia eriensis. Station 06 had the highest near-
surface cell densities for total algae, total blue-greens, and total
diatoms of all stations sampled in October. Station 42, SE of the
Straits, had the highest 5-m cell density for Cyclotella operculata but
also had extremely high densities of Cryptomonas ovata, Chrysococcus
dokidophorusf Rhodomonas minuta var. nannoplanctica and Cyclotella
stelligera. Station 31, located in the northcentral part of the survey
area, had the highest 5-m density of all stations for Asterionella
forwosa and high density of Fragilaria crotonensis but also, by contrast,
had extremely low concentrations for a number of species including
Chrysococcus dokidophorus, Cyclotella stelligera, Rhodomonas minuta var.
nannoplanctica, Anacystis incerta, and Anacystis thermal is.
Near-surface Associations in September
The ordination plots for September (Fig. 6.33) were analyzed from a
smaller set of samples and are therefore more difficult to interpret than
those for October (Figs. 6.30 and 6.32). Plots for September do not show
the well segregated clusters found in October. Station 39 had a particu-
larly unusual phytoplankton assemblage which included very high densities
of Anacystis incerta, A. thermal is, Cyclotella michiganiana, characteris-
tic of region Aj (Fig. 6.33a), and Rhodomonas minuta var. nannoplanctica,
and Chrysococcus dokidophorus which were more abundant in the northeastern
corner of the survey area. Inclusion of Station 39 with region A2 is
therefore somewhat arbitrary.
105
-------
Table 6.5. CELL DENSITIES AT STATION 29 ABOVE, IN, AND BELOW THE THERMOCLINE FOR THE AUGUST, SEPTEMBER AND OCTOBER CRUISES.
Letters "E," "T" and "H" refer to epilimnion, thernocllne, and hypolinmion. Under "apparent trend" Is indicated the regions in
which a taxon attains highest densities. Under "dep" is indicated the depth which, at Station 29, the taxon appears to be
concentrated. This determination is made subjectively on the basis of the cell densities at Station 29. Under "epi" is the
surface region where the taxon is most abundant as indicated on Tables 6.6, 6.7 and 6.8. For each taxon, cell densities (in
cells/ml) are given above the standard error of the mean, which is determined on the basis of a replicate cell count of the
sample.
August
Anacystis incerta
Anacystis thermal is
Synedra filiformis
Cyclotella michiganiana
Cyclotella stelligera
Oocystis spp.
Gloeocystis planctonica
Cruc-igenia guadrata
Cyclotella comta
Chrysococcus dokidophorus
Kh-izosolenia eriensis
Eutetraoorus species #1
Anabaena flos-aquae
Fragilaria crotonensis
Tabellaria fenestrata
Cyclotella operculata
Asterionella foroasa
Cryptononas ovata
Chrysosphaerella longispina
Rhodomonas minuta v.
nannoplanctica
Cyclotella ocellata
Total cells/ml
Total blue-green cells/ml
% blue-green
Total green cells/ml
% green
Total diatoms/ml
% diatoms
Temperature (°C)
Conductivity (umho/cn)
E
Om
1697
691
0
0
65
6
607
398
23
19
80
34
40
23
92
92
23
11
0
0
260
38
354
138
136
2
6
6
0
0
0
0
2
2
0
3424
2656
78
499
15
264
8
21.5
226
Sample depth
ETH
5m
3288
649
111
52
2
2
52
11
880
335
31
2
55
78
2
0
50
13
0
6
6
335
21
262
262
6
6
0
6
2
0
11
2
0
23
2
4
4
5408
4616
85
519
10
205
4
21.0
228
20m
147
147
0
0
69
2
607
189
73
6
21
8
38
21
0
82
19
0
19
6
34
34
0
293
75
4
4
8
4
0
0
0
8
4
82
6
1539
754
49
96
6
679
44
9.0
202
50m
105
105
0
19
2
17
8
0
0
44
15
0
0
0
13
4
0
0
0
0
0
4
4
0
0
0
0
27
11
300
105
35
0
0
195
65
4.5
218
Apparent
trend E
dep epi Om
E A 712
E A 67
H I 4
4
E BC 21
13
E C? 335
335
T C 130
4
E A 15
2
E A 0
? A 0
IB 13
1 1 17
4
T ? 0
E A 0
E A? 0
1 C 159
113
? ? 0
? B 0
? C 0
E ? 4
? ? 0
E BC 19
6
T C 124
36
1711
1114
65
23
1
532
31
10.6
216
September
Sample depth
ETH
5m
838
545
63
4
0
50
21
147
147
128
27
65
6
36
36
0
27
2
27
11
4
0
0
90
69
13
8
0
0
8
4
0
13
4
115
10
1690
1047
62
111
7
482
29
10.6
216
20m
168
168
34
34
0
61
19
0
128
2
13
4
8
8
0
61
6
6
2
19
15
19
2
0
82
82
2
2
0
0
6
2
0
8
8
245
44
1273
545
43
48
4
658
52
8.0
207
50m
314
63
0
6
2
2
2
0
140
2
13
13
17
0
21
0
52
6
0
0
191
48
2
2
0
0
2
2
0
2
2
352
38
1357
404
30
107
8
840
62
5.8
214
Apparent Sample
trend E E
dep epi Om
E A 0
E A 272
272
? ? 0
ET A 4
E A 0
ETH AB? 23
6
E A 13
13
? A 25
25
? ? 0
T C 2
2
E ? 8
4
H C 0
T A 0
? ? 0
? ? 48
19
11 2
2
1 C 2
2
? A 0
? ? 6
2
? ? 484
182
E ? 17
H C 61
15
984
272
28
48
5
149
15
10.6
216
5m
21
21
0
0
8
4
168
168
23
2
4
0
0
8
4
21
4
2
2
0
46
46
124
40
0
2
2
29
29
15
2
375
358
25
17
88
21
1066
331
31
6
.6
293
28
10.6
216
October
depth
T H
20m
105
63
8
0
15
2
0
17
4
6
6
25
25
0
2
2
15
2
4
4
0
0
147
96
6
6
2
2
57
31
8
8
0
4
4
124
44
771
251
33
52
7
400
52
6.0
71?
50m
21
21
0
4
11
6
0
36
15
0
0
0
13
4
4
13
13
0
0
191
191
4
2
2
0
6
6
0
2
2
157
27
522
21
4
0
0
486
93
4.6
719
Apparent
trend
dep epi
T A
1 A
? A
TH A
? A
ETH A
? A
? A
? A?
H AC
E AC
H ?
7 ,
? ?
? ?
? ?
? ?
T B
E C
E C?
E C
H C
106
-------
Table 6.6. OCTOBER PHYTOPLANKTON CELL DENSITIES. Average densities (in cells/ml) for each
region (Figs. 6.30a and 6.31) are given over the standard error of the mean. Standard errors are
omitted when values used in the average are identical. Columns titled "apparent trend" indicate
regions of maximum and minimum abundance. Taxa are grouped according to apparent trend. Taxa
most abundant in region AI are listed first, those showing no pattern relative to the regions are
listed second, and those taxa most abundant in regions B or C are listed last. Taxa identified
with an (*) were used in the PCA.
Region label and Number of stations ADDarent trpnri
Anacystis incerta*
Anacystis tbermalis*
Synedra filiformis*
Cyclotella michiganiana*
Gomphosphaeria lacustris
Cyclotella stelligera*
Oocystis spp.*
Gloeocystis planctonica
Crucigenia quadrata
Cyclotella comta*
Chrysococcus dokidophorus*
Rhizosolenia eriensis*
Eutetramorus species #1
Anabaena flos-aquae
Fragilaria crotonensis
Tabellaria fenestrata
Cyclotella operculata
Asterionella formosa*
Cryptoinonas ovata*
Chryaosphaerella longispina
Rhodomonas minuta v. nannoplanctica*
Cyclotella ocellata*
AI
5
1114
88
126
13
24
11
95
14
394
82
85
21
21
6
12
8
19
12
11
2
17
2
10
4
3
3
37
23
103
74
8
3
2.1
.9
28
4
5.4
.5
0
5
2
43
7
A?.
10
494
107
30
6
10
2
48
7
276
51
58
5
16
2
5
3
23
8
11
2
16
2
8
2
6
3
16
8
49
18
3.8
.8
1.7
.8
27
5
5
1
34
24
5
2
47
6
B
10
31
31
8
3
.8
.6
12
3
134
38
24
6
5
1
.8
.8
0
6
1
8
1
6
2
0
21
18
168
49
6
2
3
1
41
7
5.4
.7
100
48
11
2
38
5
BC
10
170
63
16
4
.6
.3
12
2
300
78
25
4
7
2
.6
.6
16
16
5
1
16
1
8
2
7
3
11
9
67
15
6
2
1.5
.9
28
7
5.9
.8
67
38
18
4
75
7
C
5
256
110
18
9
2
2
14
2
67
34
54
21
5
2
2
2
0
12
2
21
3
7
2
3
3
62
52
65
19
4
4
5
3
21
6
10
2
245
150
33
7
121
16
D
8 High Low
20 A B,D
15
27 A B
20
9 A B,C
2
14 A
1
168 A C
89
42 A B
7
10 A
3
16 A B
15
4 A?
4
10 A,C,D
1
5.5 A,C B,D
.8
17 D
4
5
3
0 D
86
22
9
3
1.6
.5
18 B
7
4 C
1
0 C? A,D
3 D A.D
1
142 C,D
19
107
-------
o
oo
(a)
(b)
Figure 6.33. SEPTEMBER 5-M WATER SAMPLE ORDINATION PLOTS. See Figures 6.30a and 6.31 for further dis-
cussion. Station locations are given on Figure 6.34. Communities shown are chosen with the help of
Table 6.5.
(a) Station ordination plot.
(b) Phytoplankton ordination plot.
-------
Comparison of the phytoplankton distribution in September (Fig. 6.34)
with that of October shows that the general orientation and locations of
regions A, B, and C were similar in the two months. The species composi-
tion of community X for September (Fig. 6.33b) is similar to community X
in October; both are characteristic of region AX and A2 (Lake Michigan
water) and have several species in common: Anacystis incerta,
A. thermalis, Cyclotella michiganiana, Oocystis spp., and Gomphosphaeria
lacustris (Tables 6-6 and 6.7).
Community Z for September, consisting of two diatoms, Cyclotella comta
and C. operculata, is quite different from community Z for October which
includes a diatom, chrysophyte, and two cryptomonads. These Z communities
are found in region C which is located in approximately the same area for
the two cruises. Community Y in September consists of Cyclotella ocellata
and Rhizosolenia eriensis, which corresponds with the hypolimnetic
community W of October.
Hypolimnetic Associations in September
Ordination plots for stations and taxa of all 5-m samples plus some
selected hypolimnetic samples show an overlap of samples in regions B
and D (Fig. 6.35). Community Y, consisting of Cyclotella ocellata and
Rhizosolenia eriensis, is found in both regions, indicating that upwelled
water is present at the surface in region B. In this deep water region
(Table 6.7), C. ocellata and R. eriensis attain extremely high densities
and are the only taxa more abundant below the thermocline than above it.
Near-surface Associations in August
In August, region Aj in Lake Michigan combined with region A2 has a phyto-
plankton assemblage, X, that is similar to that found in September and
October except that it contains no diatoms (Fig. 6.36). Two blue-green
algal taxa (Anacystis incerta and A. thermalis) and four green algal taxa
(Gloeocystis planctonica, Crucigenia guadrata, Oocystis spp- and a
Eutetramorus species) dominate the assemblage.
A second region, C, consists of a single station (25) which has a unique
community for this cruise. The densities of Anacystis incerta and
A. thermalis were the lowest at this station at 5 m, while densities of
two diatoms, Cyclotella operculata and C. comta, were highest (Table 6.8).
The community includes Phodomonas minuta var. nannoplanctica, a species
found in the Lake Huron community of October, and Cyclotella michiganiana,
found in the Lake Michigan community for September and October.
Region B is located along the northern coast of the survey area (Fig. 6.37)
and is characterized by a community, Y, of two diatoms: Cyclotella
ocellata and C. stelligera (Fig. 6.36).
109
-------
Figure 6.34. GEOGRAPHIC LOCATIONS OF 5-M SEPTEMBER PHYTOPLANKTON COMMUNITIES. Regions are de-
termined on the basis of the ordination plot of Figure 6.33a. Phytoplankton data are not
available for stations not included in one of the four regions.
-------
Table 6.7. SEPTEMBER PHYTOPLANKTON CELL DENSITIES. Averages (cells/ml) are given over standard error of the mean.
Format same as Table 6.6. Region D Is discussed under "Hypolimnetic associations In September." Last 3 columns
show average densities for epilimnion of northern Lake Michigan (NLM) Stations 52-54 (11 samples). epillmnion of
Stations 20-23 (16 samples), and hypolimnion of Stations 20-23 (14 samples). Stations were sampled on 20-23 Sept.
1973, immediately after sampling of the Straits survey area. See Figure 8.1 for NLM station locations. The
epilimnion is taken to be represented by samples above 20 m and the hypolimnion by those below 30 m.
Gomphosphaeria lacustris*
Anacystis incerta*
Anacystis thermalis*
Oocystis spp . *
Cyclotella michiganiana*
Gloeocystis planctonica
Eutetraoorus species #1
Asteripnella fornosa
Crucigenia guadrata
Cyclotella stelligera*
Fragilaria crotonensis
Tabellaria fenestrata
Synedra filifornds*
Anabaena flos-aquae
Chrysococcus dokidophorus*
Cryptooonas ovata*
Chrysosphaerella longispina
Rhodomonas minuta v. nannoplanctica*
Cyclotella comta*
Cyclotella operculata*
Khizosolenia eriensis*
Cyclotella ocellata*
Region
1
933
99
2951
196
197
23
52
8
73
6
44
9
16
4
24
7
19
9
113
9
84
26
6
2
2.8
.9
37
20
7
2
7
1
0
20
7
27
3
.9
.5
2.1
.8
20
4
label and number of
10
279
34
1629
155
98
16
24
6
55
3
32
9
7
3
9
5
34
12
97
8
81
20
5
2
6
3
10
7
12
3
6
1
0
17
4
24
1
2.3
.7
5
1
58
10
B
7
30
19
200
86
8
6
5
2
15
2
10
4
4
3
14
5
12
7
102
19
61
19
3
1
4
1
0
8
3
6
2
0
17
6
14
3
4
1
11
3
108
24
C
6
231
102
681
238
46
16
31
5
31
5
13
11
9
4
6
4
14
10
75
10
89
22
5
2
2
1
62
58
7
1
6
2
0
27
8
57
6
10
2
14
4
141
38
stations Apparent
D High
4
0 A
84 A
77
5 A
4
7 A
3
10 A
4
4 A
4
0 A
7 A
4
0
92 A,B?
16
73
43
4
2
3
1
0
.5
.5
.5
.5
0
2.6
.5
19 C
3
0 C
26 D,C,B
9
317 D,C,B
84
trend NLM NLM NLM
Low 52-54 20-23 20-23
epi epi hypo
B,D
B,D 2712 2093 49
222 213 22
B,D 218 227 12
28 18 5
B,D
B,D 54 8.5 2.4
4 1.5 .7
D
B,D
C,D 27 2.2 3.9
7 1.5 1.1
D
C? 87 29 26
854
55 10 3.7
14 6 1.2
D
B,D 19 3.4 1.5
3 .9 .5
A,D 1.1 0 0
.4
15 1.2 15
2 .61
111
-------
(a)
RDMINU
CHOOKI
CNOVflT
CYSTEL
(b)
STFILI
Figure 6.35. ORDINATION PLOTS FOR SEPTEMBER SURFACE AND SUBSURFACE SAMPLES. See caption for Figure 6.32
for further information.
(a) Station ordination plot.
(b) Phytoplankton ordination plot.
-------
(a)
(b)
Figure 6.36. AUGUST 5-M WATER SAMPLE ORDINATION PLOTS.
Station locations are given on Figure 6.37.
(a) Station ordination plot.
(b) Phytoplankton ordination plot.
See Figures 6.30 and 6.37 for further discussion.
-------
Table 6.8. AUGUST PHYTOPLANKTON CELL DENSITIES. Average densities (in cells/ml) for each region
(Figs. 6.36 and 6.37) are given over the standard error of the mean. Format is the same as for Table
phytoplankton counts from the 5-m sample at that station. Region D is discussed under "Hypolimnetic
associations in August." Standard errors for region C are based on two replicate counts on one slide.
Taxa identified with an (*) were used in the PCA.
Reuion label and Number
Anacystis incerta*
Anacystis thermalis*
Crucigenia quadrata*
Gloeocystis Dlanctonica*
Oocystis spp.*
Eutetramorus species #1*
Anabaena flos-aquae
Synedra fj.lifortnis
Chrysococcus dokidophorus
Tabellaria fenestrata
Cryptomonas ovata*
Rhizosolenia eriensis
ChrysosphaereJ la longispina
Cyclotella operculata*
Cyclotella comta*
Cyclotella michiganiana*
Rhodomonas minuta v.
nannoplanctica *
Fragilaria crotonensis
Cyclotella stelligera*
Cvclotella ocellata*
Asterionella formosa
AI
5
4348
448
208
25
80
22
165'
29
98
5
308
32
46
38
0
0
0
7
2
0
0
3
1
19
2
20
3
7
1
C7 /
J/ 4
225
87
42
25
4
3
1
3
3
A2
19
3171
231
150
13
55
15
99
17
75
6
204
14
32
17
1.0
.5
0
0
8
1
.8
.4
9
9
3.3
.8
28
2
32
2
3
1
501
79
54
13
28
2
2.5
.5
2
1
BC
11
2363
184
109
13
29
11
70
9
50
3
192
22
38
24
1.0
.4
0
3
2
7
2
1.1
.7
10
10
6.3
.9
46
4
54
4
14
6
535
114
82
18
31
4
3.0
.7
7
4
C
1
2032
453
68
15
17
9
50
25
61
17
230
9
0
0
0
0
11
3
3
1
45
45
6
1
64
9
52
8
10
5
817
84
194
32
83
17
17
6
13
3
of stations
B
3
607
398
29
29
0
90
6
38
13
145
b
0
0
0
0
8
4
0
0
27
6
101
4
61
6
14
2
440
440
90
6
34
8
0
0
DI
3
35
35
0
0
0
3
3
0
0
10
5
13
6
2
1
17
8
0
1
1
17
3
17
2
3
2
28
28
22
22
78
17
48
14
2
2
D2
4
1079
360
54
41
8
8
53
9
25
2
92
30
23
23
4
2
7 .5
7 .5
9
4
7
3
6
4
0
6
2
50
12
47
16
8
2
508
123
163
52
53
9
39
15
8
6
Apparent trend
High Low
A C,D
A C,D
A C,D
A D
A D
A D
A?
D?
D?
D?
C
C A,D
B,C
B,C
B D
B
B,D A
B,D
B
114
-------
- 84-45'-
- 84°30'
Figure 6.37. GEOGRAPHIC LOCATIONS OF 5-M AUGUST PHYTOPLANKTON COMMUNITIES. Regions are deter-
mined on the basis of the ordination plot of Figure 6.36. Stations east of a line from
Station 24 to Station 31 were not sampled.
-------
Hypolimnetic Associations in August
Including seven deep samples with the 5-m samples in the PCA analysis
gave an orientation similar to that for the 5-m samples (Fig. 6.38). The
deep samples added to the analysis are in regions D} and D2, which show
closest proximity to region B and some samples in region BC. This is
evidence that the community in region B is related to the hypolimnetic
community and that region B is upwelled, but also suggests that some
additional stations (11R, 37, 34, 30 and 35) might be upwelled. These
additional stations are located north and east of Bois Blanc Island near
region B (Fig. 6.37).
The hypolimnetic community found at Stations 27, 29 and 35 is character-
ized by two species of Cyclotella, C. ocellata and C. stelligera
(Fig. 6.38). These two taxa also constitute community Z, identified as
the community at region B from the 5-m samples (Fig. 6.36). These con-
clusions that C. ocellata and C. stelligera are favored in region B and
in the hypolimnion is supported by the absolute abundance of these
species (Table 6.8).
Region D2, intermediate between region DI and the surface sample regions
(Fig. 6.38), consists of subsurface samples at stations located for the
most part in the southwestern side of the survey area. For example, the
5-m sample at Station 03 (in the western side of Lake Michigan) belongs
with region A\, which contains community X (green and blue-green algae).
The 25-m sample at the same station, on the basis of Figure 6.38a appears
to have a community intermediate between community X at 5 m and communi-
ty Z of the hypolimnion of the northwestern section. This implies that
deep-water samples do not all have the same phytoplankton community. The
hypolimnion in the northeastern part of the survey area has a phytoplankton
community consisting mainly of Cyclotella ocellata and C. stelligera
(Table 6.8, Figs. 6.38a and b). The hypolimnion of the southwestern side
(identified as having Lake Michigan water at its surface) has a communi-
ty somewhat intermediate between those of surface Lake Michigan and the
hypolimnion of the more northern stations. One possible explanation is
that deep westward currents are carrying the C. ocellata and C. stelligera
(and any other deep-water taxa east of the Straits) into the hypolimnion
of Lake Michigan.
6.5 COMPARISON OF TEMPERATURE-CONDUCTIVITY AND PHYTOPLANKTON COMMUNITY
PATTERNS
If certain phytoplankton communities are associated with specific water
masses, then individual taxa in these water masses should be diluted with
the mixing of water masses. It should, therefore, be possible to deter-
mine how much of the distribution pattern of a given taxa is due to
dilution of water masses and how much is due to other factors.
116
-------
CNOVfCMlflCU
(b)
Figure 6.38. ORDINATION PLOTS FOR AUGUST SURFACE AND SUBSURFACE SAMPLES.
for further information.
(a) Station ordination plot.
(b) Phytoplankton ordination plot.
See caption for Figure 6.32
-------
If a parameter follows water movement and is conservative, then its
value at any surface point x should follow the same rules set forth above
for temperature and conductivity (Sec. IV). If V (x) is the value of
this conservative parameter at x then
V (x) = £ V± F, (x)
1-1
where 7^ (x) is, as before, the fraction of water at x originating from
JL and V.^ is the value of the parameter at source _i. It is shown in
Appendix E that in a system consisting of three water sources it is pos-
sible to express any conservative parameter as a linear combination of
any other two conservative parameters (but only if neither of these two
has equal values at all sources and only if they are linearly independent).
It then follows that:
The value of the conserved parameter V(x) at
surface point x in the Straits survey area
is expressible as a linear combination of
temperature, T(x), and conductivity, C(x),
at that point.
If the density of a phytoplankton taxon is conservative (that is, if it
can be viewed as a passive tracer of water masses and does not grow, die,
sink or get eaten), then it should be possible to obtain a large value
of R2 from a linear regression of the plankton's density against temper-
ature and conductivity. (It should be understood that this regression
is not meant to predict phytoplankton density from temperature and
conductivity in the usual sense, but rather to examine the relationship
of phytoplankton density with water dilution.) The value of R2 is
interpretable as the fraction of variance removed by the regression.
Consequently, the larger R2 is, the better the dilution model explains
the distribution of the plankton. Conversely, a low value of R2 suggests
that water-mass dilution is not the major factor determining the density
estimates of the plankton in the surface samples.
Measurement errors also contribute to the unexplained fraction of the
variance. Since the number of colonies of any one species observed on a
slide did not exceed 50 and was usually very much less than this (Tables
6.9, 6.10), it is apparent that statistical variability in species counts
will be an important contributor to the unexplained variance. Water-mass
dilution accounts for 21 to 74% of the observed densities for the most
abundant taxa, whereas it can account for less than 10% for the least
abundant ones. These results indicate that the values of R2 are at least
partly dependent on counting error, i.e., that the largest values for R2
are associated with the most abundant species.
It is possible to estimate the contribution to the statistical variability
due to the counting procedure. The regression model for R2 may be written
118
-------
Table 6.9. VALUES OF R2 AND RELATED STATISTICS FROM REGRESSIONS OF CELL
DENSITIES AGAINST TEMPERATURE AND CONDUCTIVITY FOR THE MOST ABUNDANT TAXA.
Taxon name
Estimated maximum
number of colonies
observed on a slide
R2 R2
est
R2
est
Standard error
of the angle
(SD)
Anacystis incerta
Anacystis therraalis
Synedra filiformis
Cyclotella michiganiana
Cyclotella stelligera
Cyclotella comta
Chrysococcus dokidophorus
Rfcodomonas minuta v.
nannoplanctica
Cyclotella ocellata
8
n
22
42
29
14
14
16
35
.521
.543
.307
.743
.344
.206
.210
.354
.515
.628
.718
.867
.895
.803
.484
.265
.703
.729
.83
.76
.35
.83
.43
.43
.79
.50
.71
10.3°
10.1
16.7
6.6
13.8
20.7
15.0
14.2
8.3
Table 6.10. VALUES OF R2 FROM REGRESSIONS OF CELL DENSITIES AGAINST TEM-
PERATURE AND CONDUCTIVITY FOR LESS ABUNDANT TAXA.
Taxon name
Estimated maximum
number of colonies
observed on a slide
Standard error
of the angle
(SD)
P.stsrionalla formosa
Oocystis spp.
Gloeocgstis planctonj.es
Ar.a'oaeria flos-aquae
Rhizosolenia eriensis
Sutetramorus species //I
Cyclotella operculata
Ctyptornonas ovata
Chrysosphaerel la longi spina
Fragllaria crotonensis
Tabellaria fenestrata
Crueigrenia quadrata
Gomphasphaeria lacustrJ.s
6
7
2
3
7
2
5
6
5
5
3
4
4
.126
.326
.241
.013
.020
.059
.148
.099
.092
.056
.085
.062
.111
20.2°
15.9
19.5
68.8
55.2
30.9
20.5
31.3
34.3
34.8
26.4
43.3
31.4
119
-------
as:
2 = SST-SSE
SST
N
where SST = total sum of squares = Z
1=1
N 9
SSE = total sum of squares = Z (y^-y^)
1=1
N = number of samples (or stations or slides)
yi = measured value of dependent variable (number of colonies)
for sample 1^
y^ = predicted value of the dependent variable based on the
regression
N
y = average number of colonies per slide = Z y.j
1=1
N
Since we have verified that the colonies are distributed randomly on the
slides, it may be assumed that colony counts follow a Poisson distribu-
tion. Let Ai be the Poisson parameter for the colony counts made of the
species in question over a fixed area A of slide i_. (Ai may be thought
of as the average number of colonies counted in a very large number of
non-overlapping scans each covering an area A of this slide.) From the
properties of the Poisson distribution, Ai equals the variance and the
mean. Each slide count is a sample of size one from a Poisson distribu-
tion with parameter Ai, and thus Ai may be estimated as either:
Ai = y±
or
Ai = MSB = (3
Consequently:
N
SSE = Z (y_.
1=1 3
N
= Z Ai
1=1
N
~ V "\7
- L yi
1=1
120
-------
This permits an estimate for R2 which is based on the number of colonies
counted on a slide:
2 _ SST-SSEes<-
est ~ SST
N
where SSEest = I, yi
i=l
The R2est can be calculated before the regression is performed and pro-
vides a means of evaluating the R2 resulting from the regression analysis.
If R2 nearly equals R2est» it ™ay be concluded that the fraction of the
variance not explained by the regression can be accounted for mainly by
counting error.
The ratio of R2/R2est may be interpreted as the fraction of the variance
of cell density accounted for by dilution. The unexplained fraction
includes contributions due to sample preparation (believed to be much
smaller than the contribution due to counting, which was considered above
and is included in R2est) and other factors including patchiness, growth,
death, sinking, and predation. Very large fractions (over 70%) of the
variance of the densities for Anacystis incerta, Anacystis thermalis,
Cyclotella michiganiana, Chrysococcus dokidophorus, and Cyclotella
ocellata are apparently explained by water mixing, whereas other taxa have
between 35% and 50% of the variance explained by dilution (Table 6.9).
The species with the lowest fraction explainable by dilution is Synedra
filifornds. The unaccounted fraction is almost entirely the result of
the extremely high density at Station 06. For the other taxa, the dif-
ference between R2 and R2est is not explained as simply.
An examination of the residuals of the regression might help identify
additional factors determining cell density. If, for example, the resid-
uals (residual is defined as the value predicted on the basis of the
regression minus the measured value: [y^-y^]) for a species most abundant
in Lake Michigan increase toward the southeast, then this species is
probably sinking or being preyed upon faster than it is reproducing as
water moves from Lake Michigan to Lake Huron. Another explanation might
be that cell densities at the source are increasing but that net produc-
tion is not equal to the rate of dilution with Lake Huron or St. Marys
River water. Examination of residuals of these species (Table 6.9),
however, do not show any simple patterns. Instead, the factors affecting
the residuals appear for the most part to be local and erratic. For
example, the extremely high cell density of Synedra filiformis at
Station 06 is inconsistent with the dilution patterns as defined by^tem-
perature and conductivity. Cyclotella stelligera attains high densities
at Stations 04 and 05 as well as at 06. The densities of C. stelligera
between Stations 02 and 06 are not consistent with dilution patterns. The
very high density at Station 42 is also highly inconsistent with dilution
patterns.
121
-------
The general conclusion to be drawn from the analysis of phytoplankton
densities relative to the water-mass dilution is that, for most species,
simple dilution seems to be a very important factor determining distribu-
tion patterns and that for some it may be the only significant factor.
Most phytoplankton species therefore appear to be semi-conservative in
the sense that at least half of the density variance is explainable by
water dilution.
The regressions of plankton densities vs. temperature and conductivity
can also be used to indicate diagrammatically where the plankton are
found (Fig. 6.39). Multiple linear regression with two independent vari-
ables is usually viewed as a technique of finding the least squares plane
passing through points in three-dimensional space. It can also be viewed,
however, as a two-dimensional problem. The regression of cell density D
on temperature and conductivity determines statistical parameters a, 3
and y for the regression model
D± = 3T± + yCi + a + ei
where D-^ = density at station i^
T£ = temperature at station i^
C^ = conductivity at station i^
e^ = error
such that the canonical variable (3T + yC + a) maximally correlates with
D. In this sense it is very similar to canonical correlation. If the
regression coefficients 3 and y are normalized:
3 Y
g' = /gz + Yz and y' = /3Z + yz
then g' and y' may be interpreted as direction cosine for the axis of
the canonical variable (3T + yC + a) in the T-C plane.
It is also possible to estimate the angular error associated with the
direction of each arrow. Using a Taylor expansion, it is possible to
show that (derivation is omitted) :
SD2 = Var[arctan(y/x) ] &
(n-3)2 [xy(Varx-Vary)+(y2-x2)Covxy]2 + (n-3) (y2Varx-xyCovxy+x2Vary)
n(n-l) (x2+y2) * (n-1) (x2+y2) 2
Here, y is the regression coefficient associated with conductivity and x
is the regression coefficient associated with temperature. Simulations
to test the accuracy of this approximation show that, for n > 30, it is
accurate to about 2% for SD in the range 2° to 10° and accurate to about
15% for SD in the range 50° to 70°. The approximation shows a tendency
to underestimate that is especially noticeable when SD is greater than
122
-------
260
240
220
200
H
>
P
O
3
160
160
140
120
LAKE
HURON
A Oocystlj app.
B Gloeocystls plonetonlca
C Anabatna floe-aquae
D Rhizoeolenia erlensfe
E Euletramorus species rt I
P Cyclotella operculata
8 Cryptomonas ovota
H Chrysosphaerella longlsplno
I Frogilorio crotonenais
J Tabellaria fenestrata
K Crucigenla quadrota
L Qomphoephoeria lacustris
\
ST. MARYS
RIVER
H
12 13
TEMPERATURE °C
14
Figure 6.39. PHYTOPLANKTON TRENDS ON THE T-C PLANE. Numbers refer to sta-
tions and are plotted in the T-C plane. Only 5-m samples are considered,
and only stations for which phytoplankton data exist are shown. Each
arrow shows the direction in the T-C plane in which the corresponding
phytoplankton taxon tends to be most abundant; length of arrow indicates
strength of tendency. Directions for arrows are taken from multiple
linear regressions of cell density against temperature and conductivity;
length of arrow represents value of R2 for that regression. Arcs at ar-
row tips represent standard error of the angle as estimated from the
variance-covariance matrix of the regression coefficients. Dashed line
indicates value of R2est-
123
-------
30°. As might be expected, SD increases as R2 and the number of colonies
counted decreases (Tables 6.9, 6.10). The values of SD shown are, for
the most part, relatively small and indicate that the directions on the
arrows shown in Figure 6.39 are reasonably accurate..
The plot in Figure 6.39 may be seen as an ordination of stations and
phytoplankton, but of a different nature than the ones shown in
Figure 6.30 where each station and phytoplankton taxon is ordinated rela-
tive to the phytoplankton community. In Figure 6.39 the relationships
of both stations and phytoplankton are shown relative to water-mass dilu-
tion as revealed by temperature and conductivity. Figure 6.30 displays
results of a single multivariate ordination; the use of the term
"multivariate" means that the ordination examines community relationships.
In Figure 6.39, the results of univariate analyses for temperature and
specific conductance and 22 phytoplankton taxa are shown. If Figure 6.39
is rotated 45° clockwise relative to Figure 6.30, rather striking simi-
larities are revealed between station locations as well as taxa locations.
This again supports the conclusion that the distribution of communities
illustrated in Figure 6.31 is due mainly to the dilution of the individual
taxa found in the communities of Lake Michigan, Lake Huron and the
St. Marys River.
The direction of an arrow in Figure 6.39 indicates direction of highest
occurrences, and the length of the arrow the strength of the trend. The
arrow for Cyclotella wichiganiana, for example, points in the direction
of the Lake Michigan stations. It therefore appears to show a tendency
toward high densities in Lake Michigan and low densities in Lake Huron
and the St. Marys River. The length of the arrow or the R2 indicates
that this tendency is very strong. Arrows for Anacystis incerta and
A. thermalis are shifted more toward the Lake Huron stations than the
arrow for C. michiganiana. It would be concluded that these species,
though most abundant in Lake Michigan, are more abundant at Lake Huron
stations than at stations of the St. Marys River. The arrow of
Cyclotella stelligera points almost straight up. It is abundant both at
Lake Huron and Lake Michigan stations but relatively rare at the
St. Marys River. Cyclotella ocellata is most abundant toward Lake Huron
stations, whereas Rhodomonas minuta var. nannoplanctica, though very
abundant at Lake Huron stations, is more abundant at St. Marys River than
in Lake Michigan since its arrow points generally toward Lake Huron
stations but also somewhat toward St. Marys River stations and away from
Lake Michigan stations. Only three species, Asterionella fornosa,
Tabellaria fenestrata, and Fragilaria crotonensis, appear to be most
abundant at the St. Marys River—all have relatively small values of R2.
It is apparent that most arrows in Figure 6.39 tend to be oriented toward
Lake Michigan, Lake Huron or the St. Marys River, implying that most of
the 22 taxa are abundant in only one of the three water types. Few taxa
appear to be equally abundant in two water types simultaneously. A taxon
occurring equally at all three water types would have a nondirected
arrow—that is one of very short length.
124
-------
The actual cell densities of Cyclotella ndchiganiana, C. ocellata, and
C. stelligera at stations in the survey area are shown in Figures'e.40,
6.41 and 6.42, and can be compared with the results shown in Figure 6.39.
Cyclotella michiganiana is most abundant at Lake Michigan stations and
becomes less abundant as Lake Michigan water dilutes with Lake Huron or
St. Marys River water (Fig. 6.40). Highest densities of C. ocellata are
toward Lake Huron and lower densities toward Lake Michigan and the
St. Marys River (Fig. 6.41). These conclusions are consistent with the
results shown in Figure 6.39 and Table 6.2.
As suggested by Figure 6.39, C. stelligera appears to be most abundant
in Lakes Michigan and Huron, although it is also found at the St. Marys
River. Its densities, however, are low at stations in the center of
Figure 6.42, being higher at the sources than at stations where the
waters from these sources mix. This pattern is quite inconsistent with
the dilution model which results in the large difference between R2 and
R2est given in Table 6.9, and was not evident in the distribution of any
other taxa, although it is possible that counting the algae samples more
fully would uncover such patterns for other phytoplankton. One possible
cause for the odd distribution of C. stelligera would be the occurrence
of very rapidly developing blooms simultaneously at each of the sources
(but not in the mixed water) immediately before or during the time the
samples were collected.
Distribution of Chemical-Physical Parameters at 5 m During October
Regressions of several physical-chemical parameters and rates of phyto-
plankton carbon fixation vs. temperature and specific conductance were
calculated for the data from 5 m in October. Results are listed in
Table 6.11 and plotted in Figure 6.43.
The R2 for chloride is nearly 1.0, indicating chloride behaves as a
conservative parameter (Table 6.11). Since the arrow for chloride is
parallel to the conductivity axis, it appears that conductivity and
chloride analyses measure the same thing in these samples or are, at
least, redundant. That the R2 value is not 1.0 may be explained by
measurement errors. Since the arrow for chloride points away from the
vertex for the St. Marys River, chloride values are very low there rela-
tive to the other sources. Chloride is higher in Lake Michigan than in
Lake Huron, since the arrow points more nearly in the direction of the
Lake Michigan source.
Alkalinity, surprisingly, based on the R2 from the regression, acts as
a nearly conserved property (Table 6.11). The changes induced by the
biota through photosynthesis and respiration may be too slow relative to
the transit time of the water through the survey area to affect the
results attributed to dilution. Alkalinity is very large in Lake Michigan
compared to values in the St. Marys River, which also may account for the
apparent conservative behavior.
125
-------
260r
320
200
•rs"®/
/"V-" \_A_J V-X'ii'h/ml/
LAKE MICHIGAN
?
o
LAK£ HURON--
JiK£ HUF
O
CD
O
O
X o
©
o
120
sO
\
\
\
o
\
CYCLOTELLR MICHIGRNIflNfl CELLS/HL
X I
ST. MARYS
RIVER
12 13
TEMPERATURE *C
Figure 6.40. CELL DENSITIES FOR CYCLOTELLA MICHIGANIANA ON
THE T-C PLANE FOR OCTOBER. Each 5-m sample is located on
the T-C plane. At the location of the sample in this
plane, a circle is drawn which has an area proportional to
the cell density. These plots may be used to help inter-
pret Figure 6.39. Use Figure 6.39 as a key to determine
with which station a circle corresponds.
The pH data are not, strictly speaking, conserved mainly due to strong
buffering capacity of the Great Lakes and to the fact that pH relation-
ships are not linear, i.e., pH is not conserved because it does not follow
the definition of equation 1 of Section IV. Nonetheless, pH shows a
surprisingly high value of R2. Its distribution is virtually identical
with that of alkalinity but is less nearly conservative.
Sulfate is generally considered to be a conservative parameter. Its
relatively low value of R2 may be explained by the analytical technique
which, at the time of this project, was still being developed at this
laboratory (Santiago et al. 1975). Sulfate concentrations are largest in
Lake Michigan.
Nitrate nitrogen has a surprisingly high R2 for a nutrient required by
phytoplankton. Since it is not limiting in the upper Great Lakes
126
-------
260 r
240
220
200
180
140 -
120-
-"
-oo "6 /
CYCLOTELLR OCELLHTfi CELLS/ML
12 13
TEMPERATURE °C
Figure 6.41. CELL DENSITIES FOR CYCLOTELLA OCELLATA. See
caption for Figure "6.40.
(Schelske 1975) and is found in relatively high concentrations, apparently
it is changed slowly by the biota and acts like a nearly conservative
parameter. Nitrate was highest at the St. Marys River and very low in
Lake Michigan.
Rates of carbon fixation, soluble reactive silica and total phosphorus
were not conservative, as expected and shown by the relatively low R2
(Table 6.11). Carbon fixation was about equal in Lake Huron and the
St. Marys River but was larger in Lake Michigan. Silica is limiting for
diatoms in the Great Lakes (Schelske 1975), and its small value for R2
indicates silica concentration was not conservative. Silica concentra-
tions were much larger in the St. Marys River than in Lake Michigan or
Lake Huron. R2 for total phosphorus and soluble phosphorus was very low,
indicating that dilution was not a large factor relative to explaining
concentrations in the study area.
The relatively large variance in total phosphorus results (Table 3.1)
suggests that analytical or sampling methods are not precise. The vari-
ance is large not only relative to the mean but also to the range of
127
-------
260
340
220
o ISO
160
-GOO-'87
V_A_X x—' a
LAKC MICHIMH
IJ6 I
cells/ml'
o
^ o
GD°
o
Oo|
\
O
\
O
\
\
CYCLOTELLfl STELLIGERfl CELLS/ML
T. MARYS
RIVER
12 13
TEMPERATURE °C
Figure 6.42. CELL DENSITIES FOR CYCLOTELLA STELLIGERA. See
caption for Figure 6.40.
averages for different groups of stations. If it were not for the prob-
lem of variable results with phosphorus, one would have to conclude that
biological and other environmental processes, not dilution, control the
concentrations of silica and phosphorus. Nitrate is probably an excep-
tion due to the fact that it is not limiting, that the soluble component
is measured (instead of the particulate and soluble in the case of total
phosphorus) and that the concentration difference is large between Lake
Michigan and the St. Marys River.
Although the Secchi depth transparency is not conserved (i.e. does not
obey eq. 1 of Sec. IV), its reciprocal, which may be associated with
extinction coefficient (e.g. Ladewski and Stoermer 1973), can be taken
as an estimate of suspended particulate material, which may in turn be
conserved if biological activity and sinking can be neglected. The
reciprocal Secchi depth is highest at the St. Marys River where the water
is quite turbid, due probably to inorganic materials, and lowest in Lake
Huron where the water is relatively clear. The moderate value of R2
suggests that particulate loading might be semi-conservative if measured
with a more accurate instrument.
128
-------
260
240
220-
o 200-
•x
o
180-
U
§
8 '60-
140-
120
LAKE
MICHIGAN
/ ST. MARYS
u RIVER
12 13
TEMPERATURE °C
Figure 6.43. TRENDS OF PHYSICAL AND CHEMICAL PARAMETERS IN THE T-C
PLANE. Concept and format same as Figure 6.39.
129
-------
Table 6.11. VALUES OF R2 AND SD FROM REGRESSIONS OF PHYSICAL-
CHEMICAL PARAMETERS AGAINST TEMPERATURE AND CONDUCTIVITY.
Parameter
Cl
Alkalinity
PH
SO^
Carbon fixation
Total soluble POi,
Total P04
Secchi""*
Si02
NO 3
R2
.933
.868
.609
.433
.247
.135
.179
.494
.363
.836
Standard deviation
(SD) of the angle
in degrees
2.3
3.7
7.5
11.8
19-3
24.4
15.4
6.3
8.9
4.8
6.6 LITERATURE CITED
Cooley, W. W. and P. R. Lohnes. 1971. Multivariate data analysis.
New York: John Wiley & Sons, Inc. 364 p.
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. Board Canada 31:
731-738.
Drouet, F. and W. A. Daily. 1956. Revision of the Coccoid Myxophyceae.
Butler Univ. Botanical Studies, Vol. 12. 218 p.
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. Survey, N.S., Vol. 3, No 1
211 p.
Huber-Pestalozzi, G. 1942. Das Phytoplankton des Susswassers. Die
Binnengewasser 16, Teil 2, 2. Halfte, Diatomeen. Stuttgart. 549 p.
130
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Hustedt, F.( 1930. Bacillariophyta (Diatomeae). m A. Pascher (ed.)
Die Susswasser-Flora Mitteleuropas. Heft 10. Jena: Gustav Fischer
Verlag. 466 p.
Hutchinson, G. E. 1967. A treatise on limnology. II. Introduction to
lake biology and the limnop lank ton. New York: Wiley. 1115 p.
Koppen, J. D. 1975. A morphological and taxonomic consideration of
Tabellaria (Bacillariophyceae) from the northcentral United States
J. Phycol. 11: 236-244.
Ladewski, T. B. and E. F. Stoermer. 1973. Water transparency in southern
Lake Michigan in 1971 and 1972. Proc. 16th Conf. Great Lakes Res.:
791-807, Internat. Assoc. Great Lakes Res.
Morrison, D. 1967. Multivariate statistical methods. New York: McGraw-
Hill. 338 p.
Munawar, M. and A. Nauwerck. 1971. The composition and horizontal
distribution of phytoplankton in Lake Ontario during the year 1970.
Proc. 14th Conf. Great Lakes Res.: 69-78, Internat. Assoc. Great
Lakes Res.
Orloci, L. 1966. Geometric models in ecology. I. The theory and appli-
cation of some ordination methods. J. Ecol. 54: 193-215.
Santiago, M. A., Saundra Fielek and C. L. Schelske. 1975. Automated
method for sulfate determination in lake water. Water Quality
Parameters, ASTM STP 573: 35-46. Amer. Soc. for Testing and
Materials.
Schelske, C. L. 1975. Silica and nitrate depletion as related to rate
of eutrophication in Lakes Michigan, Huron and Superior, p. 277-298.
In A. D. Hasler (ed.), Coupling of land and water systems. New York:
Springer-Verlag New York Inc.
, L. E. Feldt, M. A. Santiago and E. F. Stoermer. 1972.
Nutrient enrichment and its effect on phytoplankton production and
species composition in Lake Superior. Proc. 15th Conf. Great Lakes
Res.: 149-165, Internat. Assoc. Great Lakes Res.
, , M. S. Simmons and . 1974. Storm
induced relationships among chemical conditions and phytoplankton in
Saginaw Bay and western Lake Huron. Proc. 17th Conf. Great Lakes
Res.: 78-91, Internat. Assoc. Great Lakes Res.
and J. C. Roth. 1973. Limnological survey of Lakes Michigan,
Superior, Huron and Erie. Univ. Mich., Great Lakes Res. Div.
Pub. 17. 108 p.
131
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and E. F. Stoermer. 1971. Eutrophication, silica depletion
and predicted changes in algal quality in Lake Michigan.
Science 173: 423-424.
and . 1972. Phosphorus, silica and eutrophication
of Lake Michigan, p. 157-171. In G. E. Likens (ed.), Nutrients and
eutrophication. Amer. Soc. Limnol. Oceanogr., Spec. Symp. 1.
Stoermer, E. F. 1972. Statement, p. 217-254. In Conf. Pollution of
Lake Michigan and its tributary basin, Illinois, Indiana, Michigan,
and Wisconsin - 4th session, Sept. 19-21, 1972, Chicago, 111. U.S.
Environmental Protection Agency. Vol. I.
, M. M. Bowman, J. C. Kingston and A. L. Schaedel. 1974.
Phytoplankton composition and abundance during IFYGL. Univ. Mich.,
Great Lakes Res. Div., Spec. Rep. No. 53. 373 p.
, C. L. Schelske, M. A. Santiago and L. E. Feldt. 1972.
Spring phytoplankton abundance and productivity in Grand Traverse
Bay, Lake Michigan, 1970. Proc. 15th Conf. Great Lakes Res.:
181-191, Internat. Assoc. Great Lakes Res.
and J. J. Yang. 1969. Plankton diatom assemblages in Lake
Michigan. Univ. Mich., Great Lakes Res. Div., Spec. Rep. 47.
268 p.
and . 1970. Distribution and relative abundance
of dominant plankton diatoms in Lake Michigan. Univ. Mich., Great
Lakes Res. Div. Pub. 16. 64 p.
Strong, A. E., H. G. Stumpf, J. L. Hart and J. A. Pritchard. 1974.
Extensive summer upwelling on Lake Michigan during 1973 observed by
NOAA-2 and ERTS-1 satellites. Proc. 9th Internat. Symp. Remote
Sensing of Environment, 15-19 April 1974. Environmental Res. Inst.
of Mich., Ann Arbor, p. 923-932.
Vollenweider, R. A., M. Munawar and P. Stadelmann. 1974. A comparative
review of phytoplankton and primary production in the Laurentian
Great Lakes. J. Fish. Res. Board Canada 31: 739-762.
132
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SECTION VII
CRUSTACEAN ZOOPLANKTON OF THE STRAITS OF MACKINAC AND
NORTHERN LAKE MICHIGAN
by
John E. Gannon, Kathryn S. Bricker and Theodore B. Ladewski
7.1 INTRODUCTION
Zooplankton samples were first procured from the Laurentian Great Lakes
nearly 100 years ago. However, due to the difficulty and high cost of
sampling such large water bodies, our knowledge of zooplankton ecology
in the Great Lakes has accrued slowly. Relatively few studies have been
conducted, and knowledge of zooplankton has barely advanced beyond de-
scriptive ecology (Gannon 1969) . Our current understanding of zooplankton
species composition, abundance, and distribution in the open waters of
the Great Lakes is fairly complete and has recently been reviewed by
Davis (1966), Patalas (1972), and Watson and Carpenter (1974). However,
many ecologically and economically strategic regions such as embayments,
inshore areas, and interconnecting waterways remain to be investigated.
One of these important areas is the Straits of Mackinac, the zone of
water exchange between Lakes Michigan and Huron.
As part of a physicochemical and biological investigation of this limno-
logically dynamic region, we studied crustacean zooplankton in the
Straits of Mackinac during 1973. Since this was the first investigation
of zooplankton in tliis region, our primary objective was to provide
benchmark data on species composition, distribution, and abundance. Our
second objective was to analyze zooplankton community structure in rela-
tion to the interactions of Lake Michigan and Lake Huron waters. A
third objective was to provide information on crustacean zooplankton in
northern Lake Michigan, as most prior zooplankton investigations in Lake
Michigan have focused only on the southern third of the lake (Gannon
1974a). These data are included primarily to contrast and compare zoo-
plankton community structure between northern Lake Michigan and the
Straits of Mackinac.
7.2 METHODS AND MATERIALS
Field
Samples were obtained with a 0.5-m diameter cylinder-cone net towed
133
-------
vertically from near bottom to the surface at approximately 0.5 m/sec.
The net material consisted of nylon monofilament screen cloth of 250 p
mesh apertures with a porosity of 44%. This mesh size closely corre-
sponds to the No. 6 mesh (239 y) of the old silk bolting cloth rating
system (Welch 1948). Since the net was 2 m long, vertical tows were from
2 m off bottom to the surface. Extra care was taken to insure that the
cod end of the net hit bottom before beginning the vertical ascent.
Single samples were procured at most stations. However, several stations
were sampled twice during a cruise in order to investigate variations in
species composition and abundance over a short time span.
The tow net was fitted with a Nansen throttling mechanism and split tows
were obtained at deep stations where a distinct thermocline was present.
Two vertical tows, one from the bottom to the top of the hypolimnion and
the other from the bottom of the thermocline to the surface, were made
at approximately one-third of the stations during each cruise. The
Nansen closing net was employed primarily to reduce effects of net clog-
ging during long vertical tows.
Another plankton tow from near bottom to the surface was made at each
station using a 0.5-m diameter No. 20 (76 y mesh size) conical net. This
net was employed to qualitatively collect smaller plankters such as roti-
fers. These samples have not been analyzed to date.
In order to aid in the interpretation of zooplankton data in the Straits
region, samples were also taken in northern Lake Michigan at 18 stations
during 20-23 September 1973 (Fig. 7.1). Vertical tows from near bottom
to the surface were obtained with both the No. 6 and No. 20 mesh nets.
Upon completion of each vertical haul, the net was washed thoroughly and
the contents of the cod end bucket were carefully transferred to an 8-oz
screw cap jar. Carbonated water (club soda) was immediately added as a
narcotizing agent (Gannon and Gannon 1975). After approximately 5 min,
most locomotor activity had ceased, and the sample was preserved in 5%
buffered formalin.
The mesh size used in any study should be sufficiently small to capture
the desired organisms but large enough to avoid clogging by phytoplankton.
The mesh size of 250 p was chosen for its good filtration characteristics
and to catch all adult crustacean zooplankters. Net filtration efficiency
tests were not conducted in the Straits region. However, such tests were
made using flowmeters in the offshore waters of Lake Michigan where fil-
tration efficiency ranged from 86.7-99.7% (Gannon 1972a). In order to
test the efficiency of the net to capture crustacean zooplankton, compari-
sons of the catch of the net and a 7-liter capacity transparent Van Dorn
bottle were made at a station in Lake Huron near the mouth of Saginaw Bay
on 15 August 1974. Quantitative analyses of these samples revealed that
numbers of the smallest zooplankters (Chydorus sphaericus, Bosmina
longirostris, Eubosmina coregoni, Ceriodaphnia lacustris, C. guadrangula,
Tropocyclops prasinus mexicanus, and cyclopoid copepodids) were relatively
lower in the net tow than in the water bottle. Consequently, these
species appear to be somewhat under-sampled by the No. 6 mesh net.
134
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STRAITS OF
L MACKINAC
BEAVER 0
ISLAND
X 2T X 20
AREA
^ENLARGED
46 X
-aX v X 47
28 45
NORTHERN LAKE
MICHIGAN
Ml.
0 10 20 30 40 50
Figure 7.1. LOCATION OF ZOOPLANKTON SAMPLING STATIONS
IN NORTHERN LAKE MICHIGAN, SEPTEMBER 1973.
A test was conducted on 25 July 1974 at a 27-m deep station in the
Straits of Mackinac to compare the efficiency of the Nansen closing net
in capturing crustacean zooplankton. A vertical tow was made from near
bottom to surface and then two tows, one in the hypolimnion and the
other in the thermocline and epilimnion, were conducted using the Nansen
closing mechanism. Numbers of Crustacea were somewhat higher in the
split tows than in the tow of the entire water column. Consequently some
clogging in long tows through the entire water column is suspected.
Species composition and abundance of zooplankton were similar at those
stations sampled twice within a few hours. In those instances where a
station sampling was repeated after many hours, zooplankton abundance
varied considerably. However, even though abundance was decidely dif-
ferent, percent composition of species remained closely similar. For
135
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example, Station 24 was sampled on 7 and 8 October 1973. The abundance
of calanoid copepods was 3,086 individuals/m3 on the first day and
7,533/m3 on the second, but percent composition increased only from 64.1
to 69.4%. Consequently, interpretation of data based upon percent compo-
sition rather than abundances may be more valid.
Laboratory
All adult crustacean zooplankton were identified to species. Copepodids
were identified to species except those of Diaptomus and Cyclops, which
were identified to genus only. Identifications were made according to
Yeatman (1959) for cyclopoid copepods, Wilson (1959) for calanoid cope-
pods, Brooks (1957) for Daphnia, Deevey and Deevey (1971) for Eubosmina,
and Brooks (1959) for remaining Cladocera.
Each sample was adjusted to a standard volume in a graduated cylinder.
The sample was mixed thoroughly by random movements of a Hensen-Stemp el
pipette; then a subsample was quickly drawn from the middle of the
cylinder with the pipette. Aliquots of 0.5, 1.0, or 5.0 ml were obtained
with properly calibrated pipettes depending upon concentration of organ-
isms. The subsample was transferred to a chambered counting cell
(Gannon 1971). The entire contents of the cell, usually 150-300 individ-
uals, were enumerated at 30-60 X under a Bausch and Lomb stereozoom
microscope. Those organisms requiring higher magnification for identifi-
cation were transferred to an American Optical compound microscope and
observed at 100 or 430 X. Two subsamples were counted from each sample
and the results averaged. If the counts varied more than 30%, a third
subsample was enumerated and only the two counts in closest agreement
were retained. Data were calculated in numbers of individuals per m3
assuming 100% filtration efficiency. These data appear in Appendix F.1-.3
for the Straits of Mackinac and Appendix F.4 for northern Lake Michigan.
Percent relative abundance was also calculated for each species.
The subsampling and counting procedure was tested for accuracy and repro-
ducibility. Errors in the procedure were random, indicating that the meth-
ods employed were reliable (Gannon 1972a). Further statistical tests using
least squares regression analysis were performed on the subsampling and
counting procedure. It was found that when an error estimate of 25% at the
95% confidence level is desired, a minimum of 12 individuals per species
must be counted. Numerical estimates of those rarer species in which there
were less than 12 individuals per subsample, i.e., roughly less than 150
individuals/m3, were considered as statistically unreliable.
Analytical
Principal component analysis (PCA) as described in Section 6.1 was used
as the analytical technique. Three criteria were used to select the taxa
for the principal component analysis (PCA) of a particular month. First,
it was required that each taxon be well enough defined taxonomically that
its contribution to the results of the analysis is interpretable. With
136
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the exception of Diaptomus spp. copepodids, composite categories were
avoided. Diaptomus spp. copepodite stages are believed to have similar
ecological requirements and thus were expected to show interpretable
distributional patterns relative to the other taxa. The second criterion
was that each taxon must be observed at more than 30% of the stations of
the particular cruise in question. Taxa which are not widely distributed
tend to dominate PCA by making the few stations at which they do occur
look particularly unusual. This is a problem common among parametric
multivariate techniques, which in general perform poorly on data which
are badly skewed or include a large number of tied cases. The non-inclu-
sion of locally distributed taxa is further justified on the basis that
the distributions of such taxa are generally easy to describe without the
use of multivariate analysis. The choice of 30% as a cutoff point is
based largely on past experience with PCA and represents the compromise
of including as many taxa as possible without including ones which are
locally or erratically distributed. The third criterion for inclusion
of a taxa was that it be counted with reasonable accuracy. It was conse-
quently required that each taxon exceed 10 individuals in at least one
sample. This criterion was never directly imposed, however, because all
taxa which satisfied the second criterion also easily satisfied this
third one.
Using these criteria, 19 taxa were chosen for analysis of the August data
and 17 for the September and October data. Initial principal component
analyses were performed on each month's data. One rare species,
Diaphanosoma leuchtenbergianum, which was included in the original analy-
ses of each cruise, showed no distributional patterns consistent with
the regions determined by the PCAs. Consequently it was decided not to
include this species in the final analyses but instead to discuss its
distribution independently.
Separate PCAs were performed for each cruise, using the correlation matrix
of the percent composition of the selected taxa. The percent composition,
Pij, for taxon ± at station j_ was computed as: P-H = (NIJ/NXJ) x 100%,
where N^ is the number of individuals of taxon i_ found at station j_ and
and NTJ is the total zooplankton count at station j_. Station 40 was not
used in determining the principal components for the October data since
the zooplankton community at that station was particularly unusual and
did not correspond with the community of any other station in the survey
area. The cumulative percentages of the total variance contributed by
each of the first four principal components for the analyses are:
Cruise Number of
number stations PCI. PC2 PCS PC4
1 (August) 37 35% 46% 55% 63%
2 (September) 40 42 52 62 71
3 (October) 49 26 43 55 63
137
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Plots were drawn showing the location of each of the stations relative to
the first two PCs. The stations belonging to different regions on these
PCA plots are identified on maps of the survey area, and simple averages
for each taxon in each region are tabulated to determine the distribution
pattern of each taxon relative to those regions. We consider the maps
and tables of averages and not the original PC plots to be of most impor-
tance. The choice of Euclidean distance as a measure of similarity
(rather than, for example, coefficient of community or percent similarity)
and the decision not to use a non-linear data transformation (for example,
arcsine /P-H ) were made for this reason.
For each cruise, the first PC was interpretable as a Lake Michigan-Lake
Huron axis. Consequently, the largest share of the variance in the data
may be interpreted as being due to an east-west or Lake Michigan-Lake
Huron effect. The first PC of Cruise 2 by itself accounted for a large
percentage of the total variance. Third and higher PCs were not used in
interpreting any of the analyses.
7.3 RESULTS AND DISCUSSION
Straits of Mackinac
Twenty-nine taxa of crustacean zooplankton were recorded in the Straits
region (Table 7.1). Twenty-three species of Cladocera and Copepoda were
characteristic of limnetic waters, while six cladocerans were considered
as benthic and littoral forms that sporadically appeared in the plankton.
Seven calanoid and three cyclopoid copepods were represented. Diaptomis
oregonensis, D. minutus, and Epischura lacustris were the numerically
predominant calanoid copepods. Cyclops bicuspidatus thomasi was by far
the most abundant cyclopoid copepod. Cladocera were represented by 13
limnetic and six littoral and benthic species. Daphnia galeata mendotae,
D. retrocurva, Holopedium gibberum and Eubosndna coregoni were the pre-
dominant limnetic cladocerans. Ceriodaphnia reticulata was represented
only by a single individual at Station 20 during Cruise 1. Single
specimens of Drepanothrix dentata were observed at Station 23 during
Cruise 2 and Station 03 during Cruise 3. These two species are apparently
new records for Lakes Michigan and Huron.
The opposum shrimp, Afysis relicta Loven, and the deepwater amphipod,
Pontoporeia affinis Lindstrom, were occasionally collected in plankton
samples. Afysis was observed at Stations 08, 44, and 50 on Cruise 2 and
at Station 47 on Cruise 3. Pontoporeia was observed at Station 35 during
Cruise 3. Since these organisms are predominantly benthic during the
daytime, they were undoubtedly inadequately sampled by the plankton net
and these data by no means reflect their abundance or distribution in the
Straits region.
138
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Table 7.1. LIST OF CRUSTACEAN ZOOPLANKTON SPECIES COL-
LECTED IN THE STRAITS OF MACKINAC REGION DURING 1973.
The symbol (*) denotes those species that are predomi-
nantly benthic and appear adventitiously in the plankton,
Calanoid Copepoda
Diaptomus ashlandi Marsh
Diaptomus minutus Lilljeborg
Diaptomus oregonensis Lilljeborg
Diaptomus sicilis Lilljeborg
Epischura lacustris Forbes
Limnocalanus macrurus Sars
Senecella calanoides Juday
Cyclopoid Copepoda
Cyclops bicuspidatus thomasi Forbes
Mesocyclops edax Forbes
Tropocyclops prasinus mexicanus Kiefer
Cladocera
Family Leptodoridae
Leptodora kindtii (Focke)
Family Polyphemidae
Polyphemus pediculus (L.)
Family Sididae
Diaphanosoma leuchtenbergianum Fischer
*Sida crystal!ina (Muller)
Family Holopedidae
Holopedium gibberum Zaddach
Family Daphnidae
Ceriodaphnia lacustris Birge
Ceriodaphnia quadrangula Muller
Ceriodaphnia reticulata (Jurine)
Daphnia galeata mendotae Birge
Daphnia longiremis Sars
Daphnia retrocurva Forbes
Family Bosminidae
Bosmina longirostris (Muller)
Eubosmina coregoni (Baird)
Family Chydoridae
*Acroperus harpae Baird
*Alona affinis (Leydig) f|
*Alona guadrangularis (Muller)
Chydorus sphaericus Muller
*Drepanothrix dentata (Euren)
*Eurycercus lamellatus (Muller)
139
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Abundance of total Crustacea at various stations ranged from nearly
1,000 individuals/m3 to almost 28,000/m3 during the study period
(Fig. 7.2). Average standing crops for Cruises 1, 2, and 3 were 8,642,
5,014, and 11,975/m3, respectively. Higher numbers in October mainly
reflect recruitment of young instars, especially of Diaptomus spp., into
the population. Concentrations of organisms were often higher at inshore
stations and near Bois Blanc and Mackinac Islands.
Calanoid copepods were an important fraction of the plankton in the
Straits region. They increased from an average of 3,862/m3 (42% of total
Crustacea) in August to 6,417/m3 (57% of total Crustacea) in October
(Fig. 7.3). A pronounced east-west difference in abundance of calanoid
copepods was observed during August and September. Numbers of calanoid
copepods were approximately 2-10 times lower west of the Mackinac Bridge
and in the South Channel (south of Bois Blanc Island) than towards the
Lake Huron portion of the Straits. This pattern was less pronounced in
October as distribution of calanoids was more uniform throughout the
study area.
Four species of Diaptomus were observed in the Straits region. Diaptomus
oregonensis was most abundant (4% of total Crustacea) and was decidedly
more prevalent west of the Mackinac Bridge and in the South Channel during
August and September (Fig. 7.4). This species was considerably less
abundant in October and its distribution was more uniform. Adults of
D. minutus were also most prevalent west of the Mackinac Bridge and in
the South Channel in August (Fig. 7.5) . In September and October, it was
low in abundance and more evenly distributed throughout the Straits area.
Adults of D. ashlandi and D. sicilis were relatively low in abundance
throughout the study period and comprised near 1% and 0.5%, respectively,
of total Crustacea during each cruise. Numbers of D. ashlandi decreased
while numbers of D. sicilis increased throughout the study period. No
distinct pattern of distribution was observed for D. ashlandi, but D.
sicilis was somewhat more abundant towards Lake Huron (Figs. 7.6 and 7.7).
Whereas adults of most diaptomids, especially D. oregonensis and D.
minutus, were most prevalent towards Lake Michigan and in the South Chan-
nel, copepodids of Diaptomus spp. were distinctly most abundant,
especially during August and September, towards Lake Huron and north of
Bois Blanc Island (Fig. 7.8). Recruitment of young copepods into the
population is indicated throughout the study period as numbers of
Diaptomus copepodids increased from an average of 2,893/m3 in August to
5,968/m3 in October. They comprised an average of about 30% of total
Crustacea in August and September and 53% in October. Since Diaptomus spp.
copepodids were so abundant, the distribution pattern noted for total
calanoids (Fig. 7.3) largely reflects the distribution of Diaptomus spp.
copepodids (Fig. 7.8).
The other calanoid copepods, Limnocalanus, Senecella, and Epischura, were
low in relative abundance throughout the study period but exhibited dis-
tinct patterns of distribution. Limnocalanus was decidedly more abundant
140
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TOTflL CRUSTflCEfl/M3
17-19 SEPTEMBER 1973
TOTflL CRUSTflCEfl/M»
6-8 OCTOBER 1973 t-
Flgure 7.2. DISTRIBUTION AND ABUNDANCE
(NUMBERS OF INDIVIDUALS PER M3) OF TO-
TAL CRUSTACEAN ZOOPLANKTON IN THE
STRAITS OF MACKINAC ON THREE CRUISES,
1973.
141
-------
CflLflNOIOS/M*
30 flUG - 1 SEPT 1973 5—TsSoO
CflLHNOIOS/M»
17-19 SEPTEMBER 1973 J
CflLflNOIDS/M*
$-8 XTOBER 1973
Z CflLflNOIOS
30 HUG - 1 SEPT 1973
Z CRLfWOIDS
SEPTEMBER 1973
Z CflLflNOIDS
6-6 OCTOBER 1S73 6
Figure 7.3. DISTRIBUTION AND ABUNDANCE (NUMBERS PER M3 AND PERCENT COMPOSI-
TION) OF CALANOID COPEPODS IN THE STRAITS REGION.
142
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DIRPTOHUS OFEGONENSIS/M3
30 flUG - 1 SEPT 1973 , • •
OREGONENSIS
30 flUG - 1 SEPT 1973
DIflPTOMUS OREGQNENSIS/tf
17-19 SEPTEMBER 1973
% OlftPTOMUS OREGONENSIS
17-19 SEPTEMBER 1973
7. DIflPTOMUS OREGONENSIS
6-8 OCTOBER 1973
DlfiPTOMUS OREGONENSIS/M3
6-8 OCTOBER 1973
Figure 7.4. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS OREGONENSIS IN THE
STRAITS REGION.
143
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DIfiPTOMUS NINUTUS/N*
30 flUG - I SEPT 1973 & ' ' t5bo
DIflPTOMUS MINUTUS/M*
J7-I9 SEPTEMBER 1973 >—>—'-T&Q
DIflPTOMUS MINUTUS/H1
6-8 OCTOBER 1973 t—'—>~i3nn
Z DIflPTOMUS HINUTUS
30 HUG - I SEPT 1973
OlflPTOMUS HINUTUS
6-6 OCTOBER 1973 ft •
Figure 7.5. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS MINUTUS IN THE
STRAITS REGION.
144
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DIflPTOMUS RSONDI/M"
30 BUG - 1 SEPT 1973
DlfVTOHUS fiSHLWOI/H5
17-19 SEPTQBER 1973
DlflPTOMUS BSHLflNDl/H'
6-8 OCTOBER 1973
Z OlflPTQMUS flSHLflNDI
30 HUG - 1 SEPT 1973
X OlflPTOMUS flSHLfWDI
17-19 SEPTEMBER 1973 t
Z DIflPTOMUS RSHLflNDI
6-6 OCTOBER 1973
Figure 7.6. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS ASHLANDI IN THE
STRAITS REGION.
145
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DlflPTOMUS SICILIS/M*
30 RUG - 1 SEPT 1973
DlflPTOMUS SICILIS/M*
17-19 SEPTEMBER 1973 g-
X DlflPTOMUS SICILIS
30 HUG - 1 SEPT 1973 *
X DlflPTOMUS SICILIS
17-19 SEPTEMBER 1973
DIRPTOMUS SICILIS/M8
6-8 OCTOBER 1973
X DIRPTOMUS SICILIS
6-8 OCTOBER 1973
Figure 7.7. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS SICILIS IN THE STRAITS
REGION.
146
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OlflPTOMUS SPP. COPEPOOIOS/M*
30 flUG - 1 SEPT 1373 0
DlflPTOMUS SPP. COPEPOOIDS/M8
17-19 SEPTEMBER 1973
DlflPTOMUS SPP. COPEPODIOS/M*
6-8 OCTMER 1973 t—•-
Z DlflPTOMUS SPP. COPEPOOIDS
30 BUG - 1 SEPT 1973 H-H
2 DlflPTOMUS SPP. COPEPODIOS
17-19 SEPTEMBER 1973 *-*-
Z DlflPTOMUS SPP. COPEPOOIDS
6-8 OCTOBER 1973
Figure 7.8. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS SPP. COPEPODIDS IN THE
STRAITS REGION.
147
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in open waters towards Lake Huron (Fig. 7.9). For example, the average
abundance of Limnocalanus during all cruises at stations west of the
Mackinac Bridge was 2.3 individuals/m3 (0.04% of total Crustacea), where-
as abundance of this species (86.3/m3 or 0.6% of total Crustacea) was
distinctly greater along the transect of stations from Cordwood Point to
Government Island toward Lake Huron. As to be expected from this cold-
water stenothermic species, Limnocalanus was most prevalent at offshore
stations (Fig. 7.9). The other cold-water stenotherm, Senecella, exhibited
a pattern of distribution similar to Limnocalanus. Senecella was absent
from stations toward Lake Michigan and in the South Channel and was most
abundant at offshore stations toward Lake Huron (Fig. 7.10). In contrast,
Epischura was more abundant toward Lake Michigan and in the South Channel
than in the Lake Huron portion of the Straits region. It was somewhat
more abundant at nearshore stations, especially in South Channel
(Fig. 7.11).
Cyclopoid copepods were considerably less prevalent in the Straits region
than either calanoid copepods or cladocerans. Average abundance of
cyclopoid copepods ranged from 232-1,018/m3 during the study period.
During Cruises 1, 2, and 3, they comprised 5, 4, and 9%, respectively, of
total crustacean plankton. The cyclopoid copepods did not exhibit any
striking distribution patterns within the Straits region (Fig. 7.12).
The cyclopoid copepods were composed almost entirely of one species,
Cyclops bicuspidatus thomasi, which comprised over 97% of total cyclopoids
during the study period. Obviously, the relatively uniform distribution
of total cyclopoids (Fig. 7.12) is due to the distribution of Cyclops
bicuspidatus thomasi (Fig. 7.13). Mesocyclops edax, although low in
numbers, was slightly more prevalent towards Lake Huron in August and
September but was more evenly distributed throughout the study area in
October (App. F.l-3). Tropocyclops prasinus mexicanus was likely under-
sampled by the mesh size of the net utilized in this investigation. It
was collected sporadically at stations throughout the study area during
August and September (App. F.l-2).
The Cladocera constituted a significant portion of crustacean plankton,
particularly in August when they averaged 53% of total Crustacea. Actual
numbers were highest in October (average 4,541/m3), but Cladocera com-
prised only 35% of total Crustacea due to increased abundance of copepods
at this time. The Cladocera were distinctly more abundant towards Lake
Michigan and in the South Channel than towards Lake Huron (Fig. 7.14).
This trend was most prominent in August and September. There was also a
trend for Cladocera to be more prevalent at stations near shore (Fig. 7.14).
Daphnia galeata wendotae was the most abundant cladoceran throughout the
study period. It averaged 1,401 individuals/m3 in August and comprised
17% of total Crustacea. This species exhibited a distinct pattern of
greatest abundance towards Lake Michigan and in the South Channel
(Fig. 7.15). A similar pattern was observed in September, but patchier
distribution was noted in October. It was most abundant in nearshore
148
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L1MNOCHLRNUS MRCRURUS/KP
30 (WG - 1 SEPT 1973
UMNOCflLRNUS MBCRURUS/M9
17-19 SEPTEMBER 1973 *—i
LIMNOCfiLflNUS MBCBURUS/H*
6-8 OCTOBER 1973 i—•
LIMNOCflLflNUS MflCHJRUS
30 RUG - 1 SEPT 1973
X LINNOCflLflNUS MfCTUflUS
6-8 OCTOBER 1973
Figure 7.9. DISTRIBUTION AND ABUNDANCE OF LIMNOCALANUS MACRURUS IN THE
STRAITS REGION.
149
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SENECELLR CFLFWOIDES/H*
30 flUG - 1 SEPT 1973
SENECELLfl CfWJ*IOIDES/M»
17-19 SEPTEMBER 1973
X SENECELLFI CN.RN01DES
30 HUG - 1 SEPT 1973 ' ' '
SENECELLH tflLflNOIOES/M*
6-8 OCTOBER 1973 t—"—•—"-51.
X SENECELLR CHLWOIDES
17-19 SEPTEMecn 1973 ' • '
X SENECELLFI CflLRNOIOES
6-8 OCTOBER 1973 t—'—•-
Figure 7.10. DISTRIBUTION AND ABUNDANCE OF SENECELLA CALANOIDES IN THE
STRAITS REGION.
150
-------
EPISCHURfl LflCUSTRIS/M8
30 HUG - 1 SEPT 1973 ft • • i^fa
Z EPISCHURfl LfiCUSTRIS
30 flUG - 1 SEPT 1973 g-
EPISCHURft LflCUSTHIS/M*
17-19 SEPTEMBER 1973 ft i i -^
% EPISCHUm LflCUSTRIS
17-19 SEPTEMBER 1973
Z EPISCHURfl LflCUSTRIS
8-8 OCTOBER 1973
EPISCHURfl LBCUSTRIS/M»
6-8 OCTOBER 1973 fl • • '^
Figure 7.11. DISTRIBUTION AND ABUNDANCE OF EPISCHVRA LACUSTRIS IN THE
STRAITS REGION.
151
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X CYCLOPOIOS
30 RUG - 1 SEPT 1973
CTCLOPOIDS/M*
30 BUG - 1 SEPT 1973 g
CTCLOPOIDS/M'
17-19 SEPTEMBER 1973 *
V. CTCLOPOJOS
17-19 SEPTEMBER 1973 t
7. CYCLOPOIOS
6-8 OCTOBER 1973
CYODPOIDS/M'
6-8 OCTOBER 1973 fr
Figure 7.12. DISTRIBUTION AND ABUNDANCE OF CYCLOPOID COPEPODS IN THE
STRAITS REGION.
152
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X CYCLOPS BICUSPIDflTUS THOMRSI
30 RUG - 1 SEPT 1973
CYCLOPS BICUSPIDRTUS THOMBSI/M8
30 flUG - I SEPT 1973 ..
CYCLOPS BICUSPIORTUS THOMflSJ/H*
17-19 SEPTEMBER 1973
Z CYCLOPS BICUSPIOHTUS THOMfiSI
17^19 SEPTEMBER 1973
Z CYCLOPS BICUSPIDfiTUS THOMHSI
CYCLOPS BICUSPJDflTUS THOMflSI/M'
B-8 OCTOBER 1973 ±—•
Figure 7.13. DISTRIBUTION AND ABUNDANCE OF CYCLOPS BICUSPIDATUS THOMASI
IN THE STRAITS REGION.
153
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CLftDOCERfl/M»
30 «JG - 1 SEPT 1973
% CLHXKERfl
30 BUG - 1 SEPT 1973 Q ' ' ' ' too
CLflDOCERH/M5
17-19 SEPTEMBER 1973
6-8 OCTOBER 1973
CLROOCEHR
17-19 SEPTEMBER 1973
X CLFOOCERfl
6-6 OCTOBER 1973
Figure 7.14. DISTRIBUTION AND ABUNDANCE OF CLADOCERA IN THE STRAITS
REGION.
154
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ORPHNIR GRLERTR MENOOTRE/H*
30 BUG - 1 SEPT 1973 . . .
OflPHNIH GflLEflTR MENDOTflE/M'
17-19 SEPTEMBER 1973
DflPHNIfl GflLERTfl MENDOTRE/M8
6-8 OCTOBER 1973
Z ORPHNIR GflLERTA HENDOTflE
30 BUG - 1 SEPT 1973 g—»-
Z DRPHNIft GHLERTA HENOOTRE
17-19 SEPTEWER 1973 —«-
X ORPHNlfl GflLERTft MENOOTRE
6-B OCTOBER 1973 j
Figure 7.15. DISTRIBUTION AND ABUNDANCE OF DAPHNIA GALEATA MENDOTAE IN THE
STRAITS REGION.
155
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areas, especially off the islands and the north shore of the study area
during October (Fig. 7.15).
Daphnia retrocurva was also an abundant cladoceran in the Straits region
where it comprised an average of near 10% of total Crustacea during
August and September. Its contribution (4%) to total Crustacea was
considerably less during October. This species was predominantly distrib-
uted in waters toward Lake Michigan and in the South Channel during all
three cruises (Fig. 7.16). It was also more abundant at nearshore
stations.
In contrast to D. galeata mendotae and D. retrocurva, D. longiremis was
less abundant and its patterns of distribution were not as distinctive.
Daphnia longiremis comprised an average of 4, 3, and 1% of total
Crustacea during August, September, and October, respectively. It was
most abundant north of the islands in August; no decisive pattern was
evident in September and October (Fig. 7.17).
Holopedium gibberum was an important constituent of the plankton community
in the Straits region. It was most abundant during August when an average
of 905/m3 or 5% of total Crustacea was observed. Holopedium exhibited
greatest abundance in waters toward Lake Michigan and in the South Chan-
nel, especially during August and September (Fig. 7.18). Its distribu-
tion in October was less distinct, with some tendencies to be more
prevalent near shore.
The carnivorous species Leptodora kindtii was never sufficiently abundant
to comprise 1% of total Crustacea. However, it was distributed through-
out the study area and was considerably more abundant toward Lake Michigan
and in the South Channel (Fig. 7.19). The other carnivorous cladoceran,
Polyphemus pediculus, was less abundant than L. kindtii, but its distri-
bution pattern was strikingly similar, especially in August and September
(App. F.l-3).
Eubosmina coregoni was approximately two to three times more abundant in
the Straits region than Bosmina longirostris. The relative abundance of
E. coregoni decreased from 7% of total Crustacea in August to 3% in
October while B. longirostris increased slightly from 1% in August to 2%
in October. The distribution patterns of the two species were notably
different; E. coregoni was most characteristic of waters towards Lake
Michigan and in the South Channel (Fig. 7.20), B. longirostris was most
prevalent near the north shore especially at the mouth of the St. Marys
River as well as shallow stations elsewhere (Fig. 7.21).
The remaining Cladocera were present in low levels of abundance, consid-
erably less than 1% of total Crustacea. Diaphanosoma leuchtenbergianum
was distributed throughout the Straits region during the study period.
Its distribution was exceedingly irregular in August and September. In
October, it was most prevalent along the north shore and another patch
of relative abundance was noted at Station 16 in the South Channel
156
-------
DRPM41R RETROCURVR
30 RUG - 1 SEPT J973
OflPHNIfi RETROCURVR/M»
30 flUG - 1 SEPT 1973
DfiPHNIfi RETHOCUHVB/N9
17-19 SEPTEMBER 1973 *
OflPHNIfl RETROCURVfl/M9
6-8 OCTOBER 1973 t-
OflPWJIfl RETROORVR
17-19 SEPTEMBER 1973 t
Z DflPHNIH RETROCURVR
6-6 OCTOBER 1973
Figure 7.16. DISTRIBUTION AND ABUNDANCE OF DAPHNIA RETROCURVA IN THE
STRAITS REGION.
157
-------
DflPHNIfl LONGIREHIS/M*
30 HUG - I SEPT 1973
DflPHNIfl LONGIREMIS/M*
17-19 SEPTEMBER 1973
DflPHNIfl LONGIFEMIS/M5
6-8 OCTOBER 1973
Z DOPHNIfl LOMGIREHIS
30 flUG - 1 SEPT 1973
% DflPHNlfl LONGIBEMIS
17-19 SEPTEHBER 1973
Z DRPHNIR LONGIREMIS
6-6 OCTOBER 1973
Figure 7.17. DISTRIBUTION AND ABUNDANCE OF DAPHNIA LONGIREMIS IN THE
STRAITS REGION.
158
-------
HOLOPEDIUN GI8BERUM/M8
30 BUG - 1 SEPT 1973
% HOLOPEOIUM GIBBERUM
30 BUG - 1 SEPT 1973 K
HOLOPEOIUM GIBBERUM/M8
17-19 SEPTEMBER 1973
7. HOLOPEOIUM GIBBERUM
17-19 SEPTEMBER 1973
Z HOLOPEOTUH GIBBEBUM
6-6 OCTOBER 1973
HQLOPEDIUM GIBBEflUM/K5
6-8 OCTOBER 1973
Figure 7.18. DISTRIBUTION AND ABUNDANCE OF HOLOPEDIUM GIBBERUM IN THE
STRAITS REGION.
159
-------
LEPTODORR KINDTII/M8
30 BUG - I SEPT 1973
LEPTODOflfl KINDTII/M8
17-19 SEPTEMBER 1973
LEPTODORfl KINOTII/M8
6-6 OCTOBER 1973 t
% LEPTOOOfW KINDTII
30 RUG - 1 SEPT 1973
'/. LEPTOOOFW KINDTII
17-19 SEPTEMBER 1973
2 LEPTODORR KINDTII
6-8 OCTOBER 1973
Figure 7.19. DISTRIBUTION AND ABUNDANCE OF LEPTODORA KINDTII IN THE
STRAITS REGION.
160
-------
EUBOSMINfi COREGONI/tP
30 flUG - 1 SEPT 1973
EUBOSMINfl COREGON1/M3
17-19 SEPTEMBER 1973
EUBOSMINR COREGONI/M5
6-6 OCTOBER 1973 Jt—
Tsbo
EUBOSHINfl COFEGQNI
30 flUG - 1 SEPT 1973
'/. EUBOSMINf) COREGONI
17-19 SEPTEMBEfl 1973
X EUBOSHINfl COHEGONI
6-6 OCTOBER 1973
Figure 7.20. DISTRIBUTION AND ABUNDANCE OF EUBOSMINA COREGONI IN THE
STRAITS REGION.
161
-------
BOSMINfl LONGIROSTHIS/MS
30 HUG - 1 SEPT 1973
Z BOSMINB LONGIROSTfUS
30 flUG - 1 SEPT 1973 £—•
BOSHJNR UMGIROSTRIS/M9
17-19 SEPTQ^R 1973
% BOSHlNfi LONGIFOSTRIS
17-19 SEPTEMBER 1973
Z BOSMINR LONGIROSTFirS
e-6 OCTOBER 1973
BOSMINfi LONGIHOSTBIS/M5
6-8 OCTOBER 1973
Figure 7.21. DISTRIBUTION AND ABUNDANCE OF BOSMINA LONGIROSTRIS IN THE
STRAITS REGION.
162
-------
(Fig. 7.22). Ceriodaphnia lacustris, C. guadrangula, and Chydorus
sphaericus were observed throughout the Straits region but exhibited no
noteworthy patterns of distribution, sida crystallina, a littoral species
was observed only in September near the mouth of the St. Marys River '
Other species were predominantly littoral forms that occasionally appeared
as one or two individuals at nearshore stations (App. P.1-3) .
In summary, the preceding simple inspection of data reveals that there
were differences in the community structure of crustacean zooplankton
within the Straits of Mackinac. Although the species composition was
practically identical at every station, prominent and consistent patterns
were evident in the relative proportions of species to one another in
specific subregions within the Straits. The relative abundance of zoo-
plank ters towards Lake Michigan (west of the Mackinac Bridge) and in the
South Channel (south of Bois Blanc Island) shared many resemblances.
This region was characterized by a distinct preponderance of cladocerans,
especially Daphnia retrocurva and D. galeata mendotae. Other cladocerans,
such as Holopedium gibberum, Eubosmina coregoni, Leptodora kindtii, and
Polyphemus pediculus, were also most prevalent in this region. In addi-
tion, the calanoid copepods Epischura lacustris, Diaptomus oregonensis,
and D. minutus were generally characteristic of this region. In contrast,
calanoid copepods as a group were relatively most abundant in waters
towards Lake Huron, i.e., north and east of Bois Blanc Island. The pre-
ponderance of calanoid copepods in this region was mainly due to
copepodids of Diaptomus spp., D. sicilis adults, Limnocalanus macrurus
and Senecella calanoides. Cyclopoid copepods, predominantly Cyclops
bicuspidatus thomasi, did not show any distinctive trends but appeared
somewhat more prevalent toward Lake Huron. Cladocerans, such as Bosmina
longirostris, were mainly characteristic of inshore stations in this
region.
Principal component analysis (PCA) allowed us to more clearly observe
some of these trends and defined other trends not discernible simply by
inspection. Two major regions, here arbitrarily termed L and M, were
deliniated by PCA based upon similarities in relative abundance of zoo-
plankters at various stations. The L region lies toward Lake Michigan
and in the South Channel while the M region consists of waters towards
Lake Huron and north of Bois Blanc Island. On August and October cruises,
the M region was divided into two subregions, M east of Bois Blanc Island
and N north of the island. The N subregion was not sampled due to inclem-
ent weather during the September cruise. These major regions were
remarkably consistent both in areal coverage and in species associations
throughout the study (Figs. 7.23-7.25).
During the August cruise, the waters toward Lake Michigan and in the
South Channel (L2) were characterized by a greater relative abundance of
Daphnia retrocurva, D. galeata mendotae, Holopedium gibberum, Eubosmzna
coregoni, Epischura lacustris, Diaptomus oregonensis, and D. nunutus
(Fig. 7.23). Stations within the Lj subregion showed the greatest affin-
ities due to a preponderance of Daphnia galeata mendotae D. retrocurva,
and Diaptomus minutus (Table 7.2). L3 was characterized by greater
163
-------
DlfiPHflNOSOHfl LEUCHTENBERGIflNUM/lP
30 RUG - 1 SEPT 1973 £
DIflPHflNOSOMH LEUCKTENBEBGIflNUM/M*
17-19 SEPTEMBEft 1973 (j—i
DIflFHflNOSOMfi LEUCHTENBEHGIflNUH/Ma
6-8 OCTOBER 1973 g—'—i
Z OlflPHflNOSOMB LEUCHTENBERGIfNJM
30 flUG - 1 SEPT 1973 g
Z OlflPmNOSOMft LEUCKIENBERGIFHJH
17-19 SEPTEMBER 1973
Z OlftPHFWOSOMfl LBJCHTENBERCIflNUH
B-6 OCTOBER 1973 i—«
Figure 7.22. DISTRIBUTION AND ABUNDANCE OF DIAPHANOSOMA LEUCHTENBERGIANUM
IN THE STRAITS REGION.
164
-------
Figure 7.23. ZONES OF SIMILARITY IN COMMUNITY STRUCTURE OF CRUSTACEAN ZOOPLANKTON IN THE STRAITS
REGION DURING AUGUST 1973. These zones, arbitrarily labeled L, M, and N, were determined by
principal component analysis using percent composition of 16 species.
-------
DETOUR
PASSAGE
-84M5'
Figure 7.24. ZONES OF SIMILARITY IN COMMUNITY STRUCTURE OF CRUSTACEAN ZOOPLANKTON IN THE
STRAITS REGION DURING SEPTEMBER 1973 AS DETERMINED BY PRINCIPAL COMPONENT ANALYSIS.
-------
ON
•-J
two = 84«OCT
Figure 7.25. ZONES OF SIMILARITY IN COMMUNITY STRUCTURE OF CRUSTACEAN ZOOPLANKTON IN THE
STRAITS REGION DURING OCTOBER 1973 AS DETERMINED BY PRINCIPAL COMPONENT ANALYSIS.
-------
Table 7.2. DISTRIBUTION OF ZOOPLANKTON DURING AUGUST 1973. Relative abun-
dances (in percent composition) for each region (Fig. 7.23) are given over
the standard error of the mean. Standard errors are omitted when values
used in the average are identical. Taxa are grouped according to apparent
trend. Taxa most abundant in Lj are listed first, and those most prevalent
in MI appear last.
Region and number of stations
Daphnia retrocurva
Epischura lacustris
Diaptomus minutus
Holopedium qibberum
Eubosmina coregoni
Daphnia galeata mendotae
Diaptomus oregonensis
Leptddora kindtii
Polyphemus pediculus
Mesocyclops edax
Daphnia longiremis
Ceriodaphnia lacustris
Bosmina longirostris
Diaptomus ashj.andi
Cyclops bicuspidatus thomasi
Diaptomus sicilis
Diaptomus spp. copepodids
Limnocalanus macrurus
Li
4
17.2
4.4
1.4
.1
10
3
16
3
11
1
28
3
4.1
1.3
.56
.04
.14
.09
.11
.07
1.6
.9
.09
.05
.38
.13
.54
.02
1.7
-4
.02
.02
6.1
.5
0
L2
10
15
3
1.3
.2
7.9
1.3
14
1
8.5
1.1
23
1
6.2
1.1
.91
.16
.41
.13
.21
.14
2.7
.5
.08
.03
.46
.14
1.1
.1
3.5
.4
.02
.02
13
2
.02
.02
L3
8
11
2
1.2
.2
4.4
.7
15
1
7.8
.5
18
1
5.6
.8
.73
.14
.19
.08
.15
.06
3.4
1.0
.13
.03
.84
.31
1.69
.08
6.0
.5
.01
.01
22
3
.07
.03
NI N2
1 3
8.5 5.4
.4
.59 .55
.17
.77 1.4
.5
6.8 6.2
1.7
3.2 2.8
.3
8.1 8.7
.5
4.2 3.1
.6
.47 .66
.50
.09 .02
.02
.09 -09
.03
13 11.1
.6
.26 .10
-05
1.7 1.8
.4
3.9 1.8
.2
6.1 6.8
.6
0 .05
.04
41 48
3
0 .15
.14
M2
9
5.7
.7
.63
.12
2.1
.5
7.0
.7
3.7
.3
10.5
.7
2.1
.4
.28
.06
.15
.06
.13
.06
4.8
.7
.05
.01
1.1
.2
1.51
.07
5.9
.5
.16
.05
52
2
.46
.20
MI
1
1.0
.31
1.2
3.4
1.3
3.2
.57
.11
.05
.02
.87
0
.30
.48
2.1
.05
84
.38
168
-------
relative abundance of Diaptomus oregonensis. Stations in the M region
northeast of Bois Blanc Island showed affinities based upon greater
relative abundance of Diaptomus sicilis, Diaptomus spp. copepodids and
Limnocalanus macrurus. These species also comprised a major constituent
in the N region northwest of Bois Blanc Island, but this region was more
characterized by the relative abundance of Diaptomus ashlandi, Daphnia
longiremis, Bosmina longirostris, and Cyclops bicuspidatus thomasi
(Fig. 7.23). Only one (Mesocyclops edax) of the 16 species analyzed did
not show any strong trends in distribution during August (Table 7.2).
Trends in species associations were strongest during the September cruise,
a period characterized by strong westerly winds (Fig. 7.24). The L
region was characterized by the same species predominance as observed in
August. Daphnia retrocurva, D. galeata mendotae, and Diaptomus
oregonensis were most prevalent in the Lj subregion, while Holopedium
gibberum and Epischura lacustris most characterized the 1,3 subregion.
The M region was also characterized by the same predominant species as in
August. Stations in the MI subregion had a relatively greater abundance
of Diaptomus spp. copepodids, D. sicilis, Limnocalanus macrurus, and
Bosmina longirostris, while the MS subregion had more Cyclops bicuspidatus
thomasi (Fig. 7.24). Only Mesocyclops edax, Daphnia longiremis. and
Diaptomus ashlandi did not show any strong trends in distribution during
this cruise (Table 7.3).
Trends in relative abundance of zooplankters were least distinct during
the October cruise, when weak easterly winds were blowing (Fig. 7.25).
The L region included the same species predominance as the previous
cruise with the addition of Mesocyclops edax and Eubosmina coregoni and
the exclusion of Holopedium gibberum and Daphnia galeata mendotae. The
LI subregion was predominated by Daphnia retrocurva, Diaptomus ashlandi,
D. oregonensis, Epischura lacustris, and Leptodora kindtii while 1*2 was
characterized by a greater preponderance of Eubosmina coregoni and
Diaptomus minutus. The M and N subregions were more distinct from one
another than on previous cruises. Daphnia longiremis, D. galeata mendotae,
and Holopedium gibberum were most prevalent in the N subregion while, as
in previous cruises, Diaptomus spp. copepodids, D. sicilis and Limnocalanus
macrurus characterized the M subregion (Fig. 7.25). Station 40, inshore
in the extreme southeastern corner of the study area, was an entity in
itself during this cruise. It contained strong characteristics of both
L and N regions with a preponderance of Epischura lacustris, Leptodora
kindtii, Daphnia longiremis, D. galeata mendotae, and Holopedium gibberum
(Fig. 7.25). Only Cyclops bicuspidatus thomasi and Bosmina longirostris
were not characteristic of any particular portion of the Straits region
during this cruise (Table 7.4).
The distribution and abundance of crustacean zooplankton is related to
temperature, food requirements, and competitive interactions among
species. Our understanding of the interrelationships between physico-
chemical and biological factors expressed in different growth and repro-
duction rates of various species is indeed meager. Nevertheless, the
169
-------
Table 7.3. DISTRIBUTION OF ZOOPLANKTON DURING SEPTEMBER 1973. Relative
abundances (in percent composition) for each region (Fig. 7.24) are
given over the standard error of the mean. Taxa are grouped according
to apparent trend. Taxa most abundant in Lj are listed first, and those
most prevalent in M^ appear last.
Region and number of stations
Leptodora kindtii
Diaptomus oregonensis
Daphnia retrocurva
Diaptomus minutus
Eubosmina coregoni
Daphnia, galeata mendotae
Epischura lacustris
Holopedium gibberum
Diaptomus ashlandi
Daphnia longiremis
Mesocyclops edax
Bosmina longirostris
Cyclops bicuspidatus thomasi
Diaptomus sicilis
Diaptomus spp. copepodids
Limnocalanus macrurus
Ll
4
1.3
.2
9.0
1.9
19
3
2.4
.5
2.6
.3
42
5
2.9
.9
4.2
.9
1.1
.3
2.8
1.3
.04
.04
0
2.1
.6
0
8.7
2.5
0
L2
7
1.14
.08
5.9
3.2
17
2
1.9
.5
3.1
.5
38
4
3.8
.9
5.6
1.2
.60
.13
3.4
.7
.20
.09
.27
.21
1.8
.4
.11
-04
15
4
.09
.06
L3
6
.74
.31
7.1
1.1
14.1
.5
.81
.18
1.4
.3
35
3
2.3
.6
4.0
1.3
1.6
.6
4.2
1.1
.13
.09
.13
.10
3.9
1.1
.02
.02
22
2
.05
.03
M3
11
.35
.05
2.6
.6
7.6
1.3
1.1
.2
2.0
.3
15
2
1.5
.2
2.2
.3
.85
.15
3.2
.6
.22
.07
-63
.22
6.0
1.3
.21
.08
55
3
.90
.31
M2
6
.16
.06
1.1
.2
4.1
.8
.18
.10
.65
.23
9.2
1.5
.65
.23
1.3
.3
.35
.05
2.1
.3
.10
.03
1.4
.2
3.9
.4
.18
.04
73
2
.77
.26
MI
6
.07
.01
.62
.16
1.9
.4
.15
.08
.33
.08
6.5
1.4
.50
.16
1.2
.2
.33
.07
1.8
.3
.09
.02
2.1
.7
4.3
.5
.31
.04
78
3
1.5
.6
170
-------
Table 7-4. DISTRIBUTION OF ZOOPLANKTON DURING OCTOBER 1973. Relative
abundances (in percent composition) for each region (Fig. 7.25) are given
over the standard error of the mean. Standard errors are omitted when
values used in the average are identical. Taxa are grouped according to
apparent trend. Taxa most abundant in Lj are listed first, and those most
prevalent in M^ appear last.
Region and Number
Epischura lacustris
Daphnia retrocurva
Diaptomus minutus
Diaptomus ashlandi
Leptodora kindtii
Mesocyclops edax
Diaptomus oregonensis
Eubosmina coregoni
Cyclops bicuspidatus thomasi
Bosmina longirostris
Daphnia longiremis
Holopedium gibberum
Daphnia galeata mendotae
Diaptomus spp. copepodids
Diaptomus sicilis
Limnocalanus macrurus
Li
3
4.2
.9
9.5
1.1
.75
.24
1.5
-4
.45
-04
.34
.10
1.5
.2
2.6
1.0
8.0
.8
1.7
.9
.10
.02
1.8
.4
15.4
.6
49
2
.15
.11
0
L2
10
2.5
.4
5.8
.7
.90
.14
.92
.15
.15
.03
.30
.06
1.0
.2
4.4
.5
9.3
2.1
1.0
.2
.33
.13
3.2
.7
18-
2
48
3
.27
.08
.01
.01
LN NI
1 9
12 .64
.21
4.9 4.0
.7
.61 .24
-05
0 -47
.09
.46 .06
.03
.15 .09
-05
.15 .88
.16
.61 2.1
.2
10 7.3
.5
2.8 1.9
.3
.76 1.4
.4
20 8.5
1.1
38 30
2
10 40
2
0 .32
.07
0 -02
-01
of stations
N2
8
.57
.12
2.7
.5
.17
.08
.34
.08
.09
.03
.14
.04
.52
.10
2.7
.2
9.6
1.5
3-6
1.4
.53
.09
5.8
1.3
17
53
1
-43
.09
.21
.09
M2
12
.90
.29
2.0
.3
.32
.06
.32
.04
.08
.02
.11
.03
.78
.10
2.4
.3
8.9
.5
1.4
.2
.71
.12
3.6
.4
14
62
1
.63
.09
.31
.18
MI
7
.43
.17
1.7
.3
.12
.04
.15
.02
.16
.04
.09
.03
1.0
.1
1.9
.3
7.3
.9
1.9
.6
.35
.08
3.0
.7
11
68
2
.71
.08
1.3
.6
171
-------
distribution and abundance of crustacean zooplankton observed in the
Straits of Mackinac region are interpretable in light of our knowledge
of responses of zooplankton communities to different trophic conditions.
Calanoid copepods generally appear best adapted^ for oligotrophic condi-
tions in the Great Lakes. In more eutrophic waters, cladocerans,
cyclopoid copepods, and rotifers are relatively more abundant than
calanoid copepods. This trend has been observed in Lakes Superior,
Huron, Erie, and Ontario by Patalas (1972) and in Lake Michigan by
Gannon (1972a; 1972b; 1974b; 1975). In the Straits of Mackinac, the
simple ratio of calanoid copepods to cyclopoid copepods and cladocerans
appeared to be an indicator of trophic conditions (Figs. 7.26-7.28).
Higher values were generally obtained towards Lake Huron and lower values
towards Lake Michigan during each cruise. The actual numbers obtained
in this simple ratio do not seem important but relative differences from
station to station are revealing. Monitoring changes in the ratio of
calanoid copepods to cladocerans and cyclopoid copepods during summer
stratification may be a useful indicator of eutrophication trends in the
Great Lakes.
In summer, even though physicochemical characteristics of water at various
stations in the Straits region differed only subtly, distinct water masses
were identified. Similarities between water masses discerned by cluster
analyses (see Sec. V) and regions of homogeneity in zooplankton community
structure (Figs. 7.23-7.25) were remarkable. Cladocerans were relatively
most abundant in the slightly more eutrophic waters towards Lake Michigan
and in the South Channel, while calanoid copepods prevailed in the
slightly more oligotrophic waters towards Lake Huron; Although the species
of crustacean zooplankton were nearly identical throughout the study area,
the community structure appeared to be a sensitive indicator of water
quality even in the waters of the Straits region where nutrient conditions
differ so subtly.
Northern Lake Michigan
All of the eulimnetic crustacean zooplankton noted in the Straits region
were observed in northern Lake Michigan during September except
Tropocyclops prasinus wexicanus and Polyphemus pediculus (App. F.4).
Littoral and benthic species were absent iti the plankton except for a few
individuals of Acroperus harpae at the shallowest station (10 m) off the
Sturgeon Bay Ship Canal. Mysis relicta was observed in the plankton at
most stations greater than 120 m deep. Pontoporeia affinis was observed
in the plankton only at Station 24, 164 m deep (App. F.4).
Average numbers of crustacean zooplankton were considerably lower at
stations in northern Lake Michigan (1,537/m3) than in the Straits region
(5,014/m3) in September (Fig. 7.29). Highest numbers (>3,000/m3) were
noted at an inshore station near Sturgeon Bay and stations nearest the
Straits region. The lowest numbers (
-------
CLADOCERA + CYCLOPOIDA
AUGUST, 1973
Figure 7.26. THE RATIO OF CALANOID COPEPODS TO CLADOCERANS AND CYCLOPOID COPEPODS
IN THE STRAITS REGION DURING AUGUST 1973.
-------
CLADOCERA + CYCLOPOIDA
SEPTEMBER .1973
Figure 7.27. THE RATIO OF CALANOID COPEPODS TO CLADOCERANS AND CYCLOPOID COPEPODS
IN THE STRAITS REGION DURING SEPTEMBER 1973.
-------
CLADOCERA + CYCLOPOIDA
OCTOBER,1973
Figure 7.28. THE RATIO OF CALANOID COPEPODS TO CLADOCERANS AND CYCLOPOID COPEPODS
IN THE STRAITS REGION DURING OCTOBER 1973.
-------
TOTflL CRUSTRCEfl/M3
6 ' ' ' 10000
Figure 7.29. DISTRIBUTION AND ABUNDANCE (NUMBERS OF INDIVID-
UALS PER M3) OF TOTAL CRUSTACEAN ZOOPLANKTON IN NORTHERN
LAKE MICHIGAN DURING SEPTEMBER 1973.
deepest offshore stations. Calanoid copepods and cladocerans each com-
posed about half of the crustacean zooplankton. Cyclopoid copepods
represented a minor component in the fauna. Predominant species were
Daphnia galeata roendotae and D. retrocurva followed by Limnocalanus
macrurus, Diaptomus oregonensis, Eubosmina coregoni, and Diaptomus
sicilis.
Calanoid copepods comprised an average of 51% of total Crustacea
(Fig. 7.30). Approximately half of the calanoids were Diaptomus spp.
copepodids. These immature copepods did not exhibit any appreciable
pattern of distribution in northern Lake Michigan (Fig. 7.31)). Adult
Diaptomus oregonensis (Fig. 7.32) and D. ashlandi (App. F.4) were
slightly more abundant at stations nearest the Straits of Mackinac than
elsewhere in northern Lake Michigan. In contrast, D. sicilis was gener-
ally more prevalent at deep stations southwest of Beaver Island
(Fig. 7.33). Limnocalanus macrurus was found at all stations but was
generally most abundant at deeper offshore stations (App. F.4) . An
exception was a relatively large number (191/m3) at shallow Station 44.
Senecella calanoides was not observed at stations less than 120 m deep.
Diaptomus minutus and Epischura lacustris were both low in abundance and
did not exhibit any noteworthy patterns of distribution (App. F.4).
176
-------
0 8000
Figure 7.30. DISTRIBUTION AND ABUNDANCE OF CALANOID
COPEPODS IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m^.
(b) Percent composition.
177
-------
XDIflPTOMUS SPP. COPEPODIDS
DIflPTOMUS SPP. COPEPODIDS/M3
8000
Figure 7.31. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS spp.
COPEPODIDS IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
178
-------
XDIflPTOMUS OREGONENSIS
0 15
DlflPTOMUS OREGONENSIVM3
0
600
Figure 7.32. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS
OREGONENSIS IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m^.
(b) Percent composition.
179
-------
XDIflPTOMUS SICILIS
DIRPTOMUS SJCILIS/M3
0
150
Figure 7.33. DISTRIBUTION AND ABUNDANCE OF DIAPTOMUS
SICILIS IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
180
-------
Cyclopoid copepods represented only a small fraction (average 3 4%) of
total Crustacea (Fig. 7.34). Cyclops bicuspidatus thomasi was more
abundant than Mesocyclops edax at shallow stations (<30 m deep) but the
reverse was true at deep stations (App. F.4). '
Cladocera comprised an average of 46.4% of total Crustacea (Fig. 7.35).
Predominant species were Daphnia galeata mendotae and D. retrocurva,
which both represented an average of about 17% of Crustacea at all sta-
tions. These species were most prevalent at the shallowest stations
near the Straits of Mackinac and off Frankfort, Mich., and the Sturgeon
Bay Shipping Canal (Figs. 7.36 and 7.37). Eubosmina coregoni comprised
an average of 6.5% of the crustacean zooplankton and was most abundant
off the Sturgeon Bay Shipping Canal (Fig. 7.38). Likewise, Holopedium
gibberum, comprising an average of 2.9% of total Crustacea, was most
prevalent at Station 44 off of Sturgeon Bay. Otherwise, this species
did not exhibit any discernible pattern of distribution in northern Lake
Michigan (Fig. 7.39). The remaining cladocerans represented considerably
less than 1% of total Crustacea at all stations. Most species, such as
Leptodora kindtii, exhibited greatest abundance at Station 44 (App. F.4).
Chydorus sphaericus was represented by only a few individuals at
Station 28 (App. F.4).
As would be expected, species composition of crustacean zooplankton in
northern Lake Michigan was nearly identical to that observed in the
Straits region. The larger number of Mysis relicta collected in northern
Lake Michigan is undoubtedly due to the greater depths of these waters.
It is well known that a large portion of the Afysis population spends the
day off bottom in deep waters (Beeton 1960; Robertson et al. 1968) and
therefore are more readily obtainable by plankton nets.
By first inspection of these zooplankton data, it appears that the biomass
of zooplankton is higher in the Straits region than in northern Lake
Michigan. However, there may be an apparent but false reduction of num-
bers of individuals per unit volume at deeper stations simply because a
longer water column was sampled. Consequently, data calculated in terms
of percent composition of various species may be more useful for compara-
tive purposes than abundance per unit volume. An indication that this
supposition is true can be obtained by comparing two stations of similar
depth. Stations 03 in the Straits region and 26 in northern Lake Michigan
are 53 and 55 m deep, respectively. Abundance of total crustacean zoo-
plankton in the Straits (1,883/m3) was slightly higher than in northern
Lake Michigan (1,591/m3). In contrast, biomass of zooplankton was
considerably higher (6,491/m3) at a station 60 m deep in southern Lake
Michigan during September 1969 using identical methods (Gannon 1972a;.
Although these data are limited, they do suggest that there may be
substantial differences in numbers of zooplankters per unit volume in
southern and northern Lake Michigan.
Although depth-adjusted volumes of zooplankton may be comparable in
northern Lake Michigan and the Straits of Mackinac, some interesting dif-
181
-------
1- ^•T.inuiiiuyr
800
Figure 7.34. DISTRIBUTION AND ABUNDANCE OF CYCLOPOID
COPEPODS IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
182
-------
00
\
Jr 1 1 1 1
0 4000
Figure 7.35. DISTRIBUTION AND ABUNDANCE OF CLADOCERA IN
NORTHERN LAKE MICHIGAN.
(a) Numbers per m^.
(b) Percent composition.
183
-------
XDflPHNIfl GflLEflTfl MENDOTflE
0 ' ' 60
DflPHNIfl GflLEflTfl MENOOTflE/M3
2000
Figure 7.36. DISTRIBUTION AND ABUNDANCE OF DAPHNIA GALEATA
MENDOTAE IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
184
-------
XDflPHNIfl RFTROCURVfl
o"1" """"lib
DflPHNIfl RETROCURVfl/M3
1500
Figure 7.37. DISTRIBUTION A^TD ABUNDANCE OF DAPHNIA
RETROCURVA IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
185
-------
XEUBOSMINR COREGONI
6 15
EUBOSMINfl COREGONI/H3
400
Figure 7.38. DISTRIBUTION AND ABUOT>ANCE OF EUBOSMINA
COREGONI IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
186
-------
XHOLOPEDIUM GIBBERUM
HOLOPEDIUM GIBBERUM/M-
Figure 7.39. DISTRIBUTION AND ABUNDANCE OF HOLOPEDTUM
GIBBERUM IN NORTHERN LAKE MICHIGAN.
(a) Numbers per m3.
(b) Percent composition.
187
-------
ferences in relative abundance did exist in September 1973. The percent
composition of calanoid copepods was slightly higher in northern Lake
Michigan, predominantly due to greater abundance of Diaptomas sicilis.
The relative abundance of cladocerans was substantially higher in the
Straits region and in the most southerly tier of stations in Lake Michigan
than at stations in between. This pattern of distribution was due mostly
to Daphnia retrocurva, Eubosmina coregoni, and Holopedium gibberum.
It is apparent that water in the Straits of Mackinac is sufficiently
modified by the proximity of shallow, nearshore waters and by mixing with
Lake Huron water to have different physicochemical and biological
characteristics than water in northern Lake Michigan. Further data are
needed to better understand the community structure of zooplankton in
northern Lake Michigan as related to differences in water quality between
this region and the Straits of Mackinac as well as the southern portion
of Lake Michigan.
7.4 SUMMARY
Crustacean zooplankton were investigated in the Straits of Mackinac
region to: 1) provide benchmark data on species composition, distribu-
tion, and abundance; 2) analyze zooplankton community structure in rela-
tion to the interactions of Lake Michigan and Lake Huron waters; and 3)
contrast and compare zooplankton community structure between northern
Lake Michigan and the Straits of Mackinac. Fifty stations were set up
along eight transects. Samples were collected on three cruises in
August, September, and October 1973 using vertical tows of a 0.5-m diam-
eter cylinder-cone net (250 y mesh size) fitted with a Nansen throttling
mechanism.
The community of crustacean zooplankton in the Straits of Mackinac was
comprised of 29 species. Twenty-three species of Cladocera and Copepoda
were characteristic of limnetic waters, while six cladocerans were ben-
thic and littoral forms that sporadically appear in the plankton. Abun-
dance of total Crustacea at various stations during the study period
ranged from near 1,000 individuals per m3 to almost 28,000 per m3.
Distinct differences in community structure of zooplankton were readily
apparent within the Straits of Mackinac. Although species composition
was nearly identical at every station, prominent and consistent patterns
were evident in the relative proportions of species to one another in
specific sub-regions within the Straits. The relative abundance of zoo-
plankters towards Lake Michigan (west of the Straits of Mackinac) and in
the South Channel (south of Bois Blanc Island) shared many resemblances.
This region was characterized by a distinct preponderance of cladocerans,
especially Daphnia retrocurva and D. galeata mendotae. Other cladocerans,
such as Holopedium gibberumf Eubosmina coregoni, Leptodora kindtii, and
Polyphemus pediculus were also most prevalent in this region. The cala-
188
-------
noid copepods Epischura lacustris, Diaptomus oregonensis, and D. minutus
generally were characteristic of the region. In contrast, calanoid
copepods as a group were relatively most abundant in waters toward Lake
Huron, i.e., north and east of Bois Blanc Island, mainly due to copepo-
dids of Diaptomus spp., Diaptomus sicilis adults, Limnocalanus macrurus,
and Senecella calanoides. Cyclopoid copepods, predominately Cyclops
bicuspidatus thomasi, did not show any distinctive trends but appeared
somewhat more prevalent toward Lake Huron. Cladocerans, such as Bosmina
longirostris, were mainly characteristic of inshore stations in this
region.
Regions of homogeneity of zooplankton community structure, as determined
by principal component analysis, were remarkably similar to water masses
identified by cluster analysis (Sec. V). Cladocerans were relatively
most abundant in the slightly more eutrophic waters toward Lake Michigan
and in the South Channel, while calanoid copepods prevailed in the
slightly more oligotrophic waters toward Lake Huron. The community struc-
ture of crustacean zooplankton appears to be a sensitive indicator of
water quality in the Straits of Mackinac where nutrient conditions are
only subtly different.
7.5 LITERATURE CITED
Beeton, A. M. 1960. The vertical migration of Mysis relicta in Lakes
Huron and Michigan. J. Fish. Res. Board Canada 17: 517-539.
Brooks, J. L. 1957. The systematics of North American Daphnia. Mem.
Connecticut Acad. Arts and Sci., Vol. 13. 180 p.
. 1959. Cladocera, p. 587-656. In W. T. Edmondson (ed.),
Fresh-water biology, 2nd ed. New York: Wiley.
Davis, C. C. 1966. Plankton studies in the largest Great Lakes of the
world, with special reference to the St. Lawrence Great Lakes of
North America. Univ. Michigan, Great Lakes Res. Div., Pub. 14: 1-36.
Deevey, E. S., Jr. and G. B. Deevey. 1971. The American species of
Eubosmina Seligo (Crustacea, Cladocera). Limnol. Oceanogr. 16:
201-218.
Gannon, J. E. 1969. Great Lakes plankton investigations: a bibliography.
Univ. Wisconsin-Milwaukee, Center for Great Lakes Stud., Spec. Rept.
No. 7. 65 p.
1971 Two counting cells for the enumeration of zooplankton
micTo~-Crustacea. Trans. Amer. Microsc. Soc. 90: 486-490.
189
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1972a. A contribution to the ecology of zooplankton
Crustacea of Lake Michigan and Green Bay. Unpubl. Ph.D. Diss.,
Univ. Wisconsin. 257 p.
. 1972b. Effects of eutrophication and fish predation on
recent changes in zooplankton Crustacea species composition in Lake
Michigan. Trans. Amer. Microsc. Soc. 91: 82-84.
. 1974a. The ecology of Lake Michigan zooplankton—A review
with special emphasis on the Calumet Area, Appendix B, 56 p. In
R. H. Snow, Water pollution investigation: Calumet Area of Lake
Michigan. U.S. Environmental Protection Agency Rep. No. 905/9-74-
011-B, Vol. 2.
. 1974b. The crustacean zooplankton of Green Bay, Lake
Michigan. Proc. 17th Conf. Great Lakes Res., p. 28-51. Internat.
Assoc. Great Lakes Res.
. 1975. Horizontal distribution of crustacean zooplankton
along a cross-lake transect in Lake Michigan. J. Great Lakes Res. 1:
79-91.
and S. A. Gannon. 1975. Observations on the narcotization of
crustacean1 zooplankton. Crustaceana 28: 220-224.
Patalas, K. 1972. Crustacean plankton and the eutrophication of the
St. Lawrence Great Lakes. J. Fish. Res. Board Canada 29: 1451-1462.
Robertson, A., C. F. Powers, and R. F. Anderson. 1968. Direct observa-
tions on Mysis relicta from a submarine. Limnol. Oceanogr. 13:
700-702.
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. Board Canada 31: 309-317.
Welch, P. S. 1948. Limnological methods. Philadelphia: Blakiston.
381 p.
Wilson, M. S. 1959- Calanoida, p. 738-794. In W. T. Edmondson (ed.),
Fresh-water biology, 2nd ed. New York: Wiley.
Yeatman, H. C. 1959. Cyclopoida, p. 795-814. in W. T. Edmondson, (ed.),
Fresh-water biology, 2nd ed. New York: Wiley.
190
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SECTION VIII
COMPARISON OF PHYTOPLANKTON AND NUTRIENTS IN
NORTHERN LAKE MICHIGAN AND THE STRAITS OF MACKINAC
In September, after the regular sampling survey of the study area, 18
stations were sampled in northern Lake Michigan (Fig. 8.1). At these
stations, sampling procedures and methodology were the same as those that
were used on the three cruises of the Straits survey area. Comparing
data obtained in September enabled us to conclude that certain biological
conditions were unique to the Straits area. In addition, data for
September provide the basis for verification of environmental conditions
in Lake Michigan at stations removed from the influence of mixing between
Lake Michigan and Lake Huron waters. It is obvious from the data pre-
sented below that the Straits survey area did not include stations with
characteristic Lake Michigan conditions, i.e. water samples collected at
Stations 01-06, the westernmost transect, contained a mixture of Lake
Michigan and Lake Huron or Lake Superior water.
8.1 PHYSICAL-CHEMICAL CONDITIONS
Mixing apparently occurred over a broad geographic area west of the
Straits and was not uniform in one area for the three cruises. For exam-
ple, the average specific conductance at Stations 01-06 ranged from 235
to 250 ymho cm"1 on the three cruises (Table 3.1). These data also there-
fore indicate that some fraction of Lake Huron water was present at this
westernmost transect on all of the cruises.
In September the water flowing out of Lake Michigan was cooled in the
Straits of Mackinac due to the mixing with colder waters from Lake Huron.
Epilimnetic water temperatures in the main part of Lake Michigan averaged
about 17°C (Table 8.1), but in the Straits area decreased to 15°C at
Stations LM 52-54 (Table 8.1) and to temperatures as low as 14°C as the
water flowed eastward to the south of Bois Blanc Island (Table 3.1,
App. C.10 and C.ll). Evidence for mixing of colder Lake Huron water with
Lake Michigan water can also be found for data on specific conductance,
pH, silica and nitrate; there is no question therefore that mixing occurred
at least in the area extending east from Stations LM 52-54 in Lake Michigan
(Fig. 8.1) to at least Stations 24-26 in Lake Huron (Fig. 1.1).
In Lake Michigan, specific conductance at Stations LM 20-22, LM 23-25 and
LM 45-47 that are outside the area influenced by mixing in the Straits of
191
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STRAITS SURVEY
AREA-
Figure 8.1. LOCATION OF NORTHERN LAKE MICHIGAN STATIONS SAMPLED 20-23 SEPTEMBER 1973
IMMEDIATELY AFTER THE SAMPLING OF THE STRAITS SURVEY AREA. In the text stations
shown in Figure 8.1 are designated LM to distinguish them from the stations in the
Straits survey area shown in Figure 1.1.
-------
Table 8.1. AVERAGES OF ENVIRONMENTAL PARAMETERS OF EPILIMNETIC WATERS IN
LAKE MICHIGAN, SEPTEMBER 1973. Data are mean + one standard deviation.
Stations1 Temperature Specific conductance pH Secchi disc
(C) (ItrVho cm'1) (m)
LM20-222 16.8+0.93 2.676+0.038 8.578+0.029 5.00+0.50
LM23-253 17.4 + 0.22 2.673 + 0.064 8.587 + 0.081 5.00 + 0.50
1^45-47^ 16.6+0.54 2.668+0.056 8.625+0.051 4.83+0.35
LM52-545 15.0 + 0.45 2.489 + 0.020 8.539 + 0.055 5.17 + 0.58
1-66 15.4 + 0.87 2.354 + 0.127 8.514 + 0.063 3.86 + 0.79
Chlorophyll a
(mg m~3)
Silica
(mg SiO;,!-1)
Nitrate
(ugN I'1)
Total
phosphorus
(pgP I"1)
LM20-222 1.50+0.22 0.343+0.082 74.0+ 42.0 5.62+0.66
LM23-253 1.29+0.37 0.222+0.046 77.0+ 19.0 5.10+1.21
IM45-47* 1.44 + 0.35 0.217 + 0.075 50.0+ 33.0 5.07 + 0.67
LM52-545 1.45 + 0.15 0.895 + 0.109 161 + 101 5.79 + 0.58
1-66 1.73+0.70 0.951+0.162 212 + 69 4.76+0.90
Stations excepting 1-6 were sampled only in September. See Fig. 8.1.
2Average of 12 samples, depths ranging from 0-20 m.
3Average of 15 samples, depths ranging from 0-30 m.
^Average of 15 samples, depths ranging from 0-30 m.
5Average of 11 samples, depths ranging from 0-20 m.
6Data from Table 3.1.
193
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Mackinac averaged about 267 ymho cm"1 (Table 8.1). Lake Michigan waters
were diluted to the extent that at stations LM 52-54 in Lake Michigan
specific conductance averaged 249 and at Stations 01-06 in the Straits
area averaged 235 ymho cm"* (Table 3.1). It can be seen from data in
Table 3.1 that dilution of Lake Michigan water was greater in September
than during the other two months since specific conductance was least
during this month.
In the Straits area, the pH of Lake Michigan water was reduced, but only
slightly, as the result of mixing with waters from Lake Huron or Lake
Superior. In Lake Michigan at Stations LM 45-47, pH averaged greater
than 8.6 which was reduced to 8.54 at Stations LM 52-54 (Table 8.1) and
to 8.51 and 8.50 at Stations 01-06 and 13-23 in the Straits area
(Table 3.1). These differences in pH were probably real, as the measure-
ments for pH were very precise.
South of Beaver Island, the epilimnetic waters of Lake Michigan were
nearly silica-depleted, with average concentrations being as low as 0.2 mg
Si02 liter"1 (Table 8.1). In the Straits area, average concentrations
ranged from 0.9-1.0 mg Si02 liter"1 for Stations LM 52-54 in Lake Michigan
and Stations 13-23 south of Bois Blanc Island (Table 3.1). It is obvious
in comparing epilimnetic averages for the survey area (Table 3.1) that
the water needed to enrich the silica concentrations in the Straits area
was not epilimnetic water from Lake Huron, so the source of silica must
be attributable to sources in the thermocline or hypolimnion.
The waters of Lake Michigan also were depleted in nitrate nitrogen rela-
tive to waters in the Straits survey area. In Lake Michigan south of
Beaver Island, nitrate concentrations averaged less than 80 yg N03 liter"1
and as low as 50 yg NOs liter"1 at Stations LM 45-47 (Table 8.1), whereas
in the Straits survey area concentrations averaged 210 at Stations 01-06
and 240 at Stations 13-23 (Table 3.1). At Stations LM 52-54, located
west of Stations 01-06, nitrate concentrations averaged 160 yg N03 liter"1.
The large standard deviations of the mean for Stations LM 52-54 and
Stations 01-06 compared to other means for silica and nitrate provide
additional evidence that mixing occurred west of the Straits of Mackinac.
The enrichment of waters with nitrate in the Straits, as was the case with
silica, has to be attributed to mixing with metalimnetic or hypolimnetic
waters. Concentrations of nitrate and silica were greater at Stations 28-31
and Stations 07-10 (Table 3.1), where there was evidence of upwelling,
than were found at stations characterized by epilimnetic waters.
Total phosphorus concentrations in the Straits survey area seemed to be
affected least by the mixing of Lake Huron and Lake Michigan waters.
Since Lake Michigan concentrations (Table 8.1) were larger than those for
Lake Huron (Stations 24-31 and 40-45, Table 3.1), the result expected from
mixing would be lower concentrations in the Straits survey area than in
Lake Michigan. A slightly lower concentration was found at Stations 01-06,
but the concentration at Stations LM 52-54 averaged greater than the Lake
Michigan stations. Since the variance in the averages was large, these
differences in the averages may not be significant. The data do suggest
that there may be an enrichment of phosphorus in the Straits area; if such
194
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an enrichment process existed, it might be attributable to biological
factors or possibly to morphometric effects.
In September, Secchi disc transparency seemed to be greater in Lake
Michigan (Table 8.1) than in the Straits area at Stations 01-06 and Sta-
tions 13-23 (Table 3.1); however, the differences were small. In Lake
Huron, Secchi disc transparency was obviously greater than in Lake
Michigan. These data and the data for chlorophyll suggest that standing
crops in the Straits area were greater than either in Lake Michigan or
Lake Huron. These differences, if real, were small since average chloro-
phyll concentrations ranged from 1.21 to 1.78 mg chlorophyll a liter~1
(Tables 3.1 and 8.1).
8.2 PHYTOPLANKTON
Data on the distribution of phytoplankton for the three cruises have been
summarized in relation to temperature-specific conductance regions and in
relation to results of ordination analysis. Other data are presented in
Section VI, summarizing abundance and distribution of the 289 phytoplank-
ton species collected as part of the study.
It is obvious that the phytoplankton community associated with Lake
Michigan water in August and September (Tables 8.2 and 8.3) was primarily
green and blue-green algae. In these two months, the communities unique
to Lake Michigan waters did not contain diatoms due to the effects of
silica limitation. Stations 40-48 were not sampled in August, so the
community associated with regions typical of Lake Huron were not sampled;
however, one station, 25, with a community of three diatoms and one
cryptomonad, was identified from ordination analysis. Cyclotella comta
and C. operculata were the two diatoms in the community identified in
Lake Huron samples from September.
Hypolimnetic samples from August and September were characterized with
ordination analysis as diatom communities. The August community consisted
of Cyclotella ocellata and C. stelligera, and C. ocellata was also pres-
ent in the September community with Shizosolenia eriensis replacing
C. stelligera. These hypolimnetic communities were also identified for
both months from cold regions along the northern shore, which is evidence
of upwelling (Tables 8.2 and 8.3).
In October, diatoms as well as blue-green and green algae were identified
in the phytoplankton community found in the waters of Lake Michigan
(Table 8.4). Water flowing from the St. Marys River was characterized
by a community in which Asterionella fornosa was dominant while the com-
munity in Lake Huron was primarily diatoms and cryptomonads. As is
September, the hypolimnetic community consisted of C. ocellata and R.
eriensis.
The influence of water transport from Lake Michigan and mixing of Lake
Michigan and Lake Huron water in the Straits area on the distribution and
abundance of phytoplankton can be inferred from data collected in
195
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Table 8.2. SUMMARY OF RELATIONSHIPS BETWEEN T-C PATTERNS AND PHYTO-
PLANKTON COMMUNITY PATTERNS OF AUGUST SAMPLES.
Region based
on T-C
Location and
description
Region based on
phytoplankton
communities
Associated
community
(Figs. 6.36b
and 6.38b)
Community
description
Lake Michigan and south
of Bols Blanc Island;
5-m depth; warm; high
conductivity
Surface along northern
shore; cold; apparently
upwelled
Single station (#25) in
southeastern corner;
low conductivity; water
probably from Lake Huron
but possibly from the
St. Marys River
Hypolimnion of
northeastern stations
Green and blue-green algae
Two diatoms:
Cyclotella ocellata and
Cyclotella stelligera
Three diatoms, one cryptomonad
Two diatoms:
Cyclotella .ocellata and
Cyclotella stelligera
Table 8.3. SUMMARY OF RELATIONSHIPS BETWEEN T-C PATTERNS AND PHYTO-
PLANKTON COMMUNITY PATTERNS OF SEPTEMBER SAMPLES.
Region based
on T-C
Location and
description
Region based on
phytoplankton
communities
Associated
community
(Figs. 6.36b
and 6.38b)
Community
description
Lake Michigan and south
of Bois Blanc Island;
5-m depth; warm, high
conductivity
Surface along northern
shore; cold
US Southeastern section of
survey area
Mouth of St. Marys River;
5-m depth; warm, low
conductivity
Hypolimnion of
northeastern section
mainly green and blue-green
algae
Two diatoms:
Cyclotella ocellata and
Rhizosolenia eriensis
Two diatoms:
Cyclotella coirtta and
Cyclotella operculata
Two diatoms:
Cyclotella ocellata and
Rhizosolenia eriensis
196
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Table 8.4. SUMMARY OF RELATIONSHIPS BETWEEN TEMPERATURE-CONDUCTIVI-
TY PATTERNS AND PHYTOPLANKTON COMMUNITY PATTERNS OF OCTOBER SAMPLES.
Region based
on T-C
Associated
Region based on community
Location and phytoplankton (Figs. 6.36b
description communities and 6.38b)
Lake Michigan and south
of Bois Blanc Island;
5-m depth; warm; high
conductivity
Mouth of St. Marys
River; 5-m depth;
warm; very low
conductivity
Eastern section of
survey area; 5-m; cold,
moderate conductivity
Hypolimnion of
northeastern section
Community
description
mixture of blue-greens,
greens, and diatoms
Asterionella formosa
relatively abundant; very low
total cell density
Primarily diatoms and
cryptomonads ; very low
densities of greens and
blue-greens
Two diatoms:
Cyclotella ocellata and
Rhizosolenia eriensis
September. The distribution and abundance of nine species were investi-
gated from samples collected in the Straits survey area plus the stations
sampled in Lake Michigan (Fig. 8.1). Data for the comparisons among
these phytoplankton were plotted as averages. For the Straits survey
area, 5-m samples were averaged for the regions plotted; for Lake Michigan
(Fig. 8.1), samples from 0, 5, 10 and 20 m were averaged for each station
since there was no evidence of thermal stratification.
Two species of blue-green algae were found in fairly uniform abundances
at all stations sampled in Lake Michigan. Both species, Anacystis incerta
and A. thermalis, seemed to be transported through the Straits south of
Bois Blanc Island into Lake Huron (Figs. 8.2 and 8.3), a pattern identi-
fied previously in the Straits survey area (Table 8.3, Fig. 6.34). These
species were not abundant outside of region A (Fig. 6.34), indicating
that transport was the main mechanism that could be used to explain the
distribution. None of the remaining seven species had distributions of
this type.
Five species of diatoms were found in the Straits survey area and at sta-
tions LM 52-54 in Lake Michigan. In general, these species were found in
only limited abundance at other stations in Lake Michigan, and therefore
seemed to be favored by conditions in the Straits area or in the area
where waters from the two lakes mixed. Three of the species, Fragilaria
crotonensis, Cyclotella stelligera and C. comta, seemed to be equally
abundant at all stations including those in Lake Michigan, Lake Huron and
at the mouth of the St. Marys River (Figs. 8-4-8.6), although C. comta
and F. crotonensis seemed to be more abundant in Lake Huron. Reasons for
the ubiquitous distribution are not apparent. The other two species of
diatoms, Cyclotella ndchiganiana and Asterionella formosa, were most
197
-------
RNRCYSTIS INCERTR CELLS/ML
i 1 1 1
0 6000
Figure 8.2. DISTRIBUTION OF ANACYSTIS INCERTA.
RNflCYSTIS THERMRLIS CELLS/ML
^ \-
0 300
Figure 8.3. DISTRIBUTION OF ANACYSTIS THERMALIS.
198
-------
FRflGILRRIR CROTONENSIS CELLS/ML
i 1 1 1
0 150
Figure 8.4. DISTRIBUTION OF FRAGILARIA CROTONENSIS.
CYCLOTELLfl STELLIGERfl CELLS/ML
0 150
Figure 8.5. DISTRIBUTION OF CYCLOTELLA STELLIGERA.
199
-------
CYCLOTELLF) COMTfl CELLS/ML
80
Figure 8.6. DISTRIBUTION OF CYCLOTELLA COMTA.
abundant in Lake Michigan and south and east of Bois Blanc Island
(Figs. 8.7 and 8.8) or in region M (Table 8.3).
Finally, the distribution of two species of Cyclotella, C. ocellata and
C. operculata (Figs. 8.9 and 8.10), seemed to be restricted mainly to the
stations east of Bois Blanc Island. C. ocellata was characteristic of the
hypolimnetic community (Table 8.3)—the fact that this species was not
found west of the Straits in relatively large abundances indicates either
that hypolimnetic water was not transported to the west or that this
species did not thrive in the mixed water.
8.3 SUMMARY
Many of the results obtained as part of the study of the Straits area and
northern Lake Michigan can be explained as being due either to mixing of
water transported from Lake Michigan into Lake Huron or as the result of
transport of Lake Huron water westward into Lake Michigan.
The general pattern of surface water transport from Lake Michigan, as
delineated by our results, was from Lake Michigan through the Straits of
Mackinac and then south of Bois Blanc Island to Lake Huron. This trans-
port appeared to be similar when the water was stratified thermally in
August, as well as in October when there was no thermal stratification
200
-------
CTCLOTELLfl MICHIGflNIflNfl CELLS/ML
0 80
Figure 8.7. DISTRIBUTION OF CYCLOTELLA MICHIGANIANA.
flSTERIONELLfl FORMOSR CELLS/ML
0 80
Figure 8.8. DISTRIBUTION OF ASTERIONELLA FORMOSA.
201
-------
CTCLOTELLfl OCELLflTfl CELLS/ML
0 200
Figure 8.9. DISTRIBUTION OF CYCLOTELLA OCELLATA.
CTCLOTELLR OPERCULflTfi CELLS/ML
i 1 1-
0 15
Figure 8.10. DISTRIBUTION OF CYCLOTELLA OPERCULATA.
202
-------
south of Bois Blanc Island.
Transport of Lake Huron water to Lake Michigan when the lakes were not
stratified thermally appeared to be complex, being controlled by the
oscillatory flow between the two lakes. Under thermally stratified condi-
tions, Lake Huron water flowed west under the epilimnion, eventually being
entrained and mixed with Lake Michigan water west of the Straits. Based
on morphometry, the subsurface flow was north of Bois Blanc Island along
the northeast side of Mackinac Island, then south between Mackinac Island
and Rabbit's Back Peak and finally west through the Straits into Lake
Michigan; water can be transported in this pattern in a well-defined chan-
nel at depths of 40 m.
203
-------
APPENDIX A. Physical and chemical data collected in the vicinity of the Straits of Mackinac, 1973
Appendix A.I Cruise 1, August 1973
STA
1
1
1
2
2
2
2
2
3
3
3
3
3
3
3
4
0 »
° 4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
8
8
9
9
9
9
9
9
9
DEP
1
0
5
10
0
5
10
15
20
0
c
10
15
20
25
30
0
5
10
15
20
C
5
10
0
5
10
0
5
10
0
5
10
15
20
0
5
10
15
20
25
30
SAMP
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
28
29
30
31
32
33
34
39
40
41
42
43
44
45
SEC
m
4.5
4.5
4.5
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.1
5. 1
5.1
5. 1
5.1
5.0
5.0
5.0
5.5
5.5
5.5
6.2
6.2
6.2
6.0
6.0
6.0
6.0
6.0
5.9
r>.9
5.9
5.9
5.9
5.9
5.9
TEMP
°C
21.8
21.8
21.5
21.1
21.1
21. 1
21.1
18.0
21.0
21.0
21.0
21.0
15.8
12.0
10.8
21.0
21.0
21.0
20.0
13.0
21.0
21.0
21.0
21 .4
21.4
20.0
17.0
17.0
15.0
20.2
20.2
16.0
12.2
11.0
21.0
20.2
19.5
1 3.5
9.0
7.5
7. 5
pn
8.70
8.68
8.68
8.62
8.60
8.60
9.52
8.52
8.67
8.68
8.66
8.66
8.53
8.42
8.14
8.69
8.69
8.67
8.62
8.32
8.70
8.69
8.58
8.70
8.71
8.70
8.58
8.52
8.43
8.66
8.66
8.40
8.11
8.10
8.67
8.67
8.68
8.52
3.22
8.02
7.96
COND
~*mho/cni
2.29
2.55
2.53
2.50
2.55
2.55
2.55
2.55
2.50
2.50
2.50
2.50
2.40
2.35
2.16
2.52
2.49
2.51
2.46
2.24
2.50
2.50
2.43
2.50
2.50
2.49
2.32
2.27
2. 19
2. «4
2.45
2. 07
2.05
2.05
2.47
2."^
2.Uu
2.14
2.2C
2.16
CHL
mg/n:
1.63
1.60
1.64
1.55
1.52
1.49
1.55
1.52
1.58
1.74
1.56
1.74
1.54
1.31
1.46
1.57
1.42
1.30
1.39
1.60
1.29
1.34
1.56
1.41
1.32
1.39
1.31
1.35
1.40
1.18
1.22
1.87
1.60
1.73
1.10
1.29
1.41
1.79
l.tiO
.97
.89
PHAE
fraction
.09
.11
.09
.08
.11
.11
. 13
.14
.03
.10
.07
.07
.19
.18
.24
.06
.13
.15
.18
.15
.10
.11
.18
.13
.15
.15
.11
. 11
.10
.15
.20
.11
.21
.13
. 10
.10
. 11
. 13
. 18
.27
.35
SI02
«gSi02/l
. 44
.45
.45
.44
.65
.44
.45
.50
.43
.43
.43
.44
.80
1.14
1.42
.49
.48
.50
.60
1.22
.52
.53
.76
.58
.59
.60
.84
.91
.99
.63
.63
1. 14
1.31
1.39
.69
.59
.64
.97
1.38
1.71
1.79
H03
«gN/n3
117.4
125.9
125.9
145.9
151.6
157.3
157.3
147.3
1H4.5
145.9
138.8
158.7
200.1
224.3
265.7
146.2
132.7
135.4
150.3
246.4
134.1
131.3
171.9
130.0
127.3
130.0
165.9
197.6
221.6
144.3
146.8
246.9
278.5
289.9
161.9
145.4
149.2
218.8
279.6
298.5
321.3
TP04
•gP/«*
6.17
5.10
5.86
6.57
5.07
4.55
4.46
5.05
4.26
4.61
3.83
5.40
5.30
4.57
3.39
4.47
5.60
4.45
6.11
3.69
3.77
4.16
4.28
3.14
3.46
3.48
3.68
6.35
4.61
2.93
2.89
3.88
5.55
4.52
2.92
2.92
3.49
3.61
4.02
4.07
SP04
•9P/»3
2.49
3.52
5.24
2.69
2.67
2.69
2.65
3.65
2. 14
2.36
2.97
2.61
2.20
2.98
1.86
4.49
2.42
2.16
3.33
5.23
3.38
3.53
3.16
1.95
1.98
1.74
2.03
2.44
1.70
1.67
1.60
1.27
1.63
1.68
1.90
1.40
1.77
2.22
2.04
2.11
2.45
S04
•gSO4/l
15.94
16.71
17.75
17.81
18.29
15.80
17.97
17.18
16.11
16.02
16.22
15.43
15.20
14.69
12.91
16.21
16.69
16.89
15.96
13.19
16.35
16.55
15. t9
16.52
16.72
16.35
14.85
13.91
13.41
15.86
14.79
12.30
12.07
11.99
15.44
15.49
15.83
12.92
12.13
11.90
11.95
Cl
•gCl/1
7.7.9
7.71
7.78
7,59
7.66
6.78
7 ..6.8
7.68
7.48
7.36
7.51
6,78
6.97
6.58
S.64
7.40
7.51
7 .51
7.23
5,83
7,»5
7.41
6.80
7. ,32
7.43
7.38
6.39
6.12
5.78
7,17
7.13
5.43
5.23
5.19
7.30
7.25
7.09
5.62
5.35
5.23
5.22
-------
App. A.I cont.
STi DIP SAMP
M
10
10
10
10
10
11
11
11
11
11
11
12
12
12
13
13
13
14
0 1"
S 14
14
m
15
15
15
15
15
16
16
16
17
17
17
18
18
0
5
10
15
20
0
5
10
15
20
25
0
c
10
0
ft
10
0
K
1 0
15
20
0
5
1C
15
20
0
5
15
0
4
8
C
c
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
SEC
m
6.5
6.5
6.5
6.5
6.5
6.5
6.0
6.0
6.0
5.4
5.4
5.4.
6.0
6.0
6.0
6.0
6.0
5.8
5.8
5.8
.5.8
5.8
4.7
4.7
4.7
5.2
5.2
5.2
6.C
6.0
TEKP
°C
21.1
19.5
19.4
18.0
8.0
21.5
20.6
18.0
13.2
10.8
10.0
21.0
20.6
19.2
22.0
22.0
22.0
21.5
21.5
21.5
20.0
12.0
21.5
21.5
20.0
17.5
12.0
21.5
21.5
19.0
21.8
21.8
20.9
22. r-
21.8
PH
8.62
8.65
8.64
8.59
8.26
8.70
8.70
8.60
8.43
8.24
8. 10
8.67
8.68
8.67
8.65
8.65
8.64
8.64
8.66
8.65
8.59
8.17
8.64
8.65
8.63
8.51
8.26
8.65
8.66
8.60
8.67
8.67
8.67
8.67
8.67
CCND
— * mho/cm
2.39
2.39
2.39
2.31
2.15
2.30
2.?0
2.31
2.07
2.10
2.06
2.36
2.3.8
2.37
2.46
2.46
2.46
2.45
2.46
2.47
2.43
2.24
2.46
2.46
2.45
2.40
2.25
2.U9
2.49
2.44
2.47
2.48
2.49
2.45
2.44
CHi
ag/rn3
.94
1.19
1.54
1.54
1.10
1.00
1.13
1.45
1.83
1.75
1.53
1.12
1.35
1.37
1.39
1.20
1.43
1.01
1.13
1.32
1.52
1.08
1.03
1.07
1.34
.99
1.41
1.28
1.25
1.38
.98
1.26
1.39
.88
1.04
PHAE
fraction
.19
.23
.06
.21
.25
.21
. 17
.18
.14
.06
.18
.12
.12
.15
.10
. 19
.15
.15
. 14
-.06
.21
.25
.16
.18
.23
.25
.24
.18
. 18
.12
.12
. 15
.23
.14
.21
5102
mgSi02/l
.74
.65
.64
.75
1.54
.61
.59
.67
1.02
1.34
1.48
.59
.58
.62
.56
.57
.49
.57
.57
.53
.62
1.21
.53
.54
.58
.76
1.15
.51
.51
.64
.55
.54
.57
.53
.53
N03
ngU/n*
169.3
156.6
157.8
176.8
279.4
162.8
155.1
170.3
237.4
276.6
288.0
146.9
144.0
149.2
192.7
148.0
177.3"
218.8
191.6
153.6
158.7
378.8
159.4
169.8
190.9
203.5
304.6
170.2
171.6
178.4
164.3
157.6
194.1
159.0
149.6
TPO4
«gP/«3
2.99
2.57
4.09
3.67
3.89
2.69
3.03
3.77
3.59
3.59
3.08
2.48
2.71
5.01
4.42
4.38
5.28
4.52
4.70
4.68
4.39
5.32
5.46
4.76
4.63
4.47
4.63
6.93
4.21
5.18
4.10
3.37
3.64
3.50
4.38
SP04
agP/n*
1.78
2.43
1.85
1.97
1.70
1.64
1.44
2.29
1.80
2.27
1.63
1.74
1.65
3.36
4.17
3.45
3.59
3.46
3.57
3.38
3.49
5.32
4.01
3.14
3.64
2.83
3.24
3.46
3.74
2.77
2.56
2.59
2.99
2.89
S04
»gS04/l
13.56
15.17
15.37
13.73
12.37
14.13
14.18
13.81
12.46
11.66
12.28
14.60
15.36
14.85
15.48
15.^5
16.15
15.50
15.70
15.47
15.24
13.18
15.61
15.55
13.32
15.01
12.65
15.96
16.16
15.29
15.76
15.97
14.82
15.97
15.77
Cl
•gci/i
6.54
6.98
7..02
6.10
5.35
6.64
6.64
6.60
5,79
5.4.0
5.»29
7.04
7.11
7,07
7.29
7.44
7.«t4
7.17
7.36
7.31
6,37
6»07
7.4.2
7.34
6.06
6.85
5.35
7.48
7.33
7.10
7.32
7.35
6.67
7.23
7.12
-------
App. A.I cont.
;TA
19
19
19
19
19
20
20
20
21
21
21
22
22
22
22
23
23
23
24
24
24
24
25
25
25
25
25
26
26
26
26
26
26
26
27
27
27
27
27
27
27
27
27
27
DEP
M
0
5
10
15
20
0
5
10
0
c
10
0
5
10
15
0
C
10
0
c
10
15
0
5
10
15
25
0
5
10
15
20
25
30
0
R
10
15
20
25
30
35
HO
49
SAMP
8U
35
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
1C3
105
104
106
107
108
109
110
111
112
113
114
115
H6
117
118
110
120
121
12'
123
124
125
126
127
SEC
tn
5.6
5.6
5.6
5.6
5.6
6.0
6.0
6.0
6. 1
6.1
6.1
5.3
5.3
5.3
5.3
5.7
5.7
5.7
7.6
7.6
7.6
7.6
8.2
8.2
3.2
8.2
8.2
8.6
8.fi
8.6
8.6
8.6
8.6
8.6
7.9
7.9
7.9
7.9
7. "
7.9
7.9
7.9
7.9
7.9
TEMP
°C
22.0
21.4
20.8
17.5
13.8
22.0
22.0
21.5
21.5
20.0
18. C
21.5
21.0
20.0
16.0
22.0
21.0
20.5
22,1
22.0
21.2
15.0
22.0
20.9
2.1.0
13.0
8.5
22.5
21. *
20.8
13.0
10.0
8.5
7.5
23.0
21.5
21.0
17.0
1 1.5
9.5
8.5
7.5
6.5
5.9
PH
8.67
8.68
8.65
8.56
8.31
8.66
8.65
8.66
8.67
8.68
8.57
8.68
8.69
8.65
8.45
8.67
8.58
8.66
8.67
8.68
8.69
8.50
8.65
8.65
8.64
8.42
7.95
3. 6H
a. 63
8.66
8. 41
8. 11
7.'J2
7.83
3.64
8.67
8.&7
8.43
8.21
8.05
7.93
7.89
7.81
7.82
COHD
-»mhc/cm
2.45
2.48
2.34
2.34
2.2*
2.40
2.40
2.44
2.41
2.39
2.23
2.44
2.44
2.32
2.20
2,50
2,47
2.46
2.22
2.14
2.01
2.17
2.00
1 .96
1.96
2.10
2.11
2.12
2.16
2.03
2.02
2.C'3
2.13
2.18
2.19
2.20
2.22
2.08
2.07
2.06
2.11
2.13
2.16
2.20
CHL
mg/m3
1. 11
1.46
1.60
1.54
1.51
1.15
.97
1. 19
1.00
1.13
1.58
1. 10
1.19
1,45
1.92
1.11
1.21
1.52
1.04
1.11
1.12
1.68
1.06
1.22
1.33
1.79
1.39
.98
.96
1.22
1.47
1.60
1.61
1.25
1.12
1.07
1.17
1.69
1.57
1.24
.°6
.77
.75
.64
PHA~
fraction
. 18
.22
.19
...19
.23
.18
.20
.20
.17
.17
. 19
. 19
.19
.21
.19
.21
. 17
.20
.14
.17
. 10
.19
.15
. 10
.16
.16
.24
.37
.16
. 21
.13
.15
. 19
.28
-.03
.09
.21
.18
.21
.26
.35
. 30
.41
.48
SI02
mgSi02/l
.53
.55
.60
.40
1.12
.58
.57
.55
.57
.55
.75
.54
.53
.62
.94
1.09
.96
.61
.69
.65
.65
.93
.89
.70
.67
.93
1.69
.73
.79
.64
.96
1.44
1.72
1.87
.65
.61
.60
.98
1.21
1.44
1 .54
1.59
1.64
1.78
N03
•gN/ffl3
156.4
164.5
180.8
184.9
186.3
176.8
175.5
162.0
191.3
161,5
196.8
146.9
163.4
169.6
230.5
108.6
152.6
181.5
212.4
212.4
227.4
249.4
305.9
214.0
253.7
255.0
341.4
204.7
212.9
249.9
303.3
334.8
354.0
200.4
187.1
207.0
234,8
285.1
309.0
319.6
326. 1
324.8
306.2
TP04
aqp/ns
4.23
3.73
4.54
3.68
4. 19
3.95
3.43
3.62
3.76
3.67
4.12
*
4.00
5.38
3.90
3.94
3.83
3.49
3.46
1.48
1.15
.87
2.31
.96
1.03
1.60
1.56
1.56
1.61
1.15
1.44
1.37
1.38
1.68
2.58
1.84
1.70
2.57
2.81
9.44
4.85
3. 16
3.04
2.30
3.91
SP04
•gp/«3
2.70
2.87
2.64
2.82
3.19
3.20
2.70
3.10
3.11
2.90
2.85
2.77
2.70
3.20
2.75
3.00
2.76
2.61
.68
.43
.60
.65
.65
.50
.16
.48
.72
.42
.06
.30
.45
3.50
1.06
1.16
1.06
1.25
1.74
2.07
1.90
1.31
son
•gS04/l
15.71
16.18
14.90
14.56
13.96
15.38
15.04
15.52
15.18
14.85
13.64
15.39
15.73
15.12
13.57
14.05
15.20
16.08
13.85
13.52
12.71
12.91
12.51
11.91
12.11
12.18
11.98
12.05
10.50
10.30
11.72
10.98
11.99
11.93
13.21
11.12
13.48
12.20
11.73
11.13
11.87
11.67
11.74
11.81
Cl
• gd/1
7.23
7.30
6.81
6.5.8
6.24
7..1P
6.99
7.17
6,. 98
6.68
6,07
7. Q.I
7,08
6.66
5«a«
6.17
6.96
7.10
6.19
5.90
5.54
5.76
5., 4 7
5.37
5.23
5*46
5.20
5.25
3.19
3^21
5.35
4,39
5. ,4 3.
S...3.7
6*27
6.5U
6,,47
5^62
5,. 33
<»»78
5.. 31
5.*3
5-51
5.70
-------
App. A.I cont.
STA DEP SAMP
H
28 0 128
28 5 129
28 10 130
28 15 131
28 20 132
28 25 133
28 30 134
28 40 135
28 50 136
28 60 137
29 0 138
29 5 139
29 10 140
29 15 141
29 20 142
29 25 143
29 30 144
29 40 145
29 50 146
29 60 147
30 0 148
30 5 149
30 10 150
30 IE 151
30 20 152
30 25 153
30 30 154
30 35 155
30 40 155
31 0 157
31 5 150
31 10 159
31 15 16C
31 ?0 161
32 0 162
32 5 163
32 10 164
32 20 165
33 0 166
33 5 167
33 10 169
33 TO 169
SEC
01
7. 1
7.1
7.1
7.1
7.1
7.1
7.1
7. 1
7.1
7. 1
7.9
7.9
7.9
7.9
7.9
7.9
7.9
7.9
7.9
7.9
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
6.5
3.5
3.5
Q.5
9.5
K.O
6.0
6 . C
'..I
6.2
6.2
6.2
6.2
TEKP
•c
21.3
21.2
20.0
16.8
1 1.5
9.5
8.5
7.5
6.4
5.9
21.5
21.0
2C.5
15.5
9.0
7.0
6.0
5.0
4.5
4.5
21.2
21.2
17.0
13.0
13.'4
8.0
7.8
7.0
6.5
2 v.1
1-3.0
13.6
11.*
1 1.0
1 9 . '•>
1^.1
1 5.0
10.4
20. 3
20.3
15.0
10.2
PH
8.62
8.64
8.64
8.49
8.25
8. 11
8.01
7.93
7.78
7.30
8.61
8.66
8.64
8.51
8.23
8.15
8.03
7.95
7.84
7.77
8.53
8.63
8. 54
8.37
8.22
8.06
3.02
8.00
7.97
8.57
8.55
8.43
8.25
8. 19
3 . f. -6
a. 66
fi.sri
8. 30
8.67
8.65
3.56
8.36
COND
2.22
2.25
2.20
2.06
2.05
2.06
2.10
2.15
2.22
2.22
2.26
2.23
2.24
2.11
2.02
2.09
2.13
2.17
2.1S
2.20
2.23
2.2 )
2.04
1 .9u
1.97
2. 10
2.m
1. 16
2.1 s
1 .99
2.0)
1 .94
1.96
2. CO
2.23
2 . 2 ')
2.0"
1.96
2.25
2.2 i
2.15
2.06
CHL
1.04
1.17
1.34
1.74
1.28
1.27
1.05
.66
.53
.45
1.45
1.31
1.37
1.87
1.26
1.02
.82
.57
.39
.33
.84
1.06
1.61
1. 42
1.23
1.00
.79
.83
.76
.82
1. 1.6
1.19
1.40
1. 39
.78
1.2b
1.78
1.61
1.2.9
1.47
1 . ">3
1.52
PHAE
fraction
.11
.04
.13
.14
.21
.20
.28
.41
.41
.53
.06
.13
. 15
.19
.20
.22
.33
.44
. 54
.69
.16
. 14
.09
.13
. 19
.31
. 40
.38
.42
.11
. 11
.13
. 16
.20
.13
.1 ?
.06
.18
.17
. 16
.10
.21
SIO2
mgSi.02/1
.66
.60
.62
.81
1.28
1.37
1.58
1.45
1.56
.66
.59
.61
.83
1.15
1.25
1.35
1.51
1.70
1.96
.69
.71
.86
1.09
1. 35
1.55
1.61
1.67
1.70
.97
.86
1.06
1.27
1.31
.36
.43
1.05
1.59
.74
.76
.85
1.40
NO3
agN/»3
183.5
194.1
228.6
229.9
280.2
292.1
321.3
323.9
326.5
333.1
190.3
177.1
194.2
225.8
285.2
323.4
315.5
329.9
331.2
364.2
205. 1
199.8
240.7
282.9
304.0
338.2
346. 1
332.9
344.7
211.9
244.9
275.2
301.5
313.4
161.3
188.4
259.7
316.8
186.8
185.3
228.0
313.7
TPO«
ngP/B3
2.70
3.98
2.60
2.93
3.64
2.95
2.22
1.28
2.59
2.65
2.29
2.79
1.70
2.71
2.62
1.53
1.39
1.43
2.86
2. 18
4.99
2.18
2.06
1.78
2.80
2.64
2.35
2.24
2.69
3.94
2.51
3.44
4.82
3.11
2.60
4.85
3.84
cj. 34
2.87
3.08
4.68
5.42
SPO4
ngP/m*
2.44
2.32
2.01
1.52
1.16
1.49
1.16
1.84
.48
.54
1.08
1.00
.57
1.90
.80
.67
.38
.69
1.23
.49
.69
1.14
.25
1.01
.63
.86
1 .36
1 .52
.89
2.70
1.40
1.19
1.50
2.34
2.45
1.62
1.49
1.74
2.27
1.44
2.28
1.59
S04
•gS04/l
13.36
14.11
13.10
11.47
10.68
11.50
11.44
11.53
11.62
11.85
13.55
14.07
13.58
12.50
11.27
11.79
12.17
11,53
11.91
10.83
13.11
12.76
11.83
11.18
11.42
11.80
10.72
11.83
11.77
12.15
11.51
11.01
11.39
11.19
12.89
12.24
10.43
11.39
12.21
12.74
11.66
11.31
C*.
•gci/l
6.64.
6.76
6. HI
5.73
4.54
5.J3
5. .13
5,21
5*32
5,32
£.55
6.48
6.37
5.51
4.88
5,00
5.01
5.09
5.25
4.29
6.Q4
5.94
5,34
5.00
5.. 15
4.45
5.38
5.27
5.27
5.12
4.60
4. .79
4.83
5.98
5.68
3.98
4.83
5.72
6.13
5.57
4.98
-------
App. A.I cont.
NJ
O
oo
STA
34
34
34
34
34
34
34
34
35
35
35
35
35
35
35
35
36
36
36
36
36
36
36
36
36
36
37
37
37
37
37
37
37
37
37
37
111
111
111
111
111
111
112
112
112
DEP
M
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
35
0
5
10
15
20
25
30
•3 c
40
45
0
5
1C
15
20
25
3C
35
40
45
0
5
10
15
20
25
0
5
10
SAMP
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
188
189
190
191
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
2C8
2,12
213
214
215
216
217
209
210
211
SEC
n
7-.0
7.0
7.0.
7.0
7.0
7.0
7.C
7.0
7.0
7.0
7.C
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.C
7.0
7.C
7.0
7.0
7.T
5.7
5.7
5.7
5.7
5.7
5.7
5.8
5.8
5*8
TEMP
•c
21.2
21.0
13.6
1 1.2
1C.O
9.0
8.0
7.5
20. 9
20.0
14.0
1 1.0
9.5
8.6
8.2
7.5
20.6
20.6
16.0
10.9
9.8
9.0
8.4
7.8
7.0
6.5
20.0
20.0
13.0
10.fi
9.8
9.0
8.1
7.5
7.0
6.5
21. n
20.5
20.0
13.0
9.9
8.4
22.0
21.9
2V.O
PH
8.66
8.67
8.54
8. 36
8.28
8. 22
8.21
8.15
8.64
8.62
8.41
8.34
8.25
8.16
8.08
8.07
8.63
8.67
8.60
8.39
8.25
8.15
8.08
8.01
7.99
7.93
8.65
8.65
8.61
8.34
8.13
8.05
7.94
7.89
7.84
7.82
8.65
8. £ 4
8. 6^
8.45
8.11
7.97
8.64
8.66
8.56
com
-*raho/cm
2.2S
2.15
2.15
2.05
2.10
2.12
2.14
2.00
2.36
2.30
2.04
2.03
2.10
2.10
2.16
2.20
2.33
2.35
2.25
2.06
2.10
2.12
2.16
2.16
2.16
2.21
2.26
2.32
2.25
2.06
2.12
2 ". 1 6
2.17
2.16
2.17
2.16
2.46
2.45
2.39
2.24
2.08
2.13
2.50
2.50
2.47
C!U
mg/a
.25
.08
.81
.58
.30
.38
.86
.81
1.14
1.39
1.81
1.61
1.54
1.05
.77
.75
1.22
1.20
1.72
1.65
1.35
1.17
.86
.74
.62
.64
1.24
1.33
1.31
1.51
1. 13
1.00
.70
.87
.76
.62
1. 12
1.36
1.37
1.71
1.52
1.34
1.20
1.35
.41
PHAE
fraction
.08
.07
. 14
.15
.21
. 17
.33
.34
.14
.11
.11
.11
.13
.25
.35
.37
.13
.12
.09
.16
.16
.25
.35
.36
.37
.42
.14
. 14
.13
.20
.19
.30
.43
.25
.41
.45
.21
.14
.15
.18
.18
.24
.07
.19
.19
SI02
agSi02/l
.69
. 68
.90
1.26
1.37
1.43
1.57
1.60
.66
.69
1.00
1.19
1.34
1.47
1.59
1.60
.70
.63
.76
1.09
1.32
1,49
1.51
1.47
1.55
1.82
.65
.63
.75
1.20
1.44
1.53
1.65
1.83
118J3
1.93
.53
.54
.62
.89
1.40
1.53
.50
.50
.52
N03
ng N/B a
187.9
18C.7
250.6
313.4
343.3
346.1
354.6
364.4
194.4
187.2
271.4
309.8
335.5
349.6
353.8
355.1
162.5
163.8
198.9
281.4
344.9
327.3
334.0
335.3
335.3
342.0
187.8
174.2
201.2
289.1
321.5
328.2
337.7
353.8
355.2
351.1
132.0
141.4
136.4
207.6
274.9
294.8
122.1
144.7
135.7
TP04
BgP/»3
2.61
3.49
3.32
4.78
3.00
2.52
2.66
2.88
2.61
2.68
2.94
3.18
2.79
Z.07
4.70
1.95
2.33
2.13
2.01
2.39
2.01
1.98
2.15
3.00
2.62
2.45
2.28
3.09
2.17
2.59
2.62
2.26
2.09
2.64
2.71
2.57
2.40
2.80
3.18
2.05
2.22
2.23
2.49
2.59
SP04
ngP/B*
1.69
1.99
1.86
1.65
2.57
1.57
1.83
1.52
1.92
1.80
1.51
1.39
1.32
2.07
1. 19
1.50
1.05
1.05
1.02
1.11
1.20
.61
.77
1.01
.89
1.74
1.74
1.45
1.14
1.82
.81
1.47
1.04
1.25
1. 18
1.16
1.30
1.C1
1.34
.99
1.19
.79
1.27
1.06
1.60
S04
•gSO4/l
12.86
13.83
12.01
9.90
11.16
11.11
11.78
11.14
14.15
13.95
12.28
11.05
11.14
11.08
11.17
11.26
12.81
14.07
12.98
11.17
11.11
11.77
11.57
11.79
11.88
11.96
14.15
13.82
13.90
12.29
11.96
11.90
11.84
11.93
11.87
11.95
15.24
15.46
14.42
13.38
11.78
11.86
14.15
15.07
12.76
Cl
BgCl/1
6.10
6.44
5.13
3.6.2
4.91
4.95
5.17
4.91
6,.4tt
6.44
5*47
5.03
5.03
4.99
5.14
5.18
6.22
6.75
6.19
5.11
5.18
5*1.1
4 .92
5- 07
5.15
5.22
fi.53
e'^42
6.23
5.12
5.12
5.04
5.08
5.16
5.19
5.23
6.95
7.14
6.77
5.95
5.09
4.94
6.80
7.10
5.79
-------
Appendix A. 2 Cruise 2, September 1973
STR t>EP SAMP
1
1 0 C47
1 5 448
1 10 1*49
2 0 442
2 5 443
2 10 444
2 15 445
2 20 41*6
3 0 435
3 5 436
3 10 437
3 15 l»38
3 20 i»39
3 25 440
3 30 1*41
4 0 430
4 5 431
4 10 432
4 1E 433
4 20 434
5 0 427
5 5 428
5 10 429
6 0 424
(• 5 425
6 10 426
7 0 328
7 5 330
7 10 329
8 0 331
8 5 332
8 10 333
6 15 334
8 20 315
8 25 336
o 0 3 40
9 5 ^41
9 10 342
9 15 343
9 20 34U
9 25 345
9 30 '46
9 35 347
9 40 348
ST.C
a
4.0
4.0
4.0
4.3
4.3
4.3
4.3
4.3
4.5
4.5
4.5
4.5
4.5
4.0
4.0
4.0
2.5
2.5
2.5
5.5
5.5
5.5
5.0
5.0
5.C
5.0
5.0
5.0
4.5
4. 5
4.5
4. 5
4.5
4. r;
4.5
4.5
4.5
TSWP
•C
16.8
16.8
16.8
15.9
15.9
15.9
15.9
15.9
15.8
15.8
15.8
15.8
15.6
14.0
11.5
14.8
14.8
14.5
13.0
11.5
14.4
14.4
14.2
14.4
14. 4
14."
11.2
11.4
7.2
1 3.2
12.5
10.4
7.0
6,5
6.4
1 1.0
1 1 . •'•:
•J.6
e.r
7.h
f>.<3
6.-6
6:6
<>.*
PH
8.65
8.63
8.57
8.58
8.53
8.55
S..54
8.55
8.49
8.52
8.54
8.53
8.55
8.49
8.29
8.46
8.49
8.48
8.47
8.28
8.43
8.44
8.45
8.42
8.45
8.U6
3.34
8. 19
8.18
8.48
8.48
8.39
8.27
8. 13
8.04
8.39
fi. U2
B.^6
8.18
8. 16
8. 13
8. 11
8.1*
3.06
CC1SD
-*Bho/CBi
2.46
2.47
2.48
2.18
2.45
2.19
2.45
2.46
2.46
2.23
2.46
2.46
2.39
2.36
2.22
2.40
2.15
2.15
2.31
2.17
2.40
2.14
2.37
2.21
2.42
2.41
2.23
2.20
2.06
2.35
2.33
2.32
2.19
2.15
2.1=)
2.27
2.30
2.19
2.17
2.21
2.22
2.21
2.23
2.21
CHL
mg/m3
1.57
1.69
1.60
1.58
1.54
1.57
1.53
1.46
1.47
1.42
1.49
1.47
1.38
1.19
1.74
1.64
.45
.40
1.74
1.51
4. 16
2.32
2.69
1.07
1.21
.92
1.21
1.67
1.76
'.14
.B6
.72
1.30
1.6i>
1.12
.93
.83
.77
.71
.62
.f 6
PH&B
fraction
.10
.03
.01
.06
.04
.09
.09
.11
.11
.17
.22
.13
.13
.19
.00
.19
.20
.17
.17
.21
.17
.27
.25
. 12
.06
.31
.1U
.06
.34
.15
.23
.34
.11
.04
.23
.26
.32
.34
.37
.42
.44
SIO2
mgSi02/l
.74
.73
.75
.87
.87
.87
.87
.87
.87
.84
.84
.84
.88
.84
1.35
1.09
1.08
1.08
1.15
1.34
1.16
1.17
1.20
1.17
1.13
.26
.24
.53
. 12
.16
.29
1.38
1.58
1.66
1.28
1.20
1.42
1.54
1.58
1.64
1.71
1.73
1.75
N03
«g«/"3
194.5
133.0
133.6
191.9
207.8
243.1
235.8
233.2
267.1
252.6
161.0
148.1
126.9
120.1
199.1
192.7
178.3
162.3
207.7
251.6
206.1
357.1
334.8
203.5
207.9
292.6
299.8
351.4
254.0
255.4
278.0
288.4
348.7
366.8
277.5
260.8
313.6
336. 1
336.0
351.0
360.0
356.9
359.8
TPO4
•gp/m'
4.61
4.27
4.16
4.90
5.09
5.20
3.95
3.92
5.13
5.14
4.60
4.26
5.90
4.54
4.68
4.74
4.07
3.76
3.67
4.04
5.69
3.49
7.58
4.91
4.60
4.49
2.90
3.26
1.78
2.54
3.80
2.94
1.98
1. 16
2.44
.93
1.79
2.13
2.00
1.90
2. 62
1.40
4.95
SP04
»gP/«3
2.95
2.5<»
3.23
2.58
4.01
3.29
3.35
3.27
2.89
U.7H
2.97
4.16
2.89
3.96
3.60
2.70
2.40
3.55
4.18
2.58
2.44
1.60
2.98
2.42
3.21
3.14
1.56
1.45
.79
.60
1.33
.92
1.95
2.16
1.45
.12
504
•gS04/l
15.37
15.16
15.22
15.16
14.71
15.15
15.33
14.17
14,95
15.46
15.39
15.70
15.25
15.94
14.09
14.23
12.32
13.59
13.76
12.83
13.84
14.26
14.0-6
14.00
14.04
13.75
9.36
12.87
13.59
14.96
14.67
9.38
8.97
8.91
8.86
8.92
8.87
8.69
9.23
8.70
8.89
8.71
11.39
Cl
•gci/i
7.02
7.00
6.95
6.72
6.59
6,68
6.78
6.48
6.77
6.84
6,76
6.76
6.69
6*12
6.00
6.50
5.74
6.. 1*6
6.48
5.85
6..4 1
6.33
6-43
6.32
6,39
-------
App. A.2 cont.
N>
!T»
10
10
10
10
If)
11
11
11
11
11
11
12
12
12
14
14
14
14
14
15
15
15
15
15
16
16
16
17
17
17
18
18
18
19
19
19
19
19
OEP
H
0
C
10
15
20
0
5
10
15
20
25
0
C
10
0
c
10
15
20
0
c
10
15
20
0
5
10
0
5
10
0
c;
10
0
5
10
15
20
S&flP
349
350
351
352
353
354
355
356
357
358
359
360
361
362
450
454
455
456
457
458
459
460
461
462
463
464
465
477
478
479
475
474
476
469
470
471
472
473
SEC
D
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.0
4.0
4.0
4.5
4.5
4.. 5
4.5
4.5
5.2
5.2
5.2
5.2
5.2
4.8
4.8
4.8
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
4.5
TERP
«C
11.5
9.0
9.5
8.9
a. 9
14.0
13.9
12.2
1 1.4
1 1.0
9.0
15.1
14.2
12.9
15.0
15.0
15.0
14.0
13.2
14.4
1 4.4
14.4
14.4
14.2
14.5
14.5
14.5
14.5
14.4
14.4
14.4
14.4
14.0
14. fl
14.8
14.6
1 4.5
10.5
PH
8.39
8.2°
8.29
b. 30
8.25
8.46
6.53
8.46
8.40
8.34
8. 18
8.52
8.56
8.48
8.49
8.54
8.54
8.52
8.46
8.46
8.48
8.52
8.53
3.47
8.43
8.48
8.47
8.45
8.48
8.58
8.50
8.50
8.52
8.46
8.56
8.58
8.62
3.27
COND
~* mho/cm
2.29
2.19
2.20
2.2i
2.18
2.32
2.32
2.17
2.14
2.08
2.C5
2.39
2.39
2.29
2.42
2.35
2.35
2.35
2.35
2.35
2.35
2.24
2.40
2.10
2.35
2.27
2.37
2.18
2.3 j
2.50
2.20
2.11
2.35
2.37
2.37
2.17
2.38
2.18
CHL
ng/B3
.54
1.01
1.36
1.36
1.25
1.74
1.76
2.12
1.44
1. 15
.94
1.38
1.49
1.45
1.71
1.72
1.66
1.47
1.U5
1.62
1.60
1.66
1.69
1.60
1.78
1 .74
1.78
1.66
1.74
1.64
1.73
1.71
1.73
1.78
1.67
1.66
1.81
1.78
PHAE
fraction
.31
.18
.18
.13
.17
. 15
.07
.05
.04
.14
.27
.14
. 16
.15
.06
.10
.08
. 15
.10
.09
.07
.12
.09
. 13
.12
.06
.10
.17
. 17
.13
.11
.06
.17
.10
.15
.05
.07
-.01
3102
mgSi02/l
1.23
1.39
1.35
1.34
1.42
1.14
1.02
1.12
1.19
1.27
.98
.98
1. 12
.95
.96
1.05
1.04
1.03
1.02
1.03
1.02
1.04
1.01
1.02
1.03
1.02
1.02
1.02
1.02
1.04
1.07
.95
.97
.97
.98
.97
N03
268. 9
299.0
291.4
324.5
307.8
241.1
233.4
283.2
305.7
316.2
356.9
222.4
210.2
250.9
212.8
233.6
228.4
348.2
339.7
431.9
306.7
218.8
200.7
315.5
277.9
219.2
201.1
210.4
249.6
307.4
211.5
229,8
213.5
211.3
284.3
267.7
251.1
237.9
TP04
•gP/«3
7.84
3. 15
2.23
2.62
2.82
5.78
3.52
3.27
3.05
2.01
5.77
3.19
4.. 71
3.34
4.78
4.31
3.75
3.89
3.20
3.56
3.02
3.67
4.39
3.44
4.84
3.35
2.68
4.26
3.73
3. 19
3.94
2.94
3.52
3.78
2.74
9.88
3.52
2.63
SPO4
«gP/«*
6.06
.82
.66
.35
.40
.56
1.48
1.90
.95
1.26
3.01
1.82
.84
1.24
3.80
2.46
2.20
1.81
1.80
1.99
2.33
1.32
1.98
2.25
2.16
2.00
1.47
2.27
1.93
1.80
1.52
1.68
1.75
2.03
2.67
2.18
2.65
2.78
S04
•gS04/l
9.43
8.78
8.85
13.43
9.10
8.80
9.10
13.69
8.76
8.58
8.88
15.25
8.89
12.29
14.51
14.31
14.23
14.03
13.83
14.01
13.81
10.43
13.53
13.21
12.50
13.69
13.87
14.10
14.41
14.71
14.37
11.02
12.90
13.42
111. 11
14.03
13.96
14.27
Cl
•gcl/1
6.58
6.56
6.«9
6.41
6.31
6.43
6.39
3.55
6.37
6.14.
5.93
6.4.0
6.50
6.43
6.39
6.39
6.42
4.68
5,94
6.44
6.50
6.57
6.51
6.45
-------
App. A.2 cont.
TJ DEP S4HP
22
22
22
22
23
23
23
24
24
24
24
25
25
25
25
25
25
26
26
26
26
26
26
26
27
27
27
27
27
27
27
27
27
27
28
28
28
28
28
28
26
28
28
28
0 483
5 484
10 485
15 486
0 487
5 488
10 489
0 363
5 364
10 365
15 366
0 367
5 368
1C 369
15 370
20 371
25 372
0 373
5 374
*IO 375
15 376
20 377
25 378
30 379
0 380
5 381
10 382
15 383
20 384
25 385
30 386
35 387
40 388
50 389
C 3-90
5 391
10 392
15 393
20 394
25 395
30 396
40 397
50 398
60 399
SEC
n
4,5
4.5
4.5
4.5
4.5
4.5
4.5
5.0
5.0
5.0
5.0
5.5
5.5
5.5
5.5
5.5
5.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
TEHP
•C
14.2
14. -2
14.0
13.2
15.1
15.0
14.9
14.5
14.5
13.2
12.5
14.0
14.0
13.1
11.9
10.0
8.0
12.9
12.8
12.4
10.0
7.0
6.5
6.0
12.1
12.1
11.0
10.4
9.9
7.4
6.8
5.5
5.3
5.2
12.9
12.9
10.8
10.0
8.0
6.8
6.4
5.8
5.5
5.2
PH
8.45
8.46
8.46
8.41
8.47
8.53
8.51
8.56
8.61
8.51
3.43
8.55
8.54
8.50
8.38
8.33
8.25
8.48
3.48
8.52
8.40
8.18
8.09
8.05
8.48
8.48
8.43
8.35
8.32
8.21
8. 11
8.05
8.07
8.06
8.49
8.49
8.40
8.30
8.37
8. 11
8.11
8.16
8.15
3.14
COND
-*Bho/cm
2.55
2.40
2.35
2.32
2.52
2.53
2.51
2.42
2.43
2.34
2.26
2.38
2.35
2.24
2.10
2.07
2.09
2.20
2.21
2.20
2.09
2.10
2.16
2.18
2.23.
2.24
2.12
2.05
2.04
2.13
2.15
2.20
2.22
2.22
2.26'
2.24
2.09
2.09
2.C6
2.13
2.1b
2.1S
2.19
2'.22
CHL
mg/B3
1.72
1.47
1.75
1.46
1.77
1.58
1.72
1.79
1.88
1.85
1.85
1.56
1.73
1.54
1.47
1.47
1.84
1.89
1.87
1.45
1.39
.91
.71
1.85
1.77
1.51
1.30
1.08
1.15
.56
.52
.58
1.74
1.71
1.80
1.44
1.41
1.22
.95
.89
.70
.51
PHAE
fraction
-.08
.20
.08
.17
.07
.09
.10
.11
.12
.10
.13
.10
.11
.08
.11
.12
-.01
.04
-.08
.08
.14
.30
.39
.08
.01
.02
.07
.18
.20
.44
.50
.46
.06
.02
.03
.04
.08
.20
.23
.22
.41
.50
SI02
•gSi02/l
1.02
1.04
1.06
1.13
.89
.89
.92
1.05
1.05
1.05
1.15
1.00
1.00
1.03
1.10
1.24
1.31
1.05
1.04
1.03
1.13
1.50
1.73
1.96
1.11
1.06
1.09
1.11
1.18
1.61
1.60
1.95
2.01
2.03
1.02
1.05
1.07
1.26
1.06
1.33
1.45
1.32
1.36
1.56
H03
246.9
181.3
230.6
251.2
224.5
191.0
169.3
220.6
207.2
189.0
222.0
195.0
188.0
221.0
266.3
299.3
315.4
266.9
260.0
274.5
299.8
348.2
444.2
388.1
278.1
294.1
294.9
314.0
322.4
357.0
363.8
384.5
389.8
389..0
268.9
336.7
334.9
358.4
348.6
369.0
397.2
369.0
380.9
368.0
TP04
3.28
3.99
3.98
4.15
5.14
3.87
3.94
5.30
3.22
2.95
6.39
1».2«
2.91
2.57
3.20
2.37
2.59
4.02
3.23
2.91
3.54
2.38
2.95
2.88
3.19
2.27
3.08
3.10
2.83
3.15
4.57
1.88
4.07
3.20
3.88
2.94
4. 12
2.76
3.35
3.47
3.09
4.24
6.66
2.75
SPO4
2.11
2.47
2.74
2.30
2.44
2.68
2.44
2.54
1.65
1.63
2-06
2.10
1.51
1.00
2.83
2.23
1.36
1.41
1.38
1.57
.89
1.23
1.06
1.58
1.92
1.33
1.48
1.55
1.02
1.55
.99
1.71
3.66
1.51
1.97
1.56
1.87
2.49
1.89
1.87
1.71
2.69
1.92
2.90
S04
»gSO4/l
15.02
14.44
14.62
14.29
14.60
14.78
14.45
14.85
15.27
14.26
11.35
14.63
14.33
13.21
13.87
12.03
8.15
10.05
9.00
8.94
7.40
6.72
6.16
6.84-
7.63
3.64
5.54
3.02
1.97
10.24
9.56
12.16
9.90
11.04
9.50
13.81
9.96
12.32
12.49
9.73
11.85
11.04
12.19
9.31
Cl.
•gci/i
6.53
6.37
6.33
6,. 20
6*64
6,60
6.54
6 .43
6.59
£.33
4.72
6.4.7
6.47
5.94
5.48
5.38
5.15
6.Q3
5.96
5.88
5.40
5.20
5.D1
5.29
5.91
3.85
5.0.0
3.73
.69
4,09
3,28
5,26
3.28
4.63
2.63
6.05
3.. 70
5.39
5.27
3.37
5.23
4.69
5.37
2.26
-------
App. A.2 cont.
ITA
29
29
29
29
29
29
29
29
29
29
30
30
30
30
30
30
30
30
30
31
31
31
31
31
38
38
38
38
39
39
39
39
39
39
39
39
40
40
DEP
«
0
5
10
15
20
2E
30
40
50
6G
0
c
10
15
20
25
30
35
40
0
5
10
15
20
0
5
10
15
0
C
10
15
20
25
30
35
0
5
SAMP
400
401
402
403
404
405
406
407
408
409
410
411
U12
413
414
415
416
4 17
418
419
420
421
422
423
320
321
322
323
312
313
314
315
316
317
318
319
310
311
SEC
a
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
6.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
5.0
5.0
5.0
5.0
5.0
4.5
4.5
4.5
4.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
4.5
4.5
TE«P
°C
10.6
10.6
10.5
8.0
6.9
6.0
5.8
5.0
«.S
4.5
8.8
8.9
8.5
8.2
7.2
6.8
6.5
6. '5
6.4
10.0
9.9
9.8
9.5
8.0
14.9
14.9
14.9
14.0
15.7
15.5
14. 1
13.5
12.2
8.0
8.0
6.2
16.5
16.5
PH
8.35
8.41
8.37
8.34
8.26
3.2*
8.20
8.09
8.05
8.05
8.22
S.29
8.22
8.21
8.13
8.10
8.11
8.10
8.12
8.26
8.26
8.24
8.28
8.18
8.52
8.53
8.50
8.48
8.54
8.53
8.53
8.46
8.47
8.17
8.04
8.02
8.58
8.56
COHD
-*mho/cm
2.16
2.16
2.13
2.C7
2.12
2.12
2.14
2. IP
2.19
2.20
2.05
2.05
2.04
2.04
2.10
2.15
2.14
2.24
2.01
1.83
1.63
1.87
1.86
2.03
2.35
2.35
2.37
2.28
2.06
2.27
2.20
2.10
2.03
2.05
2. 00
2.15
2.17
2.19
CHL
«g/B3
1.32
1.61
2.75
1.37
1.46
1.26
.67
.59
.57
.96
.97
1.09
1.05
.92
.99
.87
.87
.88
1.15
1.37
1.33
1.27
1.07
2.02
1.76
1.80
1.68
1.60
1.63
1.94
1.47
1.37
1.08
.85
.97
1.60
1.53
PHAE
fraction
. 13
-.01
-.02
.06
.26
.22
.36
.34
.44
.07
.08
.17
.18
.24
.21
.28
.31
.30
.12
.10
.05
.10
.18
.06
.07
.03
.09
.08
.08
.03
.03
.07
.28
.31
.25
.03
.05
SI02
jngSi.02/1
1.16
1.18
1.18
1. 12
1.27
1.15
1.31
1.54
1.61
1.65
1.28
1.26
1.40
1.40
1.52
1.51
1.51
1.53
1.51
1.49
1.50
1.49
1.48
1.53
.94
.93
.93
.98
,76
.84
.86
.89
-.97
1.40
1.78
1.81
.72
.75
S03
304.5
313.8
311.9
327.5
343.1
350.8
358.5
415.2
386.5
392.6
352.8
363.6
357.1
386.9
396.2
367.4
383.0
379.6
376.2
353.8
345.7
370.8
362.6
375.1
226.6
211.3
214.0
236.2
193.6
221.3
247.7
261.5
287.9
350.4
386.4
390.6
158.4
187.3
TP04
•gP/«*
3.59
3. 13
7.59
4.54
3.82
3.35
3.47
3.56
3.79
5.03
3.53
4.18
4.22
5. 12
5.18
4.52
3.83
4.59
5.44
3.83
4.08
3. 18
3.82
3.46
3.37
7.04
4.07
3.58
3.17
3.47
3.98
5.19
2.83
2.88
4.49
3.29
2.39
2.41
SP04
BgP/«»
2.27
1.53
2.62
3.21
3. 13
2.06
2.12
2.30
4.00
3.06
3.32
2.30
2.97
2.65
2.82
2.42
2.12
2.65
4.75
2.67
2.04
1.80
2.03
2.78
2.62
1.45
2.31
2.83
.90
1.23
1.11
2.03
3.39
1.38
3.85
1.48
1.15
1.18
SOU
•gS04/l
12.64
12.69
12.98
12.78
5,29
12...Q2
9.14
11.75
9.24
11.96
11.28
9.13
9.18
11.17
11.58
9.07
9.00
11.48
8.97
9.50
9.18
9.71
10.13
9.08
16.45
16.52
15.63
14.39
14.75
14.70
14.64
14.23
15.25
12.22
13.11
12.23
14.39
13.26
CL
•gci/i
*»Si
6.49
6.56
&«.17
6.30
6.28
5,93
S..67
6.29
5 14
i.47
5 .,1ft
6-»17
5/70
-------
App. A.2 cont.
bo
(—>
00
:T» DEP SAHP
K
41 0 300
41 5 309
41 10 308
41 15 307
i»1 20 306
41 25 305
41 30 304
U1 35 303
41 4C 302
41 45 301
1*2 C 290
42 5 291
42 10 292
42 15 293
42 20 294
42 3C 295
42 40 296
42 50 297
42 60 298
42 70 299
43 0 280
43 5 281
43 10 282
43 15 283
43 20 284
43 30 285
43 40 286
43 50 287
43 60 288
43 70 289
44 C 270
44 5 271
44 10 272
44 20 273
44 30 27U
44 50 275
44 70 276
44 90 277
44 100 278
44 110 279
SEC
*
5.5
S.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
6.9
6.9
6.9
6.9
6.9
6.9
6.9
6. 9
6.9
6.9
3.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
TEMP
«C
16.1
16.1
15.5
11.0
8.5
7.6
7.0
S.«
6.1
6.0
15.0
14.5
14.0
12.0
11.0
5.5
4.9
a. 5
4.5
4.4
12.5
12.5
12.5
12.4
6.0
4.6
4.4
4.4
4.4
4.4
12.0
12.0
11.5
5.9
4.5
4.4
4.4
4.2
4.2
4.2
PH
8.51
8.58
8.53
8. 39
8.20
8. 10
3.04
8.00
3.00
8.02
8.48
8.U9
8.48
8.40
8.34
8.06
8.04
8.00
7.96
7.96
8.37
8.43
8.46
8.42
8.32
8. 18
8.12
8.11
8.12
8.11
8.46
8.42
8.41
8.65
8.40
8.12
8. 17
8.08
8.07
8.03
CCND
-*a'ao/cm
2.27
2.23
2.24
2.05
2.00
2.11
2.03
1.89
2.15
2.17
2.20
2.1H
2.21
2.04
1.99
2.11
2.15
2.17
2.11
2.16
2.03
2.00
2.00
2.00
2.20
2.16
2.17
2.19
2.21
2.22
1.96
1.95
1.95
1 .74
2.10
2.12
2.1.2
2.11
2,07
2.16
CHL
mg/B*
1.81
1.85
1.60
1.34
1. 12
.87
.67
.45
.31
.36
1.47
1.54
1.25
1.41
.83
.54
.46
.39
.37
1.92
1.81
1.78
1.73
2.19
1.23
.73
.55
.33
.22
1.94
1.87
1.94
1.98
2.83
.83
.59
.23
.24
.20
PHAt!
fraction
.05
.03
.07
.17
.25
.23
.31
.44
.60
.52
. 15
.11
.21
.12
.20
.38
.47
.50
.53
.01
.05
.04
.09
.09
.23
.27
.30
.47
.67
.03
-.06
-.06
-.03
.08
.20
.22
.57
.63
.70
SI02
ngSi.02/1
.78
.75
.83
.96
1.13
1.29
1.43
1.79
2.00
1.97
.79
.80
.92
.96
1.04
1.40
1.71
1.84
1.90
1.97
1.02
.99
1.00
.99
1. 20
1.38
1.44
1.46
1.55
2.05
.98
.95
.98
1.01
1.23
1.43
1.50
1.61
2.09
2.23
N03
agH/»3
211. 1
179.4
201.7
267.5
306.4
319.7
329.2
348.9
368.7
347.4
222.8
244.0
272.9
292.8
315.3
353.2
314.3
379.0
387.4
381.8
261.7
259.0
252.6
254.7
293.0
326.4
335.7
323.4
325.4
345.6
274.7
264.7
266.8
306.3
325.2
330.9
329.4
335. 1
354.1
361.0
IPO 4
agp/m»
8.72
3.29
3.32
2.80
3.65
2.18
3. 11
1.59
2. 14
3.20
4.04
5.36
4.48
3.57
2.91
3.37
2.76
3.27
2.12
2.88
2.41
2.45
3.08
4.45
3.32
3. 18
3.45
2.41
3.55
2.69
2.33
2.53
2.03
1.94
1.78
1.59
2.46
3.70
SP04
•gP/«*
1.37
1.29
1.40
1.11
.84
.76
.46
.95
1.01
2.34
2.77
2.99
1.92
2.63
1.70
1.45
2.15
1.01
1.08
1.29
.88
.87
2.06
1.24
1.48
1.53
3.00
1.66
2.10
1.39
1.70
1.14
.95
1.24
1.05
.32
.39
1.35
1.70
S04
•gS04/l
13.04
12.64
14.30
11.65
11.27
10.43
10.95
10.91
11.77
11.38
12.60
13.55
12.69
10.69
10.39
11.01
1d.82
10.53
11.25
10.62
11.25
10.95
11.00
10.59-
11.65
10.79
11.29
11.56
12.96
11.31
10.92
10.85
11.92
11.05
11.55
12.05
11.19
12.14
11.27
11.89
CI
•gCl/1
6.15
6.15
6. .13
5.40
4.91
.4.41
5.11
5.17
5,40
5.23
5.89
6.03
5.52
4.84
5. .01
5.14
5,., 28
5.20
5.24
tt..88
-5..09
5.13
5,13
S..93
5.36
J5ufle
5.35
5.16
5.72
5- 19
5 .01
4.88
5. A3
5 ^18
5.30
5*37
4.92
5*39
5.21
5. ,43
-------
App. A.2 cont.
;TA
45
45
45
45
45
45
45
45
45
45
46
46
46
46
46
46
46
47
47
47
47
47
48
48
48
48
49
49
49
49
49
49
49
49
49
50
50
50
50
50
50
50
50
DEP
.1
0
C
10
15
20
30
40
50
60
70
0
c
10
15
20
25
30
0
5
10
15
20
0
c
10
15
0
5
10
15
20
23
30
40
50
0
5
10
15
20
25
10
35
SAHP
260
261
262
263
264
265
266
267
268
269
253
254
255
256
257
258
259
248
249
250
251
252
244
245
246
247
235
236
237
238
239
240
241
242
243
227
228
229
230
231
232
233
234
SEC
m
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
5.5
5.5
5.5
5.5
5.5
5.5
5.5
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
9.0
9.0
9.0
S.O
9.0
9.0
9.0
9.0
9.0
6.0
6.0
6.0
fi.O
6.0
6.C
6.C
6.0
TEHP
°C
11.0
11.0
10.5
10.5
8.2
4.5
4.5
'4 ,U
4.4
4.4
11.8
11.1
10.5
3.5
7.2
6.8
6.5
14.0
13.2
12.6
8.5
8.0
14.5
13.8
12.8
9.0
9.8
9.8
9.8
9.0
8.5
7.4
6.5
5.8
5.8
10.2
10.0
9.2
8.0
7.5
7.0
6.3
6.b
PH
8.28
8.33
8.32
8.28
8.26
8.14
8.13
8.13
8.13
8.07
8.18
8.18
8.11
8.14
8.12
8. 10
8.10
8.12
8.08
8.07
8.03
8.05
8.13
8.12
8.12
3.06
8.24
8.24
8.26
8.30
a. 21
8.19
8.19
8.02
7. 98
8.19
8. 16
8.15
8.12
8.11
8. 10
8.05
8.06
COHD
~* mho/en
1.88
1.93
1.92
1.90
1 .82
1.76
2.00
2.14
2.15
2.15
1.68
1.72
1.80
1 .84
2. 04
2.12
2.17
1.30
1.42
1.42
1.96
1.95
1.36
1.26
1.54
1.94
1 .94
1 .96
1.95
1.96
2.03
2.14
2.16
2.00
1.99
1.83
1.82
1.84
1.94
2.02
2.12
2.15
2.12
CHL
•g/»3
1.69
1.56
1.69
1.43
1.58
1.67
.78
.54
.39
.36
1.80
1.66
1.34
1.19
1.21
1.12
.95
1.34
1.43
1.35
1.12
1.11
1.24
1.28
.98
.53
1.20
1.60
1.62
1.39
1.33
1.32
1.09
.77
.69
1.21
1.41
1.26
1.22
1.04
1.02
1.17
1.00
PHAE
fraction
.06
.07
.00
.08
.09
.23
.24
.33
.39
.50
.04
.08
.11
.22
.18
.21
.26
.17
-.01
.08
.17
.11
.17
.19
.10
.61
.10
-.01
.05
.01
.12
.24
.28
.32
.33
.25
.06
.13
.17
.27
.27
.27
.32
SI02
•gSi02/l
1. 14
1.14
1.27
1.17
1.23
1.37
1.45
1.49
1.60
1.77
1.61
1.58
1.54
1.56
1.51
1.51
1.60
1.88
1.85
1.83
1.66
1.61
1.84
1.90
1.76
1.61
1.36
1.25
1.24
1.27
1.24
1.27
1.38
1.69
1.80
1.45
1.45
1.46
1.46
1.48
1.49
1.56
1.63
NO 3
290.0
280.0
302.6
291.5
311.6
320.9
327.9
332.3
330.8
337.7
324.9
308.9
306.1
315.5
322.4
329.3
327.7
283.1
294.9
294.5
335.2
334.9
280.8
257.6
286.2
316.0
289.8
273.8
269.9
276.8
284.9
293.0
298.7
322.5
324.6
274.3
274.0
279.7
296.3
295.9
306.5
301.3
307.0
TPO4
•gP/«3
1.62
2.07
2.55
3.97
2.69
2.13
2.08
2.18
1.55
3.65
5.36
4.31
3.74
2.68
1.78
1.64
2.77
3.75
3.86
4.48
4.72
6.32
4.94
4.46
2.94
2.85
5.67
3.78
4.66
4.45
5.90
5.26
2.99
3.82
3.04
5.60
4.36
8.09
4.52
6.22
5.12
7.02
4. 14
SP04
•gP/»»
.89
.78
1.32
1.04
1.44
1.26
1.24
1.24
1.27
2.63
2.00
1.89
.81
3.71
.39
.67
2.1B
2.03
3.38
2.60
2.57
1.51
3.17
2.13
1.91
1.51
3.48
2.82
2.42
4.15
3.89
3.03
3.17
1.94
2.70
3.73
2.80
2.94
3.87
3.56
3.37
4.49
3.68
son
•gS04/l
11.27
11.77
11.25
10.72
11.79
11.04
11.42
11.58
12.76
12.69
9.15
9.19
9.69
9.62
12.16
11.52
13.15
8.36
8.29
8.22
10.76
10.92
8.64
8.23
8.50
10.58
10.51
11.00
11.73
10.87
11.48
12.09
12.70
12.40
11.31
10.38
10.76
10.81
11.99
10.22
11.73
11.78
12.28
CL
•gci/i
4.91
4.85
4.97
4.91
5.24
4.96
5.33
5.33
5.41
5.42
3.52
3.97
4.18
4.08
4.98
5.23
5.. 66
2.QS
2.58
2.11
4.64
4.87
2*33
1.73
3 ^^3
4..7J)
4.57
4.94
4.A2
4.8J6
5.09
5.2JS
5.32
5.39
4.75
1*37
4.4.8
4.64
5.01
4.40
5.16
S.2J
5.35
-------
App. A.2 cont.
STA
124
124
120
124
130
130
130
130
130
130
130
130
130
DEP
H
0
c
10
15
0
5
10
15
20
25
30
35
40
SiP!P
324
325
326
327
218
219
220
221
222
223
224
225
226
SEC
m
5.0
5.0
5.0
5.0
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
TEH?
°C
1 4.4
14.4
12.0
10.3
8.5
8.5
7.5
6.9
6.5
6.5
6.4
6.0
6.0
PH
8.47
8. 46
8.45
8.28
8. 11
6.18
8. 15
8. 15
8.09
8.06
8.03
8.04
8.05
CCHD
— * mho/cm
2.33
2.34
2.30
1.87
1.99
2.04
2.05
2.13
2.08
2.19
2.08
2.19
2.13
CHL
•g/n*
1.72
1.66
1.68
1.59
.90
.94
1.12
1.32
1.29
.88
1.09
.81
1.12
PHAE SI02
fraction ngSio2/l
.06 .98
.07 .96
.08 1.07
.14 1.20
.14 1.30
.14 1.34
.14
.06
.11
.33
.24
.41
.14
.41
.42
.47
.48
.52
.55
.55
NO 3
mgN/B*
211. 1
219.4
260.9
277.6
332.8
327.6
324.9
316.1
321.8
307.0
306.7
301.5
296.4
TPOtt
»gP/»a
4.01
4.69
3.08
7.94
4.08
3.94
5.95
4.37
6.67
4.39
4.43
5.08
5.75
SPO4
»gP/»3
1.60
4.46
1.19
1.22
3.66
2.62
5.07
3.71
3.14
3.68
4.11
3.56
S04
•gS04/l
16.23
16.18
14.10
13.10
12.25
12.18
12.11
13.63
12.43
12.24
9.57
13.13
12.49
Cl
•gCl/1
6.J60
6.63
6.17
5.44
5.30
5.28
5.24
6.19
5.54
5.3.7
3.79
5 ..46
5^62
-------
Appendix A,3 Cruise 3, October 1973
STA
1
1
1
2
2
2
2
2
3
3
3
3
3
3
3
4
4
4
4
4
5
5
5
6
6
6
7
7
7
8
8
8
8
8
9
9
9
9
9
9
9
9
9
DSP
H
0
5
10
0
5
10
15
20
0
5
10
15
20
25
30
0
5
10
15
20
0
5
10
0
5
10
0
5
10
0
5
10
15
20
0
5
10
15
20
25
30
35
40
SAMP
513
514
515
508
509
510
511
512
501
502
503
504
505
506
507
496
497
498
499
500
493
494
495
490
491
492
571
572
573
574
575
576
577
578
583
584
585
586
587
588
589
590
591
SEC
a
6.5
6.5
6.5
6.0
6.0
6.0
6.0
6.0
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.3
7.8
7.8
7.3
6.0
•5.0
6.0
6.0
6.0
6.0
7.3
7.3
7.3
7.3
7.3
•7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
TEMP
°C
15.1
15.1
15. 1
15.0
14.9
14.6
14.6
14.5
14.9
14.9
14.9
14.8
14.0
13.5
13.5
14.2
14.2
14.2
14.0
14.0
14.0
14.0
13.8
14.5
14.5
14.4
12.5
12.5
12.2
12.4
12.2
12.1
12.1
12. 1
12.4
12. 3
12.2
12.2
12.2
12.2
12.2
12.0
12.0
PH
8.51
8.51
8.49
8.45
8.46
8.46
8.46
8.44
8.U3
8.46
8.43
8.41
8.37
8.33
8. 31
8.42
8.44
8.44
8.41
8.41
8.35
8.37
8.43
8.44
8.21
8.UO
8.11
8.24
8.28
8.23
8.24
8.29
8.25
S.20
8. 11
8.11
8.22
8.25
8.29
8.34
8.24
8.17
8. 13
COND
-*«ho/cm
2.59
2.54
2.51
2.51
2.H9
2.46
2.48
2.42
2.48
2.52
2.52
2.47
2.44
2.38
2.33
2.45
2.44
2.47
2.46
2.45
2.29
2.44
2.49
2.47
2.45
2.94
2.00
2.00
2.01
2.10
1 .96
1.96
1 .89
1.92
2.13
2.13
2.09
2.02
2.02
2.00
2.04
2.05
2.07
CHi
mg/«3
1.51
1.67
1.65
1.81
1.63
1.65
1.65
1.55
1.67
1.73
1.74
1.61
1.59
1.27
1.28
1.41
1.35
1.47
1.39
1.27
1.59
1.49
1.40
1.84
2.24
2. 14
1.58
1.49
1.56
1.32
1.56
1.62
1.65
1.60
1.44
1. 51
1.56
1.57
1.51
1.58
1.43
1.13
1.22
PHAE
fraction
. 13
.19
.21
-.07
. 15
.13
.13
. 11
.17
.14
.13
.14
.15
.24
.26
.19
.23
.19
.23
.27
.14
.16
.17
.16
.12
.14
.05
.06
.07
.10
.12
.16
. 17
.19
.16
.15
.15
.08
.12
. 11
.11
.23
.19
SI02
mgSi02/l
1.03
1.33
1.03
1.13
1. 15
1.19
1.27
1. 17
1.20
1. 14
1.25
1.36
1.41
1.47
1.35
1. 32
1.32
1.32
1.39
1.43
1.38
1.40
1.43
1.40
1.44
1.55
1.51
1.49
1.46
1.45
1.53
1.50
1.52
1.34
1.44
1.44
1.43
1.37
1.34
1.31
1.39
1.30
N03
158.6
158.4
162.6
182.4
175.0
176.3
180.5
193.2
170.6
167.5
163.1
175.8
194.3
215.7
221.3
171.4
176.9
215.6
185.2
190.8
171.8
177.4
178.7
140.7
153.5
154.8
324.9
311.0
303.2
302.8
307.0
314.2
315.4
325.6
305.7
297.8
286.9
307.7
304.4
302.5
303.7
301.9
301.6
TPO4
•gP/n*
4.64
5.46
4.50
4.47
5.43
4.56
5.12
5.51
4.66
4.44
5.09
4.92
4.91
4.39
4.43
5.41
5.93
5.10
5.36
4.58
5.33
5.85
4.89
5.47
6.07
6.03
4.69
4. 69
5.15
4.27
3.70
4.16
3.36
4.53
3.51
3.50
7.84
10.40
4.19
4.64
4.06
4.06
5.40
SP04
•gP/«»
3.66
3.87
3.79
3.28
4.49
4.58
3.53
4.23
3.99
4.46
3.55
4.20
3.29
3.41
3.33
4.39
4.78
4.30
4.56
3.86
4.70
5.22
4.87
5.84
5.27
4.88
3.75
3.06
3.06
3.37
2.53
2.03
2.34
1.56
1.76
2.08
2.16
2.65
2.81
2.08
2.52
2.03
3.00
S04
•gS04/l
13.99
14.04
14.30
14,09
13.93
14.09
13.50
13.30
14.34
14.40
14.24
13.71
13.55
12.97
12.92
14.39
14.45
14.08
14.56
13.81
14.55
15.1*
14.34
15.29
15.66
15.03
10.83
11.12
11.22
11.72
11.42
10.80
10.77
10.73
11.76
11.66
10.84
11.33
10.90
11.27
11.50
11.53
11.50
CJ.
•9C1/1
6.67
6.50
6.63
6.52
6.55
6.28
6^25
6.21
6*64
6.81
6^54
6.34
6.14
6. .00
5.83
6,^73
6.49
4.A9
£i*32
fc*35
6.»«
6.34
6,40
6 .58
6.58
6.41
4. .89
5.15
5.38
5.32
5.11
4.81
H.7.8
4^36
5*55
5.67
4.97
5.58
5^13
5-29
5.51
5.34
3.53
-------
App. A. 3 cont.
STA DEP 3A«P SFC
H g
PH
CONO
»n ho/cm
CHL
10 0 59?
10 5 593
10 10 594
10 15 595
10 20 596
11 0 519
11 5 520
11 10 521
11 15 522
11 20 523
11 25 524
12 0 516
12 5 517
12 10 518
13 0 707
13 5 7 08
13 10 709
14 0 710
14 5 711
14 10 712
14 15 713
14 20 714
15 0 715
15 5 716
15 10 717
15 15 718
15 20 719
16 0 720
16 5 721
16 11 722
17 0 723
17 5 724
17 10 725
18 0 72f)
1S 5 727
18 1C 728
e.o
8.0
8.0
P.O
8.0
7.5
7.5
7.5
7.5
7.5
7.5
7.0
7.0
7.0
7.0
7.0
7.0
6.5
6.5
6.5
6.5
6.5
6.5
f .5
6.5
6.5
6.5
5.5
5.5
5.5
6.0
6.0
*>•"'
6.E
6.5
6.5
12.5
12.5
12.4
11.8
11.2
12.1
12.1
12. 1
12.1
12.0
12.0
12.0
12.0
12.0
14.0
1 4.0
14.0
13.9
1.3.9
13.8
13.0
13.0
13.5
1-3.5
13.5
13.4
13.0
13.5
13.5
13.5
14.5
14.4
1 3.5
1 3.S
1 1. 8
13.3
8.28
8.26
8.29
8.22
8.17
8.22
8.23
8.29
8.21
8; 20
8.11
8.22
8.21
8.21
8. 42
3.48
8.49
8.41
3.39
8.42
8.40
8.38
8.34
8.37
3.44
8.42
8.36
a. 44
8.42
8.41
8.52
8.50
8.44
«. 37
8.47
8. 37
2.02
2.02
2.04
1.96
1.96
2.00
1.99
2.00
2.00
1.99
1.97
1.96
1 .94
1.94
2.37
2.37
2.37
2.40
2.37
2.35
2.32
2.30
2.43
2.41
2.32
2.32
2.3U
2.37
2.34
2.34
2.5ii
2.4B
2.33
2.3?
2. 3<;
2.34
1.09
1.46
.24
.52
.27
.06
.35
1.35
1.53
1.60
1.24
1.37
1.51
1.38
1.40
1 .44
1.46
1.41
1. 54
1.70
1 .44
1.27
1.03
1.26
1.05
1.48
1.33
1.25
1. 17
1. 16
1.22
1.47
1.51
1.24
1.19
1.20
PHAE
fraction
.13
.10
.25
.13
.22
.17
.10
.08
.09
.09
.15
.10
.07
.17
.12
.16
.17
.15
.13
.15
.21
.31
. 14
.17
.22
.14
.11
.24
.27
.07
. 18
.17
. 13
. 13
.22
.18
SI02
»g Si 02/1
1.33
1.33
1.35
1.32
1.46
1.65
1.58
1.58
1.58
1.59
1.58
1.64
1.64
1.59
1.01
.96
.95
i96
.96
1.03
1.04
1.17
1.08
1.07
1.06
1.09
1. 12
1.08
1.05
1. 11
2.12
1.73
1. 17
1.02
1.13
1.08
HO 3
ngB/a*
308.8
314.5
308.1
310.8
325.5
298.4
295.4
309.6
293.6
299.2
303.4
263.0
288.7
300.0
248.0
234.1
229.2
243.6
254.6
246.7
250.7
259.2
246.8
247.8
245.8
249.8
259.8
247.4
236.5
244.9
193.7
200.7
228.6
235.6
238. 1
236. 1
TP04
•gP/»3
5.77
5.44
8.79
6.25
5.43
5.37
3.32
2.16
2.08
5.28
2.17
3.89
4.24
3.67
2.84
3.23
2.96
2.54
2.69
3.15
2.88
3.58
3.42
3.62
3.04
3.50
3.50
3.31
2.96
3.43
4.10
3.95
3.45
3.65
4.35
3.93
SPO4
3.82
4.38
4.75
5.15
3.81
2.78
3.25
.95
1.43
1.50
1.61
2.87
2,96
2.69
2.33
2.75
2.14
1.91
2.33
2.29
2.14
1.83
2.06
2.37
2.45
2.26
2.26
1.50
1.89
2.60
2.33
2.61
2.22
2.69
2.97
2.47
SO4
mgSOH/1
11.01
10.98
11.08
11.31
11.15
9.75
10.01
9.75
9.80
9.86
9.70
10.22
9.74
9.80
12.66
12.68
12.76
12.62
12.59
12.51
11.48
11.67
12.47
12.27
11.91
12.05
11.52
12.10
11.46
11.76
9.47
10.82
11.51
19.88
20.19
17.21
Cl
•gci/i
5.05
5.20
5.J11
5.15
5..09
5.13
5.36
5.36
5 ..19
5.22
5.08
4.2u
5.11
5.«10
6.60
6.68
6.62
6.63
6.55
5 .55
6.3.0
6.31
6.46
6.117
6.65
6.56
6 .JO
6.44
6.35
6 .70
6.10
6.39
6.50
6 ..88
6.69
6.23
-------
App. A.3 cont.
K>
I—i
oo
ST»
1 9
19
19
19
19
20
20
20
21
21
21
22
22
22
22
23
23
23
24
24
24
24
25
25
25
25
25
26
26
26
26
26
26
26
27
27
27
27
27
27
27
27
27
27
DEP
H
0
5
10
15
20
0
5
10
0
5
10
0
5
10
15
0
5
10
0
5
10
15
C
C
10
15
20
0
5
10
1 5
20
25
30
0
c
10
15
20
25
30
35
40
50
SAUt
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
76?
764
765
766
767
768
769
770
771
772
SEC
m
7.0
7.0
7.0
7.0
7.0
5.5
5.5
5.5
8.0
8.0
e.n
6.5
6.5
6.5
6.5
7.0
7.0
7.0
6. .8
6.8
6.8
6.8
8.0
8.0
9.0
8.0
8.0
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.0
7.0
7.0
7. 1
7.0
7.0
7.0
7.0
7.0
7.0
TSMP
•c
13.5
13.5
13.4
12.9
12-. 8
13.5
13.0
13.0
12.6
12.15
12.5
13.5
13.3
12.8
12.5
13.6
13.5
12.5
12.6
12.5
12.0
11.8
12.5
12.5
12.4
12.4
12.3
12.8
12.6
12.5
12.5
12.4
11.5
11.0
12.8
12.6
12.5
12.14
12.0
1 1.9
1 1.6
10.5
7.5
7.2
PH
8.41
8.45
8.47
8.37
8.24
8.43
8.44
8.41
8.35
8.34
8.29
8.41
8.41
8.28
8.29
8.37
8.40
8.41
8.32
8. 34
3.37
8.27
8.28
8.30
8.34
8.37
8.28
8.25
8. 32
8.25
8.29
8.25
8.12
7.98
8.29
8.32
8.28
8. 2U
8.16
3. 15
8.19
8.21
8.09
7.94
COND
-» mho/cm
2.38
2.41
2.34
2.26
2.25
2.27
2.13
2.07
2.03
1.98
1.93
2.36
2.30
2.09
2.00
2.39
2.34
2.34
2.17
2.15
2.05
1.89
1.94
1 .92
1 .90
1.90
1.93
1 .95
1.93
1 .90
1.91
1.91
1.91
1.92
1.90
1 .87
1.85
1 .90
1 .90
1.92
1.93
1 .95
2.00
2.12
CHL
ng/rn*
1.18
1. 10
.59
1.64
2.03
1.23
1.16
1.79
.54
1.72
1.06
1.59
1.17
1.60
1.43
1.36
1.36
1.45
1.35
.91
1.63
1.40
2.19
1.89
2.08
1.51
1.03
1.83
1.78
1.81
1.77
1.38
.89
.72
1.81
1.81
1.81
1.52
.91
.85
.86
.70
.71
.61
PHAE
fraction
.24
.21
.20
.22
. 19
.14
.25
.08
.24
.03
.20
.09
.15
.05
.16
. 16
.15
. 16
.12
.38
.15
.23
.04
.01
.06
.13
.21
.01
.11
.06
.07
.13
.25
.30
.00
.01
.02
.13
.29
.27
.28
.33
.24
.43
SI02
ngSi02/l
1.02
1.03
1.07
1.28
1.25
1.15
1.31
1.29
1.37
1.32
1.22
1. 11
1. 11
1.05
1.12
1.25
1.27
1.27
1.30
1.21
1.13
1.16
1.11
1.10
1. 10
1.13
1.10
1. 12
1.20
1.00
1.12
1.08
1.18
1.37
1.28
1.08
1. 19
1.11
1.17
1.20
1.16
1.22
1.30
1.65
H03
238.6
245.6
236.2
255.1
242.7
245.2
256.3
253.3
270.7
268.7
298.1
258.8
259.8
256.4
223.1
245.0
240.0
247.0
283.9
284.9
278.5
312.3
310.4
296.4
301.9
319.4
310.0
314.0
323.9
314.5
309.6
307.6
316.1
321.6
321.1
310.2
347.0
321.2
305.8
320.2
316.8
317.8
330.8
360.1
TP04
•gP/»3
3.04
3.43
3.48
4.38
4.42
3.45
6.38
3.73
4.36
3.94
4.49
5.51
3.96
4.55
3.85
3.93
3.98
3.17
3.60
5.39
4.70
4.59
3.85
4.63
3.86
3.13
3.37
3.61
3.88
5.01
3.85
3.09
2.98
4.76
3.76
6.09
7.11
6.84
4.69
4.49
3.61
3.65
3.87
SP04
•gP/.'
2.75
3.14
2.99
3.58
2.34
2.66
2.70
3.05
4.03
2.52
2.80
3.81
2.61
3.01
2.43
2.47
2.29
2.64
2.92
2.26
2.31
2.31
2.47
2.32
2.02
3.03
2.18
2.27
2.62
2.20
2.32
2.60
2.02
1.76
2.23
2.00
2.47
3.02
4.12
2.55
2.93
2.09
2.32
S04
•gS04/l
20.45
20.65
20.72
18.80
14.31
16.02
15.39
9.49
9.22
8.36
10.18
17.63
16.89
9.23
6.26
16.41
17..42
16.68
14.40
14.01
13.03
9.94
9.90
8.10
8.41
10.24
9.84
9.79
9.99
8.54
9.66
10.22
10.29
10.48
8.32
6.53
7.54
8.89
9.56
9.99
12.07
12.15
13.05
14.89
CL
•gcl/l
6.58
6.82
6.60
6.34
5.50
5uJB2
5.66
ft.J»0
4.31
3.99
-------
App. A. 3 cont.
ST» DEP SASP SEC
n
28 0 773
28 5 774
28 10 775
28 15 776
28 20 777
28 25 778
28 30 779
28 40 780
28 50 781
28 60 782
29 0 783
29 5 784
29 10 785
29 15 786
29 20 787
29 25 788
29 30 789
29 40 790
29 50 791
29 60 792
3C 0 793
30 5 794
30 10 795
30 15 796
30 20 797
30 25 798
30 30 799
30 35 800
3C 40 801
3' 0 802
31 5 803
31 10 804
31 15 805
31 20 806
32 0 567
32 5 568
32 10 569
32 15 570
33 0 563
3? £ 564
33 10 565
33 15 566
n
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.4
7.4
7.4
7.4
7.4
7.4
7.4
7.4
7.4
7.4
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
6.0
8.0
8.0
8.0
8.0
8.0
7.5
7.5
7.5
7.5
9.5
9.5
9.5
9.5
TESP
•c
12.2
12.1
12.0
11.6
11.4
11.0
10.5
8.8
6.9
6.9
12.1
12.0
11.9
11.8
11.5
10.8
10.0
5.8
5.0
4.8
13.0
13.0
13.0
1 3.0
12.8
12.0
10.5
10.0
9.9
13.1
13.1
13. 1
13.1
13. 1
12.8
12.8
12.6
12.5
12.5
12.4
12.2
12. 1
PH
8.24
8.24
8.29
8.31
8.29
8.24
8.17
8. 14
7.94
7.96
8.22
8.20
8.21
8.20
8.29
8.24
8.20
8.11
8.08
8.02
8.22
8.25
8.19
8.18
8.14
8. 16
8.05
8.04
7.99
8.24
8.30
8.29
8.24
8.25
8.22
8.21
3.21
8. 17
8.24
8.21
8.27
8.2*
C08D
-» mho/cm
1 .83
1.77
1.79
1.86
1.91
1.92
1.97
2.00
2.11
2.13
1.78
1.81
1.81
1.81
1.83
1.90
1.8f
2.00
1.98
2.11
1.71
1 .73
1.65
1.67
1.71
1.77
1.87
1.92
1.95
1.72
1.70
1.70
1.70
1 .71
1.80
1.74
1 .77
1.73
1.87
1 .84
1 .87
1.81
CHL
rng/B'
1.92
1.92
1.88
1.54
.95
.81
.76
.74
.71
.49
1.94
2.01
1.77
2.12
1.67
1.21
.83
.57
.63
.45
1.87
1.96
1.81
1.94
1.30
1.08
.76
.65
.96
1.77
1.70
1.89
2.00
1.86
1.79
2.01
1.88
1.33
1.79
1.81
2.01
1.89
PHAE
fraction
.00
.01
-.00
.08
.25
.36
.34
.34
.40
.53
-.02
.05
.05
.03
.13
.25
.24
.40
.44
.47
.08
.02
.06
.04
.31
.16
.30
.40
.34
.07
.02
.04
.04
.00
.05
-.10
-.00
.15
.08
-.01
-.02
-.02
SI02
•gSiO2/l
1.22
1.32
1.16
1.30
1.18
1.20
1.12
1.32
1.61
1.53
1.19
1.19
1.15
1.16
1.13
1.18
1.20
1.37
1.42
1.50
1.41
1.48
1.40
1.45
1.31
1.45
1.49
1.49
1.55
1.46
1.53
1.42
1.46
1.43
1.60
1.53
1.57
1.59
1.28
1.36
1.30
1.36
H03
•gH/B3
323.8
333.8
321.4
319.4
310.0
315.5
316.5
331.0
351.4
364.4
317.6
321.6
318.2
311.7
312.7
303.3
313.3
344.2
354.7
397.6
349.3
330.6
341.6
313.7
322.4
312.9
333.0
325.7
350.4
318.0
310.7
312.6
341.8
330.0
330.8
322.9
348.2
329.8
332. 1
328.7
319.4
328.1
TPO4
•gP/m*
3.60
3.60
2.87
3.17
3.02
2.98
4.72
3.50
3.00
3.23
5.70
3.71
3.37
3.74
3.70
3.17
3.01
2.66
2.81
3.04
6.05
3.94
3.48
2.95
3.66
2.90
3.16
3.31
3.31
3.34
4.14
5.82
5.01
5.62
5.52
5.22
5.49
4.65
5.71
5.63
5.21
4.91
SP04
•gP/»*
2.54
2.31
2.49
1.77
1.96
2.10
2.37
2.86
2.02
2.28
2.20
2.80
2.42
2.19
2.26
2.45
2.02
1.94
1.90
2.20
1.93
3.75
1.77
1.73
1.58
2.18
2.33
1.98
2.40
2.09
2.35
2.84
2.61
2.76
4.24
4.09
3.97
3.44
5.00
4.62
4.58
4.32
SOU
•gS04/l
10.20
9.83
10.14
11.28
11.95
12.28
12.13
13.61
14.75
15.43
10.03
10.35
10.32
10.53
11.20
11.53
11.96
13.68
15.4'6
15.02
8.93
8.56
8.17
8.50
9.17
9.60
11.68
12.35
13.37
9.37
8.89
8.97
8.94
8.92
10.42
10.06
10.03
10.00
10.55
10.52
10.49
10.86
Cl
•gCl/1
4.17
4.08
4.25
S .53
4*77
4.92
4.^76
5*0.7
5.32
5.33
lull
4.29
4.43
4^27
4.45
4.53
4.67
5.22
5.23
5.3.1.
r
3.58-
3.66
3.90
3^65
.3.86
4..20
4.58
4.73
4MT
3.85
3.79
3.84
3.82
3.96
«.C4
4.01
4.03
4.J07
4. J7
4.50
4.4.7
4.45
-------
App. A.3 cont.
STA
34
34
34
34
34
34
34
34
35
35
35
35
35
35
35
35
35
35
. , 36
to ,,
ho 36
0 36
36
36
36
36
36
36
36
37
37
37
37
37
37
37
37
37
37
38
38
38
38
DEP
H
0
5
10
15
20
25
30
35
C
5
10
15
20
25
30
35
40
45
0
5
10
15
20
25
30
35
40
4E
0
5
10
15
20
25
30
35
40
45
0
5
10
15
SAHP
555
556
557
558
559
560
561
562
545
546
547
548
549
550
551
552
553
554
535
536
537
538
539
540
541
542
543
544
525
526
527
528
529
530
531
532
533
534
699
700
701
702
SEC
n
9.5
9.5
9.5
9.5
9.5
9.5
9.5
9.5
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
7.5
6.5
6.5
6.5
6.5
TEKP
oc
12.4
12.4
12.2
12.0
11.9
11.3
10.7
9.0
12.2
12.1
12.0
12.0
11.8
11.3
10.8
10.0
8.C
7.2
12.2
12.2
12.2
12.. 0
11.9
11.5
11.0
10.5
9.8
7.0
12.8
12. 2
12.2
12.0
12.0
12.0
12.0
1 1. 5
tt.O
7.5
13.9
13.8
12.2
12.1
pa
8.10
3.29
8.25
8.22
8.14
8. 10
8. 15
7.98
8.24
8.27
8.28
8.45
8.28
8.25
8.17
8.21
7.9'4
7.98
8. 15
8.18
8.24
8. 17
8.22
8. 15
8.09
8.10
8. 11
7.92
8.28
8. 30
8.29
8.27
8.29
8.29
8. 19
8. 18
8.00
7.77
8.38
8.44
8.47
8.37
COND
-«nho/cm
1.84
1.84
1 .79
1.87
1.89
1 .87
1.96
2.00
1.95
1.91
1.91
1 .88
1.84
1.92
1.91
2.00
2.01
2.01
2.07
1.96
1.96
2.06
2.04
1.85
1.93
1 .94
2.01
2.08
2.22
2.13
2.09
2.06
2.07
2.07
2.13
2.13
2.09
2.19
2.31
2.32
2.17
1.85
CHL
mg/m3
1.68
1.84
1.87
1.34
1.20
.84
.80
.89
1.80
1.71
1.69
1.42
.93
.79
.63
.52
.57
.54
1.32
1.72
1.82
1.34
1.14
.94
.65
.66
.53
.78
1.31
1.52
1.56
1.54
1.33
1.17
1.17
.84
.83
.68
1.68
1.86
1.88
1.73
PHAE
fraction
.08
.09
-.03
. 12
.15
.31
.31
.22
.00
.05
.03
.14
.29
.35
.39
.57
.41
.47
.11
.04
.06
.'19
.23
.26
.36
.37
.45
.30
.13
.12
.10
.10
.15
. 13
.21
.29
.37
.47
.03
.06
.11
.11
SI02
»gsio2/l
1.51
1.41
1.46
1.59
1.56
1.50
1.67
1.57
1.69
1.40
1.82
1.41
1.42
1.57
.42
.51
.75
.93
.45
.47
1.53
1.85
1.48
1.55
1.52
1.75
1.60
1.90
1.41
1.48
1.52
1.52
1.52
1.52
i. 52
1.58
1.85
1.99
1.17
1.13
1.22
1.16
N03
322.6
311.8
317.5
318.6
J16.8
322.5
328.2
336.9
297.3
294.0
289.1
306.9
305.0
292.6
313.4
322.1
339.9
357.7
294.4
278.5
285.5
254.0
276.3
294.1
302.8
322.1
344.4
242.9
277.2
284.2
285.5
283.9
280.9
285.0
286.3
322.0
334.8
261.8
247.9
266.8
314.1
TPO4
mgf/t*
6.35
6.55
7.23
7.85
5.78
5.44
6.09
5.25
3.88
3.38
5.09
3.69
2.75
2.54
1.96
S. 14
6.16
7.35
2.74
2.12
7.22
3.53
4.05
2.70
2.41
4.03
2.35
3.48
2.08
2.69
2.48
2.80
3.03
2.98
1.92
2.56
2.96
3.73
3.38
4.15
5.03
4.42
SP04
•gP/«'
6.68
5.46
5.69
9.79
5.99
5.46
5.80
5.15
8.89
2.05
9.41
1.87
1.98
3.56
1.32
4.59
4.97
5.88
1.81
1.68
2.12
10.81
2.63
2. 10
2.45
6.44
2.44
1.78
1.75
1.93
1.23
1.75
1.78
1.73
1.76
1.88
1.75
1.86
2.09
2.05
2.67
2.36
S04
•gSO4/l
10.94
10.78
10.74
11.70
11.54
10.78
11.01
11.12
12.78
11.36
12.58
11.03
10.87
11.23
11.20
11.17
11.73
12.49
9.«1
9l23
9.39
11.94
9.71
9.66
9.50
10.51
11.46
11.82
9.65
10.18
10.13
9.96
10.23
9.86
9.12
9.87
10.02
10.02
11.51
11.65
9.96
7.56
ct
•gci/l
«.9Z
4.37
4.84
5-99
5,. 2 5
1»j66
5 .03
4.7,6
6..8A
4.79
7.19
5. .13
4.7,2
5..19
5.3ft
S.17
5.29
5«,9«
4.98
4.51
5.20
8.47
s..te
5.57
5.51
7 ..06
5.53
5.51
9.65
sis*
5»17
5.36
5.33
5.23
5.39
5*25
5.25
.5 .2.8
6.18
6.16
5.63
4.60
-------
App. A.3 cont.
N>
STA DEP SBNP
H
39 0 691
39 5 692
39 10 693
39 15 694
39 20 695
39 25 696
39 30 697
39 35 698
40 0 689
40 5 690
41 0 679
41 5 680
41 10 681
41 15 682
41 20 683
41 25 684
41 30 685
41 35 6 86
41 40 687
41 45 688
42 0 669
42 5 670
42 10 671
42 15 672
42 20 673
42 30 674
42 40 675
42 50 676
42 60 677
42 70 678
43 C 659
43 5 660
43 10 661
43 15 662
43 20 663
43 30 664
43 40 665
43 50 666
l>3 60 667
43 70 669
SEC
7.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
6.5
6.5
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.C
9.5
9.5
9.5
9.5
9.5
9.5
'•*.5
9.5
9.5
9.5
TEHP
•C
12.5
12.4
1 1.8
11:5
11.2
11.2
11.0
10.0
13.0
13.0
12.0
11.0
10.6
10.5
10.4
10.4
8.0
7.6
6.9
6.6
11.0
10.5
10.4
10.0
9.0
6.6
5.0
5.0
a. 9
4.9
1Z.O
1 1.6
1 1.4
1 1.0
10.0
6. 5
4.9
4.5
4.5
4.4
PH
8.30
8.30
8.31
8.28
8.24
8. -18
8.17
8.13
8.34
8;34
8.32
8.31
8.38
8.37
8.32
8.18
8.17
8.06
7.96
7.87
8.28
8.37
8.33
8.30
8.28
8.10
8.01
7.84
7.92
7.83
8.34
3.37
8.43
8.29
rf.28
8. 18
3.22
3.04
8.05
7.<53
COND
2.07
2.06
2.01
1.94
1 .98
2.11
2.05
2.05
2.26
2.20
2.16
2.14
2.09
2.07
2.14
2.07
2.15
2.10
2.17
2.1(1
2.15
2.17
2.08
2.09
2.09
2.16
2.09
2.03
2.09
Z. 13
2.00
2.00
1 .96
2.00
1.03
2.16
2.06
2.22
2.12
2.21
CHL
1.27
1.29
1.41
1.65
1.45
1.06
1.16
1.01
1.02
1.21
.81
.89
1.85
1.72
1.36
1.27
1.04
.91
.71
.49
.95
1.39
1.49
1.31
1.32
.81
.96
.54
.45
.53
1.73
2.21
1.83
1.90
1 . 32.
1 . 33
1. 12
.51
.41
.40
PHAE
fraction
.07
.10
.06
.06
. 11
.27
.21
.28
.24
.14
.29
.31
.01
.07
.20
.16
.17
.34
.41
.47
.05
.19
.17
.13
.13
.33
.23
.42
.55
.46
-.02
-.01
.03
.11
.17
.23
.26
.44
.43
.51
SI02
mgSi.02/1
1.15
1.08
1. 11
1.13
1.17
1.19
1.25
1.34
1.17
1.14
1.05
1.05
1.06
1.00
1.05
1.07
1.13
1.36
1.49
1.63
1.29
1.32
1.34
1.38
1.28
1.28
1.20
1.49
1.45
1.46
1.10
1.09
1.09
1.11
1.23
1'.32
1.36
1.66
1.76
1.74
NO 3
•g N/B3
285.0
295.0
312.4
320.9
317.4
318.4
292.4
319.5
290.4
260.1
290.-3
278.6
281.2
285.3
283.7
289.2
300.4
321.2
338.6
302.6
282.3
286.4
284.7
288.8
321.6
311.3
332.7
336.7
337.9
299.1
287.4
298.7
279.8
295.4
312.4
315.0
336.3
340.4
337.3
IP04
•gP/»'
2.26
2.41
3.22
3.72
2.88
3.72
3.53
2.76
3.10
2. 80
2.94
2.75
3.79
3.56
2.91
2.75
2.87
5. 15
2.79
2.49
3.79
3.15
7.09
4.46
3.55
3.14
3. 17
3.17
3.14
3. 10
3.02
3.19
3.78
5.16
3.50
3.56
3.30
2.55
2.64
3.12
SP04
«gP/»»
1.86
1.59
1.67
1.59
1.78
1.90
2.59
2.13
1.70
2.05
2.27
2.27
2.23
2.16
2.04
2.08
2.85
1.81
2.28
1.62
2.20
2.18
2.58
3.17
2.77
2.23
2.38
3.00
2.46
2.08
2.16
2.02
2.23
2.09
2.38
2.31
3.37
2.27
2.05
2.84
S04
•gS04/l
8.55
8.47
8.16
8.30
8.5«
9.07
9.42
9.39
10.49
10.73
10.57
11.03
10.23
10.20
10.17
10.26
9.34
9,69
9.50
9.31
11.81
12.22
11.75
10.50
11.41
10.56
10.19
10.71
10.52
9.83
11.43
11.72
11.38
11.80
11.65
12.08
11.73
11.46
11.43
11.39
Cl
•gCl/1
5.05
ft. 96
4.97
JUS 5,
5 ..13
5*34
5.62
5.52
5.34
5.92
5.82
5.87
5.85
5.86
5.84
5.32
5.79
5uJ»3
5.38
.5.. 35.
&J.7
5.75
5.76
5*7,41
5-75
5.69
5.71
5..JM
5.63
5.61
5*14
5.05
5.41
5.36
5.47
5.48
5..3A
£..57.
5,. 66
-------
App. A.3 cont.
NJ
M
NJ
TA
00
00
04
00
00
00
00
00
44
00
05
05
45
05
05
45
45
05
05
05
06
06
06
06
06
06
06
07
07
07
07
07
08
08
08
48
49
09
09
49
09
09
09
09
09
DBF
r
0
5
10
20
30
50
70
90
100
1 10
0
5
10
15
20
30
00
50
60
7C
0
5
10
15
20
25
30
0
5
10
15
20
0
5
10
15
0
5
10
1 5
20
25
30
00
50
SAMP
609
650
651
652
653
650
655
656
657
658
639
640
641
642
603
600
605
606
607
608
632
633
630
635
636
637
638
627
628
629
630
631
623
62"
625
626
610
615
616
6.17
618
619
620
621
622
SEC
ID
11.5
11.5
11.5
11.5
11.5
11.5
11.5
11.5
11.5
11.5
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
12.0
7.0
7.0
7.0
7.0
7.0
7.0
7.0
4.0
0.0
U.O
0.0
0.0
3.3
3. 3
3. 3
3.3
6.0
6.0
6.0
6.0
6.0
6.0
6. C
6.0
6.0
TEMP
°C
11.5
11.5
11.5
11.0
9.0
0.5
0.4
4.2
0.2
0. 2
11.5
11.5
11.0
11.0
10.0
6. 0
5.0
0.9
0.6
0.5
13.5
13.0
12.5
12.2
1 1.2
9.8
8.6
10.2
13.9
12.5
12.0
11.1
10.6
1 0.0
13.5
12.5
13.0
13.0
13.0
12.5
1 1.8
10.5
9.5
9.0
6.fi
PH
3.37
8.39
8.02
8.00
8.25
d. 16
8.11
8. 11
8.03
3.03
8.25
8.30
8.33
8.37
8.30
8.16
8.06
8.01
7.99
7.98
8.27
3.17
8.16
8.19
8.10
8.09
8.08
8.09
8.09
8.08
8. 15
8. 11
8.10
8.16
8. 14
8.09
3.21
8.22
3.24
8.22
8. 19
8. 20
8.10
8.04
8.01
COND
-*fflho/Cin
1 .95
1.96
1.92
2.02
2.00
2.17
2.11
2.21
2.10
2.23
1 .91
1.93
1.93
1.93
2.00
2.08
2.15
2.12
2.20
2.11
1.67
1.71
1.71
1 .76
1.87
1.95
2.00
1.32
1.05
1 .70
1.82
1.83
1.21
1.16
1.51
1 .73
1.58
1 .66
1.60
1.66
1.84
1.96
1.96
2.07
2.12
CHL
mg/mJ
1.22
1.93
2.17
.93
1.22
.50
. 32
.23
. 19
. 15
1.03
1.68
1.03
1.01
1. 11
1.14
.69
.56
.53
.00
.82
1.31
1.30
.97
.90
.60
.70
1.05
1.50
1.29
.97
.91
1.38
1.60
1. 12
.97
1.60
1.71
1.76
1.28
1.02
.83
.91
.77
.61
PHAE
fraction
.05
-.01
.01
.35
.26
.08
.53
.65
.70
.71
. 11
.03
.18
.07
.12
.18
.33
. 38
.05
.53
i10
.07
.13
.29
.22
.02
.05
.18
.08
.09
.23
.30
.10
.13
.26
. 15
.00
.01
.02
. 15
.22
.32
.33
.37
.03
SI02
•gSi02/l
1. 30
1. 15
1.12
1.30
1. 13
1.42
1.45
1.82
1.81
1.82
1.25
1.21
1. 10
1.14
1.05
1.31
1.61
1.70
1.73
1.78
1.00
1.05
1.08
1.00
1.35
1.01
1.55
1.76
1.71
1.06
1.06
1.45
2.25
1.89
1.63
1.05
1.53
1.63
1.54
.07
.39
.36
.57
.39
.63
N03
»gH/B»
285.6
278.2
288.0
230.3
296.2
331.9
321.6
337.2
351.3
345.3
257.7
283.3
308.9
295.8
302.7
295.3
339.6
302.3
339.2
359.1
326.8
319.4
314.8
317,5
323.0
328.5
338.0
327.0
322.5
331.2
338.5
256.6
318.2
319.3
325.0
333.7
322.6
300.2
328.0
327.7
336.0
330.5
319.1
336.9
356.2
TPOO
•gP/«3
3.28
0.07
3.28
3.18
3.06
3.01
2.37
2.93
3.22
3.15
6.90
3.37
3.20
2.98
3.27
2.70
2.99
2.69
2.67
3.07
2.33
3.65
2.77
3.25
3.31
2.59
3.65
3.23
7.16
3.10
2.38
2.05
0.05
3.85
2.78
2.81
3.31
3.18
3.17
2.77
3.55
2.76
0.00
3.09
2.61
SPOO
mgp/m*
6.35
3.33
3.07
2.20
3.07
2.12
2.02
1.73
2.07
2.95
2.61
2.82
2.10
1.81
1.71
1.96
2.55
1.72
2.05
3.30
1.22
1.05
1.88
1.39
2.06
1.58
2.29
1.85
2.07
2.06
.93
1.15
3.87
2.57
1.23
2.79
1.92
1.60
1.36
1.19
1.80
6.78
1.09
1.04
S04
•gS04/l
12.50
11.19
11.36
10.16
11.31
11.55
11.27
11.63
11.67
11.90
10.20
11.11
11.54
11.26
11.81
11.14
11.89
11.74
1 1.-84
11.88
10.41
10.38
10.49
10.59
11.21
11.31
11.67
9.89
9.86
10.35
10.90
10.88
10.62
9.82
9.93
10.68
10.32
10.17
10.01
10.25
11.38
11.61
13.44
11.88
11.99
CJ.
•gcl/i
6.<15
5.06
5.45
3.34
5,^07
5.32
0.89
5.41
5^62
5.70
2.94
4.40
0.99
5^20
5.05
•U31
5.34
5.39
5*71
5.^62
3.76
3.78
0-.16
4, ..31
4.69
&~&3.
5.67
2.55
2.70
3.99
4.88
4..50
5.65
2.51
2 .,90
-------
App. A.3 cont.
ST4 DEP SJHP
50
50
50
50
50
50
50
50
124
124
12U
12U
130
130
130
130
130
130
1 30
N3 130
IS 13°
?"
0
5
1 0
15
20
2 c
30
35
0
5
10
15
P
5
10
1 5
20
TC
30
35
no
606
607
608
609
510
611
612
613
703
704
705
706
597
598
599
600
601
602
603
60U
605
SEC
ffl
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
8.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
9.0
•" 2R?
•C
13.0
13.0
13.0
13.0
12.5
10.1
9.0
9.0
13.0
13.0
12.5
12.0
12.9
12.9
12.9
12.6
12.5
1 1.5
10.0
3.9
8.0
PH
3.15
a. 12
8. 16
8.2"8
8.21
8.05
8.07
8.02
8.35
8.34
8. 34
8. 28
8.22
8.22
8.21
8.27
8.21
8.23
8.02
7.96
7.98
COVD
— 'who/cm
1 .73
1 .74
1.67
1.70
1.69
1.95
1.80
1.98
2.25
2.19
2.21
2.11*
1.76
1 .73
1.77
1.72
1.78
1.83
1.95
2.01
2 .no
CHL
mg/m3
1.98
2.04
2.09
1.9U
1.24
.74
.75
.81
1 .41*
1.42
1.74
1.98
1.45
1.79
1.78
1.78
1.37
.64
.74
.71
.73
PHAE
fraction
.05
.06
.03
.05
.15
.30
.28
.28
.07
.08
.06
.08
.11
.07
.04
.06
.15
.37
.30
.32
.32
SI02
mgSiO2/l
1.36
1.39
1.39
1.44
1.45
1.45
1.51
1.71
1.16
1.14
1. 19
1.23
1.27
1.31
1.30
1. 32
1.31
1.30
1.38
1.54
1.45
N03
ag S/«3
329.8
331.0
329.1
321.3
319.4
340.2
333.8
332.0
288.3
280.3
281.3
310.0
322.2
296.2
315.5
324.2
305.8
323.6
335.3
345.5
342.2
TP04
•gP/«*
3. 15
2.99
3.67
4.57
3.85
4.47
6.19
4.00
2.99
3.46
2.84
3. 15
4.66
4.94
4.53
4.82
3.32
2.15
3.19
2.27
1.42
SP04
•gP/«3
.42
1.34
1.9
-------
APPENDIX B. Primary Productivity at 5 m. Data in mgCm 3hr l
App. B.I Cruise 1, August 1973
STA
7
8
10
11
12
13
15
16
17
19
20
21
22
23
25
27
29
31
32
33
34
35
36
DEP
M
5
5
5
5
5
5
5
5
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
SAMP
28
31
49
54
60
63
71
76
79
85
9Q
93
96
100
107
119
139
158
163
167
171
179
189
C14S
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14A
PPB-C/HR
1.8
1.9
2.0
1.7
1.7
1.9
2.0
2.2
2.9
2.9
2.5
2.0
2.4
2.1
1.4
1.9
2.2
2.6
1.8
2.1
1.7
1.8
1.7
C14T
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14B
PPB-C/HR
1.7
2.7
2.0
1.7
1.5
1.8
2.1
2.1
3.3
2.6
1.8
2.6
2.2
2.3
1.3
1.8
2.5
2.4
1.7
2.0
1.6
1.8
1.5
C14D
PPB-C/HR
.15
.22
.22
.18
.31
.18
.31
.19
.32
.26
.19
.18
.17
.17
.25
.20
.24
.19
.12
.16
.09
.14
.21
ALK
PPM-C
25.2
25.2
25.8
25.4
25.7
25.5
25.4
25.9
25.8
25.8
25.9
25.2
25.6
25.9
22.6
24.2
24.6
22.9
24.2
24.2
24.6
24.6
25.2
224
-------
App. B.2 Cruise 2, September 1973
STA
1
2
3
4
5
6
7
8
9
10
11
12
14
15
16
17
18
19
22
23
24
25
26
27
28
29
30
31
38
39
40
DEP
M
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
SAMP
448
443
436
431
428
425
330
332
341
350
355
361
454
459
464
478
474
470
484
488
364
368
374
381
391
401
411
420
321
313
311
C14S
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14A
PPB-C/HR
3.1
3.0
3.1
2.9
3.0
4.2
4.5
3.9
1.7
2.6
2.1
1.8
3.0
2.6
3.2
2.5
2.3
2.8
3.8
3.6
3.0
2.4
2.5
2.2
1.7
1.6
1.6
1.5
2.2
2.7
2.2
C14T
SCREENS.
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14B
PPB-C/HR
3.2
3.2
2.9
1.8
2.8
3.9
5.4
4.3
1.8
2.5
2.4
2.1
3.5
3.0
3.0
2.2
2.1
2.6
3.2
2.4
2.9
2.4
2.8
2.0
1.9
1.7
2.0
2.3
3.0
2.6
C14D
PPB-C/HR
.24
.43
.25
.22
.36
.34
.34
.95
.18
.15
.17
.25
.29
.33
.23
.18
.38
.36
.40
.21
.17
.16
.17
.13
.14
.27
.41
.14
.17
.21
.18
ALK
PPM-C
24.6
24.0
24.1
23.7
21.3
26.6
22.9
22.4
20.5
23.7
25.3
22.1
26.5
23.3
21.5
22.9
22.9
23.1
22.9
23.8
26.3
22.6
24.1
20.9
18.8
20.3
22.1
17.5
20.7
25.0
24.0
225
-------
App. B.2 cont .
STA
41
41
42
43
44
45
46
47
48
49
50
124
130
DEP
M
5
45
5
5
5
5
5
5
5
5
5
5
5
SAMP
309
301
291
281
271
261
254
249
245
236
228
325
219
C14S
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
C14A
PPB-C/HR
2.2
-6
2.3
1.7
1.8
1.6
2.5
2.0
2.0
1.4
1.5
2.4
1.2
C14T
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
C14B
PPB-C/HR
-0
1.9
1.7
1.7
1.8
2.4
2.0
2.0
1.3
1.5
2.7
1.2
C14D
PPB-C/HR
.40
.34
.10
.10
.13
.16
.29
.11
.08
.09
.14
.16
ALK
PPM-C
22.1
22.1
19.1
17.2
21.5
20.9
21.9
17.5
16.6
17.5
20.3
21.1
21.1
226
-------
App. B.3 Cruise 3, October 1973
STA
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
28
29
30
31
DEP
M
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
SAMP C14S
SCREENS
514
509
502
497
494
491
572
575
584
593
520
517
708
711
716
721
724
727
730
735
738
741
745
748
752
757
764
774
784
794
803
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
C14A
PPB-C/HR
4.5
4.9
4.2
4.2
4.3
4.5
2.4
2.9
2.9
2.6
2.7
3.4
2.9
2.1
1.7
2.2
2.7
2.0
2.4
2.6
2.3
1.9
2.3
1.9
2.3
2.6
1.8
1.8
1.9
1.9
1.7
C14T
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14B
PPB-C/HR
3.6
3.4
2.9
2.9
2.5
6.5
.4
2.1
1.8
1.7
2.0
.4
1.8
1.9
1.5
1.9
2.1
2.5
1.5
2.7
1.6
1.9
1.7
2.0
1.7
1.6
2.4
1.7
1.7
1.3
1.4
C14D
PPB-C/HR
.46
.49
.51
.36
-45
.54
.37
.30
.18
.20
.23
.34
1.32
.37
.17
.17
.16
.27
.15
.15
.10
.12
.18
.14
.14
ALK
PPM-C
25.9
25.1
25.2
24.6
24.4
24.6
20.7
20.7
21.3
19.8
20.0
19.8
22.6
23.7
22.8
22.6
25.3
22.4
22.3
20.3
20.3
22.8
24.0
20.5
19.1
19.1
18.6
17.2
17.8
17.2
17.5
227
-------
App. B.3 cont.
STA
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
124
130
DEP
M
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
SAMP
568
564
556
546
536
526
700
692
690
680
670
660
650
640
633
628
624
615
607
704
598
C14S
SCREENS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
C14A
PPB-C/HR
3.4
3.7
3.2
3.7
3.3
3.4
3.8
2.3
2.1
1.5
1.8
2.2
2.6
3.0
1.9
2.6
2.6
2.1
2.1
3.1
2.0
C14T
SCREENS
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
C14B
PPB-C/HR
2.4
2.5
2.2
2.1
2.6
3.0
1.7
1.5
1.6
.5
1.9
2.7
1.7
2.2
1.4
2.1
2.0
2.4
1.6
1.6
1.3
C14D
PPB-C/HR
.44
.33
.35
.26
.27
.36
.21
.29
1.00
.30
.50
.27
.29
.19
.14
ALK
PPM-C
18.8
19.1
18.8
19.8
20.0
21.3
21.9
19.1
22.1
19.6
20.3
18.8
19.3
24.5
17.5
16.0
14.2
16.9
18.0
21.1
18.0
228
-------
APPENDIX C. Depth profiles of north-south transects
Appendix C.I Transect 01-06, Cruise 1, August 1973
02 01
CECIL BAY
Silica
Appendix C.2 Transect 01-06, Cruise 2, September 1973
WEST OF
GROS CAP
CECIL BAY
06
05
04
03
'
02 01
i *
--\ ' \
/"
16
Temp.
Silica
KILOMETERS
229
-------
Appendix C.3 Transect 01-06, Cruise 3, October 1973
CECIL DAY
Silica
KILOMETERS
230
-------
S3
OJ
App. C.4
Transect 07-10, Cruise 1
August 1973
RABBIT'S BACK PEAK
07
MACKINAC ISLAND
Temp .
App. C.5
Transect 07-10, Cruise 2
September 1973
RABBIT'S BACK PEAK
MACKINAC ISLAND
Temp.
KILOMETERS
App. C.6
Transect 07-10, Cruise 3
October 1973
RABB'T'S BACK PEAK
07 OjB
MACKINAC ISLAND
Temp.
KILOMETERS
KILOMETERS
-------
App. C.7 Transect 13-16, Cruise 1, Aug. 1973
SOUTH OF LIME KILN POINT
BOIS BLANC ISLAND
rO
WEST OF
POINT AU SABLE
Temp.
KILOMETERS
App. C.8 Transect 13-16, Cruise 2, Sept. 1973
SOUTH OF LIME KILN POINT
BOIS BLANC ISLAND
r°
-10
-zo
-0
i-to
-20
-0
-10
L-zo
0
10
L-20
WEST OF
POINT AU SABLE
Temp.
KILOMETERS
232
-------
App. C.9 Transect 13-16, Cruise 3, Oct. 1973
SOUTH OF LIME KILN POINT
BOIS BLANC ISLAND
WEST OF
POINT AU SABLE
Temp.
KILOMETERS
App. C.10 Transect 17-23, Cruise 1, August 1973
MIDWAY BETWEEN ZELA POINT
AND PT. AUX PINS, BOIS BLANC ISLAND
20 19 18
-0
-10
-20
-o
-10
-20
-0
-10
-20
-0
-10
-20
EAST OF
CHEBOYGAN
Temp.
PACKARD POINT
BOIS BLANC ISLAND
21 22
Spec.
Conduct.
Silica
EAST OF
CHEBOYGAN POINT
Temp.
Spec.
Conduct.
Silica
KILOMETERS
233
-------
App. C.ll Transect 17-23, Cruise 2, September 1973
MIDWAY B!
AND PT AUX PINS, BOIS BLANC ISLAND
20 19 18 17
__.J 1 L
ho
L-ZO
rO
-10
-20
-0
-10
-20
-0
-10
-20
EAS- IF
PACKARD POINT
CHEBOYGAN &0|S SLANG ISLAND
21 22
J rO '
Temp.
Spec.
Conduct.
Silica
23
CHEBOYGAN POINT
Temp.
U20
Spec.
Conduct.
Silica
KILOMETERS
App. C.12 Transect 17-23, Cruise 3, October 1973
MIDWAY BETWEEN ZELA POINT
AND PT. AUX PINS, BOIS BLANC ISLAND
2O 19 18
EAST OF
CHEBOYGAN
Temp.
Spec.
Conduct.
Silica
PACKARD POINT
BOIS BLANC ISLAND
21 22
EAST OF
CHEBOYGAN POINT
Temp.
Spec.
Conduct.
Silica
KILOMETERS
234
-------
App. C.13 Transect 24-31, Crutse 1, August 1973
GOVERNMENT
ISLAND
EAST OF
CORDWOOD POiNT
Temp.
Spec.
Conduct.
Silica
KILOMETERS
235
-------
App. C.14 Transect 24-31, Cruise 2, September 1973
GOVERNMENT
ISLAND
EAST OF
CORDWOOO POINT
Silica
KILOMETERS
236
-------
App. C.15 Transect 24-31, Cruise 3, October 1973
GOVERNMENT
ISLAND
EAST OF
CORDWOOD POINT
Spec.
Conduct.
Silica
KILOMETERS
237
-------
ho
LO
CO
App. C.16
Transect 32-37, Cruise 1, August 1973
SEARCH BAY
POINT DETACHEE
BOIS BLANC ISLAND
IO
20
30 Spec.
«« Conduct.
App. C.17
Transect 32-37, Cruise 3, October 1973
SEARCH SAY
POINT DETACMEE
BOIS BLANC ISLAND
Spec.
;40 Conduct.
i. SO
-------
App. C.18 Transect 40-48, Cruise 2, September 1973
POINT DETOUR
FORTY MILE
OJ
Temp.
POINT DETOUR
FORTY MILE POINT
42 41 401
Spec.
Conduct.
pH
Silica
-------
App. C.19 Transect 40-48, Cruise 3, October 1973
KJ
*-
o
43
FORTY MILE POINT
4Z 41 40
POINT DETOUR
FORTY MILE POINT
Temp.
Spec.
Conduct.
Silica
-------
APPENDIX D
List of species found in phytoplankton collections
BACILLARIOPHYTA
Achnanthes affinis Grun.
A. biasolettiana (Kutz.) Grun.
A. clevei Grun.
A. clevei var. rostrata Hust.
A. exiqua Grun.
A. exigua var. constricta (Grun.) Hust.
A. exigua var. heterovalva Krasske
A. lanceolata (Breb.) Grun.
A. lanceolata var. dubia Grun.
A. lanceolata var. omissa Reim.
A. laterostrata Hust.
A. linearis (Wm. Smith) Grun.
A. linearis fo. curta H. L. Smith
A. microcephala (Kutz.) Grun.
A. minutissima Kutz.
A. minutissima var. cryptocephala Grun.
A. peragalli Brun
A. pinnata Hust.
A. subsaloides Hust.
Species incertae sedis
Achnanthes questionable sp. #1
Achnanthes sp. #1
Achnanthes sp. #15
Achnanthes sp. #28
Amphipleura pellucida Kutz.
Amphiprora ornata Baily
Amphora hemicycla Stoerm. and Yang
A. ovalis var. libyca (Ehr.^( Cleve
A. ovalis var. pediculus (Kutz.) V. H.
A. ovalis Kutz.
A. veneta var. capitata Haworth
Species incertae sedis
Amphora questionable sp. #1
241
-------
App. D cont.
Anowoeoneis vitrea (Grun.) Ross
Species incertae sedis
Anomoeoneis vitrea var. #1 (abnormal)
Anomoeoneis sp. #3
Asterionella formosa Mass.
Caloneis alpestris (Grun.) Cleve
Species incertae sedis
Caloneis ventricosa var. #2
Cocconeis diminuta Pant.
C. pediculus Ehr.
C. placentula Ehr.
C. placentula var. euglypta (Ehr.) Cleve
C. placentula var. lineata (Ehr.) V. H.
Species incertae sedis
Cocconeis questionable sp. #1
Cocconeis sp. #4
Cyclotella antiqua Wm. Smith
C. atomus Hust.
C. comensis Grun.
C. comta (Ehr.) Kutz.
C. cryptica Reimann, Lewin, and Guillard
C. kuetzingiana Thwaites
C. kuetzingiana var. planetophora Fricke
C. kuetzingiana var. radiosa Fricke
C. weneghiniana Kutz.
C. meneghiniana var. plana Fricke
C. michiganiana Skv.
C. ocellata Pant.
C. opercu-Zata (Agardh) Kutz.
C. stelligera (Cleve and Grun.) V. H.
Species incertae sedis
Cyclotella comta auxospore
Cyclotella stelligera auxospore
Cyclotella sp. auxospore
Cyclotella sp. #5
Cyclotella sp. #7
Cymatopleura solea (Breb. and Godey) Wm. Smith
242
-------
App. D cont.
Cymbella cesatii Grun.
C. cistula (Ehr.) Kirchn.
C. cistula var. gibbosa J. Brim
C. delicatula Kutz.
C. hustedtii Krasske
C. leptoceros var. rostrata Hust.
C. microcephala Grun.
C. minuta Kutz.
ii
C. obtusiuscula Kutz.
C. parvula Krasske
C. prostrata (Berk.) Cleve
C. subventricosa Cholnoky
C. triangulata (Ehr.) Cleve
Species incertae sedis
Cymbella questionable sp. #1
Cymbella sp. #15
Cymbella sp. #21
Denticula tenuis var. crassula (Naeg.) Hust.
Diatoma tenue var. elongatum Lyngb.
Diploneis boldtiana Cleve
D. elliptica var. pygmaea A. Cl.
D. oculata (Breb-) Cleve
D. parma Cleve
Species incertae sedis
Diploneis sp. #2
Epithenda smithii Carruthers
Eucocconeis flexella (Kutz.) Hust.
E. flexella var:. alpestris (Brun) Hust.
E- lapponica Hust.
Eunotia exigua (Breb.) Rabh.
E. incisa Win. Smith
E. praerupta var. inflata Grun.
Fragularia brevistriata Grun.
F. brevistriata var. inflata (Pant.) Hust.
F. capucina Desm.
F. construens (Ehr.) Grun.
F. construens var. minuta Temp, and Per.
F. construens var. pumila Grun.
F. construens var. venter (Ehr.) Grun.
243
-------
App. D cont.
Fragilaria crotonensis Kitton
F. crotonensis var. oregona Sov-
F. intermedia Grun.
F. intermedia var. fallax Grun.
F. lapponica Grun.
F. leptostauron (Ehr.) Hust.
F. leptostauron var. dubia (Grun.) Hust.
F. pinnata Ehr.
F. pinnata var. intercedens (Grun.) Hust.
F. pinnata var. lancettula (Schum.) Hust.
F. vaucheriae (Kutz.) Peters
F. vaucheriae var. capitellata (Grun.) Patr.
F. vaucheriae var. lanceolata A. Mayer
Species incertae sedis
Fragilaria questionable sp. #1
Fragilaria crotonensis Kitton (abnormal)
Frustulia rhomboides var. amphipleuroides (Grun.) Cleve
Gomphonema intricatum Kutz.
G. intricatum var. pumila Grun.
G. lanceolatum Ehr.
Species incertae sedis
Gomphonema questionable sp. #1
Gyrosigma attenuatum (Kutz.) Rabh.
G. spencerii (Quek.) Griff, and Henfr.
Hannaea arcus (Ehr.) Patr.
Mastogloia grevillei Win. Smith
Melosira distans var. alpigena Grun.
Af. granulata (Ehr.) Ralf s.
Af. granulata var. angustissima 0. Mull.
Af. islandica 0. Mull.
Af. italica subsp. subartica 0. Mull.
Navicula anglica var. subsalsa (Grun.) Cleve
N- aurora Sov.
N- capitata Ehr.
N. capsa Hohn
N. cryptocephala Kutz.
N. cryptocephala var. veneta (Kutz.) Rabh.
N. decussis 0str.
N. exigua Greg. ex. Grun.
244
-------
App. D cont.
Navicula lacustris Greg.
N. lanceolata (Agardh) Kutz.
N. minima Grim.
N. nyassensis 0. Mull.
N. placentula var. rostrata A. Mayer
N. pseudoscutiformis Bust.
N. pupula Kiitz.
N. radiosa Kutz.
N. radiosa var. parva Wallace
N. radiosa var. tenella (Breb.) Grun.
N. rhunchocephala Kutz.
ff- stroesei A. Cl.
N- tuscula fo. obtusa Hust.
N. vulpina Kutz.
Species incertae sedis
Navicula questionable sp. #1
Navicula sp. #1
Navicula sp. #12
Navicula sp. #35
Neidium dubium fo. constrictum Hust.
Nitzschia acicularis (Kutz.) Win. Smith
N. acuta Hantz.
N. amphibia Grun.
N. angustata var. acuta Grun.
N. bacata Hust.
N. capitellata Hust.
N. con finis Hust.
N. denticula Grun.
N. dissipata (Kutz.) Grun.
N. dissipata var. media (Hantz.) Grun.
N. fonticola Grun.
IV. insecta Hust.
N. luzonensis Hust.
N. palea (Kutz.) Wm. Smith
N. recta Hantz.
N. sigma (Kutz.) Wm. Smith
N. sigmoidea (Nitz.) Wm. Smith
N. spiculoides Hust.
N. sublinearis Hust.
Species incertae sedis
Nitzschia questionable sp. #1
Nitzschia sp. #2
Nitzschia sp. #6
245
-------
App. D cont.
Nitzschia sp. #8
Nitzschia sp. #9
Nitzschia sp. #10
Nitzschia sp. #12
Opephora martyi Herib.
Rhizosolenia eriensis H. L. Smith
R. gracilis H. L. Smith
Rhoicosphenia curvata (Kutz.) Grun.
Stephanodiscus alpinus Hust. ex Huber-Pestalozzi
S. astraea (Ehr.) Grun.
5. hantzschii Grun.
S. minutus Grun. ex Cleve and Moll.
S. niagarae Ehr.
S. niagarae var. magnifies Fricke
S. subtilis (Van Goor) A. Cl.
S. tenuis Hust.
Species incertae sedis
Stephanodiscus sp. #5
Stephanodiscus sp. auxospore
Surirella biseriata Breb. and Godey
S. ovata Kutz.
Species incertae sedis
Surirella sp. #4
Synedra acus Kutz.
S. cyclopum Brutschy
S. delicatissima var. angustissima Grun.
S. demerarae Grun.
S. filiformis Grun.
S. minuscula Grun.
S. wontana Krasske
5. ostenfeldii (Krieger) A. Cl.
S. parasitica (Wm. Smith) Hust.
5. parasitica var. subconstricta (Grun.) Hust.
S. tenera Wm. Smith
5. ulna (Nitz.) Ehr.
S. ulna var. chaseana Thomas
5. ulna var. danica (Kutz.) V. H.
S. ulna var. longissima (Wm. Smith) Brun
246
-------
App . D cont.
Species incertae sedis
Synedra questionable sp. #1
Synedra sp. #7
Synedra sp. #17
Tabellaria fenestrata (Lyngb.) Kutz.
T. fenestrata var. geniculata A. Cl.
T. fenestrata var. intermedia Grun.
T. flocculosa (Roth) Kutz.
CHLOROPHYTA
Ankistrodesmus gelifactum (Chod.) Bourr.
Botryococcus braunii Kutz.
Coelastrum microporum Naeg.
Cosmarium botrytis Menegh.
Crucigenia irregularis Wille
C. guadrata Morren
Eudorina elegans Ehr.
Franceia droescheri (Lemm.) G. M. Smith
Gloeocystis planctonica (W. and W.) Lemm.
Golenkinia radiata (Chod.) Wille
Lagerheimia ciliata (Lag.) Chod.
Nephrocytium agardhianum Naeg.
Pediastrum boryanum (Turp.) Menegh.
Quadrigula chodatii (Tan.-Ful.) G. M. Smith
Q. lacustris (Chod.) G. M. Smith
Scenedesmus arcuatus Lemm.
S. armatus (Chod.) G. M. Smith
S. bijuga (Turp.) Lag.
5. bijuga var. alternans (Reinsch) Hansg.
S. helveticus Chod.
S. guadricauda (Turp.) Breb.
S. serratus (Chod.) Bohl.
Sphaerocystis schroeteri Chod.
Spondylosium planum (Wolle) W. and W.
Staurastrum paradoxum Meyen
S. paradoxum var. biradiatum (W. and W.) Griffiths
S. longipes (Nordst.)((Teiling
Tetraedron regulare Kutz.
Ulothrix subconstricta G. S. West
Species incertae sedis
Ankistrodesmus sp. #1
Ankistrodesmus sp. #2
Ankistrodesmus sp. #3
247
-------
App. D cont.
#1
Ankistrodesmus sp. #4
Cosmarium sp. #1
Cosmarium sp. #2
Eutetrairorus questionable sp. #1
Gloeocystis questionable sp. #1
Oocystis spp.
Staurastrum sp. #2
Undetermined green colony
Undetermined green colony questionable sp.
Undetermined green filament #2
Undetermined green filament #3
Undetermined green individual
CHRYSOPHYTA
Chrysococcus (dokidophorus Pasch.?)
Chrysosphaerella longispina Lautb.
Dinobryon bavaricum Imhof
D. cylindricum Imhof
D. divergens Imhof
D. sociale Imhof
Mallomonas pseudocoronata Presc.
M. tonsurata var. alpina (Pasch. and Ruttn.) Krieger
Species incertae sedis
Chrysophyte cyst
Dinobryon cysts
Dinobryon questionable sp. #1
Mallomonas questionable sp. #1
CRYPTOPHYTA
Cryptomonas ovata Ehr.
Rhodomonas minuta var. nannoplanctica Skuja
Species incertae sedis
Cryptowonas cyst
248
-------
App. D cont.
CYANOPHYTA
Anabaena flos-aquae (Lyngb.) Breb .
Anacystis incerta (Lemm.) Dr. and Daily
A. thermal is (Menegh.) Dr. and Daily
Gomphosphaeria lacustris Chod.
Oscillatoria bornetii Zukal
PYRROPHYTA
Ceratium hirundinella (0. F. Mull.) Shrank
Peridinium cinctum (0. F. Mull.) Ehr.
Species incertae sedis
Peridinium questionable sp. #1
249
-------
APPENDIX E
Proof that a conservative parameter can be expressed
as a linear combination of other conservative parameters
Definition: A conservative parameter is defined as one which has a
measured value y in a mixture of volumes V± from N different sources,
such that:
N N
i) y = E V± Y± = I F± Y±
1=1 i=l
N
AVJ
and where Y^ = measured value of the conservative parameter at source i_
Vn-
i
and F,- = —- = the fraction of water in the final mixture
N ,
v from source i
L \/ • —
3=1 J
To show: If Y is a conservative parameter, then it is expressable as a
linear combination of any two other conservative parameters T and C in
a mixture of water from three water sources.
Proof: For convenience, rewrite eq. i using vector notation:*
ii) y = F • Y
where F = (Fj, F2, ... , FJJ) = the vector of fractions
Y = (Yls Y2, ... , YN) = the vector of values of Y at the
sources
N = the number of sources = 3, for this case.
Write eq. ii for each of the three conservative parameters:
iii) t = F • T
iv) c = F • C
v) y = F • f
* This proof uses terminology from linear algebra. Refer to any standard
text on that subject.
250
-------
N
E Vi
N 1=1
Note that: I F^ = — = 1, or:
1=1 Z V-i
3=1 J
vi) F • G = 1 where G = (1,1,1)
We must now^make two requirements on f and C. First, it is necessary
that T and C are independent of each other. This is a logical require-
ment, since if they are not independent, then they are proportional and
consequently redundant. Examples of non-independent variables are the
concentrations of dissolved nitrate in ppm and yg at/1 or, in most cases,
the concentrations of Na+ and Cl . Second, it is necessary that T and C
both be independent of G. This is also a logical requirement. Any
parameter not fulfilling this requirement will have the same value at all
the sources, thus^will be useless as a tracer. If these two requirements
are met, then T, C, and G are mutually independent and are thus a basis
for all three-dimensional^yectors. Consequently, Y is expressable as a
linear combination of T, C, and G:
vii) Y = BT + yC + aG
Combining eq. v with eq. vii:
v) y = Y • F
= (gf + yC + aG) • F
= BT-F" + yC-F" + a£-?
viii) y=8t+yc+a
Equation viii shows that any conservative parameter y can be expressed
as a linear combination of any two other independent, non-uniform conser-
vative parameters if there are exactly three sources. By a simple exten-
sion of this argument, it can be shown that:
If there are N sources, then any conservative parameter (as
defined in eq. i or ii) can be expressed as a linear combina-
tion of N-l other conservative parameters which are neither
uniform at all the sources nor proportional to each other
(dependent).
Implicit in this discussion is the assumption that the values of the
parameters at the sources do not change with time.
251
-------
APPENDIX F. Counts of zooplankton from vertical net tows
Appendix F.I
Cruise: 1
ho
Ui
NJ
Srat ion :
Date:
Tow length
in meters:
Species:
Calanoid Copepoda
D ash
D min
D oreg
D siclis
D cops
E lac
L raai
S cal
Cyc 1 opoid Copepoda
C bi th
M edax
r pr mex
Cladocera
L kind
P ped
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
L quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lamell
Clad imm.
Calan Tot (#/m '')
Calan Tot (%)
Cyclo Tot (#/m'l
Cyclo Tot (Z)
Clad Tot (0/tn1)
Clad Tot (%)
Grand Total
1A*
AUK 30
I4«S
60
318
286
481
127
74
71
25
923
3325
11
2638
14
67
608
156
1272
13.9
74
0.8
7838
85.3
9184
'B
Aug 30
14 -S
42
111
481
14
523
141
„ )
W
28
905
3282
2900
28
1047
141
iil2
15.2
43
0.4
8388
84.4
9943
?A
Aug 3D
21 -S
27
1626
661
509
116
259
71
9
956
2127
1653
9
27
688
29)9
33 .h
759
).()
5540
6J.4
8738
2B
Aug 30
21 -S
67
1282
482
661
107
183
2/
18
13
916
1805
1372
18
58
634
2599
34.0
183
2.4
4861
(Vt.6
7643
i
Aug fn
40*20
7S
76
908
700
437
149
233
4?
8
1146
1732
1439
620
•140
2270
29.fi
233
3.1
5127
67.2
7630
4A
Aug 30
2j-s
49
752
352
18
879
JO
206
6
11 >
42
740
1316
424
576
6
6
6
418
127
2080
34.3
212
3.5
3776
62.2
6068
4B
Aug 30
23-S
89
857
364
1496
40
243
89
89
1059
1655
32
558
24
8
8
493
121
2846
39.4
243
3.4
4136
57.2
7225
5A
Aug 30
]fr*s
194
800
715
1225
97
800
109
1395
2583
133
2365
24
24
667
182
3031
26.8
800
7.1
7482
66.1
11313
5B
Aug JO
16>S
155
543
791
858
39
673
100
12
897
1804
21
1831
9
9
491
340
2386
27.8
673
7.9
5514
64.3
8573
h
Aug 10
12-S
12
38
22
79
13
40
32
103
374
37
684
23
93
9
164
10.5
40
2.6
1355
86.9
1559
i
Aug id
14 -s
369
72
396
3824
S ')
572
8
44
8
641
760
1221
796
24
158
303
127
4716
50.3
580
6.2
4082
43.5
9378
8
AUK 20
23-5
1.84
57
4
6] 64
10
M
950
4
(,
30
313
1251
170
12
99
89
6427
68.7
954
10.2
1970
21.1
9351
8
Aug (U
21-11
32h
41
35/
10
12844
31
1 /X 4
Id
TO
41
509
2210
275
102
132
295
13609
71 . /
1793
9.4
3584
18.9
18986
*Stations 1 2, 4, and 5 were samplf) rwic*' during the same day. These samples are designated as "A" and "B".
-------
App . F.I con t.
Cru tse: 1
Station:
Date-
Tow length
in meters:
Species'
r-alarxoiu t.opepacU.
i> ,sh
1) min
l) oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Cl adorers
L Hi u.i
1* ped
1) leuch
S rrysl
H g«,
D gal rot
D long
B retro
'.: lac-
L quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
r .sphaur
E lamell
Clad turn.
. !an I'm 1 tf !m "j
i.alan Tol C/.}
oyrlo Col (*/m
C.yrlo CM 1 Z>
Clad Tot (ff/m')
Clad Tot (%)
Grand Total
8
Aug 30
11 >s
241
311
990
1103
85
140
5?
4i
1825
2660
1500
1740
28
170
806
523
2710
22. (j
)40
f . i
9351
75.3
12421
9
VuK SI
JVIb
:t
23
23
20
4510
3
91
3
659
17
111
1)9
45
37
40
14
,MH
81 .
659
11
385
6.
5740
9
Aug !0
I6>-S
21,'
212
424
1380
42
255
i,;
It
817
2165
64
1 Ml
1 1
74
363
26',
J - .
' S >
1
5051
.7 66.
7576
10
Aug 111
23-S
IT'
2S9
441
1164
101
12
719
8
H'i
hi
1091
1 90'.
53
1382
8
97
812
174
•1 1 1 0
a 24 «
. J >
.It 8. i
5667
.7 66.6
8504
H
AuS 10
>9>L '
315
12
I7b
8106
1667
12
1?
18
29;
>553
509
1140
49
103
491
88HV
56.3
1679
10. '
5172
33.0
15660
11
Aug 30
1 )>S
85
116
224
416
54
54
17
39
4244
903
15
370
77
1215
?31
895
11.0
•)H
'J . "'
7191
88.3
8140
11
Sep 1
29, If
90
M
1 74
5929
3
722
9
9
i
79
422
45V
321
9
15
78
106
h279
'3
'3i
8.b
1505
17.7
8515
11
Sep 1
Ib-t,
l ><'
HOO
703
1091
267
145
55
24
1589
2534
321
.1116
30
103
1801
327
nu i
'6.3
34^
l.ii
8100
70.7
11458
12
Aug 10
13-»S
79
771
220
557
50
205
61
.)/
8
1685
1951
174
835
16
5
71
1050
6
19
167/
?] .
205
2.6
5920
75.9
7802
13
Sep 1
19->S
110
1388
679
479
130
260
10
70
60
40
979
2317
260
769
II)
40
379
200
27S6
34.1
,,/D
3. 1
5124
62.6
8180
14
Sep 1
25-M9
534
80
1670
7639
46
45
1577
12
43
1 1
410
2081
2254
1227
11
67
694
666
10014
52.5
1589
83
7464
39.1
19067
14
Sep 1
|9>S
27
627
2 ft*
236
32
134
5
70
21
1 1
1238
777
80
306
1 1
16
343
118
1 1 90
2/.5
139
3.2
2991
69.2
4320
15
Sep 1
25-S
199
347
694
L535
81
7
421
66
15
1107
201(1
760
827
7
66
893
362
28b3
30.4
421
4 . 1
6133
65.1
9417
16
Sep i
22-»S
95
47J
484
8
1286
115
225
8
47
13
21
1536
2220
225
1197
8
21
581
140
2457
28.2
233
2. /
6009
69.1
8699
17
Sep 1
IU-S
)2
435
12
350
64
106
11
)2
i i
1517
21 3J
223
573
11
32
828
3?
91*
14.?
1
'. .1
539.'
84.0
6422
18
Sep !
l'v>S
1>9
1166
500
686
176
196
29
'4.!
• ; c,
i . >
74'!..'
72.7
10)04
-------
App. F.I cent.
Cruise: 1
Station:
Date:
Tow length
in meters'
Species:
Oalanoid Copepoda
D ash
D min
P oreg
D slclis
0 cops
t lac
1 mac
S cal
Cvclopoid Copepoda
C bi th
M edax
T pr tnex
f'tadorera
1 kind
r ped
.' leuch
S cryst
H gib
\i gal me
D long
n ret rn
C !*<•.
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
(' sphaci
E lanell
Clad imm.
ualan lot (H/m ,
Calan T<-t CZ)
i.yclo Tot (#/-.': ;
Cyc].) Tot (%>
Clad Tot (#/m3)
Clad Tot (%)
Grand Total
19
Sep 1
24>S
54
532
652
660
139
448
58
39
8
tfhK
195V
166
> 192
8
23
799
185
203 /
26.2
448
s.s
5298
68.1
7783
20
Sep 1
20>S
127
434
1306
1151
184
307
9
33
9
28
1523
2268
585
12SH
14
9
707
373
320/
31.0
316
>. i
6799
65.9
10317
21
Sep 1
16 .-i
182
543
800
2665
115
543
33
18
18
30
1379
1807
382
882
9
12
52
825
179
4305
41 1
576
5.5
5593
53.4
10474
22
Sep 1
19. s
1H
22-
136
701
108
264
72
54
6
6
917
1101
240
491
24
515
6
1385
27 j
Mb
h.6
3361
66.1
5082
23
Sep 1
16>S
i6
73
119
3
671
83
169
13
4'!
^
562
625
13
311
10
13
268
40
i DOS
32.7
IR2
.5. *)
1885
61.4
3072
24
Aug 31
17 >S
124
498
141
1228
62
130
17
4 j
62
97)
979
45
549
28
843
79
2053
35 4
147
;..>
3603
62.1
5803
25
Aug 31
i* 15
193
45
1.57
8
8172
12
61
1022
17
'.
S
Z47
1105
376
26f>
27
171
139
8648
'1.9
1039
8.6
2343
19.5
12030
25
Aug 31
L5>S
to
145
79
781
116
116
65
54
65
25
?02
L171
399
6
82
487
68
1361
29 6
181
3.9
3059
66.5
4601
26
Aug 31
32. -15
16]
37
123
22
9155
6
67
726
10
37
D
141
605
83
176
4
23
116
96
957J
«2.5
736
6. j
1295
11.2
11602
26
Aug 31
15-S
51
1019
306
611
102
136
17
25
59
25
1757
1528
17
331
17
34
197
161
208 1
i: .;
153
. •<*
4151
64.9
6393
27
Aug 11
51 -1
91
4
102
4035
182
14
511
8
'~_,
1
12 )
335
306
140
19
52
22
=4428
'4.4
a 9
3 ,
1003
16.9
5950
27
Aug )l
17-»S
157
397
315
906
82
502
7
' L
1378
936
225
472.
52
502
/: 7
1857
10 .
i09
rf.V
3804
61.7
6170
28
Aug 31
58 '1 '.
34
9
16
10
15706
1
74
9
171
I
2f>
130
118
48
20
65
4;
ljb',9
96.2
1 71
1 ,0
452
2.7
16482
28
Aug »l
IV'S
15H
622
260
1063
158
622
11
:>/
'3
. i
1709
1347
136
396
102
521
373
2261
29.8
633
8. i
4687
61.8
7581
29
Aug II
6HM5
44
9
24
9
3017
1
28
185
1
;
1
34
254
183
93
51
63
16
313*
77.6
1K5
'• 1:
718
17.8
4035
29
Aug 11
1 5->S
167
419
21)9
1647
139
42
100
2.1
•JLH)
IJ 32
4?4
">K')
110
928
21P
2623
34. /
300
4.0
4641
61.4
7564
-------
App. F.I cont.
Cruise: 1
Station.
Date:
Tow length
in meters:
Species:
Calanoid Copepoda
D ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cvclopoid Copepoda
C bi th
M edax
T pr mex
Cladoi'era
I- Kind
S 'P*
(_n D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A narp
A affin
A quad
sphaer
F 1 ame i 1
Clad imm.
Calan Tot (///m1)
CaJan Tot (%)
Cyclo Tol ("/m1 )
Cyclo Tol (%)
Clad T'.| (II /a' I
Clml Tot (/)
(irand Total
31'
Aug 31
44->ll
115
25
99
21
6863
21
41
748
8
2.1
12
288
661
567
329
181
90
107
7185
70.
756
7.
2256
22
10197
30
Aug 31
11 »S
194
167
417
6=5
85.'
130
370
9
2H
56
1982
1769
556
1157
28
278
1028
1 76
1825
.5 19.
)79
.4 4.
7f)'i«
. 1 /h.
92hP
51
Aug VI
26*11
509
39
470
39
17068
1946
39
13
39
457
2377
2338
1450
24K
26]
,f>
18125
7 65.2
1985
.1 7.1
7705
.2 27.
/HI',
H
Aug 31
ll+S
142
574
336
1535
37
15
732
9
28
77
52
1858
2337
151
1602
404
J44"i
?62
2639
22.8
741
6.4
821(,
70.9
, 1 596
32
Aug 31
23^11
511
196
38
21413
17
995
/
15
836
1238
283
20
•nt
.-'81
22175
85. 7
995
J.K
'700
10.4
^'lX''(:
32
Aug U
1] 'S
93
247
302
9
1803
117
787
15
34
15
56
1324
1843
710
1688
15
41;
1219
33b
2571
23.3
802
7.1
'657
69.4
1 lino
33
Aug 31
23>11
560
51
373
14854
1511
1.7
340
1630
2801
662
323
I5.i
106
15838
67.2
1528
b.5
f.21')
26.4
- i:)8i
3J
Aug 31
11*S
93
240
266
942
245
256
18
23
30
1397
974
359
873
55
336
642
159
1786
25.9
274
4.0
4848
70.2
6908
34
Aug 31
38*27
2
8
4
1934
2
19
300
2
3
23
67
43
22
J2
33
10
1969
86.2
100
4.4
215
9.4
2284
it,
Aug 31
11->S
102
325
174
718
108
5
301
20
24
28
1420
896
314
725
5
216
517
76
1432
24.0
J21
5.4
4221
70.7
5974
3b
Aug 31
29
5
12
28
2573
5
39
219
4
48
40
52
18
26
31
5
2662
85.7
219
7.]
224
7.2
1105
35
Aug 31
11>S
147
249
411
12
2211
46
12
515
12
23
h
12
955
961
1065
642
6
197
336
104
3088
39.0
527
6.7
4307
54.4
7922
36
Aug 3J
49*11
120
59
212
35
3299
73
21
321
J5
2
252
495
457
354
5
35
125
87
3819
63.8
321
5.4
1847
30.9
5987
3o
Aug 31
1 1 >S
51
370
597
42
1273
162
185
9
3/
79
991
1792
607
1699
9
9
181
634
185
2495
28.0
194
2.2
h223
69.8
89J2
37
Aug 31
47->13
134
14
65
1]
5211
8
29
3
562
3
S
1
100
326
485
261
8
3
40
67
89
4475
69.6
565
8.8
1390
21 .6
6430
37
Aug 31
n>s
47
235
118
466
161
262
1 , ,
V<
1826
1626
423
1105
98
846
208
1027
13.6
262
3.5
6285
S3. (I
7574
-------
Appendix F.2
Cruise: 2
Slat ion .
Datt- :
Tow length
in meters:
Spec i e s :
Calnnoid Copepoda
D ash
D min
D oreg
D siclis
D cops
E lac
L mac.
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Cladoi era
1, kind
I' pi'd
D leuch
S t-ryst
H gib
D gal me
D long
D re t ro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lamell
Clad imm.
Calan Tot (#/mf)
Calan Tot (Z)
Cyclo Tot (tf/m3)
Cyclo Tot ('/.)
Clad Tot (#/m3)
Clad Tot (%)
Grand Total
I
Sep 19
16-S
2 j
113
651
221
138
80
98
258
3660
15
1262
182
95
1148
16.9
80
1.2
5570
81.9
6798
-i
Sep 19
22 >S
34
76
433
187
25
34
51
204
1485
59
416
59
17
755
24.8
34
1.1
2291
75.2
3046
3
Sep 19
53-S
10
206
3
250
50
7
3
27
63
786
30
353
3
3
3
23
63
5?6
27.9
3
0.2
1354
71.9
1883
4
Sep 19
19-i-S
35
20
205
649
50
75
75
114)
72
379
40
80
2842
60.4
75
1.6
1787
38.0
4704
5
Sep 19
U-S
43
19
272
693
39
69
14
8
79
949
191
461
43
114
1066
35.6
69
2.3
1859
62.1
2994
6
Spp 19
12->S
,j
5
389
556
9
5
185
19
5
6r>
19
56
1181
301
509
5
5
28
14
14
51
1015
29.2
209
6.0
2248
64.7
3472
7
Sep 18
14-^S
19
19
40
2
1384
21
32
89
4
17
?
45
359
125
229
2
4
13
2
1517
63.0
93
3.9
798
33.1
2408
8
Sep 18
28>S
13
14
56
390
46
23
22
9
145
447
23
212
9
15
44
519
35.4
23
1.6
926
63.1
1468
9
Sep 18
41 *S
b
10
87
11
439
29
17
10
1
1
1
34
310
94
174
4
30
25
599
46. /
to
0.8
674
52.5
1283
11
Sep 18
il >S
36
164
187
9
2477
70
6
899
2l»
138
702
252
395
6
59
59
135
2969
52.7
899
16.0
1766
31.3
5634
12
Sep 18
15>S
274
86
313
8
1661
251
8
533
2/i
133
1598
157
721
47
78
2601
40.5
533
8.3
2758
42.9
6425
14
Sep 19
25^5
31
85
168
402
57
30
13
33
6
271
1628
207
664
98
164
743
19.3
43
1.1
3071
79.6
3857
15
Sep 19
26 >S
7
42
99
1
184
92
67
1?
276
1206
78
393
110
78
431
16. i
67
2.5
2173
81.4
2671
1 b
Sop 19
21 -S
7
47
214
107
65
87
18
21
l>
152
1342
56
480
107
83
440
15.7
105
3.7
2258
80.6
2803
-------
App. F.2 cont.
Cruise: 2
NJ
Station:
Date:
Tow length
in meters:
Spei les:
Calano i >, f.opepoda
D ash
D min
1) oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Ciadocera
1 kind
peil
n leuch
S cryst
H gib
D gal me
D long
D retro
'.' lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
' sphaer
F lamell
Clad imm.
Calan Tot (#/tn''l
Calau TOL (7,)
Cyclo Tot (#/m ')
Cvc lo Tot (%)
Clad Tot (0/m')
Clad Tot (%)
Grand Total
17
Sep 19
9>S
23
26
153
4
428
167
57
31
8
46
757
125
728
7
80
80
HOI
29.
57
?
1862
68.
2720
18
Sep 19
15-+S
44
94
120
344
109
87
33
65
H3H
159
470
1
65
48
71 I
n /$.
8;
1 1.
1679
.5 67.
2477
19
Sep 19
24->S
6
46
140
3
334
50
4
31
25
4
46
631
106
28h
34
19
583
7 3J.O
31
1 .8
1151
,8 65.2
1765
22
Sep 19
18*S
32
199
477
103
88
8
H
8
167
1464
111
493
103
103
8H
""<•. j
96
4
2457
73.0
3364
23
Sep 19
17»S
34
47
195
297
115
64
4
17
4
93
806
64
675
85
4
30
088
n i
68
'* 7
J778
70.2
2534
24
Sep 18
18 >S
62
131
304
6
2712
92
296
14
33
14
119
855
215
562
8
13
169
45
1307
58
31H
5 j
•-•03)
36.0
5650
24
Sep 17
18>8
108
49
517
3
5253
167
34
221
27
38
11
27
699
186
569
10
70
128
6131
75. :>
.'48
3.1
1738
21.4
8117
24
Sep 17
8->-S
191
60
180
7
1956
131
166
11
110
1171
53
488
21
233
32
2525
32. S
166
3.5
2119
44.1
4810
25
Sep 18
2^S
54
73
218
4853
174
3
522
13
25
3
130
623
196
547
3
41
158
54
5375
69.9
535
7.0
1780
23.1
7690
26
Sep 18
33^17
13
35
25
4038
15
164
16
115
22
4
2
31
138
107
82
16
51
11
4306
88.1
137
7.8
442
9.0
4885
26
Sep 18
17 *S
147
12
96
8613
189
581
21
6"!
60
231
1099
389
407
63
201
174
9057
73-4
602
4.9
2687
21.8
12346
27
Sep 18
5CH-15
4
3
27
12
3279
28
149
24
144
4
7
62
322
83
150
33
29
10
3526
80.;
148
3.4
696
15.9
4370
27
Sep 18
15->S
31
20
87
17
6286
117
7
615
37
27
49
219
1455
312
497
107
229
95
656S
64 . H
652
6.4
2985
29. J
10202
28
Sep 18
61 -S
9
29
36
1
3322
25
49
1
211
i
1.
10
55
204
1?6
120
1
49
46
1
14
347?
80. i
2)3
4.9
6 \~>
I4./
4322
-------
App. F.2 cont.
Cruise: 2
oo
Station:
Date:
Tow length
In meters:
Species:
Calanoid Copepoda
D ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopod Copepoda
C bi th
M edax
T pr mex
Cladocera
L kind
P peel
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lame 11
Clad imn.
Calan Tot (#/m:')
Calan Tot (%)
Cyclo Tot (#/m3)
Cyclo Tot (%)
Clad Tot (#/m3)
Clad Tot (%)
Grand Total
29
Sep 18
/O»20
3
2
3
17
3307
2
131
10
57
3
9
17
19
8
20
12
1
3475
96.0
60
1.7
86
2.4
3621
29
Sep 18
2O*S
9
4
99
9
4646
39
57
8
764
8
9
13
197
803
279
302
113
69
22
4871
63.4
772
10.4
1807
24.3
7450
JO
Sep 17
44>13
27
2
15
29
8728
14
61
4
222
2
5
42
83
61
36
1
29
7
5
8880
94.7
224
2.4
269
2.9
9373
30
Sep 17
13->S
106
4
137
20
7534
27
35
584
12
8
4
353
893
615
278
204
74
51
7863
71.9
584
5.3
2492
22.8
10939
11
St-p 18
25-S
4
4
116
11
3779
22
851
17
1 7
4
177
15V
435
989
225
50
74
<936
47.2
868
10.4
3528
42.3
8332
)«
riep 1 /
21 -S
41
98
98
3191
112
7
324
11
15
15
50
648
123
818
14
236
0 1
ISA/
60.5
335
5.7
1982
33.8
5864
19
Sep 17
43-»S
28
60
92
5103
101
32
224
11
14
14
267
515
89
261
8
234
7j
-.416
"6.0
235
3.3
1475
20.7
7126
40
Sep 17
11+S
73
252
75
2129
488
132
L7
">/
9
9
531
1353
64
469
92
323
/8
3017
49.0
149
2.4
2985
48.5
6151
41
Sep i;
53 '15
5
5
15
20
1917
25
193
14
52
15
1
7
105
7
17
3
20
i
2194
90.5
67
2.8
163
6.7
2424
41
Sep 1 7
15»s
22J
204
289
51
3599
119
509
10?
51
17
526
3480
68
458
17
306
68
4483
44.5
611
6.1
4991
49.5
10085
42
Sep 17
7S./5
1
1
2
12
622
1
157
8
41
3
2
2
46
9
5
11
11
2
804
85.9
44
4.7
88
9.4
936
42
Sep 17
2S-S
132
112
214
10
5132
204
10
856
20
61
10
20
224
2282
122
153
92
214
51
5814
58.6
876
8.8
3229
32.6
9919
43
Sep 17
83-20
1
2
13
9
2151
7
70
5
101
1
1 /
5
41
217
25
32
13
21
17
-'258
82.2
102
3.7
388
14.1
2748
43
Sep 1 /
:o-s
1 1 ^
2')
140
1 3
9983
51
51
M'>
13
1H
38
407
3069
216
280
153
140
204
I037H
66.6
658
4.2
4545
29.2
15581
-------
App. F.2 cont.
Cru1SP• J
Station: 4o
Date: Sep 17
Tow length
in meters: 122-20
Species:
Calanoid Copepoda
D ash 1
D min
D oreg
D siclis 8
T) cops 1053
E lac 1
L mac 119
S cal 12
Cyclopoid Copepoda
C bi th 12
M edax 1
T pr mex
Cladocera
L kind
P ped
D leuch
S cryst
H gtb 1
!) g^l me 1
D long 2
n retro ?
C lac
C quad
Cer rei
B long 3
F. roreg 2
D dent
A harp
A affin
A quad
C sphaer
E lamell
Clad imm.
Calan Tot (*/V) 1194
Calan Tot (%) 97
Cyclo Tot (ff/tn'1 13
Cyclo Tot (7) 1 .
Clad Tot H//ro') 1 •
i:lad Tot (/.) i.
Grand lotat '-'22
•4*4
Sep 17
20-S
42
95
lj
38
8242
45
62
469
13
13
15
250
1441
93
•14
85
23
89
8539
7 75 9
48/
.1 4. <
222'i
. t 19 <<
ll.>44
45
Sep 17
84-25
2
6
16
1315
I
159
4
50
6
1
1
12
22
17
13
13
5
1
2
1503
9L.3
5b
J.4
H1
j. i
164h
45
Sep I/
25-S
73
17
166
17
6478
36
5
620
12
12
27
2bl
1723
200
462
536
63
68
6792
63.0
632
5.9
•152
11. J
11)776
46
Sep 17
34>13
49
5
283
38
8423
29
4:3
343
19
3
11
22
547
136
509
82
11
35
8872
81 P
)bx
3.4
1 Cih
12 -
10S9<.
46
Sep 17
13->S
28
7
65
2511
30
11
460
4
51
86
758
217
759
J64
45
14
?652
49."
464
J* h
j;;q-
'2.4
•«.!
47
Sep 17
26-12
22
9
124
32
10924
24
5
223
12
13
3
347
313
181
65
3
35
11140
90 1
235
1 . v
Qfcn
.P
| ' | is
4/
Sep 17
12 -S
21
/
H
1914
149
11
357
4
1 1
35
2->
294
110
272
683
25
18
2111
'"•I. ')
361
9. 1
14.' '
i • '
39«,
4h
Sep 17
20->10
45
6
166
34
7920
130
3
170
H
7
699
246
337
3
4
31
)
39
8104
84.1
I 70
1 . '
\ '• 1
14 .0
W>\
48
Sep 17
10->S
13
53
3
4258
125
171
3
5
18
<•< '36
9,"
423
229
23
5
23
4452
'5.4
174
2.9
1? '9
_' |
590".
49
Sep 17
59-25
1
7
16
2664
132
8
40
4
3
178
4
11
17
4
19
2828
9J .0
6',
| £J
14541
50
Sep 17
32-10
24
55
17
10544
3
43
446
3
16
4
197
481
119
17J
86
.?3
4
103
10684
86 h
4^9
3.6
1 704
9. •<
1 'It/
50
Sep 17
10>S
71
173
2U
4329
?0
10
1039
10
.'(i
20
295
2017
'/S
91 '
1/b
10
462»
4H.4
lO/i 9
1 1 .(i
IKpn
't): t>
')')•
-------
Appendix F.3
Cruise: 3
Station :
Date:
Tow length
in meters:
Species:
Calanoitl Copopml.i
D ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Cladocera
L kind
P ped
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lamell
Clad imm.
Calan Tot (#/m3)
Calan Tot (%)
Cyclo Tot (#/mJ)
Cyclo Tot (%)
Clad Tot (#/m')
Clad Tot (%)
Grand Total
1
Oct 6
15--S
444
235
J66
13
9272
457
1854
104
91
39
392
2847
26
2089
692
131
26
379
10787
55.4
1958
10.1
6712
34.5
19457
2
Oct 6
23-+S
97
29
73
24
3124
354
500
19
34
15
160
1106
5
490
68
267
5
330
3701
5'>. 2
519
7.7
2480
37.0
6700
3
Oct 6
38^15
26
17
28
1
2008
100
181
12
8
h
36
216
6
163
19
79
1
47
2180
73.8
193
6.5
581
19.7
2954
3
Oct 6
15-+S
88
78
204
5826
689
940
17
48
27
136
2200
7
1508
71
407
14
17
336
6885
54.6
957
7.6
4771
37.8
12613
4
Oct 6
25->S
16S
146
142
18
4698
120
744
13
337
2458
4
607
44
248
208
5292
53.2
744
7.5
3919
39.4
9955
5
Oct 6
16 >S
7'-)
36
46
20
3142
142
496
30
13
10
116
1042
443
36
136
53
3465
59. <
526
9.0
1849
18.6
5840
6
Oct 6
12+S
'2
7
41
1962
26
1493
21
14
15
63
651
n
>47
95
186
107
2058
)8.6
1514
28.4
1750
33.0
5322
7
On 6
12>S
10
20
41
20
5724
153
20
1569
20
448
2047
61
346
1721
285
479
5988
49.1
1569
15.5
2571
25.4
10128
8
Of ( 6
23 >S
h
4693
55
1686
6
30
109
1728
18
164
176
273
73
4754
52.;
1692
18.8
2571
28.5
9017
9
Od h
41>S
104
26
287
5173
131
1254
2089
6216
78
H62
575
366
496
5719
32.4
1254
7.1
10682
60.5
17655
10
Or 1 h
23*14
25
1 1
40
15
4667
40
29
357
113
327
113
62
44
55
15
4827
81.6
357
6.0
729
12.3
5913
10
<)( t 6
14 >S
2J1
47
1 SJ
152
10702
156
7
1833
18
15
1855
8345
189
557
211
422
819
11406
44.4
1851
7.2
12413
48.4
25670
1 1
Oct t>
iJI >S
88
53
53
70
6375
73
896
Irt
53
1633
4373
105
246
351
263
316
6712
44.8
896
6.0
7358
49.2
14966
1 '
MI i (,
14 -S
170
191
64
846/
170
95S
21
1\
231 J
4987
424
2J3
21
509
297
1231
9062
45
955
4
10057
50
20074
-------
App. F.3 cont.
'•ruise: >
Station:
Date:
Tow length
in meters:
Species:
Calanoid Copepoda
1) ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Cladocera
i, kind
P ped
D leuc.h
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lamol 1
Clad 1mm.
Calan Tot (ff/m')
Calan Tot (%)
Cyclo Tot (it /at'')
Cycle Tot (%)
Clad Tot (#/niM
Clad Tot (%)
Grand Total
13
Oct 8
22->S
204
166
178
5157
509
1502
38
13
25
993
4100
38
980
153
815
586
6214
40.
1540
10.
7?03
49.
15457
1.4
Oct 8
24*S
35
100
93
54
3715
305
583
46
1 <>
8
606
1848
27
278
46
46''
390
4302
, 2 50 .
629
.0 7.
JbKl
,« 42.
861 '.'
15
Oct 8
25>S
50
66
28
39
3997
149
6
576
11
6
11
161
1268
454
72
637
316
4335
.0 55.2
587
3 7.5
2925
. v (7 . t
7847
16
Oct 8
i7>S
92
75
59
70
6227
324
779
32
14
20
284
1429
63
837
68
J62
390
6847
61.5
811
7.3
3467
31.2
11125
17
Oct 8
14-8
46
24
81
18
2527
209
2
142
7
4
i
156
532
14
137
68
163
58
2907
69.4
149
3.b
11 (4
n \
4J"0
ib
Oct 8
!5->S
131
176
52
52
5158
340
803
20
33
307
2638
26
516
104
620
24*
5909
52.6
823
7.3
4492
40.0
1 1 n-'t
19
Oct 8
24 >S
21
63
99
52
3423
94
496
37
21
21
271
1085
16
230
125
287
292
3752
58.4
533
8.3
2141
33.3
b42f>
20
Oct 8
I 7->S
68
91
68
79
8451
136
849
11
23
68
1720
2422
136
181
306
487
160
8893
58.3
860
5.6
5503
36.1
L5256
?1
Oct 8
13+S
93
46
139
69
7209
46
1313
46
995
5024
278
995
324
278
162
7602
44.7
1313
7.7
81(12
47. b
17017
22
Oct 8
20*S
57
66
12.5
172
9682
7
1294
42
7
59
974
2568
113
262
184
865
309
10109
60.2
]33ft
8.0
5 '341
31 .8
16786
23
Oct 8
17'K
59
34
140
64
8153
306
4
938
2S
25
2J
$61
896
136
488
119
301
144
876U
71.7
963
7.9
2491
20.4
12J14
24
Oct 7
17-S
25
25
45
14
2795
182
595
Jl>
y
}
6
73
446
45
219
126
140
3
51
3086
64.1
615
12.8
1115
23.2
4816
?4
O( t 8
1"? -S
10
13
159
73
7169
109
932
30
H
8
394
925
111
361
136
371
45
7533
69.4
962
8.9
2359
21.7
10854
2'j
Oct 8
25-»S
66
133
421
133
9632
576
22
2081
22
66
2059
8171
244
.1.528
266
509
288
109H)
41.9
20M1
7.9
1 H 5 '<
'>(). /
2M\ 1
-------
App. F.3 cont.
Cruise: 3
NJ
Station:
Date:
Tow length
tn meters:
Species:
Calanoid Copepoda
D ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopod Copepoda
C bi th
M edax
T pr mex
Cladocera
t kind
P ped
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
A quad
C sphaer
E lame 11
Clad imm.
Calan Tot (#/m3)
Calan Tot (%)
Cyclo Tot (#/m3)
Cyclo Tot (%)
Clad Tot (#/m3)
Clad Tot (%)
Grand Total
26
Oct 8
33->S
33
82
246
66
12387
49
2530
99
164
854
3779
1068
789
378
756
411
12863
54.3
2629
11.1
8199
34.6
23691
27
Oct 8
49>33
5
78
112
5968
5
332
39
509
15
--,
107
87
5
15
61
24
7
6539
88.7
524
7.1
311
4.2
7374
27
Oct 8
33->S
39
177
170
12608
31
1968
15
39
486
1999
147
224
231
556
170
13025
69.1
1968
10.4
3867
20.5
18860
28
Oct 8
63->44
11
41
112
3666
3
384
37
233
10
4
7
72
172
3
16
27
23
20
4254
87.9
243
5.0
344
7.1
4841
28
Oct 8
44 »S
58
46
58
116
7060
382
1030
23
625
2558
35
231
278
208
162
7720
60.0
1030
8.0
4120
32.0
12870
29
Oct 8
71>40
4
18
65
2456
2
160
10
196
4
1
4
29
27
2
1
6
10
1
2715
90.6
200
6. /
81
2. '
2996
29
Oct 8
40+S
19
19
153
57
8206
25
6
1127
19
6
64
236
1986
64
376
191
363
32
8485
65.5
1146
8.9
ms
25.6
12949
30
Oct 7
41 *30
10
10
1384
23
57
5
3
26
5
21
3
1427
92.2
57
3.7
63
4.1
1547
30
Oct 7
30->S
8
59
68
34
6221
59
1282
17
M
68
42
696
1961
42
297
416
272
263
6449
54. h
1299
11.0
4065
34.4
L1813
30
Oct 8
40->2h
17
29
25
4477
15
2
341
4
31
44
114
10
42
75
42
25
4565
86.2
341
6.4
387
7.3
5293
30
Oot 8
26> S
98
59
235
118
11008
118
1743
59
20
98
627
3761
78
627
392
1097
39
11636
57.7
1802
8.9
6739
33.4
20177
31
Oct 8
25.=;
44
44
177
89
7396
66
1506
44
66
13)
2901
7883
199
1395
531
841
664
7816
32.6
1550
6.5
14613
60.9
23979
32
Oct 6
19 -S
/")
45
60
8434
30
1932
45
IS
90
1393
7879
240
1348
240
360
584
8644
38.0
1977
8.7
12149
53.4
22770
3:)
Or t 6
Ik >K
46
46
116
116
9213
35
1377
162
683
2616
93
208
289
313
185
9572
61.8
1377
8.9
4549
29.4
15498
-------
App. F.3 con t.
Cruise: 3
u>
Station:
Date:
Tow length
in meters:
Species:
Calanoid Copepoda
D ash
D min
D oreg
S siclis
D cops
E lac
I, mar
S ral
Cyclopoid Copepoda
C bi th
M edax
T pr mex
Cladocera
L kind
P ped
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affln
A quad
C sphaer
E lamell
Clad iiran.
Calan Tot (#/m3)
Calan Tot (%)
Cyclo Tot (#/m3)
Cyclo Tot (%)
Clad Tot (#/m')
Clad Tot (%)
Grand Total
34
Oct 6
38*25
2
J6
13
2077
6
2
189
2
4
2
46
40
8
2
11
2136
87.5
191
7.8
113
4.6
2440
34
Oct h
25*S
92
20
102
102
H865
31
2078
194
591
3392
9?
285
173
479
418
13212
63.
2078
9.
5624
26.
20914
35
Oct 6
48*38
I
32
897
6
214
90
9
17
35
6
3
9
1152
.2 87 . 2
99
,9 7.5
70
.9 5.3
1321
35
Oct 6
38*S
47
7
47
34
6976
74
IO"/40
3
279
253
6
12
J
4
I
1
541
96.3
12
> .]
9
1.6
562
-------
App . F.3 cont.
Cruise: 3
Station:
Date:
Tow length
in meters;
Species:
Caianoid Copepods
D ash
D min
D oreg
D siclis
D cops
E lac
L mac
S cal
Cyclopoid Copepoda
C bi th
M edax
T pr mex
<;ladcc.era
I, kind
P pcd
D leuch
S cryst
H gib
D gal me
D long
D retro
C lac
C quad
Cer ret
B long
E coreg
D dent
A harp
A affin
\ quad
'' sphaei
E lame 11
Clad imm.
Calan Tot (#/nr)
Calan Tot (%)
Cyclo Tot (#/m3)
Cyclo Tot (%)
Clad Tot (#/m3)
Clad Tot (%)
Grand Total
42
Oct 7
40-S
6
13
41
19
2820
67
245
10
236
694
16
67
38
131
159
2966
65.0
245
5.4
1351
29.6
4562
43
Oct 7
81 • 15
11
141
257
20
12
1
1
13
2
1
3
1
429
92.7
1 i
2.8
21
4.5
463
43
Oct /
35-S
7
22
87
65
7770
58
822
16
22
742
2168
7
29
160
226
175
8009
64. 6
822
0.7
3565
28.8
12396
44
Oct 7
120-50
6
89
129
11
6
1
5
3
1
235
93.6
7
2.8
9
3.6
251
,,
Oct 7
50-b
20
61
41
4828
20
611
31
306
1813
10
163
71
173
51
4970
60 6
611
7.5
2618
31.9
8199
45
Ocl .'
85>LS
1
1
6
22
1487
2
16
1
154
8
2
1
10
54
7
8
11
10
1
1536
85 _'
162
9.0
104
5.8
1802
4'>
Oct 7
15-S
42
127
102
136
5467
34
1664
17
34
679
4015
119
382
212
323
289
5908
4 >.. i
Lbbt
12.2
6070
44.5
1J642
46
Ocr 7
34-18
10
63
78
5738
2
5
413
12
2
12
218
21
17
61
17
26
5896
88.1
425
6.3
374
5.6
6695
46
Oct 7
18-S
7
28
134
5
7894
71
1344
7
1.4
7
113
325
1938
57
297
531
467
226
8139
60.4
1351
10.0
3975
29.5
13465
47
Oct 7
25-S
19
123
78
6873
13
4
590
15
46
194
454
45
172
340
95
51
7110
78.0
605
6.6
1397
15.3
9112
48
Oct 7
20-S
6
1
72
42
3379
5
1
490
5
12
3
37
44
224
14
120
228
28
28
3506
74.0
495
10.4
738
15.6
4739
49
v |