United States
Environmental Protection
Agency
Region 5,
Great Lakes National EPA-905/3-88-001
Program Office GLNPO Report No. 3
230 South Dearborn Street February 1988
Chicago, Illinois 60604
Phytoplankton and
Zooplankton in Lakes
Erie, Huron, and
Michigan: 1984
Do not WEED. This document
should be retained in the EPA
Region 5 Library Collection.
-------
EPA-905/3-88-001
GLNPO Report Mb.3
February 1988
Phytoplankton and Zooplankton
In Lakes Erne, Lake Huron and Lake Michigan: 1984
Volume 1 - Interpretive Report
by
Joseph C. Makarewicz
Department of Biological Sciences
State University of New York at Brockport
Brockport, New York 14420
March 1987
Project Officer
Paul Bertram
U.S. Environmental Protection Agency
Great Lakes National Program Office
230 South Dearborn Street
Chicago, Illinois 60604
U.S. Environmental Protection Afencf
Region 5, library (PI-12J)
77 West Jackson Boulevard, 12th Floor
Chicago, II 60604-3590
-------
Abstract
With the acknowledgement that biological monitoring was fundamental
to charting ecosystem health (Great Lakes Water Quality Agreement 1978),
EPA's program was developed for Lakes Erie, Huron and Michigan to: 1)
monitor seasonal patterns, ranges of abundance and, in general, structure
of the phytoplankton and zooptankton communities; 2) relate the biological
components to variations in the physical, nutrient and biological
environment; and 3) assess the annual variance to allow better long-term
assessments of trophic structure and state. Several offshore stations
(9-11) on several cruises (9-11) during the spring, summer and autumn of
1984 and winter of 1985 were sampled.
By examining changes in the phytoplankton and zooplankton in relation
to water chemistry, evidence was found suggesting little change in the
trophic status of Lakes Huron and Michigan while an improvement in the
trophic status of Lake Erie was evident. The offshore region of Lake
Michigan is experiencing changes in phytoplankton and zooplankton
composition consistent with nutrient control and top-down control by fish.
Even so, the biomass of phytoplankton and zooplankton and the trophic
status of the lake have not changed significantly. The appearance and
establishment of Daphnia pul icari a in offshore waters of Lake Huron
suggest a change in the forage fish base. With the exception of the
resurgence of Asterjonella formosa in Lake Erie, plankton composition has
changed little since the 60's. However, dramatic reductions in biomass of
nuisance and eutrophic indicator species have occurred. These changes are
consistent with expectations of long-term nutrient control. However, a
change in piscivory is evident that has apparently allowed the
establishment of the large cladoceran Daphnia pulicaria.
tfi **tp.j,T.lt>;fyi3 .£.0
• f''» v^tfU,;* »VS#K<
vo?' !»<:.':*,:.* ft>jW Tt
-l-^a^ jl s.
-------
DISCLAIMER
This report has been reviewed by the Great Lakes National Program Office,
U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views
and policies of the U.S. Environmental Protection Agency, nor does mention
of trade names or commercial products constitute endorsement or
recommendation for use.
-------
IV
FOREWARD
The Great Lakes National Program Office (GLNPO) of the United States
Environmental Protection Agency was established in Region V, Chicago, to
focus attention on the significant and complex natural resource
represented by the Great Lakes.
GLNPO implements a multi-media environmental management program drawing on
a wide range of expertise represented by universities, private firms,
State, Federal and Canadian Governmental Agencies and the International
Joint Commission. The goal of the GLNPO program is to develop programs,
practices and technology necessary for a better understanding of the Great
Lakes ecosystem and to eliminate or reduce to the maximum extent
practicable the discharge of pollutants into the Great Lakes system. The
Office also coordinates U.S. actions in fulfillment of the Great Lakes
Water Quality Agreement of 1978 between Canada and the United States of
America.
This report presents results of the phytoplankton and zooplankton portions
of the water quality surveillance program conducted by GLNPO on Lakes
Michigan, Huron and Erie in 1984 and in winter of 1985. Results of the
physical and chemical portions of the surveillance program may be found in
a companion report:
Lesht, Barry M. and David C. Rockwell. 1987. The State
of the Middle Great Lakes: Results of the 1984 Water
pual ity Survey of Lakes Erie, Huron and Michigan.
Publication Number ANL/ER-87-1. Argonne National
Laboratory, Argonne, Illinois 60439.
GLNPO grateful Iy acknowledges the contribution to this study of the
Bionetics Corporation, with whom GLNPO contracted for assistance in the
collection of samples and for the identification and enumeration of the
phytoplankton and zooplankton. In particular, we extend appreciation to
Norman A. Andresen, Mark A. Lamb, Louis L. Lipsey, Donna Page and Heather
K. TrulI I.
Funds for this report were provided by U.S.E.P.A., Great Lakes National
Program Office under Grant Number R005772-01.
-------
TABLE OF CONTENTS
Ease.
Abstract I i
Disclaimer .. i i i
Foreward iv
Tab! e of Contents v
L i st of Tab! es. " v i i I
L ist of Figures .xi i
Acknow I edgments xv i I
OVERV IEW 1
SUMMARY
Lake Mich igan 1
Lake Huron 5
Lake Erie 8
INTRODUCTION 11
METHODS
Samp I ing Si tes 14
Chem i stry 14
Phytop I ankton ..14
Zoop I ankton. 16
Data Organization. 17
RESULTS AND DISCUSSION - LAKE MICHIGAN
Phytop I ankton 19
Annual Abundance of Major Algal Groups ....19
Seasonal Abundance and Distribution of Major Algal Groups..19
Regional and Seasonal Trends In the Abundance of
Common Taxa 21
Vert ica I D i str i but ion 27
W i nter Cru i se 28
Historical Changes in Species Composition 29
P i cop I ankton 33
Geographical Abundance and Distribution ..33
Indicator Species... 36
Historical Changes in Community Abundance 37
Zoop I ankton 39
Annual Abundance of Zoopl ankton Groups ..39
Seasonal Abundance and Distribution of Major
Zoop I ankton Groups 39
Geographical Abundance and Distribution of
Zoopl ankton Groups 40
Common Species. .40
Changes in Species Composition 41
Crustacea 41
Rot i f er a 45
Historical Changes in Zoop I ankton Biomass 46
Indicators of Trophic Status ..46
-------
VI
Page
Troph ic Interactions 49
RESULTS AND DISCUSSION - LAKE HURON
Phytop I ankton 52
Annual Abundance of Major Algal Groups 52
Seasonal Abundance and Distribution of Major
Algal Groups 52
Geographical Abundance and Distribution of Major
AI gal Groups 53
Regional and Seasonal Trends in the Abundance of
Common Taxa 54
Vertical Distribution ...,58
W i nter Cru i ses 59
Historical Changes in Species Composition 60
P i cop I ankton 61
Indicator Species 61
Historical Changes in Community Abundance and Biomass 63
Zoopl ankton 65
Annual Abundance of Zoop I ankton Groups 65
Seasonal Abundance and Distribution of Major
Zoop I ankton Groups 65
Common Species 66
Changes in Species Composition 66
Crustacea 66
Rot i f era 69
Geographical Abundance and Distribution of
Zoop I ankton Groups 70
I nd i cators of Troph i c Status 71
Historical Trends in Abundance 73
Troph ic I nteract ions 74
RESULTS AND DISCUSSION - LAKE ERIE
Phytopl ankton 76
Annual Abundance of Major Algal Groups 76
Seasonal Abundance and Distribution of Major
AI gal Groups 77
Geographical Abundance on Distribution Major
of Major Algal Groups.. 77
P i cop I ankton 78
Regional and Seasonal Trends in the Abundance
of Common Spec i es 79
Changes in Species Composition 82
Indicator Species 84
Historical Changes in Community Biomass 85
Zoopl ankton. 87
Annual Abundance of Zoopl ankton Groups 87
Seasonal Abundance and Distribution of Major
Zoopi ankton Groups 87
Geographical Abundance and Distribution of
-------
vn
Page
Zoop I ankton Groups .88
Common Species .89
Changes in Species Composition 89
Crustacea. 89
Rot i f era 92
East-West Species Distribution 93
Indicators of Trophic Status ..93
Historical Changes in Abundance ...95
Trophic Interactions 97
L ITERATURE CITED 102
TABLES 113
F IGURES 168
APPENDICES
Species List - Phytoplankton
Table A. Lake Michigan 238
Table B. Lake Huron 248
Table C. Lake Erie 257
Species List - ZoopIankton
Table D. Lake Michigan.. 267
Table E. Lake Huron 270
Table F. Lake Erie 273
VOLUME 2. DATA SUMMARY REPORT. Summary sheets of phytopiankton
and zoopI ankton data ATTACHED MICROFICHE
-------
vm
TABLE LEGENDS
Page
TABLE 1 Plankton sampling dates for Lakes Michigan,
Huron and Erie in 1984 and 1985 113
TABLE 2 Latitude and longitude of plankton sampling
stat ions, 1984 114
TABLE 3 Sample dates and stations for Lake Michigan,
1984 and 1985 116
TABLE 4 Sample dates and stations for Lake Huron,
1984 and 1985 117
TABLE 5 Comparison of calculated crustacean dry weights
to measured dry weights in Lake Michigan 118
TABLE 6 Mean values of physical-chemical parameters
(ApriI-October) from a 1-m depth for Lakes Erie,
Michigan and Huron, 1984 119
TABLE 7 Number of species and genera observed in each
algal division or grouping in Lake Michigan,
1983 and 1984 120
TABLE 8 Relative abundance of major phytoplankton
divisions in Lake Michigan, 1983 and 1984 121
TABLE 9 Abundance of Rh i zosoI en i a eriensis in Lake
Michigan in 1983 and 1984 122
TABLE 10 Summary of common phytoplankton species occurrence
in Lake Michigan, 1984 123
TABLE 11 Common species observed in either 1983 or 1984
but not both years, Lake Michigan 124
TABLE 12 Number of species in Lake Michigan with depth
at Station 47, 15 August 1986 125
TABLE 13 Comparison of abundance of Cyclotella species
at offshore sites in August of 1970, 1983 and
1984, Lake Michigan 126
TABLE 14 Comparison of nutrient levels between Stations
6, 64, 77 and all other stations during the
spring and fall, Lake Michigan 127
TABLE 15 Distribution of indicator diatom species in Lake
Michigan 128
TABLE 16 Relative abundance of zoopIankton In Lake Michigan..129
-------
IX
Page
TABLE 17 Summary of common zooplankton species occurrence
in Lake Michigan during 1984 130
TABLE 18 Cladoceran abundance in 1954, 1966, 1968, 1983
and 1984 in Lake Michigan 131
TABLE 19 Copepoda abundance in 1954, 1966, 1968, 1983
and 1984 in Lake Michigan..... 133
TABLE 20 Average crustacean zooplankton biomass for 1976
and 1984, Lake Michigan 135
TABLE 21 The ratio of calanoids to cyclopoids plus
cladocerans geographically in Lake Michigan,
1983 and 1984 136
TABLE 22 Correlation of phytoplankton with total phosphorus
concentrations and zooplankton abundance
within individual cruises in Lake Michigan 137
TABLE 23 Number of species and genera observed in each
algal division or grouping, Lake Huron, 1983
and 1984 138
TABLE 24 Relative abundance of major phytoplankton
divisions in Lake Huron, 1983 and 1984 139
TABLE 25 Abundance of Rhizosolenia eriensis in Lake
Huron, 1983 and 1984 140
TABLE 26 Summary of common phytoplankton species occurrence
in Lake Huron during 1984 and winter of 1985 141
TABLE 27 Common species observed in either 1983 or 1984
but not in both years, Lake Huron 142
TABLE 28 Distribution of indicator diatom species in
Lake Huron 143
TABLE 29 Relative abundance of zooplankton in Lake Huron 144
TABLE 30 Summary of common zooplankton species occurrence
in Lake Huron during 1984 145
TABLE 31 Comparison of mean crustacean abundance for the
sampling period in 1971 (Apr!I-November),
1974/75 (April-November), 1983 (August-October)
and 1984 (April-December), Lake Huron 146
TABLE 32 Abundance of selected zooplankton species in
northern and southern Lake Huron in 1984 147
TABLE 33 Ratio of Calanoida to Cladocera plus Cyclopoida
in Lake Huron, 1983 and 1984 148
-------
X
Page
TABLE 34 Comparison of the plankton ratio (Calanoida/
Cyclopoida+Cladocera) between the northern
stations of Lake Huron and Lake Michigan .149
TABLE 35 Mean abundance of rotifers in Lake Huron in
1974 and 1983 150
TABLE 36 Correlation of phytoplankton abundance with
total phosphorus concentrations and zoopIankton
abundance within individual cruises, Lake
Huron 151
TABLE 37 Number of species and genera observed in each
algal division or grouping, Lake Erie, 1983
and 1984 152
TABLE 38 Number of species identified and percentage of
species belonging to various taxonomic groups,
Lake Erie 153
TABLE 39 Annual phytoplankton biomass for the entire lake
and the western, central and eastern basins of
Lake Erie, 1983 and 1984 154
TABLE 40 Summary of common phytoplankton species occurrence
in Lake Erie, 1984 and winter of 1985 155
TABLE 41 Location of maximum abundance of selected species
in 1983 and 1984, Lake Erie 156
TABLE 42 Common species observed in either 1983 or 1984
but not both years, Lake Erie. 157
TABLE 43 Importance of Asterionel I a iooacisa during the
spring of 1984, Lake Erie 158
TABLE 44 Mean maximum biomass of selected common phyto-
plankton species in 1970 and 1983, Lake Erie 159
TABLE 45 Distribution of indicator diatom species in the
western basin of Lake Erie..... 160
TABLE 46 Trophic status of the western, central and eastern
basins of Lake Erie in 1970 and 1983/84 161
TABLE 47 Relative abundance of zooplankton in Lake Erie 162
TABLE 48 Summary of common zooplankton species occurrence
in Lake Erie during 1984 .163
TABLE 49 Occurrence of eutrophic zooplankton indicator
species in Lake Erie, 1984 164
-------
XI
Page
TABLE 50 Ratio of calanoids to cladocerans plus cyclopoids
in Lake Erie, 1983 and 1984 165
TABLE 51 Turbidity levels in 1978 and 1984, Lake Erie 166
Table 52 Correlation of phytoplankton abundance with total
phosphorus concentration and zoopIankton abundance
within individual cruises, Lake Erie 167
-------
xi i
FIGURE LEGENDS
Page
FIGURE 1. Lake Michigan plankton sampling stations, 1984-85 168
FIGURE 2. Lake Huron plankton sampling stations, 1984-85 169
FIGURE 3. Lake Erie plankton sampling stations, 1984-85 170
FIGURE 4. Seasonal phytoplankton abundance and biovolume
trends in Lake Michigan, 1984-85 171
FIGURE 5. Seasonal distribution of algal divisions in Lake
Michigan, 1984-85 172
FIGURE 6. Mean seasonal distribution of Cyclotella
ocelIataf Synedra ulna v. chaseana,
Synedra f iI iformis and Rhizosolenia
long! set a, Lake Michigan 173
FIGURE 7. Mean seasonal distribution of Nitzsch ia
Iauenburgiana, Qpcystis submarina,
Dictyosphaerium ehrenbergianum and
Cryptomonas rostratiformisf Lake Michigan 174
FIGURE 8. Mean seasonal distribution of Qsc iI Iator i a
minimaf Lake Michigan 175
FIGURE 9. Seasonal and geographical distribution of
Cyclotella pee I|ata, Oocystis submarina,
Dictyosphaerium ehrenberg ianum and
Osci I I ator i a min ima, Lake Mi ch igan 176
FIGURE 10. Vertical distribution of phytoplankton at Station
47, 15 August 1984, Lake Michigan 177
FIGURE 11. Vertical distribution of phytoplankton at Station
18, 15 August 1984, Lake Michigan 178
FIGURE 12. Annual geographical distribution of major algal
divisions in Lake Mich igan, 1984-85 179
FIGURE 13. Geographical distribution of phytoplankton abundance
on all cruises, Lake Mich igan, 1984-85 180
FIGURE 14. Historical abundance of phytoplankton in Lake
Michigan 181
FIGURE 15. Seasonal zooplankton abundance in Lake Michigan,
1984 182
FIGURE 16. Seasonal fluctuation (numerical) of zooplankton
groups in Lake Michigan, 1984....... 183
-------
xm
Page
FIGURE 17. Seasonal fluctuation (biomass) of zooplankton
groups in Lake Michigan, 1984 184
FIGURE 18. Geographical distribution (numerical) of major
zooplankton groups in Lake Michigan, 1984 ..185
FIGURE 19. Geographical distribution (biomass) of major
zooplankton groups in Lake Michigan, 1984 186
FIGURE 20. Geographical distribution of Diaptomus sici1 is
in Lake Michigan, 1984 187
FIGURE 21. Geographical distribution of selected zooplankton
in Lake Michigan, 1984 188
FIGURE 22. Geographical distributin of selected zooplankton
in Lake Michigan, 1984 189
FIGURE 23. Historical trends in zooplankton biomass during July
and August, Lake Mich igan 190
FIGURE 24. Seasonal phytoplankton abundance and biovolume
trends in Lake Huron, 1984-1985 191
FIGURE 25. Seasonal distribution of algal (% biovolume)
divisions in Lake Huron, 1984-85 192
FIGURE 26. Annual geographical distribution of major algal
division in Lake Huron, 1983 193
FIGURE 27. Annual geographical distribution of major algal
divisions in Lake Huron, 1984-85 194
FIGURE 28. Geographical distribution of phytoplankton
abundance on all cruises, Lake Huron, 1984-85 195
FIGURE 29. Mean seasonal distribution of Cyclotella
stelI igeraf Stephanod iscus alp inus,
Stephanod iscus minutus and Cosmarium sp., Lake
Huron 196
FIGURE 30. Mean seasonal distribution of Osc 1.1.1 atari a
minima. Lake Huron 197
FIGURE 31. Vertical distribution of phytoplankton at
Station 37, 15 August 1984, Lake Huron 198
FIGURE 32. Vertical distribution of phytoplankton at
Station 15, 15 August 1984, Lake Huron 199
FIGURE 33. Historical offshore biomass trends in Lake Huron 200
-------
x;v
Page
FIGURE 34. Seasonal zooplankton biomass and abundance
in Lake Huron, 1984 201
FIGURE 35. Seasonal fluctuation (numerical) of zooplankton
groups in Lake Huron, 1984 202
FIGURE 36. Seasonal fluctuation (biomass) of zooplankton
groups in Lake Huron, 1984 203
FIGURE 37. Geographical distribution of Daphnl.a pul icaria
in 1983 and 1984, Lake Huron 204
FIGURE 38. Geographical distribution (numerical) of major
zooplankton groups in Lake Huron, 1984 205
FIGURE 39. Geographical distribution (biomass) of major
zooplankton groups in Lake Huron, 1984 206
FIGURE 40. Geographical distribution of major zooplankton
groups in Lake Huron, 1983 207
FIGURE 41. Geographical distribution of selected Rotifera
and Copepoda in Lake Huron, 1984 208
FIGURE 42. Water chemistry along the north-south axis of
Lake Huron, 1984 209
FIGURE 43. Crustacean abundance of Lake Huron, 1970-1984 210
FIGURE 44. Abundance of Rotifera in Lake Huron in 1974,
1983 and 1984 211
FIGURE 45. Seasonal phytoplankton abundance and biovolume
trends in Lake Erie, 1984-85 212
FIGURE 46. Seasonal distribution of algal divisions in Lake
Erie, 1984-85 213
FIGURE 47. Annual geographical distribution of major algal
divisions in Lake Erie, 1984-85.. 214
FIGURE 48. Geographical distribution of phytoplankton
abundance on all cruises, Lake Erie, 1984-85 215
FIGURE 49. Geographical distribution of selected species,
Lake Erie, 1984-85 216
FIGURE 50. Geographical distribution of selected species,
Lake Erie, 1984-85 217
FIGURE 51. Mean seasonal distribution of Asterionella
formosa, Me Ios i ra isl andicaf Anabaena
sp. and Crucigenia rectangul aris, Lake Erie 218
-------
XV
Page
FIGURE 52. Seasonal fluctuation of weighted mean phytoplankton
biomass in 1970, 1983 and 1984, Lake Erie 219
FIGURE 53. Regression of phytoplankton biomass versus time
in western Lake Erie 220
FIGURE 54. Time trend in annual cruise mean concentration of
corrected chlorophyll _a since 1970, Lake Erie........221
FIGURE 55. Time trend in annual cruise average of total phosphorus
since 1970, Lake Erie 222
FIGURE 56. Seasonal zoopIankton abundance and biomass in
Lake Erie, 1984.. 223
FIGURE 57. Seasonal abundance distribution of zoopIankton
groups in Lake Erie, 1984 224
FIGURE 58. Seasonal biomass distribution of zoopIankton
groups in Lake Erie, 1984 225
FIGURE 59. Geographical distribution (numerical) of
zoop I ankton groups in Lake Erie, 1984 226
FIGURE 60. Geographical distribution (biomass) of
zoopl ankton groups, 1984, Lake Erie... 227
FIGURE 61. Geographical distribution of selected Crustacea
in Lake Erie, 1984 228
FIGURE 62. Geographical distribution of selected Rotifera
in Lake Erie, 1984 229
FIGURE 63. Crustacean zoopIankton abundance since 1939 in
the western basin of Lake Erie 230
FIGURE 64. July and August abundance of Cladocera and
Copepoda in the western basin of Lake Erie
s i nee 1939 231
FIGURE 65. Seasonal fluctuation of weighted mean Crustacea
(nauplii excluded) abundance in 1970, 1983, 1984,
Lake Erie 232
FIGURE 66. Seasonal fluctuation of Rotifera in the western
basin of Lake Erie from 1939 - 1983 233
FIGURE 67. Abundance of fishable walleye in western Lake Erie
(Ohio waters) 234
FIGURE 68. Sport angler harvest of walleye from the central
basin of Lake Erie 235
-------
XVI
Page
FIGURE 69. Time trend of emerald and spottail shiner abundance
in the central basin and alewife from the western
basin of Lake Erie 236
FIGURE 70. Seasonal and geographical turbidity trends in Lake
Erie 237
-------
xvn
ACKNOWLEDGEMEOTS
Ted Lewis provided the technical expertise on the INFO database and
other software. Diane Oleson inputed the raw data into the computer. P.
Bertram, D. Rockwell, G. Fahnenstiel and other anonymous reviewers
provided constructive comments that improved the manuscript. I thank them
for their time and effort.
-------
OVERVIEW
With the acknowledgement that biological monitoring was fundamental to
charting ecosystem health (Great Lakes Water Qua I Ity Agreement 1978),
EPA's program was developed for Lakes Erie, Huron and Michigan to: 1)
monitor seasonal patterns, ranges of abundance and structure of the
phytoplankton and zooplankton communities; 2) relate the biological
components to variations in the physical, nutrient and biological
environment; and 3) assess the annual variance to allow better long-term
assessments of trophic structure and state.
The program has proven successful. By examining changes in the
phytoplankton and zooplankton in relation to water chemistry, evidence was
found suggesting little change in the trophic status of Lakes Huron and
Michigan while an improvement in the trophic status of Lake Erie was
evident within the past ten years. The offshore region of Lake Michigan
is experiencing changes in phytoplankton and zooplankton composition
consistent with nutrient control and top-down control by fish. Even so,
the biomass of phytoplankton and zooplankton and the trophic status of the
lake have not changed significantly. The appearance and establishment of
Daphnia pulIcaria In offshore waters of Lake Huron suggest a change In the
forage fish base. With the exception of the resurgence of Asterlone I la
formosa in Lake Erie, plankton composition has changed little since the
60fs. However, dramatic reductions in biomass of nuisance and eutrophic
indicator species have occurred. These changes are consistent with
expectations of long-term nutrient control. However, a change in
piscivory is evident that has apparently allowed the establishment of the
large cladoceran Daphnia pulicaria.
The following summaries for Lakes Michigan, Huron and Erie outline the
major observations of the 1984 intensive sampling of the offshore region.
As such, the 1983 (Makarewicz 1987) and 1984 studies provide a basis for
long-term monitoring of the structure and functioning of the Great Lakes.
SUMMARY
Lake Michigan
1. In 1984, 327 algal and 52 zooplankton species were observed. Compared
to 1983, a 15? and 24% reduction in the number of algal and zooplankton
species were observed. As the same samp I ing, enumeration procedure and
taxonomists were employed, the observed flucuatlons In species composition
are due to both natural and sampling variability of the plankton
population.
2. Compared to Lake Huron, variability in common algal species in Lake
Michigan in 1983 and 1984 was high. 76? of the common species observed in
1984 were also common species In 1983. 31? of the common species observed
in 1983 were not common in 1984.
3. Average phytopIankton and zooplankton abundances were 22,220+1400
cells/mL and 59,764+8,284 organlsms/m for the study period. Mean algal
and zooplankton biomass were 0.55+.038 g/m and 33.2+4.9 mg/m for the
study period.
-------
4. As in Lakes Erfe and Huron, diatoms possessed the greatest diversity
of species (166) and biomass (70.0$ of the total) in 1984. The
Cryptophyta accounted for the second highest biomass in 1984.
5. Picopiankton represented 82.9$ of the total abundance but only 1.4$ of
the algal biomass.
6. Diatoms were dominant throughout the study period, accounting for as
much as 80$ but never less than 55$ of the phytopIankton biomass. The
overwhelming dominance of the diatoms in 1984 precluded the prominent
seasonal succession of aigal divisions observed in 1983.
7. The large drop in diatom bfomass observed in August of 1983 was not
observed in 1984, A bloom of Rhizosolenfa erlensis during 1984, not
observed In 1983, was the major cause of the dominance of diatoms in
August of 1984. A similar situation was observed in Lake Huron in 1984.
8. Abundance of phytopIankton decreased from the most northern station to
Station 57 and remained the same southward to the most southerly station,
where it increased slightly.
9. Vertical distribution studies indicated that an increase In abundance
occurred and a 100$+ Increase In species diversity occurred with depth at
Station 47. The Increase in abundance and diversity correlated with the
decrease In temperature associated with the metalImnion.
10. Winter samples were analyzed in 1985. Algal biomass and abundance
were low during the winter but were not significantly different from the
autumn and spring values. Diatoms and cryptophytes were predominant as
during the non-winter period. However, the relative importance of the
Cryptophyta increasd by a factor of >2 (11.6 to 25.3$).
11. The phytoplankton composition of Lake Michigan has changed. The
following subdominant or dominant species have decreased In abundance from
the 60's and 70's: Cyciotel I a m!ch iganlana, Cy dote I I a stel I igera,
MeIosIra is!apd ?caf Synedra acus and Ank ? strodesmus falcatus.
QscII Iatoria Iimnetlca has Increased In abundance. Abundance of
Rhizosolenfa eriensts increased in 1984 after a general decrease since the
60's and 70«s.
12. Dominant diatom species included the mesotrophic forms TabelI aria
flocculosa and Frag!I aria crotonensis and the oligotrophic forms
Cyciotella ocelI ata and Rhizosoienia erlensis. Compared to the 1983
cruises where mesotrophic forms were predominant, the same mesotrophic
forms were present in 1984 along with the oligotrophic Indicators.
13. The ratio of mesotrophic to eutrophic algal species (trophic ratio)
suggests a eutrophic status for nearshore waters In 1977, while the
offshore waters In 1970-71, 1983 and 1984 would be in the
oIigotrophlc-mesotrophic range.
14. Based on the classification scheme of Munawar and Munawar (19824,
Lake Michigan's algal biomass in 1983 (0.42 mg/m ) and 1984 (0.55 mg/m )
suggests an oligotrophic status for the offshore waters of Lake Michigan.
-------
15. Phytop Iankton abundance of the offshore waters appears to have
increased from 1962-63 to 1976-77 but has not significantly changed from
1976 to 1984. Because of the difference In enumeration methodology used
In the 1962-63 study compared with the other surveys, the suggested
increase in algal abundance from 1962-63 to 1976-77 has to be interpreted
cautiously,
16. The trend in zooplankton biomass was similar to the phytoplankton
trend between 1976 and 1984 in that no significant change in zooplankton
biomass was observed.
17. The Rotifera possessed the largest number of species (29) and
relative abundance (67.5$). The Rotifera contributed only 2.6% of the
biomass, while the Ciadocera accounted for 39.8$ of the zooplankton
biomass.
18. Abundance of zooplankton generally Increased from north to south.
The far northern stations (64 and 77) had a significantly higher abundance
than the rest of the lake. The northern Stations 64 and 77 and the
southern Stations 5 and 6 are best described as nearshore stations.
19. Both the 1983 and 1984 dominant rotifer composition was similar to
the nearshore and to Ahlstrom's (1936) offshore composition.
20. The species composition of the predominant rotifers suggests an
ollgotrophic offshore assemblage. Further support is provided by the high
relative abundance of Diaptomus ^icii Ls and L imnocalanus macrurus and the
occurrence of Senecella calanoides, all ol Igotrophic crustacean indicator
species.
21. The plankton ratio (Calanoida/Cladocera + Cyclopoida) was high
relative to Lake Erie but lower than Lake Huron. Except for the far
northern and southern extremes of the lake, the ratio was high and similar
indicating a similar high quality of water. At the far northern stations,
abundance of the olIgotrophic L imnocalanus macrurus and Diaptomus siciI is
was lower, while E"bosmina coregonI and Bosmlna Iong1rostrisf often
associated with eutrophic conditions, increased. In addition, four diatom
species Indicative of mesotrophic conditions were more abundant, and
phytoplankton abundance in general was higher at these northern stations
suggesting a lower water quality for the northern region. At Station 77,
si I lea and total phosphorus were higher than in the rest of the lake.
22. The changing nature of the zooplankton community of Lake Michigan was
evident in 1984. The abundance of Daphnia .-pul icaria, first observed in
1978, dropped from 376/m in 1983 to 78/m in 1984. Abundance of Q.
gal eata, rare In 1966 and 1968, was three times the density observed In
1954 (1200/m ). In general, the larger cladocerans, calanoids and
cyclopoid copepods, observed to have decreased In the early 60fs, had
Increased in abundance to values similar to those In August of 1954.
23. With a phytoplankton and zooplankton abundance and biomass between
those of Lakes Erie and Huron, the presence of the oligotrophic rotifer
associaton and the oltgotrophic crustacean indicator species Diaptomus
siciI Is and Limnoqalanus macrurusf the predominance of mesotrophic and
-------
ollgotrophic diatom species, and the similarity of the plankton ratio on
the north-south axis suggest that the offshore waters are currently In the
upper ol igotrophic-lower mesotrophic range (i.e. meso-oligotrophic).
24. A significant change in zooplankton composition has occurred with the
establishment of Daphnia pulIcaria in the entire offshore region of Lake
Michigan. Decline of the alewlfe population has apparently reduced
predatory pressure from alewife releasing the suppressed large-bodied
zooplankton such as Dqphnla pulIcaria (Scavla et al. 1986). In addition,
abundances of Leptodora k i ndt i i f Daphnia galeata, DIaptomus ash I and! and
Cyclops bicuspldatus have returned to or exceeded abundances observed in
1954 during a period of low alewlfe abundances.
25. Correlation analysis suggests that the Increases in Daphnia galeata
mendotaef as well as £. pul icarta, have exerted greater grazing pressures
on the phytoplankton community.
-------
SUMMARY
Lake Huron
1. In 1984, 315 algal and 53 zooplankton species were observed in Lake
Huron. Compared to 1983, a 4.3$ and 8.6% reduction In the number of algal
and zooplankton species occurred. These flucuations in species
composition are due to both natural and seasonal sampling variability.
2. Compared to Lake Erie, variability in common algal species in Lake
Huron between 1983 and 1984 was low. 94$ of the common species observed
in 1984 were also common species in 1983. 10% of the common algal species
observed in 1983 were not common in 1984.
3. Average biomass,of the phytoplankton and zooplankton was 0.38±.10 g/m
and 27.3+2.3 mg/m for the study period. Mean phytoplankton and
zoopIankton3 abundance were 17,200±890 cells/mL and 55,400+7,200
organisms/m .
4. Diatoms possessed the greatest number of species (156) and biomass
(61.9$ of the total) in 1984. The Chrysophyta were the second most
important division (9.5% of the total) in 1984, which represented a change
from 1983 when the Cryptophyta were second In Importance.
5. Picoplankton accounted for 83.9$ of the total abundance but only 1.4$
of the biomass. This finding is similar to that of 1983.
6. Considering biomass, the diatoms were dominant throughout the study
period accounting for as much as 12% but never less than 44? of the
biomass. The large drop in the relative importance of diatoms In August
of 1983 was not observed In 1984. A bloom of Rhizosolenia eriensis in
August of 1984, not observed in 1983, was the major cause of the dominance
of diatoms during the summer of 1984.
7. Average phytoplankton abundance for the sampling period generally
decreased from the northern stations to ~Station 15, where abundance
increased and then decreased si ightly southward. The mean station
zooplankton abundance was higher in the northern half than in the southern
half of the lake due primarily to higher rotifer abundance in the north.
8. In general, offshore species compositon of phytoplankton has changed
little since the early 70's. StephanodIscus minutus was not common in
1971, 1974, 1975, 1980 and 1983. In 1984 it was common with an average
density of 19.4 cells/mL because of the inclusion of winter samples.
Abundance averaged 63 cells/mL in February.
9. Vertical distribution studies Indicated that an increase in
picoplankton, BactIlariophyta and Chrysophyta occurred to a 30-m depth at
Station 37. The abundance increase correlates with the decrease In
temperature associated with the metalImnion.
10. Both in 1983 and 1984 the dominant diatom assemblages were species
characterized as indicators of oligotrophic or mesotrophic conditions.
-------
11. The ratio of mesotrophlc to eutrophic algal species (trophic ratio)
has not changed since 1971. This suggests that the trophic status of the
offshore waters of Lake Huron has not changed since 1971.
12. The Rotifera possessed the largest number of species (31) and
relative abundance (56.0%). The Calanolda (42.0$) dominated on a blomass
basis followed by the Cladocera (27.5$). Rotifera contributed only 2.5$
of the zooplankton biomass.
13. Species composition of zooplankton was similar In 1971, 1974, 1983
and 1984. Diaptomus oregonensis was more prevalent in 1983 and 1984,
while]), ash I and I and £. sic!I Is have Increased in abundance since 1971.
Limnocalanus macrurus appears to be decreasing In abundance. Bosmlna
IongIrostrIs and HQI oped I urn gibberum were more abundant in 1971 than 1984.
14. Daphnla pulI car I a was first observed In offshore waters In 1983. In
1984, lakewlde abundance decreased. Within the Cladocera, rank abundance
dropped from third In 1983 to fifth in 1984.
15. A new cladoceran species, Bythotrephes cederstromllf was observed in
the offshore waters of Lake Huron.
16. The rotifer community was dominated by an assemblage indicative of
oligotrophic conditions in 1983 and 1984. In addition, the calanold
PJaptoma.5 sjcjJig, an oligotrophic Indicator, was fairly abundant.
17. The plankton ratio (Calanoida/Cladocera + Cyclopoid) was high
compared to Lake Erie but similar for the entire offshore region, which
suggests a similar high quality of water over the entire offshore region
except for the far northern Station 61. The plankton ratio at Station 61
was similar to that of the Straits of Mackinac and northern Lake Michigan.
18. The presence of the oligotrophic rotifer assemblage, the domination
of the calanoids, the fairly abundant ollgotrophlc Diaptomus s?cllisf and
the low zooplankton abundance compared to those of Lakes Erie and
Michigan, suggest the offshore waters of Lake Huron In 1983 and 1984 were
ol igotroph ic.
19, Phytop Iankton biomass and zooplankton abundance of the offshore
waters of Lake Huron in 1971, 1980, 1983 and 1984 were not significantly
different. Similarly, offshore zooplankton biomass was not significantly
different between 1976 and 1984.
20. The consistency of the trophic ratio and algal biomass through time,
the Insignificant difference in zooplankton abundance from 1970-1984, the
occurrence of oligotrophic and mesotrophic algal indicator species, the
ollgotrophlc zooplankton assemblage, and the similarity of the plankton
ratio over the entire offshore suggest that no significant change in the
trophic status of the offshore waters of Lake Huron since 1970.
21. With a mean algal biomass of 0.38 and 0.42 g/m3 for 1984 and 1983,
respectively, Lake Huron would be classified as oligotrophic by the
classification scheme of Munawar and Munawar (1982).
-------
22. The appearance of Daphnla pul icaria In Lake Huron suggests that the
zooplankton community has been released from size-selective planktivory.
23. The correlation of phytoplankton abundance with total phosphorus and
zooplankton abundance within individual cruises suggests that "top down"
and "bottom up" control of the trophic web of lake ecosystems exists
simultaneously and that it varies with season.
-------
SUMMARY
Lake Erie
1. In 1984, 356 species of phytoplankton and 81 species of zooplankton
were observed. As compared to 1983, a 4.3$ reduction In phytoplankton
species, mostly Chlorophyta, and an 18.5? increase in zooplankton species,
mostly Rot Ifera, were observed. As the same sampling enumeration
procedure and taxonomy were employed, the observed flucuations In species
composition are due to both natural and sampling variability.
2. Compared to Lakes Michigan and Huron, a high variability In common
algal species existed between 1983 and 1984 in Lake Erie. Eighty-four
percent of the common species observed In 1984 were also common in 1983.
Thirty of the common species observed In 1983 were not common In 1984.
The number of common zooplankton species between 1983 and 1984 were
simiIar.
3. Mean phytoplankton and zooplankton abundance were 45,100±4,200
cells/mL and 159,600+25,300 organisms/m for the study period. Average
biomass of phytoplankton and zooplankton was 1.00+.16 and .053+.0062 g/m
in 1984. Phytop Iankton biomass varied within Lake Erie. The western
basin possessed, a greater biomass (1.38+0.23 ,g/m ) than the eastern
(0.54±0.082 g/m > and central (0.76±0.09 g/m ) basins. Zooplankton
abundance increased in a similar fashion Into the western basin but not
zooplankton biomass.
4. Diatoms possessed the greatest diversity of species (171) and biomass
(47.8$ of the total) in 1984. Compared to 1970, a significant change in
diversity of phytoplankton has occurred. In 1970 only 21 diatom species
were observed that accounted for 53$ of the biomass. The Chlorophyta
possessed the largest number of species (78) In 1970.
5. Picoplankton accounted for 89.6$ of the total abundance. A similar
finding was observed In 1983.
6. Diatoms were dominant in April and May and were succeeded by the
Cryptophyta in July and the Chlorophyta in August. By December and
through the winter months, the diatoms were again dominant.
7. The historically highly productive western basin has had a steady
decrease in algal biomass from 1958 to 1984. Similarly, chlorophyll .a
levels have decreased In all basins, but most dramatically In the western
basin. However, algal biomass is still higher In the western basin than
in the central and eastern basins.
8. Lakewide, the mean weighted alga! biomass was 3.4, 1.5 and 0.8 g/m In
1970, 1983 and 1984, respectively. A 56 to 76$ reduction in algal biomass
has occurred in offshore waters of the lake from 1970 to 1983/84.
9. Although occurrences of common and dominant species were similar in
1970, 1983 and 1984, dramatic decreases in the biomass of these species
were evident. For example, a 96$ reduction in the maximum biomass of the
nuisance species ftphanizomenon fIos-aquae has occurred since 1970. The
-------
eutrophlc Indicator species Stephanod\scus binderanus and Frag 11aria
capucina have had a >90.$ reduction In maximum blomass.
10. Aster toneI la formosa has not been prevalent in Lake Erie since prior
to 1950. In the 1984 spring cruises, .A., formosa was the dominant species
on a blomass basis. Meios!ra isiandjca, a mesotrophic indicator not
common in 1983, was common in 1984.
9. The Rotifera possessd the largest number of species (48) and relative
abundance (80.1$) of the zooplankton. On a biomass basis, the Rotifera
represented only 13.6$ of the zooplankton biomass while the Cladocera
contributed 40.5$ of the biomass.
10. A shift in zooplankton composition is occurring with a new species
Daphnia pulIcaria being observed for the first time in 1984. On a biomass
basis, fi. pulicaria was the dominant Cladocera in the lake with a major
bloom in August. However, it was most prominent in the central and
eastern basins. The prevalence of the eutrophic cyclopoid Cyclops
vernal is has decreased within the lake, especially within the central and
eastern basins.
11. A decrease in summer Cladocera and Copepoda abundance in the western
basin Is suggested from 1961 to 1984. Rotifera abundance In the western
basin has increased since 1934. A number of eutrophic rotifer Indicator
species had abundances restricted to or significantly higher in the
western basin. The plankton ratio also suggests a more productive status
for the western basin.
13. There is a lack of dominance of eutrophic rotifer Indicator species
for the entire lake. This suggests that Lake Erie in 1984 as a unit is
not eutrophic. The number of dominant eutrophic algal species has
decreased, while the number of dominant mesotrophic species has Increased;
that is, the trophic ratio has increased, suggesting an improvement in
water quality.
14. Evidence of a shift in trophic status of Lake Erie since 1970 Is
provided by the trophic ratio, the plankton ratio, phytoplankton and
zooplankton indicator species, declines in total abundance and blomass of
total phytoplankton and zooplankton since the mld-60's and 70's, declines
in abundance of nuisance species and eutrophic species, declines in total
phosphorus and chlorophyll .a, and the current total blomass and abundance
of plankton.
15. The trophic condition of Lake Erie appears to be improving. However,
compared to Lakes Huron and Michigan In 1983 and 1984, biomass of
phytoplankton and zooplankton was higher, the plankton and trophic ratios
were lower, and the phytoplankton and zooplankton species compositions
suggest a more productive status for Lake Erie.
16. Based on the classification schemes of Vollenwelder (1968) and
Munawar and Munawar (1982) utilizing maximum and average algal biomass,
the western basin would be meso-eutroph!c, the central basJn mesotrophic,
and the eastern oligo-mesotrophic. This conclusion is supported by other
indicators of the trophic status noted above.
-------
10
17. The decreases in phytoplankton abundance, chlorophyll, total
phosphorus and turbidity are consistent with expectations of long-term
nutrient control. However, the significant changes In the composition of
the zoopIankton community with the appearance and establishment of the
large cladoceran Daphnia pulicarla are attributed to a change In
planktivory. The planktivorous emerald and spottall shiners have
dramatically declined, perhaps due to a resurgence of the walleye and the
salmonfne stocking programs.
-------
11
INTRODUCTION
Nutrient loading of lakes and rivers, navigation, fish management
policies, fishing, shoreline alteration, contaminant production and, in
general, economic development, ultimately affect the lake ecosystem.
Effects of perturbations are not always known and can not always be
monitored individually in large, complex systems such as the Great Lakes.
Biological monitoring is an Integrative monitoring strategy (Johannson et
at. 1985). Ecosystems respond to stress with compensatory changes in
community structure and function mediated at the population level (Boesch
and Rosenberg 1981). Therefore, changes In ecosytem health can be
detected by monitoring changes in the biotic community (Nlcholls et al.
1980, Oil Ion et al. 1978).
Any monitoring program must first document the state of the
ecosystem, namely, the species composition, biomass and production of each
community component, including the normal range of temporal and spatial
variation. The second step Is to examine the relationship and
interactions amongst the ecosystem components in order to interpret and
possibly predict future changes in community structure or function. Thus,
the value of such monitoring programs goes far beyond its surveillance
capabilities; It can form the backbone for research activities, thereby
encouraging a detailed understanding of the system.
This project reported here was initiated by the United States
Environmental Protection Agency, Great Lakes National Program Office
(GLNPO), to analyze phytoplankton and zooplankton samples from Lakes Erie,
Huron and Michigan taken in 1984 and the winter of 1985. Because
phytoplankton are sensitive to water quality conditions and possess short
-------
12
carbon turnover rates, the determination of phytoplankton abundance and
species composition has become established as a method to trace long-term
changes in the lakes (Stoermer 1978, Munawar and Munawar 1982).
Similarly, zooplankton have value as indicators of water quality and the
structure of the biotic community and have proved useful for complementing
phytoplankton to assess the apparent effects of water quality conditions
(Gannon and Stemberger 1978) and of fish populations (e.g. Brooks and
Dodson 1965) on biota. This report represents the second year of similar
samp I ing intensity and pattern of the offshore region of Lakes Erie, Huron
and Michigan.
An in-depth planktonic (phyto- and zooplankton) comparison is
presented based on extensive seasonal lake-wide surveys including the
winter of 1985. This comparison was achieved by the application of
standard and consistent identification, enumeration and data-processing
techniques of plankton that were collected along north-south transects in
Lakes Huron and Michigan and east-west transects In Lake Erie. In
addition, the vertical distribution of phytoplankton was examined In each
lake during the year.
The primary objectives of this report include:
(1) To organize plankton data for use in eutrophication models;
(2) To characterize the composition and abundance of the phytoplankton
and zooplankton for comparison with past conditions to the extent
that they are known;
(3) To provide firm documentation with which future assessment of the
changes In water quality of the lakes can be made;
(4) To characterize the water quality by studying the abundance and
autecology of phytoplankton and zooplankton; and
-------
13
(5) To characterize within and between year plankton variance to allow
better long-term assessments of changes in plankton structure.
-------
14
METHODS
Samp I ing Sites
Phytoplankton and zooplankton samples from Lakes Erie, Huron and
Michigan were collected by GLNPO personnel during several cruises (9-11)
during the spring, summer and autumn of 1984 and the winter of 1985.
Collection dates and station locations of routine plankton sampling are
given in Tables 1 and 2 and in Figures 1 - 3. Locations of sampling sites
on Lakes Michigan and Huron were not seasonally consistent (Tables 3 and
4). By design, alternate east-west stations were sampled (e.g. 5 or 6, 10
or 11; Fig. 1) on various cruises. This selection of sites was based on
previous studies which indicated that adjacent east-west sites were within
homogeneous areas of Lake Michigan (Moll et al. 1985). For analytical
purposes, east-west stations are combined, assuming that no significant
difference in species abundance and composition exist between east-west
stations, to give a single north-south transect. All sites are also part
of the Great Lakes International Surveillance Program.
Chemistry
Only selected water quality variables collected during the study are
presented in this report. Results of the complete water chemistry
investigation are reported elsewhere (Lesht and Rockwell 1987). Methods
used were standard procedures (Lesht and RockwelI 1987).
PhytopIankton
An 8-liter PVC Niskin bottle mounted on a General Oceanics Rossette
sampler with a Guildline electrobathythermograph (EBT) was used to collect
phytopIankton. One-liter composite phytoplankton samples were obtained at
each station by compositing equal aliquots from water samples collected at
-------
15
depths of the surface, 5m, 10m and 20m as allowed by total water depth.
Vertical distribution samples were collected at selected stations from the
surface, 5m, 10m, 15m and 20m (occasionally to 30m).
Phytoplankton samples were immediately preserved with 10 ml of Lugol's
solution, while formaldehyde was added upon arrival in the laboratory. The
settling chamber procedure (Utermohl 1958) was used to Identify (except for
diatoms) and enumerate phytoplankton under phase contrast microscopy at a
magnification of 500x. Objects (spheres < lum, rods < 3um length)
possessing a bluish cast were identified as picoplankton, while those
appearing as dull grey were not counted. The designation Haptophyte spp.
used represents a col lection of morphological forms more appropriately
titled Haptophyceae. A second identification and enumeration of diatoms at
1250x was performed after the organic portion was oxidized with 30? H202
and HNO,. The cleaned diatom concentrate was air dried on a cover slip and
TM
mounted on a slide (75x25mm) with HYRAX mounting medium. Identifications
and counts were done by Dr. Norman A. Andresen, Mr. Mark A. Lamb, Dr. Louis
L. Lipsey, Ms. Heather K. TrulIi and Dr. Marc Tuchman of the Bionetics
Corporation.
The cell volume of each species was computed by applying average
dimensions from each sampling station and date to the geometrical shape
such as sphere, cylinder, prolate spheroid, etc., that most closely
resembled the species form. At least 10 specimens of each species were
measured for the cell volume calculation. When fewer than 10 specimens
were present, those present were measured as they occurred. For most
organisms, the measurements were taken from the outside wall to outside
wall. The protoplast was measured with loricated forms, while the
individual cells of filaments and colonial forms were measured. For
-------
16
comparative purposes, biovolume (urn /L) was converted to biomass (mg/m )
assuming the specific gravity of phytopiankton to be 1.0 (mm /L=mg/m )
(Willen 1959, Nauwerck 1963).
ZoopIankton
A Wildco Mode! 30-E28 conical style net (62-um mesh net; D:L ratio =
1:3) with 0.5m opening (radius=0.25m) was used to collect, where possible,
two vertical zooplankton samples at each station. Vertical tows were taken
from 2m above the bottom to the surface (long tow) and from 20m to the
surface (short tow). The short tow was analagous to an epilimnetic tow in
stratified waters. Filtration volume and towing efficiency were determined
with a Kahl flow meter (Model OOSWA200) mounted in the center of the net.
Filtration efficiency averaged 83.4, 75.9 and 85.8$, respectively, for
Lakes Erie, Huron and Michigan for the entire sampling season. Following
collection, the net contents were quantitatively transferred to 0.5-IIter
sample bottles, narcotized with club soda and preserved with 5% formalin.
Identification and enumeration of zooplankton followed Gannon (1971) and
Stemberger (1979) and were performed by D. Page, H. Trulli and L. Stokes of
the Bionetics Corporation.
Raw counts were converted to number/m by Bionetics, Inc. The volume
of each rotifer species was computed by using the geometrical shape that
most closely resembled the species (Downing and Rigler 1984). It is
essential that the measurements are made on the population being studied
since they vary In different habitats for some species up to 100$ and more
(BottrelI et al. 1976). For each cruise, length of at least 20 specimens
of each rotifer species was measured. Width and depth were also measured
on one date for each lake to develop length-width and length-depth ratios
for use in the simplified formulas of BottrelI et al. (1976). Assuming a
T
-------
17
specific gravity of one, volume was converted to fresh weight and to dry
weight assuming a ratio of dry to wet weight of 0.1 (Doohan 1973) for all
rotifer species except Asplanchna spp. A dry weight/wet weight ratio of
0.039 was used for Asplanchna spp. (Dumont et al. 1975).
Because of the considerable variability In length and thus weight
encountered In the Crustacea, the dry weights of Crustacea were calculated
using length-weight relationships (Downing and RIgler 1984). Average
length of crustaceans (maximum of 20 for each station) was determined for
each station of each cruise. A comparison of calculated weights to
measured weights of Crustacea in Lake Michigan suggests good agreement at
the minimum weight range (Table 5). The use of the mean and the high end
of the range for comparison Is tenuous because they are affected by sample
size and selective feeding of predators. The weight of the Copepoda
nauplil followed Hawkins and Evans (1979).
Data Organization
Abundances and dimensions of each species of phytoplankton and
zooplankton were entered Into a Prime 750 computer using the INFO (Henco
Software, Inc., 100 Fifth Avenue, Waltham, Mass.) data management system.
Blomass was calculated for phytoplankton and zooplankton and placed into
summaries for each sampling station containing density (cells/ml),
biovolume (urn /ml) and relative abundances of species. In addition, each
division was summarized by station. Summary information Is stored on
magnetic tape and is available for further analysis.
Definitions
Common phytoplankton species were defined as having an abundance of
>0.1J8 of the total cells or >0.5$ of the total biovolume.
-------
18
Common crustacean zooplankton species were defined as having >0.1? of
the total abundance or >1.0$£ of the total blomass. Rotifer species were
considered common If they accounted for >1.0$ of the total abundance.
Species diversity refers simply to the number of species observed.
Dominance refers to a community property reflected in the relative
abundance pattern of species. A species was considered to be dominant if
It possessed the highest relative abundance or biomass of a taxonomic
grouping (i.e. division).
Importance refers to a group of measurements by which the species in a
community can be compared (Whlttaker 1975). Abundance or biomass was the
Importance value used In the discussion.
-------
19
RESULTS AND DISCUSSION
LAKE MICHIGAN
Phytop Iankton
Species lists (Table A1) and summary tables of abundance (Table A2)
and biovolume (Table A3) are in Volume 2 - Data Report. A summary of
water chemistry parameters is presented in Table 6.
Annual Abundance of. Major Algal Groups
The phytop Iankton assemblage of 1984 was comprised of 327 species
representing 91 genera from eight divisions. Compared to 1983, a ~A5%
reduction in the number of genera and species was observed. This
difference was mostly attributable to a decrease in the number of
Chlorophyta, Chrysophyta and Cyanophyta (Table 7).
Similar to 1983, the Bad 11ariophyta possessed the largest number of
species (166) and biovolume (70.0$ of the total, Table 8), while the
second largest number of species (63) was observed for the Chlorophyta
(Table 7). The Cryptophyta, as in 1983, accounted for the second highest
biovolume (11.6$) (Table 8). Highest overall densities were attained by
the picoplankton (82.9$ of the total). Both the Pyrrhophyta and the
Chlorophyta had much lower biovolumes in 1984 than in 1983 (Table 8). The
annual average phytop Iankton density and biomass were 22,220+1,400
cells/mL, (mean±S.E.) (29,839 cells/mL, 1983) and 0.55 g/m3±.038
(mean±S.E.) (0.42 g/m , 1983), respectively.
Seasonal Abundance and Distribution of Major Algal Groups
Seasonally, abundance (cells/mL) was low during the spring and had
increased by July. Because sampling in the present study was designed to
monitor the early pre-bloom conditions, the spring bloom observed in May,
-------
20
June and July of 1976 (Bartone and Schelske 1982) was not observed In
1984. A secondary abundance maxima was observed In August (Fig. 4a) but
was not observed in the biovolume seasonal distribution (Fig. 4b). During
August, a general downward trend in biomass occurred. Because samples
were not taken in October, the large autumn peak (48,305 cells/mL) seen in
1983 (Makarewicz 1987) was not observed In 1984. Similarly, a fall bloom
was not observed in 1976 by Bartone and Schelske (1982). This was
attributed either to a weak bloom that was not observed or to the
occurrence of the bloom at a time when samples were not taken.
Considering biovolume, the Baci11ariophyta were dominant throughout
the study period accounting for as much as 80$, but never less than 55$,
of the phytoplankton biovolume (Fig. 5). The overwhelming dominance of
the diatoms throughout the study period precluded the prominent seasonal
succession of algal divisions observed in 1983 (Makarewicz 1987).
The large drop in biovolume of BaciIIariophyta (to -10$) noted in
August of 1983 (Makarewicz 1987) was not observed In 1984. A bloom of
Rh I zoso I en i a er Iejisls during the summer of 1984, not observed in 1983, was
the major cause of the dominance of the diatoms in August (Table 9). For
example, on the 12-14 August cruise, abundance of £. erlens Is was only
17.5 cells/mL, but the biovolume per cell was high. Thus, this one
species accounted for 26.9$ of the total biovolume during the cruise.
The small decrease In diatoms in August of 1984 corresponded with an
increase In the Cryptophyta, while in 1983 the major decline in diatoms
corresponded with an increase in the Pyrrhophyta. A similar shift in
biovolume composition was observed in 1976 with diatoms decreasing to 17$
In August when greens and blue-green algae predominated (Bartone and
Schelske 1982).
-------
21
Regional and Seasonal Trends in the Abundance of Common Taxa
Common species (Table 10) were arbitrarily defined as those
possessing a relative abundance of >0.1$ of the total cells or >Q.5% of
the total biovolume. Forty-three common species were observed In 1984-85
compared to 45 In 1983. Seventy-six percent of the common species
observed In 1984 were also common species in 1983; thirty-one percent of
the common species observed in 1983 were not common in 1984 (Table 11)
(Makarewlcz 1987). The cause of these differences is difficult to
evaluate. Natural annual variability in the lake has never been evaluated
and cannot be evaluated until a longer data set exists. Seasonal sampling
variability exists between 1983 and 1984 and is the most probable cause
for the species differences observed. For example, Dlcthyosphaerlum
ehrenberglanum was a common species for the 1984-85 survey, but not the
1983 survey, by virtue of the inclusion of a winter sampling period in
1984-85. J2. ehrenbergianum was prevalent only In the winter of 1985.
Since no winter samples were analyzed In 1983-1984, this species was not a
common species for the entire 1983 sampling period .
Because of the similarity between the 1984 common species list and
the 1983 Iist, a species by species description of autecology and regional
and seasonal trends are not warranted here and can be referred to In
Makarewlcz (1987). Only new common species are discussed below.
BaciIlarlophyta
Cyc|otella oceI Iata Pant.
Cyclotelia oce11ata was observed in the southern basin of Lake
Michigan in low numbers in 1963 (Stoermer and Kopczynska 1967a). In 1967
this species was most abundant at offshore localities In the northern part
of the lake although occasional populations were noted in the southern
-------
22
basin (Stoermer and Yang 1970). In 1972 Holland (1980) reported this
species as most abundant during the summer (maximum abundance range =
50-70 cells/ml). However, it was not a common species in 1983 (Makarewicz
1987). Cyclotella oceliata is generally abundant in areas of the Great
Lakes which have not undergone significant eutrophication (Stoermer and
Krefs 1980); i.e., associated with oligotrophic conditions In the Great
Lakes (Stoermer and Yang 1970).
In 1984 abundance increased into the summer (mean maximum station
abundance = 39 cells/mL), dropped by mid August and stayed low In late
autumn (Fig. 6a). Mean abundance and biomass were 23.3 cells/mL (0.10$ of
the total cells) and 2.1 mg/m3 (0.38$ of the total biomass) (Table 10). A
maximum abundance of 265 cells/mL occurred on 8-9 July at Station 17.
Mean abundance was high at the most northerly station (77) (45.2 cells/mL)
and at Stations 17 and 22 (46.5 cells/mL) (Fig. 6a, Fig. 9a).
Synedra ulna var. chaseana Thomas
Stoermer and Kopczynska (1967a and b) reported this variety, along
withJS. 111 na var. danica, as reaching 100 cells/mL In early August of
1962. Although several members of the genus occur In Lake Michigan, the
only numerically important taxa were .$_. ul na var. chaseana and _S_. u I na
var. danica in 1962 and 1963, Abundance of this variety was low in 1983
(0.16 cells/mL) (Makarewicz 1987). Stoermer and Yang (1970) characterized
£. ulna var. chaseana as an oligotrophic offshore dominant.
In the present study, a July maximum was observed followed by a
population crash by early August (Fig. 6b). Spring, autumn and winter
abundances were low. Mean density and biomass were 2.2 cells/mL and 17.2
mg/m , respectively. This species represented 3.1$ of the total biomass
-------
23
for the entire sampling period. Maximum abundance was 23 cells/ml at
Station 34 in early July.
Synedra f ?Iiformis Grun.
Earlier work had suggested this species to be largely restricted to
the offshore waters (Stoermer and Yang 1970) and highly oligotrophic
regions such as Grand Traverse Bay (Stoermer et al. 1972). However, it
was fairly abundant in Green Bay in 1977 with an average density of 14.3
cells/ml. Similarly, density averaged 36.9 cells/mL (0,95% of the
population) in the nearshore of southern Lake Michigan in 1977. Average
abundance in 1983 was 2.59 cells/mL (maximum of 25.5 cells/mL).
Abundance was high in April, May and July of 1984 (Fig. 6c). Mean
seasonal abundance reached a maximum of 30.8 cells/mL in July. The
maximum density observed was 118 cells/mL at Station 34 on 7-9 July.
Average abundance and biomass for the non-winter period was 11.2 ceils/mL
and 4.2 mg/m , respectively (Table 10).
Rh izosolenia longlseta Zach.
During 1962 and 1963, R. eriensis was the dominant member of this
genus with a small population of R. graciI is also noted in Lake Michigan
(Stoermer and Kopczynska 1967a). Holland (1980) observed densities of R.
eriensis reaching ~750 cells/mL in 1970 but did not report any other
species of Rhizosotenia. In the 1977 study of Green Bay (Stoermer and
Stevenson 1979), only R, eriensis (maximum = 90 cells/mL) and R. graciI is
(maximum = 46.1 cells/mL) were observed. Similar maximum abundances were
observed for the nearshore zone of southern Lake Michigan [JB. eriensis
(maximum = 81.7 cells/mL); R. gracllis (maximum = 46.1 cells/mL)3
(Stoermer and Tuchman 1979). In 1983, R. eriensis and R. longlseta (R.
-------
24
long!seta = £• graclI is) were observed (Makarewicz 1987). In the present
study, E. long I seta was the more abundant, but £. erTens Is contributed a
greater biomass (Table 10).
£. long I seta abundance was highest in the spring, appeared to
decrease to late July and increased in mid-August. Late autumn and winter
abundances were low (Fig. 6d). Average abundance was 21.2 cells/mL
representing 0.1$ of the total cells and 4.38$ of the total biomass (Table
10).
Nltzsch ia Iauenburgfana Hust.
Stoermer and Kopczynska (1967a), Holland (1980) and Stoermer and
Tuchman (1979) did not report this species in Lake Michigan. Stoermer and
Yang (1970) did not list U. lauenburgtana as a dominant plankton in the
Great Lakes. However, it has been reported as occurring in Green Bay
(mean = 0.41 cells/mL; maximum = 16.1 cells/mL) (Stoermer and Stevenson
1979). In 1983 this species occurred only seven times (mean = 1.36
cells/mL). In 1984 it was a common species by virtue of Its large
biovolume (Table 10). Maximum mean seasonal abundance occurred during the
spring sampling (Fig. 7a).
Chlorophyta
Oocy st i s submarina Lagerh.
Stoermer and Kopczynska (1967a) noted that in 1962 and 1963 the three
most common species of OocystIs were Q. el Iiptlca, Q. submarina and Q.
lacustris. Abundance ranged from 2 to 10 cells/mL. Oocystis spp. was one
of the most abundant taxa observed in August and October of 1977 in Green
Bay (Stoermer and Stevenson 1979). Mean density was 133.8 cells/mL
representing 2.4$ of the population. Similarly, the abundance of OocystIs
-------
25
spp. was relatively high (mean = 30.9 cells/ml; 0.57? of the population)
in the nearshore of Lake Michigan in 1977 (Stoermer and Tuchman 1979).
Q. submarine was observed in 1983 but was not a common species (mean
= 0.2 cells/ml; <.01$ of total population). In the present study, a
maximum pulse of 254 cells/ml was observed, but the average was
considerably lower (mean = 26.5 cells/ml; 0.12$ of the total population)
(Table 10). Abundance was low during the spring and progressively
increased to a peak in late August. Abundance was again low by late
autumn (Fig. 7b). Generally, abundance of Q. submarine was higher at the
northern stations (Stations 64 and 77) and the southern stations (Stations
6, 10, 18 and 22) as compared to the mid-lake region (Fig. 9b).
Dictyosphaerium ehrenbergianum Naeg.
In the 1962-63 study of the southern basin of Lake Michigan,
Dictyosphaerium was observed in the autumn (usually <1 eel1/mL,
occasionally 5 cells/mL) but was not noted in the spring (Stoermer and
Kopczynska 1967a and b). Stoermer and Ladewski (1976) reported the
abundance of this species as being high in 1971 (peaks over 200 cells/mL,
many occurrences over 100 cells/mL). Average abundance In Green Bay in
1977 was 10.3 cells/mL with a maximum of 106.8 cells/mL (Stoermer and
Stevenson 1979).
This was not a common species in 1983 (Makarewicz 1987) and would not
have been in 1984 without the addition of the winter sampling date. In
1984, mean abundance was 23.6 cells/mL (0.11? of the total population)
(Table 10) with a maximum abundance of 298 cells/mL at Station 6 on 7
February 1985. Mean cruise abundance for the February cruise was 105.2
cells/mL. Seasonally, spring abundance was ~25 cells/mL followed by a
decrease into the summer and a major buildup into late autumn and winter
-------
26
(Fig. 7c). Abundance was substantially greater in the southern half of
the lake (Fig. 9c).
Cryptophyta
Cryptompnas rostratiformis Skuja
Little historical Information is available on the distribution or
occurrence of this species in Lake Michigan. Much of the previous work
simply identifies a few major species of Cryptomonas and then lumps the
other occurrences under Cryptomonas sp. For Green Bay, £. marssonIif C.
Pvata, £. erosa and £. gracile were observed in 1977 but apparently not
£• rostratI form is.
In 1983 JQ. rostratiformis was not a common species (Makarewicz 1987).
Abundance was low (1.3 cells/mL, Table 10) in 1984 but biovolume was high
(4.57 mg/m , 0.84$ of total biovolume). Seasonally, abundance was low in
the spring and early summer, increased to -"2 cells/mL In August, and
maintained that level of-^2 cells/mL into February (Fig. 7d).
Cyanophyta
Osc iI Iator!a m1n i ma GIckIh.
Both Ahlstrom (1936) and Stoermer and Kopczynska (1967a) list Q.
mougeot i i as the only species of the genus abundant In their collections.
JQ. J linnet I ca and Q. bornet i i were also observed by Stoermer and Ladewski
(1976). Q. agardh!if Q. Iimnetica, Q. subbrevis, Q. tenuis and Q. m i n i ma
were observed In 1983 (Makarewicz 1987) and 1984. In 1983, Q. IImnetica
and Q. agardhi i were common, while In 1984 Q. 11mnet i ca and Q. m i n i ma were
common.
JQ. minlitp abundance was high in 1984 (mean abundance = 175.5
cells/mL, 0.79? of the total population) (Table 10). Maximum abundance
-------
27
was 4,132 cells/ml at Station 32 on 12 August 1984. Abundance was
greatest during the summer period (F!g. 8). Geographically, abundance
appears greatest at the mid-lake stations (Fig. 9d).
Vertical Distribution
Besides the routine Integrated samples, a vertical series of samples
were taken at two stations (18 and 47) on 15 August 1984 and were not
integrated. Abundance increased with depth at Station 47 and can be
primarily attributed to an Increase In the ptcoplankton (Fig. 10a).
However, BaciIlariophyta, Chrysophyta, Cryptophyta, Chlorophyta and
Cyanophyta also increased with depth (Fig. 10b). With depth, species
diversity Increased. In particular, a 100$+ Increase In diatom species
was observed between the surface and the 10-m depth (Table 12). Species
such as Aster? one I la fprmpsg,, Frag 11 ar I a crotonens i sf Cyclotel I a oce I I ata
(Fig. lOc), Rh izosolenia er?enslsf fi. Iong?setaf Chroomonas porstedtiI,
Rhodomonas ml nuta var. nannoplankticaf Osc11 Iator1 a I linnet lea and JQ.
minima all increased In abundance with depth. One species, Cyclotella
comensis (Fig. 10c), was observed to decrease with depth.
A similar Increase in non-pI cop Iankton species was not observed at
Station 18 (Fig. 11a). In contrast to Station 47, the abundance of the
Baclllariophyta and Cryptophyta dfd not vary In the top 20m of the water
column. The Chrysophyta decreased with depth. All other divisions,
except the Cryptophyta, increased in abundance to the 30-m depth (Fig.
11b). As with Station 47, species diversity of BaciIlariophyta increased
with depth, not to the 20-m depth as In Station 47, but from the 20 to
30-m depth.
The Increase In the abundance and species of diatoms correlates well
with the decrease In temperature associated with the metalImnion (Fig.
-------
28
11b). The appearance of an apparent sub-surface maximum In phytoplankton
abundance is of interest but not surprising. Brooks and Torke (1977),
Mortonson (1977) and Bartone and Schelske (1982) have previously reported
a sub-surface chlorophyll maximum in Lake Michigan. Reasons for the
existence of the layer are not clear and are apparently complex,
encompassing physical, chemical and biological factors (Bartone and
Schelske 1982).
Winter Cruise
Biomass and abundance were low during the winter and not
significantly different from the autumn and spring values (Fig. 4). As in
the non-winter season, the Baci I lariophyta (42.85? of the biomass) and the
Cryptophyta (25.3$ of the biomass) were the dominant divisions. However,
the Cryptophyta accounted for twice the biomass than during the non-winter
season (11.6?).
Stephanodlscus minutus was the dominant winter diatom (mean = 24.2
cells/ml); however, this species was not a common species during the rest
of the year. Other major winter diatoms, FragiI aria crotonensis,
label I aria floculosa and Aster loneI la formosa were common species (Table
10) during the non-winter period.
Dicthyosphaerturn ehrenbergianum was the dominant Chlorophyta.
Seasonally, abundance of this species was low throughout the year and
reached Its peak abundance in winter (93.5 cells/ml). By virtue of its
high winter abundance, It became a common species for the year (Table 10).
Common winter species of Cryptophyta and Cyanophyta were Rhodomonas
minuta var. nannoplanktlca and QsciI later I a 11mnet1ca and m1nIma, which
were also common non-winter species.
-------
29
Historical Changes In Species Composition
Division Trends
Because common species abundance, blomass and distribution are
similar between 1983 and 1984, division and species trends are essentially
the same as those In an earlier report (Makarewlcz 1987) and do not need
to be repeated In detail here. In August of 1962, an analysis of samples
from southern Lake Michigan revealed that the diatoms were numerically
dominant (Stoermer and Kopczynka 1967a). Relative abundance of diatoms
was never lower than ~70? of the total assemblage at all stations. By
1969 green, blue-green and golden brown algae were the major phytoplankton
components (Schelske and Stoermer 1972). Similarly, Schelske et al.
(1971) observed that blue-green and green algae constituted 56 to 85% of
the phytoplankton during August and September. In a detailed study of
southern Lake Michigan, Stoermer (cited in Tarapchak and Stoermer 1976)
observed that blue-green algae contributed up to 80% of the phytoplankton
cells In August of 1971.
By 1977, another shift In algae composition was evident. Relative
abundance of blue-greens dropped to 22.9% In August. However, flagellates
(-42?) rather than diatoms (22$) were the dominant group of algae
(Rockwell et al. 1980). A similar composition as in 1977 was observed in
August of 1984 (diatoms = 12.2%, blue-greens = 16.4?, unidentified
flagellates = 42.1?) if pIce-plankton are not Included in the analysis.
However, in addition to the cyanophytes, both the cryptophytes and
chrysophytes were still numerically more important than the diatoms (Table
8) In 1983, while In 1984 the chrysophytes were. The numerical decline of
the diatoms has been attributed to the high phosphorus loading and
-------
30
concomitant silica depletion (Schelske and Stoermer 1971). On a biomass
basis, however, diatoms were the dominant group in 1983 and 1984.
Species Trends
Changes In common species between 1983 and 1984 are discussed under
Regional and Seasonal Trends In the Abundance of Common Taxa (Page 20).
Dominant diatoms in 1983 Included the numerically dominant Cyclotella
comensiSf FragiI aria crotonensls and Me IosIra itallea subsp. subartlca; on
a biomass basis, Tabe\\ar\a f.ioccuIosa was predominant (Makarewicz 1987).
In 1984 Cyclotel |a comensls and Frag 11aria crotonensls, along with
Cyclotel la oce 11 at .a, were numerical ly dominant. M. Ital I pa subsp.
subarctlca was common but not dominant. On a bfomass basis, Rhizosolenla
erlensls and TabelI aria fIoccuIosa were predominant in 1984.
The Haptophyceae, Monoraphldium contortuji (Chlorophyta), Dinobrypn.
socI aIe var. amer 1canum (Chrysophyta), Rhodomonas minuta var.
nannoplanktica and Chroomonas norstedIi (Cryptophyta), AnacystIs montana.
var. minor and OsciIlatorla I imnetica (Cyanophyta) were numerically
dominant in both 1983 and 1984.
Of the 1983 and 1984 dominant diatoms, only Frag 11 aria crotonensis and
perhaps TabelI aria fIoccuIosa were the major components of the diatom
assemblage In 1962-63. Stoermer and Kopczynska (1967a) noted taxonomic
difficulties with TabelI aria and noted that most populations of TabelI aria
"are probably to be referred to J. fenestrata ...."
The dominant species of CyclotelI a in 1962-63 was £. mlchIganiana.
Rockwell et al. (1980) reported that Cyclotella spp. were common In 1977
but were never dominant. A dramatic decrease in some species of
Cyclotella, such as £. mlchiganlana and £. stelIigera, which were offshore
dominants In August of 1970, was evident (Table 13). CyclotelI a cgmensis.
-------
31
believed to be tolerant of higher nutrient and lower silica concentrations
than most members of thfs genus, was the numerically dominant diatom In
the offshore waters. In 1984, however, Cyclotella oceI Iata, a species
generally associated with oligotrophlc conditions, was also dominant.
Yearly variation in dominance of species of Melosira was evident.
Melosira Island lea was dominant in 1962-63. In 1983 M. islandlca was
present (mean = 12.1 cells/ml), but E. itallea subsp. subarctica (mean =
37.6 cells/ml) was more abundant. In 1984 .M.. Islandlca and M> itallea
subsp. 5ubart?ca had similar abundances (-10-12 cells/mL) (Table 10).
Similarly, Synedra acus was common throughout the southern basin in 1977
(Rockwell et al. 1980) but in 1983 represented only 0.1? of the total
eel Is,
Makarewicz (1987) has suggested an apparent decline in B. eriensls
since 1962. In May of 1962, relatively high (100 cells/mL) populations
were observed in southern Lake Michigan (Stoermer and Kopczynska 1967a).
During May and June of 1970, mean abundances for offshore stations were 63
and 611 cells/mL, respectively (Holland and Beeton 1972). Rockwell et al.
(1980) reported a mean density of 28.7 cells/mL for R. eriensls during
June of 1977. Abundance in 1983 was 2.6 cells/ml for the entire lake. A
bloom (133 cells/mL) in the northern Station 77 did occur In October. In
1984-85, mean lake abundance increased to 18.2 cells/mL. Similar to
species of Meloslraf considerable yearly variation in abundance of
Rhlzpsolenla from 1983 to 1984 was observed.
Anklstrodesmus falcatus Increased In abundance to 1977 and had
decreased by 1983. Ahlstrom (1936) reported this species as rare, but
Stoermer and Kopczynska (1967a) noted that it had Increased by 1962-63
(range = 20-60 cells/mL). Rockwell et al. (1980) suggested that by 1977
-------
32
it had increased further (range = 20-160 cells/ml). In 1983 this species
was observed only once during the study at Station 32 (6.5 cells/ml).
This species was not observed in 1984.
Dominant chrysophytes in 1962-63 were Dinobryon divergeng, J3.
cylindricum and Q. soc i aIe (Stoermer and Kopczynska 1967a). Rockwell et
al. (1980) reported them as dominant or subdominant offshore. With the
exception of £. cyl indricum In 1984, I>. divergens, ]). cyl indricum and D.
soc?aIe were common species in 1983 and 1984. However, the haptophytes
were numerically the dominant group within the chrysophytes in 1983 and
1984.
Dominant cryptophytes in 1983 and 1984 included Cryptomonas erosa
var. refIexa, £. _e_co_sfl and Rhodomonas minuta var» nannoplanktica.
Stoermer and Kopczynska (1967b) and Stoermer (1978) reported these species
as uncommon in Lake Michigan, but Vollenweider et al. (1974) noted these
species as commonly found. Similarly, Munawar and Munawar (1975), Claflin
(1975) and Rockwell et al. (1980) had reported £. .exQSa and £. minuta var.
nannopIanktica to be dominant, abundant and perhaps increasing in number.
From the 1983 and 1984 study, It is apparent that £. erosa was numerically
uncommon but on a biomass basis was the second most Important cryptophyte
(Table 10). Evaluation of abundance of £. minuta In earlier studies was
not possible because it was grouped into phytoflagellates, flagellates or
simply Rhodomonas. What can be reported about Rhodomonas minuta var.
nannoplanktica is that in 1983 and 1984 It was the dominant cryptophyte on
a numerical basis.
Oscillator I a Itmnetlca has become more prevalent In the lake.
Ahlstrom (1936) and Stoermer and Kopczynska (1967a) listed £. mougeot11 as
the only species of this genus abundant In their collections. Stoermer
-------
33
and Ladewski (1976) reported that Q. I fmnetTea had generally Increased In
abundance in Lake Michigan. Rockwell et al. (1980) observed that Q.
11mnet1ca was common throughout the basin In April and June and was
especially abundant in September of 1977 at certain stations. Not
considering the pI cop Iankton, which were not counted In previous studies,
Q. I 1mnetic§ was the numerically dominant offshore blue-green algae In
1983 (Makarewicz 1987) and was second In abundance in 1984 (Table 10).
Anacystls montana var. minor was the dominant blue-green algae In 1984
(Table 10).
PJco.plan.Kt.Q-n
4
Picoplankton abundance In 1984 (mean = 18,409; maximum of 4.3 x 10
5
cells/ml) was not dissimilar from 1983 (mean = 23,607; maximum of 1 x 10
cells/ml). On a numerical basis, the plcoplankton represented 82.856 of
the total cells in 1984. Their dominance of the phytop Iankton community
in 1984 was comparable to that In 1983 (89.4? of total cells). Prior to
the 1983 study (Makarewicz 1987), no other researchers on Lake Michigan
have routinely reported this group of organisms. Because of the
overwhelming dominance of this group, analysis and discussion of this
group would be facilitated with verification of the systematics of the
spheres (Anacystls marina?), rods (Coccochloris pentocystis?) and the
spherical-fI ageIlates.
Geographical Abundance and Distribution
Average phytopIankton abundance for the non-winter sampling period
generally decreased from the north (Station 77) to the south at Station 57
(Fig. 12). Overall abundance remained roughly the same southward to
Station 18. At the most southerly sampling station (Station 6), abundance
-------
34
was higher than In the rest of the lake except for the most northern
stations (Station 77 and 64). Thfs pattern is not dissimilar from the
geographical pattern observed in 1983 for Lake Michigan (Makarewicz 1987).
This abundance pattern is attributed mainly to the picoplankton, the
BaciIlariophyta and the Cyanophyta which all have higher abundances at the
northern stations. The higher abundance at Station 6 was caused by the
picoplankton. The peak in abundance of the Cryptophyta at Station 41 in
1983 (Makarewicz 1987) was again observed in 1984 but was not as prominent
as in 1983. A peak in Chlorophyta at Station 41 was not observed in 1984
as it was In 1983. Cyanophyta were in higher abundance at the northern
stations (77 and 64) and at Stations 41-27 (Fig. 12).
Seasonally, the spring and autumn cruises possessed a geographical
abundance pattern similar to the mean annual phytopIankton distribution
with abundance peaks at the northern (Stations 64 and 77) and southern
(Station 6) stations (Fig. 13). Abundances of BaciIlariophyta, Cyanophyta
and picoplankton peaked at these stations. Only on the 27-29 November
cruise did a maximum in abundance not occur at Station 6. The summer
cruises did not display the distinctive northern and southern peaks
observed in the spring and autumn of 1984. Similar geographical peaks in
abundance were observed at the northern and southern stations In 1983
(Makarewicz 1987).
Interestingly, many of the same species had distinctly higher
abundances in 1983 and 1984 at the northern and southern stations.
TabeI Iar ja f locculosa, Fragt I aria crotonensls, Cyclotel la comensis,.
Coelasphaerturn naegellanum and picoplankton were more abundant at the
northern stations than in the rest of the lake in 1983 and 1984. In
addition, Oocystis submarine was abundant in 1984, while Cyciotella comta,
-------
35
Chroomonas norstedt I i and OsciI later I a agardh i i had a greater abundance at
the northern stations 64 and 77 In 1983. Except for £. comensis,, whose
ecological affinities are poorly known, the other diatom species more
prevalent at Stations 64 and 77 are generally associated with mesotrophic
conditions.
Besides picoplankton, the abundance peak at Station 6 in both 1983
and 1984 was attributed to DInobryon soc?aIe var. americanum and J).
divergens. Species of haptophytes prevalent at Station 6 in 1983 were not
prevalent in 1984.
The northern stations 64 (depth = 25m) and 77 (depth = 23m) and the
southern station 5/6 (mean depth = 50m) are best described as nearshore
stations Cdepths are less than or equal to 50m (Bartone and Schelske
1982)3. The physical and chemical characteristics of the nearshore and
the Straits of Mackfnac stations differ significantly from the open lake
stations (Bartone and Schelske 1982). Thus the differences In
phytoplankton abundances observed at the northern and southern stations in
this study should be related to known differences in water quality. There
is some evidence to support this hypothesis. A comparison of nutrient
data from the nearshore and offshore stations indicates that total
phosphorus was higher at Station 64 and silica was higher at Station 77
compared to the rest of the lake (Table 14). Station 6 had nutrient
levels similar to the rest of the lake.
Temperature may also be a factor in the occurrence of the geographic
abundance peaks observed. For example, on 6 and 7 May the higher
temperatures and abundances at Stations 6, 64 and 77 correlate well (Fig.
13).
-------
36
Indicator Species
Stoermer and Yang (1970), in a comparison of modern and historic
records, reported that taxa characteristic of disturbed situations were
rapidly Increasing in relative abundance in Lake Michigan in the 60's. In
the nearshore area, a shift In oligotrophlc forms to those which dominate
under eutrophlc conditions was evident. Occurrence of certain eutrophlc
species was also evident In offshore waters (Stoermer and Yang 1970).
Dominant diatom species In the offshore waters In 1983 were
Cyclotel la comensIs, £• comtar Tabel I aria f locculosa. Frag 11 aria
crotonensis and Meloslpa .Itai.l.ca subsp. subartlca. The same five diatoms
were dominant In 1984 with the exception of £. £Qffi±fl and the addition of
Rhtzosolenla erlens Is and Cyclotella ocellatg (Table 10). In fact, £.
erlensls accounted for ~25% of the total blomass of phytoplankton during
1984.
Rhlzosolenlg erlensls may be an opportunistic species which is able
to rapidly develop fairly high abundances when conditions are favorable
(Stoermer and LadewskI 1976). Stoermer and Yang (1970) listed £. erlensls
with the ollgotrophlc offshore dominants, which includes £. QgeUataf but
noted that B« erlensls seemed to occur In greater abundance In areas that
have received some degree of nutrient enrichment. TabelI aria fIoccuIosa
and £. crotonensis are mesotrophic forms, while the ecological affinities
of £. comens1s are poorly understood. CyclotelI a comensIs was formerly
found in primarily ollgotrophlc areas (Stoermer and Stevenson 1979) under
some nutrient stress (Stoermer and Tuchman 1979). Compared to the 1983
cruises (Makarewlcz 1987), where mesotrophic forms were predominant, the
same mesotrophic forms were present In 1984 along with ollgotrophlc
indicators.
-------
37
The indicator diatom species and the distribution of them (trophic
ratio) (Table 15) suggest a eutrophic status for nearshore waters In 1977,
while the offshore waters in 1970-71, 1983 and 1984 would be in the
oligotrophic-mesotrophic range. With the high mesotrophic/eutrophlc ratio
in 1970-71 (M/E = 8) as compared to 1983 and 1984 (M/E = 4), It is
tempting to suggest a slightly more mesotrophtc status in more recent
years. At best, this observation has to be viewed with caution since only
one species difference is required to achieve the observed change. The
M/E ratio has to be interpreted conservatively as it is Influenced
somewhat by the definition of the dominant species (e.g. 1$ of biomass)
utilizied. Nevertheless, the trophic status as determined by Indicator
species and the M/E ratio agrees well with the 1976 assessment based on
particulate phosphorus concentrations that place the open lake waters of
Lake Michigan in the oligotrophic-mesotrophic range (Bartone and Schelske
1982).
Histprical Changes In Community Abundance
A comparison of abundance trends over the entire lake was not
possible because of the lack of comparable offshore data prior to 1983.
Figure 14 plots the 1962-63 and the 1976-77 data of Stoermer and
Kopczynska (1967a and b) and Rockwell et al. (1980), which are
representative of the southern portion of the lake. Only a range of
abundance is available for 1962-63, while the mean, standard error and
range are plotted for the other data. Because plcoplankton were not
counted prior to 1983, they are removed from the 1983 and 1984 data
presented In Figure 14. Although a mean is not available, it is apparent
that abundance increasd from 1962-63 to 1976-77. From 1976 to 1983 and
1984, abundance was not significantly different (P=0.05). Based on the
-------
38
classification scheme of Munawar and Munawar (1982), which utilizes the
mean phytopIankton biomass as an Indicator of trophic status, Lake
Michigan would be classified as ollgotrophtc in 1984. This designation Is
supported by the trophic ratio and composition of indicator species.
-------
39
LAKE MICHIGAN
ZoopIankton
Annual Abundance of ZoopIankton Groups
Species lists (Table A4) and summary tables of abundance (Table A5)
and biomass (Table A6) are in Volume 2 - Data Report. The zoopIankton
assemblage of 1984 comprised 52 species representing 34 genera from the
Calanoida, Cladocera, Cyclopotda, Harpacticoida, Mysidacea and Rot ifera.
Compared to 1983, reductions of 21% and 24% in numbers of genera and
species, respectively, were observed. This difference is mostly
attributable to a decrease in number of Cladocera and Rot ifera.
The Rot ifera possessed the largest number of species (29) and
relative abundance (67.5?) followed by the Cladocera (10 species) which
accounted for 39.8$ of the zoopIankton biomass (Table 16). The Rot ifera
contributed only 2.6% of the total biomass (Table 16). Average density
and biomass for the study period was 59,764±8,284 organisms/m (mean±S.E.)
(1983 = 69,353) and 33.2+4.9 mg/m3 (mean±S.E.) (Table 6).
Seasonal Abundance and Distribution of Major ZoopIankton Groups
The seasonal abundance and biomass pattern were virtually identical
(Fig. 15) with a maximum in August. The secondary maximum observed in
October of 1983 (Makarewicz 1987) was not observed in 1984. This major
difference between 1983 and 1984 is apparent and is probably related to
the difference in the seasonal samp I ing pattern between years. Samples
were not taken in September and October of 1984. A sampling pattern
including the June-July and September-October period is required to fully
evaluate the differences in the seasonal distribution pattern.
Seasonally, abundance and biomass of all groups were higher in August
as compared to the early spring and late fall (Figs. 16 and 17). In 1983
-------
40
a peak in rotifer abundance occurred In October (Makarewicz 1987), which
was not observed In 1984 due to a lack of October samples. The high
abundance of Cyclopolda, Calanoida, Cladocera and Copepoda nauplii in
August of 1984 was not observed in 1983 (Makarewicz 1987).
Geographical Abundance and Distribution of Zooplankton Groups
A definite trend of increasing zooplankton abundance occurred from
south to north In Lake Michigan (Fig. 18). Zooplankton abundance at the
far northern Stations 64 and 77 was higher than in the rest of the lake.
Abundances of Rotifera, Cladocera and Copepoda nauplii were all higher at
these far northern stations. Biomass, however, was similar southward from
Station 77 to Station 18, after which biomass decreases southward (Fig.
19). These patterns were not observed In 1983 (Makarewicz 1987).
Abundance of Diaptomus sic!I is was higher In southern Lake Michigan
(Makarewicz 1987) in 1983. However, a similar pattern was not evident
(Fig. 20) in 1984. Copepodites of Diaptomug averaged a higher abundance
in southern Michigan. Similar to 1983 was the increase in Cladocera
abundance at the far northern stations (Fig. 19). Abundance of Posmipa
jongirostris dramatically increased at these stations In 1983 and 1984
(Fig. 21). Also, Eubosmina cgregoni, Notholca laurentiaef &. squamula, M.
foliacea and HoI opediurn gibberurn a I I had abundance peaks at the far
northern end of the lake In 1983 and 1984 (Fig. 22). Polyarthra vuigaris
and £. remata had higher abundances in 1984 only at the northern Stations
64 and 77 (Fig. 22).
Common Species
Common Crustacea species (Table 17) were arbitrarily defined as those
possessing a relative abundance of >0.1$ of the total abundance or 1.0$ of
-------
41
the total biomass, Rotifera species were considered common if they
accounted for >1.0/£ of the total zooplankton abundance or biomass. The
number of common species (1983 = 25 species; 1984 = 24 species) and common
species composition were essentially the same between 1983 and 1984.
Rotifer composition differed with NothoIca fo1iaceaf &. laurentiae and
Polyarthra remata being common In 1984 only, while £. major, £.
doIIchoptera, Keratella crassa and j£. earlinea were common in 1983.
Historic Changes in Species Composition
Crustacea
Numerous recent studies (Williams 1966; Johnson 1972; Gannon et al.
1982a, 1982b; Evans et al. 1980) of the nearshore region of Lake Michigan
exist, along with data from as far back as 1927 (Eddy 1927). Several
researchers have compared the nearshore with the offshore zooplankton In
discussions of eutrophication of the entire lake. Comparisons of the
inshore with the offshore stations should be viewed with caution because
effects are not necessarily due to eutrophfeat ion or fish predation (Evans
et al. 1980).
Although no intensive zooplankton studies of the offshore waters of
the entire lake basin have taken place, some offshore studies of Lake
Michigan zooplankton do exist. Wells (1960, 1970) sampled Crustacea with
a number 2 (366um) net on four dates in June, July and August in 1954,
1966 and 1968 from the offshore region off Grand Haven, Michigan. On six
dates (March 1969 to January 1970), Gannon (1975) collected crustaceans
with a 64-um mesh net from the offshore and Inshore of Lake Michigan along
a cross-lake transect from Milwaukee to Ludington. In September of 1973,
northern Lake Michigan was sampled with a 250-um mesh net (Schelske et al.
-------
42
1976). Also, Stemberger and Evans (1984) provided abundance data (76-um
net) for a few zooplankters from offshore waters of the southeastern Lake
Michigan area.
The data of Wells (1960, 1970) and Gannon (1975) are useful but have
to be used with caution. A 366-um and a 250-um net are probably
quantitative for larger crustaceans but certainly would not be for smaller
crustaceans such as Chydorus sphaericus, Bosmina longirostris,. Eubosmina
coregon i f Ceriodaphnia spp., Tropocyclops prasinus and copepods
(Makarewicz and Likens 1979).
The zooplankton populations in Lake Michigan underwent striking
size-related changes between 1954 and 1966 (Wells 1970). Species that
declined sharply were the largest cladocerans (Leptodora kindti?, Daphnia
galeata mendotae and Q.. retrocurva), the largest calanoid copepods
(L imnocgl anus macrurusj. Epischura Iacustris and Diaptomus sici I is) and the
largest cyclopoid copepod (Mesocyclops edax). Medium-sized or small
species (£. longiremisr JU. gibberum, Polyphemus pediculus, Bosmiaa
longirostriSf Ceriodaphn ia sp., Cyclops bicuspidatus, Cyclops vernal \.sr
D i aptomu s ash I an d i) increased in number, probably in response to selective
alewife predation. After the alewife dieback, J^. eda?< and D. galeata
mendotae were still rare in 1968 when the composition of the zooplankton
community shifted back toward one similar of 1954 (Wells 1970).
In northern Lake Michigan during September of 1973, predominant
species were Daphni a galeata mendotae, Q. retrocurvaf L imnocalanus
macrurusf Pi aptomu s oregonensis,. Eubosmi na coregon i and Diaptomus sici I is.
Cyclopoid copepods were a minor component of the fauna in 1973 (Schelske
et al. 1976).
-------
43
The changing nature of the zooplankton community of Lake Michigan was
evident in 1983. Daphnia gal eata mendotae, D. pulicaria and D. retrocurva
were the second, third and fourth most abundant cladocerans in the lake
(Makarewicz 1987). Q. galeata mendotae and D. retrocurva were again the
prominent daphnids in 1984 along with the dominant cladoceran Rosmina
longirostris. Abundance of Daphnia pul icaria dropped from an average of
376/m3 in 1983 to 78/m3 in 1984. In August of 1983, abundances of JD.
galeata. rare in 1966 and 1968, were half of those in 1954 (1,200/m3) and
three times the 1954 abundance In 1984 (Table 18).
The 1983 abundance of Daphnia retrocurva was similar to the August
1966 abundance rather than to those of 1954 or 1968. However, maximum
abundance in October of 1983 (3,161/m ) was comparable to the 1954 or 1968
observations. Perhaps related to the low abundance of D. retrocurva in
August of 1983 was the appearance of the large (-*2 mm) (Evans 1985)
cladoceran Paphnia pul icaria,. which reached a maximum abundance In August.
When .Q. pulicaria dropped in abundance in 1984, £. retrocurva abundance
increased to a density comparable to those of 1954 and 1968 (Table 17).
Evans (1985) recently reported that Q. pulicaria was first observed
in Lake Michigan in 1978. Abundance remained low in southeastern Lake
Michigan until 1982 and 1983 when they dominated the offshore summer
Daphnia community and at an offshore station southeast of Grand Haven,
Michigan. In 1983 this species was the dominant cladoceran in the
offshore waters of Lake Michigan from the short and long hauls. Mean
station abundance reached 1,741 organisms/m in early August with a
maximum of 6,056/m . In 1984, abundance of D. pulicaria dropped to a mean
of 248/m3 from 1011/m3 in 1983 (Table 18).
-------
44
The occurrence of Daphnia .d_ub_La, a new species observed in 1983, was
not confirmed in 1984. In a review of the 1983 material by a different
taxonomist, this species was not observed.
The large cladoceran Leptodora k indti i appears to be steadily
increasing in abundance since 1954 in Lake Michigan (Table 18). Eubosmlna
coregon i f B. longirostrig and the larger Ho I oped 1 urn gibberum have also
increased in abundance since 1954 (Table 18). The increase in U. gibberum
was probably real. It is doubtful that this large cladoceran would pass
through a 366-um mesh net like that used in Wells (1960, 1970) studies of
1954-68. However, the net employed by. Wells' would not have been
quantitative for £. coregon i and £. longirostris.
Cyclops bicuspidatus was the dominant cyclopoid in 1983 and 1984 with
Diaptomus ash I andj being the dominant calanoid in 1983 (Makarewicz 1987)
and £). siciI is in 1984 (Table 17). Abundance of Mesocyclops edax was low
in August of 1983 and 1984 compared to 1954, but abundance in early
October of 1983 reached a comparable 151 organisms/m (mean station
abundance). Diaptomus minutus appears to have decreased in abundance
since 1968, while JD. oregonensis abundance remained similar to 1954 (Table
19). D. siciI is has increased steadily since 1968. Abundance of
Limnocalanus macrurus was lower during August of 1983 than in 1954-68.
However, abundance in 1984 was similar to 1954 and 1966. The abundance of
Epischura lacustris in August was still low in 1983 and 1984 relative to
1954, but reached 111 organisms/m (mean station abundance) in late
Octoberof 1984.
By 1983 and 1984, the large cladocerans, calanoids and cyclopoid
copepods, observed by Wells (1970) to have decreased sharply in the early
60's, had increased in abundance to densities similar to those in August
-------
45
of 1954. In some instances, abundance was not as high in August but was
as high at other times of the year. In addition, a new large cladoceran,
Daphnia pulicaria, has become estabiished in the offshore waters of Lake
Michigan.
The resurgence of larger zooplankton in Lake Michigan is probably
related to the sharp decline in the abundance of the planktivorous alewife
in 1982 and 1983. The lakewide catch of adult alewifes was only 31% of
that of 1982 and only 12$ of the 1981 catch. Bloater chubs are replacing
the alewifes and have been experiencing a dramatic increase in abundance
since 1970 (Wells and Hatch 1983). Bloaters above ^18 cm in size
primarily feed on _My_s_Ls and Pontoporeia. Only smaller individuals feed on
zooplankton (Wells and Beeton 1963).
Rot ifera
Rotifer studies reported in the literature are primarily from the
nearshore region of the lake. In the nearshore, KeratelI a cochlearis,
Polyarthra vulgar is, KeI Itcott i a longispina, Synchaeta sty I ata and
gynchaeta tremuI a were dominant in 1926-27 (Eddy 1927). Keratella and
Polyarthra were the dominant genera in 1962 (Williams 1966), while £.
cochlearis and £. vulgar is were dominant in 1970 (Johnson 1972). Gannon
et al. (1982a) noted that the following rotifers were predominant in 1977:
Keratella cochlear?sf JK. crassaf Conochi1 us unicorn is, KeI I? cott i a
longispina, Polyarthra vulgaris and £. remata.
Abundance of rotifers in Lake Michigan generally decreased from the
nearshore into the offshore (Gannon et al. 1982a, Stemberger and Evans
1984) although the species composition of the nearshore and offshore was
relatively similar. In 1983 the predominant offshore rotifers were in
descending order: Polyarthra vulgar is, Synchaeta sp., KeratelI a
-------
46
cochI earisf Polyarthra major, KeI Ii cott i a longisp Fnaf Keratella crassaf
Gastropus sty lifer and Colletheca sp. (Makarewicz 1987). The predominant
rotifers in 1984 were KeratelI a cochI ear\st KeI Ii cott i a long!spinaf
Polyarthra vulgar is and Synchaeta sp. (Table 17). Both the 1983 and 1984
dominant rotifer composition is similar to the nearshore and to Ahlstrom's
(1936) offshore observations of predominant species (Keratella cochlearis,
gynchaeta sty I ata and Polyarthra vulgaris).
Historical Changes in Zooplankton Biomass
Offshore crustacean zooplankton biomass data is available from 1976
(Bartone and Schelske 1982) for northern Lake Michigan. No information is
presented on sampling intensity or technique. A comparison with 1984
(Table 20) reveals that no significant difference in crustacean biomass
exists between 1976 and 1984.
Another longer sequence of data is described by Scavia et al. (1986).
Except for 1977, 1982, 1983 and 1984, zooplankton samples were primarily
from an offshore station (40-m depth) west of Benton Harbor, Ml. A
comparison of the mean offshore 1984 lake-wide biomass data to Scavia's
station indicates good agreement (Fig. 23). From Figure 23, there appears
to be no obvious trends in zooplankton biomass.
Indicators of Trophic Status
Zooplankton have potential value as assessors of trophic status
(Gannon and Stemberger 1978). Rotifers, in particular, respond more
quickly to environmental changes than do the crustacean plankton and,
therefore, are more sensitive indicators of changes in water quality.
Composition of the rotifer community (Gannon and Stemberger 1978) can be
used to evaluate trophic status.
-------
47
In 1983 the six predominant rotifers in descending order of relative
abundance were £. vulgar is, Synchaeta sp., J<. cochI ear is, £. major, K.
longlspina and C. unicornis, while in 1984 the predominant rotifers were
J<. cpchlearis, J£. longisp inaf £. vulgaris and Synchaeta sp. The 1983 and
1984 rotifer composition suggests an oligotrophic association. A rotifer
community dominated by Polyarthra vulgaris, Keratella cochI ear is,
ConochiI us unicornis and Ke|Iicottia longisp ina has been considered to be
an association indicative of an oligotrophic community by Gannon and
Stemberger (1978).
The high relative abundance of Diaptomus slciIis and Limnocalanus
macrurus (Table 17) and the occurrence of Senecel I a cal anoides, al I
oligotrophic indicators (Gannon and Stemberger 1978, McNaught et al.
1980), also suggested oligotrophic offshore conditions for the entire
lake.
The calanoid/cyclopoid plus cladoceran ratio has been used as a
measure of trophic status in the Great Lakes (Gannon and Stemberger 1978,
McNaught et al. 1980). Calanoid copepods generally appear best adapted
for oligotrophic waters, while cladocerans and cylopoid copepods are
relatively more abundant in eutrophic waters. On the north-south
transect, the plankton ratios were high and similar, except at the far
north and the southern extreme of the lake (Table 21). This pattern was
repeated in 1984 and suggests that a lower quality of water occurred south
of Station 18 and north of Station 57. The eutrophic rotifer indicator
species Trichocerca pusi I I a was observed exclusively at Station 6,
reinforcing the Idea that a lower water quality exists at Station 6.
Similarly, Trichocerca multicrinis, a eutrophic indicator, was prevalent
at northern stations.
-------
48
The low plankton ratios (0.20 - .41; Table 21) at the far northern
end of Lake Michigan (Stations 64 and 77) were very similar to those
observed in 1973 at the Straits of Mackinac (Gannon and Stemberger 1978).
Gannon and Stemberger (1978) implied that more eutrophic conditions exist
within this area of a low calanoid to cladoceran plus cyclopoid ratio.
Abundance of the ol igotropic L imnocalanus macrurus and Diaptomus siciI is
was significantly lower in these far northern stations, while Eubosmina
coregoni and Bosmina long?rostris, often associated with more productive
conditions, increased at the far northern stations (Fig. 21). In
addition, several mesotrophic algal species were more predominant at the
northern stations.
Notholea fol iacea is often associated with ol igotrophic conditions
(Gannon and Stemberger 1978). In this study, several indicators suggest
that the northern end of Lake Michigan near the Straits of Mackinac has
waters associated with more productive conditions. Yet abundance of
Nptholca fol iacea increased at the northern stations. The use of U.
fol iacea as an ol igotrophic indicator has to be viewed with caution.
With a zooplankton abundance between those of Lakes Erie and Huron
(Table 6), the presence of an oligotrophic rotifer association, a plankton
ratio between those of Huron and Erie, the domination of the calanoids and
the fairly abundant presence of the ol igotrophic indicator species
Diaptomus sfciI is and L imnocalanus macrurus, the offshore waters of Lake
Michigan in 1984 are best characterized as mesotrophic/oligotrophic. A
similar conclusion utilizing zooplankton abundance and species composition
was drawn in 1983. Phytoplankton composition and abundance and water
chemistry suggest a similar trophic status (This Study).
-------
49
Trophic Interactions
Between 1975 and 1984, gradual declines In spring total phosphorus
and summer ep I limnetic chlorophyll .a are reported (Scavia et al. 1986).
However, long-term changes of phytopl ankton and zooplankton biomass are
not apparent in this study. Perhaps, the minimal changes observed in
chlorophyll a are not reflected in the high variability phytoplankton and
zooplankton estimates. Scavia et al. (1986) points out that the changes
in total phosphorus and chlorophyll .a are consistent with expectations of
nutrient load control.
However, the significant lake-wide changes in zooplankton and
phytoplankton composition may not be expected from nutrient control. A
species new to the plankton assemblage, Daphnia pul icaria, is at least a
sub-dominant organism within the offshore. In addition, Leptodora
kindti I, Daphnia galeata mendotaef Diaptomus ashjajidl and Cyclops
have returned to and exceeded abundances observed in 1954
during a period of low alewife abundance.
Scavia et al. (1986) suggests that predatory pressure from alewife
suppressed large-bodied zooplankton until the early 1980's. Decline of
the alewife population as the major forage fish (Jude and Tesar 1985,
Wells and Hatch 1983) has been linked to the increasing population of
stocked salmonines in Lake Michigan (Stewart et al. 1981, Jude and Tesar
1985). The decrease In alewife abundance has reduced size-selective
predation on larger zooplankton allowing larger zooplankton to return
(Scavfa et al. 1986, Wells 1970, Kltchell and Carpenter 1986).
Table 22 lists correlation coefficients of phytoplankton abundance
versus total phosphorus and zooplankton for each cruise. For each cruise,
11 stations covering the entire length of the lake were sampled over a
-------
50
short period of time. Interpretations of the correlations were as
follows: A negative correlation between a zooplankton group and
phytoplankton implied grazing pressure on phytoplankton, while a positive
correlation between total phosphorus and phytoplankton abundance would
suggest an enhancement of phytoplankton abundance due to phosphorus
availability. Except for the early winter cruise, correlation of total
phosphorus to phytoplankton abundance was weak as compared to Lake Erie
(Table 22). Grazing pressure appeared to be particularly heavy during the
May series of samples.
As suggested by Scavia et al. (1986), .Q. pulicaria appears to have a
negative impact on phytoplankton abundance expecially during mid-August.
Interestingly, when Daphnia galeata mendotae is added to the correlation
analysis, the correlation coefficient increases from -.27 to -.50
suggesting that Q. galeata mendotae is also having a major effect on
phytoplankton abundance during August. This would be an added effect in
that D. galeata has increased since 1954 apparently in response to
decreased selective pressure by the alewife. The calanoids appear to
exert grazing pressure in the spring and early winter as opposed to the
summer (Table 22).
The causes of the changes in species composition of phytoplankton are
much more difficult to evaluate. Changes in herbivore species composition
could affect algal species composition. Certain zooplankton feed on a
wide variety of algae of different sizes and shapes, and with or without
sheaths (Gliwicz 1980, McNaught et al. 1980b, Porter and Orcutt 1980).
Other zooplankton are highly selective in the algal types ingested.
Cellular forms are ingested more readily than filamentous or spinuosus
forms and zoopIanktonic filtration rates, growth and survivorship are
-------
51 ,
greater when feeding on cellular forms (Porter 1973, Arnold 1971).
Selective grazing and utilization can remove species or reduce population
size in the algal community. Alternatively, grazer utilization of an
algal species can result in enhancement of primary productivity of that
species by increased selection for faster growing genotypes (Crumpton and
Wetzel 1982).
In summary, zooplankton community structure is important in
determining the responses of algal assemblages to grazing (Bergquist et
al. 1985). Small algal taxa increase in abundance when grazed by small
zooplankton, but decrease in density when grazed by large zooplankton.
Conversely, large phytoplankton become less abundant in the presence of
small zooplankton, but increase in density in the presence of large
zooplankton (Bergquist et al. 1985). Perhaps the increase in abundance of
the large d i atom Rh i zosoI en i a spp. during the summer of 1984 is related to
increased grazing pressure of large Daphnia
Nutrient effects can also affect composition of phytoplankton. For
example, Asterione I I a is a successful competitor at high Si/P ratios,
FragiI I art a can dominate at intermediate ratios and Stephanodiscus grows
well when Si/P ratios are low (KM ham and KM ham 1978j Kilham and Til man
1979; Tilman 1978, 1980). At high Si/P ratios, diatoms can effectively
out compete blue-green algae (Holm and Armstrong 1981). Similarly, as
silica is reduced and combined nitrogen declines, green algae can compete
less effectively with nitrogen-fixing blue-greens (Smith 1983). Effects
on phytoplankton composition from both top-down and bottom-up routes are
expected but are difficult to separate in this descriptive study.
-------
52
LAKE HURON
PhytopIankton
Species lists (Table A7) and summary tables of abundance (Table A8)
and biovolume (Table A9) are in Volume 2 - Data Report. A summary of
water chemistry parameters is presented In Table 6.
Annual Abundance of Major Algal Groups
The phytoplankton assemblage of 1984 was comprised of 315 species
representing 92 genera from eight divisions (Table 23). Compared to 1983,
a 4.3$ reduction in the number of species and a 4.5% increase in the'
number of genera were observed.
The annual average phytoplankton density and biovolume were 17,209
cells/ml (19,147 cells/ml; 1983) and 0.38 mm3/L (0.42 mm3/L; 1983),
respectively. Similar to 1983, the BaciIlariophyta possessed the largest
number of species (156) and biovolume (61.9$ of the total, Table 24),
while the second largest number of species (64) was observed for the
Chlorophyta (Table 24). Although the relative biovolume of the
Cryptophyta in 1984 (9.1$) was similar to 1983 (8.3$), their relative
importance dropped from second to third (Table 24). The Chrysophyta
accounted for the second highest biovolume (9.45$). Highest overall
densities were attained by the picoplankton (83.9$ of the total). Both
the Cyanophyta and the Chlorophyta had lower average blovolumes in 1984
than in 1983, while Pyrrhophyta biovolume increased (Table 24).
Seasonal Abundance and Distribution of Major Algal Groups
Seasonally, abundance (cells/mL) and biovolume (mm /ml) increased
from April to a maximum (33,355 cells/mL) in early July (Fig. 24b). A
secondary maximum in abundance (19,663 cells/mL) was observed in August,
-------
53
due to pIcoplankton. A secondary peak was not observed in the biovolume
seasonal distribution (Fig. 24a) because of the low biovolume of the
picop Iankton. Samples were not taken during the late summer and early
fall. Abundance was low in November and decreased into early December
(11,388 cells/ml). Abundance increased slightly in January but returned
to December levels in February. Abundances in the early spring, fall and
winter were not significantly different. Also, biovolume was not
significantly different between the early spring, fall, winter and August
(Fig. 24a).
Considering biovolume, the BaciIlariophyta were dominant throughout
the study period accounting for as much as 12% but never less than 44? of
the phytoplankton biovolume (Fig. 25). The large drop in the relative
importance of diatoms in August of 1983 (to -30? of the total biovolume,
Makarewicz 1987) was not observed in 1984. A drop to 47? of the biovolume
did occur in August. The occurrence of a bloom of Rhizosolenia erJens is
in August of 1984, not observed in 1983, was the major cause of the
dominance of the diatoms during the summer (Table 25). With the decrease
in the relative biovolume of diatoms, a seasonal succession of Pyrrhophyta
peaking in July, Cryptophyta in early August, and Chrysophyta in August is
evident. Diatoms regained their spring predominant position by February
(Fig. 25). Cryptophyta appeared to increase in importance during the
study period accounting for 18? of the total biovolume in the late autumn
and winter samples.
Geographical Abundance and Distribution of Major Algal Groups
In 1983 the mean phytoplankton abundance for the sampling period
generally decreased from north to south to -Station 15, where abundance
increased and then decreased slightly southward (Fig. 26) (Makarewicz
-------
54 .
1987). In 1983 Aster ione! I a. formosa, Cycloteila comensis, £. comta, and
£. oceI Iata all had a higher biomass at Station 61 than at other stations
(Makarewicz 1987). A similar algal geographical distribution was not
observed during the 1984-85 sampling period (Fig. 27). There was no
obvious pattern on a cruise basis either (Fig. 28). Not one common algal
species had an abundance maximum at the northern stations in 1984.
Although not likely, this difference may be attributed to the sampling
patterns between 1983 and 1984. !n 1983 six of the seven cruises sampled
the same stations, while in 1984 only 50% of the cruises sampled the same
stations (Table 4). This sampling pattern apparently did not affect
zooplankton data. Similar to 1983, zooplankton populations were higher at
Station 61 in 1984.
Regional and Seasonal Trends in the Abundance of Common Taxa
Common species (Table 26) were arbitrarily defined as those
possessing a relative abundance of >0.1$ of the total cells or >0.5$ of
the total biovolume. Ninety-four percent of the common species observed
in 1984 were also common species in 1983. Ten percent of the common
species observed in 1983 were not common in 1984 (Table 27) (Makarewicz
1987).
The causes of these differences are difficult to evaluate. Natural
annual variability of plankton populations in the lake has never been
evaluated and cannot be evaluated until a more extensive data set exists.
Seasonal sampling variability exists between 1983 and 1984 and is the most
probable cause for the species differences observed. For example, both
Osc iI Iator i a m i n i ma and Stephanodiscus minutus were common in 1984 because
of their high density in the winter of 1984-85. Winter samples were not
available in 1983-84.
-------
55
Because of the similarity of the 1984 common species list to the 1983
list, a species by species description of autecology and regional and
seasonal trends are not warranted here and can be referred to in
Makarewicz (1987). Only new common species are discussed below.
BaciIlariophyta
Cyclotella stelIigera (Cl. and Grun.) V.H.
This species is a common offshore dominant in Great Lakes
phytoplankton assemblages (Stoermer and Kreis 1980). It is apparently
intolerant of highly eutrophic conditions in the natural environment
(Stoermer and Kreis 1980). In 1971 Munawar and Munawar (1982) reported C.
ste]Iigera to be a common lakewide species (>5% of the phytoplankton
biomass). In southern Lake Huron during 1974, mean abundance was 54
cells/mL with a maximum of 720 cells/mL in July (Stoermer and Kreis 1980).
At a single offshore station in southern Lake Huron, Lin and Schelske
(1978) observed a maximum of 762 cells/mL in late July with an average for
the sampling period (March-December 1975) of 111 cells/mL. Offshore
average abundance and maximum abundance in 1980 were 10.9 cells/mL and
60.7 cells/mL, respectively (GLNPO Data Base). Abundance in 1983 was only
6.5 cells/mL (Makarewicz 1987), while in 1984 average abundance was 25.3
cells/mL with a maximum of 267 cells/mL. The lower mean abundance
observed in 1983 and 1984 is probably caused by the lack of sampling in
the month of July in both years, when this species is historically
dominant. Abundance was low during the spring, fall and winter of 1984
(Fig. 29a). The population did increase by the 5-7 July sampling date
(mean station abundance = 123 cells/mL) but did not reach the higher
abundances historically observed later in July.
-------
56
Stephanpd|scu5 alpinus Hust. (= £. astrea var minutul us)
Munawar and Munawar (1979) did not list this species as common in
1971. Similarly, abundance was generally low in 1974 (mean = 2.6
cells/ml) (Stoermer and Kreis 1980), in 1975 (Lin and Schelske 1978), in
1980 (mean = 0.1 cells/ml) (GLNPO DataBase) and in 1983 (mean = 0.25
cells/ml) (Makarewicz 1987). Abundance was also low in 1984 (mean = 1.5
cells/ml), but biovolume represented 0.91$ of the total biovolume, thereby
qualifying it as a common species (Table 26). In 1984 seasonal abundance
peaked in early July (Fig. 29b) and was low (< 2 cells/ml) during the
remainder of the samp I ing period.
This species is a common minor element of the Lake Huron
phytoplankton assemblage. It appears to be favored by low levels of
eutrophication, but it is not tolerant of extreme levels of perturbation
(Stoermer and Kreis 1980).
Stephanodiscus^ mJnutus Grun. (= .S_. miputul us)
.S. minutus is generally considered to be a fall or winter blooming
species in mesotrophic or eutrophic lakes (Stoermer and Ladewski 1976).
It was not common in 1971 (Munawar and Munawar 1979) and possessed a low
abundance in 1974 (mean = 7.5 cells/mL) (Stoermer and Kreis 1980), in 1975
(mean = 4.2 cells/mL) (Lin and Schelske 1978), in 1980 (mean = 4.2
cells/mL) (GLNPO Data Base) and in 1983 (mean = 2.56 cells/mL) (Makarewicz
1987).
In 1984, average density was 19.4 cells/mL with a maximum density of
84 cells/mL. Seasonal abundance was low during the summer (< 6 cells/mL),
was higher during spring and autumn (-25 cells/mL) and peaked at 63
cells/mL in February of 1985 (Fig. 29c). This species is a winter
-------
55
Because of the similarity of the 1984 common species list to the 1983
I ist, a species by species description of autecology and regional and
seasonal trends are not warranted here and can be referred to in
Makarewicz (1987). Only new common species are discussed below.
BaciIlariophyta
Cyclotella stelIigera (Cl. and Grun.) V.H.
This species is a common offshore dominant in Great Lakes
phytoplankton assemblages (Stoermer and Kreis 1980). It is apparently
intolerant of highly eutrophic conditions in the natural environment
(Stoermer and Kreis 1980). In 1971 Munawar and Munawar (1982) reported C.
stelIigera to be a common lakewide species (>5% of the phytoplankton
biomass). In southern Lake Huron during 1974, mean abundance was 54
cells/mL with a maximum of 720 cells/mL in July (Stoermer and Kreis 1980).
At a single offshore station in southern Lake Huron, Lin and Schelske
(1978) observed a maximum of 762 cells/mL in late July with an average for
the sampling period (March-December 1975) of 111 cells/mL. Offshore
average abundance and maximum abundance in 1980 were 10.9 cells/mL and
60.7 cells/mL, respectively (GLNPO Data Base). Abundance in 1983 was only
6.5 cells/mL (Makarewicz 1987), while in 1984 average abundance was 25.3
cells/mL with a maximum of 267 cells/mL. The lower mean abundance
observed in 1983 and 1984 is probably caused by the lack of sampling in
the month of July in both years, when this species is historically
dominant. Abundance was low during the spring, fall and winter of 1984
(Fig. 29a). The population did increase by the 5-7 July sampling date
(mean station abundance = 123 cells/mL) but did not reach the higher
abundances historically observed later In July.
-------
56
Stephanod!sous alpinus Must. (= .S. astrea var minutulus)
Munawar and Munawar (1979) did not list this species as common in
1971. Similarly, abundance was generally low in 1974 (mean = 2.6
cells/ml) (Stoermer and Kreis 1980), in 1975 (Lin and Schelske 1978), in
1980 (mean = 0.1 cells/ml) (GLNPO DataBase) and in 1983 (mean = 0.25
cells/ml) (Makarewicz 1987). Abundance was also low in 1984 (mean = 1.5
cells/mL), but biovolume represented 0.91$ of the total biovolume, thereby
qualifying it as a common species (Table 26). In 1984 seasonal abundance
peaked in early July (Fig. 29b) and was low (< 2 cells/mL) during the
remainder of the sampling period.
This species is a common minor element of the Lake Huron
phytoplankton assemblage. It appears to be favored by low levels of
eutrophication, but it is not tolerant of extreme levels of perturbation
(Stoermer and Kreis 1980).
Stephanodlscus minutus Grun. (= 2.. mjnutul us)
£. mi putus is generally considered to be a fa I I or winter blooming
species in mesotrophic or eutrophic lakes (Stoermer and Ladewski 1976).
It was not common in 1971 (Munawar and Munawar 1979) and possessed a low
abundance in 1974 (mean = 7.5 cells/mL) (Stoermer and Kreis 1980), in 1975
(mean = 4.2 cells/mL) (Lin and Schelske 1978), in 1980 (mean = 4.2
cells/mL) (GLNPO Data Base) and in 1983 (mean = 2.56 cells/mL) (Makarewicz
1987).
In 1984, average density was 19.4 cells/mL with a maximum density of
84 cells/mL. Seasonal abundance was low during the summer (< 6 cells/mL),
was higher during spring and autumn (-25 cells/mL) and peaked at 63
cells/mL in February of 1985 (Fig. 29c). This species is a winter
-------
57
species. The low abundances historically observed are related to the lack
of w inter samp I ing.
Chlorophyta
Cosmarium sp.
Abundance of Cosmarium was low in 1971 (Munawar and Munawar 1979),
1974 (Stoermer and Kreis 1980), 1975 (Lin and Schelske 1978), 1980 (GLNPO
DataBase), 1983 (Makarewicz 1987) and even in 1984 (this study). Because
of its relatively high individual biovolume, it qualifies as a common
taxon (Table 26). Abundance peaks were evident in early July and early
winter (Fig. 29d).
Cryptophyta
Cryptomonas rostratiform is Skuja
Mean abundance of this species was low (0.8 cells/mL). However, the
high biovolume of the individual cell causes it to be a common species in
1984. £. rostratJlormJs apparently was not observed by Munawar and
Munawar (1979), Stoermer and Kreis (1980) or Lin and Schelske (1978) in
Lake Huron. In 1983 abundance was low (mean = 0.35 cells/mL). A maximum
of 8 cells/mL was observed with a mean of 0.8 cells/ml in 1984 (Table 26).
Seasonal abundance showed a great deal of variability, perhaps because of
the low abundance.
Cyanophyta
OsciI Iatori a m i n i ma G i ckIh.
Many of the previous workers (Munawar and Munawar 1979, Stoermer and
Kreis 1980, Lin and Schelske 1978) on Lake Huron did not identify all
fopms of Osc iI Iator i a to the species level. Average abundance in 1983 and
1984 was 2.9 (Makarewicz 1987) and 17.3 cells/mL, respectively. Maximum
-------
58 .
abundance was 335 cells/mL at Station 45 on 3 August 1984. Seasonal
abundance was bimodal with a maxima in mid-summer and winter (Fig. 30).
Vertical Distribution
On 15 August 1984, a series of vertical phytoplankton samples were
taken at two stations (Stations 15 and 37). The abundance increase with
depth at Station 37 can be primarily attributed to an increase in
picopIankton (Fig. 31). In general, non-pi cop Iankton abundance did not
increase with depth with the exception of Cyclotel l_g peel I ata. and £.
kuetzingiana var. planetophora (Fig. 31). There was no correlation
between the abundance increase and temperature (Fig. 31).
At Station 15, phytoplankton samples were taken to a depth of 30m
compared to 20m at Station 37. An increase in picoplankton, as well as
BaciI Iariophyta and Chrysophyta, was evident. The abundance increase in
these groups correlated with the decrease in temperature associated with
the metal imn ion (Fig. 32), Cyclotel I a comensis, £. ocel I ata and
Tabellaria flocculosa were responsible for the diatom abundance increases,
while Dinobryon sociale and Q, divergent were the primary causes for the
Chrysophyta increase with depth (Fig. 32). A similar vertical
distribution pattern was observed in Lake Michigan in 1984 (This Study).
Brooks and Torke (1977), Mortonson (1977) and Bartone and Schelske (1982)
have reported sub-surface maximum in the Great Lakes. Reasons for the
existence of the layer are not clear and are apparently complex,
encompassing physical, chemical and biological factors (Bartone and
Schelske 1982).
-------
59
Winter Cruises
Biomass and abundance were low during the winter and not
significantly different from the autumn and spring values (Fig. 24). As
during the non-winter season, the BaciI Iariophyta (58.2$ of the total
biovolume) was the dominant division. However, the Chrysophyta, which
were second in importance during the entire sampling period (9.5% of the
total biovolume), represented only 0.46$ of the total biovolume during the
winter. Similar to the Lake Michigan winter assemblage, the importance of
the Cryptophyta increased by a factor of greater than three from the
non-winter (5.7$ - 7.1$ for the entire sampling period) to the winter
period (17.8$).
FragiI aria crotonensis (mean = 65.4 cells/ml) and Stephanodiscus
minutus (mean =54.1 cells/mL) were the dominant diatoms during the winter
period. Abundance of .S_. minutus was high only during periods of cooler
water temperatures (Fig. 29c). Because of the high winter abundance, it
became a common species for the year (Table 26). Similarly, Fragi iaria
intermedia var. fall ax, Cryptomonas pyrenoidi fera and OsciIIator ia mini ma
became common species for the year (Table 26) by virtue of their higher
abundance or secondary maxima (Fig. 30) during the winter.
Other major winter diatoms, Cyclotella comensis and TabelIaria
fenestrata were common species (Table 26) during the non-winter period.
Common winter, as well as non-winter, species of Cryptophyta and
Cyanophyta were Gomphosphaeria Iacustris, Rhodomonas minuta var.
nannoplanktica (1.19$ of the total cells-winter) and Cryptomonas erosa
(5.30$ of total biovoIume-winter).
-------
60
Historical Changes in Species Composition
The literature pertaining to phytoplankton of the offshore waters of
Lake Huron is sparse. Fenwick (1962, 1968) published some qualitative
data, and Parkos et al. (1969) listed species observed. Quantitative data
from a single offshore station in 1971 exists (Munawar and Munawar 1982,
Vollenweider et al. 1974) and preliminary data covering 21 stations in
1971 are partially analyzed (Munawar and Munawar 1979). Stoermer and
Kreis (1980) reported on an extensive sampling program in southern Lake
Huron including Saginaw Bay during 1974 and provided an extensive
bibliography on Huron algal research. Lin and Schelske (1978) reported on
a single offshore station sampled in 1975. An intensive study of the
entire lake basin was performed in 1980 (Stevenson 1985), but only a few
offshore stations were sampled.
Since 1971 diatoms have been the dominant division. Dominant diatoms
in 1971 included species of Asterione I I a formesaf A- grac?I Iimaf
CyclotelI a comtaf £. glomerata, £. ocelI ata, £. mich iganiana, Melosira
island ica and M* granulata. In addition, species such as FragiI aria
crotonensis and Tabellaria fenestrata were common, while cryptomonads,
such as Rhodomonas tninuta and Cryptomonas erosa, contributed very heavily
during different seasons.
The following similar common diatoms (>0.1$ of the total cells) wlere
observed in 1974, 1983 and 1984: Asterionella formosa, Cyclotella
comensi sf £. mich igan iana, Q. ocelIataf Fragi i aria crotonensis, TabeI Iar i a
fenestrata, J. flocculosa var. i inearis and Rh izosolen ia sp. Synedra
fiI?form is was present in 1983 and 1984 but was not as common as in the
1974 southern Lake Huron plus Saginaw Bay data. The lower abundance of £.
stelIigera in 1983 (Makarewicz 1987) and 1984 compared to 1971 (Munawar
-------
61
and Munawar 1979), 1974 (Stoermer and Kreis 1980) and 1975 (Lin and
Schelske 1978) was caused by the lack of sampling during mid and late July
when this species is dominant.
Both Cryptomonas erosa and Rhodomonas minuta var. nannoplanktica were
dominant in 1971, 1974, 1983 and 1984. Numerically dominant chrysophytes
in 1971 were Dinobryon divergens and ChrysosphaerelI a longisp ina. In 1983
and 1984, these two species were common along with Q. cylindricum and J2.
sociaIe var. americanum (Table 26). Haptophytes were also numerically
abundant. In general, the diatom Synedra fiIiformis decreased in
abundance after 1974, while J3. cylindricum and D. sociale var. americanum
have increased in abundance. In general, species composition of common
offshore algae has changed little since 1971.
P i cop i ankton
4
Picoplankton abundance in 1984 (mean = 14,396; maximum of 3.5 x 10
cells/ml) was not dissimilar from 1983 (mean = 19.343; maximum of 6.3 x
10 cells/mL). On a numerical basis, the picoplankton represented 83.9$
of the total cells in 1984 but because of their small biomass, only 1.6$
of the total biovolume. Their relative numerical dominance in 1984 was
comparable to 1983 (86.6$). Prior to the 1983 study (Makarewicz 1987),
other researchers have not routinely reported on this group of organisms.
Indicator Species
Dominant diatoms in Lake Huron in 1983 and 1984 were Rhizosolenia sp.
(£. erJens is in 1984), TabelI aria flocculosa (biomass) and Cyclotella
comensis (numerically). Four species of CyclotelI a (£. comensis, C.
cpmta, £. kuetz i ngiana var. pignetophora and £. ocelI ata) represented 9.4$
of the total biomass in 1983 (Makarewicz 1987). In 1984 the same four
-------
62
species plus Cyclotella stelIFgerg accounted for 6.63$ of the total
biomass (Table 26). £. eriens is is often grouped with oligotrophic
offshore dominants even though it may occur in greater abundance in areas
receiving some degree of nutrient enrichment (Stoermer and Yang 1970).
Except for £. comensisr whose ecological affinities are poorly understood
(Stoermer and Kreis 1980), these species are associated with oligotrophic
or mesotrophic conditions. Tabellaria flocculosa is commonly associated
with mesotrophic conditions (Tarapchak and Stoermer 1976).
Dominant chrysophytes included Dinobryojl sociale var. americanum, J2.
divergens and I), cy I indr icum,. which are often associated with several
small members of the genus Cyclotella (Schelske et al. 1972, 1974)
included in the classical oligotrophic diatom plankton association of
Hutchinson (1967). Dominant cryptophytes, cyanophytes and dinofIagellates
were Rhodomonas minuta var. nannoplanktica, Cryptomonas erosaf
picoplankton and Ceratium hirundinelI a.
Because of the Iimited number of studies of the Lake Huron offshore
phytoplankton assemblage, there was also a limited basis for evaluating
the long-term effects of eutrophication. The ratio of mesotrophic to
eutrophic species in Lake Huron has not changed since 1971 (Table 28).
This suggests that the trophic status of the lake has not changed. Because
the trophic ratio has not been extensively used, interpretations of the
trophic ratio have to be carefully considered. For example, the lack of
change in the ratio in Lake Huron may simply represent a lack of
sensitivity in the ratio. However, interpretations using the trophic ratio
in collaboration with other indicators suggest interpretations of the
trophic ratio parallel the other indicators.
-------
63 .
Those studies available (Munawar and Munawar 1979, Nicholls et at.
1977a, Schelske et al. 1972, 1974) indicate that the waters of northern
Lake Huron generally contain phytoplankton assemblages indicative of
oligotrophic conditions. The designation of the offshore waters of
southern Lake Huron as oligotrophic based on phytoplankton composition in
1983 and 1984 is not unlike the trophic status suggested by Stoermer and
Kreis (1980) for the offshore waters of southern Lake Huron in 1974. This
agrees well with the trophic status as determined by the biomass
classification scheme of Munawar and Munawar (1982). With a mean biomass
of 0.38 g/m and 0.42 g/m for 1983 and 1984, respectively, Lake Huron
would be classified as oligotrophic.
Historical Chajigeg.in Community Abundance and Biomass
Some quantitative phytopIankton data exist for the offshore waters of
Lake Huron from at least 1971. The collections of Stoermer and Kreis
(1980) were from 44 stations in southern Lake Huron and Saginaw Bay. Lin
and Schelske (1978) collected from one offshore station in 1975. In both
studies, phytoplankton were concentrated on millipore filters rather than
by the settling chamber procedure used in the 1980 (GLNPO Data Base), 1983
(Makarewicz 1987) and 1984 studies. Thus, data sets are not strictly
comparable.
Munawar and Munawar (1982) collected with a 20-m integrating sampler
from April to December of 1971. Because Utermb'hl's (1958) procedure for
enumeration of algae was employed, these data were directly comparable to
the 1980, 1983 and 1984 data sets. Unfortunately, biomass data for only
one offshore station of Lake Huron was available for 1971 (Munawar and
Munawar 1979). Phytoplankton biomass between 1971, 1980, 1983 and 1984
was not significantly different (Fig. 33). The consistency of the
-------
64
mesotrophic-eutrophic ratio through time and the occurrence of
oligotrophic and mesotrophic indicator species suggest little change in
the trophic status of the offshore waters of Lake Huron.
-------
65
LAKE HURON
ZoopIankton
Annual Abundance of Zpoplankton Groups
Species lists (Table A10) and summary tables of abundance (Table A11)
and biomass (Table A12) are in Volume 2 - Data Report. The zooplankton
assemblage of 1984 comprised 53 species representing 31 genera from the
Amphipoda, Calanoida, Cladocera, Cyclopoida and Rotifera. The diversity
of species was similar to 1983 (58 species, 33 genera).
The Rotifera possessed the largest number of species (31) and
relative abundance (56.0$) followed by the Calanoida and Cyclopoida. The
Copepoda nauplii accounted for 18.6/5 of the total zooplankton abundance
(Table 29). The Calanoida (42.0$) followed by the Cladocera (27.5$)
contributed the most biomass to the zooplankton community. Rotifera
represented only 2.5$ of the zooplankton biomass. Average density and
biomass were 55,369+7,176 (mean±S.E.) organisms/m (46,230 - 1983) and
27.3+2.3 (mean±S.E.) mg/m (Table 6).
Seasonal Abundance and Distribution of Major Zooplankton Groups
Seasonally, the abundance and biomass were essentially identical
(Fig. 34) with a maximum in August. This pattern was similar to that of
Lake Michigan in 1984 (Fig. 16). A comparison to 1983 was not possible
because of the lack of samples in the spring and summer (Makarewicz 1987).
Except for the naupl ius stage of the Copepoda, abundance of the major
zooplankton groups was highest in August as compared to the spring and
late autumn samples (Fig. 35). Nauplii abundance was high throughout the
year with a general trend of decreasing abundance towards the winter. A
similar pattern was observed with biomass distribution with the exception
of the Calanoida. Calanoid biomass did not decrease markedly in the late
-------
66
fall as compared to other groups (Fig. 36). Growth of the individual
Calanoids, even with a decreasing abundance, kept Calanoida biomass high.
Common Species
Common Crustacea species (Table 30) were arbitrarily defined as those
possessing a relative abundance of >0.1$ of the total zooplankton
abundance or 1.0$ of the total biomass. Rot ifera species were considered
common if they accounted for >\,0% of the total zooplankton abundance or
biomass. The number of common species were identical in 1983 (22)
(Makarewicz 1987) and 1984 (22). Some differences in common species
composition were evident. Polyarthra remataf Notholea squamula, and
Leptodora k indti i were common in 1984 but not in 1983. Even though the
cladoceran Leptodora kindtii was not abundant in 1984, it was a common
species because of its high biomass per organism. In 1983 biomass was not
evaluated in the designation of common species. Daphnia retrocurva, Q.
schodleri and D. catawba were common in 1983 but not in 1984. D. catawba
was observed only in long hauls in 1983, while D. schodleri was not
observed at alI in 1984.
Changes in Species Composition
Crustacea
Crustacean studies of the offshore waters of the Lake Huron basin are
few in number. Patalas (1972) sampled 51 stations including Saginaw Bay
in August of 1968 with a 77-um mesh net. In 1971 eleven stations on a
transect from the Straits of Mackinac to the origin of the St. Clair River
were sampled from May to November with a 64-um net (Watson and Carpenter
1974). A 64-um mesh net was used to sample ~18 stations on eight dates
from April to October of 1974 in southern Lake Huron including Saginaw Bay
-------
67
(McNaught et al. 1980a). The 1980 study of Evans (1983, 1986) included
stations mostly from the nearshore rather than the offshore. The 1983
sampling cruises included 10 stations sampled (64-um mesh net) for each of
the three sampl ing dates between August and September. In 1984 eight
stations on five cruises (64-um mesh net) from May-December 1984 were
sampled.
In August of 1968, calanoids were dominated by Diaptomus siciI is, D.
ash I and i and D. minutus (Patalas 1972). These same three species were
predominant in 1971, 1974/75, 1983 and 1984 with the addition of D i aptomu s
oregonensis in 1983 and 1984 (Table 31). Abundance of Diaptomus .ash I.and I
and Diaptomus siciI is appears to have increased since 1971 (Table 31).
The 1974 D. minutus abundance was higher than either the 1971, 1983 and
1984 samples. However, the 1971, 1983 and 1984 data were only from
offshore sites, while 1974 data included samples from the eutrophic waters
of Saginaw Bay. The ol igotrophic indicator species, L imnocaI anus
macrurus, appears to be decreasing in abundance (Table 31).
In 1971, 1974/75 and 1983, the dominant cyclopoid was Cyclops
bicuspidatus thomasi (Table 31). Tropocyclops prasinus mexicanus increased
in abundance from 1971 to 1983. However, a notable decline occurred from
1983 (577/m ) to 1984 (21/m3), which may be related to the differences in
the timing of the fall sampling in these two years. Mesocyclops edax
appears to have increased in abundance (Table 31) from 1971 to 1983.
Abundance was lower in 1984 than in 1983. Cyclops vernal is,, often
associated with eutrophic conditions in Lake Erie, was higher in abundance
in the 1974 data. This higher abundance may again have been due to the
inclusion of the eutrophic of Saginaw Bay stations in the 1974 data set.
-------
63
Dominant cladoceran species in August of 1968 were Rosming
longirostris and Ho I oped i urn gibberum. Similarly, H. gibberinri, fi.
longirostris and Eubosmina coregonj were dominant in the August-October
period in 1974. Comparison of the 1971 and 1984 August data suggests
decreases in abundance of B. longirostris and iJ. gibberum.
Quantitative data on species of daphnids were not available for 1971,
but Daphnia retrocurva, Daphnia galeatg mendotag and J). longiremis were
commonly found in Lake Huron (Watson and Carpenter 1974). The dominant
daphnid species in 1983 and 1984 was JD. gal eata mendotae.
Evans (1985) recently reported that Daphnia pul icaria was a new
species dominating the Lake Michigan zooplankton assemblage. In 1983 in
Lake Huron, D. pul icaria was observed to be the third most important
cladoceran, while in 1984 it dropped to fifth in rank abundance (Table
30). Mean station abundance increased from north to south with a mean
density of 431 organisms/m for stations south of Saginaw Bay in 1983. In
1984, abundance never reached the levels of 1983 (Fig. 37).
J2. catawba was first reported in waters of Lake Huron in 1983
(Makarewicz 1987). This species was not considered to be either a common
or a less common species of the Great Lakes (Balcer et al. 1984). It
appeared exclusively in the long hauls from Lake Huron in 1983. A maximum
abundance of 1,610 organisms/m was observed in August at Station 12. It
was not observed in 1984.
Bythotrephes cederstromii was observed in Lake Huron for the first
time in the long haul of 1984. This European invader was first observed
in the Great Lakes in Lake Ontario in 1985 (Lange and Cap 1986). It is a
conspicuous species in the plankton of European oligotrophic lakes.
-------
69
Rot i fera
Stemberger et al. (1979) collected rotifers with a Nisken bottle at
5-m intervals to 20m followed by 10-m intervals to the bottom of the lake
at a number of offshore and nearshore areas. Samples were pooled and
filtered through a 54-um mesh net on the vessel. The greatest abundance
of rotifers in Lake Huron in 1974 occurred in late spring and early summer
(Stemberger et al. 1979), a period in which no samples were taken in 1983
and 1984. Comparison of the August-October samples suggested the
following between the 1974, 1983 and 1984 data sets; abundant rotifer
species in both studies were Conoch?I us un icornisf Polyarthrg vulgari sf
KeratelI a cochlearis and Ke11i cott i a longispina; £. unicornis was the
dominant rotifer in 1983; and KeratelI a cochlearis was dominant in 1974
(Table 30).
Evans' (1986) study of mostly nearshore areas suggests a difference
in dominant rotifer species between the offshore and nearshore waters.
Dominant rotifer species in this study included in descending rank:
Keratel I a cochlearis,. Ke I I i cott i a longisp inaf Synchaeta sp. and Conoch i 1 us
unicornis. Polyarthra vulgaris and ConochiI us unicorn is, which were
dominant in the offshore waters in 1974, 1983 and 1984, were less abundant
in the nearshore waters.
These differences in horizontal distribution of zooplankton are
expected in Lake Huron and are affected by the physical Iimnology of the
lake (McNaught et al. 1980a). For example in the warmer inshore areas,
cladocerans grow best, while calanoids tend to be found in offshore waters
(McNaught et al. 1980a). Nearshore waters are also influenced by the
movement of the zoopIankton-rich eutrophic waters of Saginaw Bay into the
nearshore zone south of the Bay. In general, inshore zooplankton
-------
70
densities are greater than offshore densities (McNaught et al. 1980a).
Similarly, abundance and species composition of rotifers increase and
differ in the shallow more productive waters of the western basin of Lake
Erie (Fig. 62).
Geographical Abundance and Distribution of Zooplankton Groups
The mean station zooplankton abundance was higher in the northern
half than in the southern half of Lake Huron (Fig. 38) due primarily to
higher rotifer abundance in the north. A similar pattern was observed in
1983 (Makarewicz 1987). With a biomass comparison, no obvious difference
between the northern and southern half of the lake was evident (Fig. 39).
Cyclopoida and Cladocera abundance was relatively similar along the
north-south axis. The Calanoida and naupl ius stage of the Copepoda had a
geographical distribution pattern similar to the Rotifera with increasing
abundance from Station 61 to 45, descending abundance from Station 45 to
27 and 12, and increasing abundance southward (Fig. 39). McNaught et al.
(1980a) observed abundance increases of the cyclopoid copepodites, £.
bicusp idatus and J. praslnus, north to south in southern Lake Huron. In
1983 rotifers also decreased in abundance from north to south to Stations
9 and 6 where a si ight increase was evident.
The 1983 and 1984 data (Figs. 37 and 39) suggest a trend of
increasing total zooplankton abundance from Station 12 northward with the
exception of Station 32 in 1983. Station 32, located northeast of the
mouth of Saginaw Bay, would appear to be too far offshore to be influenced
by the higher abundances in the Bay. However, Stoermer and Kreis (1980)
have observed mid lake stations in southern Lake Huron to be affected by
populations of phytoplankton from Saginaw Bay in 1974. Although the
transport of eutrophication-tolerant algal populations into Lake Huron
-------
71
from Saginaw Bay has been mitigated in recent years (Stoermer and Theriot
1985), the mechanism of transport still exists and thus the transport of
zooplankton could still take place from Saginaw Bay.
A number of zooplankton species possessed horizontal distributions
that varied along the north-south axis. These differed between 1983 and
1984. In 1983 Diaptomus minutus abundance was lower in the northern
portion of the lake, while Daphnia retrocurva had a maximum limited to the
far northern stations. Abundance of both ConochiI us unicprnis and
Ke111cott i a longisp ina decreased from north to south. Ho I opediurn gibberum
had a higher abundance north of Saginaw Bay, while Mesocyclops edax
abundances were higher south of Saginaw Bay. Cyclops bicuspidatus thomasi
was more abundant at the far northern stations than in the rest of the
lake (Makarewicz 1987).
In 1984 Diaptomus s i c iIi st the copepodite of Mesocyclops, Notholca
squ annulaf Polyarthra vulgaris and Synchaeta sp. had abundances that were
higher in southern Lake Huron (Fig. 41). Mesocyclops edgx adults did not
have a higher abundance in southern Lake Huron as in 1983 (Makarewicz
1987). However, juveniles of Mesocyclops were higher in the southern Lake
Huron (Fig. 41). Similar to 1983, abundances of Ho I opediurn gibberum,
KelIicottia longispina and ConochiJus unicorn is were higher in northern
Lake Huron (Table 32), while Diaptomus minutus was lower in the northern
half of the lake. A similar north-south distribution of algal populations
was not observed in 1984.
Indicators of Trophic Status
The calanoid/cyclopoid plus cladoceran ratio (the plankton ratio) has
been employed as a measure of trophic status in the Great Lakes (Gannon
and Stemberger 1978, McNaught et al. 1980a). Calanoid copepods generally
-------
72
appear best adapted for oligotrophic conditions, while cladocerans and
cyclopoid copepods are relatively more abundant in eutrophic waters.
Using this ratio, McNaught et al. (1980a) identified the offshore waters
of southern Lake Huron to have a higher quality water than the nearshore
waters. Because the 1983 and 1984 samples were all from the offshore, no
such comparison could be made. However, the 1984 plankton ratio was high
and variable from north to south (Table 33). A comparison of the 1983 and
1984 mean phytoplankton ratio suggests a lower quality of water at
Stations 6 and 9 and perhaps at Station 61. Water chemistry data suggests
these southern stations have higher chloride, sulfate, total phosphorus
and turbidity levels and lower silica levels than the rest of the lake
(Fig. 42).
Station 61 might be influenced by waters from Lake Michigan. The
plankton ratio at Station 61 in Lake Huron is comparable more to northern
Lake Michigan than the rest of Lake Huron (Table 34). The physical
transport of plankton populations by water currents from Lake Michigan
into Lake Huron through the Straits of Mackinac has been demonstrated
(Schelske et al. 1976).
Species considered to be indicators of eutrophic waters were rare
compared to the western basin of Lake Erie and restricted to extreme
southern Lake Huron (Station 6) (F iIinia long iseta [6.6/m H, Trichocerca
mill tier in Is p2.3/m 3) or not detected (Brachionus spp.). The rotifer
community in 1983 and 1984 was dominated by Polyarthra vulgar is, Keratella
cochlearis, Conoch iI us unicornis and KeI Ii cott i a long isp ina. This
association has been considered to be indicative of an oligotrophic lake
(Gannon and Stemberger 1978). The offshore abundances of Ho I opediurn
g ibberum, Conoch iI us unicorn is and Ke iIi cott i a long isp ina were greater
-------
73
north of Saginaw Bay than south of it (Table 32) suggesting better water
quality in northern Lake Huron. Ho I opediurn gibberum has been reported as
an indicator of oligotrophic lakes in Sweden (Pejler 1965) but was widely
distributed in both oligotrophic and eutrophic waters in the Laurentian
Great Lakes region (Gannon and Stemberger 1978),
The low zooplakton abundance, compared to those of Lakes Erie and
Michigan (Table 6), the presence of the oligotrophic rotifer association,
the domination of the calanoids, and the fairly abundant presence of the
oligotrophic Diaptomus sic?I is (McNaught et al. 1980a) suggest
ol. igotrophic offshore waters for Lake Huron in 1983 and 1984.
Historical Trends in Abundance
Offshore crustacean zooplankton data collected with similar mesh size
nets (64 urn) exist for Lake Huron. The 1970 study (Watson and Carpenter
1974; 88 collections) sampled the whole lake, while the 1974/75 work
(McNaught et al. 1980a; 46 collections) was from southern Lake Huron. A
comparison of the cruise averages for Crustacea (excluding nauplii) (Fig.
43) suggests an increase in abundance from 1970 to 1974 and 1983 followed
by an abundance drop in 1984. However, an ANOVA indicates that the means
are not significantly different. A similar conclusion of no change in
trophic status since 1970 was reached with phytoplankton abundance.
Stemberger et al. (1979) collected Rotifera samples from 44 stations
in southern Lake Huron in 1974. Samples were taken with a Nisken bottle
at 5-m intervals to 20 m and at 10-m Intervals below that. After
collection, samples were immediately pooled and filtered through a 54-um
net. In 1983 (Makarewicz 1987) and 1984, a vertical tow (64-um net) was
taken from 20 m to the surface. Both studies are not directly comparable
in that Stemberger's et al. (1979) work represented the entire water
-------
74
column, while the 1983 and 1984 studies were basically samples from the
epilimnion. The 1974 and 1984 sampling periods are not significantly
different. A comparison of mean station seasonal abundance suggests that
the spring and autumn abundance in 1983 and 1984 was lower than in 1974
(Fig.44). Also, abundance of major species was lower in 1983 and 1984
than in 1974 (Table 35) This difference in abundance is related to two
things: (1) Stemberger et al. (1979) used a smaller meshed net which
gives a more accurate quantitative sample and thus a higher abundance
(Likens and Gilbert 1970); and (2) two different segments of water are
being sampled and compared. For example, Makarewicz and Likens (1979)
demonstrated higher abundances and different species composition in the
hypollmnion as compared to the epilimnion of Mirror Lake, New Hampshire.
Trophic Interactions
Within the offshore, there appears to be few changes that could be
attributed to nutrient control. Phytoplankton biomass and zooplankton
abundance of the offshore waters of Lake Huron in 1971, 1980, 1983 and
1984 are not significantly different. In general, offshore species
composition of phytopiankton has changed little since the early 70's.
However, there has been a significant lake-wide change in species
composition of zooplankton. Prior to 1983, there are no records of
Daphnia pul icaria in Lake Huron. In 1983 and 1984, this species ranked
third and fifth in abundance in Lake Huron, respectively. The appearance
of the large JD. pul icaria is generally attributed to a release from
size-selective predation of forage fish in Lake Michigan (Scavia et al.
1986, This Study) and Lake Erie (This Study). Daphnia pulicaria abundance
is correlated with decreased phytoplankton abundance in 1984 (Table 36),
which suggests an additional grazing pressure on pytoplankton stocks in
-------
75
Lake Huron. This may lead to changes in phytoplankton abundance and
composition (See Discussion in Lake Michigan on Trophic Interactions).
A top-down effect on zooplankton is likely in Lake Huron. A careful
examination of the time trends in the forage fish base of Lake Huron
similar to what was done on Lake Erie (This Study) would provide further
insight on this hypothesis.
-------
76
LAKE ERIE
PhytopIankton
Species lists (Table A13) and summary tables of abundance (Table A14)
and biovolume (Table A15) are in Volume 2 - Data Report. A summary of
water chemistry paramters is presented in Table 6.
Annual Abundance of Major Algal Groups
The phytop Iankton assemblage of 1984 was comprised of 356 species
representing 104 genera (Table 37). Compared to 1983, a 4.3$ reduction in
the number of species and a 1.0$ increase in the number of genera were
observed. Seventy-five percent of the decrease in species number from
1983 to 1984 was due to a decrease in species of Chlorophyta. The total
number of species in 1983 (372) and 1984 (356) was considerably higher
than the 125 to 150 species observed in all basins in 1970 (Munawar and
Munawar 1976).
In 1984 the diatoms possessed the greatest number of species (171,
48$ of the total species) and biomass (47.8$ of the total) (Tables 37 and
38), while the second largest number of species (96) was observed for the
Chlorophyta (Table 37). A similar observation occurred in 1983
(Makarewicz 1987). These diversity observations represent significant
changes from 1970, when the Chlorophyta possessed the largest number of
species (78) and only 21 diatom species were observed (16.3$ of the
species) (Table 38). However, diatoms in 1970 still accounted for 53$ of
the biomass (Munawar and Munawar 1976).
Highest relative densities were attained by the picoplankton (89.6$)
in 1984. In 1983 the Chlorophyta had the second highest biomass, while in
1984 they were fourth, si ightly lower than the Pyrrhophyta and
Cryptophyta.
-------
77
Seasonal Abundance and Disbribution of Major Algal Group?
The average density and biomass for the sampling period were 45,080
cells/ml (40,055 cells/ml; 1983) and 1.00 g/m3 (1.36 g/m3; 1984).
Seasonally, abundance (cells/mL) peaked in mid-April at 88,762 cells/mL
(mean abundance station), decreased through May and July, and leveled off
during August. A fall/early winter secondary maximum at -40,000 cells/mL
was observed before a decline to 28,200 cells/mL in February of 1985 (Fig.
45a).
A different pattern emerged from the seasonal biovolume totals.
Similar to the seasonal abundance pattern, peak biomass occurred In April.
However, biovolume was low in July and steadily increased into September
(Fig. 45b) followed by a decrease from December into January and February.
Except for the lower biomass in 1983 and 1984, the timing of the spring
and autumn biomass peaks is similar to that observed in 1970 (Munawar and
Munawar 1976).
Diatoms were the dominant group throughout the year (47.8$ of the
total biovolume). However, seasonally their importance varied
considerably (Fig. 46) but in a pattern similar to 1983 (Makarewlcz 1987).
Diatoms were dominant in April and May (~6Q% of the biovolume) and were
succeeded by the Cryptophyta in July and the Chlorophyta in August. A
similar succession and relative importance were observed in 1983
(Makarewicz 1987) and In 1970 (Munawar and Munawar 1976). By December and
through the winter months, the diatoms were again dominant accounting for
as much as 78$ of the biovolume.
Geographical Abundance and Distribution of Major Algal Groups
Abundance for the sampling period varied geographically but was
similar to 1983 observations (Makarewicz 1987). Biomass generally
-------
78
decreased eastward. The western basfn (Stations 60, 57 and 55) possessed
3 3
a greater biomass (1.38 g/m , S.E.=.23) than the eastern basin (0.54 g/m ,
S.E.=.82) (Stations 18, 15 and 9) and the central basin (0.76 g/m3,
S.E.=.09) (Stations 42, 73, 37, 78 and 79) (Table 39). The considerably
greater abundance of the western basin was attributed to the picoplankton
(Fig. 47). However, the higher biomass of the western basin (Table 39)
was due to greater abundance and biomass of the BaciIlariophyta,
Cyanophyta, Chlorophyta, Cryptophyta and Chlorophyta in the western basfn.
The increase in the total abundance, but not in biomass (Table 39), east
of Station 78 was attributed to the higher abundance of picoplankton (Fig.
47). Picoplankton contributed little to community biomass (~1.5$, Table
40) because of their extremely small size (0.5 to 2.0um).
As in 1983, the general pattern of higher abundance in the western
basin was observed on each sampling date except for perhaps the late fall
and early winter cruise (Fig. 48). It appeared that with cooling of the
lake in the autumn, abundance became similar throughout the lake (Fig.
48). In 1983 (Makarewicz 1987), at least 12 common species had higher
abundances in the western basin. Similarly in 1984, many of the same
species had geographical abundance patterns with maxima in the western or
central basin (Table 41) (Figs. 48 and 49). A difference in species
abundance from the various basins of Lake Erie has been documented
previously (Munawar and Munawar 1976, Davis 1969a).
Pi cop Iankton
Picoplankton abundance in 1984 (mean = 38,075 cells/mL; maximum of
c
3.8 x 10 cells/mL) was not dissimilar from 1983 (mean = 33,171 cells/ml;
c
maximum of 1.4 x 10 cells/mL). On a numerical basis, the picoplankton
represented 88.2$ of the total cells and 6,1$ of the total biomass.
-------
79 ,
Picoplankton relative numerical dominance in 1984 was similar to 1983
(84.5$ of total cells). Prior to the 1983 study (Makarewicz 1987), other
researchers have not routinely reported on this group of organisms.
Regional and Seasonal Trends in the Abundance of Common Species
Common species (Table 40) were arbitrarily defined as those
possessing a relative abundance of >0.1$ of the total cells or >0.5% of
the total biovolume. Eighty-four percent of the common species observed
in 1984 were also common species in 1983. Thirty percent of the common
species observed in 1983 were not common in 1984 (Table 41).
The causes of these differences is difficult to evaluate. Natural
annual variability of plankton populations in the lake has never been
evaluated and can not be evaluated until a longer data set exists.
Considerable seasonal sampling variability exists between 1983 and 1984
and is the most probable cause for the species differences observed. For
example, Coelastrum microporum was common in 1983 because of its high
density in October (Makarewicz 1987). October, September and November
samples were not taken in 1984-85.
Because of the similarity of the 1984 common species list to the 1983
list, a species by species description of autecology and regional and
seasonal trends are not warranted here and can be referred to in
Makarewicz (1987). Only new common species are discussed below.
BaciIlariophyta
Asterione I I a formosa Mass.
A common species in Lake Michigan and Lake Huron in 1983 and 1984
(Makarewicz 1987, This report), .&. formosa was a dominant species in Lake
Erie prior to 1950 (Verduin 1964). Hohn (1969) stated that A. formosa
-------
80
maintained constant densities between 1938 and 1965 but its relative
importance declined. Between 1967-1975, a decline in A- formosa was
evident from nearshore data (Nichols et al. 1977b). Munawar and Munawar
(1976), working with samples from the entire lake, observed that those
species, such as .A,, formosa, dominant before 1950 continued to be less
important in 1970. During February of 1976, .A. formosa comprised 10.3? of
the total biomass but contributed less than 5% of the total biomass on all
sampling dates in the western basfn (Gladish and Munawar 1980).
In 1975-76, h. formosa was a common species in the central basin in
early April (Reuter 1979). However, it was not a common species in 1983.
Average abundance and biomass in 1983 were only 8.7 cells/tnL and 2.6
mg/m , respectively. It was a dominant species in 1984 (Table 40).
Average abundance and biomass in 1984 were 73.4 cells/mL and 48
mg/m , respectively. Maximum abundance was 942 cells/mL at Station 42 on
1 May 1984. Seasonally, abundance was high in April and peaked by early
May (mean station abundance = 278 cells/mL). However, abundance was low
the rest of the year (Fig. 51a).
Melosira islandica 0. Mull.
Historically, M. is Iandica has not been a common species in Lake
Erie. Michalski (1968) noted it as sub-dominant during the vernal and
autumnal period from nearshore data In 1966-67. Similarly, Nicholls et
al. (1977b) believed it to be a spring species between 1967 and 1975. In
1970 M. islandica represented 27.5$ of the total biomass on the 21-26
October cruise of Lake Erie (Munawar and Munawar 1976). Giadish and
Munawar (1980) did not report this species as common in the western basin
in 1975-76; E. granuiata was common in 1975-76. Similarly In 1983, M.
-------
81
granulata was common (Makarewlcz 1987) while E. tslandica was not (mean
abundance = 2.9 cells/mL; mean biomass = 3.0 mg/m ).
In 1984 this mesotrophic indicator species (Tarapchak and Stoermer
1976) was the fourth most common diatom on a biomass basis (Table 40).
Average abundance was 31.5 cells/mL with a maximum of 1,564 ceils/mL at
Station 55 on 20 April 1984. Abundance peaked in April (mean station
abundance = 190 cells/mL) and was low the rest of the year (Fig. 51b).
Geographically, abundance was definitely higher in the western basin (Fig.
49). The high abundance of M, isiandica in the western basin of Lake Erie
is correlated with the spring bloom of this species in southern Lake
Huron.
Chlorophyta
Crucigenia rectangularts (Brawn) Gay
This species is usually a minor element of summer phytoplankton
assemblages of mesotrophic to eutrophic lakes (Stoermer and Ladewski
1976). Historically, this species has not been common in Lake Erie.
Abundance in 1983 (mean = 1.9 cells/mL) and 1984 (mean = 5.1 cells/mL)
was low . Because of its relatively large size, ft became a common
species accounting for 1.01? of the total biomass (Table 40). Seasonally,
abundance peaked in August (mean station abundance = 41.7 cells/mL) (Fig.
51d).
Cyanophyta
Anabaena sp.
Starting in 1958, Anabaena became more prevalent during the fall and
summer at least through 1963 (Davis 1969a). In 1966-67, short-lived
summer pulses of Anabaena were observed at a nearshore station by
-------
82
Michalski (1968). Munawar and Munawar (1976) observed populations of
Anabaen^ spiroides to be "weI I developed" in both the western and central
basins during the summer of 1970. During 1975-76, Cyanophyta biomass
never exceeded 20 mg/m . Aphan izomenon fIos-aquae was the most common
taxa encountered in 1975-76, wh ile Anabaepa sp. occurred less commonly in
the central basin (Reuter 1979). Although species are not mentioned, a
decrease in Cyanophyta biomass was observed at a nearshore site between
1967 and 1975 (Nichols et al. 1977b). Abundance in 1983 was low (mean
abundance = 15.1 cells/ml) (Makarewicz 1987).
In 1984 mean abundance was 47.8 cells/mL. The percent of total
biomass (0.87$) for Anabaena sp. was the same as Aphanizomenon flos-aquae
during the 1984 study (Table 40). Seasonally, abundance peaked at 255
cells/mL (mean station abundance) on 7 August 1984 (Fig. 51c). A maximum
abundance of 867 cells/mL was observed at Station 55 on 19 August 1984.
No obvious geographical pattern was observed.
Changes in Species Composition
Davis (1969a) has reviewed the extensive earlier work on Lake Erie,
while Munawar and Munawar (1982), Gladish and Munawar (1980) and Nicholls
(1981) discuss the more recent material. Verduin (1964) has concluded
that before 1950 the phytoplankton of western Lake Erie had been dominated
by Asterionella formosaf TabelI aria fenestrata and Melosira amb igua,
whereas fn 1960-61 the dominant forms had been fragilaria capucina,
Coscinodiscus radiatus (probably Actinocyclus normanii f. subsalsa) and
Melosira b inderana (=Stephanod tscus b inderanus).
As with Munawar and Munawar (1976), the 1983 study (Makarewicz 1987)
confirmed Verduin's (1964) observations that those species dominant before
1950 (.A., formosa, J. fenestrata and .M,. ambigua) continued to be less
-------
83
important in the 1983 collections. Act i nocycI us normanIi f. subsalsa
(=Coscinodi sous roth i i) and StephanodIscus binderanus were dominant Fn
1961-62 (Verduin 1964) and in 1970 (Munawar and Munawar 1976). FragiI aria
capucina was a dominant in 1961 but not in 1970. By 1983 Actinocyclus
normani i f. subsalsa was only the fifth most prevalent diatom, but on a
numerical basis FragiI aria capucina was the second most prevalent diatom
in the western basin and in the entire lake (Makarewicz, 1987). In 1984
Actinocyclus normanli f. subsalsa was not even a common species (Table
40).
Dominant species in 1983 and 1984 were Stephanodiscus nlagarae,
Fragi I aria crotonensis,, Cosmar i urn sp., Cryptomonas erosa, Rhodomonas
mJnu.ta var. nannopl ankt ica, Osci I latoria subbrevis, Osci I lator ia tenuis
and Qeratium h irupdinel I a (Table 40). Fragi laria capucina,, Coel astrum
mlcroporum, Osci I Iatoria subbrevis and Q. tentiIs were dominant in 1983
only (Makarewicz 1987), while Anabaena sp., Aphanizomenon flos-aquae and
AsterionelI a formosa were also dominant in 1984,
Aster?one!I a formosa has not been prevalent in Lake Erie since prior
to 1950. Verduin (1964) stated that before 1950 AsterionelI a formosa was
a dominant species in western Lake Erie. Similarly, Davis (1969a)
reported AsterionelI a as the dominant organism in the spring pulse of the
central basin prior to 1949. Numerous workers (Hohn 1969, Nichols et al.
1977b, Munawar and Munawar 1976, Gladish and Munawar 1980) reported a
decl ine in .A,, formosa after 1950. The low abundance of A- formosa was
apparent into 1983 (mean = 8.7 cells/mL, Makarewicz 1987).
Average density of A. formosa was 73.4 cells/mL in 1984 representing
5.6$ of the biomass (Table 40). Maximum density in March of 1938 was 96.6
cells/mL with a March mean of 553 cells/mL (Hohn 1969). No samples were
-------
84
taken in March of 1984, but the April average was 226 cells/ml (maximum
abundance = 942 cells/ml in May ). In 1984 during the three cruises in
April and May, Asterionella formosa was the dominant spring species on a
biomass basis and the second most important diatom on a numerical basis
(Table 43).
Although occurrences of common and dominant species in 1970, 1983 and
1984 were similar, dramatic decreases in abundance of these species were
evident (Table 44). This pattern was evident in all three basins.
Indicator Species
Munawar and Munawar (1982) concluded that the species of
phytoplankton found in 1970 usually occurred in mesotrophic and eutrophic
conditions. Common species in 1983 included eutrophic indicators
(FragiI aria capucina, Melosira granulata, Peridinium aciculiferum,
Pediastrum s i mp i exf Scenedesmus ecornis) and mesotrophic indicators
(Stephanodiscus niagarae, FragiI aria crotonensisf TabelI aria flocculosa)
(Makarewicz 1987). A similar set of major common species occurred in
1984, including the mesotrophic indicators Stephanodiscus n iagarae,
FragiI aria crotonensis and TabelI aria flocculosa and the eutrophic
indicators Fragi I aria capucina. Per id in ium actcul iferum and Pediastrum
simplex. The eutrophic indicators Melosira granulata and Scenedesmus
ecornisf common in 1983, were present in 1984 but were not common (>0.1$
of the total cells or >Q.5% of the total biovolume). Interestingly, a
mesotrophic indicator, Melosira island lea, not common in 1983, was common
in 1984 accounting for 4.1? of the total biomass (Table 40). However, the
abundance of M. islandica in western Lake Erie appears to be influenced by
the Lake Huron M, islandica population.
-------
85 .
Evidence of a shift in trophic status since 1970 is provided by a
comparison of distribution of dominant diatom indicator species in 1970,
1983 and 1984 (Table 45). The number of dominant eutrophic species has
decreased, while the number of dominant mesotrophic species has increased.
The mesotrophic-eutrophic ratio suggests a shift to mesotrophic conditions
for the western basin.
Historical Changes in Community Biomass
Between 1927 and 1964, a large and consistent increase in the total
abundance of phytoplankton of the central basin had occurred (Davis 1964,
1969a). Nichols et al. (1977b) observed that a decline in nearshore
phytoplankton of the western basin occurred between 1967 and 1975.
However, Gladish and Munawar (1980) discounted this finding and suggested
that no realistic conclusion could be drawn from a comparison of biomass
between 1970 and 1975.
The mean basin weighted biomass was 3.4, 1.49 and 0.8 g/m in 1970,
1983 and 1984, respectively. A 56 to 76$ reduction in algal biomass has
occurred in offshore waters of Lake Erie from 1970 to 1983/84. This
reduction in biomass is evident for all seasons of the year (Fig. 52).
The historically highly productive western basin (Munawar and Burns 1976)
has had a steady decrease in biomass from 1958 to 1984 (Fig. 53). Since
1975 chlorophyll concentrations have decreased in all basins (Fig. 54).
Phosphorus levels have also decreased in all sub-basins (Fig. 55),
Between 1970 and 1983-1984, dramatic reductions In maximum biomass of
common species have occurred (Table 44), For example, in the nuisance
species Aphapizomenpn f los-aquae,. a 96% reduction in the maximum biomass
observed has occurred since 1970. Stephanodiscus binderanusf a eutrophic
indicator species, has decreased in biomass by 90$ in the western basin.
-------
86
Similary, Frag!I aria capucina, another eutrophic indicator, has decreased
(99% reduction) dramatically within the phytopiankton community.
Based on maximum biomass concentrations (Vollenweider 1968), Munawar
and Munawar (1976) classified the western basin as highly eutrophic, the
eastern basin as mesotrophic and the central basin between the mesotrophic
and eutrophic conditions. Using the same classification system of
Vollenweider (1968):
Ultraol igotrophic <1 g/m ,
Mesotrophic 3 to 5,g/m
Highly eutrophic >10 g/m
the western basin (maximum biomass = 6.6 g/m , Station 55, April) in 1984
would be between mesotrophic and eutrophic, the central basin (maximum
biomass = 3.0 g/m , Station 37, August) would be mesotrophic and the
eastern basin (maximum biomass = 2.0 g/m , Station 15, April) would be
between oligotrophic and mesotrophic. Similarly, the classification
scheme of Munawar and Munawar (1982), based on mean phytopiankton biomass,
suggests an improvement in water quality between 1970 and 1983/84 (Table
46) in all basins of Lake Erie.
-------
LAKE ERIE
ZoopIankton
Annual Abundance of Zooplankton Groups
Species lists (Table A16) and summary tables of abundance (Table A17)
and biomass (Table A18) are in Volume 2 - Data Report. The zoopIankton
assemblage of 1984 comprised 81 species representing 39 genera from the
Amphipoda, Calanoida, Cladocera, Cyclopoida, Harpacticolda and the
Rot ifera. Compared to 1983 (37 genera, 66 species), an 18.5$ increase in
number of species was observed. This difference was mostly attributable
to an increase in number of rotifers (34 to 48).
The Rot ifera possessed the largest number of species (48) and
relative abundance (80.1?) followed by the Cyclopoida and Calanoida. The
nauplius stage of the Copepoda accounted for 10.4? of the total
zooplankton abundance (Table 47). On a biomass basis, the importance of
the Rot ifera dropped to 13.6$ of the zooplankton biomass because of their
small size, while the Cladocera contributed 40.5? of the biomass (Table
47). Average density and biomass for the study period were 159,615+34,000
organisms /m3 (mean±S.E.) (288,100/m3 - 1983) and 53.6±6.2 mg/m3 (Table
6).
Seasonal Abundance gnd Distribution of Major Zooplankton Groups
Seasonally, biomass distribution (Fig. 56a) was unimodal, peaking in
August. The seasonal abundance pattern suggested two peaks: one in spring
and a second in late summer (Fig. 56b), which were caused by peaks in
rotifer abundance. A sampling pattern that includes the June-July and
September-October period is needed to fully evaluate the seasonal
distribution patterns.
-------
88
The 1984 seasonal abundance pattern (Fig. 57) of the various
zooplankton groups was similar to 1983 (Makarewlcz 1987). Rotifera
abundance peaked in May and a secondary peak was noted in late August
(Fig. 57). Cladocera and Calanolda abundance was low in spring, peaked in
early August and decreased the rest of the year. Cyclopoida achieved
their highest abundance in late August (Fig. 57a). The biomass seasonal
distribution pattern of the major zooplankton groups generally mimicked
the abundance pattern (Fig. 58).
Geographical Abundance and Distribution of Zooplankton Groups
Geographically, zooplankton abundance was similar to 1983 (Makarewicz
1987), with abundance being higher in the western basin and decreasing
easterly to Station 79 (Fig. 59). Abundance increased slightly eastward
through the eastern basin (Stations 18, 15 and 9). The Rotifera were the
cause of the high zooplankton abundance in the western basin, although the
Copepoda nauplii also had a slightly higher abundance in the western basin
(Stations 60, 57, 55) (Fig. 59b).
Interestingly, biomass was similar in all three basins of Lake Erie
(Fig. 60a) even though Rotifera biomass was highest in the western basin,
particularly et the most western Station 60. The high rotifer biomass was
countered by a low Cladocera biomass at Station 60 (Fig. 60b), while at
the next easterly station (57), Rotifera biomass was low and Cladocera
biomass was high. A low Cladocera abundance was observed at Station 60 in
1983 (Makarewicz 1987). Perhaps there is an influence of the Detroit
River at this station that affects Cladocera abundance negatively and
Rotifera positively.
Except for Station 60, Cladocera abundance generally decreased
eastward into and through the central basin. In the eastern basin,
-------
89
Cladocera biomass (Fig. 60b), but not abundance (Fig. 59b), increased
easterly. Cyclopoida and Calanoida abundance was higher in the central
and eastern basin as compared to the western basin.
Common Species
Common Crustacea species (Table 48) were arbitrarily defined as those
possessing a relative abundance >0.1$ of the total abundance or 1.0$ of
the total biomass. Rot ifera species were considered common if they
accounted for >1.0$ of the total zooplankton abundance or biomass. The
number of common species in 1983 (25) and 1984 (27) was similar, but there
were changes in composition of the common species. Daphnia pulicaria,
common in 1984, was not observed in 1983 in Lake Erie. Leptodora kindti if
KeratelI a earlinae and Notho lea squamulaf common in 1984, were present in
1983 but not common. Common species observed in 1983, but not in 1984,
included Diaptomus sic!loldes, Diaphanosomg Ieuchtenbergianumf Colletheca
sp. and Ke11?cott i a longispina.
Changes in Species Composition
Crustacea
Brooks (1969) suggested that a shift in the Lake Erie cladoceran
assemblage was evident by 1948-49 with smaller cladocerans, such as
Daphn ja galeata mendotae. D. retrocurva and Diaphanosoma sp., being more
abundant than in 1938-39. In 1970 the most commonly found Daphnia species
were D. retrocurva, Q. galeata mendotae and D. longiremis (Watson and
Carpenter 1974)j Bosmina longirostris and Eubosmina coregoni were more
abundant (Watson and Carpenter 1974). Predominant cladoceran species in
1983 were small forms similar to those observed in 1970. In 1983 the
predominant Cladocera in descending order were Eubosmina coregon i f Daphnia
gaIeatq mendotae, Bosmina longirostris, Diaphanosoma Ieuchtenbergfanum and
-------
90
Chydorus sphaericus (Makarewicz 1987). In 1984, on a numerical basis, the
predominant Cladocera were Daphnia galaeta men dot ae f Eubosmina coregoni,.
Bosmina longirostris, Daphnia pul icari a, Daphnia retrocurva and Chydorgs
sphaericus (Table 48). Between 1983 and 1984, essentially the same common
species, with the exception of D. pul icaria, were present with minimal
change in rank abundance. These changes in rank order may be attributed
to the difference in the seasonal sampling pattern between 1983 and 1984.
On a biomass basis, Daphnia pul icaria was the dominant Cladocera for
the lake, with a major bloom in August. It was most prominent in the
central and eastern basins (Fig. 61a). A reexamination of the August 1983
samples revealed that JD. pul icaria was present. Apparently the taxonomist
included this species under Daphnia spp. in the 1983 counts (N. Andresen,
Personal Communication). The existence of the Iarge J). pul icaria is a
major finding. This species was first observed in Lake Michigan in 1978
(Evans 1985) and was a dominant species in 1983 in Lake Michigan and the
third most important cladoceran in Lake Huron in 1983 (Makarewicz 1987).
The occurrence of this species in large numbers in Lake Erie may be an
important factor, along with decreasing phosphorus loading, in explaining
the decreasing phytoplankton abundance observed in Lake Erie (This study).
Large populations of Daphnia pul icaria have been correlated with low algal
biomass (Osgood 1983, Vanni 1983).
A rare species in the offshore waters of the western basin in 1929-30
(Tidd 1955), Chydorus sphaericus was a prominent constituent in the 1950's
(Davis 1962) and in 1970 with a higher abundance in the western basin
(Watson and Carpenter 1974). In 1983 and 1984, this species contributed
0.2$ and 0.1$, respectively, of the total abundance (Makarewicz 1987)
-------
911
(Table 48). Chydoriis sphaerlcus has established Itself as a common
species in Lake Erie.
The prevalence of Cyclops vernal Is has changed over the past 50
years. In the 1930's, £. vernal is was found only in the extreme western
end of Lake Erie at the mouth of the Detroit and Maumee Rivers (Tidd
1955). By 1967 it had spread throughout the lake (Davis 1969b). Fatal as
(1972) and Watson (1976) reported it as numerous in the western basin of
Lake Erie during the late 60's and 70's. This species was not observed in
1983 (Makarewicz 1987), while in 1984 it was not common (Table 48) but did
average 25.9 organisms/m for the entire lake. However, It was more
prevalent in the western basin (83/m ) as compared to the eastern and
central basins (3.3/m ).
The dominant cyclopoid copepod in 1970 was Cyclops bicuspIdatus
thomasi with tyesocycjpps edax common In the summer (Watson and Carpenter
1974). Cap (1980) documented a shift in predominant copepods in the
eastern basin from calanoids in 1928 to cyclopoid copepods, mainly Cyclops
Mcuspidatus t homas i, in 1974. Trppocyclops pr 35 ings was present in low
numbers (Watson and Carpenter 1974). In 1983 and 1984, the same three
species (£. JjLcuspidatgs thomasi, N|. edax and J. praglnus) predominated
(Makarewicz 1987) (Table 48).
Abundance of Diaptomus siciIoides has increased in Lake Erie (Gannon
1981). It was most prevalent in the western basin and western portion of
the central basin in the late 60's and 70's (Patalas 1972, Watson 1976).
Abundant diaptomids in the eastern and central basins in 1970 were
Diaptomus oregonensis and J2. siciloides, which were also the predominant
calanoids in Lake Erie in 1983 and 1984 (Makarewicz 1987) (Table 48). D.
-------
92
sic!loides was not a common species (1.0$ of total zooplankton) in 1984
but was the second most abundant calanofd.
Rot i fera
Davis' studies (1968, 1969a) of the zooplankton of Lake Erie included
rotifers. Certain soft-bodied rotifers were not identified nor were the
samples quantitative for rotifers as a number 20 net was employed.
However, it is apparently the only lake-wide study of the offshore that
included the rotifers.
Species observed to be abundant in 1967 were Brach ionus angular is, E.
calyciflorus, Conoch iI us unicornis, KeratelI a coch|ear is, J< quadrata,
KelIicottia Ipngisp inaf Synchaeta sty I ata and Polyarthra vulgaris (Davis
1968, 1969a). In 1983 a similar group of abundant rotifers was found
(Makarewicz 1987). In decreasing order of relative abundance ($ of total
abundance), the abundant species in 1983 were: Polyarthra vulgaris
(18.4$), Synchaeta sp. (9.5$), Keratella cochI ear is (7.3$), ConochiI us
unicornis (5.3$), Keratella hiemalis (3.5$), Rrachionus sp. (3.0$)
(Makarewicz 1987). Polyarthra vulgaris (22.49$) and Synchaeta sp. (9.46$)
were still dominant in 1984 along with Notholca sguamula (11.06$), which
was not a common species in 1983. Other abundant rotifers in 1984
included Polyarthra major (4.94$), Keratella cochI ear is (4.91$) and
Notholca laurentiae (3.21$) (Table 48). Except for the addition of the
species of Notholca in 1984, the 1983 and 1984 rotifer composition was
similar to 1967. Although it was only the fourteenth most abundant
rotifer, KelIicottia longispina was still prevalent in 1983, but not 1984,
representing 1.3$ of the total abundance (Makarewicz 1987). Only
Keratella quadrata was apparently not as prominent in 1983 and 1984 as it
was in 1967.
-------
93
East-West Species Distribution
Numerous researchers (e.g. Davis 1969b, Watson 1974, Fatal as 1972,
Gannon 1981) have documented the differences in species composition and
abundance from the central, western and eastern basins of Lake Erie. As
in 1983 (Makarewicz 1987), a number of species, all rotifers in 1984, had
higher abundances in the western basin (Figs. 59a&b). Geographically,
Cyclops bicusp idatus thomast, Mesocyclops edax and Diaptomus oregonensis
had geographical abundance patterns with maxima in the central basin !n
1983 (Makarewicz 1987) and 1984 (Fig. 61a). Ho I opediurn gibberum (1983)
and Tropocyclops prasinus mexicanus (1983 and 1984) were more prevalent in
the eastern basin (Fig. 61b).
Indicators of Trophic Status
Zooplankton have potential value as assessors of trophic status
(Gannon and Stemberger 1978). Rotifers, in particular, respond more
quickly to environmental changes than do the crustacean plankton and
appear to be sensitive Indicators of changes in water quality (Gannon and
Stemberger 1978). Brach ionus angularisf E« calyciflorus, FiIinia
long iseta and Trichocerca multicrinis are four rotifer species indicative
of eutrophy. Also, species in the genus Brach ionus are particularly good
indicators of eutrophy in the Great Lakes (Gannon 1981). Of the three
dominant rotifer species in Lake Erie, £. vulgar is Is a eurytopic species;
Notholea squamuls is a cold stenotherm often associated with
oligo-mesotrophic lakes (Gannon and Stemberger 1978) during the summer
that is also often encountered in eutrophic lakes during the winter or
early spring (as In Lake Erie in 1984); and some species of Synchaeta are
eutrophic indicators (Gannon and Stemberger 1978). The lack of dominance
of eutrophic indicator species for the entire lake suggests that Lake Erie
-------
94
in 1984, as a unit, is not eutrophic. This would agree well with the
conclusion from the phytoplankton indicator species and from the algal
biomass classification of trophic status of Lake Erie..
However, the eutrophic indicators Brach ionus caudatus, E.
calyciflorus, fi.. angular is, F i Ii n i a longiseta, Trichocerca muI tier in is and
Trichocerca cylindrica had abundances restricted to or significantly
higher in the western basin (Table 49). Total zooplankton abundance was
also higher in the western basin. As with phytoplankton biomass and
species composition, both rotifer abundance and species composition
indicated a greater degree of eutrophy in the western basin than in the
central or eastern basins.
Another measure of trophic status is the caIanoid/cylopoid plus
cladoceran ratio (plankton ratio) (Gannon and Stemberger 1978, McNaught et
al. 1980a, Krieger 1981). Calanoid copepods generally appear best adapted
for oligotrophic conditions, while cladocerans and cyclopoid copepods are
relatively more abundant in eutrophic waters (Gannon and Stemberger 1978).
In Lake Erie, this ratio increased from west to east in 1983 and 1984
(Table 50) indicating a more productive status for the western basin as
compared to the rest of the lake.
The higher algal biomass (Table 39) of the western basin as compared
to the central and eastern basins was reflected in the higher abundance of
zooplankton, eutrophic zooplankton species composition and the low
plankton ratio. Compared to Lakes Huron and Michigan in 1983 and 1984,
abundance of zooplankton was greatest and the plankton ratio
was lower in Lake Erie (Table 6), indicating the higher trophic status of
Lake Erie compared to Lakes Huron and Michigan.
-------
95
Historical Changes fn Abundances
Zooplankton data exists for the western basin of Lake Erie from 1939
to 1984. The 1939 (Chandler 1940; 49 collections), 1949 (Bradshaw 1964;
30 collections) and 1959 (Hubschmann 1960; daily collections July and
August) collections were taken with a 10-1 iter Juday trap equipped with a
64-um mesh net in the western basin. A 1970 study by Nalepa (1972) is not
included in the analysis because it is from the far western end of the
basin and may not be representative of the entire western basin. The 1961
study of Brltt et al. (1973) sampled twice monthly from mid-June to
mid-September, while Davis (1968) used a 76-um mesh net in July of 1967.
Because of the comparable net sizes, all these studies, with the exception
of Nalepa's (1972), are comparable to the 1983 (Makarewicz 1987) and 1984
surveys.
A comparison of the ApriI-December Crustacea means of 1939, 1949,
1983 and 1984 suggests an increase in zooplankton abundance from 1939 to
1949 (Fig. 63). Similarly, the mean abundance for July and August from
1939 to 1961 suggests a similar increase in zooplankton (Fig. 64). Both
Bradshaw (1964) and Gannon (1981) concluded similarly. Average ice-free
abundances from 1949 to 1983 suggest a decreasing but insignificant
downward trend (Fig. 63). A major decrease in zooplankton abundance is
suggested from 1983 to 1984 (Fig. 63). It is difficult to evaluate this
drop in biomass because of the large gap in data from 1950 to 1983. It
could simply be annual natural variability. However, the Huron and
Michigan zooplankton abundance did not display such a great variability
from 1983 to 1984. Focusing on July and August, where more data are
available, an abundance decrease in Cladocera, Copepoda and total
Crustacea from the 1961 maximum (Fig, 64) is evident.
-------
A data point in the early 70's would be of interest. Data do exist
for the 70's. However, Nalepa's (1972) study is from the far western
portion of the western basin. Watson and Carpenter (1974) sampled the
western basin, as welI as the central and eastern basins in 1970. Their
data is reported as a weighted lake average and is not available to
compare with other years in the western basin. As the sampling method
(1970; vertical hauls, 64-um mesh) is comparable to those used in 1983 and
1984, these data are also directly comparable on a lake-wide basis. A
seasonal comparison of weighted lake-wide means suggests little change in
zooplankton abundance from 1970 and 1983 during the spring and autumn.
However, 1984 values are generally lower than 1983 and 1970 data points
(Fig. 65). The importance of a sampling point between mid-May through
July in 1983 and 1984, the generally recognized period of peak abundance,
is apparent from this figure.
The 1939 and 1961 rotifer samples were collected with a 64-um mesh
net, as in the 1983 and 1984 works. An increase in Rot ifera abundance in
the western basin is suggested since 1939 (Fig. 66).
Trophic Interactions
Long-term changes of phytoplankton and zooplankton abundance were
apparent. A 56 to 76$ reduction in lake-wide offshore algal biomass has
occurred from 1970 to 1983 to 1984. Total phosphorus and chlorophyll .a
levels in each basin decreased (Figs. 53 and 54). Similarly, where
comparable data are available, zooplankton abundance and biomass decreased
in the western basin, while a decrease in lakewide zooplankton biomass
during the summer period from 1970 to 1984 is suggested. With the N/P
ratio currently exceeding 30 to 1, apparently due to P-control, nuisance
blue-green algae species, such as Aphanizomenon flos-aquaf decreased.
-------
97
These changes are consistent with expectations of long-term nutrient
control .
There are, however, significant changes in the composition of the
zooplankton community that can not be attributed solely to nutrient
control. The appearance of the large cladoceran Daphnig pulicar Ia in Lake
Erie was evident in 1983 and 1984. Its dominance with a major bloom in
August of 1984 was surprising for it suggested changes in planktivory in
Lake Erie (Wells 1970, Brooks and Dodson 1965, Carpenter el al. 1985,
Scavia et al. 1986).
A recovery in the walleye fishery of Lake Erie is evident by the
increasing harvest and abundance (Fig. 67). Annual walleye harvest
rapidly increased from 112,000 fish in 1975 to 2.2 million fish in 1977 in
the Ohio Lake Erie waters (western and central basins) (Ohio Department of
Natural Resources 1985). Annual harvests since 1978 have stayed high but
ranged from 1.7 million to the record 4.1 million in 1984 (Ohio Department
of Natural Resources 1985). Central basin harvests have increased
dramatically over the past two years (Fig. 68). The initial recovery of
the walleye fishery is attributed to the closing of the walleye fishery in
1970 due to mercury contamination and to the exclusion of commercial
fishing for walleyes in U.S. waters since 1972 (Kutkahn et al. 1976).
In addition, salmonid stocking programs exist In New York,
Pennsylvania, Ohio and Ontario. New York, which has the largest stocking
program, has a target stocking of -1 million fish in 1987 (F.Cornelius,
Personal Communication). Lake trout, Chinook and Coho salmon and various
strains of rainbow/steel head trout are stocked in New York waters. These
fish are primarily feeding on smelt (NYSDEC 1987).
-------
98
Seasonal diets of walleye closely followed changes in forage-fish
availability (Knight et al. 1984). Between 1979 and 1981 in the western
basin of Lake Erie, walleye ate (100$ by volume) age-1 shiners Notropis
atherinoldes (emerald shiner) and U. hudsonius (spottail shiner) in spring
but switched to age-0 clupeids (60-90$) Dorpsoma cepedianum (gizzard shad)
and Alosa pseudoharengus (alewife) in late July. Clupeids and shiners
composed 25-70$ and 10-40$, respectively, of the diets of age-1 or older
walleyes in autumn (Knight et al. 1984). There does appear to be a
difference in walleye foraging from west to east. Recent stomach analyses
of walleye from New York and Pennsylvania waters indicate that smelt
represent 90$ of their diet (NYSDEC 1987 and R. Kenyon, Personal
Communication,). Smelt are not abundant in the western and central
basins.
Dramatic changes have occurred in the forage species of Erie. It is
apparent that alewife, spottail shiner and emerald shiner have declined in
the western and central basins (Fig. 69) and in Pennsylvania waters (R.
Kenyon, Personal Communication). The decline of spottail and emerald
shiners between 1982-1984 is impressive in view of the massive increase in
walleye harvest in the central basin since 1982 (Fig. 68). Fishery
biologists have no specific reason for this decline. Besides predation,
other possible causes of the decline include climatic factors, turbidity
changes, toxic chemicals and the commercial bait industry. Whatever the
cause, a decrease In planktivorous shiners has occurred.
Emerald and spottail shiners feed heavily on microcrustacean, some
midge larvae and algae (Scott and Grossman 1973, Smith and Kramer 1964,
McCann 1959). Evidence gathered by Gray (1942) in Lake Erie during
December indicated that Diaptomusf Daphnia, Cyclops and Bosmi na were a I I
-------
99
important in the diet of the emerald shiner but at different times of the
day. Dymond (1926) noted that in the spottail shiner of Lake Nipigon,
Daphnia formed 40$ of the diet although Bosmfna, Sidg and Leptodorg were
also eaten. A study on current shiner diets would be useful to the
ongoing discussion on trophic interaction in Lake Erie.
There is good evidence that pianktivorous fish abundance has changed
as a result of the walleye resurgence but perhaps also from the salmonid
stocking program in Lake Erie. Release from planktivore pressure could
have led to the establ ishment of the large Daphnia pulicaria in Lake Erie.
Other top-down effects are difficult to evaluate. For instance, a clearer
water column, as observed in Lake Michigan and attributed to cascading
effects (Scavia et al. 1986), is difficult to evaluate in Lake Erie. For
example, the decrease in Aphanizomenon flos-aquge in Lake Erie is more
readily attributed to decreased phosphorus concentration and the
increasing N/P ratio (Smith 1983) than the influence of large zooplankton
such as Daphnia pulicaria on the phytoplankton assemblage (Lynch 1980,
Bergquist et a I 1985). However, the reappearance and dominance of
Aster tone I I a formosp in 1984 may be related to the presence of fi.
pulicarjg (e.g. Bergquist et al. 1985). In an ecosystem dominated by
large and more efficient herbivores, such as Daphnia pul icaria,. a grazing
effect on phytoplankton would be expected.
The index of dispersion (Elliot 1971) indicates a highly contagious
distribution of phytoplankton and zooplankton In Lake Erie. Could the
patchy distribution of phytoplankton be related to zooplankton herb ivory
on phytoplankton; that is, was there top down control (i.e. grazing) on
phytoplankton on a short-term basis? Table 51 lists correlation
coefficients of phytoplankton abundance versus total phosphorus and
-------
100
zooplankton abundance for each cruise on Lake Erie. For each cruise, 11
stations were sampled covering the entire length of the lake over a short
period of time. Interpretation of the correlations were as follows: A
negative correlation between a zooplankton group and phytoplankton implied
grazing pressure on phytoplankton, while a positive correlation between
total phosphorus and phytoplankton abundance would suggest an enhancement
of phytoplankton abundance due to phosphorus.
All correlations were positive in April, suggesting that phosphorus
was influencing the food web. A different situation was evident by May.
Phytoplankton were blooming (Fig. 45) and all zooplankton groups increased
in abundance (Fig. 56). High negative correlations existed for
zooplankton suggesting a top-down influence on phytoplankton abundance.
Interestingly, a negative correlation existed for TP versus phytoplankton
implying that phosphorus was not the major factor controlling
phytopl ankton abundance on this spring date. As expected, when B..
pulfearia became dominant in August, a negative fairly high correlation
existed betwen J3. pulicgria and phytoplankton. During this same period,
Daphnia spp., in general, and Rot ifera were not negatively correlated
spatially with changes in phytoplankton abundance. By December, other
species of Daphnia and Calanoida exerted some influence on phytoplankton
abundance.
Calanoids were negatively correlated with phytoplankton abundance
throughout the year, except in April, suggesting a constant baseline
effect on phytoplankton abundance. In a lake such as Erie, where a large
efficient Daphnia sp. is added to the food web, the new species induces
grazing pressures previously not present during the summer. Thus during
the summer, a greater grazing pressure leads to a decrease in algae, an
-------
101
increase in transparency and a decrease In turbidity. A decrease in
turbidity during the August bloom of U. pulicaria was observed in Lake
Erie in 1984 (Fig. 70). Turbidity levels in the central and western
basins have decreased since 1978 (Table 52). Similarly, a large increase
in transparency was attributed to grazing of D, pulicaria in Lake Michigan
(Scavia et al. 1986).
Except for the May bloom, total phosphorus positively correlated well
with phytoplankton abundance spatially on Lake Erie. At least two factors
were controlling the phytoplankton abundance. Because of the higher
correlation, it is tempting to suggest that phosphorus was the primary
control on phytoplankton abundance. This was not true during the spring
phytoplankton bloom where zooplankton obviously affected the bloom.
Although P-control was evident during the summer, there were also fairly
high negative correlations between phytoplankton and Daphnia pulicaria and
calanoids. This exercise suggests that "top down" and "bottom up"
control of the trophic web of lake ecosystems exists simultaneously and
that it varies with season.
-------
102
LITERATURE CITED
Ah Istrom, E.H. 1936. The deep water plankton of Lake Michigan,
exclusive of the Crustacea. Trans. Amer. Microsc. Soc. 55: 286-299.
Arnold, D.E. 1971. Ingest ion, assimilation, survival, and reproduction
by Daphnia pulex fed seven species of blue-green algae. Limnol. Oceanogr.
16: 906-920.
Balcer, M.D., N.L. Korda and S.I. Dodson. 1984. Zooplankton of the Great
Lakes. Univ. Wisconsin Press, Madison, Wisconsin. 174 p.
Bartone, C.R. and C.L. Schelske. 1982. Lake-wide seasonal changes in
limnological conditions in Lake Michigan in 1976. J. Great Lakes Res.
8(3): 413-427.
Bergquist, A.M., S.R. Carpenter and J.C. Latino. 1985. Shifts in
phytoplankton size structure and community composition during grazing by
contrasting zooplankton assemblages. Limnol. Oceanogr. 30(5): 1037-1045.
Boesch, D.F. and R. Rosenberg. 1981. Responses to stress in marine
benthic communities. _Ln G.W. Barrett and R. Rosenberg (eds.). Stress
Effects on Natural Ecosystems; 179-200. John Wiley and Sons Ltd.
Bottrell, H.H., A. Duncan, Z.M. Gliwfcz, E. Grygierek, A. Herzig, A.
Hi IIbricht-lIkowska, H. Kurasawa, P. Larsson and T. Weglenska. 1976. A
review of some problems in zooplankton production studies. Norw. J. Zoo I.
24: 419-456.
Bradshaw, A.S. 1964. The crustacean zooplankton picture: Lake Erie
1939-49-59, Cayuga 1910-51-61. Verh. Inter. Verein. Limnol. 15: 700-708.
Britt, N.A., J.T. Addis and R. Angel. 1973. Limnological studies of
western Lake Erie. Bull. Ohio Biol. Surv. 4: 88 p.
Brooks, A.S. and B.G. Torke. 1977. Vertical and seasonal distribution of
chlorophyll .a in Lake Michigan. J. Fish. Res. Board. Can. 34: 2280-2287.
Brooks, J.L. 1969. Eutrophication and changes in the composition of
zooplankton, pp. 236-255. In Eutrophication, Causes, Consequences,
Correctives. National Academy of Sciences. Wash., D.C.
Brooks, J.L. and S.I. Dodson. 1965. Predation, body size, and
composition of plankton. Science. 150: 28-35.
•
Cap, R.K. 1980. Comparative study of zooplankton from the eastern basin
of Lake Erie in 1928 and 1974. Ohio J. Sci. 80: 114-118.
Carpenter, S.R., J.F. Kitchell and J.R. Hodgson. 1985. Cascading trophic
interactions and lake ecosystem productivity. Bioscience. 35: 634-639.
-------
103
Chandler, D.C. 1940. Limnological studies of western Lake Erie. 1.
Plankton and certain physical-chemical data of the Bass Islands region,
from September 1938 to November 1939. Ohio J. Sci. 40: 291-336.
Claflln, L.W. 1975. A multivariate data analyses of Lake Michigan
phytoplankton. Ph.D. Thesis, Univ. of Wisconsin, Madison.
Cornel ius, F. 1987. Lake Erie Unit. New York State Department of
Conservation.
Crumpton, W.G. and R.G. Wetzel. 1982. Effects of differential growth and
mortality in the seasonal succession of phytopIankton populations.
Ecology. 63: 1729-1739.
Davis, C.C. 1962. The plankton of the Cleveland Harbor area of Lake Erie
in 1956-1957. Ecol. Monogr. 32: 209-247.
Davis, C.C. 1964. Evidence for the eutrophication of Lake Erie from
phytoplankton records. Limnol. Oceanogr. 9(3): 275-283.
Davis, C.C. 1968. The July 1967 zooplankton of Lake Erie. Proc. 11th
Conf. Great Lakes Res., pp. 61-75. Inter. Assoc. Great Lakes Res.
Davis, C.C. 1969a. Plants in Lakes Erie and Ontario and changes of their
numbers and kinds, 1969. Bull. Buffalo Soc. Nat. Sci. 25(1): 18-44.
Davis, C.C. 1969b. Seasonal distribution, constitution and abundance of
zooplankton in Lake Erie. J. Fish. Res. Bd. Can. 26: 2459-2576.
Depinto, J.V., T.C. Young and L.M. Mcllroy. 1986. Great Lakes Water
Quality Improvement. Environmental Science and Technology. 20(8):
754-759.
DeVault, D.S. and D.C. Rockwell. 1986. Preliminary results of the
1978-1979 Lake Erie Intensive Study - phytopIankton. Unpublished Draft
Report. Great Lakes National Program Office, EPA, Chicago.
Dillon, P.J., K.H. Nicholls and G.W. Robinson. 1978. Phosphorus removal
at Gravenhurst Bay. An 8-year study on water quality changes. Verh.
Internat. Verein. Limnol. 20: 263-277.
Doohan, M. 1973. An energy budget for adult Brachionus piicatiI is Muller
(Rotator I a). Oecologia. 13: 351-362.
Downing, J.A. and F.H. Rigler. 1984. A Manual on Methods for the
Assessment of Secondary Productivity in Fresh Waters. IBP Handbook #17.
Blackwell Sclent ific Publications, Oxford.
Dumont, H.J., I. van de Velde and S. Dumont. 1975. The dry weight
estimate of biomass in a selection of Cladocera, Copepoda and Rotifera
from the plankton, periphyton and benthos of continental waters.
Oecologia. 19: 75-97.
-------
104
Dymon, J.R. 1926. The fishes of Lake Nipigon. Univ. Toronto Stud. Biol.
Ser. 27, Publ. Ont. Res. Lab. 27: 1-108.
Eddy, S. 1927. The plankton of Lake Michigan. III. Nat. Hist. Surv.
Bui I. 17(4): 203-222.
Elliot, J.M. 1971. Some Methods for the Statistical Analyses of Samples
of Benthic Invertebrates. Scientific Publication No. 25. Freshwater
Biological Association.
Evans, M.S. 1983. Crustacean and rotifer zooplankton of Lake Huron.
1980. Factors affecting community structure with an evaluation of water
quality status. Univ. Michigan. Great Lakes Res. Division, Spec. Report
97.
Evans, M.S. 1985. The morphology of Daphnia pulicaria, a species newly
dominating the offshore southeastern Lake Michigan summer Daphnia
community. Trans. Amer. Micro. Soc. 104(3): 223-231.
Evans, M.S. 1986. Lake Huron rotifer and crustacean zooplankton,
April-July, 1980. J. Great Lakes Res. 12(4): 281-292.
Evans, M.S., B.E. Hawkins and D.W. Sell. 1980. Seasonal fluctuation of
zooplankton assemblages In the nearshore area of southeastern Lake
Michigan. J. Great Lakes Res. 6(4): 275-289.
Fenwick, M.G. 1962. Some interesting algae from Lake Huron. Trans. Am.
Microsc. Soc. 81: 72-76.
Fenwick, M.G. 1968. Lake Huron distribution of TabelI aria fenestrata
var. geniculata A. Cleve and Coelastrum reticulation var. polychordon
Korshik. Trans. Am. Microsc. Soc. 87: 376-383.
Gannon, J.E. 1971. Two counting cells for the enumeration of zooplankton
micro-crustacea. Trans. Amer. Micros. Soc. 90: 486-490.
Gannon, J.E. 1975. Horizontal distribution of crustacean zooplankton
along a cross-lake transect in Lake Michigan. J. Great Lakes Res. 1(1):
79-91.
Gannon, J.E. 1981. Changes in zooplankton populations of Lakes Erie and
Ontario. In R.K. Cap and V.R. Frederick, Proc. of Conference on Changes in
the Biota of Lakes Erie and Ontario. Bull. Buffalo Soc. Nat. Sci. 25(4):
21-39.
Gannon, J.E. and R.S. Stemberger. 1978. Zooplankton (especially
crustaceans and rotifers) as indicators of water quality. Trans. Amer.
Microsc. Soc. 97(1): 16-35.
Gannon, J.E., F.J. Bricker and K.S. Bricker. 1982a. Zooplankton
community composition in nearshore waters of southern Lake Michigan.
EPA-905/3-82/001.
-------
105'
Gannon, J.E., K.S. Bricker and F,J. Bricker, 19826. Zooplankton
community composition in Green Bay, Lake Michigan. EPA-905/3-82-002.
Gladish, D.W. and M. Munawar. 1980. The phytoplankton biomass and
species composition at two stations in western Lake Erie, 1975-76. Int.
Revue ges. Hydrobiol. 65(5): 691-708.
Gliwicz, Z.M. 1980. Filtering rates, food size selection, and feeding
rates in cladocerans - Another aspect of interspecific competition in
filter-feeding zooplankton. Jja W.C. Kerfoot (ed.). Evolution and Ecology
of Zooplankton Communities. Hanover, NH, Univ. Press New England, pp.
282-291.
GLNPO Data Base. Great Lakes National Program Office. 1980.
Phytop I ankton DataBase, Lake Huron. EPA, Chicago, Illinois.
Gray, J.W. 1942. Studies of Notropis atherinoldes Rafinesque in the Bass
Island region of Lake Erie. M.S. Thesis. Ohio State University. Cited
In Scott, W.B. and E.J. Grossman. 1973, Freshwater Fishes of Canada.
Bulletin 184. Fish. Res. Bd. Can., pp. 1-966.
Hawkins, B.E. and M.S. Evans. 1979. Seasonal cycles of zooplankton
biomass in southeastern Lake Michigan. J. Great Lakes Res. 5: 256-263.
Hohn, M.H. 1969. Qualitative and quantitative analyses of plankton
diatoms, Bass Island area, Lake Erie, 1938-1965, including synoptic
surveys of 1960-1963. OhioBiol. Surv. 3(1): 1-211.
Holland, R.E. 1980. Seasonal fluctuations of major diatom species at
five stations across Lake Michigan, May 1970-October 1972. EPA-600/6-066.
Holland, R.E. and A.M. Beeton. 1972. Significance to eutrophteat ion of
spatial differences in nutrients and diatoms in Lake Michigan. Limnol.
Oceanogr. 17: 88-96.
Holm, N.P. and D.E. Armstrong. 1981. Role of nutrient limitation and
competition in control I ing the populations of Asterionella formosa and
Microcystis aeruginosa in semi continuous culture. Limnol. Oceanogr. 26:
622-634.
Hubschmann, J.H. 1960. Relative daily abundance of planktonlc Crustacea
in the island region of western Lake Erie. The Ohio J. of Science.
60(6): 335-340.
Hutchinson, G.E. 1967. A Treatise on Limnology. Vol. II. Introduction
to Lake Biology and LimnopIankton. J. Wiley & Sons, N.Y. 1115 p.
Johannson, 0.E., R.M. Dermot, R. Feldkamp and J.E. Moore. 1985. Lake
Ontario Long Term Biological Monitoring Program: Report for 1981 and
1982. Canadian Technical Report of Fisheries and Aquatic Sciences. No.
1414, i-xvi + 208 p.
-------
1Q6
Johnson, D.L. 1972. Zooplankton population dynamics in Indiana waters of
Lake Michigan In 1970. Cited in J.E. Gannon, F.J. Bricker and K.S.
Bricker. 1982. Zooplankton community composition in nearshore waters of
southern Lake Michigan. EPA-905/3-82/001.
Jude, D.J. and F.J. Tesar. 1985. Recent changes In the forage fish of
Lake Michigan. Can. J. Fish. Aquat. Sci. 42: 1154-1157.
Kenyon, R. Personal Communication. Pennsylvania Fish Commission.
Kilham, S.S. and P. Kilham. 1978. Natural community bioassays:
Predictions of results based on nutrient physiology and competition.
Verh. Int. Ver. Limnol. 20: 68-74.
Kilham, P. and D. Tilman. 1979. The importance of resource competition
and nutrient gradients for phytoplankton ecology. Arch. Hydrobiol. Beih.
Ergebn. Limnol. 13: 100-119.
Kitchell, J.F. and S.R. Carpenter. 1986. Piscfvores, pianktivores,
fossils and phorbins. J_n W.C. Kerfoot (ed.). Predation: effects on
aquatic communities. University Press of New England, Hanover, NH. (In
press).
Knight, R.L., F.J. Margraf and R.F. Carl ine. 1984. Piscivory by walleyes
and yellow perch in western Lake Erie. Trans. Amer. Fish. Soc. 113:
677-693.
Krieger, K.A. 1981. The crustacean zooplankton of the southern nearshore
zone of the central basin of Lake Erie in 1978 and 1979: Indications of
trophic status. Unpublished Report. Available from the Great Lakes
National Program Office, EPA, Chicago.
Kutkuhn, J. and coauthors. 1976, First Technical Report of the Great
Lakes Fishery Commission Scientific Protocol Committee on Interagency
Management of the Wai I eye Resource of Western Lake Erie. Great Lakes
Fishery Commission, Ann Arbor, Michigan.
Lange,C. and R. Cap. 1986. B ithptrephes cederstroemi (Schodler).
(Cercopagidae: Cladocera): A new record for Lake Ontario. J. Great Lakes
Res. 12(2):142-143.
Lesht, B.M. and D.C. Rockwell. 1987. The State of the Middle Great
Lakes: Results of the 1984 Water Qual ity Survey of Lakes Erie, Huron and
Michigan. Argonne National Laboratory Publication Number ANL/ER-87-1,
Argonne, 111 inois.
Likens, G.E. and J.J. Gilbert. 1970. Notes on quantitative sampling of
natural populations of planktonlc rotifers. Limnol. Oceangor. 15:
816-820.
Lin, C.K. and C.L. Schelske. 1978. Effects of nutrient enrichment, light
intensity and temperature on growth of phytoplankton from Lake Huron.
EPA-600/3-79-049.
Lynch, M. 1980. Aphanizomenon blooms: Alternate control and cultivation
by Daphnia pulex. Am. Soc. Limnol. Oceanogr. Symp. 3: 299-304.
-------
107
Makarewicz, J.C. 1987. Phytoplankton annd zooplankton composition,
abundance and distribution: Lake Erie, Lake Huron and Lake Michigan -
1983. U.S.E.P.A. Great Lakes National Program Office, Chicago,11 Iinois.
EPA-905/2-87-002.
Makarewicz, J.C. and G.E. Likens. 1979. Structure and function of the
zooplankton community of Mirror Lake, N.H. Ecol. Monogr. 49: 109-127.
McCann, J.A. 1959. Life history studies of the spottail shiner of Clear
Lake, Iowa, with particular reference to some sampling problems. Trans.
Amer. Fish. Soc. 88(4): 336-343.
McNaught, D.C., M. Buzzard, D. Griesmer and M. Kennedy. 1980a.
Zooplankton grazing and population dynamics in relation to water quality
in southern Lake Huron. EPA-600/3-80-069.
McNaught, D.C., D. Griesmer and M. Kennedy. 1980b. Resource
characteristics modifying selective grazing by copepods. In W.C. Kerfoot
(ed.). Evolution and Ecology of Zooplankton Communities. Hanover, NH,
Univ. Press New England, pp. 292-298.
Michalski, M.F.P. 1968. PhytopIankton levels in Canadian near-shore
waters of the lower Great Lakes. Proc. 11th Conf. Great Lakes. Res.
85-95. Internat. Assoc. Great Lakes Res.
Moll, R.A., R. Rossmann, D.C. Rockwell and W.Y.B. Chang. 1985. Lake
Huron Intensive Survey, 1980. Special Report No. 110. Great Lakes
Research Division. The University of Michigan. Ann Arbor, Michigan.
Mortonson, J.A. 1977. The vertical distribution of chlorophyll .a and
nutrients at a deep station in Lake Michigan. M. Sci. Thesis, Univ.
Wisconsin, Milwaukee.
Munawar, M. and N.M. Burns. 1976. Relationships of phytoplankton biomass
with soluble nutrients, primary product!Ion and chlorophyll .2 in Lake
Erie, 1970. J. Fish. Res. Bd. Can. 33: 601-611.
Munawar, M. and I.F. Munawar. 1975. The abundance and significance of
phytoflagellates and nannopIankton in the St. Lawrence Great Lakes. Verh.
Int. Verein. Limnol. 19: 705-723.
Munawar, M. and I.F. Munawar. 1976. A lakewlde survey of phytoplankton
biomass and its species composition in Lake Erie, Apr!I-December 1970. J.
Fish. Res. Bd. Can. 33: 581-600.
Munawar, M. and I.F. Munawar. 1979. A preliminary account of Lake Huron
phytoplankton, Apr!I-December 1971. Fish. Mar. Serv. Tech. Rep. 917.
1-15 p.
Munawar, M. and I.F. Munawar. 1982. Phycological studies in Lakes
Ontario, Erie, Huron and Superior. Can. J. Bot. 60(9): 1837-1858.
Nalepa, T.F. 1972. An ecological evaluation of a thermal discharge.
Part III: The distribution of zooplankton along the western shore of Lake
-------
108-
Erie. Mich. State Univ., Inst. Water Res., Thermal Discharge Series,
Tech. Rept. No 15. 111 p.
Nauwerck, A. 1963. The relation between zooplankton and phytoplankton in
Lake Erken. Symb. Bot. Ups. 17: 163.
New York State Department of Environmental Conservation . 1985. 1985
Annual Report for the Bureau of Fisheries - Lake Erie Unit. NYSDEC.
Albany, N.Y.
New York State Department of Environmental Conservation . 1987. 1987
Annual Report for the Bureau of Fisheries - Lake Erie Unit. NYSDEC.
Albany, N.Y.
Nicholls, K.H. 1981. Recent changes in the phytoplankton of Lakes Erie
and Ontario, in R.K. Cap and V.R. Frederick, Proc. of Conference on
Changes in the Biota of Lakes Erie and Ontario. Bull. Buffalo Soc. Nat.
Sci. 25(4): 41-85.
Nicholls, K.H., E.C. Carney and G.W. Robinson. 1977a. Phytop Iankton of
an inshore area of Georgian Bay, Lake Huron, prior to reductions in
phosphorus loading. J, Great Lakes Res. 3(1-2): 79-92.
Nicholls, K.H., D.W. Standen, G.J. Hopkins and E.C. Carney. 1977b.
Declines in the nearshore phytoplankton of Lake Erie's western basin since
1971. J. Great Lakes Res. 3(1-2): 72-78.
Nicholls, K.H., D.W. Standen and G.J. Hopkins. 1980. Recent changes in
the nearshore phytoplankton of Lake Erie's western basin at KIngsville,
Ontario. J. Great Lakes Res. 6(2): 146-153.
Ohio Department of Natural Resources. 1985. Status and Trend Highlights
on Ohio's Lake Erie Fish and Fisheries. J_a Great Lakes Fishery
Commission, Lake Erie Committee 1985 Annual Meeting.
Osgood, R.A. 1983. Long-term grazing control of algal abundance: A case
history. J_n Lake and Reservoir Management, Proceedings of the Third
Annual Conferecne of the North American Lake Management Society, 1983.
Knoxville, TN.
Parkos, W.G., T.A, Olson and T.O. Odlaug. 1969. Water quality studies on
the Great Lakes based on carbon fourteen measurements on primary
productivity. Univ. Minnesota-Minneapolis, Water Resour. Res. Center
Bui I. 17: 1-121.
Patalas, K. 1972. Crustacean plankton and the eutrophication of St.
Lawrence Great Lakes. J. Fish. Res. Bd. Can. 29(10): 1451-1462.
Pejler, B. 1965. Regional-ecological studies of Swedish freshwater
zooplankton. Zool. Bidrag. Fran. Uppsala. 36: 405-515.
Porter, K.G. 1973. Selective grazing and differential digestion of algae
by zooplankton. Nature. 244: 179-180.
-------
109
Porter, K.G. and J.D. Orcutt, Jr. 1980. Nutritional adequacy,
manageability, and toxicity as factors that determine the food quality of
green and blue-green algae for Daphnia. Jn W.C. Kerfoot (ed.). Evolution
and Ecology of Zooplankton Communities. Hanover, NH, Univ. Press New
England, pp. 268-281.
Rathke, D.E. 1984. Lake Erie Intensive Study 1978-1979. U.S.E.P.A.
Publication EPA-905/4-84-001, Great Lakes National Program Office,
Chicago, 11 Iinois.
Reuter, J.E. 1979. Seasonal distribution of phytoplankton biomass in a
nearshore area of the central basin of Lake Erie, 1975-1976. Ohio J. Sci.
79(5): 218-226.
Rockwell, D.C., D.S. DeVault, M.F. Palmer, C.V. Marion and R.J. Bowden.
1980. Lake Michigan Intensive Survey 1976-1977. U.S.E.P.A. Great Lakes
National Program Off ice, Chicago, Illinois. EPA-905/4-80-003-A. 154 p.
Scavia, D., G.L. Fahnenstiel, M.S. Evans, D.J. Jude and J. Lehman. 1986.
Influence of salmonine predation and weather on long-term water quality in
Lake Michigan. Can. J. Fish. Aquat. Sci. 43: 435-441.
Schelske, C.L. and E.F. Stoermer. 1971. Eutrophication, silica depletion
and predicted changes in algal quality in Lake Michigan. Science. 173:
423-424.
Schelske, C.L., E.F. Stoermer and L.E. Feldt. 1971. Nutrients,
phytoplankton productivity and species composition as influenced by
upwelting in Lake Michigan. Proc. 14th Conf. Great Lakes Res., Int.
Assoc. Great Lakes Res. pp. 102-113.
Schelske, C.L. and E.F. Stoermer. 1972. Phosphorus, silica and
eutrophication in Lake Michigan. In G.E. Likens (ed.). Nutrients and
Eutrophication: The Limiting-nutrient Controversy. Special Symposium.
Vol. 1, ASLO, pp. 157-171.
Schelske, C.L., L.E. Feldt, M.A. Santiago and E.F. Stoermer. 1972.
Nutrient enrichment and its effect on phytoplankton and species
composition in Lake Superior. Proc. 15th Conf. Great Lakes Res., Int.
Assoc. Great Lakes Res., pp. 149-165.
Schelske, C.L., L.E. Feldt, M.S. Simmons and E.F. Stoermer. 1974. Storm
induced relationships among chemical conditions and phytoplankton in
Saginaw Bay and Western Lake Huron. Proc. 17th Conf. Great Lakes Res.,
pp.78-91. Internet. Assoc. Great Lakes Res.
Schelske, C.L., E.F. Stoermer, J.E. Gannon and M.S. Simmons. 1976.
Biological, chemical and' physical relationships in the Straits of
Mackinac. Univ. Mich., Great Lakes Res. Div. Spec. Rept. 60, 267 p.
Scott , W.B. and E.J. Grossman. 1973. Freshwater Fishes of Canada.
Bulletin 184. Fish, Res. Board Canada.
-------
no
Smith, V.H. 1983. Low nitrogen to phosphorus ratios favor dominance by
blue-green algae fn lake phytoplankton. Science. 221:669-671.
Smith, L.L. and R.H. Kramer. 1964. The spottai! shiner in Lower Red
Lake, Minnesota. Trans. Amer. Fish. Soc. 93(1): 35-45.
Stemberger, R.S. 1979. A guide to rotifers of the Laurentian Great Lakes.
U.S. Environmental Protection Agency, Rept. No. EPA 600/4-79-021, 185 p.
Stemberger, R.S., J.E. Gannon and F.J. Bricker. 1979. Spatial and
seasonal structure of rotifer communities in Lake Huron.
EPA-600/3-79-085.
Stemberger, R.S. and M.S. Evans. 1984. Rotifer seasonal succession and
copepod predation in Lake Michigan. J. Great Lakes Res. 10(4): 417-428.
Stevenson, R.J. 1985. Phytoplankton - composition, abundance and
distribution In Lake Huron. U.S.E.P.A. Publication EPA-905/3-85-004,
Great Lakes National Program Office, Chicago, Illinois.
Stewart, D.J., J.F. KitchelI and L.B. Crowder. 1981. Forage fishes and
their salmonid predators in Lake Michigan. Trans. Am. Fish. Soc. 110:
751-763.
Stoermer, E.F. 1978. Phytoplankton assemblages as indicators of water
quality in the Laurentian Great Lakes. Trans. Amer. Micros. Soc. 97(1):
2-16.
Stoermer, E.F. and E. Kopczynska. 1967a. PhytopIankton populations in
the extreme southern basin of Lake Michigan, 1962-1963. Proc. 10th Conf.
Great Lakes Res., pp. 88-106. Int. Assoc. Great Lakes Res.
Stoermer, E.F. and E. Kopczynska. 1967b. Phytoplankton populations in
the extreme southern basin of Lake Michigan, 1962-1963, pp. 19-40. In
J.C. Ayers and D.C. Chandler. Studies on the environment and
eutrophication of Lake Michigan. Univ. Michigan, Great Lakes Res. Div.,
Spec. Rep. No. 30.
Stoermer, E.F. and R.G. Kreis. 1980. Phytoplankton composition and
abundance in southern Lake Huron. EPA-600/3-80-061. 383 p.
Stoermer, E.F. and T.B. Ladewski. 1976. Apparent optimal temperatures
for the occurrence of some common phytoplankton species in southern Lake
Michigan. Great Lakes Res. Div., Univ. Michigan. Publ. 18. 49 p.
Stoermer, E.F., C.L. Schelske, M.A. Santiago and L.E. Feldt. 1972.
Spring phytoplankton abundance and productivity in Grand Traverse Bay,
Lake Michigan, 1970. 15th Conf. Great Lakes Res. 1972: 181-191. Intern.
Assoc. Great Lakes Res.
Stoermer, E.F. and R.J. Stevenson. 1979. Green Bay phytoplankton,
composition, abundance and distribution. EPA-905/3-79-002.
-------
w
Stoermer, E.F. and E. Theriot. 1985. Phytop Iankton distribution in
Saginaw Bay. J. Great Lakes Res. 11(2): 132-142.
Stoermer, E.F. and M.L. Tuchman. 1979. PhytopIankton assemblages of the
nearshore zone of southern Lake Michigan. EPA-905/3-79-001. 89 p.
Stoermer, E.F. and J.J. Yang. 1970. Distribution and relative abundance
of dominant plankton diatoms. Univ. Michigan, Great Lakes Res. Div., Pub.
No. 16. 64 p.
Tarapchak, S.J. and E.F. Stoermer. 1976. Environmental status of the
Lake Michigan region. ANL/ES-40.
Tidd, W.M. 1955. The zooplankton of western Lake Erie, pp. 200-248. In
S. Wright (ed.). Limnological Survey of Western Lake Erie. U.S. Fish &
Wildl. Serv., Spec. Rept. - Fish, No. 139. 341 p.
Tilman, D. 1978. The role of nutrient competition in a predictive theory
of phytoplankton population dynamics. Mitt. Int. Ver. Limnol. 21:
585-592.
Tilman, D. 1980. Resources: A graphical-mechanistic approach to
competition and predation. Amer. Nat. 116: 363-393.
Utermbhl, H. 1958. Zur vervolIkommung der quantitativen
phytoplankton-methodik. M.H. Int. Ver. Limnol. 9. 38 p.
Vanni, M.J. 1983. Biological control of nuisance algae by Daphnia pulex;
Experimental studies. In Lake and Reservoir Management, Proceedings of
the Third Annual Conference of the North American Lake Management Society,
1983. Knoxville, TN.
Verduin, J. 1964. Changes in western Lake Erie during the period
1948-1962. Verh. Int. Ver. Limnol. 15: 639-644.
Vollenweider, R.A. 1968. Scientific fundamentals of the eutrophication
of lakes and flowing waters with particular reference to nitrogen and
phosphorus as factors in eutrophication. Organ. Econ. Coop. Dev. Rep.,
Paris.
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. Bd. Canada. 31: 739-762.
Watson, N.H.F. 1974. Zooplankton of the St. Lawrence Great Lakes -
Species composition, distribution and abundance. J. Fish. Res. Bd. Can.
31: 783-794.
Watson, N.H.F. 1976. Seasonal distribution and abundance of crustacean
zooplankton in Lake Erie, 1970. J. Fish. Res. Bd. Can. 33: 612-621.
Watson, N.H.F. and G.F. Carpenter. 1974. Seasonal abundance of
crustacean zooplankton and net plankton biomass of Lakes Huron, Erie and
Ontario. J. Fish. Res. Bd. Can. 31: 309-317.
-------
112
Wells, L. 1960. Seasonal abundance and vertical movements of planktonic
Crustacea In Lake Michigan. U.S. Fish Wildlife Serv. Fish. Bull. 60:
343-369.
Wells, L. 1970. Effects of alewife predation on zooplankton populations
in Lake Michigan. Limnol. Oceanogr. 15: 556-565.
Wells, L. and A.M. Beeton. 1963. Food of the bloater, Coregones hoyI, in
Lake Michigan. Trans. Amer. Fish. Soc. 92(3): 245-255.
Wells, L. and R.W. Hatch. 1983. Status of bloater chubs, alewives,
smelt, slimy sculpln, deepwater sculplns and yellow perch in Lake
Michigan, 1983. Presented at the Great Lakes Fishery Commission. Lake
Michigan Committee Meeting, Duluth, Minnesota, March 19, 1984.
Whittaker, R.H. 1975. Communities and Ecosystems. MacMillan Publishing Co.
Inc. N.Y., N.Y.
Willen, T. 1959. The phytoplankton of Gorwalm, a bay of Lake Malaren.
Oikos. 10: 241-274.
Williams, L.G. 1966. Dominant rotifers of the major waterways in the
United States. Limnol. Oceanogr. 11: 83-91.
-------
113
TABLE 1. Plankton sampling dates for Lakes Michigan, Huron and Erie in
1984 and 1985. Only phytoplankton samples were taken during the winter
helicopter cruises of 1985.
1984
1985
Cruise
1
2
3
4
5
6
7
8
9
10
11
Lake
Michigan
4/9-12
5/6-7
-
7/8-9
8/1-3
8/12-14
8/15-16
11/27-29
12/13-18
-
2/7-9
Lake
Huron
4/12-15
5/4-5
-
7/5-7
8/3-4
8/10-12
8/17-18
11/30-12/2
12/10-12
1/15-16
2/9-10
Lake
Erie
4/18-19
4/20-21
5/1-2
7/2-3
8/5-6
8/7-9
8/19-20
12/4-5
12/5-8
1/14-14
2/17-18
-------
114
TABLE
1984.
2. Latitude and longitude of plankton sampling stations,
Station
Number
LAKE ERIE
LE60
LE57
LE55
LE42
LE73
LE37
LE78
LE79
LE18
LE15
LE09
Latitude
41°53'30"
41 49 54
41 44 18
41 57 54
41 58 40
42 06 36
42 07 00
42 15 00
42 25 18
42 31 00
42 32 18
Longitude
83°11'48"
83 01 06
82 44 00
82 02 30
81 45 25
81 34 30
81 15 00
80 48 00
80 04 48
79 53 36
79 37 00
LAKE HURON
LH93
LH92
LH91
LH90
LH61
LH57
LH54
LH53
LH48
LH45
LH43
LH38
LH37
LH34
LH32
LH29
LH27
LH15
LH12
LH09
LH06
44 06 00
43 48 30
43 42 00
43 24 00
45 45 00
45 40 00
45 31 00
45 27 00
45 16 42
45 08 12
45 00 48
44 44 24
44 45 42
44 38 24
44 27 12
44 22 00
44 11 54
44 00 00
43 53 24
43 38 00
43 28 00
82 07 00
82 22 00
82 01 00
82 18 00
83 55 00
83 43 36
83 25 00
82 54 54
82 27 06
82 59 00
82 00 30
82 03 36
82 47 00
83 13 54
82 20 30
81 50 00
82 30 12
82 21 00
82 03 24
82 13 00
82 00 00
-------
115
Table 2 (continued).
LAKE MICHIGAN
LM05 42 00 00 87 25 00
LM06 42 00 00 87 00 00
LM10 42 23 00 87 25 00
LM11 42 23 00 87 00 00
LM17 42 44 00 87 25 00
LM18 42 44 00 87 00 00
LM22 43 08 00 87 25 00
LM23 43 08 00 87 00 00
LM26 43 36 00 87 22 00
LM27 43 36 00 86 55 00
LM32 44 08 24 87 14 00
LM34 44 05 24 86 46 00
LM40 44 45 36 86 58 00
LM41 44 44 12 86 43 18
LM46 45 13 24 86 36 48
LM47 45 10 42 86 22 30
LM56 45 37 30 86 18 00
LM57 45 38 12 86 03 30
LM64 45 57 00 85 35 12
LM77 45 47 24 84 49 24
-------
116
TABLE 3. Sample dates and stations for Lake Michigan, 1984 and 1985.
Station 4/9 5/6 7/8 8/1 8/12 8/15 11/27 12/13 2/7
Number
5
6
10
11
17
18
22
23
26
27
32
34
40
41
46
47
56
57
64
77a
XXX X
X X X X X
XXX X
X X X X X
XXX X
X X X X X
X XXX
XX X XX
X XXX
XX X XX
X XXX
XX X XX
X XXX
XX X XX
XXX X
X X X X X
XXX X
X X X X X
xxxxxxxx
xxxx xxxx
-------
117
Table 4. Sample dates and stations for Lake Huron, 1984 and 1985.
Station 4/ 5/ 7/ 8/ 8/ 8/ ll/ 12/ I/ 2/
Number 12-15 4-5 5-7 3-4 10-12 17-18 27-2 10-13 15-16 9-10
6 x xx xx
90 x x xxx
9x xx xx xx
91 x x
12 x xx xx
92 x x x
15 x xx xx xx
27 x xx xx
93 x x x
29 x x x
32 x xx xx
34 xx
37 x xx xx xx
38 x x x
43
i 45
]
I 48
1
53
1 54
57
61
XX X
X XX XX XX
XX X
XX X
X XX XX X
XX XX
X XX XX X
-------
118
TABLE 5. Comparison of calculated crustacean dry weights (ug) to
measured dry weights in Lake Michigan. Measured weights from Hawkins and
Evans (1979).
Calculated
Measured
Species
Cyclops bicuspidatus
thomasi
Cyclops vernalis
Diaptomus ashlandi
Diaptomus minutus
Diaptomus oregonensis
Diaptomus sicilis
Limnocalanus macrurus
Tropocyclops prasinus
mexicanus
Cyclopoid copepodite
Bosmina longirostris
Chydorus sphaericus
Daphnia galeata mendotae
Daphnia retrocurva
Eubosmina coregoni
Holopedium gibberum
Polyphemus pediculus
Epischura lacustris
Eurytemera affinis
mean
weight
4.2
8.6
2.6
2.4
5.1
7.1
29.3
1.3
.7
1.4
1.9
10.0
5.2
2.5
12.0
13.6
9.4
4.9
mean
length
.97
.97
.96
.93
1.26
1.44
2.57
.59
.54
.39
.34
1.32
1.04
.49
.95
.87
1.61
1.25
range
3.0-5.3
5.9-12.2
2.2-3.2
1.9-2.9
3.2-6.7
5.3-10.2
20.5-35.0
0.9-1.8
0.2-1.4
0.6-3.2
1.7-2.1
2.6-20.1
1.6-11.2
0.9-6.1
6.3-20.2
4.3-36.9
5.4-13.0
_
(n)
63
8
65
63
45
61
59
59
65
39
4
42
26
36
1>3
6
22
1
mean
we ight
3.2
1.9
5.6
2.5
4.8
3.9
3.2
2.8
6.9
5.6
17.3
11.4
45.3
33.8
.9
1.2
1.0
1.0
4.0
2.9
1.7
5.0
2.9
10.8
4.8
range
1.9-5.6
1.2-2.9
4,8-6.4
2.4-2.6
2.1-7.1
1.9-5.6
1.7-4.9
1.8-4.4
3.8-10.9
3.3-10.1
13.4-23.6
8.6-11.4
13.2-88.2
16.7-55.8
0.7-1.2
0.6-2.2
0.6-1.8
0.8-1.2
2.5-8.9
1.2-6.5
1.2-2.5
1.9-10.9
2.2-4.1
5.9-13.9
3.9-5.3
-------
119
Table 6. Mean values (±S.E.) of physical-chemical parameters
(April-October) from a 1-m depth for Lakes Erie, Michigan and Huron* 1984.
Values are in mg/L unless noted otherwise. Values in parentheses represent
number of samples analyzed. Phytoplankton samples are from April to February.
Zooplankton samples are from April to November. The trophic ratio and
zooplankton ratio are discussed in the text.
Erie
Michigan
Huron
pH
Alkalinity
Conductivity (umhos/cm)
Turbidity (NTU)
Soluble Reactive
Silica (mg/L)
Chloride
Sulfate
Nitrite + Nitrate
Total phosphorus (ug/L)
Soluble Reactive
Phosphorus (ug/L)
Sodium
Potassium
Chi a
Phytoplankton
(1000x*/mL)
(g/m3)
Zooplankton
(1000x*/m )
(mg/m )
Trophic ratio
Zooplankton ratio
8.25±.03(101)
92.5+.43U06)
272.4+1.54(106)
4.5±.85(88)
178.9+21.7(106)
14.61+.25(105)
22.70+.20U05)
0.29±.02(106)
16.55+1.41(105)
2.0+.33UOO)
7.18±.16(32)
1.40±.02(32)
3.45+.3K105)
45.1+4.2 (117)
1.0±.08(117)
159.6+25.3(65)
53.6±6.2(65)
1.8
0.35
8.23+.03(83)
106.9+.56(85)
273±1.38(85)
.39+.03(75)
360.1±22(85)
8.79+.08(85)
21.22+.14(84)
0.22+.006(85)
4.63±.24(84)
0.92+.KK71)
4.75±.03(30)
1.30+.OK30)
0.86+.05(84)
22.2+1.4(97)
0.55+.038(97)
59.8±8.3(65)
33.2+4.9(65)
4
0.64
8.02+.03(101)
77.4±.31(106)
202.9+.83(106)
0.32+.02(88)
644.6±19.9(106)
5.66±.05(105)
16.09+.1K105)
0.30+.004(106)
3.70+.25(105)
0.80+.10UOO)
3.17±.05(32)
0.94±.01(32)
0.64+.04(105)
17.2+.89(95)
0.38±.10(95)
55.4+7.2(49)
27.3±2.3(49)
3.8*
1.50
* Average of 1983 and 1984
-------
120
TABLE 7. Number of species and genera observed in each algal
division or grouping in Lake Michigan. 1983 and 1984. Results are
for the non-winter period.
Division Species Genera
1983 1984 1983 1984
Bacillariophyta 168 166 33 29
Chlorophyta 86 63 36 26
Chrysophyta 49 33 13 11
Cryptophyta 23 20 44
Cyanophyta 21 13 10 8
Picoplankton (2)1 3 (2)1 3
Colorless flagellates 16 15 65
Pyrrhophyta 97 43
Euglenophyta 11 11
Unidentified 55 -
Chlorotnanophyta 10 10
Total 379 327 108 91
Included in Cyanophyta in 1983
-------
121
TABLE 8. Relative abundance of major phytoplankton divisions in
Lake Michigan, 1983 and 1984. Bac=Bacillariophyta,
Cat=Chloromanophyta, Chl=Chlorophyta, Ohr=Chrysophyta,
Col=Color less flagellates, Cry=Cryptophyta, Cya=Cyanophyta»
Pic=Picoplankton, Eug=Euglenophyta, Pyr=Pyrrhophyta,
Uni=Unidentified.
Biovolume/mL Cells/mL
Division 1983 1984 1983 1984
Bac
Cat
Chi
Chr
Col
Cry
Cya
Pic
Eug
Pyr
Dni
56.41
0.02
5.25
6.53
0.75
13.43
5.56*
-
0.04
7.32
4.68
69.97
0.00
1.99
5.01
0.41
11.61
1.65
1.39
0.07
2.36
5.53
1.07
0.01
0.65
1.49
0.13
1.24
92.21
-
0.01
0.01
3.20
2.04
0.00
0.67
2.18
0.30
1.50
3.54
82.85
<0.01
0.02
6.89
*Picoplankton are included with the Cyanophyta
in 1983.
-------
122
Table 9. Abundance of Rhizosolenia eriensis in Lake Michigan in 1983
and 1984. Values in parentheses represent &. eriensis+R. longiseta.
4/17
4/26
5/4
7/4
8/3
8/17
10/12
10/26
1983
Date cells/mL % biovolume
0.0
0.0
0.2
0.0
0.0
0.0
10.9
7.1
0.0
0.0
0.1
0.0
0.0(.05)
0.0
9.1(9.2)
2.1(10.7)
1984
Date cells/mL % biovolume
4/9
5/6
7/8
8/1
8/12
8/15
11/27
12/13
2/7
10.3
9.3
52.4
22.6
17,
21,
3.2
8.3
4.8
.5
.9
17.5(30.5)
8.6(17.4)
33.4(36.1)
23.2(25.0)
26.9(30.1)
39.2(44.6)
7.9 (8.3)
16.4(17.0)
4.6 (5.2)
-------
123
TABLE 10. Summary of common phytoplankton species occurrence in Lake Michigan daring 1984 and winter
of 1985. Summary is based on all samples analyzed. Summary includes the maximum population density
encountered, the average population density and biovolume. and the relative abundance (Z of total
cells and Z of total biovolune). Common species were arbitrarily defined as having an abundance of
X3.1X of tbe total cells or >0.5I of tbe total biovolnme.
Taxon
BACILLARIOPHVTA
Asterionella formosa
Cyclotella comensis v. 1
Cyclotella comta
Cyclotella ocellata
Fragilaria capucina
Fragilaria crotonensis
Meloaira islandica
Helosira italica snbsp. subarctic*
Nitzschia lauenburgiana
Khizosolenia eriensis
Rhizosolenia longiseta
Stepbanodiscus alpinus
Stephanodiscus alpinus?
Stephanodiscua niagarae
Stepbanodiscus transilvanicus
Synedra filifoncis
Synedra ulna v. cbaseana
Tabellaria flocculoaa
CHLOROPHTTA
Honoraphidium contortun
Oocystis submarina
Dictyosphaerium ehrenbergianum
CHKSOPHYTA
Cbrysophycean coccoids
Diaobryon divergens
Dinobryon sociale v. americanum
Haptophyte sp.
COLORLESS FLAGELLATES
Colorless flagellates
Honosiga ovata
CRYPTOPHITA
Chroomonas norstedtii
Cryptomonas erosa
Cryptomonas marsaonii
Cryptomonas rostratifornis
Khodomonas minuta v. nannoplanktica
CYASOPHYTA
Anacystis montana v. minor
Coelosphaerium naegelianum
Oscillatoria limnetica
Oscillatoria minima
PICOPLAWCTON
rods
spheres
spherical - flagellates
FYKRBOPKfTA
Gymnodinium sp.
Peridinium sp.
UNIDENTIFIED
Unidentified flagellate - ovoid
Unidentified flagellate - spherical
Maximum
Cells/mL
184
2. 568
96
265
161
376
96
74
10
110
162
18
11
14
7
118
23
82
344
254
278
630
303
1,743
1.456
311
352
270
65
25
25
965
2,790
982
2,070
4.132
4.287
43.541
2.847
16
16
4.287
1.350
Average
Cells/ml
22.4
115.6
4.4
23.3
11.9
74.3
12.6
10.8
0.7
18.2
21.2
2.2
0.7
1.1
0.8
11.2
2.2
13.9
36.8
25.8
23.6
83.1
26.5
111.7
182.3
26.5
24.5
48.8
11.2
3.7
1.3
232.5
292.6
31.9
209.8
175.5
886.6
16.716.3
805.6
0.5
1.5
1.0026.3
503.2
Z of Total
Cells
0.10
0.52
0.02
0.10
0.05
0.33
0.06
0.05
0.00
0.08
0.10
0.01
0.00
0.01
0.00
0.05
0.01
0.06
0.17
0.12
0.11
0.37
0.12
0.50
0.82
0.12
0.11
0.22
0.05
0.02
0.01
1.05
1.32
0.14
0.94
0.79
3.99
75.23
3.63
0.00
0.01
4.62
2.26
Mean
Biovolume
urn /mL
6.130
3.539
11.561
2.079
3.940
48.175
13.538
2.784
4.506
129.063
23.928
8.318
4.267
17.571
16,294
4.225
17.151
41.459
385
417
196
320
5.443
11.052
1.633
424
310
1.480
25.171
4.948
4,572
17.683
1,276
153
1.023
3.737
2.415
4.481
714
4.111
4.275
23.103
6.771
Z of Total
Biovolume
1.12
0.65
2.12
0.38
0.72
8.83
2.48
0.51
0.83
23.64
4.38
1.52
0.78
3.22
2.99
0.77
3.14
7.60
0.07
0.08
0.03
0.06
1.00
2.02
0.30
0.08
0.06
0.27
4.61
0.91
0.84
3.24
0.23
0.03
0.19
0.68
0.44
0.82
0.13
0.75
0.78
4.23
1.24
-------
124
TABLE 11. Common species observed in either 1983 or 1984» but not
both years, Lake Michigan. Common species were arbitrarily defined
as having an abundance of >0.1% of the total cells or >0.5% of the
total biovolume.
1983
1984/1985
Bacillariophyta
Cyclotella michiganiana
Cymatopleura solea
Entomoneis ornata
Fragilaria vaucheriae
Tabellaria fenestrata
Cyclotella ocellata
Rhizosolenia longiseta
Nitzschia lauenburgiana
Synedra filiformis
Synedra ulna v. chaseana
Chlorophyta
Cosmarium sp.
Stichococcus sp,
Oocystis submarina
Dictyosphaerium ehrenbergianum
Chrysophyta
Dinobryon cylindricum
Stylotheca aurea
Cryptophyta
Cryptomonas erosa v. reflexa
Cryptomonas pyrenoidifera
Cryptomonas rostratiformis
Cyanophyta
Gomphosphaeria naegelianum
Oscillatoria agardhii
Oscillatoria minima
Pyrrhophyta
Ceratium hirundinella
-------
125
Table 12. Number of species in Lake Michigan with depth at Station 47,
15 August 1986.
Division
Depth
(m)
1
5
10
15
20
Bac
13
11
30
23
27
Chi
1
3
4
5
10
Chr
9
9
7
7
8
Cry
5
4
5
3
6
Cya
1
2
2
3
5
Pic
3
3
3
3
3
-------
125
TABLE 13. Comparison of abundance of Cyclotella species at offshore
sites in August of 1970, 1983 and 1984, Lake Michigan. Data from
Holland and Beeton (1972), Makarewicz (1987) and this study. Stations
22 and 27 are geographically comparable to Holland and Beeton's offshore
sites. Values are in cells/mL.
11 August 70 17 August 83 15 August 84
(offshore stations) (Stations 22&27) (Stations22&27)
Cyclotella
michiganiana 71 - 182 0.44 - 6.8 0.38 - 4.5
Cyclotella
stelligera 300 - 613 0.17 - 2.2 1.7 - 2.8
-------
127
TABLE 14. Comparison of nutrient levels between Stations 6, 64, 77 and
all other stations during the spring and fall, Lake Michigan. Mean+j>.E.
Station 77
Station 64
Lake Mean
( exc lud ing
Station 77)
Silica
(ug/L)
632.7+23.2
364.5+22.8
501.0+14.4
Total
Phosphorus
(ug/L)
4.67+1.08
6.35+2.16
5. 14+. 35
Nitrate +
Nitrite
(mg/L)
.27+.01
.20+. 01
.26+.01
Station 6
502.8+38.9
4.05+.41
.27±.01
-------
128
TABLE 15. Distribution of indicator diatom species in Lake Michigan.
The classification scheme followed Tarapchak and Stoermer (1976).
M,=mesotrophic but intolerant of nutrient enrichment• M =mesotrophic and
tolerant of moderate nutrient enrichment. E=eutrophic. 1970-71, 1977
and 1983 data are from Holland and Beeton (1972), Stoermer and Tuchman
(1979) and Makarewicz (1987).
Ml
6
5
6
5
M2
5
3
2
3
E
7
1
2
2
M1+M2'
1.6
8.0
4.0
4.0
19772(Nearshore)
1970-713
19831
19841
Only diatoms contributing >.5% of the biomass for a cruise
are classified.
2 Only diatoms contributing >1% (1977) or >0.1% (1984) of the
abundance are classified.
3
Only "predominant" species are classified.
-------
129
Table 16. Relative abundance of zooplankton in Lake Michigan.
Percent Percent
Abundance
Rot ifera
Cladocera
Copepoda nauplii
Cyclopoida
Calanoida
Mysidacea
Harpacticoida
1983 1984 1983 1984
N
0
T
C
A
L
C
U
L
A
T
E
D
2
39
11
15
30
0
<
.6
.8
.2
.8
.4
.2
.1
59
3
21
5
10
<
<
.7
.2
.3
.7
.1
.1
.1
67.5
4.1
15.6
6.2
6.6
<.01
<.01
-------
130
TABLE 17. Summary of common zooplankton species occurrence in Lake
Michigan during 1984. Values are from the short zooplankton hauls only.
Species were arbitrarily classified as common if they accounted for
>0.1% of the total abundance or 1.0% of the total biomass, with the
exception of rotifers. Rotifer species were considered common if they
accounted for >1.0% of the total abundance.
Taxon
COPEPODA
Copepoda - nauplii
Cyclopoida
Cyclopoid - copepodite
Cyclops bicuspidatus
thomasi
Tropocyclops prasinus
mexicanus
Calanoida
Diaptomus - copepodite
Diaptomus ashlandi
Diaptomus minutus
Diaptomus sicilis
Limnocalanus macrurus
CLADOCERA
Bosmina longirostris
Daphnia galeata mendotae
Daphnia pulicaria
Daphnia retrocurva
Eubosmina coregoni
Holopedium gibberum
Leptodora kindtii
ROTIFERA
Collotheca sp.
Conochilus unicornis
Gastropus stylifer
Kellicottia longispina
Keratella cochlearis
Notholca foliacea
Notholca laurentiae
Notholca squamula
Polyarthra remata
Polyarthra vulgaris
Synchaeta sp.
Maximum
Dens ity
#/m3
62127
14358
5475
439
30508
5098
695
1062
469
29566
9110
690
5286
1465
4333
255
6814
8850
18843
43489
124128
21396
52609
50381
20550
47790
27545
Average
Density
#/m3
9183
2767
749
60
2518
848
132
2157
56
TOTAL
942
846
78
238
125
136
27
TOTAL
1134
942
1241
5649
11764
798
2325
2200
1105
5785
4223
TOTAL
% of
Total
Density
15.60
4.70
1.27
.10
4.28
1.44
.22
.37
.09
22.07
1.60
1.44
.13
.40
.21
.23
.05
4.06
1.93
1.60
2.11
9.60
19.99
1.36
3.95
3.74
1.88
9.83
7.18
63.15
95.29
Mean
Biomass
ug/m
3673
1797
3057
73
3676
2162
321
1478
1637
876
6825
1638
1389
271
1132
779
8
17
18
49
65
20
77
37
30
82
98
% of
Total
Biomass
11.23
5.50
9.35
.22
11.24
6.61
.98
4.52
5.01
54.67
2.68
20.88
5.01
4.25
.83
3.46
2.38
39.49
.02
.05
.05
.15
.20
.06
.24
.11
.09
.25
.30
1.53
95.69
-------
131
TABLE 18. Cladoceran abundance in 1954, 1966, 1968, 1983 and 1984 in
Lake Michigan. Data from Well^ (1970), Makarewicz (1987) and this
study. Values are in number /m
Species and Year
Leptodora kindtii
1954
1966
1968
1983
1984
Daphnia galeata
1954
1966
1968
1983
1984
Daphnia retrocurva
1954
1966
1968
1983
1984
Diaphanosoma brachyurum
1954
1966
1968
1983
1984
Daphnia longiremis
1954
1966
1968
1983
1984
Daphnia pulicaria
1954
1966
1968
1983
1984
Holopedium gibberum
1954
1966
1968
1983
1984
Polyphemus pediculus
1954
1966
1968
Early
August
29
4
16
34
98
1200
0
0.4
514
3508
1400
79
2100
82
1061
2
0
0
1
0
0
16
0
0
14
0
0
0
1011
248
0
2
5
456
536
2
15
10
-------
132
TABLE
18. (continued)
1983
1984
Bosmina longirostris
1954
1966
1968
1983
1984
Eubosmina coregoni
1954
1966
1968
1983
1984
Ceriodaphnia quadrangula
1954
1966
1968
1983
1984
13
7
26
98
16
342
5231(141)*
0
1
16
159
208
0
4
1
0
0
* Bloom at Station 77 and 64. Mean for the offshore waters
minus Station 77 and 64 is in parentheses.
-------
133
TA.BLE 19. Copepod abundance in 1954, 1966, 1968, 1983 and
1984 in Lake Michigan. Data frgm Wells (1970), Makarewicz (1987) and
this study. Values are number/m.
Early
Species and Year August
Limnocalarms macrurus
1954 91
1966 34
1968 270
1983 18
1984 64
Epischura lacustris
1954 41
1966 7
1968 21
1983 19
1984 14
Diaptomus sicilis
1954 3
1966 1
1968 3
1983 79
1984 155
Mesocyclops edax
1954 200
1966 0
1968 0
1983 13
1984 31
Senecella calanoides
1954 0.2
1966 0.2
1968 0.1
1983 1.4
1984 0
Cyclops bicuspidatus
1954 310
1966 1000
1968 860
1983 1457
1984 2807
Diaptomus ashlandi
1954 140
1966 220
1968 13
1983 1256
1984 1733
Cyclops vernalis
1954 0
1966 0
1968 0
1983 0
-------
134
TABLE 19. (continued).
1984 16
Eurytemora affinis
1954 0
1966 33
1968 3
1983 0
1984 0
Diaptomus oregonensis
1954 63
1966 58
1968 100
1983 138
1984 58
Diaptomus tninutus
1954 39
1966 25
1968 1500
1983 151
1984 183
-------
135
Table 20. Average crustacean zooplankton biomass (dry weight) for 1976
and 1984, Lake Michigan. The 1976 data (Bartone and Schelske 1982) were
converted to dry weight assuming carbon content was 50% of dry weight.
1976 50.0+14.8 mg/m3
1984 33.6+14.7 mg/m3
-------
TABLE 21. The ratio of calanoids to cyclopoids plus cladocerans
geographically in Lake Michigan, 1983 and 1984.
136
Calanolda
at ion
77 (North)
64
57
47
41
34
27
23
18
11
6 (South)
Cyclopoida + (
1983
0.37
0.41
1.74
1.52
1.10
1.03
1.53
1.15
3.01
1.71
0.87
Jladoce:
1984
0.23
0.20
0.69
0.57
0.57
0.80
0.84
1.32
1.93
1.09
0.75
-------
137
Table 22. Correlation of phytoplankton with total phosphorus
concentrations and zooplankton abundance within individual cruises ( 11
stations) in Lake Michigan, 1984. NO = not observed.
4/9-12
5/6-7
8/1-3
8/15-16
11/27-29
12/18
Daphnia
pulicaria
NO
-.132
-.021
-.272
-.171
-.095
Daphnia
spp.
.794
-.327
.137
-.496
-.016
.594
Rot if era
.395
.715
.768
-.031
.680
.763
Calanoida
-.707
-.738
-.059
.243
.455
-.164
Tota
Phosphi
-.385
-.113
.330
.191
-.156
.653
-------
138
TABLE 23. Number of species and genera observed in each algal division
or groupingt Lake Huron, 1983 and 1984.
Division Species Genera
BAG
CHL
CHR
CRY
CYA
PIC
COL
PYR
BUG
UNI
CAT
1983
158
73
36
22
13
(2)*
13
10
4
3
1
1984
156
64
35
17
13
3
13
9
1
4
0
1983
29
28
10
3
6
(2)*
4
4
3
-
1
1984
28
28
12
4
7
3
5
4
1
-
0
Total 329 315 88 92
* Included in Cyanophyta in 1983
-------
139
TABLE 24. Relative abundance of major phytoplankton divisions in Lake
Huron, 1983 and 1984. In 1983 picoplankton are included with the
Cyanophyta. BAC=Bacillariophyta, CAT=Chloromanophyta» CHL=Chlorophyta,
CHR=Chrysophyta, COL=Colorless Flagellates, CRY=Cryptophyta,
CYA=Cyanophyta, PIC=Picoplankton, EUG=Euglenophyta, PYR=Pyrrhophyta»
UNI=Unidenti£ied.
Division Biovo ]uiPft/UlL Cells/mL
BAG
CAT
CHL
CHR
COL
CRY
CYA
PIC
EUG
PYR
UNI
1983
68.20
.02
3.45
7.11
.14
8.29
4.31*
-
.11
3.25
5.11
1984
61.90
0.00
2.72
9.45
.19
9.10
1.41
1.60
.06
7.15
6.41
1983
1.16
.01
.42
1.60
.06
1.13
89.53*
-
.01
.01
6.09
1984
2.78
0.00
.58
2.08
.14
1.24
4.15
83.85
.01
.02
5.14
* Picoplankton included in Cyanophyta in 1983.
-------
14.0
Table 25. Abundance of Rhizosolenia eriensis in Lake Huront 1983 and
1984. Values in parentheses in 1983 represent Rhizosolenia sp. and in
1984 R.. longiseta.
1983
1984
Date cells/mL % biovolume
4/21
5/6
7/2
8/4
8/19
10/16
10/24
0.1
0.2
0.0
0.0
0.0
0.4
0.0
0.01
0.01(38.3)
0.0 (59.2)
0.0 (11.3)
0.0 (12.8)
Date cells/mL % biovolume
1.0
0.0
(6.1)
(8.7)
4/12
5/4
7/5
8/3
8/10
8/17
11/27
12/10
1/15
2/9
6.3
5.4
51.0
26.7
33.1
9.9
5.8
2.9
2.4
10.7
9.0(0.43)
6.3(0.46)
18.1(0.81)
30.4(0.92)
1(0.15)
1(0.51)
1(0.39)
10.3(0.44)
4.4(0.0)
12.4(0.17)
35
29
16
-------
141
TABLE 26, Summary of common phytoplankton species occurrence in Lake Huron during 1984 and winter of 1965*
Summary is based on all samples analyzed. Summary includes the maximum population density encountered*
the average population density and biovolume, and the relative abundance (! of total cells and I of total
biovolume). Common species were arbitrarily defined as having an abundance of >0.1Z of the total cells or
>0.5Z of the total biovolume.
Mean
Taxon Maximum Average X of Total Biovolume Z of Total
cells/ml cells/ml/ Cells um /mL Biovolume
BACIIXARIOPHYTA
Asterionella formosa 168 27.5
Cyclotella comencis 1386 122.2
Cyclotella comta 35 2.3
Cyclotella kuetzingiana v. planetophora? 135 13.2
Cyclotella ocellata 1000 113.2
Cyclotella stelligera 267 25.3
Fragilaria crotonensis 375 44.7
Fragilaria intermedia v. fallax 25 2.6
Melosira islandica 43 6.5
Rhizosolenia eriensis 131 17.2
Rhizosolenia longiseta 33 2.9
Stephanodiscus alpinus 19 1.5
Stephanodiscus minutus 85 19.4
Stephanodiscus niagarae 2 0.2
Tabellaria flocculosa 181 25.0
.16
.71
.01
.08
.66
.15
.26
.02
.04
.10
.02
.01
.11
.00
,15
9.225
5.781
8.178
3.902
9.784
614
39,333
2.233
8.752
81.644
2.355
3.950
851
3.562
69.337
2.13
1.49
1.89
.90
2.26
.14
9.09
.52
2.02
18.87
.54
.91
.20
.82
16.02
CHL080PHYTA
Cosmarium sp.
16
.7
.00
2,173
.5
CHRYSOPHYTA
Chrysopbycean coccoids
Chrysosphaerella longispina
Dinobryon cylindricum
Dinobryon divergens
Dinobryon sociale
Dinobryon sociale v. americanum
Haptophyte sp.
CRYPTOPHYTA
Chroomonas norstedtii
Cryptomonas erosa
Cryptomonas pyrenoidifera
Cryptomonas rostratiformis
Rhodomonas minute v. nannoplanktica
CtANOPHYTA
Anacystis montana v. minor
Coelosphaerium naegelianum
Gomphosphaeria lacustris
Oscillatoria limnetica
Oscillatoria minima
PICOPLANKTON
rods
spheres
spherical - flagellates
PYRRHOPHYTA
Ceratium hirundinella
Gymnodinium helveticum f. achroum
Gymnodinium sp.
Gymnodinium sp. 2
UNIDENTIFIED
Unidentified flagellate - ovoid
Unidentified flagellate - spherical
160
1325
196
254
589
540
589
115
31
33
8
360
4606
1047
851
942
335
2741
29690
2160
36.2
31.3
13.3
32.0
65.6
27.8
110.1
22.8
4.5
4.2
.8
155.1
445.4
77.6
79.0
45.9
17.3
811.6
13021.0
563.2
1481
2193
.1
.2
.5
.3
615.9
264.7
.21
.18
.08
.19
.38
.16
.64
.13
.03
.02
.00
.90
2.59
.45
.46
.27
.10
4.73
75.84
3.28
.00
.00
.00
.00
3.59
1.54
189
8.313
4,298
6.544
10,771
4,716
1.460
724
10,333
2.450
3.290
13,772
2,205
335
380
219
453
2,568
3,768
592
14,991
3,566
3,312
5.816
17.740
9.767
.04
1.92
.99
1.51
2.49
1.09
.34
.17
2.39
.57
.76
3.18
.51
.08
.09
.05
.10
.59
.87
.14
3.46
.82
.77
1.34
4.10
2.26
-------
142
TABLE 27. Common species observed in either 1983 or 1984 but not in
both years. Lake Huron.
1983
Bacillariophyta
Stephanodiscus transiIvanicus
1984/85
Cyclotella stelligera
Stephanodiscus alpinus
Stephanodiscus minutus
Chlorophyta
Cryptophyta
Cosmarium sp.
Cryptomonas rostratiformis
Cyanophyta
Anacystis thermalis
Coccochloris elabans
Oscillatoria minima
-------
143
Table 28. Distribution of indicator diatom species in Lake Huron.
The classification scheme of Tarapchak and Stoermer (1976) was utilized,
M^meso trophic but intolerant of nutrient enrichment, M =me so trophic and
tolerant of moderate nutrient enrichment, E=eutrophic. 1971, 1975-76
and 1983 data are from Munawar and Munawar (1979), Lin and Schelske
(1978) and Makarewicz (1987).
Ml
6
2
7
6
M2
3
4
2
3
E
3
2
2
3
M1+M2
3.0
3.0
4.5
3.0
19711
1975-762
19833
19843
Only diatoms cantributing >5% of the seasonal biomass are
classified.
2
Only "abundant" diatom species are classified.
3
Only diatoms contributing >0.5% of the biomass for the study
period are classified.
-------
144
Table 29. Relative abundance of zooplankton in Lake Huron.
Rotifera
Cladocera
Copepoda nauplii
Cyclopoida
Calanoida
Amphipoda
Mysidacea
Percent Percent
Biomass Abundance
1983 1984 1983 1984
N
0
T
C
A
L
C
U
L
A
T
E
D
2
27
14
13
42
<
0
.5
.5
.7
.3
.0
.1
.0
41
4
23
11
19
0
<
.1
.8
.1
.2
.8
.0
.1
56
2
18
7
15
<
0
.0
.9
.6
.3
.3
.1
.0
-------
145
TABLE 30. Summary of common zooplankton species occurrence in Lake
Huron during 1984. Values are from the short zooplankton hauls only.
Species were arbitrarily classified as common if they accounted for
>0.1% of the total abundance or 1.0% of the total biomass, with the
exception of rotifers. Rotifer species were considered common if they
accounted for >1.0% of the total abundance.
Taxon
Maximum Average % of Mean % of
Density Density Total Biomass Total
///m Density ug/m Biomass
COPEPODA
Copepoda - nauplii
Cyclopoida
Cyclopoid - copepodite
Cyclops bicuspidatus
thomasi
Mesocyclops
copepodite
Mesocyclops edax
Calanoida
Diaptomus - copepodite
Diaptomus ashlandi
Diaptomus minutus
Diaptomus oregonensis
Diaptomus sicilis
Limnocalanus macrurus
CLADOCERA
Bosmina longirostris
Daphnia galaeta
mendotae
Daphnia pulicaria
Eubosmina coregoni
Holopedium gibberum
Leptodora kindtii
ROTIFERA
Collotheca sp.
Conochilus unicornis
Gastropus stylifer
Kellicottia longispina
Keratella cochlearis
Notholca squamula
Polyarthra remata
Polyarthra vulgaris
Synchaeta sp.
24749
12791
1487
3262
270
22584
2960
1306
256
2044
266
3304
4127
935
3441
2124
133
3584
66009
9855
19274
51995
6804
5916
18086
12963
10071
3254
316
300
40
6174
1071
369
93
502
20
TOTAL
338
586
71
326
158
16
TOTAL
672
10878
1094
3784
6652
570
650
2917
1489
TOTAL
18.59
6.01
.58
.55
.07
11.40
1.98
.68
.17
.93
.04
41.00
.62
1.08
.13
.60
.29
.03
2.76
1.24
20.08
2.02
6.99
12.28
1.05
1.20
5.38
2.75
52.99
96.75
4028
1750
1356
205
283
5020
2189
720
363
2377
525
303
3136
1017
709
1658
416
4
239
26
45
24
11
17
117
42
14.73
6.40
4.96
.75
1.03
18.36
8.01
2.63
1.33
8.69
1.92
68.81
1.11
11.47
3.72
2.59
6.06
1.52
26.48
.01
.87
.09
.16
.09
.04
.06
.43
.16
1.92
97.21
-------
146
Table 31. Comparison of mean crustacean abundance for the sampling
period in 1971 (April-November), 1974/75 (April-November), 1983
(August-October) and 1984 (April-December), Lake Huron. 1971 data
modified from Watson and Carpenter (1974), 1974/75 data from McNaught et
al. (1980) and J983 data from Makarewicz (1987). NF = not found. Values
are in number/m
j
Cladocera
Bosmina longirostris
Eubosmina coregoni
Daphnia retrocurva
Daphnia galeata mendotae
Daphnia longiremis
Daphnia pulicaria
Chydorus sphaericus
Holopedium gibberum
Cyclopoida
Cyclops bicuspidatus
thomasi
Cyclops vernalis
Tropocyclops prasinus
mexicanus
Mesocyclops edax
Calanoida
Diaptomus ashlandi
Diaptomus minutus
Diaptomus sicilis
Diaptomus oregonensis
Limnocalanus macrurus
1971
553 (1047)*
330 (765)*
339 (852)*
0 (0)
18
229 (580)*
3764 (3274)*
7.5 (5)*
63 (61)*
5 (6.7)*
246 (37)*
462 (322)*
117 (77)*
109 (92)*
64 (44)*
1974/75** 1983***
4109
2084
361
692
0
391
576
1271
117
310
91
745
966
496
192
34
518
229
74
1029
363
NF
58
2346
.5
577
115
206
465
145
140
9.3
1984
338
326
36
586
71
NF
158
316
1.5
21
40
1071
369
502
93
20
* August, September and October average
** Includes Saginaw Bay
*** August and October average
-------
147
Table 32. Abundance of selected zooplankton species in northern and
mthern Lake Huron in 1984. Valu<
is defined as south of Station 27.
southern Lake Huron in 1984. Values are number/m . Southern Lake Huron
Conochilus Kellicottia Diaptomus Ho lopedium
unicornis longispina minutus gibberum
Northern 12,526 3,897 298 239
Southern 4,729 2,449 383 29
-------
148
TABLE 33. Ratio of Calanoida to Cladocera plus Cyclopoida in Lake
Huron, 1983 and 1984.
Calanoida
Station
61 (North)
54
45
37
32
27
15
12
09
06 (South)
Cyclopoida + Cladocera
1983
0.67
1.11
1.19
1.57
2.13
1.37
1.60
1.98
1.31
1.23
1984
0.90
1.36
1.84
1.33
1.46
1.16
1.83
2.00
1.89
Mean
0.74
1.24
1.52
1.45
1.80
1.27
1.91
1.66
1.56
-------
149
Table 34. Comparison of the plankton ratio
(Calanoida/Cyclopoida+Cladocera) between the northern stations of Lake
Huron and Lake Michigan.
1983 1984 mean
Lake Michigan
Station 77 0.37 0.23 0.32
Lake Huron
Station 61 0.67 0.90 0.78
Lake Mean 1.49 1.61 1.55
-------
150
TABLE 35. Mean abundance of rotifers in Lake Huron in 1974 and 1983. Data
from Stemberger et al. (1979), Makarewicz (1987) and this study. NF = not
found in short tow.
Colletheca sp.
Conochilus unicornis
Filinia longiseta
Gastropus stylifer
Kellicottia longispina
Keratella cochlearis
Keratella earlinae
Notholca squamula
Polyarthra dolichoptera
Polyarthra remata
Polyarthra vulgaris
Synchaeta kitina
Synchaeta stylata
Synchaeta sp.
1974
April-Nov.
#/L
0.8
15.0
3.4
5.2
6.8
41.9
10.9
7.4
3.0
6.8
17.6
8.1
7.1
2.4
1980
April-July
#/L
0.0
0.79
<.01
0.27
1.15
1.86
<.01
1.8
0.12
0.12
0.05
NF
NF
1.03
1983
Aug. -Oct.
#/L
0.90
7.10
0.004
1.10
2.10
2.00
0.08
NF
0.07
0.01
3.00
NF
NF
0.10
1984
April-Dec.
0.67
10.87
0.007
1.09
3.78
6.65
0.10
0.57
0.43
0.65
2.92
NF
NF
1.5
-------
151
Table 36. Correlation (r) of phytoplankton abundance with total
phosphorus concentrations and zooplankton abundance within individual
cruises (10 stations) in Lake Huron» 1984. NO = observed.
5/4-5
8/3-4
8/17-18
11/30-12/2
12/10-13
Daphnia
pu lie aria
-.110
-.258
-.286
-.218
.380
Daphnia
spp.
-.110
-.698
-.060
-.460
.415
Rotifera
.393
.595
-.662
.420
.049
Calanoida
-.370
.010
-.549
.101
-.192
Total
Phospho:
-.032
.144
-.314
-.168
.378
-------
152
Table 37. Number of species and genera observed in each algal division
or grouping, Lake Erie, 1983 and 1984. Bac=Bacillariophyta»
Cat=Chloromanophyta» Chl=Chlorophyta, Chr=Chrysophyta» Col=Colorless
flagellates, Cry=Cryptophyta» Cya=Cyanophyta, Pic=Picoplankton,
Eug=Euglenophyta, Pyr=Pyrrhophyta, Uni=Unidentified.
Species Genera
Division
BAG
CHL
CHR
CRY
CYA
PIC
COL
PYR
BUG
UNI
CAT
1983
176
108
29
14
16
-
15
8
2
3
1
1984
171
96
28
15
18
3*
11
9
0
4
1
1983
30
38
11
3
9
-
6
4
2
0
0
1984
30
38
14
4
10
0
4
4
0
0
0
TOTAL 372 356 103 104
* Included in Cyanophyta in 1983.
-------
153
TABLE 38. Number of species identified and percentage of species
belonging to various taxonomic groups* Lake Erie. 1970 data represent
the mean for the central, western and eastern basins [modified from
Munawar and Munawar (1976)].
Number of Species
Division
BAG
CHL
CHR
CYA
CRY
EUG
PYR
PIC
UNI
COL
1970
134.3
16.3
58.0
6.3
11.2
3.3
0.7
4.0
-
-
_
1983
372
Percent Composition
47.3
29.0
7.8
4.3
3.8
0.5
2.2
-
0.8
4.0
1984
356
48.0
27.0
7.9
5.1
4.2
0.0
0.0
0.8
1.1
3.1
-------
15.4
Table 39. Phytoplankton and zooplankton biomass* total phosphorus and
chlorophyll a. concentrations in the western, central and eastern basins
of Lake Erie, 1983 and 1984. Values are in g/m unless noted otherwise.
estern
1.49
1.38
1.44
Central
1.59
0.76
1.18
Eastern
0.84
0.54
0.69
Entire
Lake
(mean±S.E.
1.36+.12
1.00+.16
1.18
Phytoplankton
1983
1984
mean
Zooplankton
1984 0.055 0.052 0.054 0.053+.0062
1984 (#/L) 295.6 94.3 130.4 159.6±25
Total
Phosphorus
1983(ug/L) 26.77 16.82 12.79
1984(ug/L) 23.91 19.37 12.41
Chlorophyll a
1983(ug/L) 5.68 4.05 2.22
1984(ug/L) 5.10 3.27 2.11
-------
155
TABLE 40. Summary of common phytop lankton species occurrence in Lake Erie during 1984 and winter of 1985.
Summary is based on all samples analyzed. Summary includes the maximum population density encountered,
the average population density and biovolume, and the relative abundance (% of total cells and I of total
biovolume). Common species were arbitrarily defined as having an abundance of >0.1X of the total cells or
>0.5S! of the total biovolume.
Taxon
BACILLARIOPHY1A
Asterionella formosa
Fragilaria capucina
Fragilaria crotonensis
Melosira islandica
Stephanodiscus alpinus
Stephanodiecus binderanus
Stephanodiscus niagarse
Stephanodiscus sp.
labellaria flocculosa
CHLOROPHYTA
Cosmarium sp.
Crucigenia rectangularis
Oocystis borgei
Fedlastrun simplex v. duodenarium
CHRYSOPHYTA
Haptophyte sp.
COLORLESS FLAGELLATES
Colorless flagellates
Stelexmonas dichotoma
CRYPTOPHYTA
Chrooraonas norstedtii
Cryptomonae eroea
Cryptomonas rostratiformie
Rhodomonas minuta v* nannoplanktica
CYANOPHYTA
Anabaena sp.
Anacystis montana v. minor
Aphanizomenon flos-aquae
Coelosphaerium naegelianum
Herismopedia tenuissima
Oscillatoria limnetica
PICOPLANKTON
rods
spheres
spherical - flagellates
PYRRHOPHYTA
Ceratium hirundinella
Gymnodinium sp. 2
Peridinium aciculiferum
Peridinium sp.
UHIDEHTIFIED
Unidentified flagellate - ovoid
Unidentified flagellate - spherical
Maximum
Cells/mL
942
407
826
1564
198
2506
120
781
207
25
295
180
393
1317
2119
1186
425
295
33
2348
1162
22253
2643
3436
6218
5179
10987
379.888
1726
82
33
41
82
4303
2479
Average X of Total
Cells/mL Cells
73.4
38.2
77.9
31.5
8.7
59.2
4.9
78.3
15.8
1.0
5.1
8.0
7.8
151.9
65.2
87.8
50.9
24.3
1.6
499.1
47.8
1052.1
103.6
78.1
85.6
112.7
1.128.5
38,075.3
544.8
2.8
2.2
1.3
5.5
1177.5
558.1
0.16
0.08
0.17
0.07
0.02
0.13
0.01
0.17
0.04
0.00
0.01
0.02
0.02
0.34
0.14
0.19
0.11
0.05
0.00
1.11
0.11
2.33
0.23
0.17
0.19
0.25
2.50
84.46
1.21
0.01
0.00
0.00
0.01
2.61
1.24
Mean Z of Total
Bio volume Biovolume
urn /mL
48,802
10.764
66.983
35,812
17,522
21.539
135.855
6,991
33.732
39.142
10.087
9.357
10.685
2,670
1.619
3.500
1.219
45.760
5,132
39.038
7,603
4.892
7.598
333
103
421
3.154
10.207
644
37.283
31,523
12.634
25.308
51.864
16.609
5.57
1.23
7.53
4.09
2.00
2.46
15.51
0.80
3.85
4.47
1.15
1.07
1.22
0.30
0.18
0.40
0.14
5.23
0.59
4.46
0.87
0.56
0.87
0.04
0.01
0.05
0.36
1.J7
0.07
4.26
3.60
1.44
2.89
5.92
1.90
-------
156
Table 41. Location of maximum abundance of selected species in 1983
and 1984, Lake Erie.
1983
Fragilaria crotonensis
Fragilaria capucina
Melosira granulata
Melosira islandica
Stephanodiscus sp.
Stephanodiscus binderanus
Tabellaria flocculosa
Oscillatoria tenuis
Oscillatoria limnetica
Oscillatoria subbrevis
Anacystis montana var. minor
Aphanizomenon flos-aquae
spheres
Cryptomonas erosa
Chroomonas norstedtii
Merismopedia tenuissima
Pediastrum simplex var. duodenarium
Coelosphaerium naegelianum
Scenedesmus ecornis
Peridinium aciculiferum
Stephanodiscus
Asterionella formosa
Gymnodinium sp.#2
Haptophyte
Western
Western
Western
not common
not common
Western
Western
Western
Western
Western
not common
not common
Western
Western
not common
not common
Central
Central
Central
Central
Central
not common
1984
Western
Western
not common
Western
Western
Western
Western
not common
Western
not common
Western
Western
Western
Western
Western
Western
Western
Western
Western
Central
Western
Central
Central
Central
-------
157
TABLE 42. Common species observed in either 1983 or 1984 but not
both years. Lake Erie. 1983 data are from Makarewicz (1987).
1983
Bacillariophyta
Actinocyclus normanii f. subsalsa
Melosira granulata
Rhizosolenia sp.
1984
Asterionella formosa
Melosira islandica
Stephanodiscus sp.
Chlorophyta
Coelastrum microporum
Monoraphidium contortum
Mougeotia sp.
Scenedesmus ecornis
Staurastrum paradoxum
Crucigenia rectangularis
Cyanophyta
Agemenellum quadruplicatum
Oscillatoria subbrevis
Oscillatoria tenuis
Anacystis sp.
-------
158
TABLE 43. Importance of Asterionella formosa during
the spring of 1984, Lake Erie. Sampling dates: 4/18, 4/20, 5/1/84.
Rank Species
1 Asterionella formosa
2 Fragilaria crotonensis
3 Melosira islandica
4 Gymnodinium sp. #2
B iovolume(g An )
All Species
0.162
0.160
0.123
0.109
Rank Species
1 Stephanodiscus sp.
2 Asterionella formosa
3 Fragilaria crotonensis
4 Stephanodiscus parvus
Abundance (#/mL)
Diatoms
238
224
170
117
-------
159
TABLE 44. Mean maximum bio mass of selected common phytoplankton species in
1970 and 1983, Lake Erie. Data from Munawar and Munawar (1976) and this
study. 1970 data - graphical accuracy. Percent reduction is from 1970 to
1984.
Actinocyclus
normanii
Stephanodiscus
niagarae
Stephanodiscus
tenuis
Stephanodiscus
binderanus
Fragilaria
crotonensis
Fragilaria
capucina
Peridinium
aciculiferum
Ceratium
hirundinella
Rhodomonas
minuta
Cryptomonas
erosa
Pediastrum
simplex
Staurastrum
paradoxum
Aphanizomenon
BASIN
Western
Eastern
Central
Western
Western
Western
Eastern
Central
Western
Central
Eastern
Central
Eastern
Central
Eastern
Eastern
Central
Western
Central
Central
Western
197§
g/m
4.7
1.4
2.3
0.6
1.8
0.5
1.0
3.4
7.9
2.4
0.4
0.2
1.0
1.8
2.0
1.6
0.4
2.0
0.4
0.4
2.0
1983*
g/m
0.30
1.05
2.19
0.12
0.001
0.11
0.15
0.11
0.18
0.02
0.04
0.06
0.05
0.35
0.31
0.04
0.10
0.63
0.06
0.07
0.10
1984.
g/m
0.05
0.22
0.23
0.17
0.002
0.04
0.45
0.16
0.29
0.03
0.01
0.18
0.03
0.13
0.35
0.05
0.14
0.40
0.00
0.00
0.09
Percent
Reduction
99
84
90
72
99
92
54
95
96
99
99
10
95
93
83
97
65
37
100
100
96
flos-aquae
-------
150
Table 45. Distribution of indicator diatom species in the western
basin of Lake Erie. The classification scheme of Tarapchak and Stoermer
(1976) was utilized. Only diatoms contributing 5% or more of the
biomass for a cruise are classified. M. = mesotrophic but intolerant of
nutrient enrichment* M_ = mesotrophic and tolerant of moderate nutrient
enrichment, E = eutropnic. 1970 data are from Munawar and Munawar
(1976). 1978 data are from Devault and Rockwell (1986).
M2 E
1970 0 1 5 0.2
1978 0 3 3 1.0
1983 1 2 3 1.0
1984 3 2 2 2.5
-------
161
Table 46. Trophic status of the western, central and eastern basins
of Lake Erie in 1970 and 1983/84. The classification scheme of Munawar
and Munawar (1982) is used. 1970 data is from Munawar and Munawar
(1982). Based on average biomass of basins in 1983 and 1984.
1970 1983 + 84
Eastern Basin mesoeutrophic oligotrophic
Central Basin mesoeutrophic mesotrophic
Western Basin eutrophic mesotrophic
-------
162
Table 47. Relative abundance of zooplankton in Lake Erie.
Rotifera
Cladocera
Copepoda nauplii
Cyclopoida
Calanoida
Harpacticoida
Amphipoda
Percent Percent
Bjomass Abundance
1983 1984 1983 1984
N
0
T
C
A
L
C
U
L
A
T
E
D
13
40
12
17
16
<
<
.6
.5
.3
.1
.5
.1
.1
69
6
15
5
3
<
0
.2
.0
.8
.4
.7
.1
.0
80
3
10
3
2
<
<
.1
.2
.4
.9
.5
.1
.1
-------
163
TABLE 48. Summary of common zooplankton species occurrence in Lake
Erie during 1984. Values are from the short zooplankton hauls only.
Species were arbitrarily classified as common if they accounted for
>0.1% of the total abundance or 1.0% of the total biomass, with the
exception of rotifers. Rotifer species were considered common if they
accounted for >1.0% of the total abundance.
Taxon
COPEPODA
Copepoda - nauplii
Cyclopoida
Cyclopoid - copepodite
Cyclops bicuspidatus
thomasi
Mesocyclops - copepodite
Mesocyclops edax
Tropocyclops prasinus
mexicanus
Calanoida
Diaptomus - copepodite
Diaptomus oregonensis
CLADOCERA
Bosmina longirostris
Chydorus sphaericus
Daphnia galaeta mendotae
Daphnia pulicaria
Daphnia retrocurva
Eubosmina coregoni
Holopedium gibberum
Leptodora kindtii
ROTIFERA
Ascomorpha ovalis
Asplanchna priodonta
Brachionus sp.
Conochilus unicornis
Keratella cochlearis
Keratella crassa
Keratella earlinae
Notholca foliacea
Notholca laurentiae
Notholca squamula
Polyarthra dolichoptera
Polyarthra major
Polyarthra remata
Polyarthra vulgaris
Synchaeta sp.
Maximum Average % of
Density Density Total
#/m #/m Density
Mean % of
Biomass Total
ug/m Biomass
79012
13367
4519
6311
3095
1407
20178
7731
4772
6675
21410
3752
6903
11215
807
623
57498
52038
157414
57762
40170
37236
42931
56316
93031
348455
61171
102788
18399
340262
340262
16275
3625
790
954
413
234
2652
890
TOTAL
710
157
1932
492
287
1209
63
35
TOTAL
6159
1806
3418
3404
7726
1575
1831
2825
5125
17392
4430
7768
2537
35357
14864
TOTAL
10.35
2.31
.50
.61
.26
.15
1.69
.57
16.44
.45
.10
1.23
.31
.18
.77
.04
.02
3.11
3.92
1.15
2.17
2.17
4.91
1.00
1.16
1.80
3.26
11.06
2.82
4.94
1.61
22.49
9.46
73.93
93.48
6510
2614
3637
758
1608
255
4249
3631
832
126
7506
7784
982
2417
754
627
77
1582
203
37
29
77
65
74
363
347
208
711
44
1597
1115
12.34
4.95
6.89
1.44
3.05
.48
8.05
6.88
44.08
1.58
.24
14.22
14.75
1.86
4.58
1.43
1.19
39.85
.15
3.00
.38
.07
.06
.15
.12
.14
.69
.66
.39
1.35
.08
3.03
2.11
12.37
96.30
-------
164
TABLE 49. Occurrence of eutrophic zoqplankton indicator species in
Lake Erie. 1984. Values are in number/tn .
BASIN
Western Central Eastern
Brachionus angularis 177 0 0
B. budapestinen* 92 0 0
B. calyciflorus 97 0 0
B. caudatus 81 0 0
Filinia longiseta 459 2.8 0
Keratella cochlearis f. tecta 2062 9.2 0
Trichocerca cylindrica 397 0 0
T. elongata* 907 0 0
T. multicrinis 477 42 0
T. pusilla 36 0 0
*Not listed as eutrophic species by Gannon and Stemberger (1978).
-------
165
TABLE 50. Ratio of calanoids to cladocerans plus cyclopoids in Lake
Erie, 1983 and 1984.
WESTERN CENTRAL EASTERN MEAN
BASIN BASIN BASIN
1983 0.19 0.31 0.45 0.32
1984 0.27 0.42 0.36 0.35
-------
166
Table 51. Correlation (r) of phytoplankton abundance with total phosphorus
concentration and zooplankton abundance within individual cruises (11 stations)
in Lake Erie, 1984. N.0.=not observed.
4/18-19
5/1-2
8/5-6
8/19-20
12/4-5
Daphnia
pulicaria
N.O.
N.O.
-.509
-.548
N.O.
Daphnia
spp.
.535
-.941
-.079
.061
-.448
Rot if era
.714
-.771
.021
.929
.097
Calanoida
.343
-.922
-.534
-.383
-.345
Tota
Phospho
.801
-.811
.756
.910
.505
-------
167
Table 52. Turbidity levels in 1978 and 1984,
Lake Erie. 1978 values represent graphical
accuracy.
1978 1984
mean±S.E. mean±S.E.
Western 4.2+1.5 2.66±.43
Central 0.7 0.40+.04
Eastern 0.5 0.52+.09
-------
168
Station Locations
Lake Michigan - Main Lake
Manistique
Traverse City
34 A Michigan
Ludington
Petosky
Milwaukee
<
Racine
Waukegon[
Chicago
Muskegon
Benton Harbor
FIGURE 1. Lake Michigan plankton sampling stations, 1984-85
-------
Lake Huron
Main Lake
Sampling Locations
CTv
FIGURE 2. Lake Huron plankton sampling stations, 1984-85. >
-------
Lake Erie
Main Lake Sampling Station
Lake Ontario
A
N
Michigan
Erie New York
Pennsylvania
Cleveland
Ohio
United States
FIGURE 3. Lake Erie plankton sampling stations, 1984-85.
-------
2T
o
a
o
LU
u
40-
30-
20-
10--
LAKE MICHIGAN
o Total
Total minus
picoplankton
AMJJASONOJF
E
X
E
0--
LAKE MICHIGAN
B
—-er*"- o
AMJJASONDJF
FIGURE 4. Seasonal phytoplankton abundance (Aa) and biovolume (4b)
trends in Lake Michigan* 1984-8^.
-------
172
.8-
01
5 .Bn
r— 1
0
o
•rl
CD
4-
C« *T
O
••H
i.
o
a.
o p-
c • *
Q.
0-
\J
_^_ LAKE MICHIGAN
"^"A __^*
\r~~~~~~~
•— — • BAC »
* « CRY
B— —c PIC
0 e CYA
0 — 0 UNI
« « COL
•— — • CHR
B— — a PYR
•—- -— » CHL x
. —-^-^^ ~-~~"~~~~~
p;;^:."^i^]^=;^^fe=s=s=s==:..s5Jg|
1 1 t 1 i — 1 1 1 i
M
J
0
N D
FIGURE 5. Seasonal distribution of algal divisions in Lake Michigan,
Bac=Bacillariophyta, Chl=Chlorophyta, Chr=Chrysophyta» Col=colorless
flagellates, Cry=Cryptophyta, Cya=Cyanophyta, Pic=picoplankton,
Pyr=Pyrrhophyta, Uni=unidentified flagellates, 1984-85.
-------
NUMBER/ML
NUMBER/ML
NUMBER/ML
NUMBER/ML
14
O
CO
O
O
H-
00
03
o
-------
NUMBER/ML
NUMBER/ML
O t-i
n o
a
CO 50
PI
?
05
05
n>
* s
*
O O
p n-
ito H
O H-
3" o-
C
T> rt
-t I—
— O
o
D Mi
1 »
•0 •— '
D>
3
i b
n
D
3 cr1
Si v-x
NUMBER/ML
NUMBER/ML
O IV) *•
t * * '
X
t-t
«-.
3^
0
2
D
(_i
•n
^v.
^v.
J*
m
*
t
\
\
jt
/
I
f
j
cn oo o IV)
i i i i
X
n
X
TJ
0
3
O
3
O
~fD
i
o
Q
^
O
T
3
n
a
-------
•*)
I
90
M
NUMBER/ML
oo
to
3
-------
Cyclotella ocellata
N -•» S
Dictyosphaerium
N
Qocystis submarina
N
I
B
Oscillator!a minima
N -
FIGURE 9. Seasonal and geographical distribution of a) Cyclotella
ocellata. b) Oocystis SMbTMJJLat °) Dictyosphaerium ehrenbergiamim and d)
. ^inj^na , Lake Michigan
-------
CELLS XI000 / ML
40
11
177
60
+ Total
o Non-picoplanKton
x Picoplanhton
Temperature
19 20 21 22 23 24 25
TEMPERATURE <°C )
CELLS XI000 / ML
0123
a.
10-
15-
20 A
CELLS / ML
120 160
comensl* - all vor.
o A. formoBa
x F. crotoneneiB
FIGURE 10. Vertical distribution of phytoplankton at Station A7. 15 August
1984, Lake Michigan
-------
X
Q.
a.
LU
o
10-
20- c
30 -L
10-
X 20- i
30-
40-
178
CELLS XI000 / ML
20
40
—H-
60
o non -
picoplankton
x Total cells
CELLS XI000 / ML
2
•H
o Baci1lariophyta
x Chrysophyta
* Chlorophyta
^ Cryptophyta
D Cyanophyta
• Temperature
B
21
22
23
24
25
TEMPERATURE C C )
FIGURE tl. Vertical distribution of phytoplankton at Station 18. 15 August
1984 , Lake Michigan
-------
179
o
o
o
r—I
X
CO
u
LJ
u
40-r
30-
20-
10-
0
1.6
* 1.2
\
o
o
o
1—I
x .8--
. 4--
1 \
LAKE MICHIGAN
o Total
y. Picoplankton
•+• Non-pi cop lankton
_, 1 > i
NORTH
A
-i , ,_
SOUTH
-i t i
A
I
CYA
CHL
BAG
CRY
CHR
\
•i • t
77 64 57 47 41 34 27 23 18 11 06
STATION
FIGURE 12. Annual geographical distribution of major algal divisions
in Lake Michigan. Bac=Bacillariophyta. Chl=Chlorophytai
Chr=Chrysophyta, Cry=Cryptophyta, Cya=Cyanophyta» Pic=picoplankton,
Pytspyrrhophyta, 1984-85.
-------
180
Z
N
O
D
O
X
(/>
LU
U
_j
o
o
o
X
1/1
111
(J
60-r
40--
20--
40
30--
20--
10--
40"
^ 30--
o
o
a
x 20-•
S 10
LAKE MICHIGAN
H
April 0-12
May 6-7
Ma*. 27-29
tec. 13 - IB
r
NORTH
I
""«
SOUTH
o Abundance
x Temperature
--4
--3
--2
if)
•-*
10
_j
LU
U
77 64 57 47 41 34 27 23 18 11 06
STATION
FIGURE 13. Geographical distribution of phytoplankton abundance on
all cruises, Lake Michigan, 1984-85.
-------
10-r
o
a
o
^-t
x
tn
6--
4--
LU
u
0
1960 1965 1970 1975 1980 1985
FIGURE 14. Historical abundance of phytoplankton in Lake Michigan.
Horizontal bars are the mean. Wide vertical lines are the standard error.
Thin vertical lines are the range. Data are from Stoermer and Kopczynska
(1967a and b). Rockwell et al. (1980), Makarewicz (1987) and this study.
CO
-------
182
0>
E
X
a
o
o
en
D
n
O
O
0
•—I
X
111
u
z
Q
z
ID
m
lOO-i
80-
60-
40-
20-
175:
140-
105-
70-
35-
0-
i_nr\c. muniuniN
/\
1 \
1 \
j \
1 ®L
// X
/ X.s^
- A
t \
/ \
/ \
/ \
/ \
/ \
/ \
°^ ^0
AMJJASONDJF
FIGURE 15. Seasonal zooplankton abundance in Lake Michigan, 1984,
-------
183
m
Z
0
O
o
\BUNDANCE XI
25-
20-
15-
10-
5-
120:
100-
80-
60-
40-
20-
0-
i r \ i \ i_ ii * ^^ i • * •«• • • • ••
L A o Calonoldo
. v x Clodocara
' \ * Copapoda
/ 4i a Cyelapotda
// \
/ A ^\
r's/'\Z^
' . Rot If or a
/ \
/ \
/ \
/ ^
/ \
*-** \
< . . , , . — : — . . . . .
MJJASONDJ
FIGURE 16. Seasonal fluctuation (numerical) of zooplankton groups in Lake
Michigan, 1984. Copepoda refers to the nauplius stage of the Copepoda.
-------
184
PI
2
o
o
o
X
07
3
20-
16-
12-
8-
4-
60:
45-
30-
15-
0-
I_/\r\L_ n x u*i i x uf \m
e Copopoda
f\ x Cyclopolda
/ \ * Rotlfwra
/ \
/ \
/ /^^^^
fs^ "^ ^
'&-*< ^ ^^*\
/ . o Colanoida
/ * x Cladocara
- / V
/ Q \
/ /\ \
/ s' V- ^
&-*f V_
•»-? , , , ,
AMJJASONDJF
FIGURE 17. Seasonal fluctuation (biomass) of zooplankton groups in Lake
Michigan. 1984. Copepoda refers to the nauplius stage of the Copepoda.
-------
185
16--
12--
-------
186 ,
LAKE MICHIGAN
tn
^C*
2
O
o
o
f- 1
X
en
50-
40-
30-
20-
10-
30:
24-
18-
12-
6-
VM. r * i « i,^. 1 1 ab ^^ 1 1 A ^^ f * 1 V
Total
/r~ -K A\
^^v X / v/A
V \
\
\
fe
o Colanoida
x C 1 adocero
* Copepoda
O Cyclopoido . \ O
O Rotifsro A ' \ /
/ ' \
^~^^ \ / V \
/^v-^r'"^ VN
- ^-/ ^X^"^ ^^ ^
N^ ^ \fZ- •*— >= *= ^ »
$ — -v — -_^_ ._ o _. ^^___ y
it i i i , ... i + i t i i I
77 64 57 47 41 34 27 23 18 11 06
STATION
FIGURE 19. Geographical distribution (biomass) of major zooplankton
groups in Lake Michigan, 1984. Copepoda = Copepoda nauplius.
-------
LAKE MICHIGAN
CE
LU
L_
l
1— 1
_J
a:
Ld
CD
2:
Z)
~z.
61
5-
4-
3-
2-
1-
0-
H»
o Diaptomus
sici 1 if
x Diaptomus -
" A
. ^ / V
. ^w
0
o e — •"
77 64 57 47
K
5 / \
copcpodite / \
/ \
/ i
/ \
i \
/ \
f \
X / \
v \
X
^^ _ —CXa^fVi—. .. _ JJI^Up"^^** " ^^^ T»y^^*^ _ ^_*^
Q — --"^r '^•"•'J i***^— *^J
l 1 1 1 1 1 1 1
41 34 27 23 18 11 06
STATION
FIGURE 20. Geographical distribution of Diaptomus sicilis in Lake
Michigan, 1984.
CO
-------
o:
UJ
HH
_J
\
(T
UJ
m
Z)
6-1
5-
4-
3-
2-
1-
o-
§•
^ LAKE MICHIGAN
\
'F o Eubosmina corQgoni
\ x Bosmina longirostris
\ + HolopQdium gibborum
\ a Conochilus unicornis
&-!._„
' \ ^\
' S \ \
\ \
- \ \ \ __
^=--*=:4t=:^-a^84^=:S^:*=:S^.^
77 64 57 47 41 34 27 23 18 11 06
STATION
FIGURE 21. Geographical distribution of selected zooplankton in Lake
Michigan, 1984.
oo
oo
-------
LAKE MICHIGAN
o:
UJ
i—
i— *
_j
\
NUMBER ,
141
12-
10-
8-
6-
4-
2-
0-
r o Notholca foliacea
x N. laurentiaQ
R * N. squamula
\ f\ O Polyarthra vulgar is
/ \ Q P. romata
' / \\\ ^*--
/ A \^ \ »
rt \ \ ^\ ^DtL \X' L/' /'
^> — — -\or ^*^\**&~^ ^6^ -£* -
&—- -s^^'!*^3*^'5^^^^^-^
*j~— --^^- Q O — Q =BI — :--€3
. 1 • • 1 1 1 1 1 i i A
77 64 57 47 41 34 27 23 18 11 06
STATION
FIGURE 22. Geographical distributin of selected zooplankton in Lake
Michigan, 1984.
oo
-------
1
— 1
O")
D
to
0
E
O
•fH
GQ
1DU-
120-
90-
60-
30-
0-
•*
LAKE MICHI
••
H
/ \
/ \
7 \
^8^ 8
o 100m Stati
x 40m Stati
CAN o
/\
/ i Total
\
/ \
. \
\ f *^^^^
\ f ^*
-4 V A
; \
on / \
on / \
© Lakawtda offshore avaragQ / Daphnia
& — e — ®— --e---'s*-^Q^ spp.
I 1 1 1 i i —4 1 1 1 « 1
1975
1980
1985
Figure 23. Historical trends in zooplankton biomass during July and
Augusts Lake Michigan. The 1984 data point represents the mean of all
offshore stations. Modified from Scavia et al. (1986).
VD
O
-------
LAKE HURON
E
X
t!
AMJJASONDJF
40 T
30--
-I
\
o
o
o
x 20--
ui
u
10--
LAKE HURON
B
o Total
Total minus
pi cop lank ton
AMJJASONDJF
FIGURE 24. Seasonal phytoplankton biovolume (4a) and abundance (4b)
trends in Lake Huron, 1984-1985.
-------
Proportion Biovoluma
M o 35 ij
*O M C M
00 "•< H Q
*• II O C ->,.
1 0 3 » •>*
• t3 fO
ll9" ^
ft OS (&
co n co
"MO <__!
O M 3 '
^s CD Co
co H M
II H-
000.
co tr m' (— i
3 VJ rt
Ort H
«T •»
^ (D H.
^" c _
rt Q f+ ^>
0> cr H-
"MO
1^ m
H» O M
O >O 00
O B* ts
•O "^ M <—%
M ft CD
CD 0 «-x
if" ^
o tr H-
3 H O ~7
• II I J
n sr o.
H *^ (-U '
&• rt o- #
\ X /
\ /
\ /
1 1 "\S
• \ i ! \ / / m
\|M / E
'K! > \ / |
f\/ x\ /
ft \ L
k / ^
Ji I i
\ / /
1 / /
JL w J[
' \ ^s,
X \ ^
40 x «
R-
n>
Z6L
-------
193
10 -
61 5*4 45 37 32 27 15
STATION
FIGURE 26. Annual geographical distribution of major algal division in
Lake Huron. Bac=Bacillariophyta. Chl=ChlorophytaB Chr=Chrysophyta,
Cry=Cryptophyta» Cya=Cyanophyta, Pyr=Pyrrhophyta, 1983.
-------
o
V)
u
\
o
o
o
«—I
X
(ft
LU
CJ
30-r
20--
10-
1.2-
194
LAKE HURON
NORTH
\
\,
A
/
\
o TOTAL
x PIC
-> SOUTH
-»-
BAC
CRY
CHL
CYA
CHR
\ /
/
61 54 45 37 32 27 12 09 06
STATION
FIGURE 27. Annual geographical distribution of major algal divisions in
Lake Huron. Bac=Bacillariophyta. Chl=Chlorophyta, Chr=Chrysophyta,
Cry=Cryptophyta, Cya=Cyanophyta, Pic=picoplankton, Pyr=Pyrrhophyta.
1984-85.
-------
195
/u-
_l
z- 50-
o
o
o
x 30-
Ul
u
10-
_i 30-
X
o
o
2 20-
X
i/)
u 10-
o Jui s - 7 LAKE HURON
* Aug 3-4
* Aug 10 - 12
• Aug 17 - 16
D Nov 27 - Dec 2
B
«^^ ^^V^ *"*""' - *
"""•* ^lH -/ ^^\^
1 1 1 1 1 1 1 1 1 1
o Apr 12 - 15
x Hoy 4-5
* Dec 10 - 13 NUKIH " bUU 1 H
« Jan 15 - 16
a Fab Q - 10
A >
/ \ /^i ^«
/*^\J*^'^ /S*^*^/
t t 1 : 1 1| 1 < 1 1 1
61 54 45 37 32 27 12 09 06
STATION
FIGURE 28. Geographical distribution of phytoplankton abundance on all
cruises. Lake Huron, 1984-85.
-------
NUMBER/ML
NUMBER/ML
so *n
n- M
D O
M
I?
O
C 3!
M fB
IB
•a CD
-i. m
13 Qj
CO
to O
3
Q.
Oi
a-
3 C
D ft
Q- h1-
-• O
en 3
O
C O
CO hh
B to
-1. V^
3
O
CO
•O a*
Pi
?r
(B
l-t
O
3
O
z
o
n
n
o
i—»
•o
D
(-1
00
•- N U>
O O O
O O O
H 1 h
•+•
o
o
H
0
M
0
r»-
0
n
li-
ft
U)
o
0
NUMBER/ML
NUMBER/ML
96 L
-------
o
M
w
o
3
re
en
(D
OJ
CO
O
3
03
O.
H-
tn
rr
cr
O
3
O
P
tn
n
NUMBER/ML
a
o
0)
o
-H
O)
o
(O
o
ro
o
H
t/)
O
z
a
o
0
o
o
c*
0
*«•
o
3
I*
3
M>
3
O
B-
ro
O
3
Z6L
-------
198
CELLS XI000 / ML
I
a.
UJ
a
w 15
20
25
o Total
> x Picoplankton
•*• non-pi cop 1 ankt on
5..
10--
0.
g 15
20
25
CELLS/ML
40
—i—
80
—i—
o Cyclotolla ocellata
x C. kuotzingiana v.
pianetophora
120
i
10
15
i
20
°C
FIGURE 31. Vertical distribution of phytoplankton at Station 37, 15
August 1984, Lake Huron
i
25
-------
199
CELLS XI000 / ML
10 20 30
40
~ 10-
fc 20
D
30-•
\
\
CELLS / ML
200 400 BOD
10
£j 20 +
D
T /
f
H.H
IV \
IA \
o Boeilloriephyta
x Cyclotollo cOMnsIs
* C. oral lota
• Totallarla flocculate
j\
30-• * V
400 BOO 1200 1600
I
a.
10--
SO--
SO-
\ o Chryoophytq
/ x Dinebryon oociol*
* 0. dlvwganc
FIGURE 32. Vertical distribution of phytoplankton at Station 15, 15
August 1984* Lake Huron
-------
m
LD
2-r
1. 5-
0-
19
•
70
1974
1978
1982
1986
FIGURE 33. Historical offshore biomass trends in Lake Huron. Values are
the mean±S.E. and the range. Data are from Munawar and Munawar (1979),
Makarewicz (1987) and this study. 1980 offshore data are modified from a
GLNPO data base.
ro
o
o
-------
201
o
X
O
o
D
«— i
"X
CD
PI
X
o
a
o
LU
o
a
CD
60-
45-
30-
15-
•
150-
125-
100-
75-
50-
25-
0-
LAKE HURON A
A
' ®v
/ ^x
f \^
/ \
/ \
/ N*
' d
B
/ \
/ \
/ ^
/ x.
- /
d ^&**
~. III! < « 1 1 1 1
AMJJASONDJF
FIGURE 34. Seasonal zooplankton biomass (a) and abundance (b) in Lake
Huron, 1984.
-------
202
CD
X
O
o
o
><
UJ
L)
Q
z
m
20 -r
16-
12-
Q.
4-
100-
BO
60
40
20
0
LAKE HUKUN A
Q o Calonolda
/ \ x Cladoesra
IB A
^r*^ *^^» f
*— A \ a Cyelopolda
/ >^V_ \ >
/ A* v-V^
/ / x
/ <^*\ "~~" "-^ to
(/ / /^ >*^^. *~13*3
./ s* — • ' — — u M
B
*
/ \
/ • Rot if era
/ \
/ ^x
/ X\
/ X
' , ,,4 1 ..II • ' ' _ «
MJ
SONDJF
FIGURE 35. Seasonal fluctuation (numerical) of zooplankton groups in Lake
Huron, 1984. Copepoda refer to the nauplius stage of the Copepoda.
-------
203
m
X
| xlQQQ
O7
30 -]
24-
18-
12-
6-
»:
12-
9-
6-
3-
0-
LAKE HURON A
o Caionolda
H C 1 OQOC QT*Q
\
y^^V-^^
• -/ \
/ w
B
o Copapoda
x Cyclopolda
* Rot 1 fora
/ \
G— - ^f_ *
7^ Q KV.
AMJJASONDJF
FIGURE 36 . Seasonal fluctuation (biomass) of zooplankton groups in Lake
Huron 1984. Copepoda refers to the nauplius stage of the Copepoda.
-------
i -
Q£ p
LU ' °
•
I —
i— »
-1 . 6-
x
o:
LJJ . 4-
m
ID
^- . 2-
0-
LAKE HURON
» ^^ i
Daphnia pulicaria ' \
/ \
- o 1984 / \
x 1983 / x
1
1
l
I
NORTH ^* l SOUTH
^ N/ A
/ \
61 54 45 37 32 27 12 09 06
STATION
FIGURE 37 . Geographical distribution of Daphnia pulicaria in 1983 and
ro
o
1984, Lake Huron.
-------
205
pi
o
o
o
X
UJ
u
<
o
D
CD
12-
9-
6-
3-
80 :
60-
40-
i
20-
0-
f LAKE HURON ° coionoida A
. x Clodocera
/ \ *• Copapoda
4l jS \ D Cyclopoida
\ ^C \ R^ f
^ Ne--^l \~t***$
' * ^
^^-fr^^^^^S*
j^^ M
-^| H~- -*~- "^ ^^ -^K>^ ^^ _ H
jra o Total B
• J^^"^^*^
* '
-------
206
o>
O
O
O
X
a?
D'
35-
28-
21-
14-
7-
15-
12-
9-
6-
3-
0-
LAKt HUKUN
o- ^^ A 7°
"^e^ \ / \ /
V v
Total
D Cyclopoida o Calanolda /
O Rot if era x Cladocera /
Qi * Copapoda ,
/ \ /^ '
XQ— ""Q. / \ y
/ w O
" ^x ^/N\e('/ \
-*0" ^<-^ ^ V^~~K
. s--*-^ ^.^-^.^^
. i 1 1 1 i i 1 1 *
61 54 45 37 32 27 12 09 06
STATION
FIGURE 39. Geographical distribution (biomass) of major zooplankton
groups in Lake Huron, 1984. Copepoda refers to the nauplius stage of the
Copepoda.
-------
207
10
.£
O
O
O
x
CO
CO
O
cr
o
12
8
6
5
4-
3
2
I
30
20
10
LAKE HURON
CALANOIDA •-
NORTH
CLADOCERA »-
CYC LOP DID A, •-
NAUPLII
I J i i I J I I
TOTAL •-
SOUTH
I i i r r i i ITT
61 54 45 37 32 27 15 12 9 6
STATION
FIGURE 40. Geographical distribution of major zooplankton groups in
Lake Huron, 1983.
-------
208
CK
LU
•
1—
^^•^
_J
\
o:
NUMBE
o:
LU
L—
1
^^
\
LU
CD
2
61
5-
4-
3-
2-
1-
i I
. 8-
. 6-
. 4-
. 2-
0-
r LAKE HURON
o Not ho lea squamula ,x^ .
x Polyarthra vulgar is ,r
+ Synchaota sp. /
/
/
/
A ' /
* — ""N //^\ /
' X"" \ / V v
x \/ « * — *
x \y ^13 *^
• • ' • i t > i t i
o Diaptomus sicilis 8
x Mosocyclops odax ?>•» Xn
-•• M. - copopodito / v^ 1
\ !
/ /
& s^.% .— e-^'*^6^. /
- ^ '7' "^" •' ^/
/
^ 1
,***<'-~X^l ^ _K
1 ^ 1 1 1 Mi 1 1 1 1 1
61 54 45 37 32 27 12 09 06
STATION
FIGURE 41 . Geographical distribution of selected Rotifera (a) and
Copepoda (b) in Lake Huron, 1984.
-------
209
goo
j 800-
X
1* 700'
O
- 600-
*~~
in
500
I I
• Hs4
r «\
1 i
^ ^-^
\s ^
61 54 45 37 32 27 12 09 06
. 4-
a
4J
L ^
^ -~
Z X
* JP. 3-
2
D
L
4J
Z
16-
^, 14-
u
o
~ 12H
o
L
3 10-
o
i, 8-
D.
E
0 _
i- 6-
1 O
la '
18-
3
X
I1 17-
o
- 16-
U-
w 15-
14-
r 7'
6-
w
^
o 3
I 1 ^i A_ DO)5'
1 ^"^-V'l '~-i IT $ 0.3
i--'T y T w
r ^ 4'
"o ^'
o
i i r ' *^
V, y'
> i 1 '
2-
>
/
, f ,
$6.5-
k i7
\
V-* -8 61
K/*^--t — *" c
£5'5'
. — . , I S-
jr-"
A /
AH
w i *!* --»— • m
1 '
f
.-f^. 1
i v ^Y
^•^^
i
61 54 45 37 33 27 12 09 06
61 54 45 37 32 27 12 09 06
Figure 42. Water chemistry along the north-south axis of Lake Huron,
1984. Values are the station mean ± S.E.
-------
cc
LU
Of
UJ
GQ
20--
15--
10-
5-
0-
LAKE HURON
f
,,
CrustacQa
(Qxcluding nauplii)
—i—
1970
1975
1980
1985
Figure 43. Crustacean abundance (excluding nauplii) of Lake Huron,
1970-1984. 1970:Watson and Carpenter (1974). 1974:McNaught
(1980), 1983:Makarewicz (1987). 1974 data represent
offshore sites only (Areas 9 and 10). Values are the mean ± S.E.
ro
—j
o
-------
a:
UJ
*~~
_j
\
or
LU
luifcj
m
Z)
^
300-
•
250-
200-
150-
100-
50-
0-
R LAKE HURON
1 i
/\
.' \ o 1974
1 \
1 i
I \ + 1983
i \
* ii
• •
/ \ x 1984
i i
•' \
/ \ RotifQra
\
1 ,
\
x 4 * \
/* \ b Q^
' &-'*-- * *^"^-^. ^°
i 1 — « 1 i i 1 1 i » > i
M J J
S 0 N D J
Figure 44. Abundance of Rotifera in Lake Huron in 1974, 1983 and 1984. 1974
data are from offshore stations only (Stemberger et a]. 1979).
ro
-------
212
a
o
o
?-*
x
U)
UJ
u
100T
80
60
40
20
LAKE ERIE
o Total
x Total minus
picoplanKton
AMJJASONDJF
2T
1. 5--
E
X
E
E
U
U
.5--
B
ai \
^
J
\
o-i—>
AMJJASONDJF
FIGURE 45. Seasonal phytoplankton abundance (a) and biovolume (b) trends
in Lake Erie, 1984-85.
-------
PERCENT BIOVOLUME
O W Ml
*< to M
to o O
11 ii <=3
o w ^o
to n ..
3 p- z
O t--1 w)
CT to
to o ID
D* 01
hd V! O
P- rt 3
o to to
II • t->
p- o a.
O 3" P-
O P4 0)
•O II rt
p* O >•!
to 3" P-
3 p* cr
7f O C
rt ^ rt
OOP-
CJ ^3 O
. a- 3
htf rt o
i to
TJ O (-•
V! n" 00
H H to
H II p-
o ff a.
•O H P-
v; to p-
rt O to
to *o p*
• 3" O
*
i-t
rt p.
O (B
•O •
rr
• n n o n a»
- -< so I -< I >
n so -< Jo > r n
1
-------
214
90-
70-
50-
30-
N.
o 5"
O
0
X 3-
LO
_J
_J
LU I"
U
. 8-
.4-
0-
^ LAKE ERIE
v\
\x o TOTAL
\\x PIC
\\
^ ^^
* o BAC
\ * CYA
\
\
\ *
a ^ \
VAX ^-^
o CHL
* CHR
• o \
\ »<^
V^ ^^"\^
\j r~ c T , - r~ A c T
WLo 1 tAo 1
60 57 55 42 73 37 78 79 18 15 09
STATIONS
FIGURE 47. Annual geographical distribution of major algal divisions in
Lake Erie. Bac=Bacillariophyta, Chl=Chlorophyta» Chr=Chrysophyta»
Cry=Cryptophyta» Cya=Cyanophyta, Pic=Picoplankton, 1984-85.
-------
400
* 300
O
O
5 20°
UJ
u
.. \
e April 18-18
x April 20-21
1- 2
2- 3
LAKE ERIE
60 57 55 42 73 37 78 79 18 15 09
75T
o Aug. 5-6
K Aug. 7-9
g
1 55-
O
X
w 35-
_i
UJ
u
15-
\
Ok
&=*• 4fZ
mf
* Aug. 19-20
j/£—^f**\^
^S ^>* -^ • — *
75T
55--
o
o
o
x 35
tn
UJ
u 15
60 57 55 42 73 37 78 79 IB 15 09
e 0«c. 4-5 C
K D«c. 5-9
A
\
\\ s
» Jon. 13-14 19BS
V
V
N
60 57 55 42 73 37 78 79 18 15 09
STATION
215
FIGURE 48'. Geographical distribution of phytoplankton abundance on all
cruises, Lake Erie, 1984-85.
-------
216
300 T
° A»t«rlon«lla formoBa
x Frog 11 or la crotoncnsii
+ M«lo«lra ialandica
A
tn
UJ
150-
75-
0-
200-1
' ' ' \ -y\
^ v u.v/ v.
®^^^ i ^^^^fc_
o Staphonod i «cu» *p.
tn
150--
100--
x Podiastrum simplax v.
duodanar i urn
» Chroomonas normtadti i
_J
UJ
" 50-
0-
600-1
V^ ;
/ \\^^^^J-^^ ^
\ ^~-^-*~*~
t i^^^ «^*«^^ •^•••••B ^U«^B «^^^_ ^M>^^ ^M««m .^ri_^ -"
** ™ -» — ^^p~^— ™^r^^~ ^w^^ ^W*«"» "^F^^ •
-------
217
3500-
2800-
X2100-
if)
j 1400-
ai
u
700-
0-
80 n
' *
^ Anocyctic Montana v. Minor
\
\
\
\
*^^ /A,
^-^^ v-*-^-*
A
^ 60 +
o
a
2 40 +
x
to
d 20 +
LL)
U
0
1200
\
\
\
\
in
900--
600-•
_
U)
u 300
0--
o RhodoMonas •loota v. narmoplanktica
x Oscillatoria limnatlca
* Marismopadia tanuiealaa
60 57 55 42 73 37 78 79 18 15 09
FIGURE 50. Geographical distribution of selected species, Lake Erie,
1984-85.
-------
NUMBER/ML
NUMBER/ML
o
>
3Z
l^
u
S "n
O c|
to ya
-•• M
51
M^ O
35 "3»
zl *^
Qu 03 ^y
H- 3 *-
(•}
Pi en
" £ o
O CO
*~ ' O
> Co
3 »-«
a- a. _
a> H- I
T) CO
?X
di
T
U
( i
i.
3 rf *
H-
co cj*
*X3 C
• rt
H-
Co o
O
£"« 0
03
CJ ^^ '
-t ^_
C to- •*
n »
->• rf
IQ t
ro -i Z
3 -••
— O
S3 3
T> *-•
-t ->
r^ — *
n »
T J" *-•
3 0
2 "*
-• 0
33 CO
h| |p3
J> * (/I
a4
• ^— *
IT- °
R-
« 2
M
•o' CJ
^
"n_
B
5
T
1
-
i
o
1
A~.
f'
i
\
•
i>
fc-.k-.rv) *- IM
ui o ui o a o
o a o o a a o
/'*~~~~~~ *
/ Z u,
fc-4
0 c,
a
**-
a >
• W
S °
w
a
o z
"
a
u*
00
-n
^s
^^^^ >
B*""*" *
/ O
n **"
f s
1 o
i =
\
> ?
, T
\ 3
% °
T •
1 o
I
n
\
\,
NUMBER/ML NUMBER/ML
IM *. 01 *- *- IM
O O OOOOOO
c —
n
**" ^^
(0
o
3 «-•
**•
— °
— " — TO T *
>•• x^ O
/ R w
X 0
*-^.e__
"~n"^"''=*<
X
X >
X 3
^^ o
^ QT
^ O
x-X S
_x o
II
•p
I
A
U)
a
o
S)
>
IM
Ul
O
D
O
-------
219
1983
f-01970
>I984
to
E
v.
o>
I*
o
CD
M
A ' S 0
MONTHS
N
FIGURE 52. Seasonal fluctuation of weighted mean phytoplankton biomass in
1970, 1983 and 1984, Lake Erie. 1970 data modified from Munawar and
Munawar (1976). 1983 data from Makarewicz (1987). Values are corrected by
using the weighting factors of 15.6%, 59.6% and 24.6% for the western,
central and eastern basins (after Munawar and Munawar 1976) .
-------
220
i<;-
9-
m
E 6-
\
OT
3-
n-
. o
"•*-••*.
LAKE ERIE
""'^-^.^
^^**" * *""*J
I
)
I
-
-
— i
1955 1965 1975 1985
FIGURE 53. Regression (r =79.2%) of phytoplankton biomass versus time in
western Lake Erie. Modifed from Gladish and Munawar (1980). 1956-58 data
are from the Bass Island region. 1970 data from Point Pelee and near the
mouth of Detroit River. 1975-76 data are from northern portions of the
western basin. 1978 data are from similar geographic areas as 1970
(Devault and Rockwell 1986). 1979 data are not included because of a
reduced sampling regime and other technical difficulties (Devault and
Rockwell 1986). 1983-84 data are from Stations 60, 57 and 55. Except for
the 1956 and the 1957-58 data sets, all enumeration was by the Utermohl
technique. In 1956 and 1957-58, a settling technique was used, but counts
were not made on an inverted microscope. Thin vertical lines are the range.
Wide vertical lines are the standard error.
-------
16-r
12-
JI <
CL
o
L
O
U
8-
0
LAKE ERIE
1970
o V/QstQrn
x CQntral
•*• Eastern
\
^
v
i i < < i ( < i t t ( i—i i >•
1975
1980
1985
Figure 54. Time trend in annual cruise mean concentration of
corrected chlorophyll a since 1970. Data from Rathke (1984) and this
study.
ro
ro
-------
Total phosphorous
(ug/L)
CD **J
j->. H*
3 00
o e
ro H
fD
£ (n
•-J Ol
0 .
•
§"•3
fD 3
* 0.
1 (-»•
>-i £
m »-•
i-h 0
3 H.
"^ &>
5, <*
° 2
» *
» S.
^ ^
rf
H- O
^
ai
OB m
CO
?
O.
rj -^ cn
o o o o
'••iii
i—*
co_
o
(D
VMV
(Jl
*-»
CO
CD '
0
i— »
CO
J ' 1 — — T 1
\*f P
/\ /
r ^'~~*tf
mA*""* \
^^" ^ cs i —
* T*.^ ^% L^
' X > -
£* ?
W / m
/, y ^
ff / «-•
j >« cs^ + x o rn
1 f > mn«
i * <2f Q (D (D
r /^ to 3 w
A x (^ ft ft ft
T f r ro T (D
1 / / -J Q -J
*X 0 3^3
co •"•
en
-------
223
m
2:
o
0
0
*•<
X
CTJ
^
n
s:
o
0
0
«— 4
X
UJ
u
a
2
CD
125-
100-
75-
50-
25-
300 :
250-
200-
150-
100-
50-
0-
r LAKE ERIE
_ A
—.^.Q ^
/ \
/ \
r \
/
/ \
/ \
' J \
/ X
O tf>
I ..........
Q n
/ ^^"^^ ^
• / ^
' \
i \
. ' \
/ \
-ti \
\
\ r
e
1 1 1 i < 1 1 . • • i
AMJJASONDJF
FIGURE 56. Seasonal zooplankton abundance and biomass in Lake Erie,
1984. Short hauls are plotted.
-------
224
^
1)
X
o
0
o
SUNDANCE C X]
16-
12-
8-
4-
0-
240-
200-
160-
120-
80-
40-
0-
A
LAKE ERIE ° J*1""01*'
x Clodocoro
A •*• Cyclopoido
/ tx^_
--/^ **" \ \~~ "~**
.Tf X\Xx«
X \
// \
ho Cop«podo B
\ \ * Rotifsro
/ ^v. ' \
1 ^^J \
• J " \ -
/ \
- / \
./
\
- ^ V
AMJJASONDJ
MONTHS
FIGURE 57. Seasonal abundance distribution of zooplankton groups in Lake
Erie* 1984. Copepoda refer to the nauplius stage of the Copepoda.
-------
225
q
2
o
o
o
f— 1
X
07
80 -i
,
60-
40-
20-
0-
LAKE LKit
o
X
/ \ *
/ \ °
/ \ D
i /„ \
s \
^^fri^^K^^ x
Col one Ida
Cladocara
Copepodo
Cyclopolda
Rot If era
\^
*
AMJJASONDJF
FIGURE 58. Seasonal biomass distribution of zooplankton groups in Lake
Eriet 1984. Copepoda refer to the nauplius stage of the Copepoda.
-------
226
O
O
O
111
u
z
<
O
z
•D
CD
LAKE ERIE
o Total
x Rot i fora
Total crustacQa
o Co1anaIda
x Clodocera
* Copapoda
Cyclopolda
60 57 55 42 73 37 78 79 18 15 09
STATION
FIGURE 59. Geographical distribution (numerical) of zooplankton groups in
Lake Erie, 1984. Copepoda refer to the nauplius stage of the Copepoda.
-------
227
ro
X
O
o
o
X.
D7
D
/D-
60-
45-
30-
15-
•
40-
30-
20-
10-
0-
L.AK\CL CLIMC. A
^ ^e-^ \ /
^-^^
Total
i
o uojanoiaa
x C 1 adocara *
* Copapoda /
^ D Cyclopoida /
. * — -K^ O RotifBPa /
\> ~~~~^ H-J
• \ Ax / 4
• ^>i^C^^J
: . . • • . — — . • • 1 • 1
60 57 55 42 73 37 78 79 18 15 09
STATION
FIGURE 60. Geographical distribution (biomass) of zooplankton groups,
1984. Copepoda refer to the nauplius stage of the Copepoda , Lake Erie
-------
228
a:
UJ
h-
f— 1
_J
or
UJ
CD
ID
z
Q,
UJ
H- 1
_J
tr
UJ
CD
ID
z
3j
2. 5-
2-
1. 5-
1-
. 5-
r
. 8-
. 6-
. 4-
. 2-
o-
o Cyclops bicuspidatus
thomasa
LAKE ERIE « x Diaptomus oregonensis
/' \ * Daphn i a pulicaria
\n Mesocy clops edax
/ \
/\
\
u
yltv
/y*&-.^' \ f
^^*^v x jt \ w / *S / ^v_.
L^ H ^» * ^VL \ « i *m / TQ
)j/ ! >s^—-i"'^^** v -e^^'^yC. ./ "//^
. *=.-.'%LU
a
o Ho 1 oped i urn gibberum
x Tropocyclops prasinus
mexicanus
/ \
/
^ -A /.A --
,«/' ^N^' Nt---*' y'/ ^^
60 57 55 42 73 37 78 79 18 15 09
STATION
FIGURE 61. Geographical distribution of selected Crustacea in Lake Erie,
1984.
-------
229
cr
UJ
i—
i — i
— i
o:
UJ
CO
2:
z
C£
UJ
h-
1— H
_)
\
o:
UJ
CD
Z)
z
iuu-
80-
60-
40-
20-
1r—
5-
12-
9
-
3
0
LAKE LKlt 0 Notholca foliacea
x N. laurentiae
3 ja * N. squamula
*T^/\i D Polyarthra vulgaris
°\ ^ o Synchaeta sp.
\ \\
i \» 1-1
v . \ R
^ \\ / \
\ /*V'x / V^'^
- ^£A\ '^"^-^-
. i 4 | 1 1 1 1 1 |
\ o Asplanchna priodonta
"TX x Keratella crassa
x_
\ \ + K. earlinae
1 \ n Polyarthra do li choptera
\\ \ oP. remata
•\ \
v 2\
V, 7\ s\ **.,
- J / \ J \ ^TI ,
1 ' \ / \ CU
\y *% X \ *T
*\\ /\X^^p*. *
/ \ ^t^ \ "^t \
/ \ /V\ \/^^-^/^--4^
i_ . • 1 1 1 — * — — • • ' ' — — • 1
60 57 55 42 73 37 78 79 18 15 09
STATION
FIGURE 62. Geographical distribution of selected Rotifera in Lake Erie,
1984.
-------
CC
LJ
LL!
CD
100T
80-
60--
40-
20-
0
LAKE ERIE
o Copepoda
x Cladocera
•*• Total Crustacea
? . _
—'—
1940
1960
1980
FIGURE 63. Crustacean zooplankton abundance since 1939 in the western
basin of Lake Erie. 1939 data are from Chandler (1940; April-October).
1949 data are from Bradshaw (1964; April-October). 1983 data are from
Makarewicz (1987; April-November) and 1984 (This study; April-December).
Values are the mean ± Standard Error.
ro
oo
o
-------
UJ
h-
I—»
_J
\
a:
LU
m
150-
120-
90-
60-
30-
n
LAKE bKIt
o CladocQra • \
' x Adult Copepoda / «
-«- Total Copopoda * / \
/ \ 1 \
/ V -
/ K \ '
• / i \ \_t
s ^f\ \\
^'- ^JEf v^ KO
°^1 , 1 — — . 1 . 1 ' 1 •
1940
1950 1960 1970
1980
FIGURE 64. July and August abundance of Cladocera and Copepoda in the
western basin of Lake Erie since 1939. Total Copepoda refers to adults
plus the nauplius stage. Data are from Chandler (1940), Bradshaw (1964),
Hubschman (1960), Britt et al. (1973), Davis (1969b) Makarewicz (1987) and
this study. The number of adults and total copepods in 1939 and 1959
follow Bradshaw's (1964) calculations.
ro
CO
-------
QL
Ul
•
r-
t— i
-J
^
o:
LU
m
«•_
2
240-
200-
160-
120-
80-
40-
P>
•
j\ + 1970
/ \ x 1983
• i
- i *
i %
/ \ o 1984
v
/ ^
/ V
' V
/ A
/ .
/ *3**~96^
| ^^0 \ ^^^^
*"fU0^" ... ^ .
A'MJJASONDJF
FIGURE 65. Seasonal fluctuation of weighted mean Crustacea (nauplii
excluded) abundance in 1970, 1983, 1984, Lake Erie. 1970 data follow
Watson and Carpenter (1974). 1983 data from Makarewicz (1987). 1983
and 1984 values are corrected by using the weighting factors of 15.6%,
59.6% and 24.6% for the western, central and eastern basins (after Munawar
and Munawar 1976).
tXJ
CO
-------
o:
UJ
i
i —
\
o:
LU
CD
Z)
720j A
600-
480-
360-
240-
120-
0-
J\
i v
I \
1 x
" i y
\\f
/
i /
• J/
i — i — i
LAKE ERIE
A
/ \
/ \
ff \
v/ \ o 1939
» \ x 1961
\ A D 1983
\ /X * 1984
\ • V x
\ / \\
\ .' \ \
\ \ \
\ 1 V \
V \ TX-
* XT \
/ \i \
/* u * *•
, , , 1 1 1 1 1 1
AMJJASONDJ
MONTHS
FIGURE 66. Seasonal fluctuation of Rotifera in the western basin of Lake
Erie from 1939 - 1983. Sources: 1939 - Chandler (1940); 1961 - Britt et
al. (1973); 1983 - Makarewicz (1987). The 1970 samples of Nalepa (1972)
are not included because they are from the far western end of the basin and
may not be represented of the entire basin.
ro
oo
co
-------
01
X
01
35 j
30-
25-
20-
15-
10-
j" •
0--
New York waters
Western basin
i
ji
1975
1980
1985
Figure 67. Abundance (millions of fish) of fishable walleye (age 2+)
in western Lake Erie (Ohio waters). For New York waters, values
represent catch per 22 net meters in variable mesh nets. Data from
Ohio Department of Natural Resources (1985) and New York State
Department of Environmental Conservation (1985).
oo
-------
a
o
a
L
O
X
auu-
600-
400-
200-
0-
»
Wai leye
m
1975 1980
1
\
— L»— 1
1985
Figure 68. Sport angler harvest of walleye from the central basin of
Lake Erie. Modified from the Ohio Department of Natural Resources.
ro
oo
en
-------
236
a
o
c
o
T)
c
3
JD
0
01
>
ri
4*
O
'a
or
3000-
2500-
2000-
1500-
1000-
500-
240-
200-
160-
120-
80-
40-
1500:
1200-
900-
600-
300-
0-
1 • M ew i f e
/\
I •
• / \ J(
\
' *• / \
• / \/ v
-------
25-r
20-
15-
10-
0--
LAKE ERIE
/A
\ \
Y\
o
X
18 April
19 August
4 DecQmbQr
V
-*
--x
-I I 1 1 I 1
60 57 55 42 73 37 78 79 18 15 09
STATION
Figure 70. Seasonal and geographical turbidity trends in Lake Erie,
1984.
ro
oo
-------
238
Table A
Phytoplankton
Species List: Lake Michigan
-------
239
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
bAC
Achnanthes af f ini s
Achnanthes bi aso 1 et t iana
Achnanthes clevei
Achnanthes clevei v. rostrata
Achnanthes conspicua
Achnanthes deflexa
Achnanthes ex igua
Achnanthes exigua v. constricta
Achnanthes f 1 exe 1 la
Achnanthes hatckiana
Achnanthes
Achnanthes
Achnanthes
Achnant hes
Achnanthes
Achnanthes
anceo la ta
anceo la ta v
apponica v.
apponica v.
i near i s
i near i s to.
Achnanthes rainutissima
Achnanthes oestrupii v.
Achnanthes sp.
Achnanthes suchlandtii
. dub ia
n i ncke i
n i ncke i ?
cur ta
1 anceo lata
Actinocyclus noriranii f. subsalsa
AmphipIeura pellucida
Amphora ova I i s
Amphora ovalis v. aff ins
Amphora ovalis v, pediculius
Amphora perpusilla
Amphora sp.
Amphora thumensus
Anomoeoneis vitrea
Asterionella forrrosa
CaI one is sp.
Cocconeis diminuta
d i scuILS
placentula v. euglypta
placertula v. lineata
thutr.ensis
ant i qua
ant i qua?
at orrus
comensi s
comensis - auxospore
correns i s v . 1
c o rii e n s i s v . Z
con ta
coirta - auxospore
corrta v. o I i gact is
crypt i ca
kuetz i ng iana
meneghi n iana
m i ch igan iana
michiganiana - auxospore
oce I I ata
Coccone i s
Cocconei s
Coccone i s
Coccone i
Cyclotel
Cyclotel
CycIote
Cyclote
Cyclote
CycIote
Cyclote
CycIote
Cyclote
Cyclote
Cyclote
CycIote
CycIote
CycIote
CycIotella
CycIoteI la
s
a
a
a
a
a
a
a
a
a
a
la
la
la
la
Gr un.
(Kutz.) Grun.
Gr un .
Hust.
A. Mayer
Re in. in Patr . £ Re i m.
Grun.
(Grun.) Hust.
(Kutz.) Brun.
Grun.
(Breb.) Greg.
Grun.
(Guerm. t Hang.) Reicn.
(Guerm. £ Mang.) Rein.
(M. Sin.) Grun.
H.L. Sm.
Kutz.
Hust .
Hust.
(Juh I ,-Oannf.) Hust.
(Kutz.) Kutz.
(Kutz.) Kutz.
(Kutz.) V.H. ex DeT.
(Kutz.) V.H. ex DeT.
(Grun.) Grun.
(Mayer) A. Cl.
(Grun.) Patr. £ Re im.
Hass.
Pant.
(Schum.) Cl.
(Ehr .) Cl .
(Ehr .) Cl.
A. Mayer
W. Sm.
W. Sir.
Pant.
Gr un.
(Ehr.) Kutz.
(Ehr.) Grun.
Re i m. et a I.
Thw.
Kutz.
Skv.
Pant.
-------
240
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV 7AXON AUTHORITY
6AC
Cyc I otel la
Cyc I otel la
CycIote I I a
Cyclotel la
CycIoteI la
CycIoteI la
CycIoteI la
CymatopIeu ra
Cymatop I eura
opercuI a ta
operculata unipunctata
pseudosteI I j gera
sp.
sp. SI
sp . - au xo spor e
ste I I i ge ra
e I I i pt i ca
so I ea
Cymbe I la cesat i i
Cymbella cistula v. gibbosa
Cymbe I la de I i catu la
Cymbella micrccephala
Cymbe I la tn i nuta
Cymbella minute v. silesiaca
Cymbella norvecjca
Cymbella prostrata v. auerswaldii
Cymbe I I a si nuata
Cymbe I la sp.
Cymbella trianculum
Denticula tenuis v. crassula
D latoma tenue
Diatoma tenue v. elongatum
Dip) one is e I I i pt i ca
D i p I one is ocu I a ta
Dip! one i s parnr.a
Dip! one is sp .
Entomoneis ornata
Eunot i a i nc i sa
Fragilaria brevistriata
brevistriata
brevistriata
capucina
capucina v. mesolepta
construens
construens
construens
construens
construens
crotonensis
leptostauron
pi nnata
pi nnata v.
pi nnata v.
sp.
vaucheriae
vaucheriae
affine
dichotomum
gracile
parvulum
sp .
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Fragilaria
Gomphonema
Gomphoneira
Gomphonema
Gomphonema
Gomphonema
v.
v.
i nfIata
subcapi tata
v.
v.
v.
v.
b i nodi s
m i nuta
subsaIi na
venter
intercedens
lancettu I a
v. cap i teI Iata
(Ag.) Kutz.
Hust .
Hust.
(Cl. £ Grun.) V.H.
(Breb. ) W.Sm.
(Breb. £ Godey) W. Sir.
(Rabh.) Grun. ex A.S.
Br un.
Kutz.
Grun.
Hi Ise
(Blei sch ) Re im.
Gr un.
(Rabh.) Re i m.
Greg.
(Ehr .) C I .
(Nag.) W. £ G.S. West.
Ag.
Lyngb.
(Kutz.) Cl.
(Breb.) Cl.
Cl.
( J.W. Ba i I .) ke im.
W. Sm.
Gr un .
(Pant.) Hust.
Gr un .
Desm.
(Rabh.) Grun.
(Ehr .) Grun.
(Ehr . ) Grun.
Temp . £ Per.
Hust.
(Ehr . ) G run.
Kitton
(Ehr.) Hust.
Ehr .
(Grun.) Hust.
(Schum.) Hust.
(Kutz.) Peters.
(Grun.) Patr.
Kutz.
Kutz.
Ehr. em. V.H.
Kutz.
-------
241
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
v« angustissima
subarcti ca
s i gnata
subsa I sa
• hur gar i ca
6AC Gyrosigma scictense
Me Ios i ra ambi qua
Me I os i ra a i starts
Me I os i ra granu lata
Melosira granulata
Me I os i ra i s I and i ca
Melosira i taI ica
Melosira italica suDsp.
Melosira sp.
Meridion circulare
Nav i cu la angI ica v.
Navicula angIica v.
Nav i cuI a capitate
Nav i cula cap i tata v
Navicula cincta
Navicula cryptocephaI a
Navicula cryptocepha I a v. veneta
Navicula exigua v. capitata
Nav i cula grac i I o ides
Nav i cuI a gregar i a
Nav icula irtegra
Navicula jaerneteIdtii
Nav icula I a custr i s
Navicula lanceolata
Navicula meniscu!us v. upsaliensis
Nav icula m in i ira
Navicula pseucoreinhardtii?
Nav i cula pupu la
Nav i cuI a rad i osa
Navicula radiosa v. tenella
Nav i cuI a re inharoti i
Navicula seminu I oides
Navicula seminulum
Nav icula sp.
Navicula tripurctata
Navicula tripunctata v. senjzonemoi
Nav icula tuscu I a
Navicula v i r i duI a
Neiduim sp. #1
des
N i tzsch i a
N i t z s c h i a
Nitzsch ia
Ni tzsch ia
N i tzsch ia
Ni tzschia
Ni tzschia
Ni tzschia
Ki tzsch i a
Nitzsch ia
N i tzsch ia
N i tzsch i a
Ni tzsch ia
ac i cular i oides
ac i cu lar i s
acu I a
acute
arnph i b i a
angustata
angustata v. acuta
bacata
cap i teI I a ta
conf i n i s
c o n f i n i s ?
d i ss ipata
f ont i cola
(Sul I i v. t. Worm I ey ) Cl
(Grun.) 0. Mull.
(Ehr.) Kutz.
(Ehr.) Ralfs
0. MulI.
0. Mul I .
(Ehr.) Kutz.
0. Mul I .
(Greg.) Ag.
Hust.
(Grun.) CI.
Ehr .
(Grun.) Ross
(Ehr.) Ralfs
Kutz.
(Kutz.) Rabh.
Patr .
A. Mayer
Donk .
(k. Sm.) RaIfs
Hust.
Greg.
(Ag.) Kutz.
(Grun.) Grun.
Gr un.
Patr .
Kutz.
Kutz.
(breb. ) Cl. £ Mo I I.
(Grun.) Grun.
Hust.
Grun .
(O.F.MulI.) Bory
(Breb. ex Grun.) V.H.
Ehr .
(Kutz.) Ehr.
Arch, non Hust.
(Kutz.) W. Sm.
Hantz. ex Cl . I Gr un.
Hantz.
Grun.
(W. Sm.) Grun.
Gr un .
Hust.
Hust.
Hust.
Hust.
(Kutz.) Gr un.
Grun .
-------
242
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
8AC -sNitzschia frustulum
~ Nitzschia frustulum v. minutula
" Nitzschia gancersheim i ensis
-Nitzschia gracilis
-N i tzsch ia i mp ressa
^Nitzschia kuetzingiana
-Nitzschia lauerburgiana
Nitzschia linear is
Nitzschia pa Iea
Nitzschia palea v. debilis
Nitzschia paleacea
N~i tzsch ia pura?
ffitzschia recta
N'itzschia romana
N-J tzsch ia sociabi I i s
Nitzschia sp.
N'itzschia spicUum
'•Nitzschia subacicularis
"Nitzschia sublinearis
'Nitzschia sublinearis?
tiitzschia subrostrata
-N i tzsch ia tenu is
"Nitzschia valdestrita
Opephora mar ty i
Rh i zosoI en i a er i ens is
Rhizosolenia Icngiseta
Rh i zosoI en ia sp.
Rhoiocosphenia curvata
Skeletonema pctairos
Stauroneis smfthii v. rcinuta
Stephanodiscus alpinus
Stephanodiscus
Stephanod i scu s
Stephanod i scus
S tephanod i scus
S tephanod i scus
Stephanodiscu s
Stephanod i scus
S tephanod i sc us
S tephanod i sc us
S tephanod i scus
Stephanod i scus
Stephanodiscus
Stephanod i scus
S tephanod i scus
a Ip inus?
binder anus
b i nder anus?
hantzsch i i
m i nu tus
n iagarae
sp.
sp. S03
sp. -auxospore
subt tlis
tenu is
tenuis v. #01
tenu is v. #02
tenu i s?
tran si I van i cus
Stephanod i scus
Sur i re I I a angusta
Synedra amphicephaI a v.
Synedra eye Iopum
Synedra delicatissima v
Synedra fame i I i ca
Synedra f i I if ormi s
austr i ca
angust iss ima
(Kutz. ) Grun .
Kr asske
Hantz.
Hust .
Hi Ise
Hust.
W. Sir.
(Kutz.) W. Sm.
(Kutz. 1 Grun .
Gr un .
Hust .
Hantz.
Grun .
Hust.
Hust .
Hust.
Hust.
Hust.
Hust .
W. Sir.
Aleem £ Hust.
Her i b.
H.L. Sm.
Zach .
(Kutz. ) Grun.
(Ueber) Hasle
Haw.
Hust.
Hust .
(Kutz.) Krieg.
(Kutz. ) Kr ieg.
Grun.
Gr un .
Ehr.
£ Evens,
(Van Goor )
Hust.
A. C I
Hust.
Pant.
Kutz.
(Grun. ) Hust.
Br ut schy
Gr un.
Kutz.
Grun.
-------
243
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
BAG
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
T a b e I 1 a r i a
Tabe I I ar i a
f i I i f oriri s
mini scula
paras i t i ca
rad i ans
sp.
u I na
u I na
u I na
v. e x i I i s
v. chaseana
v . dan i ca
ulna v . I on gi ss ima
f erestrata
ferestrata v. geniculata
Tabe I lar i a
Tabe I (aria
fIocculosa
fIocculosa
Ii near i s
CAT VacuoIar i a sp •
CHL Ankistrodesmus
Ankistrodesmus
Ank i strodesmus
Ank i strodesmus
Arthrodesmus bi
fa Ic at us
geIi factum
sp. #01
sp.?
f idus
Botryoc occus
Carte r i a sp.
Chlamydocapsa
ChIamydocapsa
ChIamydomonas
Ch tamydoironas
Chlamydoironas
C I osteri ops i s
C I ost er i urn
C I oster i urn
CoeI astr urn
CoeI astr urn
Coelastrum
Coenocyst i s
Braun i i
plank toni ca
sp.
sp.
sp. - ovo i d
- sphere
sp
sp.
ac i cular e
grac i le
carrbr i cum
m i cropor urn
sp.
sp.
Co smar i um sp .
Crucigenia irregularis
Crucigenia quacrata
Crucigenia rectangu laris
D i ctyosphaer
D i ctyosphaer
EIakatothr i x
Elakatothr i x
EIakatothr i x
G I oedact i n i urn
Go I enk i n t ps i s
Green cocco i d
Gr een cocco i d
Green cocco i d
Green coccoid
Green cocco i d
Green coccoid
um ehrenbergianum
urr pu I chel I um
geI at i no sa
v i r idi s
viridi s?
I irrne t i cum
sp.
#04
- aci cular
- bac iI I iform
- b i c e I I s
- fus iform
A. C I.
Gr un.
W. Sm.
Kutz.
(Nitz.) Ehr.
Thomas
(Kutz.) V.H.
(W. Sm.) Brun.
Kutz.
A. Cl .
(Roth) Kutz.
Koppen
(Corda) Ralfs
(Chod.) Bourr.
Br eb.
Kutz.
(w. £ G.S. West) Fott
T. West
Br eb .
Arch .
Nag. in A
Wi II e
Mor r en
A. Braun
Nag.
Wood.
Wi I le
(Snow)
(Snow )
Braun
Printz
Printz
G . M . Sm .
-------
244
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
CHL Green coccoid
Gr een coccoid
Gr een coccoid
Green coccoid
Gr een cocco i d
Gr een coccoid
Kirchneriella
Monoraph i d i urn
Monoraph i d i urn
Monoraph i d i urn
Monoraph id i urn
Monoraph id i urn
Monoraph id i urn
Nephrocyt i urn
Nephrocyt i urn
Gedogonium sp
- fusiform bicells
- oocyst i s-l ike bi ceI I
- ova I
- ren i f orm
- sphere
- sphere ( large)
conto r ta
contor turn
i r reguI are
ir i nut urn
saxat i I e
set i f orraae
torti le
Agarch ianum
I linnet i cum
Oocyst i s sp.
Oocystis sp. #1
Oocyst is borge i
Oocyst is crassa
Oocyst i s I acustr i s
Oocys t i s mar s en i i
Oocyst is parva
Oocyst is pusi I I a
Oocyst i s so I i tar ia
Oocyst i s submar i na
Ped iastrurn sp.?
Phacotus minuscula
Phacotus sp.
Planktonema lauterbornii
PIank tonema sp .
Pter omona s sp .
Pyramidomonas sp.
Scenedesmus act-ir, i na tus
Sceneoesirus
S c e n e d e s nr u s
Scenedesirus
Scenedesmus
Scenedesmus
Scenedesmus
Scenedesmus
Schro eder i a
Sphae reI Iocys t i s
Sphae re I Iocyst i s
eccr nis
quaar i cauda
quadricau da v.
s ec ur if or mi s
ser ratu s
sp.
sp inosus
set i ge r a
I a cu str i s
lateral is
I ongsp i na
Sphaerocystis schroeteri
St i chococcus sp.
Tetraedron caudatum
Tetraedron minimum
Tetraspora lacustris
Tetrastrum glabrum
Treubaria planktonica
Treubar i a set i gera
(Schirid.) Bohlir,
(Thur.) Kom.-Legn.
(G.M. Sm.) Kom.-Legn.
(Nag.) Kom.-Legn.
Kom,-Legn.
(Nyg.) Kom.-Legn.
(H. £ h.) Kom.-Legn.
Nag.
(G.M. Sm.) G.M. Sm.
Snow
Mi ttr . in Wi ttr. £ Nord,
Chod.
Lemm.
West £ West
Hansg.
Wi ttr . in Mi ttr . £ Nor d,
Lagerh .
Bour r.
SchmidIe
(Lagerh.) Choa.
(RaIfs) Chod.
( Tur p. ) Breb.
(Chod.) G.M. Stn.
Playf.
(Corda) Bohlm
Chod .
(Schroed.) Lemm.
Skuja
Fott £ Novak.
Chod.
(Cor da) Hansg.
(A. Braun) Hansg.
Lemm.
(G.M. Sm.) Korch.
(Arch.) G.M. Sm.
-------
245
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTDN (1983)
UIV TAXON AUTHORITY
CHR Bi tr i ch ia chodat i i
B i tr i ch j a ohri di ana
Chromul ina sp.
Chrysococcus sp.?
Chrysolykos angulatus
Chrysolykos planktonicus
Chrysolykos skujae
ChrysoIykos sp.
Chrysosphaere I I a longispina
D i nobr yon - cyst
Dinobryon acuirinatum
Dinobryon bavaricum
D i nobr yon bor ge i
Dinobryon cylinoricum
Oinobryon divergens
Oinobryon eurystcma?
Dinobryor sertularia
D i nobr yon soc i a Ie
Dinobryon sociale v.
Dinobryon sociale v.
D i nobr yon sp•
Dinobryon stokesii v.
Dinobryon tubaeformae
Dinobryon utriculus v
Halobryon sp . ?
Haptophyte sp.
airer i canum
sti ptatum
ep i p lank ton i cum
. tabeI Iar ia e
sp,
sp.
sp.
sp.
Kephyr i on
Kephyrion
Kephyr i on
Kephyr i on
Kephyr i on
Kephyr ion
Kephyr i on
Kephyr i on
Ma I Iomonas
Mai Iomonas
Ma I Iomonas
Qchromonas
Ochromonas
Ochromonas
Ochromonas
Paraphysomonas
Paraphysomonas
Pseudokephyr i on
Pseudokephyr i on
Pseudokephyr i on
Pseudokephyr i on
Pseudokephyr i on
Un ident i f ied
Un ident i f i ed
cupu I i for mae
do I i oI urn
rub i-caIu st r i
#1 -Pseudokephyrion entzi
#2
#3
sp i rale
majcrens is
sp .
sp. #3
sp.
sp. - ova I
sp. - ov oi d
sp. - sphere
sp.
sp.?
con i cuir
I at urn
ir i I lerense
sp. #1
undu lat i ss imum
cocco i a - ovo i 0
coccoi a - sphere
(Rev .) Chod.
(Fott) Mich.
(Wi I len) Niauw.
Mack .
(Nauw.) Bourr.
Laut. em. N i ch.
Rutt.
Imhof
Lemm.
Imhof
Imhof
(Stokes) Lemm.
Ehr .
Ehr .
(Br unnth.) Bac hm,
(S te in) Lemrr,.
Sku ja
Nyg.
Lemm.
Conr .
Conr .
Conr .
(Lack.) Conr.
Skuja
(Sen ill.) Schuir.
(Sen i I I . 1 Schutn.
Mich.
Scherff.
Un identif i ed
Un i dent i f i ed
coccoi ds
I or ica te -
sphere
-------
246
SPECIES LIST - LAKE MICHIGAN PHYTOPLANKTON (1983)
UIV TAXON AUTHORITY
CHR Unidentified I oricate-fI age I I ate sphere
COL
CRY
Bicoeca campanulata
Bicoeca lacustris?
B i coeca m i t ra v.?
Bicoeca sp.
Bicoeca sp. *C4
B i coeca tub if ormi s
Codonosiga sp.
Co I or less f lage Mate
Co I or I ess f I age I late
Colorless flagellates
Hast i geI I a sp.
Monos iga ovata
Salpingoeca arrphcrae
SaIp ingoeca grac iIi s
SaIp ingoeca sp.
Stylotheca aurea
- ovoid
- sphere
Chroomonas
Chroomonas
Chroomonas
Chroomonas
Cryptomonas
Cr yptomonas
Cryptomonas
Cr yptomonas
Cryptomonas
Cryptomonas
Cr yptomonas
Cr yptorconas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cr yptomonas
Cryptomonas
Cr yptomonas
Rhodomonas
Rhodomonas
acita
caudata
norstedt i i
pochmann i
- cyst
brev i s
brev is?
caudata
er csa
ercsa v. reflexa
I obata
mar sson i i
rrar sson i i v. ?
o vat a
parapyrenoidifera
phaseolus
pus iI la
pyreno i oi fer a
reflexa v. er osa
rostrat if ormi s
sp.
tenu i s
tetrapyreniodiosa
lacustr i s
lens
CYA
Rhodomonas mi nuta
Rhodomonas roinuta v.
Senn i a par vuI a
Senn ia parvuI a?
Anabaena flos-aquae
Anabaena sp.
Anacyst is mar i na
nannoplankt i ca
(Lack.) Bourr. em. Skuja
J. Clark
Skuja
Kent
Kent
Clark
(Bachm.) Bo Ioch.
Uterm.
Ge i t.
Hansg.
Huber-Pest.
Schi I I .
Schi I I .
Schi I I .
Ehr.
Marss.
Korsch.
Skuja
Skuja
Ehr .
Skuja
Skuja
Bachm.
Geit I .
Skuja
Pasch.
Skuja
Pasch. t kutt.
Pasch. £ Rutt.
Skuja
Skuja
Skuja
Skuja
(Lyngb.) Breb.
(Hansg.) Dr. t Dai ly
-------
SPECIES LIST - LAKE MICHIGAN PHYTQPLANKTON (1983)
DIV TAXON AUTHORITY
247
CYA Anacystis montana
Anacystis montana v. minor
Anacyst i s therrra I is
Aphanothece gelatinosa
Coccochloris elabans
Coccochloris peniocystis
Coe I osphaer i uir, naegelianum
DactyIococcopsis Smithii
DactyIococcopsis sp.
Gioeothece ruprestris
Gomphosphaeria lacustris
Lyngbya limneticuro
acardh i i
Iimnet i ca
I imnetica?
ir in ima
sp.
subbre v i s
tenu i s
tenu i s v . natans
tenuis v. tergistina
bIue-g reens
PYR
UNI
Osci
Osc i
Osc i
Osc i
Osci
Osc i
Osci
Osc i
Osc i
ato r i a
ato r i a
ato r i a
ato r i a
ato r ia
ato r i a
ator i a
a to r i a
ator i a
Unident if fed
EUG Euglena sp.
Amph i d in i urn sp.
Ceratium hirundinella
D i nof I age I late cyst
Gymnod i n i urn sp•
Gymnodiniurn sp. #1
Gymnodiniurr sp. #2
Gymnod i n i urn sp. #3
P er i d i n i urn c i nc turn
Peridinium inconspicuum
Per i din i urn sp .
Unident if i ed
Un ident if i ed
Unident i f i ed
Un ident i f i ed
Un i dent i f i ed
ccccoi d fI age Ilates
f lagel late #01
f lagel late #03
f I age I late - ovo i d
flagellate - spherical
Dr. £ Da iIy
Dr. £ Dai ly
(Menegh. ) Or. £ Dai I y
(Henn.) Lemm.
Or . £ Da iIy
(Kutz. ) Dr . £ Daily
Unger
Chod. £ Chod.
(Lyngb.) born.
Chod.
Lemm.
Gom.
Lemm.
Lemm.
GickIn.
S c h m i d .
C.A. Ag.
Gom.
(Kutz.) Rabh.
(O.F .hulI.) Schrank
(MulI.) Ehr.
Lemm.
-------
248
Table B,
Phytoplankton
Species List: Lake Huron
-------
249
SPECIES LIST - LAKE HURON PHYTOPLANKTON 11983)
OIV TAXON AUTHORITY
BAC
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Ac hnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Ac hnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Amphipleura
aff inis
bi asolett i ana
brevipes v. intermedia
cI eve i
c I eve i v . cost rata
consp i cua?
aetha
ex igua
exigua v. heterovalva
f I exe I la
ha uckj ana
anceolata
anceolata v. dubia
apponica v. ninckei
aterostrata
i near i s
i near is to. cur ta
marg i nuIata
mi crocepha la
m i nut i ss ima
sp.
pe I Iuc i aa
v. grac iI Iima
Amphora cotfeiformis
Amphora inariensis
Ampho ra ova I i s
Amphora oval is v. pediculius
Amphora perpusilla
Amphora sp•
Anomoeoneis vitrea
Asterionella forirosa
Asterionella forirosa
CaI one i s bac iI I urn
Cocconeis diminuta
Cocconeis disculis
Cocconeis placentula v. euglypta
Cocconeis placertula v. lineata
CycIostephanos duoius
CycIotelI a ant i qua?
catenata
comens i s
cofrensis - auxospore
coirens i s v . 1
correns i s v . 2
c o m t a
comta - auxospore
coirta v. #2
corrta v. o I igact is
crypt ica
kuetz ingiana
kuetz ing iana v.
kuetz i ng iana v.
kuetz i ng iana v.
Cyclotel la
Cyclotella
Cyc I otella
CycIoteI 1
Cyclotel I
Cyclotel I
CycIotel 1
CycIotelI
Cyclotel
Cyc I oteI
CycIoteI
CycIotel
CycIotel
Cyclotel
pIane tophora
plane tophora?
rad i osa
Gr un .
(Kutz.) Grun.
(Kutz.) Cl.
Grun.
Hust.
A. Mayer
Hohn £ HelIerm.
Grun .
Kr as ske
(Kutz.) Brun.
Grun.
(Breb.) Greg.
Grun.
(Guerm. £ Mang.) Rein.
Hust.
(M. Sm.) Grun.
H.L. Sm.
Grun.
(Kutz.) Grun.
Kutz.
(Kutz.) Kutz.
(Ag.) Kutz.
Kr am.
(Kutz.) Kutz.
(Kutz.) V.H. ex DeT.
(Grun.) Grun.
(Grun.) Patr. £ Reim.
Mass.
(Hantz.) Grun
(Grun.) CI.
Pant.
(Schum.) Cl.
(Ehr.) Cl.
(Ehr.) Cl.
(Fr i eke ) Round
M. Sm.
Br un .
Grun.
(Ehr.) Kutz.
(Ehr.) Grun.
Re i m. et al.
Thw.
F r i c k e
Fr i eke
Fr icke
-------
250
SPECIES LIST - LAKE HURON PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
BAG Cyclotella meneghintana
Cyclotella michiganiana
Cyclotella ocellata
Cyclotel la operculata
Cyclotella pseudoste I I igera
Cyclotella sp.
Cyc lotel la sp. #1
Cyclotel la sp. #2
Cyclotella sp. - auxospore
CycIoteI la ste I I igera
Cymatopleura solea v. apiculata
Cymbella angustata
CymbeI I a laev i s
Cymbella micrccepha la
CymbeI I a m i nuta
Cymbella minuta v. silesiaca
Cymbella navicu I iformjs
CymbeI la sp.
Cymbella trianculum
Dent i cu la sp.
Denticula tenuis v. crassula
D iatoma tenue
Diatoma tenue v. elongatum
Di pI one is eI I i pt i ca
D i pI one is ooIongeI I a
D i pI one i s ocu I sta
Entomoneis ornata
Eunot ia praerupta
Fragilaria brevistriata
Fragilaria brevistriata v. subcapitata
Fragilaria capucina
Fragilaria capucina v. mesolepta
Fragilaria construens
Fragilaria construens
Fragilaria construens
Fragilaria construens
Fragilaria construens
Fragilaria crotcnensis
Fragilaria intermedia v
Fragilaria leptostauron
Fragilaria leptostauron
Fragilaria pi nnata
Fragilaria pinnata v.
Fragilaria pi nnata v.
Fragilaria sp.
Fragilaria vaucheriae
Gomphonema angustatum
Gomphoneira dichotomum
Gomphoneir.a grac i le
Gomphonema olivaceum
Gomphonema parvulum
Gomphonema sp.
v.
v.
v.
v.
minuta
pumiI a
subsa I i na
venter
fat lax
. dub ia
intercedens
lancettuI a
Kutz.
Skv.
Pant.
(Ag.) Kutz.
Hust.
(Cl . t Grun.) V.H.
(W. Sm.) Ralfs
(W. Sm.) Cl.
Naeg. ex Kutz.
Gr un .
Hi Ise
(B le isch ) Re im.
Auer sw.
(Ehr .) CI.
(Nag.) W. £ G.S. West.
Ag.
Lyngb.
(Kutz.) Cl.
(Naeg.ex Kutz.) Ross
(Breb.) Cl.
( J.W. Ba i I.) Re im.
Ehr.
Grun.
Grun.
Desm.
(Rabh.) Grun.
(Ehr .) Grun.
Temp . £ Per •
Grun.
Hust.
(Ehr .) Grun.
Ki tton
(Grun.) Stoerm. £ Yang
(Ehr.) Hust.
(Grun.I Hust.
Ehr.
(Grun.) Hust.
(Schunu ) hust.
(Kutz.) Peters.
(Kutz.) Rabh.
Kutz.
Ehr. em. V.H.
(Lyngb.) Kutz.
Kutz .
-------
251
SPECIES LIST - LAKE HURON PHYTDPLANKTON (1983)
OIV TAXON AUTHORITY
BAC
Hantzschia amphioxys
Me 1 os i ra d i stans
Me 1 os i ra d i stans?
Melosira granulata
Melosira granulata v. angustissima
Me 1 os i ra i s 1 and i ca
Melosira italica subsp. subarctica
Melosira sp.
Navicula acceptata
Navicula atornus
Navicula capitata v. 1 unebur gens i s
Na v icu la c i ncta
Navicula confervacea
Navicula ctfnterta v. biceps
Navicula cr yptocepha 1 a v. veneta
Navicula gottlandica
Nav i cu la med i ccr i s
Nav i cu 1 a m i n i ma
Nav i cu la mura 1 i s
Nav i cu 1 a mura 1 i s?
Navicula mutica
Navicul a perpusi 1 la
Nav i cu la rad i osa
Navicula radiosa v. parva
Navicula raaiosa v. tenella
Navicula seminulum
Nav i cu 1 a s im i 1 i s?
Nav i cu la sp.
Nav i cu la sp . 816
Navicula sp. #18
Navicula submtralis
Navicula subt i 1 i ss i ma
Nav i cu la tant u la
Navicula viridula v. avenacea
Navicula viridula v. rostellata?
Nitzschia ac i cu 1 ar i o i cies
Nitzschia acicularis
Nitzschia acu la
Ni tzsch ia amph ib ia
Nitzschia angustata
Nitzschia angustata v. acuta
Nitzschia confinis
Nitzschia diss ipata
Nitzschia font! co la
Nitzschia frustulum
Nitzschia frustulum v. perpusilla
N i tzschia grac i 1 is
Nitzschia kuetzmgiana
Nitzschia lauerburg ia na
Nitzschia pa 1 ea
Nitzschia paleacea
N i tzsch ia pura
( Ehr . Grun .
(Ehr. Kutz.
(Ehr. Kutz.
(Ehr. Ralfs
0. Mu 1.
0. Mu 1.
0. Mu 1.
Hust.
(Kutz.) Grun.
(Grun. ) Patr .
(Ehr.) Ralfs
Kutz.
(Am.) V.H.
(Kutz. ) Rabh.
Grun .
Krasske
Gr un .
Gr un .
Gr un •
Kutz.
(Kutz.) Grun.
Kutz.
Wa 1 lace
(Breb. ) Cl . 1 Mo I 1 .
Grun.
Krasske
Hust.
Cl.
Hust.
(Breb.) V.H.
(Kutz.) Cl.
Arch, non Hust.
(Kutz.) W. Sm.
Hantz. ex C 1 . £. Gr un .
Grun.
(W. Sm.) Grun.
Grun.
Hust.
(Kutz. ) Grun.
Grun .
(Kutz. 1 Grun.
(Rabh. ) Gr un .
Hantz.
Hi Ise
Hust.
(Kutz.) W. Sm.
Gr un .
Hust.
-------
252
SPECIES LIST - LAKE HURON PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
BAG
N i tzsch i a
N i tzsch i a
N i tzsch i a
N i tzsch i a
N i tzsch la
Ni tzschia
Ni tzschia
Nitzschia
Opephora
pus iI la
recta
romana
rosteI lata
sp.
sub I i near i s
subrostrata
tenu i s
mar ty i
Pinnularia tn i cr cstaur on
Rhizosolenia eriensis
Rh i zosoI en ja sp.
Stephanodiscus alpinus
S tephanod i sc us
S tephanod i scus
Stephanod i scus
Stephanod i scu s
Ste phanod i sc us
S tephanod i scus
S tephanoc i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
S tephanod i sc us
S tephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Sur i re I I a ovata
Surirella ovata v. salina
Synedra amphicephaI a v. austrica
eye Iocum
de I i cat i ss i ma
deli cat i ss i ma
fame i Ii ca?
f iI if crmi s
f i I if crmis v.
m i ni scuI a
nana
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Tabe Maria
Tabe I lar i a
Tabe I I ar i a
alpinus - auxospore
aIp i nus?
b inderanus
b i nder anus?
hantzsch ii
minu tus
n iagarae
niagarae - auxospore
sp.
sp. #03
sp. #05
sp. -auxospore
tenu i s
tenu is v. #01
tenu is v. #02
tenu i s?
t ran s i I van i cus
v. angust iss iroa
ex i I is
paras i t
rad i ans
rumpens
rumpens
sp.
uIna v .
uIna v.
u I na v .
ca
v. f ragiIar i o i des
chaseana
dan ica
Iong i ss ima
f erestrata
ferestrata v. geniculata
fIoccuIo sa
(Kutz.) Grun. em. L.-B.
Hantz.
Grun.
Hust.
Must.
Hust.
W. Sir.
Her i b.
(Ehr .) C I.
H.L. Sin.
Hust.
Hust.
(Kutz.) Kr i eg.
(Kutz.) Krieg.
Grun.
Gr un.
Ehr .
Hust.
Hust.
Pant.
Kutz.
(M. Sm. ) Hust.
(Grun.) Hust.
Brut schy
W. Sm.
Gr un.
Kutz.
Grun .
A. C I .
Gr un.
Heister
W. Sm.
Kutz.
Kutz.
Grun.
Thomas
(Kutz.) V.H.
(H. Sm.1 Br un.
Kutz.
A. Cl.
(Roth) Kutz.
-------
253
SPECIES LIST - LAKE HURON PHYTOPLANKTON (1983)
OIV TAXON AUTHORITY
BAG Tabellaria flocculosa
Tabe Maria sp.
ThaI assjrosira sp.
I ineari s
Koppen
CAT
CHL
Vacua I ar i a
Vacuo I ar ia
sp .
sp.?
falcatus
falcatus v.
gelifactum
sp. #01
sp. #02
spiral is
stipitatus?
plank ton i ca
sp.
sp.?
sp.
sp. - ovo i a
sp. - sphere
Ank i s trodesmus
Ank i strodesmus
Ank i s trodesmus
Ank i strodesmus
Ank i strodesmus
Ank i strodesmus
Ank i strodesmus
Botryococcus Brauni i
Ch I amydocapsa bacillus
Ch lamydocapsa
Ch I amydocapsa
Ch lamydocapsa
Ch lamydomonas
Ch lamydomonas
Ch I amydomonas
Coelastrum microporum
Cosmar i urn sp .
Cosmar ium sp. »1
Crucigenia irregularis
Crucigenia quadrata
Crucigenia r e ctangu lar i s
D i c ty osphaer i urr. pulchellum
Ech i nosphaere I I a limnetica
Elakatothrix gelatinosa
E I aka to th r i x v i r i di s
Eudor i na el egars
France i a ova I i s
G I oeocyst is sp. #3
Go I enk i nia r aa i ata
Green coccoid #02
coccoid
coccoid
coccoid
cocco i d
cocco i d
coccoid
cocco i d
cocco i d
K i r chner i e I I a
Lager he i in i a c i I iata
Micractinium pus ill urn
Monoraph i d i urn contortum
Monoraph i d i urn convolution
Monoraph i d ium (rinutum
Monoraph id i urn saxat i I e
mirabiI is
Green
Green
Green
Green
Green
Green
Green
Green
#03
- ac i cu lar
- bac i I I if orrn
- bic el Is
- fus i form
- ova I
- sph er e
conto r ta
(Corda) Ralfs
(West £ West) G.S. West
(Chod.) Bour r.
(Turner) Lemm.
(Chod.) Kom.-Legn.
Kutz.
(Tei I.) Fott
(M. I G.S. West) Fott
Nag. in A. Braun
Wi I I e
Hor r en
A. Braun
Mood.
G • M • S m •
Mi I I e
(Snow) Pr intz
Ehr .
(France) Lemm.
(Chod.) UiI Ie
(Schnrid.) Bohiti,
(Lagerh.) Choa.
Freseni us
(Thur.) Kom.-Legn.
(Corda) Kom.-Legn.
(Nag.) Kom.-Legn.
Kom.-Legn.
-------
254
SPECIES LIST - LAKE HURON PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
CHL
CHR
Monoraphidium setiformae
Mougeotia sp.
Oocyst is sp.
Oocystis sp. »1
Oocystis Borgei
Oocystis crassa
Oocystis lacustris
Oocyst is mar s en i i
Oocystis parva
Oocystis pus i I la
Oocyst is so Ii tar ia
Pyramidomonas sp.
Scenedesmus abcndans
Scenedesmus
Scenedesirus
Scenedesmus
Scenedesmus
Scenedesmus
Scenedesmus
Scenedesrrus
Scenedesmus
dent i culatus
eccrn i s
secu r if or mi s
secur if oriri s ?
serratu s
sp.
subsp i cat us
ve I itar i s
SphaereI Iocystis lateralis
Sphaerocystis schroeteri
St i chococcus sp.
Synechococcus sp.
TetrachI ore I I a alternans
Tetraedron minimum
Treubaria planktonica
Treubaria planktonica?
Treubaria setigera
B i tr i ch i a chodati i
Chrysolykos planktonicus
Chrysolykos sktjae
Chrysolykos sp.
ChrysosphaereI I a longispina
Dinobryon - statospore
Dinobryon acuiri i na turn
Dinobryon bavaricum
D i nobryon bor ge i
Dinobryon cylindricum
Dinobryon cylindricum
Dinobryon divergens
Dinobryon divergens -
Dinobryon eurystoma
Dinobryon sertularia
Dinobryor sertularia
D inobryon soc iaIe
D i nobryon soc i a Ie v .
D inobryon stokes i i v
Dinobryor utriculus
Haptophyte sp.
v . aIp i num
statospor es
v. pro tuberans
arrer i canum
• ep i pIanktoni cum
v . tabeI Iar iae
(Nyg.) Kom.-Legn.
Snow
Mi ttr . in W i ttr . i Nord,
Chod.
Lemm.
West £ West
Hansg.
Wittr. in Wi ttr. £ Nord.
(Kirch.) Chod.
Lagerh.
(Ralfs) Chod.
Playf.
Playf.
(Cor da) Boh I m
Chod.
Kom.
Fott t Novak.
Choa.
(G.M. Smith) Kors.
(A. Braun) Hansg.
(G.M. Sen.) Korch.
(G.M. Sro.) Korch.
(Arch.) G.M. Sm.
(Rev.) Chod.
Mack.
(Nauw. ) Bour r.
Laut. em. Nich.
Rutt.
Imhof
Lemm.
Imhof
(Imhof) Bachm.
Imhof
(Stokes) Lemm.
Ehr.
(Lemm. ) Kr i eg.
Ehr .
(Brunnth.) Bachm.
Sku ja
Lemm.
-------
255
SPECIES LIST - LAKE HURON PHYTCjPLANKTON (1983)
DIV TAXON AUTHORITY
CHR
COL
CRY
Kephyr i on
Kephyr i on
Kephyr i on
Kephyr i on
Kephyr i on
Ma I Iomonas
Ma I Iomonas sp•
Mai Iomonas sp.
Ochromonas sp.
Ochromonas sp.
Ochromonas sp.
Paraphysomona s
Paraphysoroonas
Pseudokephry i on
Pseudokephyr i on
Pseudokephyr i on
Pseudokephyr i on
Pseudokephyr i on
Uni dent i f i ed
Un i dent if i ed
cupu I i for mae
sp. #1 -Pseudokephyrion
sp. #2
sp. #3
sp i ra I e
sp.
#1
#3
entzi i
- ovoi d
- sphere
sp.
sp.?
entzi i
con icutr
I at urn
IT i I lerense
sp. #1
ccccoias
I or i ca te - ovo i d
Unidentified loricate - sphere
Bicoeca campanulata
6 i coeca crystal Iina
Bicoeca mitra v. suecica
B i coeca socia I i s
B i coeca sp.
Bicoeca sp. 804
Bicoeca tub if or mis
Colorless flagellates
Monos i ga ovata
Monos i gna ova I i s
Salpingoeca amphorae
Salpingoeca gracilis
Stylotheca aurea
Chroomonas
Chroomonas
Chroomonas
Cryptomonas
Cr yptomonas
Cr yptomonas
Cryptomonas
Cryptomonas
Cr yp toironas
Cryptomonas
Cryptomonas
Cr yptomonas
Cr yptomonas
Cryptomonas
Cryptomonas
Cryptomonas
a c f t a
cabdata
norstedti i
- cyst
brev i s
caudata
er csa
ercsa v. reflexa
trar sson i i
obovata ?
ovata
parapyrenoidifera
phaseoI us
phaseolus ?
pus i I la
pyreno i ci fer a
Conr ,
(Lack.) Conr.
Conr .
(SchilI.)
(Sch ill.)
Ni ch.
Schum.
Schum.
(Lack.) Bourr. em. Skuja
Sku ja
Skuja
Lauter b.
Skuja
Kent
Kent
Kent
Clark
(Bachm.) Boloch.
Uterm.
Ge it.
Hansg.
Schi II .
SchiI I.
Ehr .
Marss.
Skuja
Skuja
Ehr.
Skuja
Skuja
Skuja
Bachm.
Geit I.
-------
256
SPECIES LIST - LAKE HURON PHYTOPLANKTON (1983)
OIV TAXON AUTHORITY
CRY
CYA
BUG
Cr yptomonas
Cryptomonas
Cr yptomona s
Cryptomonas
Cr yptomonas
Rhodomonas
Rhodomonas
refIexa
rest rat if orm i s
sp.
tenu i s
tetrapyrenoidiosa?
Iacustr i s
I ens
Rhodomonas minuta
Rhodomonas minuta v.
Unidentified coccoid
nannop lankti ca
Anabaena circinalis
Anabaena sp.
Anacyst is mar i na
Anacystis montana v. minor
Anacyst is therira I is
Coccochloris elabans
Coccochloris peniocystis
CoeIosphaeri im Naegel ianum
Gomphosphaeria lacustris
Osc iI Iator ia
Osc iI Iato r i a
Osc iI Iator ia
Osc iI I ator i a
Iimnet i ca
rr i n ima
subbrev i s
tenu i s
Euglena sp.
Phacus sp.
TracheIomonas hispiaa
TracheIomonas sp.
PYR Amphidinium sp.
Ceratium hirundinella
Gymnod i n i urn sp.
Gymnod i n i urn
Gymnod i n i urn
Gymnod i n i urn
Gyirnod in i urn
Peridinium inconspi
Per i d i n i urn sp.
Peridinium sp. #02
sp.
sp.
sp.
sp.
#1
#2
#3
#5
UNI Un identi f i ed
Un i dent i fi ed
Un identi f ied
flagel late #01
f I age Mate - ovo i d
flagellate - spherical
Sku ja
Sku ja
Pasch.
Skuja
Pasch.
Pasch.
Skuja
Skuja
£ Rutt.
£ Rutt.
Rabenhorst
(Hansg .) Or . £ Da i ly
Or. £ Da i I y
(Menegh . ) Dr . £ Da iIy
Dr. £ Da i ly
(Kutz.) Dr. £ Da ily
Unger
Chod.
Lemm.
GickIn.
Schm id.
C.A. Ag.
(Perty ) Ste in em. DefI
(O.F.MuI I.) Schrank
Lemm,
-------
257'
Table C
Phytoplankton
Species List: Lake Erie
-------
258 .
SPECIES LIST - LAKE ERIE PHYTOPLANKTON (1983)
UIV TAXON AUTHORITY
SAC
Achnanthes
Achnanthes
Ac hnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Achnanthes
Act i nocycI us
Act i nocycI us
b i asoIet t iana
b i oret i
cI eve i
c I eve i v. rostrata
consp i cua
ex igua
haucki ana
lanceolata v. dubia
I emirerirann t
I inear is
I inear is f o.
m i cr ocep ha la
mi nut i ss ima
sp.
sp.?
sub laev i s
rorman i i f ,
sp.
cur ta
subsa I sa
roinuta
euglypta
lineata
Amphora oval is v. affins
Amphora ovalis v. pediculius
Amphora perpus ilia
Amphora sp.
Amphora tenuistriata
Anomoeoneis vitrea
Asterionella forir
-------
259
SPECIES LIST - LAKE ERIE PNYTOPLANKTON <1983)
DIV TAXON AUTHORITY
bAC CycIotel I a
Cyclotel la
CycIotel la
CycIotel la
Cyc lotel la
CyclotelI a
Cymatopleura solea
CyroatopIeura solea
CymbeI la at f i ni s
CymbeI I a
CymbeI la
CymbeI la
CymbeI la
Cymbe I I a
operculata
pseuaosteI I i gera
sp.
sp. SI
stelIige ra
wo Itereck i
v. apiculata
m i crccepha la
minuta
mi nuts v. si lesiaca
prostrata v. auerswaldii
pusi I la
CymbeI la sp .
Denticula tenuis v. crassula
0 iatoma anceps
Oiatoma tenue v. el on gat urn
Diatoma vulgare
0ip I one is ocu I ata
Entomoneis ornata
Fragilaria brevistriata
Fragilaria brevistriata v. inflata
Fragilaria capucina
Fragilaria construens
Fragilaria construens v. minuta
Fragilaria construens v. pumila
Fragilaria construens v. venter
Fragilaria crotonensi s
Fragilaria inter/red ia v. fallax
Fragilaria leptostauron
Fragilaria leptostauron v. dubia
Fragilaria nitzschicides
Frag i far i a pi nnata
Fragilaria pinnata v. lancettula
Fragilaria pinnata v. pinnata
Fragilaria sp.
Fragilaria vaucheriae
Gomphoneira clevei
Gomphonema dichotomum
Gorophonema parvulum
Gomphonema sp.
Gomphonema tergestinum
Gyrosigma attenuatuiri
Gyrosigma scictense
Melosira agassizii v. malayensis
he I os i ra di stans
Melosira distans v. limnetica
Melosira granulata
Melosira granulata v. angustissima
Melosira granulata?
Melosira i sI and i ca
(Ag.) Kutz.
Must.
(CI. £. Grun.) V.H.
Hust.
IBreb. i. Godey) W. Sm.
(W. Sm.) kalfs
Kutz.
Grun.
Hi Ise
(Sleisch) Reim.
(Rabh,) Reim.
Grun.
(Nag.) k. t G.S. West.
(Ehr.) Kirchn.
Lyngb.
Bory
(Breb.) CI.
(J.W. Bai I .) Re i m.
Grun.
(Pant.) Hust.
Oesm.
(Ehr.) Grun.
Temp. £ Per.
Grun .
(Ehr.) Grun.
Ki tton
(Grun.) Stoerm. £ Yang
(Ehr.) Hust.
(Grun.) Hust.
Grun •
Ehr.
(Schum.) Hust.
(Kutz.) Peters.
Fr icKe
Kutz.
Kutz .
(Grun. ) Fr i eke
(Kutz.) Rabh.
(SulIiv. L Wormley) CI .
Ostenf.
(Ehr.) Kutz.
0. MulI.
(Ehr.) kalfs
0. Mul I.
(Ehr.) Ralfs
0. MulI.
-------
260
SPECIES LIST - LAKE ERIE PHYTOPLANKTON 11983)
DIV TAXON AUTHORITY
hurgari ca
Iuneburgens i s
veneta
BAG Melosira italica subsp. subarctica
Melosira sp.
Navicula acceptata
Nav i cuI a angI i ca
Nav i cuI a capitate
Navicula capitata v,
Nav i cula cap i tata v <
Navicula c i nc ta
Navicula cocconeiformis
Navicula cryptocephaI a
Navicula cryptocephala v,
Navicula ex i gua
Navicula exigua v. capitata
Navicula lanceolata
Nav i cuI a meni scuI us
Navicula menisculus v. upsaliensis
Nav i cuI a minima
Navicula pseudoscutiformis
Nav i cuI a pupu la
Navicula radiosa v. tenella
Navicula salinarurr v. intermedia
Navicula seminulcides
Navicula seminulum
Nav i cuI a sp.
Nav icula stroen i i
Navicula terminate
Navicula tripunctata
Navicula viridula v. rostellata
Navicula vitabunda
Nav i cula zanon i
Ne id i um af f i ne
Ni tzsch13
Ni tzsch ta
N i tzsch ia
N i tzsch i a
Ni tzsch ia
Ni tzsch ia
N i tzsch ia
N 11 z s c h i a
N i tzsch ia
N i tzsch i a
Ni tzsch ia
N i tzsch ia
Ni tzschia
N i tzsch ia
N i tzsch ia
Ni tzschia
N i tzsch ia
N i tzsch ia
N i tzsch ia
Nitzschia
N i tzsch i a
ac i cuIar i o ides
ac i cular i s
acict'lari s?
acu I a
araphi D ia
angustata
angustata v. acuta
ap i cuIata
ar chba I di i
closter ium
conf in i s
d i ssipata
d i ss i pata v. media
f ont i co la
fr ustuI urn
gancershe im i ens i s
grac i I i s
hantzschiana
i nconsp i c ua
i ntermed i a
Kuetz i ng i ana
0. MulI.
Hust.
Rat f s
Ehr .
(Grun.) Ross
(Grun.) Pat r.
(Ehr.) Ralfs
Greg .
Kutz .
(Kutz.) Rabh.
Greg . ex Grun•
Patr .
(Ag.) Kutz.
Schum.
(Grun.) Grun.
Grun .
Hust.
Kutz.
(Breb.) Cl. £ Mo I I.
(Grun.) CI.
Hust.
Gr un.
Hust.
Hust.
(O.F.MulI.) Bory
(Kutz.) CI.
Hust .
Hust.
Pf i tz.
Arch, non Hust.
(Kutz.) W. Sni.
(Kutz.) W. Snu
Hantz. ex Cl. 6 Grun,
Grun .
(W. Sm.) Grun.
Gr un .
(Greb.) Grun.
L.-B.
(Ehr.) W. Sm.
Hust.
(Kutz.) Grun.
(Hantz.) Grun.
Grun.
(Kutz.) Grun.
KrassKe
Hantz.
Rabh.
Grun .
Hantz.
Hi Ise
-------
261
SPECIES LIST - LAKE ERIE PHYTOPLANKTON (1983)
DIV TAXON AUTHORITY
BAG
Ni tzsch ia
Ni tzschia
Ni tzsch ia
N i tzsch i a
Ni tzsch ia
N i tzsch ia
Ni tzschia
Nitzschia
Ni tzschia
Ni tzsch ia
Nitzsch ia
N i tzsch ia
N i tzsch ia
Nitzsch ia
N i tzsch ia
N i tzsch ia
N i tzsch ia
N i tzsch i a
Nitzschia
Ni tzsch ia
Ni tzschia
N i tzsch ia
Ni tzschia
Nitzsch ia
Rh izosoI en ia
Rh i zoso ten ia
debi I is
tenu i rostr i
kuetz irtgi oi des?
lauerburgiana
I inear i s
pa I ea
pa Iea v.
pa Iea v.
pa I eacea
puni la
pur a
pus i I la
r ecta
romana
r osteIlata
soc iab iIi s
sp.
sp i c LIc i des
subac icularis
sub I inear is
tenu is
tr op i ca
trybIi one I I a
trybli one I I a
trybIi one I I a
trybli one I I a
er iens is
Icngiseta
v.
v.
v.
debiI is
v i ctor iae
v i ctor i ae?
Rhi zosoI en ia sp.
Skeletonema pctairos
Stauroneis kriegeri
Stephanodiscus alpinus
Stephanodi scus
Stephanod i scus
Stephanoci scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanodi scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
Stephanodi scus
Stephanod i scus
Stephanod i scus
Stephanod i scus
S tephanod i scus
alpinus - auxospore
a Ip i nus?
binder anus
hantzsch i i
m inu tu s
minutus - auxospore
n iagar ae
- auxospore
v. magnif ica
sp.
sp.
sp.
sp.
Sur i r eI I a
Surirella
Surirella
Sur i r el I a
n iagar ae
n iagar ae
sp.
#03
#04
#07
"auxospore
tenu i s
tenu i s v. #01
tenu is v• #02
tenu i s?
b i rostrata
o vata
ovata v. pinnata
ovata v. sa I ina
Hust.
W. Sir.
(KutZ.) W. Sm.
(Kutz.) Grun.
Gr un.
Grun.
Hust.
Hust.
(Kutz.) Grun. em. L.-6.
Hantz.
Grun.
Hust.
Hust.
Hust.
Hust.
Hust.
W. Sir.
Hust.
(Arnott) A. Mayer
Grun.
Grun .
H.L. Sm.
Zach.
(Weber) Hasle £ Evens.
Patr.
Hust.
Hust.
(Kutz.) Krieg.
Grun.
Gr un.
Ehr.
Fr icke
Hust.
Hust.
Hust.
Kutz.
(W. Sm.) Hus.t.
(W. Sm.) Hust.
-------
262
SPECIES LIST - LAKE ERIE PHYTOPLANKTON (1983)
LlIV TAXON AUTHORITY
austr i ca
angust iss ima
BAG Sur i re I I a sp.
Sur i r e I I a turgida
Synedra acus?
amph i cephala v.
deli cat issi ma
deIi cat i ss i ma v.
f i I i f o r ITI i s
filiforiris v. exilis
rr i ni scu I a
paras 11 i ca
u I na v. Iong i ss i roa
f enestr ata
ferestrata v. genicutata
fIoccuIo sa
flocculosa v. linearis
sp.
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Synedra
Tabe
Tabe
Tabe
Tabe
Tabe
I ar i a
lar i a
I ar i a
I ar i a
I ar ia
ThaI assiosira fluviatilts
CAT Vacuolar i a sp .
CHL Actinastrum gracilimum
Anh i strodesmus sp. feO*!
AnKyra juday i
Car ter ia sp.
Car ter ia sp. -cvo i d
Carteria sp. -sphere
ChIamydocapsa planktonica
ChIamydocapsa
ChIamydomonas
Chlamydomonas
Ch tamydomonas
ChI orogon ium
sp.
sp.
sp. - ovoid
sp . - spher e
tr in imu m
ChIorogoniurn sp.
Closterium aciculare
Closter ium
Clo ster ium
Coelastrurn
CoeIastrum
CoeIastrum
Co smar i urn
par vu I urn
sp.
canbri cure.
m i cr opor urn
sp.
sp.
Crucigenia irregularis
Crucigenia quadrata
Crucigenia rectangu laris
Crucigenia tetrapedia
D i ct yosphae r i urr ehr enber g ianum
D i ct yosphaer i uir, pulchellum
Elakatothrix gelatinosa
Elakatothrix viridis
Eudor i na eIegars
France ia ova Ii s
Golenkinia radiata
Green F i lament
W. Sm.
Kutz.
(Grun.) Hust.
W. Sm.
Gr un.
Grun.
A. Cl.
Grun.
W. Sm.
(W. Sm.) Br un.
Kutz.
A. Cl .
(Roth) Kutz.
Koppen
Hust.
G.M. Smith
(G.M. Sm.) Fott
(W. £ G.S. West) Fott
Playf.
T. West
Nag.
Arch.
Nag. in A. Braun
Mi I I e
Mor ren
A. Braun
(Kirch.) W. £ G.S. West
Nag.
Wood.
Wi I le
(Snow ) Pr i ntz
Ehr .
(France) Lemm.
(Chod.) WiIle
-------
263
SPECIES LIST - LAKE ERIE PHYTOPLANKTDN (1983)
DIV TAXON AUTHORITY
#04
- aci cu I ar
- bac i I I iform
- bicel Is
- fusiform bicetls
- ova I
- ovo i d
- sph er e
CHL Gr een cocco i d
Green coccoid
Gr een coccoid
Gr een coccoid
Gr een coccoid
Gr een cocco i d
Green cocco i d
Green coccoid
Green flagellate - sphere
KirchnerieI I a contorta
K i rchner i eI la obesa
Lagerheimia balatonica
c iIiata
geneven si s
Iong i se ta v. major
quadr i seta
sp.
subsaIsa
Lager he im i a
Lager he i m ia
Lager he i m i a
Lagerhe i ir i a
Lagerhe i ir ia
Liger heimia
Lobomonas sp . ?
Micractiniuro p u s i I I urn
Monoraphidiurn contortum
Monorapfl i d i urn griffitrsii
Monoraphidiurn irregulare
Monoraphidium nirutum
Mougeotia sp.
Nephrocytium Agardhianum
Nephrocytiurn limneticum
Nephrocytium liirneticura?
Oedogonium sp.
Oocyst i s
Oocyst is
Oocyst is
Oocyst is
Oocyst i s
Oocyst i s
Oocyst i s
Oocyst is
Oocyst i s
Oocyst I s
Oocyst i s
Oocyst i s
Pandor ina
*1
sp,
sp,
sp.?
borge i
crassa
el Ii pt i ca
lacustri s
ma r sen ii
par va
pus i I I a
so Ii tar ia
submar i na
mor unr ?
v. minor
Paradoxia multiseta
Pediastrum boryanum
Ped i astrum
Ped i astrutn
Pediastrum
Ped i as trurn
Pediastrum
S c e n e d e s m u s
dup lex v .
dup lex v .
simplex
simplex v.
sp.
abtndan s
c lathratum
ret i cuIatum
duodenari um
Scenedesmus
Scenedesmus
actir, inatus
ar cuatus
(Schm id.) Bohlm
(W. fcest) Schmidle
(Scherf f. in KoI) Hind.
(Lagerh.) Choo.
(Chod.) Chod.
G.M, Sm •
(Lerom.) G.M. Sm.
Lemm.
Fr esen i us
(Thur.) Kom.-Legn.
(Berkel.) Kom.-Legn.
(G.M. Sm.) Kom.-Legn.
(Nag.) Kom.-Legn.
Nag.
(G.M. Sm.) G.M. Sm.
(G.M. Sm.) G.M. Sm.
Snow
Wittr . in Mi ttr. £ Nord.
M. West
Chod.
Lemm.
West £ West
Hansg.
Wi ttr. in Wi ttr. £ Nord.
Lagerh.
(Muell.) Bory
Swir.
(Turp.) Menegh.
(A. Braun) Lagerh.
Lagerh.
(Meyen) Lemm.
(Bail.) Rabh.
(Kirch.) Chod.
(Lagerh.) Chod.
Lemm.
-------
264 ,
SPECIES LIST - LAKE ERIE PHYTOPLANKTON (1983)
UIV TAXON AUTHORITY
CHL Scenedesmus arrrattis
Scenedesmus bicaudatus
Scenedesnr.us carinatus
Scenedesmus denticulatus
Scenedesmus eccrnis
Scenedesmus intermeaius
Scenedesmus interrreaius v. bicaudatus
Sceneaesrrus quadricauda
Scenedestrus s ecu r if or mi s
Scenedesmus sp.
Scenedesmus spinosus
Scenedesmus spinosus?
Schroederia setigera
SphaereI Iocystis lateralis
SphaereI I ops i s sp.
Sphaerocystis schroeteri
Staurastrum paradoxum
Staurastrurn sp•
St i chococcus sp.
Tetraedron caudatum
Tetraedr on m i n imum
Tetraedron mut i cum
Tetraedron regulare v. incus
Tetraspora lacustris
Tetrastrum heteracanthum
Tetrastrum staurogeniaeforme
Treubaria planktonica
CHR
Treubar ia
Treubaria
set
sp.
gera
B i tr i chia chodati i
Chrysolykos planktonicus
Chrysolykos skcjae
ChrysosphaereI I a longispina
Dinobryon acuirinatum
Dinobryon bavaricum
Dinobryon cylinaricum
Dinobryon divergens
Dinobryon sertularia
Dinobryon sociale v. arrericanum
0 i nobryon sp.
Dinobryon stokesii v. epipIanktonicum
Dinobryor utriculus v. tabellariae
Haptophyte sp.
Kephyrion cupuliformae
Kephyrion sp. #1 -Pseudokephyrion entzi
Kephyr i on sp. #2
Kephyrion sp. #3
Ma I I omonas sp.
Ochromonas sp.
Qchromonas sp. - ovoid
Paraphysomonas sp.?
(Chod.) G.M. Sm.
(Hansg.) Chod.
(Lernm. ) Chod.
Lagerh.
(RaIfs ) Choa.
Chod.
Hor tob.
(Turp. ) Breb.
PIayf.
Chod.
Chod.
(Schroed.) Lemm.
Fott t. Novak.
Chod.
Meyen
(Corda) Hansg.
(A. Br aun) Hansg.
( A . Br aun ) Hansg.
Te i1ung
Lemm.
(Nor dst.) Chod.
( Schroed.) Lemm.
(G.M. Srr.) Korch.
(Arch.) G.M. Sm.
(Rev.) Chod.
Mack .
( NiauM . ) Bour r .
Laut. em. Mich.
Rutt.
Imhof
Imhof
Imhof
Ehr.
(Brunnth.) Bachm.
Skuja
Lemm.
Conr .
-------
265 .
SPECIES LIST - LAKE ERIE PHYTOPLANKTDN (1983)
DIV TAXON AUTHORITY
CHR Pseudokephyr ion millerense
Pseudokephyrion sp. #1
Pseudotetraedron neglectum
Unidentified coccoids
Unidentified flagellate
Unidentified loricate - ovoid
Unidentified loricate - sphere
COL B coeca campanulata
B coeca crystaI Iina
B coeca sp.
B coeca sp. *01
B coeca sp. #G4
B coeca sp. #05
B coeca tubifcrir.is
Codonosiga sp.
Colorless flagellates
Colorless flagellates - colonial
Monosi ga ovata
Salpingoeca amphorae
Salplngoeca gracilis
Stelexmonas dichotoma
Stylotheca aurea
CRY Chroomonas acuta
Chroomonas norstedtii
Cryptomonas - cyst
Cryptomonas catoata
Cryptomonas curvata
Cryptomonas curvata?
Cryptomonas ercsa
Cryptomonas ercsa v. reflexa
Cryptomonas rrarssonii
Cryptomonas marssonii v.?
Cryptomonas ovata
Cryptomonas phaseolus
Cryptomonas pyrenoioifera
Cryptomonas reflexa
Cryptomonas rostrat iformis
Cryptomonas rostrat iformis?
Cryptomonas sp.
Rhodomonas lens
Rhodomonas minuta
Rhodomonas minuta v. nannoplanktica
CYA Agmenellum quadrupl icatum
Anabaena sp.
Anabaena spircides
Anacyst i s mar ina
Anacystis montana v. minor
Anacystis therrralis
Anacystis theriralis f. major
Nich.
Pasch.
(Lack.) Bourr. em. Skuja
Skuja
Skuja
Kent
Kent
Clark
Lack .
(6achm.> Bo I och.
Uterm.
Hansg.
Schi I I .
Ehr .
Ehr .
Ehr .
Marss.
Skuja
Skuja
Ehr .
Skuja
Geit I .
Skuja
Skuja
Skuja
Pasch. fc Rutt.
Skuja
Skuja
(rtenegh. ) Breb.
Kleb.
(Hansg.) Dr. i. Dai ly
Dr. £ Da i ly
(Menegh. ) Or. i Da i I y
(Lagerh. I Dr. £ Da iIy
-------
266
SPECIES LIST - LAKE ERIE PHYTOPLANKTON 11983)
DIV TAXON AUTHORITY
CYA
EUG
PYR
Aphanizomenon flos-aquae
Coccochlorts elabans
Coccochloris peniocystis
CoeIosphaeriurn dubiurn
CoeIosphaeriurn naegelianum
Gomphosphaeria lacustris
Merismopedia tenuissima
Osc iI lator ia
Osc iI I atoria
OsciI Iator ia
Osc iI I ator i a
I irnnet ica
subbrev i s
tenu is
tenu i s ?
Euglena sp.
TracheIomonas sp.
Amphidinium sp.
Ceratium hirundinella
Ceratium hirundinella - cyst
Gymnod in i urn sp.
Gymnodinium sp. H2
Gymnodiniurn sp. S3
Peridinium acicu I iferurn
Peridinium acicu I iferurn?
Peridinium inconspicuum
Per i d i n i urn sp.
UNI Unidentified
Unidentif ied
Unidentif i ed
flagel late #01
fI age I late - ovoid
flagellate - spherical
(L.) Ralfs
Dr. £ Da i ly
(Kutz. ) Dr. £ Da i ly
Grun. in Rabh.
Unge r
Chod.
Lemm.
Lemm.
Schm id.
C.A. Ag.
C.A. Ag.
(O.F .Mul I .) Schrank
(O.F.MulI.) Schrank
Lemm.
Lemm.
Lemm .
-------
267
Table D
Zooplankton Species List: Lake Michigan
-------
268
DIVISION
GREAT LAKES ZODPLANKTON SPECIES LIST
LAKE MICHIGAN
(1983)
TAXON
Ca lano i da
C I adocera
Copepoda
CycIopo i da
Harpact i co i da
Mys i aacea
Rot i fera
Ca lano i d -
Di aptomus
D i ap tomus
Di aptomus
0i aptomus
D j aptomus
Ep i schura
Eu ry temora
copepodi te
ash land i
mi nutus
oregonensi s
sici I is
si c iIo i des
lacustr i s
aff ini s
Limnocalanus macrurus
Senecella calanoides
A Iona af f i ni s
Bosmina longirostris
Camptocercus rectirostris
Ceriodaphnia lacustris
Chydori dae
Chydorus sphaericus
Daphnia catawba
Caphnia dubia
Daphnia galaeta mendota
Daphnia immatures
Daphnia longiremis
Daphnia middendorffiana
Daphnia puIi car i a
Daphnia retrorurva
Daphnia schod leti
Daphnia sp.
Diaphanosoma I euchtenbergianum
Eubosmina coregoni
Eurycercus lamellatus
Holopedium gtbberum
Ilyocryptus spinifer
Leptodora k i ndt i i
Polyphemus pediculus
Copepoda NaupIi i
Cyclopoid - copepodite
Cyclops bicuspidatus thomasi
Eucyclops prionophorus
Mesocyclops edax
Tropocyclops prasinus mexicanus
Harpact i co i da
My si s r el i eta
Ascomorpha sp.
Asplanchna priodonta
Brachionus quadridentatus
-------
269
GREAT LAKES ZOOPLANKTON SPECIES LIST
LAKE MICHIGAN
(19B3)
DIVISION TAXON
Rotifera Cephaloflella sp.
Co I Iotheca sp.
Conoch i Ic i des sp•
Conochi IDS unicornis
Encentrum sp.
Euchlanis sp.
F i Ii na Iong i seta
Gastropus sty Ii fer
Kellicottia longispina
Keratella cochlearis
Keratella crassa
Kerate1 la ear Ii nae
Ke rate I I a hi emaI i s
Keratella quadrata
Lecane tenuiseta
Monostyla sp.
Notholca acuminata
No tholea fo I iacea
Notholca laurentiae
Notholca squamula
Notholca str iata
PIoesoma sp.
Polyarthra dolichoptera
Po lyar thra major
Po lyar thra remata
Polyarthra vulgaris
Synchaeta sp.
Trichocerca cylindrica
Trichocerca multicrinis
Tr ichocerca sp.
-------
270.
Table E
Zooplankton Species List: Lake Huron
-------
271
DIVISION
Ca lanoi da
GREAT LAKES ZOOPLANKTON SPECIES LIST
LAKE HURON
(1983)
TAXON
Catanoid - copepodite
Diaptomus ashlandi
Diaptomus minutus
Diaptomus oregonensis
Di aptomus s i c i I i s
Diaptomus siciloides
Ep ischura lacustr i s
Limnocalanus macrurus
Senecella calanoides
Cladocera
Copepoda
Cyclopoida
Mysidacea
kotifera
Bosmina
Daphnia
Daphnia
Daphnia
Daphnia
Daphnia
Daphnia
Da phn ia
Di aphanosoma
Diaphanosoma
longirostris
catawba
dubia
galaeta mendota
pu I i car i a
retrocurva
schod ler i
sp •
I euc htenber g ianum
sp .
Eubosmina coregoni
Holopedium giboerum
Leptodora K i ndt i i
Polyphemus pediculus
Si 03. crystal I ina
Copepoda Nauplii
Cyclopoid - copepodite
Cyclops bicuspidatus thomasf
Cy c I ops vernal is
Mesocyclops edax
Tropocyclops prasinus mexicanus
Mysis relicta
Ascomorpha sp.
Asplanchna priodonta
Cephal ode I la sp.
Co 1 1 otheca sp.
Conochilus unicornis
Eu ch Ian i s sp.
F i I i na I ong i seta
Gastropus sp.
Cast ropus sty I i f er
Kellicottia longispina
Keratella cochlearis
Keratella cochlearis hispida
Ke rate I la crassa
Ke rate I la ear I inae
-------
272
GREAT LAKES ZOOPLANKTON SPECIES LIST
LAKE HURON
(1983)
DIVISION TAXON
Rotifera Keratella hiemalis
Keratella quadrata
MonostyI a Iunar i s
No tho I ca foil acea
Notholca laurentiae
Notholca squamula
PIoesoma sp•
Polyarthra dolichoptera
Po lyar thra major
Polyarthra remata
PoIyar thra vuI gar i s
Rotifer - soft body
Synchaeta sp.
Trichocerca cylindrica
Tr ichocerca multicrinis
Tr ichocerca sp.
Trichotria pocilium
-------
273
Table F
Zooplankton Species List: Lake Erie
-------
274
GREAT LAKES
DIVISION
ZOOPLANKTON
LAKE ERIE
(1983)
SPECIES LIST
TAXON
Ca lanoIda
CIadocera
Copepoda
CycIopoida
Harpact i co i da
Rotifera
Ca lano i d
0 i ap tomus
D j ap tomus
D i aptomus
D i aptomus
0 i aptomus
Ep i schura
Euryteroora
copepodi te
ash land i
ID inutus
or egonensi s
sic i I is
s i c iIoi des
lacustri s
atfinis
Limnoca lanus macrurus
Senecella calanoides
Bosmina longirostris
Ceriodaphnia lacustris
Ceriodaphnia reticulata
Ceriodaphnia sp.
Chydorus sphaericus
Daphnia catawba
ga laeta mendota
retrocurva
schod ler i
sp.
ecaudi s
leuchtenbergianum
Daphnia
Daphnia
Daphnia
Daphn ia
D i aphanosoma
Di aphanosoma
Eubosmina coregoni
Eurycercus lamellatus
Holopedium gibberum
11yocryptus sp i n i fer
Leptodora k indt ii
S i oa cr ystalIi na
Copepoda NaupI i i
Cyclopoio - copepodite
Cyclops bicuspidatus thomasi
Eucyclops edax
Eucyclops prionophorus
Me socyclops edax
Tropocyclops prasinus mexicanus
Ha rpact i co i da
Alona quadranquIaris
Ascomorpha ecaudis
As comorpha sp.
Asplanchna priodonta
Bdel loi d Roti fera
Brachionus bidentata
Brachionus caudatus
Br ac h i onus sp.
Co I Iotheca sp .
-------
275
GREAT LAKES ZOOPLANKTDN SPECIES LIST
LAKE ERIE
(1983)
DIVISION TAXON
Kotifera Co nochi Ioides sp.
Co nochi I us unicornis
Eu ch Ian i s sp.
F i I i na Iong i seta
Gastropus sp.
Gastropus sty I i fer
Kellicottia longispina
Keratella cochlearis
Ke rate I la crassa
KerateI la ear Iinae
Keratella hi emal is
Keratella quadrats
Lepadel la sp.
Notholca foliacea
Notholca laurentiae
Notholca squamula
PIoesoma sp.
Polyarthra do I ichoptera
Po lyar thra major
Polyarthra remata
Polyarthra vulgaris
Synchaeta sp.
Trichocerca cylindrica
Trichocerca multicrinis
Trichocerca simills
Tr ichocerca sp.
-------
TECHNICAL REPORT DATA
(flcaif rtadlmlrucDom on thr rrirrx btforr complctinf
NO
EPA- 905/3-88-001
3 RECIPIENT'S ACCESSIO*NO
A TIT LE AND SUBT IT Li
Phytoplankton and Zooplankton in Lakes Erie, Huron
and Michigan: 1984
f> REPORT DATE
February 1988
e PERFORMING ORGANIZATION CODE
5GL
7 AUTHOR(S)
Joseph C. Makarewicz
e PERFORMING ORGANIZATION REPORT NO
GLNPO Report No. 3
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Biological Sciences
State University of New York
College at Brockport
Brockport, New York 14420
10 PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
R005772-02
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Great Lakes National Program Office
230 South Dearborn Street
Chicago, Illinois 60604
13. TYPE OF REPORT AND PERIOD COVERED
Final 1984-1985
14. SPONSORING AGENCY CODE
Great Lakes National Program
Office, U.S. EPA, Region V
15. SUPPLEMENTARY NOTES
Paul Bertram, Project Officer
16. ABSTRACT
During the spring, summer and autmn of 1984 and winter of 1985, the structure
of the plankton community in the offshore waters of Lakes Erie, Huron and
Michigan was monitored. By examining changes in the phytoplankton and zooplankton
in relation to water chemistry, evidence was found suggesting little change in
the trophic status of Lake Huron and Michigan while an improvement in the trophic
status of Lake Erie was evident over the past several years. The offshore region
of Lake Michigan is experiencing changes in phytoplankton and zooplankton composition
consistent with nutrient control and top-down control by fish. Even so, the biomass
of phytoplankton and zooplankton and the trophic status of the lake have not changed
significantly. The appearance and establishment of Daphm'a pulicaria in offshore
waters of Lake Huron suggest a change in the forage fish base. With the exception
of the resurgence of Asterione!1 a formosa in Lake Erie, plankton composition has
changed little since the 1960's. However, dramatic reductions in biomass of nuisance
and eutrophic indicator species have occurred. These changes are consistent with
expectations of long-term nutrient control. However, a change in piscivory is
evident that has apparently allowed the establishment of the large caldoceran
Daphm'a pulicaria.
17. KEY WORDS AND DOCUMENT ANALYSIS
•d DESCRIPTORS
Lake Michigan Eutrophication
Lake Huron Great Lakes
Lake Erie Community structure
Plankton
Phytoplankton
Zooplankton
Limnology
18 DISTRIBUTION STATEMENT
Document is available to the Public
through the National Technical Information
Service(NTIS), Springfield, VA 22161
b. IDENTIFIERS/OPEN ENDED TERMS
19. SECURITY CLASS tTMs Report i
20. SECURITY CLASS (This page)
c. COSATl Field/Group
21. NO. OF PAGES
296
22. PRICE
EPA Form 2220-1 (9-73)
* U.S GOVERNMENT PRINTING OFFICE. 1988 543-858
------- |