THE BENTHic MACROINVERTEBRATE POPUIATIONS IN A NEW PUMPED STC‘RAGE RESERVOIR AND THE ADIACENT COASTAL AREAS OF CENTRAL LAKE MCI-“GM Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY GREGORY R. OLSON 1974 THE BE IN A The purpose 0f construction and oper Plant woqu have on 1 adjacent coasta] are. nacroinvertebrate p0 Michigan coastal are and in 1973 during ; zation of the resern inpoundment in Otto he seven P‘a Lake Michi n wer ABSTRACT THE BENTHIC MACROINVERTEBRATE POPULATIONS IN A NEW PUMPED STORAGE RESERVOIR AND THE ADJACENT COASTAL AREAS OF CENTRAL LAKE MICHIGAN By Gregory R. Olson The purpose of this study was to determine what effects the construction and operation of the Ludington Pumped Storage Reservoir Plant would have on the benthic macroinvertebrate populations of the adjacent coastal areas of Lake Michigan and what type of benthic macroinvertebrate populations would develop in the reservoir. The Lake Michigan coastal areas were studied in 1972 before plant operation and in T973 during plant operation. The benthic invertebrate coloni- zation of the reservoir was examined from the initial filling of the impoundment in October, 1972 through one season operation in l973. These benthic populations were sampled by a combination of Ponar grab and artificial substrate sampling. The artificial substrate sampling used modified Hester-Dendy multiple plate and rock basket samplers. The seven major benthic macroinvertebrate groups sampled from Lake Michigan were: Oligochaeta; Ostracoda; Amphipoda; Acari; Chirono— midae; Gastropoda; and Pelecypoda. Chironomid larvae were the dominant group in abundance and regularity from the coastal Lake Michigan areas. Hacroinvertebrate grc were: Nematoda; Hiru‘ and lrichoptera. Single classifi groups indicated that pelecypod populations certain sampling stat least one group's cha population comparison indicated that shallc June and July-Augus t were more variable be reflected the great i Lt) Gregory R. Olson Macroinvertebrate groups collected with less abundance and regularity were: Nematoda; Hirudinea; Mysidacea; Isopoda; Decapoda; Ephemeroptera; and Trichoptera. Single classification analyses of variance of the major benthic groups indicated that oligochaete, ostracod, amphipod, water-mite and pelecypod populations differed significantly between l972 and 1973 at certain sampling stations, with four of the six stations registering at least one group's change. The percentage composition of the benthic population comparisons using Spearman rank correlation coefficients; indicated that shallower Lake Michigan sampling stations, and the May- June and July-August sampling periods had benthic populations which were more variable between l972 and l973. An index of dispersion also reflected the great variation between seasons and stations for each major benthic group. The Ludington Pumped Storage Reservoir was colonized by benthic organisms from the adjacent Lake Michigan area and the major taxa sam- pled were: Oligochaeta; Isopoda; Amphipoda; Acari; Chironomidae; and Gastropoda. The oligochaetes and chironomids were the first two taxa collected, and they became the dominant forms in the reservoir for l973. Benthic groups found with less abundance and regularity were: Hirudinha; Collembola; Ephemeroptera; Trichoptera; Coleoptera; and Ceratopogonidae. Physical and chemical parameters, recorded of the reservoir water, indicated the reservoir benthic organisms were affected by approximately Gregory R. Olson the same water conditions as the adjacent Lake Michigan benthic popu- lations. The chemical composition of the reservoir sediments was analyzed throughout l973 and no significant changes in percentages of total carbon, hydrogen, and nitrogen on a dry weight basis were determined. Detailed identification of the benthic taxa revealed specific distributions and relationships. A large number of immature oligo- chaetes at the sampling stations indicated either an unusual survival of the young or an unusual mortality of the adults. The protective jetties and breakwall area in Lake Michigan has provided microhabitats which have attracted macroinvertebrates not found at the other sampling areas. Gammarus fasciatus Say and g, pseudolimnaeus Bousfield amphipods were found only on the jetties and breakwall in Lake Michigan. The constructional disturbance and operational effect of the Ludington Pumped Storage Plant on the Lake Michigan benthic macroin- vertebrate populations could not be distinguished because this study was started after plant construction had begun. Following the construc- tion and first season of operation, this plant has not had major detri- mental effects on the adjacent Lake Michigan benthic macroinvertebrate communities. _ THE BENTHIC MACROINVERTEBRATE POPULATIONS IN A NEW PUMPED STORAGE RESERVOIR AND THE ADJACENT COASTAL AREAS OF CENTRAL LAKE MICHIGAN By . Gregory RI Olson A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Fisheries and Wildlife I974 ACKNOWLEDGEMENTS I wish to express great appreciation to Dr. P. I. Tack for pro- viding me with this research opportunity, taking a sincere interest in my study, and assisting me in overcoming various obstacles. Apprecia- tion is expressed to the members of my graduate committee, Drs. P. I. Tack (Chairman), R. C. Ball, w. H. Conley, and T. w. Porter for their support and constructive criticism. I thank Dr. T. w. Porter, for his special hints in the identification of the samples and his supportive attitude toward me. I acknowledge Dr. C. R. Liston for designing this study's initial sampling scheme and I extend thanks for his beneficial suggestions in the organization of this manuscript. Special thanks are due my fellow graduate students,tl.w. Armstrong, D. C. Brazo, T. L. Chiotti, L. A. Green, N. G. Duffy, F. R. Hauer, and D. J. Lechel, for helping collect the data. I am grateful to the late Russell Moran for his assistance in the construction of the samplers used in this study. I thank Ms. C. Force for her expertise in preparing the graphics for this manuscript. Appreciation is expressed to Drs. E. L. Bousfield, G. A. Cole, D. R. Cook, K. N. Cummins, L. L. Curry, C. J. Goodnight, D. L. McGregor, R. E. Snyder, and M. G. Hard for their assistance and verification of the taxonomic identification of certain macroinverte» brates from my samples. Acknowledgement is made to Consumers Power Company of Michigan for their funding of this research and to the Department of Fisheries and Wildlife of Michigan State University for providing me with a research assistantship. Finally, I thank my wife, Joanne, for her encouragement, support, and understanding in the past two years; I feel truly fortunate. ii TABLE OF CONTENTS Page INTRODUCTION . . . . . ..................... 1 Purpose of the Study .................. 2 Food Source .................... 2 Environmental Condition Indicator ......... 2 Lake Michigan Research Opportunity ......... 3 Reservoir Research Opportunity ........... 5 Objective of the Study ................. 6 Limitations of the Study ................ 6 Sampling Problems and Schedule ............. 7 Description of the Power Plant ............. 7 LAKE MICHIGAN STUDY ...................... 13 Sampling Stations .................... 13 Methods and Materials .................. 13 Precision of Figure Values ............... 20 Lake Michigan Physical and Chemical Studies ....... 21 Water Temperature Results . . . . . . . . . . . . . 21 Water Transparency Results ............. 28 Water Turbidity Results .............. 31 Water Chemistry Results .............. 31 Lake Michigan Ponar Grab Samples ............ 34 Nematoda ...................... 34 Oligochaeta .................... 34 Hirudinea ..................... 39 Ostracoda ..................... 39 Mysidacea ..................... 39 Amphipoda ..................... 39 Decapoda ...................... 49 Acari ....................... 49 Trichoptera .................... 49 Chironomidae ............ . ....... 59 Gastropoda ..................... 59 Pelecypoda ..................... 59 Percentage Composition of Benthic Macroinvertebrate Populations .................... 7O Dispersion IndeL.of Major Benthic Macroinvertebrate Groups ....................... 96 TABLE OF COh Lake M M R DISCUSSION 0 Statis 1 Negati b Transf Homoge Single Spearm Index Lake H van—IMDI’HOO TABLE OF CONTENTS--continued Page Lake Michigan Artificial Substrate Samples ....... 96 Multiple Plate Samples. . . . . . . . . . . . . . . 96 Rock Basket Samples . . . . . . . . . ....... 101 DISCUSSION OF LAKE MICHIGAN STUDY ............... 104 Statistical Analyses of Lake Michigan Benthic Macro- invertebrates ................... 104 Negative Binomial Distribution of Benthic Macroinverte— brate Population .................. 105 Transformation of Original Data. . . . . ..... . . . 106 Homogeneity of Variances ................ 106 Single Classification Analysis of Variance ....... 106 Spearman Rank Correlation Coefficient (r5) ....... 108 Index of Dispersion ................... 109 Lake Michigan Samples. . . ............... 109 Oligochaeta .................... 110 Ostracoda ..................... 111 Isopoda ...................... 111 Amphipoda . . ................... 112 Acari . . . . . . ................. 113 Ephemeroptera . .................. 114 Trichoptera . . . . ................ 114 Chironomidae .................... 114 Gastropoda ...................... 116 Pelecypoda ................. . . . . 116 RESERVOIR STUDY ......................... 117 Methods and Materials. . . . . . . . . . . . . . . . . . 117 Reservoir Physical and Chemical Studies ......... 121 Weekly Pumping Rates ................ 121 Water Temperature Results . . . . . . . . . . . . . 121 Water Transparency Results ...... . . ..... 121 Water Turbidity Results . . . . . . . . . . . . . . 128 Water Chemistry Results .............. 128 Sediment Chemistry Results ............. 128 Reservoir Ponar Grab Samples . . . . . . . . . ..... 132 Oligochaeta . . . . . . .............. 132 Hirudinea ..................... 132 Amphipoda .................... . 132 Acari ....................... 141 Ephemeroptera ................... 141 Chironomidae. . . . . . . . . . ........... 141 Ceratopogonidae .................. 141 iv TABLE OF CONTENTS--continued Page Reservoir Multiple Plate Samples October, 1972 to April 1973 ........................ 141 Oligochaeta and Chironomidae ............ 141 Reservoir Multiple Plate Samples April to August, 1973 . 145 Oligochaeta .................... 145 Hirudinea ..................... 145 Isopoda ...................... 152 Amphipoda ......... , ............ 152 Acari ....................... 152 Collembola ..................... 152 Ephemeroptera ................... 152 Trichoptera .................... 158 Coleoptera ..................... 158 Chironomidae .................... 158 Gastropoda ..................... 158 Reservoir Multiple Plate Samples June to September, 1973 158 Oligochaeta .................... 158 Isopoda ...................... 162 Gastropoda ..................... 162' Reservoir Multiple Plate Samples July to October, 1973 . 162 Oligochaeta .................... 162 Isopoda ...................... 162 Gastropoda ..................... 162 Reservoir Multiple Plate Samples August to November, 1973 ........................ 166 Isopoda ...................... 166 Amphipoda ..................... 166 Acari ....................... 166 Gastropoda ..................... 166 Reservoir Rock Basket Samples on Scour Protection Area . 170 Reservoir Benthic Macroinvertebrate Colonization and Development .................... 170 Reservoir Core Samples ................. 177 DISCUSSION OF RESERVOIR STUDY ................. 179 Reservoir Benthic Macroinvertebrate Colonization . . . . 179 Oligochaeta and Chironomidae ............ 179 Isopoda ...................... 180 Amphipoda ..................... 181 Acari ....................... 182 Gastropoda ..................... 182 Pelecypoda ..................... 182 TABLE OF CONTENTS--continued Page SUMMARY AND CONCLUSIONS. ................... 183 Lake Michigan ...................... 183 Reservoir ........................ 185 Reservoir Impact on Lake Michigan Benthic Macroinverte- brates ....................... 186 APPENDIX ........................... 187 LITERATURE CITED ....................... 216 vi TABLE 10. 11. LIST OF TABLES . Description of Lake Michigan Sampling Stations ...... . Secchi Disc Reading Descriptive Statistics from Lake Michigan Sampling Stations During 1972 .......... . Secchi Disc Reading Descriptive Statistics from Lake Michigan Sampling Stations During 1973 .......... . Surface Turbidity Measurement (Formazin Turbidity Units) Descriptive Statistics from Lake Michigan Sampling Sta- tions During 1972 ..................... . Surface Turbidity Measurement (Formazin Turbidity Units) Descriptive Statistics from Lake Michigan Sampling Sta- tions During 1973 ..................... . Taxa and Relative Abundance of Lake Michigan Benthic Macroinvertebrates in 1972 and 1973 Ponar Grab Samples (192 Samples) ....................... . Taxa and Number of Oligochaeta in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampling Stations (Composition for Each Station on Each Sampling Day is a Three«Samp1e Total .......................... . Number of Ostracoda, Species of Candona, in the 1972 and 1973 Ponar Grab Samples from Lake M1c51gan Sampling Sta- tions (Three- -Samp1e Total for Each Station on Each Sampl— ing Day) ......................... . Number of Amphipoda, Pontoporeia affinis (Lindstrom), in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampl- ing Stations (Three-Sample Total for Each Station on Each Sampling Day) ....................... Taxa and Number of Acari in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampling Stations (Composition for Each Station on Each Sampling Day is a ThreevSample Total .......................... Taxa and Number of Chironomidae in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampling Stations (Compoo sition for Each Station on Each Sampling Day is a Three« Sample Total). .................. . . vii Page 14 29 30 32 33 35 4O 45 50 54 60 LIST OF TABLES--continued TABLE 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. Taxa and Number of Gastropoda in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampling Stations (Composition for Each Station on Each Sampling Day is a Three-Sample Total .......................... Taxa and Number of Pelecypoda in 1972 and 1973 Ponar Grab Samples from Lake Michigan Sampling Stations (Composition for Each Station on Each Sampling Day is a Three—Sample Total .......................... Spearman Rank Correlation Coefficients for Comparison of Lake Michigan Benthic Macroinvertebrate Groups' Percentage Composition of Population Between 1972 and 1973 ...... Dispersion Index for Major Benthic Macroinvertebrate Taxa from Lake Michigan 1972 and 1973 Ponar Grab Samples. . . . Taxa and Relative Abundance of Lake Michigan Benthic Macroinvertebrates in 1972 and 1973 Multiple Plate Samples (6 Samples) ........................ Taxa and Relative Abundance of Lake Michigan Benthic Macroinvertebrates in 1972 and 1973 Rock Basket Samples (2 Samples) ........................ Mean (i), Variance (52), and Excessive Variance or "Clumping" (k) of Lake Michigan Benthic Macroinvertebrate Major Taxa from the Combined Six Stations and Two Seasons (Ponar Grab Samples) ................... Surface Turbidity Measurement (Formazin Turbidity Units) Descriptive Statistics from Reservoir Sampling Stations During 1973 ........................ Taxa and Relative Abundance of Reservoir Benthic Macro« invertebrates in 1973 Ponar Grab Samples (42 Samples). . . Taxa and Number of Oligochaeta in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three-Sample Total) ........... Taxa and Number of Amphipoda in Reservoir Ponar Grab and Multiple Plate Samples for 1973 (Ponar Grab Composition for Each Station on Each Sampling Day is a Three«Samp1e Total) .......................... viii Page 66 71 75 97 98 102 107 129 133 137 140 LIST OF TABLES-—continued TABLE 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. Taxa and Number of Acari in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three-Sample Total) ............... Taxa and Number of Chironomidae in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three-Sample Total) .......... Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in October, 1972 to April, 1973 Multiple Plate Samples (3 Samples) ................ Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in April to August, 1973 Multiple Plate Samples (18 Samples) ................... Taxa and Number of Oligochaeta in 1973 Multiple Plate Samples from Reservoir Sampling Stations ......... Taxa and Number of Acari in 1973 Multiple Plate Samples from Reservoir Sampling Stations ............. Taxa and Number of Chironomidae in 1973 Multiple Plate Samples from Reservoir Sampling Stations ......... Taxa and Relative Abundance of Reservoir Benthic Macro— invertebrates in June to September, 1973 Multiple Plate Samples (6 Samples) ................... Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in July to October, 1973 Multiple Plate Samples (6 Samples) ................... Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in August to November, 1973 Multiple Plate Samples (5 Samples) ................... Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in 1973 Rock Basket Samples (15 Samples). . Taxa and Number of Reservoir Benthic Macroinvertebrates in Core Samples from September 1, 1973. . ........ ix Page 142 143 144 146 151 155 156 159 163 167 171 178 FIGURE 1. 10. LIST OF FIGURES Sampling schedule of Lake Michigan and Ludington Pumped Storage Reservoir for 1972 and 1973 ........... . Diagram of the Ludington Pumped Storage Plant showing sampling stations (1-6), and offshore protective rock jetties and breakwall ................ . Sampling stations in the Ludington Pumped Storage Reser- voir, and on the protective rock jetties and breakwall in Lake Michigan (X's = rock basket samplers) ..... . Modified Hester-Dendy multiple plate sampler and rock basket sampler ..................... . Average surface and bottom water temperatures at Lake Michigan sampling stations during 1972 ......... . Average surface and bottom water temperatures at Lake Michigan sampling stations one, three, and five during 1973 .......................... . Average surface and bottom water temperatures at Lake Michigan sampling stations two, four, and six during 1973 .......................... . Oligochaeta seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day) ...................... . Ostracoda seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day).' ..................... Amphipoda, Pontoporeia affinis (Lindstrom), seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day) . . ...... Page 11 16 18 23 25 27 43 47 52 LIST 0? Fl FIGURE 11. 12. 13. 14. 17. 18. 20. Acai stai Poné day. Chir samc of t sanp Gast samp of t samp pQIEl samp of tl samp' - Compe tions one a - Comps Popul stati COMpe brate IVOm COMpa IIOnS three - Compa PODul Staci Compa brate FFOm LIST OF FIGURES--continued FIGURE 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Acari seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day ........................... Chironomidae seasonal distribution at Lake Michigan sampling station for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day) ...................... Gastropoda seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day) ...................... Pelecypoda seasonal distribution at Lake Michigan sampling stations for 1972 and 1973 (values are average of three Ponar grab samples taken at each station each sampling day) ...................... Comparison of May-June benthic macroinvertebrate popula- tions of 1972 and 1973 Ponar grab samples from stations one and two ....................... Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations one and two .................. Comparison of September-October benthic macroinverte- brate populations of 1972 and 1973 Ponar grab samples from stations one and two ................ Comparison of May-June benthic macroinvertebrate popula- tions of 1972 and 1973 Ponar grab samples from stations three and four . . . . . . . . . . . . . . . . . . . . . Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations three and four ................. Comparison of September-October benthic macroinverte- brate populations of 1972 and 1973 Ponar grab samples from stations three and four .............. xi Page 57 64 68 73 78 8O 82 84 86 88 laur, . LIST OF FIE FIGURE 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31 Corps tions five Compa brat: from Comp. DODU stat Rese the Hate Stor indi unit AVEr Voir Aver stat Stat AVEr Sdfip Samp 0119 the DIne V01r pOna ' 0119 rese molt LIST OF FIGURES--continued FIGURE 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. Comparison of May-June benthic macroinvertebrate popula- tions of 1972 and 1973 Ponar grab samples from stations five and six ...................... Comparison of September-October benthic macroinverte- brate populations of 1972 and 1973 Ponar grab samples from stations five and six ............... Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations five and six .................. Reservoir core sampling locations on the clay rim near the bottom of the embankment . ............. Water volume pumping capability of the Ludington Pumped Storage Reservoir for each week in 1973 (numbers 1-6 indicate the first operational date of each pump-turbine unit) .......................... Average surface and bottom water temperatures at reser- voir sampling stations during 1973 . . ......... Average secchi disc readings at Lake Michigan sampling stations three and five, and at reservoir sampling stations during 1973 .................. Average surface turbidity measurements at Lake Michigan sampling stations three and five, and at reservoir sampling stations during 1973 .............. Oligochaeta and Chironomidae seasonal distribution in the reservoir for 1973 (values are average of the total nine Ponar grab samples taken each sampling day) . . . . Amphipoda and Acari seasonal distribution in the reser- voir for 1973 (values are average of the total nine Ponar grab samples taken each sampling day). . . . . . . Oligochaeta and Acari seasonal distribution in the reservoir for 1973 (values are average of the total six multiple plate samples taken each sampling day) ..... xii Page 91 93 95 120 123 125 127 131 136 139 150 LIST 0 FIGURE 32. 33. 34. F FIGURES-—continued Chironomidae, Amphipoda and Isopoda seasonal distribu- tion in the reservoir for 1973 (values are average of the total six multiple plate samples taken each sampling day) .......................... Oligochaeta, Chironomidae and Acari seasonal distribu- tion in the reservoir for 1973 (values are average of the total four rock basket samples taken each sampling day) .......................... Percentage composition seasonal trends of reservoir benthic macroinvertebrates from three months in 1973 Ponar grab and multiple plate samples (number/m2 is the average total number organisms each sampling day). . . . xiii Page 154 174 176 The Depe University, tl Consumers ROM 131 Study to a electric Plant determine What PhI’Sical parap transparency a reservoir. C1 dl'Ssolved $011 INTRODUCTION The Department of Fisheries and Wildlife of Michigan State University, through Dr. Peter I. Tack, contracted in 1971 with Consumers Power Company of Michigan to conduct a sixfiyear environmen- tal study to assess the impact of its Ludington Pumped Storage Hydro- electric Plant on the adjacent coastal Lake Michigan areas and to determine what aquatic populations would colonize the reservoir. Physical parameter studies of air and water temperatures, and water transparency and turbidity would be made in Lake Michigan and the reservoir. Chemical studies of pH, dissolved O , alkalinity, and 2 dissolved solids would also be made in Lake Michigan and the reservoir. The aquatic organism population studies would include surveys of periphyton, phytoplankton, zooplankton, benthic invertebrates and fish. Dr. Peter I. Tack, Fisheries and Wildlife Department of Michigan State University, is the supervisor of this research project and Dr. Charles R. Liston, also of Michigan State University, is the field coordinator of these environmental studies. The field data were col- lected by an average of four graduate research assistants with a boat captain. :3..uzr-u—;r ; ‘99."— The be Pumped Stora Michigan is Food Source Benthi are an essen Organism pOp other GQUati Environn r ‘--———ffll£i The de- t1°" a"d pos: coastal area: the benthic ; in and Out 0. istjc enV1ror 1" CornPosr‘tn rather than I brates pr0vi< asuatjc Area ”Wes in u Hflhm. 1967) Purpose of the Study The benthic macroinvertebrate population study of the Ludington Pumped Storage Reservoir and the adjacent coastal areas of Lake Michigan is warranted for several reasons. Food Source Benthic macroinvertebrates, sometimes termed fishvfood organisms, are an essential food source in aquatic ecosystems. The benthic organism population composition and abundance influence and support other aquatic populations. Environmental Condition Indicator The determination of the environmental effects of the construc« tion and possibly the operation of the reservoir on the adjacent coastal areas of Lake Michigan can be evaluated most effectively by the benthic macroinvertebrate populations. Fish and plankton movement in and out of these areas makes them less reflective of the character- istic environmental conditions. The benthic organism population changes in composition and abundance in relation to the environmental conditions rather than by temporarily leaving the area. Benthic macroinverte- brates provide a good indicator of the environmental conditions of an aquatic area by their particular population composition and by the changes in their relative abundances (Simpson, 1949; Gaufin, 1956; Hilhm, 1967). Th knowledg research investig samples to 117 n vertebra abundant study wh COMDrehe brates. C011eCte the domi Th brates i benthjC Powers, dominate MichIgan Herrlnst IbURdanc. Michigan He‘ bottom d1 the "19hr Lake Michigan Research Opportunity This study is also warranted because of the relatively meager knowledge of Great Lakes benthic populations. Most of this benthic research has been accomplished in the past several decades. An early investigation made by Stimpson (1870) reported findings from dredge samples taken in southern Lake Michigan near Chicago in water from 27 to 117 m depth. Eggleton (1936 and 1937) found the deep-water macro- vertebrates, Pontoporeia sp., Tubificidae, and Sphaeriidae, the most abundant benthic organisms from samples taken in 1931 and 1932. This study which used samples from many areas of Lake Michigan was the first comprehensive investigation of the Lake Michigan benthic macroinverte— brates. Merna (1960) studied Lake Michigan benthic invertebrates collected from 1951 to 1955, finding Pontoporeia affinis (Lindstrom) the dominant organism. The effect of the St. Joseph River on the benthic macroinverte- brates in the adjoining area of Lake Michigan was compared with the benthic community off Little Sable Point south of Ludington (Cook and Powers, 1964). Powers and Robertson (1965) found that amphipods dominated the benthic macroinvertebrates in the northern part of Lake Michigan and oligochaetes dominated in the southern part. Henson and Herrington (1965) found relationships between the sediment type and abundance of different species of Sphaeriidae (Mollusca) of Lake Michigan in the Straits of Mackinac. Wells (1968a and1968b) concluded that _P_. affinis burrows into the bottom during the daytime and migrates into the water column during the night. Robertson and Alley (1966) investigated the deep-water macrobenthos using methods similar to those of Eggleton for compara- tive purposes. They found more Pontoporeia sp., oligochaetes, and Sphaeriidae in 1964 than Eggleton had 30 years earlier. The species diversity of sphaeriids decreases with increasing depth in Lake Michigan (Robertson, 1967). Hiltunen (1967) corrected the taxonomic identifica- tion of Lake Michigan oligochaetes which had been incorrectly grouped as Tubificidae in several previous studies. Alley (1968) found 3, affinis distributed on the bottom in rela- tion to water depth with maximum concentration at 35 m. The zonation and distribution of benthic macroinvertebrates in the coastal zone of southeastern Lake Michigan were investigated by Mozley and Garcia (1972), who found a clear gradient in total abundance and species compo- sition. Modlin and Gannon (1973) investigated the ecology and dis- tribution of water-mites in the St. Lawrence Great Lakes. They found species of Lebertia and Hygrobates to predominate their samples. Armstrong (1973), a fellow graduate research assistant on the Ludington Pumped Storage Plant research project, found chironomids were the major food item eaten by round whitefish, Proposium cylindraceum (Pallas), in the adjacent Lake Michigan areas. Snails, leeches, and crayfish were other food items. Brazo (1973), another fellow graduate assistant on this project, found amphipods were the major food item of the yellow perch, Perca flavescens (Mitchill), from 135-235 mm total length; and fish and crayfish were the major food items in larger perch. Reservoir Research Opportunity This benthic study also provides an opportunity to determine what benthic macroinvertebrates would colonize the reservoir from a large inland body of water like Lake Michigan. Most reservoir macro- invertebrate studies have dealt with colonization in newly constructed river reservoirs. The Russian research and literature have covered large river reservoirs with appreciable currents passing the length of the basin. Ozhegova (1962) studied the pattern of macroinvertebrate colonization in Kairak-Kumsk Reservoir, a Russian river reservoir, during the first year of its existence. Sokolova (1963) made a similar study of Mozhaisk Reservoir, during the first year of its existence. These two studies exemplify the macroinvertebrate reservoir research in the literature. Because the emphasis in the Russian literature has been on large river reservoirs with appreciable currents, direct com- parison with a pumped storage reservoir is inappropriate. Fragmentary information on the macroinvertebrate populations in North American reservoirs is available from studies of established older reservoirs. Nursall (1952) studied the development of the benthic fauna in a mountain reservoir in Alberta from May, 1947, shortly after the initial filling of the impoundment, through June, 1949. Later, Fillion (1967) studied the macroinvertebrate community of this same Alberta reservoir from 1960 to 1962 and compared his findings with those of Nursall's earlier study. Again, these two studies cannot be directly compared with pumped storage reservoirs which have a different flow pattern than river reservoirs. Objective of the Study The objectives of this study were to determine what effects the construction and operation of the Ludington Pumped Storage Plant would have on the adjacent Lake Michigan benthic populations and to determine the colonization rate of benthic macroinvertebrates in the new reservoir. The Lake Michigan segment of this study will compare the data from May to October, 1972 (pre-operational), to data taken during the first year of plant operation, May to October, 1973. The macroinverte- brate colonization of the reservoir was studied from the initial filling of the reservoir in October, 1972, through November, 1973. The reservoir benthic communities that developed will be compared to the benthic popu- lations sampled from the adjacent Lake Michigan study areas. Limitations of the Study The construction of this plant was started several years before these environmental studies began in the adjacent coastal Lake Michigan areas. Thus, the study was conducted in an altered or disturbed area. Because little baseline data is available on the pre-constructional environmental conditions of this area, changes in the benthic population from 1972 to 1973 may have resulted from the construction disturbance rather than plant operation. The distinction between construction and operation disturbance of the benthic populations is important. However, the lack of baseline data on the benthic macroinvertebrates before construction makes it difficult to assess whether the operation of the plant is affecting these populations. Sampling Problems and Schedule Lake Michigan is very difficult to sample because of recurrent high wind and wave conditions, and sampling sites were often inaccess- ible for field work. These wind and wave conditions particularly affected the macroinvertebrate sampling because relatively calm condi- tions are necessary to operate the Ponar grab-sampler and to collect the artificial substrate samplers. The resulting incomplete sampling schedules make comprehensive statistical evaluations of the benthic macroinvertebrate populations difficult. The time table of the Lake Michigan and reservoir sampling of this study (Figure 1) shows the relationships and durations of the different sampling methods used in the two seasons. Description of the Power Plant The Ludington Pumped Storage Hydroelectric Plant was constructed jointly by the Consumers Power and Detroit Edison companies of Michigan for the purpose of assuring their clientele an adequate supply of elec- trical power at times of maximum energy demand. This plant, the largest of its kind in existence with the reservoir approximately 4.0 km long and averaging 1.2 km wide, is located on the shore of Lake Michigan 6.4 km south of Ludington, Michigan (Figure 2). The pumped storage reser- voir plant functions by pumping water from Lake Michigan up into the reservoir which has a maximum water level of 106.7 m above the Lake Michigan water level. The reservoir is filled with water by pump- turbines, using electricity from existing electrical energy reserves for .mNmF vcm mum, com Lwo>gmmmm mamgogm uwQE:a :oumcw834 vcm :mmw;u_z axe; we mpsvmcum mcwpasmm .P mczmwm p mg=m_m L >81 T I .0! 18¢ 1: >1F "a )( _g '0 «.1 P» 1., ,.l.l ”’ ,- n .1. "0 x a vN x x I p x N. x O. >024 H00 Baum .034 mzma >32 «use .mmu .241momo .>OZ Poo Hawm - .034 th_ >157 MISQMIom ozjmim mhz5mo<2 21.—hum wzsa >42 HIOAUBSBU . NV9IHOIW BXV'I . _‘ .21. 10 >315 A . 'n?&& ’1 Figure 2. Diagram of the Ludington Pumped Storage Plant showing . sampling stations (1-6), and offshore protective rock -... ;& jetties and breakwall. 11 SAMPLING STATIONS Ludington Pumped Stotorasl‘1 P'°1°°' WW LUDIN v ./.. //; 1 P0,. ”grout”. N Lalo ling ‘ock L S e e 0 '\ § Q Q 1 F.-. . Q abs: Lalo J Figure 2 c5 pumping during low by HBIQT flowing ba' peak demand periods= Six Francis-t, between Lake Michig which are 8.7m in . end. Two large roc Michigan plant faC' compacted clay, ex diameter limestone voir has an aSpha‘ in maximum depth hectares when fui meters of Water, We" 99neration m in One day, W kw are pmducedi ”°"‘1"dUStr1a1 . 12 pumping during low energy demand times. Electrical generation occurs by water flowing back down to Lake Michigan turning turbines during peak demand periods. Six Francis-type reversible pump-turbines transfer the water between Lake Michigan and the reservoir through six large penstocks which are 8.7 m in diameter, tapering to 7.3 m at the Lake Michigan end. Two large rock jetties and a breakwall protect the onshore Lake Michigan plant facilities. The reservoir bottom consists mainly of compacted clay, except for a scour protection area composed of 0.3 m diameter limestone rocks in front of the intake structure. The reser- voir has an asphalt-lined embankment averaging 32.9 m in height, varies in maximum depth from 32.0 to 34.1 m, has a surface area of 340.8 hectares when full, and has a maximum volume of 102 million cubic meters of water. Of this total volume, 64 million cu m are usable for power generation and the surface level may be lowered by 12.2 to 15.2 m in one day. When all six units are generating, a maximum of 1,872,000 kw are produced, enough to meet the needs of a 2.5 million population non-industrial city for eight hours. The Lake Mi page 11. and desc The benthig grab-sampler, moc baskEt Siimplers . of Lake Michigan monthly basis at October in 1972 a was placed at eai two months. The SampIed by 16 roc Storms. amp] lng FISUT‘Q 3. The "‘UItipl by Hester and Den bGard plateS SDac 1.12 m2 ( LAKE MICHIGAN STUDY Sampling_Stations The Lake Michigan sampling stations are shown in Figure 2, on page 11, and described in Table l, on the following page. Methods and Materials The benthic macroinvertebrate samples were collected by a Ponar grab-sampler, modified Hester-Dendy multiple plate samplers, and rock basket samplers to analyze the different habitats in the coastal areas of Lake Michigan. Triplicate Ponar grab samples were taken on a monthly basis at the six Lake Michigan stations from May through October in 1972 and 1973. On May 9, 1973, one multiple plate sampler was placed at each of the six Lake Michigan stations and sampled after two months. The offshore protective rock jetties and breakwall were sampled by 16 rock basket samplers placed May 21, 1973, and two were removed after three months. The other samplers were lost because of storms. Sampling sites on these offshore structures are shown in Figure 3. The multiple plate samplers, a modification of the one described by Hester and Dendy (1962), were constructed of fourteen 20 cm2 hard- board plates spaced vertically along a metal rod having a total surface area of 1.12 m2 (Figure 4). Rock basket samplers were constructed of 13 .. 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The basket samplers were 68 cm in height, weighed approximately 22.5 kg, and had a total substrate surface area of 0.76 m2. The macroinvertebrates were separated from the sediments and sam- plers by being washed in a tub and poured through a U. S. Standard No. 30 sieve. Organisms were separated into major groups, counted, preserved in 95 percent alcohol, identified and then expressed in number of individu- als/m2 using appropriate conversion factors: 18.9 for Ponar grab-sampler; 0.89 for multiple plate samplers; 1.32 for rock basket samplers. Identifications were made using several taxonomic keys: oligo- chaetes (Hiltunen, 1973); ostracods, isopods, mysids, watervmites, gastropods and pelecypods (Pennak, 1953); amphipods (Pennak, 1953 and Bousfield, 1958); ephemeropteran nymphs and trichopteran‘larvae (Pennak, 1953; Day, 1971; Denning, 1971); Chironomid larvae (Roback, 1957 and Mason, 1973). These benthic organism groups, except oligochaetes and Chironomid larvae, were individually identified. The raw data from the Lake Michigan Ponar grab and artificial substrate sampling are appended. The oligochaetes were subsampled when more than 30 individuals were present in one sample; the majority of the samples had less than 30 individuals/sample. A random subsample of one—half of each larger sample was identified, and the results were applied to the entire sample proportionately. The oligochaete specimens were processed, mounted and identified according to Hiltunen (1973). 20 Identification of the chironomid larvae involved grouping the specimens according to size, color and macroscopic morphological features. Representatives of each of the groupings were mounted and identified with the number of individuals in each group recorded on the slide. All the members of each grouping were given the same identification as the representative slide; more than one representa« tive slide was made of a grouping to check the homogeneity of the grouping. Precision of Figure Values The organism group percentages on the figures have a 0.01 level of precision because of the conversion factors used for organisms/m2. Incidental macroinvertebrates in the composition of the population would be eliminated in the figures if the percentages were rounded to the 0.1 level and these incidental organisms should be represented to accurately reflect the entire population composition. 21 Lake Michigan Physical and Chemical Studies Water Temperature Results Surface and bottom temperature readings made during 1972 and 1973 are shown in Figures 5, 6 and 7. Because temperatures at similar depth stations varied only slightly on all the 1972 sampling dates, data from stations one, three, and five (12-14 m depth) and from sta- tions two and six (6-8 m depth) were combined and average values were calculated (Figure 5). Station four (24 m depth) water temperatures were plotted separately (Figure 5). The 1973 Lake Michigan surface and bottom temperatures were plotted for each station (Figures 6 and 7). Temperatures were homothermous and lowest April 3, 1972 (2.0-2.5 C) and April 13, 1973 (3.2 C). Water temperatures increased very irregularly to maximum values August 28, 1972 (20 C) and August 13, 1973 (23 C). The 1973 season had warmer minimum and maximum water temperatures with the rate of change more rapid. Bottom temperatures lagged behind surface temperatures especially at station four in both seasons. Temperatures at station four showed indications of varying independently from the other stations; temperatures increased from May 23 to June 2, 1972 at both surface and bottom depths at all stations except station four where the surface temperature decreased from 10.8 to 6.9 C (Figure 5). The erratic water temperature data during the warming period of both seasons was caused mainly by the upwelling and displacement of colder, deeper water. The bottom temperatures in the Lake Michigan 22 .mump mcwgzo mcowumpm mgr—aEmm :mmwcuwz mxmg pm megsumgmaEmw gape; Eoupon use mumecsm mmmcm>< .m mesmwm 23 m mgsmEm ¢u02m>oz munchoo cwozubuwm .5334 >42. mid. >43 .534 .. ._. u—d- dd —qdd. —: :4—4. L j d—.. :: 4 52.8 II. 885m L «km. .2350: 9.4.. .v 3:03 $0 I ‘lxI-UOOODK . III s.— s\\\\\ III/II \\\\I I” .s no \\ Io -\ \/ .. ./ x .1 52.8 I \s 1’11... 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O. 00 . . 7 2. \ I... 20.5.00 . n. _ /. \/ \\ I 344200 .. \\ n5. 240.20.: 9.4.. .0 20:45 . 0 m E» r : E z: r _F .E — F b F r LE: PP - p 0 II 3/ 11... l\ .. m \\ Ill _\ I. 411/ s \11). x 4. _ 4 _ x I \ \/\ __ a _ — x / \a \\ L0_ 00 s — a _ — \ /’\\ (\ _ . . . 4 .1 20:00 . . r I 00428 . n. .. \\\ .20. 240.20.: 9.4.. .4 20:45 .ON shallow c were neve cluded tl with onsl winds C01 (1942 an. cycles i1 Th1 collectil to 6PM: temPETatl at all tl Se and no t Secchi d in Table Tr est area In 1972 Static”S two 36ts Dredging caused v1 depending 28 shallow coastal waters (less than 22-27 m) near Saugatuck, Michigan, were never stable for any length of time (Wells, 1968). Wells con- cluded that winds were responsible for the erratic water temperatures with onshore winds increasing the depth of warm water and offshore winds causing colder water to enter the inshore coastal areas. Church (1942 and 1945) presents a comprehensive account of temperature cycles in Lake Michigan. The 1972 water temperatures from September to the end of the collecting season in November decreased at a generally constant rate to approximately 7 C at all stations on November 15, 1972. The 1973 temperatures from this period of the year were erratic with an increase at all the stations in October. Water Transparency Results Secchi disc readings fluctuated at all stations in both seasons and no trends could be detected. The descriptive statistics of the secchi disc measurements at all stations for 1972 and 1973 are listed in Tables 2 and 3 respectively. Transparency readings at stations two and six (6-8 m), the shallow- est areas, ranged from 0.9 to 5.3 m in 1972 and 0.7 to 5.2 in 1973. In 1972 these stations had greater variation in the data than the other stations. However, there was no significant correlation between the two sets of data indicating that the variation was independent. Dredging of the area between the jetties during construction in 1972 caused visible amounts of turbid water to move either north or south depending on the water currents; this might explain the independent variation between the two stations. 29 xm.44 Em.mm Em.om Ew.mm &—.mm &_.~m sowpuwsu> mo usmwowwwmou mm; 3; No; om; mo; 3.” s052>0u usuusfim 04; mm..— 40; m4; 3; :4; 00:222. NTN mm.m mm... 006 afim ow.m sum: m.m-m.o “$-44 QT...“ 06-44 m.m-m.o 0.01m; mmsmm u m 4 m N _ uwpmwpmpm Nan msvsuo msoEuuum mstsEum sumwsusz 020. E02» mumumwpupm 0>200220m00 mswuumm omwo wsoumm .N mpnuh mnmp mchao mcopucum mcw_QEcm :cmwxuwz 0204 E024 mumumfiumum m>muQmLUme mcmbmmm Ume mQUUmW .M mkams 3O Em.m4 0o.wm 0m.mm 0m.mm 04.4m 00.0m sowpmwsu> 40 02040444000 0... 00.. 00.. 00.. 40.. 00.. 00.004004 02040000 00.. 0... 04.. 44.4 00.. 04.4 00004.40 0.0 0.0 ..4 0.0 2.0 0.0 000: 0.0-0.0 0 0-0.0 0.0-0.0 0.0-0.. 0 0-0.. 0.0-0.. 00000 04 .4 04 .4 04 _4 0000400. 40 200002 .0 0 4 0 0 4 040000000 00.0000 MNmF mswsso 0:04000m msPFQEmm smmwsuwz 0200 E024 muwumwpmpm 0>000020000 mswummm 0000 _suumm .m 04000 31 At stations one, three, and five (12-14 m depth), secchi disc measurements ranged from 1.4 to 6.9 m in 1972 and from 0.9 to 5.9 m in 1972, indicating decreased transparency. Cook and Powers (1964) reported secchi disc measurements of 2.5 to 5.0 m in Lake Michigan near Benton Harbor at depths corresponding to stations one, three, and five. Station 4 (24 m depth), the deep station, averaged 4.87 m in 1972 and 4.1 in 1973 with 3.1 to 7.8 m and 2.2 to 7.6 m ranges respec- tively. Station 4, approximately 2.4 km farther out into Lake Michigan than are any of the other stations, is the clearest water station being least influenced by shore erosion or the dredging activities although dredged materials from the plant were dumped near this station. Secchi disc readings of 4.5 to 7.0 m at a similar depth were measured in southern Lake Michigan (Cook and Powers, 1964). Water Turbidity Results Turbidity measurements were first taken on June 29, 1972 and were measured in formazin turbidity units. Turbidities ranged from 0.3 to 2.4 in 1972 (Table 4) and from 0.3 to 17.0 in 1973 for surface waters (Table 5). Water Chemistry_Results Wind action caused extensive mixing in these coastal areas during 1972 and 1973, and the chemical parameters were within the following ranges at all stations: pH 7.4-8.8; dissolved O2 8.7-15.0 ppm; .alkalinity 98-136 ppm; dissolved solids 151-202 ppm (Liston and Tack, 1973; Liston, 1974). These measurements were determined by standard 32 .mump .mm 2000000 u...0 .w smuEwwsmm .00 400004 .4 000004 .44 xpsu .00 0s0u ”mmpmu 0s4204404 020 so smxmp musmEmsummmzw 0.4 0.0 0.0 0.0 0.0 0.0 :00: 0.0-0.4 0.0-4.0 0.0-m.o 0.4-0.0 4.0-0.0 0.4-0.0 00:00 0 o o u 0 so 00s4u002 40 smnEuz u 0 4 m N 4 04004pmpm sowpmpm 000. 000.00 00000000 000.0200 000.2002 0200 E024 muwpmwpmpm m>400420000 4000s: >04u4020H s000Esosv psmEmsummmz Auwuwnszp 000420m .4 04004 33 .mm0p .00 0000000 00 £000 0000< 2000 c0000 0000500000020 00.00 00.00 00.00 00.00 00.000 00.00 00000000) 00 00000000000 00.0 00.0 00.0 00.0 00.0 00.0 000000>00 00000000 00.0 00.0 00.0 00.0 0.0 00.0 0000000> 00.0 00.0 00.0 00.0 00.0 00.0 000: 0.0-0.0 0.0-0.0 0.0-0.0 0.0-0.0 0.00-0.0 0.0-0.0 00:00 00 00 00 00 00 000 00000000 00 000002 0 0 0 0 0 0 000000000 0000000 0000 000000 00000000 00000500 0000000: 0000 5000 0000000000 0>000000000 0000:: 000000000 000030000 0005000000: 000000000 0000000 .0 00000 anaTytica among sta did not a The first sea macroinve areas of Chironomi TarTy in- The Tarity fr: HYSTdacea The numerica] brates of NEm statiOns’ ””16 th 03% "ant Oligo smal], Tmm 34 analytical methods. Because these chemical parameters were similar among stations and consistent throughout both seasons, they probably did not affect the benthic macroinvertebrates. Lake Michigan Ponar Grab Samples The study of the Lake Michigan coastal areas had 90 samples the first season and 102 samples the second season. Seven predominant macroinvertebrate groups were sampled from the Lake Michigan coastal areas of this study: Oligochaeta; Ostracoda; Amphipoda; Acari; Chironomidae; Gastropoda; and Pelecypoda. These groups were found regu- larly in the samples from both seasons. The macroinvertebrate groups found in less abundance and regu- larity from the coastal sampling areas were: Nematoda; Hirudinea; Mysidacea; Isopoda; Decapoda; Ephemeroptera; and Trichoptera. The Lake Michigan coastal sampling area study will compare the numerical abundance and taxonomic composition of the macroinverte- brates of the l972 season with those of the 1973 season. Nematoda Nematodes were found occasionally at the Lake Michigan sampling stations, but the sampling methods used probably did not efficiently sample them because of their small size. Oligochaeta Limnodrilus sp., Peloscolex sp. and Tubifex sp. were the predomi- nant oligochaetes found at the Lake Michigan sampling stations. Many small, immature forms were found in the samples along with eight \mhe‘hb’tfi Table 6. Relative l macroinver R (r C (c Nematoda Annelida 011g leL Arthropoda Eucr 35 1F£1ble 6. Taxa and Relative Abundance of Lake Michigan Benthic Macro- invertebrates in l972 and l973 Ponar Grab Samples (l92 Samples) Ftealative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% A (abundant) = 5l-75% C (common) = 26-50% VA (very abundant) = 76-l00% Nema toda R {\rInelida Oligochaeta A Plesiopora Naididae Stylaria sp. Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Hirudinea R Arthropoda Eucrustacea Ostracoda R Podocopa Cypridae Candona rawsoni Tressler Q, inopinata Furtos g, aggti_Hoff g, cf;*acutula Delorme continued ———_____ *u ' . . cf,9 means “Similar to" 36 1'Eible 6--continued Malacostraca R Mysidacea Mysidae Mysis oculata relicta (Loveh) Amphipoda C Haustoriidae Pontoporeia affinis (Lindstrom) Decapoda R Arachnoidea Acari C Lebertiidae Lebertia sp. Hygrobatidae Hygrobates sp. Mideopsidae Mideopsis sp° Pionidae Forelia sp. Insecta Ephemeroptera R Heptageniidae Stenonema sp. Trichoptera R continued 37 Table 6-—continued Molannidae Molanna sp. Rhyacophilidae Rhyac0phila sp. Hydropsychidae Hydropsyche sp. Diptera C Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Parachironomus sp. Polypedilum sp. Stictochironomus sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Thienemannimyia_sp. Orthocladiinae Cricotopus sp. MO] 1 USCd Gastropoda R Pulmonata continued 38 “Table 6--continued Lymnaeidae Lymnaea sp. Planorbidae Gyraulus sp. Physidae P_h.x_s_a_ sp. Pelecypoda Heterodonta Sphaeriidae Sphaerium sp. Pisidium sp. 39 Stylaria sp. The oligochaete population at station two and six in- creased significantly (0.005 and 0.001 levels, respectively) in the l973 season. Station five had the greatest combined seasons total abundance (Table 7). The oligochaete seasonal distribution for l972 and l973 at all the Lake Michigan sampling stations is presented in Figure 8. Hirudinea Leeches were found sporadically in samples from Lake Michigan which indicated either they were not abundant in these areas, or the sampling methods were not effectively collecting them. Ostracoda Ostracods from the genus Candona were sampled at the Lake Michigan stations and their population at station six increased sig- nificantly (0.05 level) in 1973 over l972. The ostracods were most abundant at station five in l972 and at station one in 1973 (Table 8). The seasonal distribution of the ostracods at all stations in the two seasons is presented in Figure 9. No ostracods were sampled from station two. Mysidacea At station four, one Mysis oculata relicta (Loven) was collected in August, 1972 and l8 were sampled in October, 1973. Amphipoda Pontoporeia affinis (Lindstrom) was the only amphipod collected from the coastal Lake Michigan sampling stations (Table 9). 4O NNN NNP NP NN NN NN N N NNN NN NPP NN NN NF NPNNNNELNNNNNN NNN NNN NN NN NN NN P N NNN NNF NN NF NN. NN Neaoc NLNNNENN NN NN N N N, N N _ NN N NN N N N .NN xNNNNNN .NP PN N N, N, N N N NP_ N. NN N NN N .NN xNFoumoFNN NNP NN N NN NN N N N NNP NF NN N_ NN N .NN NN_NNNMNENN NN NN NN NF NN N N N N N N N N N NNNNNNELNNNNNN NN NN NN N NP N_ N N N N N N N N NENNN NNNNNNEN N N N N N N N N N N N N N N .NN xNNNNNN N, N, N N N N N N N N N N N N .NN xNFNNNoPNN N_ N_ N F N N N _ N N N N N N .NN NN_NLNMNNNN NNN NN. NN N NN NN NN N NN. NN NN N_ N, NN N_NNN_ELNNNNNN NNN NNF NN N. 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NEE-95¢ t c255 ’ " 0' ,I ”w ’ '51- __-__ .0. . :3on ml ’.Q|fl‘\" “DIN Goo ON $062. 5002 N3 E... .3. «53.. will. 52. 95.. ~82 H00 Emma .094 7.1% is. fl”’ ”’ ON ’ “3"" .0962 E \ 59:5: 302 502 0 8,86 n .363. dooodmkmo 8 u: / uqumu no.“ 3 49 The amphipod, fl. affinis, population at station five and six increased significantly (0.05 and 0.02 levels, respectively) in the 1973 season, being most abundant at station four (Table 9). The seasonal distribu- tion of E. affinis in Lake Michigan for both seasons is shown in Figure l0. Decapoda Four crayfish were collected in a trawl sample taken near station five in August, 1972. Acari Hygrobates sp., Lebertia sp. and Mideopsis sp. were the major water-mites in the Lake Michigan samples with Forelia sp. occasionally present. Hygrobates longipalpis and Lebertia porosa were the most abundant and widely distributed species of aquatic Acari collected in the St. Lawrence Great Lakes comprising 37 percent and l3 percent, respectively, of the sample totals (Modlin and Gannon, 1973). The water-mite population (Table 10) had the greatest combined seasons total abundance at station three. The aquatic Acari population at Stations two, five and six increased significantly (0.0T, 0.005 and 0.00l levels, respectively) in the l973 season. The l972 and l973 water-mite distribution at all Lake Michigan coastal sampling stations 'is presented in Figure ll. l—V‘ 1' choptera Molanna sp., Rhyacophila sp. and Hydropsyche sp. trichopteran jarvae were collected from Lake Michigan in both seasons with a total of only four taken by the anar grab-sampler. 50 0F mp u N m m o o p o o F o o o mNP mm u n N m m_ N om NF NN ON 0 op m wmmm NNNF _mF NNN _mP omm mpn m _Nmp mNF wNm mmm mom NmN N owp wo— n N mm mN n m Nu FF mp Nm NF N m NN mp N P m m P o m n o o o o N mom NNP om N_ N— o Nm 0 NNP Nm FN NN op om F Fmpob pmuoh kabr Nmkm mmmm m\m m\m wpmm Pmuoh wm\op Np\m o~\w mN\o mpxm mcowpmpm Ncommmm commom mNmN commmm NNNN mmcwceou II Axmo mcvpasmm comm co cowpmum comm com Pmpoh NNNsmmimmcchm mcowumpm mcmrnsmm cmm_cowz mcmc Eocw mmpasmm cmcu cmcoa mmmp Ncm Nan 2? .AEoLNNNNNNV mwcwmmm mwmcoaoucoq .muoqmcqs< mo gmcszz .m m~nmh 51 .Axmu m:N_NEmN comm cowamum comm pm cocmu Nm—NENN cmcm cmcoa mmccp No mmmcm>m mcm Nm=_m>v mmm— mcm NNNN com Ncowummm NNNNQEmN :mmwcowz acmm um :o_u:cwcpm_m _mcommmm .Asocpmccwcv NNcNmNm mwocomopcoa .mNNNNcNEN .n ’JfiIIh. .N_ NNNNNN 52 40021224 #00 plan Far... 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N N O mp O N O m N ON O N O O O NF O N N O O .NN N.NNNNN.2 '1 .NN mppcocmc .NN Nmmmcocmxx m .Nm N.Nmomuwz .NN mwocmcmc .NN Nmmmcocmxx N .NN Nwmmomuwz .NN mwpcocmc .Nm Noumcocmxz . .NNN. mcommwm NNN.NENN commmm Nmpop .M\OF NN\O NN\O O\N O\O N_\O mmmp .NNN. NN\N. N.\N N.\N NN\N N.\N NNNNNN NNN. NNN.NN.N ..mpoh N.NEmm-mmch m N. ANN m:..aEmm comm co co.pmmm comm coN No.9.moasouv NNNNNmmm NN..NEmm NNNNco.z Ncmc Eocm No.Nsmm cch cmcoN mum. Ncm Nnm. c. .mmoN mo cocssz mcm mxmh .o. m.cmh 55 OWOSQ' NF ON .. NN (13¢ m— N. kOOO COO r—OO MOO Q'OO 0000 0000 0000 0000 00000 0000 CO .NN m._mcom .Nm NNNNNNNNS .NN mwpcmcmc .NN Nmpmcqmmxm O .NN mN.mcoN .NN NNNmomn.z .NN mwpcmcmc .NN Nmpmcocmxz O .NN NNNNNNN.2 .NN mNpcococ .NN NNNNNNNNNI N 56 .Axmc ac..NEmN comm co.pmpm comm pm cmcmp NN—NENN cmcm cmcoa mwccu No Nmmcm>m Ncm NNN.m>V mnm. Ncm NAN. com NNNNNNNN N:..NENN :mm.co.z Nxmc pm co.uzc.cpm.u .mcommmm .cmoN ... NLNN.N 57 coac.ucoo vl‘ .. oL=NNN 13...... ......NN... ...... .312? 5...... .. I I o I ' I I I I II I I I I I I I I pa N u I I p I N rv vN 81 00.4 .6 5 ON... N N I. Y. N” -.. S—l nhfl I :5 368 n Catoum «£22.62. 503. N 8:05 _m<2 s 3 >551! ms 73...... Z... :3. 181%.“: Now... I I \\ ll’lot\\\\ ; ... v. 8 I E !II 4 E I L I“ v" 31 T as... 1' 1' 8. 8 t T v 8n. 8.; 8 r. .o .o 8... 8: .. L .o N. N. 3.5... .888 395. 5.2 «6:095: 8.: 802 NEtBEsc So: :82 o 3:05 a 5:93 v 5:05 E404 'w/ ”mum noon 59 Chironomidae The dominant chironomid larvae collected from Lake Michigan were from the tribe Chironomini of the subfamily Chironominae. Chironomus sp., Cryptochironomus sp., Polypedilum sp., Parachironomus sp., Glyptotendipes sp., and Stictochironomus sp. were the predominant genera (Table ll). Procladius sp., Conchapelopia sp. and Thieneman- nimyia sp., subfamily Tanypodinae, and Cricotopus sp., subfamily Orthocladiinae, were also collected (Table ll). There were no sig- nificant differences in the chironomid population at any of the six stations for the two seasons. The l972 and l973 seasonal distribution in Lake Michigan is presented in Figure 12. All of the stations had approximately the same size chironomid population. Gastropoda Gyraulus sp., Physa sp. and Lymnaea sp. were collected at the Lake Michigan stations with Gyraulus sp. the most abundant. Station one had the greatest combined seasons total abundance with 633 gastropods (Table 12). No statistical differences were found between the two seasons at any of the six Lake Michigan sampling stations. Six Lymnaea sp. were found in a trawl sample near station five in August, 1972. Seasonal distribution of gastropods for the two seasons at the six stations is shown in Figure 13. Station one in 1972 had the largest gastropod population. Pelecypoda Sphaerium sp. and Pisidium sp. were the two pelecypods sampled from Lake Michigan sampling stations. Station one had the greatest 60 ¢F o F m N m m N o o m o o o N N o o o o o w o o m o o F «N Np n N o o o um NN ON m_ o o N m o o o m o o ¢F op o m o p o o o o o o o o Nm me m ep FF F m noN mm v¢ mp mm c m N_ m N N P w o N o o N o o o m o o F N o o op o o F FF v o pm m N e m_ o F NNF w v_ mp em F N F F o o o o o w e N p o o F oc o o N mm o o em m— NP mp FN ¢N 5 mm_ NN op mN mm m up MNONQQOOV N!— [\NOOOONNOOO I—Q'OOOOCNQ'OOM LOLO MNMQ'Or-fioOOOO I—N NQOFONOOOOO [\03 [\O F NMI—MOLOKDr—Or-N OOONNOOON r-m VOSMCDOLDOOOF-N Nt— OSMF-Q'OOQ'OOOO .qm m: opoUWLo .Qm mwzewccmemcmmsh .am quo_mawmocou .Qm mzwcmpuoNa .am mon_ccmpopthm .gm masocongoopuwpm .gm masocogwnomgmn .nm EspwmmnxPoa P .nm masocogpmuopaxgu .am masocongu N man: .am m: opouwgo .qm mwzswccmsmcmwme .Qm mwaopwawmocoo .nm mzwumFoogm P .am mmqmucmpOpamHm .am masocog_;00p0wum .nm masocogw:uwgma .am E:_wumaa~oa .Qm masococwsoogaxgu P .am masocogwco a VNONOd'F-OOOF- ONONONNONOM Peach rm\op emxm NN\m a\o o\m ¢_\m cowaam mkm_ meowbapm Apmuop mFQEmm-me;p m m_ awn acmpasmm gumm co cowpmpm scam Low cowwwmanouv meowpmam mcwpaEmm :mmwcowz mxmb soc; mmFasmm page Luzon mum? vcm Nmmp cw mmcweocogwcu mo conssz new axe» .__ mpnmp 61 umzcwucou NN N - N N N N N NN N N N N N NNNNN NN NN - N N NN N N N N N N N N .NN N=NNNNNNNN N N - N N N N N N N N N N N .NN NNNENNNNENNNNNN NN N - N N N N N N N N N N N .NN NNNNNNNNNNNNN NN NN - N NN N N N NN N N N N N .NN NNNNNNNNNN NNN NN - NN NN NN NN N NN NN NN N N NN .NN NNNNNNNNNNNNNN NN N - N N N N N NN N N NN N N .NN NNENNNNNNNNNNN N N - N N N N N N N N N N N .NN ENNNNNNNNNN NNN NN - NN NN NN NN NN NNN NN N NN NN NN .NN NNENNNNNNNNNNNNN NNN NN - NN N NN NN N NNN NN NN NN NN NN .NN NNENNNNNNN N N N N N N N N N N N N N N N NNNNN NN N N N N N N N N N N N N N .NN NmmoNNNNNN N N N N N N N N N N N N N N .NN NNNENNNNENNNNNN N N N N N N N N N N N N N N .NN NNNNNNNNNNNNN NN NN N N N N N N N N N N N N .NN NNNNNNNNNN NN NN N N N N N N NN N N N N NN .NN NNNNNNNNNNNNNN NN N N N N N N N N N N N N N .NN NNENNNNNNNNNNN N N N N N N N N N N N N N N .NN ENNNNNNNNNN NN NN N N N NN N N NN N NN NN N N .NN NNENNNNNNNNNNNNN NN NN N N N N N NN NN N N N N NN .NN NNENNNNNNN N NN NN N N N N N N NN N N N N N NNNNN N N N N N N N N N N N N N N .NN NNNNNNNNNN N N N N N N N N N N N N N N .NN NNNENNNNENNNNNN NN N N N N N N N N N N N N N .NN NNNNNNNNNNNNN NN NN NN N N N N N NN N N NN N N .NN NNNNNNNNNN NNN NN N N NN NN N N NN N N NN N N .NN NNNNNNNNNNNNNN NN NN NN N N NN N N N N N N N N .NN NNENNNNNNNNNNN N N N N N N N N N N N N N N .NN ENNNNNNNNNN NNN NNN NN NN N NN N NN NN NN N NN N N .NN NNENNNNNNNNNNNNN NNN NN NN N NN NN N N NNN NN NN NNN NN NN .NN NNENNNNNNN N 62 NN NN - N N N N N N N N N N N NNNNN N N - N N N N N N N N N N N .NN NNNNNNNNNN N N - N N N N N N N N N N N .NN NNNENNNNENNNNNN N N - N N N N N N N N N N N .NN NNNNNNNNNNNNN NN NN - N N NN N N NN N N N N N .NN NNNNNNNNNN NNN NN - N NN NN N N NN N N NN N N .NN NNNNNNNNNNNNNN NN NN - N N NN N N N N N N N N .NN NNENNNNNNUNNNNNN NN NN - N NN N N N NN N N N N N .NN NNENNNNNNNNNNN N N - N N N N N N N N N N N .NN ENNNNNNNNNN NNN NN - NN NN NN NN N NN NN N N NN NN .NN NzeocoLNNNNNNNNN NNN NNN - NN NN N N N NN NN NN N N N .NN masocoNNNN N NNNNN NNNNN NNNNN NNNN NNNN NNN NNN NNNN NNNNN NNNNN NNNN NNNN NNNN NNNN NNNNNNNN NNNNNNN NNNNNN NNNN NNNNNm NNNN @358 ll umacwuzou--NN mNnmN 63 .NNNU mNNNNEmN comm :oNNNpN :umm um cmxmp NmNNENN NNNm NNcoN mmgcu No mmmgm>m NNN NmNNN>v mNmN NNN NNmN NNN NNONNNNN mchNENN cmmNguNz NNN; pm coNNNNNNNNNu NNNNNNNN mauweocogwgu .NN 8%: 64 ua==_u:ou H00 Hum» 63‘ we Tm.» _m _ >42. u: ><2 .Lh b h b. 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E v :0:on 66 N N - N N N N N N N N N N N .NN NNNMN N N - N N N N N N N N N N N .NN NNNNNN N N N .N - N N N N N N N N N N N .NN NNNNNNN N N - N N N N N N N N N N N .Nm Nm MN NN N - N N N N N N N N N N N .NN NNNNNN N N NN N N N N N N N NN N N N N N .NN NNNMN NN NN N N NN N N N NN N NN N NN NN .NN NNNNNN N N N N N N N N N N N N N N N N .NN NNNMN NN NN N N N NN N N NN NN N N N N .NN NNNNNN N N N N N N N N N N N N N N N N .NN NNNMN N N N N N N N N N N N N N N .NN NNNNNN N N NNN NN NN NN N N N N NN N N NN NN N .NN NNNNN NNN NNN NNN NN NN N N NN NNN NN NN NN NN NN .NN NNNNNNNN N NNNNN NNNNNTNNNNN NNNN NNNN NNN NNN NNNN NNNNN NNNNN NNNN NNNN NNNN NNNN NNNNNNNN mc0mmmm Cowmmm mmm— commmm Nump NNNNNENN NNNNNN mNNENmummNNN N NN NNN chNNENm scum :o :oNNNpm comm Now NNNNNNoNEouv Ncowgmpm NNNNNENm cmmwgowz NNN; EoNN NwNNENm NNNN Nazca mNmN new NNNN :N Nvoaogummm mo gmaeaz ucm Nxmp .NN NNNNN 67 .Axmu mchNENN comm NONNNNN comm pm :mxmu NmNNsNN NNNm Loco; mmggp No mmNNm>N NNN NmzNN>v NNN— ucm NNmN Now Ncowumpm mchNENN cmmwguwz mxmq pm cowuzawLuNNu choNNmN NNoNNNNNNw .h! . [es-A.“ .NN NNNNNN coacwucou Nu: iNflua N mp usaapm >155 3.x. >¢3 I... . .. .o ‘9 .8 NE --- nso. II was .00 LE. 1 .363. so: In“. 8... r a 81 8% +9 g; ran 8... §1 . on 9'. 8... RU ._ 8.. v8 80.1 80. 12. gl §J 1 0801 3. «5:95:80: 802 «5.3.5: 5.! n .3..on .8 u .8:on dooaomkm<0 . cote-m 2 .38 am/ummm uoou 69 N.» 78 woo ham» 63¢ 8 8 u. I a. use ..ll Eh. I >4... 02?. >48 oh an ......N a 8.4 0024 §~L NE :85... 502 19 Ta .2. 368 802 o :0:on m— champm Woo him» “a“ >5... U3... ‘ llo‘ \\\\ 831 12. 80".. Nona-.... 513:5: 502 802 N n cote-m (accomhmdo V cote-m 1 3m/nqmlm noon 70 combined seasons total abundance of 557 pelecypods (Table l3). The pelecypod population at station one decreased significantly (0.025 level) in the l973 season. Sphaerium sp. was in greatest abundance at all the stations. The seasonal distribution of pelecypods in the 1972 and 1973 seasons is presented in Figure l4. Stations one and four had the greatest populations with rapid and variable changes in their abundances. Percentage Composition of Benthic Macroinvertebrate Populations The percentage composition of the benthic macroinvertebrate groups in the population at each station for two-month periods, May— June, July-August, and September-October, was determined, and the popu- lation group percentages of the two seasons were paired. Comparisons of these pairs of the same two-month sampling period at the same station were completed statistically and graphically. Spearman rank correlation coefficients (Siegel, l956) were calcu— lated for the paired percentages of the benthic organism groups (Table l4). The rS (Spearman rank correlation coefficient) is a measure of the association between two variables whose individuals or observations are ranked in two-ordered series. The differences between the two-ordered series of variables is an indication of the diSparity between these two rankings. If there is an association between the two rankings, in this case the two-percentage compositions, the disparity is not great enough to be judged statistically significant. The rS equation for ties in the ranks and the critical rS value table in Siegel (1956) were used due to the many ties in the paired ranks and the low number of ranks (n<:lO). 7l m m - o m o o o o o o o o o .am E=Pupmpa m N - F e o N o N o o o N 0. .am e=_emmgmm m NN m - N o o P o m_ _ _ o m N .Qm 2:, _m. em mN - m_ e o m o mN _ N m OF N .am Esteem: m m an o o o o o o o mm o _F o _F _e .am 5:. ,mFa NNN om NN m N m mm o NNN N _N a, me No .am Esteem; m e N_ mp o e o m o o e _ o N _ o .am 2:, Fm.a mm em m mp m_ m_ o o «m o_ m o o N .am Esteem; m m _ _ o o o _ o o o o o o o o .am Ezpusm.a o_ m o o o o o o e o o o o e .am sngmmgmm N 0N, me mN m m m m o NN e __ mN m. oN .am 5:, Pm. _me NON om, NN m_ m NF w NNN NN NN _m mN em .am Engmm; m P Patch Patch FN\o_ eN\m NN\N m\N ©\o ¢P\m _mpoc om\o_ N_\m op\m NN\© m_\m mcowpmom mcommmm commmm commmm .lwmcwneo Apmpoh mpasmm-mmcch w m? xma mcwpgsmm zoom co :owpmum scam com cowawmoasouv mcompmum mcwpasmm :mmwcuwz mxmb soc» mmFgEmm nmgw cocoa mum” was Nump cw muoaxumpma mo consaz new axe» .m_ m_amh 72 .Azmu mcwpasmm some cowpmpm sumo pm :mxmp mmFQEmm nmgm meoa mmczp do wmmgm>m wgm mmzpm>v mumF new mNm_ com mcowpmpm mcwpaEmm cmmwguvz mxmb pm cowuznwgpmwu Pacemmmm muoazuwpma .e_ mczmwu 73 _ulllus vascpucou Poo “Emu 63¢ >41. in. >¢I _u m _m_FF, new ”_N» , e— «Lamp; 18......43933 us. mu. 3g?“ gi n52! g; NEE-9.3.50: n gaze—m igfi «5.8.5.. 5.: N 8:03 om4wm _ cot—zm 3W] JOQWI'IN noon 74 ...»... ............ ._N....... _ Ntuio- ”Kenn: bid. *1. >48 .8 «513.5: 5.! 0 3:05 g; «p agamvm Hoofig Tau—Imh as; ml: 2:. m3. 2...... 88> 8 do. 131.3%? Sag: a... .... 8.. \ ......Y .9 g; 81.8 ..8 g1 81 6n g- .09»! «Exzsgc‘ so! 0 Steam c totem 'uuuqmm noon 75 o_. N m m UmH0woomm< uoz Papop m e m P vmumwuomm< pouch 0 H Z w H c m " ..— N P NN mm. mN mm. PN om. o x x x N N C m u c N u c m o NN on. mN em. FN wm. m x x x N H e. m H C m H E o m 0N mm. mp NN. mp om. v x x x N H c m H C m H C N P ON mu. mp om. NF ON. m x x x 0 ...... E 0 H c m H C N F N_ mm. mp on. m_ Nm. N x x x m H C m H Z w H C F N NP em. mp mm. m_ Fm. F x x x cmum uwpm Lmnasz umym uwpm Lmasaz umam umum gmnszz umpm noun mcowpmgm -Puomm< -wuomm< mgzmwm -wuomm< -wuomm< mesmwm swuomm< -woomm< mgamwg -wuomm< swoomm< uoz uoz uoz poz _Npoh Lwnopuo-gmnempnum umnms:wogumz umspcmm cmmmsumz mxmg we comwgmanu Low mpcmmowmmmou cowpmpmgcou scum coagmmqm mnmp new Nnmp comzpmm covwmpsaom mo cowpmmoasoo ommpcmucma .maaogo mumgn .v_ mNQNH 76 In testing the association for significance using rs, the null hypothesis (H0) is that the twomranked series of percentages are un- related or not associated in the population; the 1972 and 1973 population percentage composition at each station is not related or associated. If calculated rS < tabulated critical value of rS (0.05 significance level), then retain Hp; if calculated rS 3_tabulated critical value of rS (0.05 significance level), then reject H0 and accept H1 which states that the two-ranked series of percentages are related or associated. Station one benthic macroinvertebrate population comparison for the May-June sampling period (Figure 15) was not associated; the appearance and development of organisms in the spring at different times is probably responsible for this difference. The July-August (Figure 16) and September-October (Figure 17) sampling periods had rS values greater than the critical value indicating that these two com- parisons had populations which were associated or related. The May-June (Figure 15) and July-August (Figure 16) population composition comparisons at station two were not associated which was primarily due to the greater diversity of groups in the 1973 season. September-October comparison (Figure 17) indicated that the two season population percentages were associated. Station three May-June (Figure 18) and July-August (Figure 19) comparisons were not associated or related. This lack of association between the populations is probably caused by the greater number of organisms/m2 and the predominance of oligochates in May-June 1972, and the fewer samples in July-August 1972. The September-October comparison (Figure 20) had populations which were associated. Figure 15. 77 Comparison of May-June benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations one and two. 78 MAY- JUNE oooooooooooooooo OOOOOOOOOOOOOOO .22 0/o I . 330/0 Station | (6 samples) 29 1973 m |4|7.5/ ER] Pelecypoda E Ostracoda la Acari )3 Amphipoda Annelldazmlgochoeta ID Dlpiora: Chironomidae Station 2 (6 samples) Annelldo: Hirudinea Figure 15 1%: Gastropoda 'Avorogo Total Numb» of Cranium Figure 16. 79 Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations one and two. 80 JULY-AUGUST Station I (3 samples) (no July samples) 2904.3/m2' Station 2 (3 samples) 3.03% (no July samples) ....... : .. OOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO 0000000000000000000000000000000000000000000 OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOO OOOOOOOOOOOOOO OOOOOOOOOOOOOOO 0000000000000000 OOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO .................................................... ................................................... ................................................... OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOO 000000000000000 CCCCC I972 4:5.e/m2' D Amphipoda Annellda: Ollgochaeta Diptera: Chironomidae Gastropoda Figure 16 I973 929.2 m” m Pelecypoda Q Ostracoda Acari Annelida: Hirudinea 'Average Total Nunber of Otoantem 81 Figure 17. Comparison of September-October benthic macroinverte- brate populations of 1972 and 1973 Ponar grab samples from stations one and two. 82 SEPTEMBER -OCTOBER 1 2939.0 /m2 & Ostracoda Acct Amellda: leudinoa 97 2 t 532.4 /m2 Dlptera: Chironomidae Annelida: Oligochaeta D Amphipoda Station 2 Trlchoptera t Gastropoda Average Total Number of Organleme Figure 17 Pelecypoda 83 Figure 18. Comparison of May-June benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations three and four. 84 smflm . MAY-JUNE (6 samples) 250% .92°/ l972 I367.|/m2 Station 4 (6 samples) eeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee llllllllllllllllllllllll eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee ............. OOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOOO llllllllllllllllllll IIIIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIII oooooooooooooooooo IIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOO IIIIIIIIIIIIIIII OOOOOOOOOOOOOOO IIIIIIIIIIIIII 0000000000000 IIIIIIIIIIIII IIIIIIIIIIII ........... 0000000000 ......... ........ ooooooo I972 , I973 c 4338.0 /m" 2964.2 lm2 Amph'mdo @ Ostracoda Annellda: Oligochaeta Acari 0'9“”: Chlronomldae & Annellda: leudlnea Gastropoda I (grouping of less than 2%) "“ mam 1. °' 'Amugo Total Numbet ot Organism 85 Figure 19. Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations three and four. 86 JULY-AUGUST Station 3 (3samples) (no July samples) ..... ........ OOOOOOOOOOOO IIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOO eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ........................................ OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ..................................... OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO 1972 2. I973 2. 2772.0/m 2570.4/m Station 4 (3 samples) . . (6 samples) 2.4 .494, ("0 NY 30mph” ' 424 . i'.‘ .h: ‘11:: "igi'i E) 'g o. ...... uses/m2 2230.2/m2 D Amphipoda a Ostracoda Annelida: Oligochaeta I; Acari Dlptera: Chlronomldae Annellda: Hirudinea GOWOPOGO I (arouplng of less than 2%) Pelecypoda Figure 19 ‘ Gastropoda and Acari Average Total Number at Organisms . “mum. Figure 20. 87 Comparison of September-October benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations three and four. 88 SEPTEMBER-OCTOBER Station 3 (6 samples) I972 I973 22 522 ”“2, 1238.0 lmz' Station 4 46ll.6/m E] Amphipoda Pelecypoda Annellda: Oligochaeta E Ostracoda Diptera: Chlronomidae Acorl GO’IVOPOCIO 'Amm Total Number ot Oroaleme Figure 20 89 Station four population comparisons (Figures 18, 19, and 20) indicated each paired population was associated. There is less varia- tion in the abundance and distribution of the benthic groups at this deep water station. Station five population comparisons (Figures 21, 22, and 23) were all unrelated indicating the Lake Michigan area immediately adjacent to the plant is most variable. The May—June (Figure 21) and September-October (Figure 22) com- parisons at station six were not associated due to greater group diversity and number of organisms/m2 in 1973. The July-August (Figure 23) comparison indicated that the two populations were associated. The Spearman rank correlation coefficient is only an indication 0f whether two populations are “similar or different" due to the dis- Par‘ity between their paired series of organism groups. It should be Viewed as an indicator in making conclusions on the relationship be- tWeen the populations. The number of ties resulting from the absence 01: groups from pairs and the small number of samples may have adjusted the rS values, indicating a greater disparity than actually exists. The important trends in these comparisons are that the shallower Stations have populations which are more variable, and the May—June and July-August sampling periods show greater variation. Figure 21. 90 Comparison of May-June benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations five and six. 91 MAY—JUNE Station 5 I.” °/o 2.3970 I972 2t I973 29 1332.4 /m l978.2/m Station 6 20/ (6 samples) 2.44% "2” ° ........... IIIIIIIIIIII IIIIIIIIIIII OOOOOOOOOOOOOO OOOOOOOOOOOOOO IIIIIIIIIIIIIII 000000000000000 IIIIIIIIIIIIIIII OOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIII OOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOO IIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIII I972 2, I973 2, 258.3/m 333.9/m D Amphipoda Pelecypoda Annelldazmlqochaeta Q Ostracoda Dlptera: Chlronomldae Acari .5: 303'“,me 'Avorogo Total Number of thcnltmt Figure 21 92 Figure 22. Comparison of September-October benthic macroinverte- brate populations of 1972 and 1973 Ponar grab samples from stations five and six. 93 SEPTEMBER - OCTOBER Station 5 (6 samples) . ' _ (3sompl08l 279% l.49°/o eeeeeee eeeeeeee ......... IIIIIIIII eeeeeeeeeee eeeeeeeeeee eeeeeeeeeeee eeeeeeeeeeeee eeeeeeeeeeeee eeeeeeeeeeeeee eeeeeeeeeeeeeee eeeeeeeeeeeeeee OOOOOOOOOOOOOOO eeeeeeeeeeeeeeee eeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeee IIIIIIIIIIIIIIIIIIIII eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeee nnnnnnnn ............... eeeeeeeeeeeeee eeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee nnnnnnnnnnnnnnnn l972 . 2646.0/m2 29937477/m2' Station 6 (6 samples) 0 .. (“mm“) "29 “396% I972 , '973 295' ’"12 l467.9/m2. E] Amphipoda Pelecypoda Annelida: Oligochaeta Acari Dlptera: Chlronomldae I (Fouling of less than 2%) Pelecypoda, Ostracoda, Gastropoda and AW" Figure 22 ' Average Total Number of Organism! 4‘3: Figure 23. 94 Comparison of July-August benthic macroinvertebrate populations of 1972 and 1973 Ponar grab samples from stations five and six. JULY- AUGUST (6 somples)m 1' - Station 5 (3 samples) (no July sanples) I972 3ll8.5/m2' 1842.8 lmz' Station 6 (3 SONGS) . 5%: (n0 July samples) ..-.-.. -.-.. ..... 0000000 ....... ........ ......... IIIIIIIIII OOOOOOOOOOO ........... 000000000000 OOOOOOOOOOOO OOOOOOOOOOOOO 000000000000 IIIIIIIIIIIII OOOOOOOOOOOOO .............. ooooooooooooooo IIIIIIIIIIIIIII OOOOOOOOOOOOOOO IIIIIIIIIIIIIII I972 2. I973 2' 403.2/m l808.l/m D Amphipoda @ Ostracoda Annelida: Oligochaeta / Acari Dlptera: Chlronomldae - (grouping of less than 2%) Pelecypoda and A.leudlnea Gastropoda a (grouping of less than l’lo) Figure 23 A.leudlnea and Trlchoptera POIecypmo 'Averoge Total Newer ot Orgaeteme 96 Dispersion Index of Major Benthic Macroinvertebrate Groups The variance to mean ratio is used as a comparative index of dispersion. Green's coefficient, (S:<§2; 1 (Green, 1966), which is independent of variation in sample size, mean, and sum of observations, was used to calculate the values for the seven major benthic groups at each of the six stations for both seasons (Table 15). This index is suitable for comparisons of contagious distribution, and ranges from zero for random dispersion to one for maximum contagion (Elliott, 1971). These values from the dispersion index should be considered as indicators of the variance to mean ratio, rather than a precise measure- ment because of the small and unequal sample sizes. Lake Michigan Artificial Substrate Samples Multiple Plate Samples The multiple plate samples taken from each Lake Michigan sampling station after two months collected predominantly chironomids (Table 16), mainly from the tribe Chironomini of the subfamily Chironominae. and water-mites. These plate samplers primarily collected benthic macro— invertebrates which are gn_the bottom: isopods, amphipods, water-mites, chironomids and gastropods. Asellus sp. isopods were sampled in greater abundance on the multiple plate samplers than in the Ponar grab samples. Ten ephemeropteran nymphs, Stenonema sp., were sampled on the multiple plate samplers while none were collected in the Ponar grab samples. 97 E m_ u : ”NF u :+ ”NP u c m— u c ”mem mFQENm I .1 em. 00. oo. oo. oo. Po. no. 00. no. oo. me. 00. No. mo. 0 e. e. .4. .1 a. a. e. a ... .1 e a a. a oN. mp. ow. mF. mo. NO. NO. oF. mo. mo. mm. Nm. _o. mo. m a. e. e. h .1 e. e e a. .1 e. e e .« ION. m_. -No. mN. -eo. N0. .N9. NP. -mo. Po. two. 00. .00. «o. a e e. .<. e. e. e. e. +op. 3.oo. +mN. 3N0. +eo. ewe. +mo. «FF. +mN. emo. +wm. eeN. +mo. «mo. m *Nm. *mN. «Fm. «co. Nee. smo. Nee. eoo. Noe. NNN. N00. «00. Nee. emo. N «_P. *No. *¢_. e_o. NNN. soc. *No. smo. NB. 3N0. NFN. «KN. NNo. eNm. _ mNm_ NNmP mnmp NNmF mmmp NNmF mNmP NNmF mNmF NNmF mNmF NNmF mNmF NNmF mcowpmum avomxumFma muoaocpmmo mmquOCOLNLU Pgmu< anomwgme< muoumgpmo mummcoommPo mmFaENm coca cocoa mum? ucm NNmF :mmwguwz NNMN EoLN Nxmh mpmgnmpem>cvogumz uwgpcmm Lowe: Low xmncH cowmgmamwo mp mFQMH 98 Table 16. Taxa and Relative Abundance of Lake Michigan Benthic Macro- invertebrates in 1972 and 1973 Multiple Plate Samples (6 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0—25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-100% Nematoda R Annelida R Oligochaeta Plesiopora Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Arthropoda Eucrustacea Malacostraca Isopoda R Asellidae m sp- Amphipoda R Haustoriidae Pontoporeia affinis (Lindstrom) Decapoda R continued _I"" ...-... 99 Table 16 -c0ntinued Arachnoidea Acari C Lebertiidae Lebertia sp. Hygrobatidae Hygrobates sp. Mideopsidae Mideopsis sp. Insecta Ephemeroptera R Heptageniidae Stenonema sp. Trichoptera R Rhyacophilidae Rhyacophila sp. Hydropsychidae flydropsyche sp. Diptera C Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Polypedilum sp. Glyptotendipes sp. ' continued w 100 Table l6--continued Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Planorbidae Gyraulus sp. Physidae Physa sp. 101 Five trichopteran larvae, Rhyacophila sp. and Hydropsyche sp., were collected on these multiple plate samplers in Lake Michigan. Physa sp. gastropods appeared to be selectively collected by the multiple plate samplers. The multiple plate samplers collected benthic organisms which presented a different composition compared to the Ponar grab samples. However, weather conditions and vandalism made it difficult to keep many plate samplers in Lake Michigan for any length of time. Rock Basket Samples The rock basket samples from the protective rock jetties and breakwall area indicated that this area had attracted benthic macro- invertebrates by providing many new habitats (Table l7). Gammarus fasciatus and g3 pseudolimnaeus amphipods, which dominated these samples, were found in Lake Michigan only on the rock baskets. These amphipods move about on the surface of rocks and plants (Bousfield, 1974), and the rock jetties and breakwall provide this habitat. Trichopteran larvae, Rhyacgphila sp. and Hydropsyche sp., were found abundantly in the rock basket samples. These trichopteran larvae are net-spinners found usually in a lotic habitat (Denning, 1971). The great amounts of water passing between the jetties constitute a lotic environment to which the benthic organisms are responding. Trichopteran larvae were sampled in greatest abundance in this entire study on the jetties and breakwall. Waterimites, chironomids, gastropods, oligochaetes, leeches, and isopods were also collected from the rock baskets. 102 Table 17. Taxa and Relative Abundance of Lake Michigan Benthic Macro- invertebrates in 1972 and 1973 Rock Basket Samples (2 Samples) A‘... Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-100% Annelida Oligochaeta R Plesiopora Tubificidae Limnodrilus sp. Tubifex sp. Hirudinea R Arthropoda Eucrustacea Malacostraca Isopoda R Asellidae Asellus sp. Amphipoda C Gammaridae Gammarus fasciatus Say 9: pseudolimnaeus Bousfield Arachnoidea Acari R continued 103 Table l7--continued Hygrobatidae Hygrobates sp. Insecta Trichoptera Hydropsychidae Hydropsyche sp. Diptera Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Polypedilum sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Physidae Physa sp. DISCUSSION OF LAKE MICHIGAN STUDY Statistical Analyses of Lake Michigan Benthic Macroinvertebrates The Lake Michigan coastal area study compared the 1972 and 1973 " ”v‘ e.— - - benthic macroinvertebrates at each sampling station. A comparison between the two seasons was difficult because of the great variability in the benthic macroinvertebrate populations. Many statistical analyses of benthic macroinvertebrate populations have been done to determine patterns and changes, ranging from basic statistical tests to diversity indices and multivariate data analyses. Wilhm (1967) compared diversity indices and their application to macro- invertebrates in streams for detecting pollution. Multivariate analysis was used to identify functional components of the benthos in a Nova Scotian bay (Hughes, Peer and Mann, 1972). Statistical testing should determine differences and trends in data which can be interpreted biologically. Single classification analysis of variance, approximate t-test, Spearman rank correlation co- efficients, and a dispersion index were used in the evaluation of the Lake Michigan benthic macroinvertebrate populations. 104 105 Negative Binomial Distribution of Benthic Macroinvertebrate.Population The spatial distribution of the bottom fauna is very important in estimating the total population. Benthic macroinvertebrates general— ly group or clump together on the bottom. Because they are not randomly distributed, most statistical tests cannot be directly applied to the data. The negative binomial distribution has often been considered the appropriate model for macroinvertebrate populations (Anscombe, 1949; Bliss and Fisher, 1953; Debauche, 1962; Elliott, 1971). The parameters of this distribution are the arithmetic mean u and exponent k. The k statistic is related to the spatial distribution of the benthic macro- invertebrates with l/k a measure of the excessive variance or clumping of the bottom organisms. "N The calculation of k is: k = 2 s -3? Because k is small in extremely clumped populations and the mean is usually small due to zero counts, the benthic organism counts must be transformed to normalize the frequency distribution, eliminate the dependence of the variance on the mean, and guarantee that components of the analysis of variance are additive (Elliott, 1971). The appropriate transformation of the benthic macroinvertebrate counts is determined by the calculation of the k statistic which is dependent on the original frequency distribution of the counts. an.-‘..L1-n.'. ‘. ‘7'.- ‘ew- _— 106 Transformation of Original Data The k factor for the combined two seasons was calculated for the oligochaetes, ostracods, amphipods, water—mites, chironomids, gastropods, and pelecypods (Table 18). The k values for these seven groups were all less than 1.0 and the variances were all greater than the means. The log Cx-+ l) transformation was chosen (Elliott, 1971), and per- formed on all the individual counts from the seven groups. Homogeneity of Variances One assumption of the analysis of variance is that the samples come from populations which have the same or equal variances. The variances of the seven major benthic macroinvertebrate group comparisons for each two-month sampling period at each Lake Michigan station were tested to determine whether they were significantly different, using the F-test in Sokal and Rohlf (1969) and Elliott (1971). F = variance] (largest variance always in the numerator) variance2 v1 = nl ' 1 df v2 = n2 ' 1 df Single Classification Analysis of Variance A single classification was performed on the comparisons whose groups had homogeneous variances. This analysis of variance for two groups is the same as the t-test of the differences between two means which is the traditional method of determining a difference (Sokal and Rohlf, 1969); they feel that there is no advantage to the t-test in terms of ease of computation or understanding. In the single 107 Table 18. Mean (7), Variance ($2), and Excessive Variance or "Clumping" (k) of Lake Michigan Benthic Macroinvertebrate Major Taxa from the Combined Six Stations and Two Seasons (Ponar Grab Samples) Benthic Macroinverte- brate Groups 2 (192 Samples) >gmmmm .sN 3.3323 LUDINGTON PUMPED-STORAGE RESERVOIR LAKE MICHIGAN \ \ \ \ ,\?\\\ 31x ’ ’//)'@ at IIIIIIQ 120 \\\~\ \\\\\\\ III II // /////IIIII///I/IeI IIIIII \\\ VIII/fly, III; I / \4 Q \\ \\\ \ \ I / / ‘ J ...—A \- \{SE: I§ @\\\\\ Figure 24 121 a Perkin-Elmer 240 Elemental Analyzer by the Water Research Analytical Laboratory of Michigan State University. Reservoir Physical and Chemical Studies Weekly Pumpjpngates The reservoir water exchange rates and pumping schedule (Figure 25) shows the approximate time when each of the pumping units, Francis type pump-turbines, was Imxt into operation indicated by the numbers 1-6 in the figure. Maximum pumping activity occurred when units 1-5 were operational. The shaded areas of the graph reveal that most of the pumping occurred between 7:00 P.M. and 7:00 A.M. with only 15 percent of weekly volume accomplished during the daylight hours (unshaded areas of graph), which were usually on Sundays (Figure 25). Pumping rates of 200,000 acre-feet or more per week were common from August through December, 1973. Water Temperature Results Surface and bottom water temperatures are averages from multiple measurements taken each of the 77 different sampling days (Figure 26). Reservoir temperatures ranged from 3 C in April to 24 C in September, 1973, reflecting the thermal conditions in the adjacent Lake Michigan coastal areas. Water TransparencyResults Secchi disc values from the reservoir and Lake Michigan stations three and five (Figure 27) are averages of multiple measurements taken . each sampling day. Reservoir transparencies ranged from 0.6 m in April 122 .ApTc: mcwngzuuaE:a some to open _Ncowpmcoao “move ms“ wumowucw oIF maNpEscv mNm_ cw x033 some LON Epo>gmmmm mmaaoom woman; cogmcwczo one No zpwrwpmamo caressa we:_o> Loom: Winch. .mN 3.33,; mesh 3‘ ‘ I“ 123-. N 23: mum. owo >02 ...00 rmmm 0:4 .5... 22. >52 «Ed. 5:2 mm... 24... . 2 02.0 2 .... com. .e G ... 8m. 2.... 8.5.0 IO N 0 ID IO N 00. mm. On. 0». 8 . N 901 x 1333 auov‘aadwnd awnion mNN 124 .mNm_ acres; mco_peum mcwpaEmm L_o>gmmwg om mmgsuecmaemu Lopez Eouwon vcm momwgzm mmmem>< .eN 32:m_u 125 oN ossupm .3525: .3200 39.535 .2694 :2. 2.2. so! _ :23 [FEEIELIELFE-E. DD—D tr bh Db bP b R0 .3 I.‘ +0. 0e _\s a \ . .. . s» \ .n. a x... I ,\\ ; . ‘ - K . . \ N .. T\ N , III 2058 .8 I uHaSm n8. .mumaficuazm» 5.23 20>..me 126 .mump mcwgzu mcowpmum mchQEmm L?o>gmmmg gm ucm .m>ww use mmggu m:o_pmpm mc_FaEmm cmmwgumz mxmA um mmcwnmmg umwv wcoumm mmmgm>< .n 4.14.3.1. dim? I ‘4: w .- ONN mgzmwm 127 mm «gnaw; cum2w>oz munchoo mumekmmm ...mzoad >42. uzas >42 42:: .F_ r :_ I _ _ ___ _E E. ___: : Z. = ___ = ___ _ == ___. == _ _=_ LLF C. t b I _? p .‘ .. .N W O .n u 3 n5. £383.. of 353.2 8:. 285 _ ___E _ : _EFE :— :: hb ___ — :F: P. ... 10.. n 8.66 ..... \x 10d I 0 VI w . s I 2.. 1 ‘01 ..IIII .I\ I cl \\ x 0! x a ncotgw \ ~ . I \ IO.” .0 \ o \\ \s .. I'll \ ‘ N * \\ ‘0 x O.— \\ u \ s \\ pa“ lO.‘ . s c h. . 10.0 2.2 63222 3.3 32.33 on... 23.5 128 to 4.l in July, l973. Lake Michigan stations three and five transparv encies ranged from 0.6 in April to 5.6 in July, l973. The reservoir transparency was consistently lower than the adjacent Lake Michigan areas. Water Turbidity Results Turbidity measurements were made in formazin turbidity units, ranging from 0.4 to 12.0 (Table 19). In general, the reservoir turbid— ities were similar to the adjacent Lake Michigan sampling areas (Figure 28) with the highest reservoir values in April, 1973. Water Chemistry Results The chemical parameters were within the following ranges through- out the reservoir: pH 8.2-8.5; dissolved 02 9-l2 ppm; alkalinity 102-122 ppm; dissolved solids l59-190 ppm (Liston, l974). The physical and chemical conditions of the reservoir were within the same ranges as those from the adjacent Lake Michigan areas. The benthic macroinvertebrates were affected by the same water quality con- ditions in the reservoir as in the adjacent Lake Michigan areas. Sediment Chemistry Results Percentages of total carbon, hydrogen, and nitrogen on a dry weight basis were determined on reservoir sediments taken by the Ponar grab-sampler. The ranges of the percentages of these elements in the sediments were: carbon l.l2-5.43; hydrogen 0.07-0.31; nitrogen 0.02- 0.l3. No significant trends or patterns were detected in the chemical content of these sediment samples. These analyses are generally 129 Table l9. Surface Turbidity Measurement (Formazin Turbidity Units) Descriptive Statistics from Reservoir Sampling Stations During l973 Station 1 4 6 Number of readings 55 46 54 Range 0.5-ll.5 O.5-ll.0 0.4-ll.5 Mean 2.79 3.00 3.20 Variance 2.42 4.02 4.84 Standard deviation l.56 2.01 2.20 Coefficient of variation 55.8% 67.0% 68.8% 130 .mkmfi mcwcsu mcowpmpm mcwpaswm L_o>gmmmc pm vcm .m>wm new omega m:o_pmpm mchaEmm :mmwgowz mxmA um mucwsmczmmms xpwcwncsp wumecsm mmmcm>< .mm mesmwu l3] mm ogamwu cunxu>oz «moohoo «unsupamm pmaoaa >423 —:_ F :— pr _ ___ _— :— —P = =— 2 hr = :— — 2: mzn... re : p:: 2.— >4! l—Lb 1:th — F—LL _ : __z — E. h F: :— nsm. 52:30: £29.: 82.3 e r__ IJLL 11111 mun mpgqml ugzouuog O O. 6.: Dd. o 8:06 .--: n 8.35 I 2.2 .5255 3.3 »._u_n.:. 325m 1 1 111] l [111 l 6. ON 6» Of 0,» on Os. 66 00 OO. 0.: ON. On. suun mmqmi momma 132 accurate to 0.05 percent, however, obtaining a homogeneous subsample was the major difficulty with an average 0.07 difference between dupli- cate subsample percentages. Reservoir Ponar Grab Samples The oligochaetes and chironomids dominated the 42 Ponar grab samples taken from the reservoir on May ll, June 19, July 18, August 30, and October 10 during 1973 (Table 20). TOTigochaeta Oligochaetes showed a rapid increase and sustained high level in the Ponar grab samples in the first season of reservoir operation (Figure 29). Limnodrilus sp., Peloscolex sp. and Tubifex sp. were the genera of Tubificidae found in the reservoir (Table 2l); these three genera also were found in the Lake Michigan samples. Many immature and unidentifiable oligochaetes were present in these samples (Table 21). Hirudinea Two leeches were sampled in June, l973 from the north end of the reservoir. Amphipoda Amphipods colonized the reservoir and increased throughout the entire season (Figure 30). Gammarus fasciatus was eight times more abundant than g, pseudolimnaeus until August, l973. Pontoporeia affinis was first sampled from the reservoir in August and increased through the end of the season (Table 22). 133 Table 20. Taxa and Relative Abundance of Reservoir Benthic Macroinverte- brates in l973 Ponar Grab Samples (42 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-100% Annelida Oligochaeta C Plesiopora Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Hirudinea R Arthropoda Eucrustacea Malacostraca Amphipoda R Haustoriidae Pontoporeia affinis (Lindstrom) Gammaridae Gammarus fasciatus Say g. pseudolimnaeus Bousfield Arachnoidea R Acari Lebertiidae Lebertia sp. continued 134 Table 20--continued Hygrobatidae Hygrobates sp. Mideopsidae 0.1122225. Spa Pionidae Forelia sp. Unionicolidae Neumania sp. Insecta Ephemeroptera Heptageniidae Mm SP: Diptera Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Parachironomus sp. Polypedilum sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Ceratopogonidae Palpomyia sp. 135 Figure 29. Oligochaeta and Chironomidae seasonal distribution in the reservoir for l973 (values are average of the total nine Ponar grab samples taken each sampling day). 136 Annelida: Oligochaeta (9 samples) — Diptera: Chlronomldae (9 samples) -—- 800- d4I) 600. .430 -25 NE 400'. \ .D I \ E I \ 3 I, \\ 2: \ c / \ 415 g T :E ZCH) -d0 ...T 15 ..4 50 .2 I ' u I :3 l I; I so) I .3 I MAY JUNE JULY AUG. SEPT oer l973 Figure 29 Mean Number 137 Table 21. Taxa and Number of Oligochaeta in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three Sample Total) 1973 Season Stations 5/11 6/19 7/18 8/30 10/10 Total l Limnodrilus sp. 0 16 26 44 86 Peloscolex sp. 0 2 2 18 22 Tubifex sp. 0 0 8 8 26 42 Immature forms 0 0 8 10 48 66 Undeterminable 0 0 18 20 37 75 4 Limnodrilus sp. 0 l 10 56 18 85 Peloscolex sp. 0 0 6 l8 2 26 Tubifex sp. 0 0 14 34 14 62 Immature forms 0 l 12 32 10 55 Undeterminable O O 13 38 6 57 6 Limnodrilus sp. 0 0 0 3 28 31 Peloscolex sp. 0 0 0 4 l0 14 Tubifex sp. 0 0 l l 36 38 Immature forms 0 1 0 4 22 27 Undeterminable 0 0 0 1 32 33 Figure 30. 138 Amphipoda and Acari seasonal distribution in the reservoir for 1973 (values are average of the total nine Ponar grab samples taken each sampling day). 139 Amphipoda (9 samples) —— Acari (9 samples) --- 4o. ‘ 9 I l I I I N I] E 20.. I t I 3 I E [I 3 I Z ,. / 5 II, ” 9 2 I I I IOL ’I I I I I I I I I I 5- ’I I I I I I I g AI I, j I l / l I / .. ~I U ml H I MAY JUNE JULY AUG. SEPT oc1; ISYIB Figure 30 Mean Number 140 N _ m P _ o o o o o o o o sweeten mm _ o o o o o o o o _ o o o asascew_om=awm ”m ON F o o o o 0 ON P o o o o mssswumaa .m o N o N o o o o mwcwcas mm a o o F m o o mammcempouswma nw om o o 0 ON 0 o aspmNUmec .u m a _ N N o o _ o o o o o o mwc_cce mm _ o o o o o o _ o o o o o msmscem_ou=mma ”w m _ o o o o o N o o F N o assessmec .u s _ N o o o o o mwgwees mm n o o P c o m mammcsw_ou:mwm HM mm o o 0 ON N_ _ mapmwomec .o N o o o o o o o mNCNNNm mm m o m N F o o mammcewpovzwwm mm 02 o N m s m o mapswumsc .u N N _ _ _ P o o o o o o o o mNCNNcm mm o o o o o o o o o s o N o msamcENpoesmma mm mm o o N o m o _ o eN o N o masseummc .w P apa_a Nazca m_\F_ Np\o_ o_\op _N\m om\m N_\N N_\N NNN m_\o sxo __\m mcoepmsm .u_:z Fmpop wpm_a wpmfia meoa mpm_a cmcoa mumpa cmcoa opm_a cocoa mum—a cocoa _NSOH .s_:z .NFsz .ppsz .N_=z .323: .Nst AFNNoh mFQEmm mmcgh m m? xmo mcwpaEmm :omm co cowumpm somm com co_pwmoqeou nmco Locoav mkmp com mmPQEmm mpmym mFa?N_:z new Dace Luzon cwo>gmmom cw muoawgae< mo cmnssz new mxmk .NN mppoh 141 Acari Water-mites increased toward the end of the first season (Figure 30) with Lebertia sp., Hygrobates sp., Mideopsis sp., Forelia sp. and Neumania sp. in the Ponar grab samples. Lebertia sp., Hygrobates sp. and Mideogsis sp. were the predominant forms found in the reservoir (Table 23). Ephemeroptera One ephemeropteran nymph, Stenonema sp., was collected in June from the south end of the reservoir. Chironomidae Chironomids collected in the Ponar grab samples increased through- out the first season (Figure 29). Chironomus sp. and Cryptochironomus sp° dominated the samples (Table 24), Ceratopogonidae One Palpomxia sp. larva was collected in the first series of Ponar grab samples on May ll, 1973. This incidental organism had PTOb- ably been blown into the reservoir. Reservoir Multiple Plate Samples October, 1972 to April, 1973 Oligochaeta and Chironomidae Oligochates and chironomids were the first two groups taken after filling of the reservoir on October 23, 1972, by three multiple plate samplers on April 5, 1973 (Table 25). One Limnodrilus sp. and an immature oligochaete, along with one Chironomus sp. were collected in 142 Table 23. Taxa and Number of Acari in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three Sample Total) fi_,1973 Season Stations 5/11 6/19 7/l8 8/30 10/10 Total 1 Hygrobates sp. 0 O O l 2 3 Lebertia sp. 0 O 0 O l 1 Mideopsis sp. 0 O 0 2 O 2 Forelia sp. 0 0 0 O l 1 Neumania sp. 0 O O 0 l 1 4 Hygrobates sp. 0 0 0 l O 1 Lebertia sp. 0 O 0 O O 0 Mideopsis sp. 0 O O O l l Forelia sp. 0 O O O 0 O Neumania sp. 0 O O 0 O 0 6 Hygrobates sp. 0 O l l l 3 Lebertia Sp. 0 0 O l 2 3 Mideopsis sp. 0 O 0 O 2 2 Forelia sp. 0 0 O O 1 l Neumania sp. 0 O O O 0 O Table 24. Taxa and Number of Chironomidae in Reservoir Ponar Grab Samples for 1973 (Composition for Each Station on Each Sampling Day is a Three Sample Total) 1973 Season Stations 5/11 6/19 7/18 8/30 lO/lO Total 1 Chironomus sp. 0 2 15 11 31 59 Cryptochironomus sp. 0 l 4 3O 53 88 Polypedilum sp. 0 O 2 5 14 21 Parachironomus sp. 0 1 0 2 l6 l9 Glyptotendipes sp. 0 O O 7 20 27 Procladius sp. 0 l 6 9 17 33 Conchapelopia sp. 0 O 4 2 14 20 4 Chironomus sp. 1 2 7 58 12 8O Cryptochironomus sp. 2 3 8 95 27 135 Polypedilum sp. 0 l 10 25 0 36 Parachironomus sp. 0 O O 33 0 33 Glyptotendipes sp. 0 O 6 39 9 54 Procladius sp. 0 l l 20 2 24 Conchapelopia sp. 0 l 0 8 0 9 6 Chironomus sp. 2 3 6 4 39 54 Cryptochironomus sp. 0 l 5 5 23 34 Polypedilum sp. 0 l 2 l 13 17 Parachironomus sp. 0 O O O 9 9 Glyptotendipes sp. 0 l 4 2 15 22 Procladius sp. 0 1 l l 21 24 Conchapelopia sp. 0 0 1 O 8 9 144 Table 25. Taxa and Relative Abundance of Reservoir Benthic Macroinverte- brates in October, 1972 to April, 1973 Multiple Plate Samples (3 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-lOO% Annelida Oligochaeta ' C Plesiopora Tubificidae Limnodrilus sp. Arthropoda Insecta C Diptera Chironomidae Chironominae Chironomus sp. 145 the multiple plate sample from the north end of the reservoir. One Chironomus sp. was sampled from the multiple plate sampler in the middle of the reservoir. These four organisms were the only Specimens col— 1ected from the reservoir for the first months of water impoundment and reservoir operation. Reservoir Multiple Plate Samples April to August, 1973 2 III Eighteen multiple plate samplers were placed in the reservoir on April 10, 1973, with three at each of the six reservoir stations. One sampler was removed from each station on June 4, July 6, and August 13 during 1973. The benthic organisms collected on these samplers reflect the colonization of the reservoir during two, three and four month periods (Table 26). Oligochaeta Oligochaetes increased to their highest level in July with sub- stantially lower numbers than the Ponar grab samples indicating that these organisms are primarily ig_the sediments (Figure 31). The oli- gochaete population composition in the reservoir was similar to the Lake Michigan samples with Limnodrilus sp., Peloscolex sp., Tubifex sp., and immature forms (Table 27). Many oligochaetes were undeterminable in these samples due to decomposition and staining. Hirudinea Two leeches were collected in the June samples from the south end of the reservoir. 146 Table 26. Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in April to August, 1973 Multiple Plate Samples (18 Samples) A. Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-100% Annelida Oligochaeta C Plesiopora j Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Hirudinea R Arthropoda Eucrustacea Malacostraca Isopoda R Asellidae Asellus sp. Amphipoda R Gammaridae Gammarus fasciatus Say g, pseudolimnaeus Bousfield Arachnoidea C Acari continued 147 Table 26--continued Lebertiidae Lebertia sp. Hygrobatidae flygrobates sp. Mideopsidae Mideopsis sp. Pionidae Forelia sp. Unionicolidae “32% Spa Insecta Collembola Entomobryidae Ephemeroptera Heptageniidae Stenonema sp. Trichoptera Rhyacophilidae Rhyacophila sp. Hydropsychidae Hydropsyche sp. Coleoptera Dytiscidae R continued 148 Table 26--continued Diptera Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Parachironomus sp. Polypedilum sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Physidae Physa sp. 149 Figure 3l. Oligochaeta and Acari seasonal distribution in the reservoir for l973 (values are average of the total six multiple plate samples taken each sampling day). Mean Number/m2 N O I 150 Annelida: Oligochaeta (6 samples) —— Acari (6 samples) --- -75 1 & O s 1 ol 0 IO. 4 g [:3 1 APRIL MAY JUNE JULY AUG. Figure 3] I973 M e an Number 151 Table 27. Taxa and Number of Oligochaeta in 1973 Multiple Plate Samples from Reservoir Sampling Stations 1973 Season Stations 4/5 6/4 7/6 8/13 9/21 10/17 11/13 Total 1 Limnodrilus sp. 0 O 5 4 32 O O 41 Peloscolex sp. 0 O 3 2 12 O O 17 Tubifex sp. 0 O 4 2 34 O O 40 Immature forms 0 O 15 6 108 1 O 130 Undeterminable O O 5 2 44 O O 51 2 Limnodrilus sp. - O 14 O 0 1 O 15 Peloscolex sp. - O 8 O O O 0 8 Tubifex sp. - O 10 O O 3 0 13 Immature forms - O 36 O O 2 O 38 Undeterminable - O 12 O O 0 O 12 3 Limnodrilus sp. - O 2 O 1 1 2 6 Peloscolex sp. - O 1 0 1 O 1 3 Tubifex sp. - O l O 3 O 1 5 Immature forms - O 4 2 2 O 2 10 Undeterminable - 0 5 l 1 O 3 10 4 Limnodrilus sp. 0 O 1 0 12 O 1 14 Peloscolex sp. 0 O 2 0 6 O O 8 Tubifex sp. 0 O 2 O 8 l O 11 Immature forms 0 O 6 O 18 O 2 26 Undeterminable O 0 4 O 4 0 l 9 5 Limnodrilus sp. - O 32 1 10 7 - 5O Peloscolex sp. — O 26 O 2 3 - 31 Tubifex sp. - O 34 1 l4 8 - 57 Immature forms — l 104 2 6 5 - 118 Undeterminable - O 48 1 1 7 - 57 6 Limnodrilus sp. 1 O 22 O 7 6 2 38 Peloscolex sp. 0 O 10 0 6 1 O 17 Tubifex sp. 0 O 18 O 5 5 3 31 Immature forms 1 O 62 O 5 7 2 77 Undeterminable 0 O 31 O 7 17 1 56 152 Isopoda Isopods increased to their highest level in August after four months colonization of the samplers (Figure 32). Asellus sp. were the only isopods found in the samples and the rapid increase indicates their establishment in the reservoir. Amphipoda Amphipods showed a rapid increase with the highest level also in August (Figure 32). Gammarus fasciatus and G, pseudolimnaeus were the two forms present with g, fasciatus approximately eight times more abundant (Table 22). M1. The water-mites increased to an average number of 34 in August (Figure 31). Lebertia sp., Hygrobates sp. and Mideopsis sp. were the major forms with Forelia sp. and Neumania sp. present in less abundance (Table 28). Collembola Twenty-nine Entomobryidae were collected by the multiple plate samplers. Entomobryidae are terrestrial usually found in dead bark or decaying wood, and secondarily in the upper soil layers. They probably blew into the reservoir and were on the water surface when the multiple plate samplers were pulled out of the water. Ephemeroptera Three ephemeropteran nymphs, Stenonema sp., were collected by the plate samplers from the reservoir. 1.5.2511: IA. Figure 32. 153 Chironomidae, Amphipoda and Isopoda seasonal distributicni in the reservoir for 1973 (values are average of the total six multiple plate samples taken each sampling day). 154 Diptera: Chlronomldae (6 samples) — Amphipoda (6 samples) ..-..- 2° *- Isopoda (6 samples) —..- Mean Number/m2 m I 00’ .o I ..___...--""‘. I: r. | .3 APRIL MAY JUNE JULY AUG I973 Mean Number Figure 32 155 Table 28. Taxa and Number of Acari in 1973 Multiple Plate Samples from Reservoir Sampling Stations 1973 Season Stations 4/5 6/4 7/6 8/13 9/21 10/17 311/13 Total 1 Hygrobates sp. 0 O l 9 O 2 l 13 Lebertia sp. 0 O O 4 O O 1 5 Mideopsis sp. 0 O O 7 O 2 0 9 Forelia sp. 0 O O 2 O 1 1 4 Neumania sp. 0 O O O O 0 l l 2 Hygrobates sp. 0 O O O 3 3 2 8 Lebertia sp. 0 O O O l 2 4 7 Mideopsis sp. 0 O O O 2 l 2 5 Forelia sp. 0 0 O 0 l 0 l 2 Neumania sp. 0 O 0 O O 1 O 1 3 Hygrobates sp. 0 O 0 3 O 4 2 9 Lebertia sp. 0 O 0 11 O 7 3 21 Mideopsis sp. 0 O O 6 O 3 O 9 Forelia sp. 0 O O l O l l 3 Neumania sp. 0 O O l 0 0 0 l 4 Hygrobates sp. 0 O O 31 l 0 5 37 Lebertia sp. 0 0 O 22 O O 3 25 Mideopsis sp. 0 0 0 17 O 0 8 25 Forelia sp. 0 O O 6 O O O 6 Neumania sp. 0 0 0 l O 0 0 1 5 Hygrobates 5p. 0 O O 18 0 1 - l9 Lebertia sp. 0 O O 9 O O - 9 Mideopsis sp. 0 O 0 21 l 3 - 25 Forelia sp. 0 O O 9 0 O - 9 6 flygrobates sp. 0 O O 10 3 6 4 23 [Ebertia sp. 0 0 O 18 2 8 16 44 Mideo sis sp. 0 O 0 15 l 3 12 31 Forelia sp. 0 O 0 5 2 2 7 16 Neumania sp. 0 0 O 4 l O 2 7 156 Table 29. Taxa and Number of Chironomidae in 1973 Multiple Plate Samples from Reservoir Sampling Stations 1973 Season Stations 4/5 6/4 7/6 8/13 9/21 .10/17 11/13 .Total l Chironomus sp. CryptoChironomus sp. Polypedilum sp. Parachironomus sp. Glyptotendipes sp. Procladius sp. Conchapelopia sp. 2 Chironomus sp. Cryptochironomus sp. Polypedilum sp. Parachironomus sp. Glyptotendipes sp. Procladius sp. Conchapelopia sp. - 3 Chironomus sp. — Cryptochironomus sp. - Polypedilum sp. - Parachironomus sp. - Glyptotendipes sp. - Procladius_sp. - Conchapelopia sp. - 4 Chironomu§_sp. Cryptochironomus sp. Parachironomus sp. Glyptotendipes sp. Procladius sp. 5 Chironomus sp. Cryptochironomus sp. Polypedilum sp. Parachironomus sp. Glyptotendipes 5p. Procladius sp. OOOOOOO O—‘-—‘OO-—*l\> OOOOONO dNON—‘LON N—‘NOOU‘IN OOOOOOO OOOOO-‘O d-‘OOOLo-d COO-“OOH O-J-D-OOKDOW _lpa—lO—Jn—IV OOOOOOO oo—Io—Iw—a OOOOON-fl HOOOOOO NN-fiO-JNN NNONOU‘ICD OOOOOON ONOOOH" OOOO-fl Dodo-DOS Need-4N -'OO|\)\J 00000.) 00000 00000 (IND-“NO l l I I I OOOOUWO dNO-HN-b OONOKDN '—‘OOO—'O COCO-JO I I I I I I NNNHCDG continued Table 29--continued 157 _32 1973 Season Stations 4/5 6/4 7/6 8/13 9/21 lO/l7 11/13 Total 6 . Chironomus sp. 1 2 7 l 2 2 0 15 Cryptochironomus sp. 0 1 O 7 1 ' 1 O 10 Polypedilum sp. 0 l O O O O O l Parachironomus sp. 0 O l O 0 O O l Glyptotendipes sp. 0 2 O O O 1 O 3 Procladius sp. 0 O 2 2 2 1 O 7 Conchapelopia sp. 0 1 O 0 O O 0 l 158 Trichoptera Ten trichopteran larvae were collected with Rhyacophila sp. and Hydropsyche sp. the two genera present in the samples. Coleoptera One adult Dytiscidae was taken from the reservoir by the multiple plate samplers. This aquatic beetle, approximately 40 mm in length, probably flew into the reservoir from one of the surrounding lakes. Chironomidae The chironomid larvae increased to an average number of l7/m2 in August (Figure 32). These chironomids were dominated by Chironomini genera, similar to the reservoir Ponar grab samples (Table 29). Gastropoda Nine gastropods, Physa sp., were taken from the reservoir in August after four months colonization of the samplers. The multiple plate samplers either selectively collected Physa sp., or there were no other gastropods in the reservoir. Reservoir Multiple Plate Samples June to September, 1973 The six multiple plate samplers, placed one at each station in June, were allowed to colonize for three months and were lifted in September (Table 30). Oligochaeta The oligochaetes dominated the samples with the majority found in the south end of the reservoir. Many immature and undeterminable forms 159 Table 30. Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in June to September, 1973 Multiple Plate Samples (6 Samples) Relative Abundance: Numerical percentages of total number of benthic macroinvertebrates in all benthic groups. R (rare) = o-25% A (abundant) = 51—75% C (common) = 26-50% VA (very abundant) = 76-lOO% Annelida Oligochaeta A Plesiopora Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Arthropoda Eucrustacea Malacostraca Isopoda R Asellidae Asellus Sp. Amphipoda R Gammaridae Gammarus fasciatus Say 9, pseudolimnaeus Bousfield Arachnoidea R Acari Lebertiidae continued 160 Table 30--continued A Lebertia sp. Hygrobatidae Hygrobates sp. Mideopsidae Mideopsis sp. Insecta Ephemeroptera R Heptageniidae Stenonema sp. Trichoptera R Rhyacophilidae Rhyacophila sp. Hydropsychidae Hydropsyche sp. Diptera R Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Parachironomus sp. Polypedilum sp. Glyptotendipes sp. continued 161 Table 30v-continued Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Physidae Physa sp. 162 along with Limnodrilus sp., Peloscolex sp. and Tubifex sp. were found in these samples. Isopoda The majority of the isopods, Asellus sp., was collected at the north end of the reservoir. Gastropoda The majority of the gastropods, Physa sp., was sampled at the north end of the reservoir. Reservoir Multiple Plate Samples July to October, 1973 The six multiple plate samplers, placed one at each station in July, were allowed to colonize for three months and were lifted in October (Table 31). Oligochaeta The oligochates sampled during this period came almost entirely from the north end of the reservoir with Limnodrilus sp., Peloscolex sp. and Tubifex sp. along with immature and undeterminable forms present in these samples. Isopoda Asellus sp. were most abundant at the north end of the reservoir. Gastropoda Gastropoda, Physa sp., was the most abundant benthic macroinverte- brate group in these samples. 163 Table 31. Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in July to October, 1973 Multiple Plate Samples (6 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = O-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-lOO%- ' Annelida Oligochaeta C Plesiopora Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Arthropoda Eucrustacea Malacostraca Isopoda C Asellidae Asellus sp. Amphipoda R Haustoriidae Pontgporeia affinis (Lindstrom) Gammaridae Gammarus fasciatus Say g, pseudolimnaeus Bousfield continued 164 Table 3l-—continued Arachnoidea R Acari Lebertiidae Lebertia sp. Hygrobatidae Hygrobates sp. Mideopsidae Mideopsis sp. Pionidae Forelia ap. Insecta Ephemeroptera R Heptageniidae Stenonema sp. Trichoptera R Rhyacophilidae Rhyacophila_sp. Diptera R Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. continued 165 Table 31--continued Parachironomus sp. Polypedilum_sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Physidae Physa sp. 166 Reservoir Multiple Plate Samples August to November, 1973771 The six multiple plate samplers, placed one at each station in August, were allowed to colonize for three months and were lifted in November (Table 32). Only five samplers were available to be lifted and analyzed. Isopoda Asellus sp. were the only isopods collected, being most abundant at the north end of the reservoir. Amphipoda Pontoporeia affinis was the only amphipod in these samples; Gammarus fasciatus and g, pseudolimnaeus had dominated the multiple plate samples earlier in the season. Acari The water-mites, Lebertia sp., Hygrobates sp., and Mideopsis sp., were the most abundant benthic macroinvertebrates in these samples. They were concentrated at the north end of the reservoir. Gastropoda Physa sp. were also concentrated at the reservoir's north end. 167 Table 32. Taxa and Relative Abundance of Reservoir Benthic Macro- invertebrates in August to November, 1973 Multiple Plate Samples (5 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = O-25% A (abundant) = 51-75% C (common) = 26-50% VA (very abundant) = 76-lOO% Annelida Oligochaeta R Plesiopora Tubificidae Limnodrilus sp. Peloscolex sp. Tubifex sp. Arthropoda Eucrustacea Malacostraca Isopoda R Asellidae Asellus sp. Amphipoda R Haustoriidae Pontoporeia affinis (Lindstrom) Arachnoidea C Acari Lebertiidae Lebertia sp. continued 168 Table 32—-continued Hygrobatidae flygrobates sp. Mideopsidae Mideopsis sp. Insecta Ephemeroptera R Heptageniidae Stenonema sp. Trichoptera R Rhyacophilidae Rhyacgphila sp. Hydropsychidae Hydropsyche sp. Diptera R Chironomidae Chironominae Chironomus sp. Cryptochironomus sp. Polypedilum sp. Glyptotendipes sp. Tanypodinae Procladius sp. continued 169 Table 32--continued Mollusca Gastropoda Pulmonata Physidae EDX§§.5P- *2' 170 Reservoir Rock Basket Samples on Scour Protection Area The rock baskets on the scour protection in the reservoir were sparsely colonized (Table 33) compared to the rock baskets on the jetty and breakwall in Lake Michigan. On the scour protection, chironomid 2 larvae reached an average of 15/m . Oligochaetes, gastropods, and water—mites were found occasionally in the rock basket samples (Figure 33). Reservoir Benthic Macroinvertebrate Colonization and Development The reservoir population composition of three selected months June, August, and October, indicated the direction the macroinverte- brate population was developing. In June, chironomids dominated the population although the average total number of individuals was relatively low (Figure 34). The oligo- chaetes were the next most abundant group in the Ponar grab samples and amphipods the second most abundant on the plate samplers. The August population composition in the Ponar grab samples was dominated by oligochaetes and chironomids with the average total number of individuals reaching approximately 1,200/m2 (Figure 34). The multiple plate samples presented a population which was more diverse in the number of different invertebrate groups with the water-mites the most abundant followed by the chironomids, isopods, and amphipods. The total number of individuals in the multiple plate samples was substantially less than in the grab samples. 171 Table 33. Taxa and Relative Abundance of Reservoir Benthic Macro» invertebrates in 1973 Rock Basket Samples (15 Samples) Relative Abundance: Numerical percentage of total number of benthic macroinvertebrates in all benthic groups. R (rare) = 0-25% C (common) = 26-50% A (abundant) = 51-75% VA (very abundant) = 76-lOO% Annelida Oligochaeta Plesiopora Tubificidae Limnodrilus sp. Tubifex sp. Hirudinea Arthropoda Arachnoidea Acari Libertiidae Lebertia sp. Hygrobatidae Hygrobates sp. Mideopsidae Mideopsis sp. Insecta Diptera Chironomidae continued 172 Table 33--continued Chironominae Chironomus sp. Cryptochironomus sp. Pglypedilum sp. Glyptotendipes sp. Tanypodinae Procladius sp. Conchapelopia sp. Mollusca Gastropoda Pulmonata Physidae Physa sp. Figure 33. 173 Oligochaeta, Chironomidae and Acari seasonal distritnrtion in the reservoir for 1973 (values are average of the total four rock basket samples taken each sampling day). 201- I4p I2p O I Mean Number/m2 174 Annellda: Ollgoahaeta (4 samples) -— Dlptera: Chlronomldae (4 sanples) --- ‘ Acari (4 samples) —-- II,“ II \ I II \‘ I, ‘\ I 1‘ ’ \ I, 1‘ I \ I \ I \ I \ I \ I \ I \ I \ I, \ \ I \ I \ I \ I, \\ I \ I, \ I \ I I 1 ° \ \ \ \\ M ./ \ \, -'/ I 1. ../ \ 3 .-/ \‘ / ’ : JUN gfi I 231 OCT NOV. JULY AUG. 738E” Figure 33 19 Mean Number 175 .Axmv chPQEmm comm msmwcmmco gmnszc _mpop mmmcm>m mg» m? 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NN N NNNz N NNN N ..NNNZ N NNN: N NNNN N NNNz N NNNz N NNNNNNNN NNNINN NNNNNNNNNN NN NNNNNNN NNNNNNZNNNIN NNNNN NNNNNNNNN NNNNNNNNN NNNNNNNNNNN ONNONN mm4az:_.oguw=_ “—.0 (52:5: Umme>cou u NE\Z mwFQEwm Cw mwuwgnwuLngwogqu k0 Lana—5: u c wwwczvzgw: ...... .LwI mmvomewz u .Emz N.NNINN.Emz O O O O O.NON NN O O 0.0N N O O O.NON NN N.Emz O.NON N 0.0N N 0.0NON NO O.NO O 0.0N N O O O.NO.N NNN O O O O O O.NOO Om N.OO m O.NO N O O O.NNON NN 0.0N N O O N.OOm ON 0.0N N 0.0N N O O N.OOmN NN N.OO O O O 0.00NN NO 0.0N N 0.0N N O O N.NNON NON O O O O O O.NO O N.OO O O O O O 0.00N ON O.NO N O.NO N O O O O 0.000 NO O O N.ONN NN N.Emz N.NNN O O.NON N O O O O O.NNON NN O O 0.00N ON N O O N.ONN O O O O O N.ONO ON O O 0.00m NN I I I l l l l I I l O O l I O.NNINO.Emz N.ONN O O O N.ONN NF O.NON NF O.NON NN O O O.NNNN ON m O.Emz O.mON ON O O m.ONO NN N.NON O 0.00m NN O O m.ONNN NNN O O O O N.NON ON 0.0N N N.OO O O O O.NNO ON O O O O m.ONO NN N.OO O O O O O O.NNO NN N O O O O O.NON NN 0.0N N O O O O O.NNm NN 0.0N N O O O.mON ON O.Nm N N.OO O O O O.NON NN m.Emz O.NO O 0.0N N O.NNO NN O.NO N 0.0N N O O O.NOO NO N N.Emz O.NON NN 0.00N ON O.NOO Om N.ONN O O.NO O O O O.NOO Om : NENZ a ENZ : NE\z : NENZ : NENZ : NE\z c NENZ c OZOHNOOOOO coo we Om\mmpmgn smpgm>cNoLumE No Lassa: cwpgm>cou n NE\z mmNQEmm :N mmumgnougw>cNogoms No gangs: u : “cucumEmz u 4km: O O O O N.ONO ON 0.0N N OOON N O O O.NNO Nm N .Emz OowN N O O N.ONN mN 0.0N N O O O.wN N O.NNO NN O O O O O 0.000 ON O.NO O O.wN N O O 0.0NNN NO O.NON N 0.0N N NOONm ON O.NO N O.NO N O O 0.000N NNN O.mN N O.NO N N.NON ON N.ONN O O O O O N.OOON OON O O.NNO NN N.ONN O N.NON mN O.NO O OONO O O O O.NNON NON 0.0N N O O O.NO O O.NO N O.NNN NN O O N.NON mN N .Emz OemN N 0.0N N N.OO m 0.0N N N.OOON mm O O m¢OOO NO N N .Emz 0.0N N 0.0N N N.OO m O.NO N N.ONON mmN O O O.Nmm NN O.NON N O.NO O N.ONN O 0.0N N wonm N O O O.NONN NO O.NO N 0.0N N N.Nom ON OOON N O.wN N O O NOOOON OO O 0.00N ON O.NO N OONON NN N.NON m 0.0N N O O O.NOO Nm O O OOON N O.NON NN O O O O O O OONO O O O O O OOOOm NN 0.0N N O O O O 0.00N ON N O O O O w.mON NN OON N OON N O O N.ONN O maNNm NN O.mON NN 0.00N ON N.OO m OOON N O O monN N N “Emz OONON NN OOOOO Nm O.mwN ON O.NO O N.NON O O O mgONN NN N N ”Emz NomNN O O.NOO Om N.ONm ON N,OO m O.NO O O O Oowmm ON : E\z : E\z : NE\z : NE\z : E\z : NE\z : NE\z : OZONNOOOOO coO ”E Nm\mmumgnmpgm>cNogowE No Lenszc umpgm>coo mmNasmm cN mmumgnmpgm>cNoLqu No L¢OEgc u : magwpaogoNgN u .oNgN ”mmumuNmNz u .mNz II N E \ Z ’ ON .mxz O.NNN N.NON O.NON NN chOON NmN N.OO 0.000N NON N ON OOON N w m m .mxz N.OO m O.Nm N OONO O O.mN N O.wa NN 0.0N N O.mON NN O O 0.0N N 0.000 Nm 0.0N N mon N O O O.NNN ON O O O O N.OOm ON N.ONN O N.OO O O O N.NON m m NOOO m O.NO O OLNNN ON O.NO O O.NO N O O O.NNO ON O O O O N.OONN OO O O O.wN N O O O.mNm ON O O O O O.NOO Om O O O.NO N O O N.NOO ON N O O O O m.OOO Nm O O OUON N O O N.NON ON OoNOO Om N.ONON Ow O.NNN ON 0.0N N NQNON O O O N.NON ON N OONLN OONOO Nm O.NOON NON N.NOO ON O.NON N O.mwN ON O O N.NmN Om N N .UNLN N.ONON Ow 0.0NNN NmN O.NNO NN O.mN N m.ONO NN O O momww NN : NE\z : NENZ : NE\z : NE\z : E\z : ENZ : NE\z : OZONNNNO ONOINO OOOOO cou ME OmNmmumgnmpgm>cNoLomE No Lmnszc umggm>cou u NE\z mmNOEmm :N mmpmgnmpgm>cNogomE No LmOEOc u c monoqmumO u .umO mmcoaomN u .OmN «accumEmz u .Emz NOON Nm N.NN NN m.o N N.N m m.o N N.mN ON m.m NN O o o m.o N o o o o o o Nam N m.o N N N .OmN m.m oN mchm Nam w.N m m.o N N.NNN mwN N.NN NN N.N m m m.m ON N.NNN mmN one N moo N N.OON mNN o.m m o o N N coma mN Damz Nam N N mom wNm o o o o N.NNN NNN moo N muN N N : Ns\z : E\z c NENZ : Ne\z c NENZ N NENZ : NENZ N mzoNNNNm ONOINO :ou ME NmNmmpmgamuLm>cNoLumE No L¢OE:: Ompgm>cou u NE\z mwNaEmm :N mapmgnmme>cNogomE No gangs: u : :63 o o mom N N.NN mo N.N N N.NNN mm NoN N N.N N N.N N -NNNNN NNNNNNO 199 NNNNN m.N N NON N N.NN NN o o N.NN Om NQN N N.N N NON N NNNom NNNNNNO NN\z N NNNZ N Nz\z N NN\z N NNNZ N NNNZ N NNN N Ne\z N mzoNNNNm NNONONNNNN NNNNZOZONNIN NNNNNOINNNN NNNNN NOONNINEN NNoNomN N ZNNNNN: NNNNINONNNO mNNNN\O OOOOEcoO we NmNmmngnmpgm>cNoLumE No gangs: Omagm>cou n NE\z mquEmm cN mmpmgnmpxm>cNogome No NOOEOc u : VII! O O 0.0 N O O O O O O O O O.N N O O O O O O O O O O O O O O O O O O 0.0 N O O O O O O O O O O N O O O O O O O O O O O O O O O O O O O O O O O O O O O O O N O O O O O O O O O O O O O O N c ENZ : NE\z : ENZ : NE\z c NENZ : NE\z : NENZ : OZONNNOOON 206 OO.O u NE\z LoN Louumm conLm>coO ms Nm\mmpmgampgm>cNogums No gangs: 2 mmeuOonEmOOO u .sgm machnng: u .NN: Ompgm>cou n NE\z mmNaEmm :N mmpmgnmpgm>cNogumE No gmaszc O O N.O N O O O O O O O O O O O O O N.N O O O O O O O O O 0.0 N O N .gam mN .NN: O O O.NN NN O O O O N.N N O O O O N N .NN: O O N.N O O O O O N.N m 0.0 N O O O O O N.O O O O O O O O O O O O N O O N.N O O O O O N.N O O O O O N c NE\z : NE\z c E\z : NE\z : NE\z : NENZ : NENZ : OZONNNNO OOOINO NOOON 207 OO.O u me\z Low Lopumw congm>=oO ms Nm\mmumgnmpgm>cNogume No LmOENO umugm>cou u NE\z mmNaEmm :N mmpmgnmpgm>z axons No gunssc c magmpaogmsmzam u .gam mmNoOEmNNoO u .NoO O .NOO O O O.w ON 0.0 N O O 0.0 N 0.0 . N O.NNN NNN O O O 0.0 ON O O O O O O O.w O N.NNN NNN O O O O.NO O 0.0 N O O O O N.NN ON N.ON ON N NN .NOO O O 0.0 N O O O O N.ON NN N.N m O.NN ON m N .cam O O O.N N 0.0 N O O N.N O O O N.NN Ow N m .NOO O O N.N N O O 0.0 N O.NN ON O O O.NN Nm N : E\z : ENZ : NENZ c NE\z : NE\z : NENZ c NE\z : OZONNNOOON 208 sogume No gangs: umpgw>cou OO.O u Ns\z LOO Nouomm :onNm>:oO ME Om\mmpwgnmpgw>cN u Ns\z mmNaEmm cN mmpmgampgm>cNoNome No Lm353= u c magmpaongmcaO u .gam N .LOO O 0.0 ON O m.ON NO O.NN ON O.m N O O O O O.NN ON O N.OO NO N.ON mm O.N N N.N O O 0.0 O.NN ON 0.0 0.00 NN N.N O O.NN ON O O N m.O O.NN ON O 0.0N NN N.NN NN N.Nm Om N.N m m 0.0 O.NN ON 0.0 O O N.N O N.N O O O N 0.0 O.NN NN N.N 0.0N NN 0.0 N 0.0 NN N.NN ON N : E\z : E\z : ENZ : NENZ c NE\z : NE\z : NENZ c OZONNmOOOm 209 E\z goN Louumm conLm>cou ms Om\mmgwgnmpgm>cNogumE No Lanes: Ompgm>coo u NE\z mmNOEmm cNOmmmNHOmugm>cNogume No gmne:c u : N0.00 OO ON.N O O0.0 N N0.0 O O O OO.NN NN ON.ON OO O ON.O N ON.N N O0.0 N O0.0 N O0.0 N O O Nm.ON mm O N0.0 O NO.N m O0.0 N O0.0 N O O ON.N O NN.NN ON N ON.ON Nm N0.0N ON O O O O O0.0 N NN.N O NN.N O m ON.N N ON.ON ON O O ON.O N ON.O N NN.NN ON O O N O O O0.0N NN O O O O NO.N m ON.N O N.NON OON N N NEz N NN.NN N NNNOOON OO.O u Ns\z NoN NopumN :onNm>:oO NE OmxmmpmNnmuNm>cN legume No Nmnszc umNNm>coo u Ns\z NmNQEmm :N mmpmNOmNNm>cNoNuws No Nmasac u : NagmpaonsmngO u .OOO N0.0N ON ON.N O NO.N m N0.0N ON O0.0 N Om.mN ON NO.Nm OO O N .NNN NN.NN NN NN.N N NN.N N NN.N N NN.N N NN.NN NN NN.NN om N no NN.NN ON 0 o NN.N N o o NN.N N NN.N N NN.N N N mu NN.NN mN NN.N N NN.N N NN.NN mN o o NN.NN NN NN.N N N NN.N N o o NN.N m NN.N N NN.N m NN.NN NN NN.N N N NN.N N N N NN.N N NN.N m NN N N NN.N N NN.N N N N NNNZ N NNNZ N NNN N NNN: N NN\z N NNN: N NNNZ N mzoNNNNm ONOINO mmOmm OO.O u NENZ NoN Nopuwm coNNNm>coO NE ON\NmpNNnmpNo>cN IONNNE No NmOEN: umuNm>cou u NE\z NmNaENN cN mmumgnwpgm>cNoNoNE No Lungs: u : NNqunonemgam u .cqm N .NNN NN.NN NN N N NN.N N NN.NN NN NN.N N NN.NN NN NN.N N N - - .. .. - .. - - - .. .. - .. - N 1 NN.N N N N N N NN.NN NNNN.N N N.N NNNNN N N m NN.N NN NN.N N NN.N N NN.N N NN.N NNN.N N NN.N N N NN.N N NN.N N N N NN.N N N N NN.N N N N N NN.N N NN.N N NN.N N NN.N N NN.N NNNN N N N N N N.NN N N.NNN N NN.NN N NEz N NN.NN N NN.NN N NNN N 9555 ONOINO < OOONNONOOON 212 RESERVOIR ROCK BASKET SAMPLES 6/22/73 OLIGOCHA TA HIRUDIN A ACARI CHIRONOMIDAE GASTROPO A STATIONS n N/m n N/m n N/m2 n N/m2 n N/m South Row 1 O 0 0 O 0 0 1 1.3 0 O (nearest intake) 2 O O 0 O 0 O 1 1.3 O O 3 O 0 O 0 O 0 4 5.3 0 O 4 1 1.3 O 0 0 O 3 4.0 0 O n = number of macroinvertebrates in sample; N/m2 = converted number of macroinvertebrates/sq m; Conversion factor for N/m2 = 1.32 213 RESERVOIR ROCK BASKET SAMPLES 8/29/73 OLIGOCHA TA HIRUDINEA ACARI CHIRONOMIDAE GASTROPODA STATIONS n N/m n N/m2 n N/m2 n N/m2 n N/m2 North Row 1 O 0 0 O 0 O 11. 14.5 0 O (nearest intake) 2 O O O O 1 1.3 15 19.8 0 O 3 1 1.3 O O O 0 12 15.8 0 0 4 0 O O O O 0 10 13.2 0 O n = number of macroinvertebrates in sample; N/m2 = converted number of macroinvertebrates/sq m; Conversion factor for N/m2 = l.32 214 RESERVOIR ROCK BASKET SAMPLES 11/7/73 OLIGOCHAETA HIRUDIN A ACARI CHIRONOMI AE GASTROPODA STATIONS n N/m2 n Wm 11 N/m2 n Wm 11 N/m2 Middle 1 0 0 O 0 3 4.0 1 1.3 0 O (nearest intake) 2 0 O 1 1.3 o O 0 0 2 2.6 3 0 0 0 0 0 0 o 0 0 O 4 0 0 O 0 2 2.6 0 0 O O n = number of macroinvertebrates in sample; N/mz = converted number of macroinvertebrates/sq m; Conversion factor for N/mz = 1.32 “-—' 215 RESERVOIR ROCK BASKET SAMPLES 11/13/73 OLIGOCHAETA HIRUDINEA ACARI CHIRONOMIDAE GASTROPO A STATIONS n N/m n N/m2 n N/m2 n N/m2 n N/m South 1 0 0 0 O 2 2.64 0 0 0 o (nearest intake) 2 0 0 o 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 n = number of macroinvertebrates in sample; N/m2 = converted number of macroinvertebrates/sq m; Conversion factor for N/m = 1.32 LITERATURE CITED LITERATURE CITED Alley, N. 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