3'05:- THE ABUNDANCE AND DISTRIBUTION OF BENTHIC MACROINVERTEBRATES IN THE LUDINGTON: PUMPED STORAGE RESERVOIR Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY DANIEL LEE LAWSON 1977 6' /o g" 0...: «3 ABSTRACT THE ABUNDANCE AND DISTRIBUTION OF BENTHIC MACROINVERTEBRATES IN THE LUDINGTON PUMPED STORAGE RESERVOIR BY Daniel Lee Lawson The benthic macroinvertebrate composition and abundance of the Ludington Pumped Storage Reservoir was investigated during the 1974-1975 seasons. Specific information was sought to answer those questions con- cerning the rate of colonization since filling in 1973 and its compar- ative, benthic abundance. Ponar dredge samples were taken monthly from April to October of each year. Hester—Dandy multiple plate samplers, placed in April along a north-south transect, were removed in June, July and August of each year. Combined information yielded significant results. Oligochaeta and Chironomidae comprised the major benthic organisms. Amphipoda, Isopoda and Gastropoda, although much less numerous, were collected regularly. The Ephemeroptera, Hydracarina, Ostracoda, and Pelecypoda were encountered rarely. Significant increases of Oligochaeta, Chironomidae, Amphipoda and Isopoda were found from 1974 to 1975 (P<0.0S). All remaining taxa showed no significant increases during the present studies. Numbers of Oligochaeta, Chironomidae, Amphipoda, Isopoda, and Gastropoda have increased since the first year of reservoir operation. Generic composition of Oligochaeta was dominated by Tubifex sp., Limnodrilus sp. and their corresponding immature categories. Pot- amothrix sp. was first taken in 1974 and appeared to become established in the 1975 collections. Reproductive activity of Tubifex sp. and £137 nodrilus sp. was greatest during the spring while decreasing as summer progressed. The Chironomidae underwent a dynamic shift in generic composition. Chironomus sp., was a major taxa in the mid-1974 collections and domin- ated the Chironomidae samples in 1975. Chironomus sp. was in greater abundance in the south end of the reservoir; its zonation was attributed to calmer waters and ample food supply. Species assemblages of Ludington Reservoir Oligochaeta indicated organic enrichment since operation began in 1973. Peloscolex sp., an oligotrophic indicator, was rarely found in the 1974-1975 collections, while the eutrophic indicator Potamothrix sp. became established. Results indicated an increasingly productive reservoir since fill- ing in 1973. Water currents coupled with organic inputs of fish and in— vertebrates caused by turbine mortality may have been the causitive agent. THE ABUNDANCE AND DISTRIBUTION OF BENTHIC MACROINVERTEBRATES IN THE LUDINGTON PUMPED STORAGE RESERVOIR By Daniel Lee Lawson 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 1977 ACKNOWLEDGEMENTS I wish to express appreciation to Consumer's Power Company for the research Opportunity, financial support, and the excellent field facil- ities. Special gratitude is afforded to Dr. Peter I. Tack for his support, guidance, and wisdom. I also extend my appreciation to my guidance committee: Drs. Charles Liston, T. Wayne Porter, John Gill, and Kenneth W. Cummins for their assistance and counsel throughout this research. The successful completion of any project requires a congenial at- mosphere conducive to research. I wish to thank, in this regard, Dr. T. wayne Porter for the research space, advice and good humor which at times was sorely needed. His friendship was invaluable. My fellow graduate students B. Anderson, W. Duffy, J. Gulvas, R. Hauer, D. Lechel, and F. Serchuk were instrumental in the collection of data and the free exchange of ideas. Similarly, D. Brazo, M. Chaffee, L. Gaylord, B. Hauer, D. Huber, B. Kendall, F. Koehler, and B. Rasher gave of their time. I wish to thank our boat captain L. Yeck for his knowledge and the care be extended to his crew. Special thanks are also extended to Dr. C. Liston for the avail- ability of research materials and computing services. J. Church is similarly thanked for the keypunching of data and typing services. ii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . DESCRIPTION OF AREA . . . . . . . . . . . LITERATURE REVIEW . . . . . . . . . . . . . METHODS AND MATERIALS . . . . . . . . . . . Field and Laboratory Procedures . . . . Subsampling . . . . . . . . . . . . . . . Statistical Analysis . . . . . . . . . . RESULTS AND DISCUSSION . . . . . . . . . . . Ponar Dredge Samples - Major Groups . . . Oligochaeta . . . . . . . . . . . . . Chironomidae . . . . . . . . . . . . Less Abundant Groups . . . . . . . . Ponar Dredge Samples - Generic Composition Oligochaeta . . . . . . . . . . . . . Chironomidae . . . . . . . . . . . Less Abundant Genera . . . . . . . . Hester-Dendy Multiple Plate Samples . SUMMARY AND CONCLUSIONS . . LITERATURE CITED . . . . . . . . . . . . . . APPENDIX . . . . . . . . . . . . . . . . . iii . iv . lO . 13 . 15 15 15 . 19 20 20 20 . 25 . 30 . 3O . 42 . 44 . 49 Table 10 LIST OF TABLES Counts of Five Taxa of Six Replicate Subsamples. Monthly Mean Number/m2 of Major Taxonomic Groups in 1974 Ponar Dredge Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Major Taxonomic Groups in 1975 Ponar Dredge Samples from the Ludington Reservoir. Taxa and Mean Number/m2 of Oligochaeta in 1974 and 1975 Ponar Dredge Samples from the Ludington Reservoir. Taxa and Mean Number/m2 of Chironomidae in 1974 and 1975 Ponar Dredge Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Taxa in 1974 and 1975 Ponar Dredge Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Major Taxonomic Groups in 1974 and 1975 Hester-Dandy Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Oligochaeta in 1974 and 1975 Hester-Dandy Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Chironomidae in 1974 and 1975 Hester-Dendy Samples from the Ludington Reservoir. Monthly Mean Number/m2 of Taxa in 1974 and 1975 Hester- Dendy Samples from the Ludington Reservoir. iv Figure LIST OF FIGURES Aerial View of the Ludington Reservoir and Sampling Stations. Modified Ponar Wash Screen and Compartmented Fiberboard Divider in Place for Subsampling. Cumulative Percentage of Total Oligochaeta due to each Taxon for each Sampling Interval in the 1974-1975 Ponar Dredge Samples. Cumulative Percentage of Total Chironomidae due to each Taxon for each Sampling Interval in the 1974-1975 Ponar Dredge Samples. Seasonal Abundance of Gammarus sp. (Amphipoda) in the 1974 and 1975 Hester-Dendy Samples. Seasonal Abundance of Asellus sp. (Isopoda) in the 1974 and 1975 Hester-Dandy Samples. INTRODUCTION In response to increasing electrical demands, hydroelectric gener- ating facilities have been constructed to insure adequate power pro- duction. These facilities require environmental assessment of possible effects to the local ecological balance. In such a case the Consumers Power Company contracted with the Michigan State University, Department of Fisheries and Wildlife in 1971 to assess the effects of the Ludington Pumped Storage Project upon the Lake Michigan biota. The investigations of benthic macroinvertebrate colonization of the Ludington Reservoir is one phase of a larger study, that includes studies of the effects upon the physio-chemical conditions, as well as fish, benthic and planktonic organisms (Liston and Tack, 1973). A sim- ilar study, summarized in depth by Olson (1974,1975), reported the benthic macroinvertebrate colonization of the Ludington Reservoir during the first year of existence in 1973. This research conducted in 1974 and 1975 sim- ilarly seeks answers to three fundamental questions. 1. Has the reservoir benthic faunal composition changed since the first year of plant operation? 2. Do the reservoir populations still exhibit expansive, log— phase growth? 3. Generally, how does reservoir benthic abundance compare with that of Lake Michigan? DESCRIPTION OF AREA The Ludington Pumped Storage Project is located 4 miles (6.4 km) south of Ludington Michigan on the eastern shore of Lake Michigan. The facilities include six Francis-type reversible pump-turbines each capable of a maximum 12,625 cfs (357.5 m3/s) discharge while generating elec- tricity and 11,139 cfs (315.4 m3/s) during the pumping mode (Comninellis, 1973). Water transfer between Lake Michigan and the reservoir occurs through six penstocks 1,300 feet (396 m) in length and 28.5 feet (8.7 m) in diameter at the top while tapering to 24 feet (7.3 m) at the lower end. The reservoir is 2.5 miles (4 km) long, averages .75 miles (1.2 km) in width and has a total surface area of 842 acres (3.4 km2) when full (Figure 1). The reservoir embankment is 108 feet (33 m) in height and has its inside perimeter sealed with asphalt. The reservoir bottom is composed of compacted clay with a 1,200 (365 m) by 800 (244 m) foot scour protection area consisting of limestone rocks in front of the intake structure. Maximum water depths range from 97 feet (29 m) in the south end while increasing to 112 feet (34 m) in the north. The power plant is protected laterally from potentially destructive wave action by two 1,750 feet (533 m) long and 45 feet (15.3 m) high jetties constructed from large limestone boulders rising to a height of 3 m above the lake level. An outer breakwall 1,700 feet (518 m) long and 45 feet (15.3 m) in height affords similar protection with 1,300 feet .moofiumum wowaaamm pom uHo>uommm couwoapsa m5» «0 wa> Hmflum< .H muowfim (396 m) clearance between the jetties and breakwall allowing uninhibited passage to the plant site. The area between the jetties was dredged uni— formly to a depth of 35 feet (10.7 m). LITERATURE REVIEW The colonization of new bodies of water has received considerable attention. Roll et a1., (1959), Kruglova (1959), Ozhegova (1962) and Sokolova (1963) studied the benthos of newly impounded reservoirs. These Russian basins are basically large fluviatile impoundments making direct comparison ill—advised. Several North American studies have focused on existing facilities but few have data from their inception. Burris (1954), Nursall (1952), Fillion (1967) and, more recently, Parterson and Fernando (1969, 1970) studied the benthic colonization of reservoirs soon after filling. These impoundments flooded terrestrial vegetation and a eutrophic-oligotrophic successional period, lasting more than a year, was attributed to the initially high organic content of the sediments. Brinkhurst (1974) dis- cussed the manner in which depth, temperature, food supply, predatory interaction, current and substrate shape benthic distribution and abun- dance in lakes. Liston, Tack and Duffy (1974) reported a vertically homothermous reservoir at Ludington where temperatures seasonally mimic those of ad— joining inshore Lake Michigan. The chemical parameters, similarly, are not significantly different than those of Lake Michigan, with high dis- solved oxygen concentration ranging from 10-12 ppm throughout the season (Liston, Tack and Brazo, 1976). The dependence of the benthic community upon autochthonous and allochthonous sources of organic material has been well documented (Deevey, 1941; Rawson, 1942; Jonasson, 1965). Historically, Lake Mich- igan phytoplankton has been dominated by diatoms, comprising an average of 94% of the total (Davis, 1966). In the Ludington Reservoir diatom populations follow closely those of Lake Michigan with respect to com- position and abundance (Liston, Tack and Duffy, 1974). Serchuk (1976) discovered fish mortality associated with both pumping and generating modes of the Ludington Pumped Storage turbines. Unpublished results (Koehler, 1975) revealed passage of larval fish and invertebrates into the Ludington Reservoir with unknown mortality. Gulvas (1976) outlined the colonization of fishes in the Ludington Reservoir. Although Species composition and abundance differ consider- ably from Lake Michigan collections, resident populations of sculpin, trout perch and carp seem to have become established. Virtually all Lake Michigan species periodically inhabit the reservoir. Food habits of several Lake Michigan fishes adjacent to the Ludington Plant were investigated (Armstrong, 1973; Brazo, 1973; Chiotti, 1973; Hauer, 1975; Kavetsky, 1975). Those species studied have not yet estab- lished significant reservoir populations; consequently, informative Ludington Reservoir food habit data have yet to be obtained. Several studies have been conducted upon Lake Michigan macro— benthos. Of direct application was a study conducted upon the inshore region of Lake Michigan in conjunction with the Ludington Pumped Storage Project (Olson, 1974). Similar impact studies have been attempted upon the Cook Nuclear Power Plant near Benton Harbor, Michigan (Mozley, 1974; Mozley and Garcia, 1972; Mozley and Winnell, 1975). Other investigations of Lake Michigan macro-benthos have concentrated primarily on the influ- ence of depth and substrate upon species abundance and composition (Eggleton, 1936; Cook and Powers, 1964; Powers and Robertson, 1965; Robertson and Alley, 1966; Howmiller, 1974; Stimpson et a1., 1975). METHODS AND MATERIALS Field and Laboratory Procedures A sampling scheme designed to reflect major changes in species abundance and composition was used for this study. The sampling period for each year began in April and subsided in October. A north—south sampling transect was implemented with six sampling stations distributed uniformly along the transect. The ponar dredge was utilized throughout this study and similarly by Olson (1974). Monthly collections, consisting of four replicate casts, were randomly made in the vicinity of stations one, four and six (Figure l). szley (1974) employed similar replication as increased sampling effort yielded a comparable estimate of the population mean. Hester—Dendy multiple plate samplers consisting of fourteen 20 cm square hardboard plates mounted vertically on an iron shaft, augmented the dredge information. On April 16, 1974 and April 7, 1975 three Hester-Dendy samplers were located at each of six stations along the north-south transect. One sampler was removed from each station in June, July and August. A total of eighteen samples was collected each year. Individual ponar and Hester-Dandy samples were returned to the Laboratory for processing. Each replicate was strained through a U.S. Standard #30 sieve, the organisms removed and preserved. The Chiron- omidae were preserved in 70% ethanol, and identified to genus using a Zeiss phase-contrast compound microscope and several taxonomic keys 10 (Roback, 1957; Bryce and Hobart, 1972; Mason, 1973). The Oligochaeta were preserved in 10% formalin, identified to genus using Hiltunen (1973) after they were cleared several days in Amman's lactophenol. Miscellan- eous organisms were preserved in 70% ethanol and identified to genus using Pennak (1953). Counts of each taxa were transformed to numbers per square meter for comparative purposes. The ponar dredge, with a total sampling sur- face area of 529 cm2, required a conversion factor of 18.9; the Hester- Dendy sampler with a 1.12 m2 surface area required a conversion factor of .89. Subsampling A subsampling procedure was implemented during the 1975 ponar dredge season due to large numbers of reservoir macrobenthos. Subsampling re- duced the processing time and allowed more time for identification and data analysis. Subsampling is used routinely in field investigations (Mozley, 1974; Lund, Kipling and Le Cren, 1958). When organisms are randomly dispersed between subsamples then the counts are distributed Poisson. (Elliott, 1971). A Chi—square procedure is applied to test the hypothesis of randomness and if agreement with the Poisson distribution is reached, a subsample may be used to represent the sample mean (Elliott, 1971). The 1975 Ludington macrobenthos were subsampled using a modified Wildco ponar dredge washing screen. The entire sample was spread uni- formly across the #30 mesh screen and sectioned equally into six sub- samples using a compartmented, fiberboard divider (Figure 2). The sub- samples were volumetrically reduced by passing water through the screen .mcHHmEmmnsm pow momam as HmpH>HQ pumonumnfim umuomauummEoo pom cmmuom 5mm3 umoom omHWHwoz .N muowfim l3 retaining organisms for easy removal. The Chi-square test was applied to the April 24, 1975 dredge sam— ples. The results (Table 1) indicated agreement with the Poisson dis— tribution for a variety of Oligochaeta and the midge Chironomus sp. Statistical Analysis As an aid in data analysis, a cross-tabulation procedure recorded the presence or absence of genera for a particular sampling date. Gen— era which regularly appeared in a year's sampling were selected for analysis of year and station effects. Those genera occuring infrequent- ly were combined within a single category of "Rare Species", and sub— jected to the identical statistical procedures. A logarithmic transformation of the original data was used through- out this study. Its use allows the variance to be independent of the mean while in most cases insuring normality of error terms and homogeneity of variances. Transformed data were analyzed by the Analysis of Variance technique (Sokal and Rohlf, 1969). Bartlett's test for homoscedasticity preceded use of the Analysis of Variance (Steele and Torrie, 1960). When the assumptions of the Analysis of Variance were fulfilled, genera were compared month by month between sampling stations and years. The Student—Neuman-Keuls procedure was employed for post-analysis contrasts of means (Steele and Torrie, 1960). Scheffe's procedure, although less powerful, was used for mean comparisons when Bartlett's test indicated heterogenous variance (Gill, 1972). Table 1. Counts of Five 14 Taxa of Six Replicate Subsamples. Species 1 2 3 4 Chi-square Tubifex 8p. 8 5 5 7 2.45 Imm. With Hair Setae 7 10 15 18 10.81 Limnodrilus sp. 6 9 4 3 8.68 Imm. Without Hair Setae 5 11 10 6 7.47 Chironomus sp. 4 6 8 13 6.33 Data exhibit randomness if Chi-square is less than 11.07 (p < 0.05) RESULTS AND DISCUSSION Ponar Dredge Samples - Major Groups The Oligochaeta and Chironomidae were the most abundant taxa in the 1974 and 1975 ponar dredge samples. Occasional Hydracarina, Amp- hipoda, Isopoda, Ostracoda and Gastropoda were collected. Oligochaeta The April 1974 Oligohcaeta standing crop was 2,784 individuals/m2 (Table 2). A decrease in abundance occurred in May with a modest in- crease sustained in June and August. Highest densities were in October (6,536/m2) but a further reduction occurred in November. A decrease in abundance in May 1975 samples from a seasonal high in April of 19,121/m2 persisted through the remainder of the 1975 sampling season (Table 3). The Oligochaeta abundance in 1975 was significantly greater than the 1974 density (p< 0.05). The population growth evident in 1974 fur- ther accelerated in 1975. Olson (1974, 1975) found a maximum Olig- ochaeta population of 800/m2. Results from the Ludington Reservoir show Oligochaeta standing crop has increased in each year of study. The Ludington Reservoir Oligochaeta were in greater densities than similar studies of reservoirs. Nursall (1952) found Oligochaeta in densities of 120/m2 while Fillion (1967) had a maximum of 719/m2. How— ever, Laurel Creek Reservoir sustained Oligochaeta in numbers approx- imating those of the Ludington Reservoir (7,000 - 12,500/m2). Lake Michigan studies (Eggleton, 1936, 1937; Mozley and Garcia, 1972; Robert— son and Alley, 1966; Olson, 1974) recorded lower Oligochaeta populations 15 16 mm m N o o o mpoaouummu o o o o m m muoomuumo o m N o o o «venomH S 2 3 m m m «confines. HH 0 m N m cm mowumomuuzm qu.H cow Hod mw<.H Oma mum ompwaooouanu amo.~ omm.o mmm mNH.a new «wa.~ mummeuowSHo H\HH H\oa m\w oN\o mm\m oH\¢ «naa :ome .uHo>umme aouwafiusn onu Scum moaaamm owpoun umaom qnma ca museum oHEooome scum: mo Na\uonasz and: %H:usoz .N manna l7 0 mm on o o o ovommomamm ma on o o o o muomouummu o o o o o o mpoomuumo o m o o o o muonomH mm mN o m m as meoaHnaa< o m o o o o mafiumomuumm aqm mmm mmm one moo.a wwo.H mmeaaoaouueu mam.s ma¢.m mem.s Asq.e Hmm.e HNH.OH mummnuomaso qH\oH oa\m «\w m\~ m~\m qm\¢ :oxme muma Eoum moamamm owooun umoom mnma CH mnsouu ofiaoaoxma scumz Mo N .Heo>uommm couwaavsg map E\uona:z ammz hasuooz .m canny 18 (400-2500/m2). However, Powers and Robertson (1965), Cook and Powers (1964) and Mozley and Winnell (1975) have shown similar Oligochaeta abun— dance ranging from 5,000-10,000/m2 in productive areas of Lake Michigan. As primary production and water chemistry are similar between Lake Michigan and the Ludington Reservoir (Liston, Tack and Duffy, 1974), other factors may account for the apparent differences in Oligochaeta abundance. Several explanations are possible. Predation pressure upon benthic macroinvertebrates may have differed between regions (Hauer, 1974; Kavetsky, 1975). Distinctions in species composition and abundance of fishes between the reservoir and Lake Michigan were apparent (Hauer, 1974; Gulvas, 1976). Oligochaeta, for the most part, reflect conditions prevalent within the sediments (Jonasson, 1975). The sandy sediments in Lake Michigan are disrupted frequently by wave action while the clay substrate in the reser- voir is more stable and thus may be a better habitat. Allochthonous organics may offer an alternate cause of higher stand- ing crop. Fish mortality from turbine operation added organic material to the Reservoir (Serchuk, 1976). The occurrence of the midge Stempeelina sp. in ponar dredge samples on June 26, 1974 and July 7, 1975 is especially noteworthy. Stempeelina sp. constructs transportable larval cases from available materials. Larvae collected with intact sand-grained cases offered direct evidence of the transportation of invertebrates from Lake Michigan. Organisms were pumped into the reservoir, but the mortality and biomass associated with their passage is unknown (Koehler, 1975). Organic enrichment of the reservoir is taking place but its extent and impact upon the Ludington Reservoir benthic community is unclear. It is assumed Lake Michigan receives organic inputs in a similar fashion. 19 However, the size of the respective basin coupled with the erosional conditions outlined, may not permit Oligochaeta abundance to approach that of the Ludington Reservoir. Chironomidae Total Chironomidae fluctuated with apparent peaks occurring in the June and November sampling periods of 1974 (1,485/m2 and 1,148/m2 res- pectively) (Table 2). The high November 1974 abundance was maintained into the 1975 season with comparable values during April and May of 1975 (Table 3). The peaks demonstrated in the 1974 Chironomidae were not apparent in the 1975 collections. A decrease in abundance occurred in October 1975. Contrasts of total Chironomidae between years were not highly significant although the 1975 density was somewhat greater than 1974 (p < 0.13). Olson (1975) found a maximum Chironomidae standing crop of 450/m2 in August 1973. Comparison of data revealed an increase of Chironomidae density during the three years of Ludington Reservoir colonization. Paterson and Fernando (1969) found a Chironomidae population of 6,000 - 14,000/m2 a density higher than that reported from the Lud- ington Reservoir. However, the former study was conducted upon a reservoir covering terrestrial vegetation which supported its benthic abundance. Investigations by Nursall (1952) and Fillion (1967), also done where terrestrial vegetation had been flooded, indicated densities similar to the Ludington Reservoir once the organic material disappeared. The Ludington Reservoir Chironomidae show a standing crop comparable to that found in adjacent Lake Michigan ranging from 500 to 1,500/m2 20 (Olson, 1974; Mozley and Winnell, 1975). In other Lake Michigan studies lower densities of 200 to SOO/m2 were reported (Eggleton, 1936, 1937; Robertson and Alley, 1966; Mozley and Garcia, 1972; Cook and Powers, 1964). The work of Olson (1974, 1975) and the present study may indicate locally productive conditions. The high abundances may be a result of characteristically high inshore densities, local eutrophication or operational effects peculiar to the Ludington Pumped Storage Project. Jonasson (1975) indicated the Chironomidae are sensitive to those conditions near the sediment-water interface. Increased detrital mat- erial resulting from current patterns and fish and invertebrate mor- talities may have increased Chironomidae abundance. Less Abundant Groups The occurrences of Hydracarina, Amphipoda, ISOpOda, Ostracoda and Gastropoda in 1974 and 1975 samples were sporadic (Tables 2 and 3). Abundances in all groups were low with no significant increases from 1974 to 1975. The occurrences of these groups appear less frequent in 1975. This result may be misleading. The subsampling procedures initiated in 1975 may not adequately represent those taxa collected infrequently. Comparison with 1973 results have shown no increase in standing crop of the minor groups since initial colonization (Olson, 1974, 1975). Ponar Dredge Samples - Generic Composition Oligochaeta Limnodrilus sp. and Tubifex sp. comprised the majority of sexually mature individuals in both 1974 and 1975 (Figure 3). The Immature 21 .moaaamm owpoua Hmoom mmmfilqmma ago 5% Hm>umuoH mafiHaEmm comm pow coxma some ou mam mummnoowwao kuOH mo mwMuomoumm o>aumaoaaoo .m muswam 22 Ohm. «Qum— 500 .88 .034 32. «as... >22 :54 .80 .83 .034 335 was... >22 pm» 5833. 023 .on 505:3 9.22:5 \\ 6QO Sum .3505 (hwdroocfio mums—DZ 442.05. o\o 23 With Hair Setae grouping likely represented immature Tubifex sp. while the Immature Without Hair Setae corresponded to both immature Limnodrilus sp. and Potamothrix sp. The percentage of mature individuals exhibited seasonal periodicity. Limnodrilus sp. and Tubifex sp. each demonstrated a high proportion of mature specimens early in the season. Reproductive activity subsequently declined as the summer progressed. The immature groups correspondingly increased throughout the season. Although a reduction of midsummer Potamothrix sp. occurred, no reproductive maxima was ascertained with the few number of specimens taken. Hiltunen (1967) and Stimpson et a1. (1975) have shown similar re— productive seasonality for Limnodrilus sp. and Tubifex sp. in Lake Michigan. The contribution of Tubifex sp. to the total abundance was greater in the Ludington Reservoir than in the aforementioned studies. Olson (1974, 1975) recorded Peloscolex sp. as a major species. This study noted the absence of Peloscolex sp. and the increase of Potamo— thrix Sp. The decline may be a result of taxonomic confusion of Peloscolex sp. as this form was exceedingly scarce and difficult to discern. Generic distribution between sampling stations yielded few sig- nificant trends (Table 4). The data demonstrated high variation be- tween stations. The abundance of Limnodrilus sp. and both immature groups was significantly less at station 4 during August, September and October 1975 (p < 0.05). Overall, the sampling stations were not significantly different during most sampling intervals. The genera appeared to be distributed equally over the reservoir bottom with no apparent north- south preference. o mm o o o mm o o o mm o 02 o 2: mm o o Na mm 2m wmv o 98H N9: 9 m: o m: 3m 33 o Em C mm 3 Rm onN Ewe omfl m3 KEN 8mm mm Rm EN 22 32 mgm 3% Rmm mug 9ch moo S2 oom 8v 2:. :2 83 R3 c o R RN 2: 23 SH mm :2 we... omm Ra meww Nam 39.. 98 33 Saw o mmm R No: oom omen meN “NR 2% ohm 8mm 23 NR 8 EH mm mmmH 3mm c o o m: o omom w: o o NE 30 N2: 3:: 28 Em NR $3 «N3 mm o N: a a o s m as R as c a o o m: as a l m e a o a s c an a o o a o o o o o _ as can an as E a 2m 8: E a o a an :2 as 3 a H m: o 8 an E a we a: m: s o a E a: a 3 o H saw an R mm as o as as am e a a e: as as s a _ a: s: a 5 ea c E g z s o a a 3 No a m a z: :2 S as ma 5:3 a 333m 23. an x: 50222. seam to: Song; 8325:. .3 “2:82: 22$ .3: 5:5 33%.... .9. 5333 3.8% 232m aciemm .8383. 85:83 2: Es: 3.95m 385 Econ. 22 can 22 5 38:89.0 8 v “.85 N 5:25.22 :82 new 8.8 25 Several authors (Brinkhurst, 1974; Hiltunen, 1967; Milbrink, 1973) make use of the concept of "species assemblages" to characterize water quality. Their studies attach significance to the occurrence of partic- ular species. Peloscolex ferox was found to be a good indicator of oligo— trophic conditions. Ilyodrilus templetoni as well as Aulodrilus pluri— seta were associated with those habitats recovering from severe poll- ution (mesotrophic). Eutrophic waters were inhabited with members of Limnodrilus spp., Tubifex spp. and Potamothrix spp. The Ludington Reservoir may have undergone a shift from originally oligotrophic conditions to those of a eutrophic habitat. However, the lack of specific identification may hinder such interpretations. Second- 1y it is not known what selective advantage is afforded those species capable of inhabiting clay substrate areas. Chironomidae The Chironomidae collections of 1974 and 1975 showed progressive alterations in species composition (Figure 4). Commencing in April 1974, the composition was partitioned between Chironomus sp., Crypto— chironomus sp., Polypedilum sp., Procladius sp. and Rare Species. A population increase of Polypedilum sp. occurred in June, 1974. Chiron— 2233 Sp. became the most abundant genera in August 1974 and remained so through the conclusion of this study. Similar reservoir investigations (Nursall, 1952; Fillion, 1967; Paterson and Fernando, 1970) revealed the successional dominance of Chironomus sp. A numerical decrease of Chironomus sp. was correlated with the reduction of organic material. Sokolova (1963) noted the in- crease of Chironomus sp. as a previously reophilic fauna adapted to a 26 .moamamm owumua umoom mmmalqnma was ca Hm>umucH onHmsmm Sumo mom come some cu map omvfiaooouano Hmuoy mo owmuowouom wpaumaoaoo .q muswwm CHIRONOMIOAE 27 SSS“. ’l”’/’, . 'Ill; MonadiameSa 'sp. ' \ ..qa Proc/adq'u s o. 9000 mus sp.:~ *“n 1? olypedI/u ' sp.. ypfoa‘umno ;. C I + Rare VII; H I \ ‘Y Yvo AL V” - :1 1 :11. fA pecies " .. \i . \\. : ° \k. Y A V AA A IV V Y h? m \ \ \\\\\>\ I 4 IO. 0 Chiron amus s pf lOO .1 90 80« 96 TOTAL NUMBER 40m 20- IO« April May June July Aug. Sept. Oct. April May June July Aug. Sept. Oct. |975 l974 28 limnetic existence. Olson (1974, 1975) found a Chironomidae composition in the Ludington Reservoir similar to the present investigation before Chironomus sp. became dominant. Inshore Lake Michigan studies (Mozley and Garcia, 1972; Olson, 1974) have shown the proportion of Chironomus sp. in relation to other Chiron- omidae. Chironomus sp. comprised at most 50% of the total in the afore- mentioned studies. The Ludington Reservoir supported Chironomus sp. in proportions higher (70 - 90%) than that reported in other Lake Michigan studies. Chironomidae distribution differed significantly between sampling stations (Table 5). However, Chironomus sp. accounted for the majority of station effects. At Station 1 Chironomus sp. had significantly higher densities in August, October and November 1974 than one or both of Stations 4 and 6 (p < 0.05). In April, August and October 1975, Station 1 was again significantly greater than one or both of Stations 4 and 6. Remaining genera showed no station differences except for one example: Cryptochironomus sp. was in greater abundance at Station 6 than Station 1 during the November 1974 sampling date (p 0.05). Chironomus sp. reached greater densities in the southerly regions of the Ludington Reservoir. Currents and food availability, somewhat interrelated, may be the cause for the southern preference for Chironomus sp. Chironomus sp. is most often collected in lakes, ponds and in quiet river pools (Curry, 1961). Detritus and diatoms formed the principal food items (Monakov, 1972). The operating mode of the Ludington Pumped Storage Project pro— moted substantial currents in the north section of the reservoir (Station 29 o o o R o o 3 m o 3 S m: mm Q o o o o m o 3 o m o o o o o o o o o 2 m o o R R o o 3 R R2 mm o NV m2 R o mm mm o mm 3 m3 mm 3 o E X: R mm o o o R o o o o ma 0 R mm mm o 2 m: mm o o 3 o o o 9 mm o R m: R 3 o o o mm mm o o mm NS may 8 cu em 3 o oo o o R mm c o o R o NoNN o c o o o R o o o o 3 to o o o o o Rm R o o o o 22 o om R mom mm R R m2 NS 8 2 8 2. 3 o m: R o on R 03 R 3 mm «N 3: mm mm o o 3 mm mm 3 o m as 2 8 m2. c Q: EN 22 3 Nu my o 3 o 0 SR R o2 8m 8m 8m R 3 o o mm mom 3o ZNN 82 RE 8% 3% 38 mm m RN 2 «:2 23 Ex N: omR 33 :3 :2 RE 33 SR 33 mm 0—4 H H H v a cozflm 3283 2mm .3 «853882 .3 38285 a... 53:83.8 .3 35822835 .3 3528ch 328mm 225m 3:33 c3533. c2363 2: So: 3353 maven. taco; £2 can 32 E 82528ch co m 5mg N 5.85:2 :82 can 83 30 6). The prevailing west-southwest winds often developed turbulent wave conditions in the north while it remained relatively calm in the south- erly portion of the reservoir. Currents and wave action no doubt in- fluence the rate and location in which food items become available to the benthos. A settling of particles may have occurred in the southern portion of the Ludington Reservoir. Lacking precise information, Chironomus sp. zonation in the south section of the reservoir is likely related to relatively calm waters and ample food supply. The abundance experienced in the south (Station 1) was far greater than any reported account in Lake Michigan (Table 5). The relatively large sieve size (600 microns) precluded observation of reproductive activity and pOpulation dynamics of the Ludington Reservoir Chironomidae. Many early instars were presumably lost while processing (Cummins, 1975). Less Abundant Genera Minor genera taken during the 1974 and 1975 ponar dredge collections are enumerated (Table 6). No significant yearly trends appear visible. A decrease in rare organisms was evident in 1975 indicated in part by Hygrobates sp., Lebertia sp., Mideopsis sp. and the Amphipods Gammarus sp. and Pontoporeia sp. Again, the subsampling in 1975 may not have adequately represented those genera. Hester-Dendy Multiple Plate Samples Amphipoda (Gammarus sp.), Isopoda (Asellus sp.) and Gastropoda (Physa sp.) were the major organisms found colonizing the Hester-Dandy plate samplers. Chironomidae were frequently collected while the Oligxhaeta Hydracarina, Ostracoda (Candona sp.) and Ephemeroptera (Stenonema sp.), TABLE 6 Monthly Mean Numberlm2 or Taxa in 1974 and 1975 Ponar Dredge Samples lrom the Ludington Reservoir ' an 27.5 Species 4716‘ 5/23 6I26 8I5 Inn 1171 4724 5729 7I7 874 9/16 10I14 Tublflcldae Aulodrllus sp. --- 0 0 26 o 0 0 12 9 0 IMrllus sp. --- 0 16 0 0 0 36 0 0 0 0 Limnodrilus sp. --- 81 217 92 115 214 1287 874 no 812 251 186 Imm. Without Halr --- 61 96 238 2824 492 2557 1354 13m 1096 2748 2486 Setae Peloscolex sp. --- 0 3 0 66 2 53 0 0 0 35 0 Potamothrix sp. --- 0 0 12 154 7 1084 507 66 160 242 9 7.9.9191 sp. --- 84 319 57 252 197 2935 600 111 50 18 163 Imm. With Hair Setae --- 51 196 250 1111 1144 2167 2142 4125 2443 2673 17m Neldldae N_al_s sp. --- 0 7 32 0 0 0 0 0 M sp. --- 0 38 82 0 0 0 0 0 Chlronomldae Chironomus sp. 22 19 2 0 698 876 1367 734 633 756 7% 227 c lronomus sp. 85 55 36 12 46 1% 113 110 19 28 189 28 Parachlronomus sp. 9 2 0 7 0 0 0 ' 0 0 0 0 0 Po llum sp. 25 3 14m 9 17 0 0 22 76 19 0 0 Stlctochlronomus sp. 0 0 0 0 0 0 0 0 0 0 9 9 Cladotanflrsus sp. 0 0 0 0 0 0 0 0 9 0 0 0 Mlcggflra sp. 0 0 2 0 0 0 0 0 0 0 0 0 Stemlllna sp. 0 0 9 0 0 0 0 0 9 0 0 0 Tanflrsus sp. 0 0 2 3 0 0 0 0 0 0 0 0 Procladlus sp. 44 9 9 12 16 50 142 76 9 19 9 47 Potthastla sp. 0 5 0 0 2 6 0 2 0 o 0 _ 0 Monodlamesa sp. 44 57 17 24 22 110 66 46 0 9 38 38 Heterotrlssocladlus sp. 16 2 o 3 0 0 0 0 0 o 0 Papa 0 5 3 0 0 0 0 9 0 76 0 0 Hydracarlna Ml! sp. a 3 3 2 o o o o o 0 mm» sp. 12 6 o 8 2 0 Mld_e_opsls sp. 0 0 2 2 3 2 0 0 0 o Amphboda Gammarus sp. 2 0 5 9 11 12 19 0 9 0 19 I) m sp. 2 5 3 5 0 5 0 9 0 0 9 2 Isopoda ME sp. 0 0 0 2 3 0 0 0 0 0 9 o Ostracoda Candona sp. 8 9 0 0 0 0 0 0 0 0 0 o Gastropoda M $_ 0 o o 2 9 22 0 0 0 0 76 19 Pelecypoda Sphaerlum sp. 0 0 0 0 0 0 0 0 0 o 28 0 ‘ Improper preservation ol the April 16, 1974 Ollgochaeta samples prevented detailed taxonomlc determination. 32 to a lesser degree, contributed to overall abundance (Table 7). Gammarus sp. and Asellus sp. showed an increase in 1975 abundance over corresponding 1974 values (p< 0.05) (Figures 5 and 6). A decrease in Hydracarina abundance was detected from 1974 to 1975 (p < 0.05) while remaining taxa sustained their respective 1974 populations with no de- tectable increase in 1975 standing crop. Olson (1974, 1975) reported maximum Asellus sp. and EEZ§2.SP' den— sities of 14/m2 and 4/m2 respectively in 1973. This study found higher densities in 1974 and 1975. Asellus sp. grew to a maximum of 60/m2 in 1974 while it increased to l43/m2 in 1975. Phy§a_sp. similarly increas- ed from 17/m2 in 1973 to a maximum of 67/m2 in 1974 and 183/m2 in 1975. Gammarus sp. had greater standing crop in 1975 than recorded in 1973 (Olson, 1974, 1975) while 1973 and 1974 densities were similar. The Oligochaeta and Hydracarina decreased in 1974 and 1975 from sub— stantially higher 1973 densities. The Chironomidae and Ephemeroptera did not increase since the first year of operation. On two occasions Ostracoda (Candona sp.) were collected, a group not previously encount— ered in the Hester-Dendy samples. The Tubificidae and Naididae of the Oligochaeta were equally rep— resented in the Hester-Dendy collections (Table 8). Limnodrilus sp. and Tubifex sp. comprised the mature Tubificidae as did Naig sp., Paranais sp”,and Stylaria sp. the Naididae. Stylaria sp., the most abundant genera, reached densities of 23/m2 in July 1975. Occurrences of most genera were rare and numerically low. The Chironomids Parachironomus sp. and Conchapelopeia sp. contri- buted major portions to Chironomidae abundance (Table 9). On occasion, Chironomus sp., Cryptochironomus sp., and Polypedilum sp. gained in 33 o o o n.m m. m. muoumoumEonam N.ow w.NwH w.m o.~o a.aa ~.~ meoaooummu o o o a. m. o msoumuumo o.Hoq a.mam o.mmu o.oo a.Hq m.~ mnoaomH m.mqs m.we H.Hc m.w~ o.sH H.ma meoaaeaaa o m. m. o 0.05 N. «caumumueam o.o~ ~.mm H.o m.a o.HH m.wa omeaaosouano o a.a~ m.o o o.“ a. mummnuomaao Ha.w sa.a oa\o a\m oa\a ~H\e mnma qn¢H oome .uwo>pomom souwowpog onu Scum moaaamm muconluoumw: whoa pom «Boa a“ mucosa owaoaoxma HOHmz mo Na\uoma=z coax Ranucoz .n oHan 34 Figure 5. Seasonal Abundance of Gammarus sp. (Amphipoda) in the 1974 and 1975 Hester-Dendy Samples. Mean Number /m2 200- | 00-1 01 9 mo: 9? <3 0" 1 35 Gammarus sp. — |974 "" |975 I I I I I I l I I I I I I I I I I I I I I T j April May June July August September 36 Figure 6. Seasonal Abundance of Asellus sp. (Isopoda) in the 1974 and 1975 Hester-Dendy Samples. Mean Number / m2 400- 30m 200- I 00- or 9 N (N O O l I 6 l U" 1 37 Asellus sp. — l974 I” -- l975 / I I I I I l I I I I I T I l I I I I I I I I April May June July August September 38 o N.mN o o N. 0 .am mmmmmwmm o o o o a. o mmmmmmmmM o m.m o.m o a. 0 .am mamz mmeaeamz o m.H a. o m.a m. mmumm pawn Spas .aaH o o o o o m. .am.mmmwmmw o m. m.e o m.~ o mmumm Hams oneness .aaH o m. o.H o m.H 0 .dm maawuuoaawg mmeaoauanna :3 it 33 a3 3: DR whoa whoa mowooam .uwo>uomom aouwawuag any Baum moaaamm muconluoumom whoa use chad oH muomzoomaao mo NE\uonB=z new: Ranuaoz .m manna 39 o o o m. N. 0 .am mafivmaoouuoomm m. o o o o o .mm mafipmaoommwuuouuuom o o o o o N. .am mam0uoowuo w.mH m.qN o.H m. N.m N.o .aw mfimwaoamsoaoo m. o o o o 0 .am mamumwwams o w.q o o o m.m .mm aaafiuommaom m.N o m.q m.w w. m.w .mm unaccouwnomumm o N. o m. N. o .9... $383333 0 m.m o o N. 0 .am unaccouN500umxmo o.H ©.N o o N. 0 .am maaoaoufinu umpwaoaoufino HH\w qH\N ca\o a\m 0H\N NH\o mnma qnma moaomam .uwo>uomom couwafiuog any Baum moaaamm muaomluoumom mnma pom qnma ca ompfiaoooufino mo Na\uonsaz amoz manuaoz .m oHan 40 importance while the remaining genera were rarely encountered. Hygrobates sp., Mideopsis sp. and Lebertia sp. comprised the Hydra- carina genera sampled (Table 10). These genera, seldom found in 1975, suggested a reduction in numbers from 1973 and 1974 (Olson, 1974, 1975). 41 o o o N.N N. N. .am mammmmmmmm muouaouoaonmm N.®N N.NNN N.N o.No N.Ns N.N .am mmwmm muoaouummo o o o N. m. 0 .am mmmmmmm mpoomuumo o.Nos N.NNN o.NmN o.oo N.Ns m.N .am mmmmmma. mpoaomH m.NSN N.NN N.No N.NN o.sN N.NN .am mmmmmmmm. meoaNnaa< o o o o N.NN 0 .am mmmmmmmmm o m. N. o N.s N. .am.mmmmmmmm o o m. o N.em 0 .am mmumnomwmm maaumomuuhm NN\N sN\N oN\o a\m SN\N NN\S mnma «Nod mofiouam was .uHo>uomom aoumawuaa Baum moaaamm upcomluoumom mmaa pom «Nod a“ mxme mo Na\Honaaz amoz Ranuaoz .oH manna SUMMARY AND CONCLUSIONS The continued colonization of the Ludington Pumped Storage Reservoir by benthic macroinvertebrates was monitored during 1974 and 1975. Data was furnished monthly via quadruplicate ponar dredge samples taken from April to October while Hester-Dendy samples augmented the dredge information during the summer months. Combined information yield- ed significant (p < 0.05) increases in Oligochaeta, Chironomidae, Am- phipoda and Isopoda abundance during the present two year study. Hydra— carina appeared to decrease in 1975. Since filling in 1973 the densities of Oligochaeta, Chironomidae, Amphipoda, Isopoda and Gastropoda have significantly increased. The Oligochaeta revealed a generic composition similar to that re- ported by Olson (1974, 1975) except for the decline of Peloscolex sp. and the recent introduction of Potamothrix sp. in the present work. Chironomidae drastically changed in generic composition as Chiron- omus sp. dominated the collections in late 1974 and all of 1975. A higher standing cr0p in the south end of the reservoir was assumed to be in response to favorable conditions and a generous food supply. Generally, the Ludington Reservoir had greater benthic abundance than Lake Michigan. The differences in current and substrate likely favored a higher benthic standing crop within the reservoir. Indicator organisms and direct evidence of allochthanous inputs indicated organic enrichment of the Ludington Reservoir since filling in 1973. This en- richment will continue in the future. 42 43 Further studies are needed to quantitatively determine the extent of allochthonous organic loading. Also, water current information cou- pled with sedimentation studies would be of value in the interpretation of benthic distribution patterns. LITERATURE CITED Armstrong, J.W. 1973. Age, growth and food habits of the round white— fish, Prosopium cylindraceum (Pallas), in central Lake Michigan. M.S. Thesis. Mich. State Univ. 76 p. Brazo, D.C. 1973. Fecundity, food habits and certain allometric features of the yellow perch Perca flavescens (Mitchell) before operation of a pumped storage project on Lake Michigan. M.S. Thesis. Mich. State Univ. 75 p. Brinkhurst, R.O. 1974. The benthos of lakes. The Macmillan Press LTD. London. 190 p. Bryce, D., and A. Hobart. 1972. The biology and identification of the larvae of the Chironomidae (Diptera). Entomologist's Gazette. 23:175-217. Burris, W.E. 1954. The bottom fauna development of a newly constructed pond in central Oklahoma. Proc. Okla. Acad. Sci. 33:129-136. Chiotti, T.L. 1973. 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The quantity and composition of the bottom fauna of thirty-six Connecticut and New York lakes. Ecol. Monogr. 2:413-455. Eggleton, F.E. 1936. The deep-water fauna of Lake Michigan. Papers Mich. Acad. Sci., Arts and Letters, 21:599—612. 44 45 Eggleton, F.E. 1937. Productivity of the profundal benthic zone in Lake Michigan. Papers Mich. Acad. Sci., Arts and Letters, 22:593—611. Elliott, J.M. 1971. Some methods for the statistical analysis of samples of benthic macroinvertebrates. Freshwater Biol. Assoc., Scientific Publ. no. 25:144 p. Fillion, D.B. 1967. The abundance and distribution of benthic fauna of three mountain reservoirs on the Kananaskis River in Alberta. J. Appl. Ecol. 4:1—11. Gill, J.L. 1972. Current status of multiple comparisons of means in designed experiments. J. Dairy Sci. 56:973-977. Gulvas, J.A. 1976. An evaluation of the composition and abundance of fishes pumped into the Ludington pumped storage reservoir from 1972 to 1975. M.S. Thesis. Mich. State Univ. 107 p. 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Fish. Wildl. 1974 Ann. Rep. to Consumers Power Co., Vol II (Physical-chemical Aspects). 65 p. Liston, C.R., P.I. Tack and W. Duffy. 1974. A study of the effects of installing and operating a large pumped storage project on the shores of Lake Michigan near Ludington, Michigan. Mich. State Univ., Dep. Fish. and Wildl. 1973 Ann. Rep. to Consumers Power Co., Vol II (Limnological Research). 196 p. Lund, J.W.G., c. Kipling and E.D. Le Cren. 1958. The inverted micro—9 scope method of estimating algal numbers and the statistical bias of estimations by counting. Hydrobiologia. 11:143-170. Mason, W.T. 1973. An introduction to the identification of Chironomid larvae. U.S. Environmental Protection Agency. 90 p. Milbrink. G. 1973. On the use of indicator communities of Tubificidae and some Lumbriculidae in the assessment Of water pollution in Swedish lakes. Zoon. 1:125-139. Monakov, A.V. 1972. 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The benthic macroinvertebrate populations in a new pumped storage reservoir and the adjacent coastal areas of central Lake Michigan. M.S. Thesis. Mich. State Univ. 220 p. 47 Olson, G.R. 1975. Preliminary studies of the colonization by benthic invertebrates of a new pumped-storage hydroelectric reservoir. Papers Mich. Acad. Sci., Arts and Letters. 8:501—513. Ozhegova, V.E. 1962. (Factors relating to the hydrobiological char— acteristics of the Kairak-Kumsk reservoir during the first year of its existence.) Tr. Zonal. Sov. po Tipos. 1 Biol. Obzn. ryb. ispol. Vnut. Vod. Yuzhn. Zony SSSR: Nat. Lending Libr. Sci. Technol., Boston Spa, Yorkshire, England. 172-177. Paterson, C.C., and C.H. Fernando. 1969. The macroinvertebrate colonization of a small reservoir in eastern Canada. Int. Ver. Limnol. 17:126-136. . 1970. Benthic fauna colonization of a new reservoir with particular reference to the Chironomidae. J. Fish. Res. Bd. Can. 27:213~232. Pennak, R.W. 1953. Freshwater invertebrates of the United States. Ronald Press, New York. 759 p. Powers, C.F. and A. Robertson. 1965. Some quantitative aspects of the macrobenthos of Lake Michigan. Proc. 8th Conf. Great Lakes Res., Great Lakes Res. Div., Univ. Mich. 153-159. Rawson, D.S. 1942. A comparison of some large alpine lakes in western Canada. Ecology. 23:143-161. Roback, 8.5. 1957. The immature Tendipedids of the Philadelphia area. Acad. Nat. Sci. Phila. Mbnog. no. 9. 152 p. Robertson, A., and W.P. Alley. 1966. A comparative study of Lake Michigan macrobenthos. Limnol. Oceanog. 11:576-583 Roll, Y.V., Y.Y. Tseeb, K.K. Zerov, K.S. Vladimirova, A.I. Denisova, and G.A. Olivari. The Kakhovka reservoir in the first year of its existence. Trans. Of the 6th conf. of the biology of inland waters. Translated from Russian for N.S.F. by the Israel Prog. Scient. Trans. Jerusalem. 415-427. Serchuk, P.M. 1976. The effects of the Ludington pumped storage project on fish passage through pump-turbines and on fish behavncr patterns. Ph. D. Thesis. Mich. State Univ. 130 p. Sokal, R.E., and J.J. Rohlf. 1969. Biometry: the principles and prac- tice of statistics in biological research. W.H. Freeman and Co. San Francisco. 776 p. Sokolova, N.I. 1963. .(The benthic fauna of the Mozhaisk reservoir during the first year of its existence.) Uchin. i. Mozh. Vod. Gilro Biol. -Pod. Fak. M.G.U. Mosk. Univ.: 355-374. (In Russian: Transl. by Nat. Lending Libr. Sci. Technol., Boston Spa, Yorkshire, England.) 48 Steel, R.G.D., and J.H. Torrie. 1960. Principles and procedures of statistics. McGraw—Hill Book Co. New York. 481 p. Stimpson, K.S.. J.R. Brice, M.T. Barbour, and P. Howe. 1975. Dis— tribution and abundance of inshore Oligochaetes in Lake Michigan. Trans. Amer. Micros. Soc. 94:384-394. 49 Appendix. Records of numbers per m2 of major invertebrate groups taken with each ponar dredge and Hester-Dandy sample in the Ludington Reservoir during 1974 and 1975. .NHQUQE\@HOQ§§ OHM mafia: 50 o o o eNN woe o Nm o emN eNe.e e O Na o eeN Nee O me o emm NNN.N 0 mm o emu Noo.e 0 mm o Nee emm.e e o Nm o Nae mme.e o o o mam mmN.m 0 ea As meN emN.N o as o Nm can N o o o Non NNN o o o oem NNN amuse economemeu <2HNmmmmm .Nuouoa\muonaaa one mafia: .mvomomH n .03 53 o o Nm mm mm o on o o Nmo o o o o No Noe o o oN on an o ea o oN mmN on o on NNN ooN.N e o o o NmN oNo oN o oN oNN oeo.N o oN o an oeN o o o NNN moo.N N o oN o NmN eoN oN .onN oN o oN NoN oom.N Nomeo ooooomamao eszaoamowm «ooonmzo maoNzozoNNmo «emomoooNNo ozoNaooo eN\m\w mmumzom moommo mozoo mHo>NMmmm . Hauoa\muonaoo mum muHaD .muomomH u .omH 54 N o o o o mom.o o o o on NmN.e o o oN oN no oom.N oN .enN o o oN NoN oNN.m oN .onN o oN oN o NeN.mN o o om ooN mom.oN e o o oN ooN oNo.m o oN o o eoo.N o o o mmN.N NoN.m o o o omo.N eeo.N N o oN oN NNN.N mNa.e o o o mmo.N oNN mango «oooomameo eszeoomoso oooonoz< mooNzozoNNmo «amoeoooNNo ozoNaoam eN\N\oN mmoozMMmmm 56 . uOan\muonaaa Ohm muHaD N o NoN.N ooo.NN NNN NoN.N NNN.o o nmN.N NNo.NN o o ems oom.NN o moo.N omn.NN o oem NNN.NN o eon NNe.o e o NNN NeN.m o Neo.N Noo.e o eNe.N oeo.N o mNm.m omo.N N o ooo.N mNo.e «oooomeoao «szooomosm «ooonmzo mooNzozomNmo oamemoooNNo ozoNaoem mN\eN\e mmomzom moommo Nazca mNoomNmmm .Nuouoa\muonaaa one mafia: 57 o o o moN ooo o o NNN oem oom.oN o o o o Non moo.NN o o o Nom.N NNN.N o o o o eoo.o Q o o o Non Noo o o o o ooo o o o eNo.N Nmo.N o o o emN.N oNo.m N o o o NeN.m o o o o Non moN mmmao 4oooomeommmmm . Hanan—\muonaao mum mafia: 58 N o o NNN NNN oN o o o NNN eoe.o o o o o Noo omm.mN o o o o moN.oN o o o oem moN.e o o o mNN omm.e o o o o o eNN.N o o o one Nom.N o o o oem oom.o o o o NNN NNN.N N o o o oom.N oNN.m o o o moN.e eNo.NN Nmmao ooooomameo eszaoemosm eooonmzo mooNzozomNmo oamamoooNNo ozoNaoam mN\N\N mmNmzmmmmm 62 . Houoa\muonaaa mum moan: .muouaouoaosam u .nmm N N .eom m o o o oN o o m N N o N o m N .eom m N o o oN e e e m N o oN o m N .eom e N N on Nm o N o o o oe o o N mmmeo eooNomN eoooomemeo eszeoeNosm eooNNmozo meoNzozoNNmo «amemoooNNo ozoNeesm eNNNN\o mmNNzem wozmoimmammm mNosmmomm . Houoa\muanaaa ONO muHGD .muoomuumo u .umo ”muouaouoaonam u .nam 63 N o N on e o o o .Lam Na on o H wH o m .Lam mH mH o N o o q .umo mNH on o wH mm HN m .umo mH NoH cwH mm H ON N .nam o on HON NN m H H mmmBO MMmmm 64 HQUQB\MHO£§H~ 0km mUHflD .NVOUGHUMO fl .umO “muuumouoaonnm a .nmm N .... .11. .11. .... .... .11. o .... .... .... .... .... .... o .11. .11. .... .11. .11. .11. e cum M .Nom oo o o NN o o N o .eom me meN o mN o o N N .eom on on o N NN o N mmoeo eoooooN eoooomameo eszeoemon «ooonNze meoNzozomNmo eaoeooooNNo ozoNeeem eN\o\o mmNmzem wozmo-mmammm NNooammNm oNHQUQa\m.H0n—§Hfl mum mUHd—D 65 NqH N H 0 NH O o omH oH N me m o m mNN 0H 0 Ne q o e ANN ON 0 «NH o o m no 0 0 on 0 ma N o o o mH o o H mmmeo mmmmm 66 H0u¢n<¢k0£§fi 0H0 mufiGD N qu NmH c «0 «c wH c mNm NmN o o Om #0 m can we N «H Hm me e NeN N o mH mN mm m owe amN 0 HH wN o N mH mmN o q HN HN H mmmho MMmmm 67 Houoa\muana=a mum muHab N III. .III ill. .III III. .11! O .III .III III. III. .III _III m om: ONH O mmH N O O Nmo «O O OON NH O m ooq ON O OHH ON O N NN HHH O ON O O H mmmeo «OomOmH