OVERDUE FINES: 25¢ perm per item RETURNING LIBRARY MATERIALS: Place in book return to remov charge from circulation recov- EFFECT OF A METAL PLATING PLANT EFFLUENT ON LEAF PROCESSING RATES IN A STREAM By Karen Clark A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Zoology 1980 ABSTRACT EFFECT OF A METAL PLATING PLANT EFFLUENT ON LEAF PROCESSING RATES IN A STREAM By Karen Clark The purpose of this study was to determine if previously documented negative impact of a metal plating plant on macroinvertebrate populations in the Red Cedar River in southern Michigan affected leaf processing rates. Five gram leaf packs were placed in stream and periodically sam- pled. Water samples were analyzed for chromium, copper, nickel, and zinc. Zinc content of leaf packs was determined and found to be greater in leaf packs below outfall, but not at levels which would have detrimental impact on macro- invertebrate populutions. Except for the particularly fast breakdown rate at a gravel control site, leaf breakdown rates were similar for matching habitat sites above and below outfall. Macroinvertebrate fauna was similar for matching habitat sites. Lack of negative impact of effluent on leaf processing rates was attributed to improved water quality and macroinvertebrate faunal composition. ACKNOWLEDGMENTS I wish to express my appreciation to the members of my committee, Dr. T. Wayne Porter (chair), Dr. Frank D'Itri, and Dr. Earl Werner, for their advice and support. I also wish to thank Dr. Charles Cress for statistical advice and Charles Annett for aid in analyzing samples on the atomic absorption spectrophotometer. I am also grateful to Dr. Ellis of the Crop and Soil Science Department for aid in leaf zinc content analysis and for use of equipment. ii TABLE OF CONTENTS List of Tables ..................................... iv List of Figures .................................... v Introduction ....................................... 1 Description of Study Area .......................... 2 Methods ............................................ 5 Results ............................................ 8 Discussion ......................................... _ 14 Summary ............................................ 18 Literature Cited ................................... 20 Appendix ........................................... 22- iii LIST OF TABLES Table 1. Zinc content of leaves (mg/kg) ................ 9 Table 2. Leaf pack biomass remaining in grams .......... 11 Table 3. Analysis of Variance - Leaf Pack Biomass ...... 13 Tables A1—6. Macroinvertebrates collected from triplicate leaf pack samples ................................. 25-32 iv Figure Figure Figure Figure (.0me LIST OF FIGURES Map of study area ............................. 4 Leaf pack biomass-Grand River Road and Control.22 Leaf pack biomass-Gregory Road and Control ..... 23 Leaf pack biomass-Nicholson Road and Control...24 INTRODUCTION Small temperate woodland streams are characteristically heterotrophic, with allochthonous input as the major source of energy (Nelson and Scott 1962, Hynes 1963, Egglishaw 1964, Minshall 1967, Fisher and Likens 1972,1973, Cummins 1974). A large portion of this input is leaves. Thus, processing of leaves is an important function of these streams. Per- turbations of this process may have major impact on stream function and quality. Decomposition of leaves is largely a biological process in which insects, which are sensitive to heavy metal pollu- tion, play a significant role by shredding of leaves (Cummins .1973, 1974, Petersen and Cummins 1974, Boling 23 El- 1975). Previous studies on the Red Cedar River, a warm-water stream in southern lower Michigan, have shown that effluent from ’the Utilex metal plating plant had a significant impact on invertebrates (Garton 1968, Harrington 1974, Sylvester 1978). Below outfall, there was a reduction in numbers and types of insects, crustacea, and mollusks, with an increase in tubificids. The purpose of this study was to determine if this biological degradation significantly reduced the rate of leaf processing. DESCRIPTION OF STUDY AREA The Red Cedar River is a warm-water stream originating at Cedar Lake, Livingston County, in south central Michigan. It flows northwesterly approximately 73 km (45 miles) before entering the Grand River in Lansing. It drains an area of approximately 1220 square kilometers (472 square miles). Section of the river studied is tree-lined and located in an agricultural and residential area. Sources of residen- tial and industrial contamination to the river are concen- trated in Fowlerville (population 2000). Two major sources of pollution in this section are Hoover Universal-Utilex Division metal plating plant, which manufactures decorative plated zinc die castings and is located in Fowlerville, and domestic sewage from Fowlerville sewage treatment plant. Metal plating process and cooling water effluent enters the river 0.3 km (0.2 mi) north of Grand River Road Road bridge. Fowlerville sewage treatment plant utilizes a lagoon system, discharging wastes twice a year in spring and fall. Sewage is discharged 1 km (0.65 mi) below Utilex plant discharge. Six sites were selected, three above outflow of plating plant effluent and three below. Sites were selected to ena- ble those above discharge to match, as closely as possible, habitats of those below discharge. Sites below discharge 3 were located as follows: 0.2 km (0.1 mi) below discharge near Grand River Road; 2.1 km (1.3 mi) below discharge at Gregory Road and 4.3 km (2.7 mi) below discharge at Nichol- son Road (Figure 1). Grand River Road site had a soft black muck substrate with slow flow. Gregory Road site had a silt and sand substrate with moderate flow. Nicholson Road site had a sandy bootom with macrOphytes and a shallow, fast flow. Matching habitat sites for Grand River and Gregory Road sites were located at end of Garden Lane Road, 0.3 km (0.2 mi) above Utilex discharge point. These sites closely matched their downstream counterparts at Grand River and Gregory Roads. No sandy bottom site could be found above Utilex plant discharge to match Nicholson Road site, thus a site which most closely matched it was selected. This site was located at the railroad bridge 0.1 mile above discharge. It had a gravel substrate, but like Nicholson Road site had macrophytes and shallow, fast flow. .mmu< anaum no no: .~ ounwwm : . ax c.~ all-lunnulnilll- two. couam cm> z «and .mvumu N 1 WI . .5. .38 a 38335 was. .832 2.86 . 11/] unmam xmfiwua um>og“\ m. . a :m T. a a a. m. o N m A _ y. a w. “d I m , w m D. D. u c. 14 m. m : a P X a _ w uw>wm umvmu to“ p METHODS The experimental unit was a leaf pack composed of sugar maple (Acer saccharum) leaves. Leaves were collectd from a single tree at autumnal abscission, air-dried and weighed to 5.0 grams. Leaves were then soaked for a few minutes in water until they could be manipulated without breakage. Leaves were fastened together with a Buttoneer (Dennison Corp.) utilizing plastic I-bars. Bundles of leaves were then placed against brick faces and attached with an elastic garter. Bricks were placed in stream so that attached leaf packs faced upstream into current. This arrangement simu- lates natural leaf packs which form against objects obstructing the current, such as rocks, branches, logs, etc. Leaf packs were placed in stream June 28, 1978, and the last packs were removed August 13, 1978. Leaf packs were sampled approximately every 125 degree-days. Degree-days are a measure of stream temperature multiplied by time. There were eight pick—ups and three replicates per pick-up per site. Replicate leaf packs are designated A,B, and C in tables. A total of 144 leaf packs were used (6 sites X 8 pick-ups X 3 replicates). 6 Sampling procedure was as follows. Bricks with attached leaf packs were lifted from the stream bed. Individual leaf packs were slid off of bricks into a small Zip-Loo (Dow Corp.) storage bag and transported to laboratory. Leaf packs were disassembled and organisms visible by eye were rimoved and preserved in alcohol for later identification. Drganisms were identified using keys in Ross (1944), Pennak (1953), and Hilsenhoff (1975). Leaves were gently rinsed in water to remove attached sedi- ments, air-dried, and then weighed. Three water samples were taken at each site in poly- ethylene pint bottles. Three samples were also taken from the effluent. To prevent precipitation, 1 ml of nitric acid was added to each sample bottle. Samples were analyzed for total zinc, copper, nickel, and chromium levels using atomic absorption spectrophotometry. Before analysis, samples.were pretreated with nitric acid to digest organic matter using a method suggested by D'Itri (pers. comm.). Each sample bottle was rinsed a few times with nitric acid to remove material which may have adhered to walls of sample bottle. Each sample was boiled with excess nitric acid, then diluted to original volume with distilled water. To determine if increased metal concentrations below the discharge point substantially increased metal contents of leaves, thereby possibly having a deleterious impact on insect populations through the food chain, leaf packs were analyzed for zinc content. Leaf packs from second, fourth, sixth, and eighth pick-ups were analyzed following a method 7 suggested by Ellis (pers. comm.). Duplicate 1 gm samples of ground leaf material were taken from each leaf pack, except that 0.5 gm samples were taken from leaf packs which had insufficient material remaining to form two 1 gm samples. Samples were ashed at 500°C. for 4 hr. Residue was dis- solved in 5 ml of 2 N hydrochloric acid and filtered into a 50 ml volumetric flask. Beakers were repeatedly rinsed with 0.1 N hydrochloric acid. Rinsings were filtered into flasks until volumes were near graduations, and flasks were then brought to volume with distilled water. Zinc content of samples was determined using an atomic absorption spec- trOphotometer. RESULTS Concentrations in river water of chromium, nickel, and copper were below detection limits of 0.1—0.2 ppm at all sites for all samples. Chromium concentration in effluent was 0.4 ppm in the first sample and undetectable in thefother samples. Copper concentrations in effluent samples were 2.0, 0.75, and 0.65 ppm. Concentrations of nickel in efflu- ent samples were 0.65, 0.2, and 0. 2 ppm. Zinc concentra- tions in river water were below detection limit of 0.01 ppm for many samples and were barely detectable at levels of 0.01- 0.02 ppm for the other samples. Zinc concentrations in efflu- ent samples were 1.1, 1.2, and 1.1 ppm. These results were similar to those obtained in a Michigan Department of Natural Resources survey conducted May 22-26, 1978. Range in values inreffluent for 24—hr composite samples were 0.28-0.47 ppm chromium, 0.81-1.2 ppm copper, 0.50-0.87 ppm nickel, and 0.8- 1.6 ppm zinc (Saalfeld 1979). I Although variable, zinc content of leaf packs tended to increase with time while in the stream (Table 1). At all sites, average zinc content of leaf packs was higher than control samples of leaves not placed in stream for the sixth and eighth pick—up samples. Zinc levels in terres— tial leaf litter have also been found to increase with time (Lawry 1978). Zinc content was significantly higher for 8 9 Table l. Zinc content of leaves (mg/kg) Garden Lane - Grand River Control . Leaf Pack Pick-up A B C 7/11 5 5 32 56 5 35 7/22 6 6 35 33 20 21 8/2 43 44 15 23 70 66 8/13 35 39 44 36 29 29 Garden Lane - Gregory Road Control Leaf Pack Pick-up A B C 7/11 11 6 8 9 11 22 7/22 8 7 .6 6 8 7 8/2 16 15 24 25 52 35 8/13 42 21 106 111 15 36 Railroad Bridge Leaf Pack Pick-up A B C 7/11 16 18 9 14 24 18 7/22 10 21 7 8 8 8 8/2 7 5 5 5 53 70 8/13 69 62 62 85 46 50 Grand River Avenue Leaf Pack Pick-up A . B C 7/11 14 13 27 33 31 28 7/22 9 13 10 12 15 23 8/2 . 43 54 42 32 35 58 8/13 85 63 54 63 100 87 Gregory_Road _ Leaf Pack Pick-up A B C 7/11 6 7 32 35 10 7 7/22 24 15 14 48 18 27 8/2 43 54 42 32 35 58 8/13 81 62 21 31 48 37 Nicholson Road Leaf Pack Pick-up A B C 7/11 6 14 34 7 7 14 7/22 18 15 33 33 24 31 8/2 39 43 48 58 108 112 8/13 23 23 13 24 58 44 10 leaf packs collected below Utilex discharge point than for leaf packs from above discharge (P).01, planned contrast single degree of freedom F test). However, these levels were still relatively low, were will within normal range, and unlikely to have been having an adverse impact on insect populations. Leaf breakdown rates were very similar for the site immediately below discharge and its matching habitat site above discharge.(Figure 2, Table 2). Macroinvertebrates collected in leaf packs were also similar for these two sites. Chironomids and oligochaetes were predominant, with a few caddisflies, mayflies, amphipods, and flatworms also present at both sites. Leaf breakdown rate for the site 2.1 km below Utilex plant discharge was variable and gen- erally slower than its matching habitat site above discharge (Figure 3, Table 2). Macroinvertebrate fauna was also similar at these two sites. Chironomids were most abundant and oligochaetes were also numerous. Oligochaetes were more abundant at the site above discharge than at the site below discharge. Numbers and types of other taxa were similar and typical of sand-silt substrates. Rate of leaf breakdown was considerably slower at the site 4.3 km below discharge than at its matching habitat site above discharge, which had a processing rate consid- erably faster than the other habitat sites (Figure 4, Table 2). This result is typical for a gravel habitat. Gravel habitats usually have the fastest leaf breakdown rates (Reice 1974). 11 Leaf pack biomass remaining in grams Table 2. Grand River Avenue Garden Lane-Grand River Control Leaf Pack Leaf Pack 27138376 C07828959 43232222 27126375 396429059 . .. C . .C. 33332322 59798325 A07942123 o 00 o c 0.0 43233322 24437942 C05522665 O I. C 0... .43333222 12653210 BOQJéq/osnvrnv 43323232 75632551 A09349483 ...... O 0 43332222 U 1727 3 .41122281 k/l/l/l/l “1577777888 P Garden Lane-Gregory Road Control Leaf Pack Leaf Pack GreggryfiRoad 01/413546 C85886602 ........ 0 33222222. 8338/4986 01.187842 B 00. o c o o 0 43322222 58082695 A94395731 I. c ..... 33322222 70845217 C66301613 o o. . o o o 0 33233232 [44588402 375428370 0 o o o o o o 0 33332223 83088921.. 76511567 A o o 9. o o o 0 33333222 U 1727 3 .41122281 k//////// C77777888 m Railroad Bridge Nicholson Road Leaf Pack Leaf Pack C 1.93 1.57 3.89 3.80 3.42 3.52 3.60 3.24 2.90 2.60 1.87 2.88 2.81 1.68 2.68 1.76 2.19 1.58 2.40 2.32 2.25 2.24 1.76 3.81 06 3.20 69 3.25 73 2.87 44 2.65 36 2 01 O 3 8 2 7 2 O 2 6 2 .83 3.80 3.89 2 7 6 4 2 .76 3.33 3.83 .32 3.52 3.26 A 3 3 3 3. 2 2 2 2 Pick-u 7/4 7/11 7/17 7/22 7/27 8/2 8/8 8/13 12 Although Nicholson Road and railroad bridge sites were closely matched with respect to current flow and presence of macrophytes, these two sites had different substrates, one sandy and the other gravel. This difference in sub- strate resulted in different macroinvertebrate fauna and leaf breakdown rates. Nicholson Road site had a greater number of caddisflies and oligochaetes than railroad bridge site. It also had a greater number of mayflies, especially Caenis E23: a genus which is adapted to a sprawling exist- ence on the surface of fine sediments (Merritt and Cummins 1978). Railroad bridge site had more elmid beetles. In the analysis of variance, site as a source of var- iation was found to be highly significant (P>501) (Table 3). This is to be expected, regardless of impact of discharge, since leaf processing rates vary in different habitats (Reice 1974). The five degrees of freedom for sites can be parti- tioned to analyze effect of discharge. A planned contrast, single degree of freedom F test comparing sites above dis- charge to sites below discharge found this comparison to be highly significant (P>n001), indicating that discharge may be slowing leaf processing rate. However, two degree of freedom F tests of variation within site groupings found variation within above discharge sites to be very highly significant, while variation in below discharge sites was not significant. The sum of squares for sites above effluent discharge point was over two-thirds of site sum of squares. This high degree of variation can be attributed to the par- ticularly fast breakdown rate at railroad bridge site. 13 Table 3. Analysis of Variance - Leaf Pack Biomass Source A (Week) B (Site) AB Error Total _s_§_ 36.45 6.06 3.88 5.62 52.01 g; 5.21 1.21 .111 .059 E 89.06 20.68 1.89 E .001 .001 DISCUSSION Effluent from Utilex metal plating plant does not appear to be having an appreciable effect on leaf proces- sing rates. The site nearest discharge, where one would expect the greatest impact on leaf breakdown rates, had a rate very similar to its matching habitat site above dis- charge. Although rates above effluent were significantly greater than rates below effluent, much of this difference can be attributed to the especially fast breakdown rate at the gravel railroad bridge site. This site, although the best available, was not a good control site, for its dif- ferent sustrate type and community structure affected break- down rates and complicated overall analysis of breakdown rates. Due to this complication, it would not be appro- priate to attribute the statistically significant difference in breakdown rates in above effluent sites versus below effluent sites to effects of effluent, especially since the difference was very small for the site closest to effluent and its control site. Previous studies have shown that effluent was having a negative impact on insect populations (Garton 1968, Har- rington 1974, Sylvester 1978). Since shredding of leaves by insects is important in leaf processing, the negative impact of effluent could result in slower leaf breakdown rates below effluent. One reason that effluent did not ' 14 15 have a demonstrable impact on leaf breakdown rates may be improvement in water quality from previous studies. In 1966, Garton (1968) found elevated metal concentrations as far as 10.3 miles (15.5 km) below discharge. In the present study, levels of c0pper, nickel and chromium were below detection limits at all locations. In a series of samples in summer 1966, effluent levels were 0.9-2.2 ppm copper, 1.4-9.5 ppm nickel, 0.85-4.3 ppm zinc and 0.17- 3.4 ppm total chromium (Garton 1968) compared to 0.7-2 ppm copper, 0.2-0.7 ppm nickel, 1.1-1.2 ppm zinc and a maximum of 0.4 ppm chromium in present study. In 1966, macroin- vertebrate fauna near discharge was almost entirely tubi- ficids, which occurred in very high numbers (Garton 1968). Macroinvertebrate fauna was mostly tubificids in large num- bers in June 1972 before new pollution control equipment became operational (Harrington 1974). By June 1973, one 'year after pollution control equipment went into Operation, there had been a considerable recovery of macroinvertebrate populations. Numbers of organisms other than tubificids increased while numbers of tubificids substantially decreased (Harrington 1974). In September 1976, no mayflies or cad- disflies were collected in a 30-minute qualitative sampling at Grand River Road near Utilex discharge point (Sylvester 1978)} _In contrast, in this Study mayflies and caddisflies were collected at Grand River Road site. Chironomids were numerous at this site, while in previous studies macroinver- tebrate fauna was mostly tubificids. Number and variety of organisms were very similar to matching habitat site above 16 discharge point, indicating discharge was not appreciably affecting faunal composition. Since insects were not as severely affected as previously, it is not surprising that little impact on leaf breakdown rates was observed. Metal concentrations in effluent, especially copper concentrations, were at levels which are detrimental to some macroinvertebrate populations. In a static bioassay, 96-hr TLm's (concentrations producing 50% mortality) for Gammurus s2. were 0.91, 8.1, 13.0 and 3.2 ppm for copper, zinc, nickel and chromium, respectively (Rehwoldt g£_al. 1973). Corresponding values for Chironomus s2. were 0.03, 18.2, 8.6 and 11.0 ppm. These are levels which are acutely toxic. Levels which are chronically toxic, by means such as reduced growth and reproduction, would be even lower. In an on-site continuous-flow bioassay conducted May 22-26, .1978 in a mobile laboratory, testwater containing Utilex plant effluent concentrations as low as 12 per cent produced total mortality of Daphnia magna (Saalfeld 1979). Thus, effluent is likely to be having negative impact on macro- invertebrates in the immediate area of outfall. However, dilution of effluent in river water produced levels below detection limits in areas studied. At these levels, a nega— tive impact could not be distinguished in parameters studied, i.§. leaf breakdown rates and faunal composition. Although effluent and river metal concentrations have substantially decreased from previous levels, sediments are still considerably contaminated. Sediment samples collected 17 in January, 1978 had the following levels, in mg/kg, of chromium, copper, nickel and zinc, respectively: 1,300, 1,700, 200 and 2,000 immediately below discharge, 530, 430, 290 and 500 100 yards below discharge, 1,700, 1,500, 580 and 250 at Gregory Road, and 630, 590, 340 and 360 at Nicholson Road (Sylvester 1978). Elevated levels at Gre— gory Road may be due to an increased amount of organic matter, which has greater metal adsorption than mineral matter. Gregory Road is located 0.65 mi. below the dis- charge point of Fowlerville sewage treatment plant. Levels in sediment samples above Utilex discharge point ranged from 5.8-25 mg/kg for chromium, 9.1-36 mg/kg for copper, 12-35 mg/kg for nickel and 50-200 mg/kg for zinc. Howevern metal concentrations in sediments below discharge point have substantially decreased from earlier levels of 5,150 mg/kg chromium, 4,450 mg/kg copper, and 2,050 mg/kg nickel in samples collected in September 1967 (Sylvester 1978). The 1978 levels were below threshold avoidance levels of 4,000-8,000 ppm zinc and 800-1,500 ppm chromium for the midge Chironomus tentans (Wentsel gt El- 1977). SUMMARY Metal concentrations in effluent were at levels which can detrimentally affect macroinvertebrate populations at immediate area of outfall. However, dilutions in river water reduced metal concentrations in water samples below 0.1-0.2 ppm at all sites. Zinc concentrations of leaves increased while leaf packs were in stream. Although increased adsorption of zinc occurred on leaf packs located below Utilex plant discharge, zinc content of leaves remained at levels which would not have been deleterious to macro- invertebrate populations. Leaf processing rates in Red Cedar River were not sub- stantially affected by effluent from the metal plating plant. Leaf breakdown rates and macroinvertebrate populations were similar for sites below outfall and matching habitat sites above outfall, except for the gravellcontrol site which had a particularly fast breakdown rate. Rate of leaf pro- cessing was significantly lower below outfall, but much of this statistical significance can be attributed to fast breakdown at the gravel control site above outfall. Lack of a demonstrable negative impact on leaf processing can be attributed to water quality improvement and concommi— tant improvement in macroinVertebrate community structure 18 .19 and numbers. Levels of heavy metals in effluent and in the river have considerably decreased during the past decade. Consequently, there has been an improvement in macroinvertebrate fauna, with a decrease in tubificids and an increase in number and variety of insects. 'Metal concentrations in effluent remain at levels which are detrimental to some invertebrate populations and are a cause for concern, but the river no longer has the severe biological degradation documented previously. LITERATURE CITED Boling, R.H., E.D. Goodman, J.A. VanSickle, J.D. Zimmer, K. W. Cummins, R. C. Petersen, and S. R. Reice. 1975. Toward a model of jdetritus_processing_in a woodland stream. Ecology 56: 141- 151. Cummins, K.W. 1973. Trophic relations of aquatic insects. Ann. Rev. Entomol. 18:183-206. Cummins, K.W. 1974. Structure and function of stream eco- .systems. BioScience 24:631-642. Egglishaw, H. J. 1964. The distributional relationship between the bottom; -fauna and plant detritus in streams. J. Anim. Ecol. 33: 463- 476. Fisher, S.G. and G.E. Likens. 1972. Stream ecosystem: organic energy budget. BioScience 22:33-35. Fisher, S.G. and G.E. Likens. 1973. Energy flow in Bear Brook, New Hampshire: an integrative approach to stream ecosystem metabolism. Ecol. Monogr. 43: 421- 439. Garton, R.R. 1968. Effect of metal plating wastes in the ecology of a warm-water stream. Ph.D. Dissertation, Mich. State Univ., E. Lansing. 83p. Harrington, H. F. 1974. The effects of heavy metalsfi on species composition in a warm-water stream. M. S. Thesis, Mich. State Univ. E. Lansing. 54p. Hilsenhoff, W.L. 1975. Aquatic insects of Wisconsin; with generic keys and notes on biology, ecology, and distri- bution. Wisconsin Dept. Natural Resources, Technical Bulletin No. 89. 52p. Hynes, H.B.N. 1963. Imported organic matter and secondary productivity in streams. Proc. XVI Int. Congr. 2001. 3:324-329. Lawry, J.D. 1978. Trace metal dynamics in decomposing” leaf litter in habitats variously influenced by coal strip mining. Can J. Bot. 56:953-962. 20 21 Merritt, R.W. and K.W. Cummins, eds. 1978. An Introduction to the Study of Aquatic Insects. Kendall/Hunt. Minshall, G.W. '1967. Role of allochthonous detritus in the trophic structure of a woodland springbrook commu- nity. Ecology 48:139-149. Nelson, D.J. and D.C. Scott. 1962. Role of detritus in the productivity of rock-outcropscommnnity innagpiedé- mont stream. Limnol. Oceanogr. 7:396-413. Pennak, R.W. 1953. Fresh-water Invertebrates of the United States. Ronald Press. Petersen, R.C. and K.W. Cummins. 1974. Leaf processing in a woodland stream. Freshwat. Biol. 4:343-368. Rehwoldt, R., L. Lasko, C. Shaw, and E. Wirhowski. 1973. The acute toxicity of some heavy metal ionsl toward benthic organisms. Bull. Environ. Contam. ToxicoL 10:291-294. Reice, S.R. 1974. Environmental patchiness and the break- down of leaf litter in a woodland stream. Ecology 55:1271-1282. . Ross, H.H. 1944. The caddisflies, or TrichOptera, of Illinois. Illinois Natural History Survey Bull. vol. 23. 326p. Saalfeld, G. 1979. Report of a toxicity evaluation and industrial wastewater survey_conducted at the Hoover Universal- Utilex Division (outfall 470003), Livingston County, Fowlerville Michi 1g an May 22-26,1978. Michigan Dept. Natural Resources, Point Source Studies Section Report. 14p. Sylvester, S. 1978. Water quality and biological investi- gation of the Red Cedar River in the vicinity of the Hoover Universal Die Cast Co. Fowlerville Michigan September 9,1976 and January 24 1978. Michigan Dept. Natural Resources, Water Quality Division Report. 21p. Wentsel, R.,A. McIntosh, W.P. McCafferty, G. Atchinson, and V. Anderson. 1977. Avoidance response of midge larvae (Chironomus tentans) to sediments containing_heavy metals. Hydrobiology 55: 171- 175. Weight (grams) 22 0 Grand River Road A Garden Lane Control 4N AA V'V'VV v .r—IV‘ ' 7/4; 7/11 7/17 7722 7/27 8/2 8/8 8/13 Pick-up Figure 2. Leaf pack biomass-Grand River Road and Control Weight (grams) 23 0 Gregory Road A Garden Lane Control ‘ €E_ 714 7/11 7/17 7/22 7/27 ' 8/2' 8/8 8/13 Pick-up Figure. 3. Leaf pack biomass-Gregory Road and Control w Weight(grams) 24 O Nicholson Road A Railroad Bridge Control 7/4 7/11 7/17 7/22 7/27 ' 8/2 8/8 Pick-up Figure 4. 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