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00213 making them poor indicator organisms for evaluating water quality. Winner et al. (19801 11 71 J, following a study of heavy metal pollu- tion in lotic ecosystems, hypothesize that heavi- ly polluted habitats are dominated by chirono- mids, moderately pOlluted habitats by chirono- mids and caddisflies, and minimally polluted or unpolluted habitats by caddisflies and mayflies. These trends are not clear from this study, as caddisflies and mayflies are found in areas of ap- parently severe heavy metals pollution. Fish Fish are generally more sensItIve to toxic pollutants than are invertebrates because of a longer and more complex life cycle. They require a more stable habitat and, therefore, they are ex- cellent indicators of long-term water quality. Fish population and species composition changed considerably from upstream of the ma- jor sources of heavy metals pollution to down- stream of these SOurces. A large population of brown and brook trout of 180-mm average length was found at EF-l, reflecting good quality water. The small size may also indicate that the habitat may be limited by flows, and severe winters may result in winter-kill. Heavy metals pollution downstream may also be a barrier to fish movement and in- tense competition may result in smaller in- dividual fish. Colder water temperatures may also slow growth, and water temperatures are always lower in the headwaters of mountain streams than downstream. Roch and Maly (1979) 11301 concluded that cadmium toxicity to rainbow trout was less severe at colder temperatures. This may also be true with olher metals. Smaller fish populations, of predominantly brown trout. were found at stations below the Leadville Drain, suggesting that these fish were adversely affected by heavy metals. Brown trout may be more resistant to heavy metals pollution than are brook or rainbow trout, as reflected by their abundance relative to the total fish popula- tion, or are naturally more aggressive when establishing a territory. The absence of any fish below the California Gulch inflow indicates that water quality above the Lake Fork inflow is en- tirely unsuitable for fish habitation. At AR-7 the collection of brown trout and two species of suckers indicate that water quality improved to some degree downstream of the freshening in-. flows. The deeper river channel downstream. the substrate. and the generally warmer water temperatures make it a more suitable habitat for suckers. Analyses for heavy metal content in brown trout livers showed that fish taken from severely polluted areas contained considerably higher levels of copper and zinc, indicating bioaccumu- lation of these elements and chronically high ex- posure to these metals. BIBLIOGRAPHY [11 Adams, M. P., "Treatment and Control of In- dustrial Wastes," Water Pollut. AbslT. vol. 14. 1941. /21 American Public Health Association, Stand- ard Methods for the Examination of Water and Wastewater, 14th ed.. APHA, Wash- ington. D.C., 1975. 131 Anderson. J. B.. and W. T. Mason. "A Com- parison of Benthic Macroinvertebrates Col- lected by Dredge and Basket Sampler," J. Water Pol/ut. Control Fed., vol. 40, pp. 252-259, 1968. 141 Armitage, K. B., "Ecology of Riffle Insects of the Firehole River. Wyoming," Ecology, vol. 3D, pp. 571-580, 1958. 15\ Arthur. J. W.. and W. B. Horning, "The Use of Artificial Substrates in Pollution Surveys," Am. Midi. Nat., vol. 82, No. I, pp. 83-89, 1969. (61 Beak, T. W., T. C. Griffing. and A. G. Appleby, "Use of Artificial Substrate Samplers to Assess Water Pollution." In: Biological Methods for the Assessment of Water Quality, J. Cairns and K. L. Dickson, editors, ASTM Spec. Tech. Publ. 528, pp. 227-241, 1973. (71 Becker, C. D., and T. L. Thatcher. Toxicity of Powerplant Chemicals to Aquatic Life, U.S. Atomic Energy Commission. UC-l', Wash- ington, D.C.. 1973. (81 Benke, A.C.. and J. 8. Wallace, "Trophic Basis of Production Among Net-Spinning Caddisflies in a Southern Appalachian Stream," Ecology, vol. 61. No.1. pp. 108-118. 1980. 39