Résumé :
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This report presents part of a larger study conducted on the Naugatuck River, Connecticut, August 1983. In addition to the studies described here, there is another report describing efforts to model the toxicity as BOD is modeled (DiToro and Hallden, 1985) and a site-specific single chemical criterion study (Carlson et al., 1986). The major purpose of this study described here was to compare the relationship between measured toxicity of water samples collected from the Naugatuck River and the health of the aquatic community at the same locations where samples studyes area, habitat changes made the determination of toxicity effects on the stream community more difficult. Periphyton, benthos and fish species all showed a trend of reduced species richness from headwaters to mouth. The Ceriodaphnia and fathead minnow toxicity data show a similar trend. The zooplankton taxa did not follow an upstream downstream pattern. An impoundment and the large difference in stream between N-1 and N-12 may account for part of the difference. The effluent dilution tests were not performed in a manner that they could be used to predict impact because they were to be used for a mass balance model of toxicity and the needs for that that purpose were different. When toxicity and species richness were converted to normalized percent values and compared at four levels of impairment, up to 85 % correct predictions were achieved. Significant correlations ( P
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