Ecological risk assessment in a large river-reservoir: 2. Fish community

This paper summarizes the assessment of risks to fishes in the Clinch River Operable Unit due to contaminants released by the U.S. Department of Energy's activities on its Oak Ridge Reservation in Tennessee. This paper focuses on the most contaminated area, the Poplar Creek (PC) embayment. The assessment is of interest because of its use of flee distinct lines of evidence: fish community surveys, fish body burdens, toxicity tests of ambient waters, suborganismal bioindicators, and single chemical toxicity tests. None of these lines of evidence provided unambiguous evidence of a significant risk, but the surveys indicated that the fish community in PC was depauperate, polychlorinated biphenyl body burdens may have been at toxic levels in catfish, one of the three tests of ambient water showed clear toxicity, some of the indicators were indicative of toxic effects, and concentrations that have been toxic in the laboratory were detected periodically. Interpretation was further complicated by upstream contamination of both the Clinch River and PC. The risk characterization was performed by evaluating each line of evidence separately and then weighing the evidence using an ecoepidemiological approach.