Effects of coal combustion wastes on survival, physiology, and performance of the benthic feeding fish (Erimyzon sucetta)

A series of experiments were conducted to examine the effects of ash on the common benthic feeding fish (Erimyzon sucetta). In the first two experiments, exposure to ash under conservative experimental conditions (filtered softwater and uncontaminated food) resulted in trace element accumulation, as well as a significant decrease in fish growth, total nonpolar lipid storage, and severe fin erosion. In addition, fish exposed to ash had reduced sprint velocity (30–104%) and critical swimming speed (50%) compared to controls. The results from my first two studies demonstrated that exposure to ash results in a variety of sublethal responses that could ultimately decrease fitness. However, I concluded that my experiments were only a conservative estimate of the ecological hazards of ash to this fish species. Under more ecologically realistic situations, resources are often less abundant and such restrictions may alter the responses of organisms to environmental contaminants. Thus, a third experiment was conducted to examine the effects of ash under altered resource conditions. Fish were fed one of three ration levels (1X, 2X, 4X) that was grazed directly from either clean sand or ash-contaminated sediments. Fish in the 1X-ash treatment exhibited higher mortality, lower proportional growth, and increased incidence of fin erosion compared to fish provided with higher rations. Finally, in a fourth experiment fish were exposed in semi-natural outdoor mesocosms to water, sediment, and benthic resources from an ash-contaminated site and a reference site. Benthic invertebrates isolated from the ash mesocosms had trace element burdens up to 1000 times higher than in weathered ash sediments alone. Accumulation of trace elements, as well as reductions in growth and survival, were more pronounced than in previous laboratory studies, suggesting that resource conditions may be important in mediating ash toxicity. Taken together, my studies suggest that ash discharge into aquatic systems is a more serious threat to the health of benthic fish than previously predicted based upon laboratory toxicity tests and that nutritional factors should be carefully considered in chronic bioassays in order to draw more ecologically realistic conclusions about contaminant effects.