Factors Affecting Aquatic Macroinvertebrates Below a Fly Ash Pond Discharge

The effluent stream of the Cardinal Plant coal fly ash pond in eastern Ohio was characterized by less diverse habitat and food resources and a less complex substratum compared with an adjoining stream unaffected by the effluent, and supported a less diverse macroinvertebrate fauna dominated by physicochemically tolerant, fine particle-consumers. A sampling site in the unaffected stream contained large numbers of shredders and generally exhibited greater macroinvertebrate abundance than two sites in the effluent. Variation in numbers and taxa of macroinvertebrates among the three sampling sites was statistically associated primarily with differences in current velocity, substrate heterogeneity, and leafy detritus abundance, with fly ash pond water quality of lesser significance despite the presence of potentially toxic constituents.