Biomarker Assessment of the Effects of Coal Strip-Mine Contamination on Channel Catfish

A suite of biomarkers was used to evaluate acute (1-day) to semichronic (3-month) heavy metal-induced toxicity in channel catfish,lctalurus punctatus,caged at an abandoned strip mine and a noncontaminated reference site. Assays performed include indicators of metabolic, hematological, osmoregulatory, and genotoxic stress. Two cage designs were used to evaluate the importance of exposure routes: one excluding contact with the sediments and the other allowing contact with water and sediments. Significant DNA strand breakage was observed in catfish exposed to both exposure regimens, but evidence of DNA repair was observed only in water-exposed catfish. Transient increases in hemoglobin,δ-aminolevulinic acid dehydratase, and hematocrit levels were observed at 1 monthʹs exposure for both exposure regimens, followed by a return to control levels for the duration of the study. Environmental conditions (i.e., weather-related changes in water quality) may have contributed to the variable plasma chloride and glucose levels observed in all catfish exposed to strip-mine wastes. The transient changes in biomarkers followed by a return to reference values represent an initial stress and an acclimation to normal levels.