The histological and biochemical effects of cadmium exposure in the bluegill sunfish (Lepomis macrochirus).

Cadmium effects on the bluegill sunfish (Lepomis macrochirus) were assessed histologically and biochemically and the effects were compared with effects on the ecologically relevant parameters of growth and survival. Growth and survival were monitored and tissues were removed for histopathological assessment of toxicant effects in a 163-day chronic exposure. The biochemical effects of cadmium were determined in a 32-day subchronic exposure. Exposure of fish to cadmium in hard water (363 mg Cd/liter) caused significant reductions in growth at 3.9 and 12.7 mg Cd/liter. Mortality was significantly increased over controls at 12.7 mg Cd/liter. Histopathological lesions were observed in gill tissue from fish exposed to 3.9 and 12.7 mg Cd/liter at all times during the chronic exposure. No histopathological lesions were observed in any internal organ during this exposure. In a 32-day subchronic exposure, cadmium caused significant increases in serum acid phosphatase and N-acetyl-beta-d-glucosaminidase activities. Serum aspartate and alanine transaminase and lactate dehydrogenase activities were not increased by cadmium exposure. Liver lysosomal membranes were destabilized by cadmium exposure. This indicates an alteration in lysosome function. The utility of biochemical and histological procedures for estimating safe concentrations of environmental pollutants are discussed.