Acute lethality and effects of sublethal cadmium exposure on ventilation frequency and cough rate of bluegill (Lepomis macrochirus).

Several experiments were designed to determine the effects of sublethal cadmium exposure on ventilation rate and cough response of bluegill. Populations of test fish were selected to represent extremes in history of heavy metal exposures. Exposure to cadmium concentrations less than 1% of the reported median lethal threshold value produced significant increases in both ventilation frequency and cough rate. Changes in cough rates were directly proportional to the cadmium concentration. Cough response is an accurate short-term measure of chronic cadmium toxicity. There was good correlation between cadmium concentrations producing significant increases in cough rates and known MATC values. Based on acute toxicity studies and on changes in ventilation and cough rates, bluegill collected from a metal-contaminated lake did not exhibit increased tolerance to the toxic effects of cadmium.