Sublethal Copper Toxicity and Food Response in the Freshwater Crayfish Cambarus bartonii (Cambaridae, Decapoda, Crustacea)

Food response preceding and following exposure to Cu concentrations of 0.00, 0.02, and 0.2 mg/L was observed in male and female Cambarus bartonii from an uncontaminated, freshwater lake. The animals were tested in a Y-maze. Control animals demonstrated food localization, and the treated animals, either no localization or slight food avoidance. The latency for localization in the Cu-exposed males increased. Females revealed slight increases in latency. There were no significant differences between the low and the high Cu concentration groups in food detection or latency. However, there was an increase in mortality in the higher concentration group and significant difference in mortality among three copper concentrations (P<0.02). Females seem to recover from Cu-induced impairment slightly faster than males, suggesting a more efficient mechanism for detoxifying copper. Female mortality, however, remained equally high in the high Cu concentration group. The toxic effects of copper persist after removal of the toxicant and occur at concentrations much lower than reported lethal levels.