RESUMO
The toxicity of cadmium and copper were assayed in the estuarine crab Chasmagnathus granulata. Acute assays were made on the first larvae stage, and both acute and chronic assays were made on juvenile crabs. The acute lethal toxicity of the assayed heavy metals was three orders of magnitude higher in larvae than in juveniles. Cadmium proved to be more toxic than copper in most cases; this difference was more evident in the chronic assays on juveniles, according to the nonphysiological feature of cadmium and its persistent accumulation in organisms. During these chronic assays, cadmium produced both a significant mortality and a clear retardation of molting, in accordance with its inhibitory effect on the molting process as previously reported. Copper only caused a molting acceleration during chronic assays, perhaps as a detoxifying mechanism. Heavy metal concentrations having effects in the chronic assays have been reported in some sectors of the estuary where the assayed species lives.