Toxicity of cadmium and copper on larval and juvenile stages of the estuarine crab Chasmagnathus granulata (Brachyura, Grapsidae)

The toxicity of cadmium and copper were assayed in the estuarine crab Chasm agnathus granulata. Acute assays were made on the first larvae stage, and b oth acute and chronic assays were made on juvenile crabs. The acute lethal toxicity of the assayed heavy metals was three orders of magnitude higher i n 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 juven iles, according to the nonphysiological feature of cadmium and its persiste nt accumulation in organisms. During these chronic assays, cadmium produced both a significant mortality and a clear retardation of molting, in accord ance with its inhibitory effect on the molting process as previously report ed. Copper only caused a molting acceleration during chronic assays, perhap s 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.