Some effects of heavy metals and polychlorinated biphenyls on the estuarine organisms Brachidontes recurvus (Mollusca) and Penaues setiferus (Crustacea).

The results of toxicity experiments have shown that the hooked mussel (Brachidontes recurvus) is significantly more tolerant to ionic mercury than post-larval white shrimp (Penaeus setiferus). The 96 hour LC50 value determined for the mussel (0.27 ppm) was found to be a full order of magnitude greater than that determined for the post larval shrimp. In addition, the size of the shrimp, within the range tested (7-35 mm), were not found to significantly alter the toxicity values of mercury to this species. It was also shown that 60 days pre-exposure to low levels of mercury (0.5 and 1.0 ppb) had no effect on the acute toxicity (96 hour LC50)to the shrimp.