FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

The tolerance of red-tail shrimp juveniles, Penaeus penicillatus, to heavy metal toxicity was examined by exposing the juveniles at various developmental stages to varying concentrations of mercury, copper, cadmium and zinc in 30～32 ppt seawater (pH 7.1～8.5) at 25～27℃. The static renewal method was used for daily water exchange. The results indicated that LC50-24 h of Hg, Cu, Cd and Zn was 0.14, 3.26, 3.40 and 4.25 mg/L, respectively. The order of the toxicity was Hg > Cu > Cd > Zn. LC50 of Hg, Cu, Cd and Zn at 48 h was 0.06, 2.20, 1.90 and 2.09 mg/L, respectively, and the order of toxicity was found to be Hg > Cd > Zn > Cu. The toxicity tolerance of shrimp juveniles to the heavy metals varied with developmental stages; the tolerance to copper and cadmium increased as the development proceeded, while that to mercury and zinc declined as the shrimp developed.