Effects of antioxidant enzymes and bioaccumulation in eels (Anguilla japonica) by acute exposure of waterborne cadmium

This study was conducted to evaluate the acute effects of waterborne cadmium exposure on bioaccumulation and antioxidant enzymes in eels (Anguilla japonica) and to determine the median lethal concentration (LC.sub.50). Fish were exposed to different cadmium concentrations (0, 0.15, 0.30, 0.61, 1.83, 3.08, 3.67, 4.29, and 5.51 mg L.sup.-1) for 96 h. The LC.sub.50 of A. japonica to cadmium was 3.61 mg L.sup.-1. Cadmium accumulation generally increased in tissues with increasing waterborne cadmium concentrations. At [greater than or equai to] 1.83 mg L.sup.-1 exposure, all tissues accumulated significant cadmium concentrations compared with the control group, in the order of kidney > liver > gill > spleen > muscle. Measurements of variation in actual cadmium concentrations showed that a reduction of the metal in experimental water was related to cadmium accumulation in tissues. As activity alteration of antioxidant enzymes for reactive oxygen species, superoxide dismutase and catalase activities increased at [greater than or equai to] 0.61 mg L.sup.-1 significantly, glutathione peroxidase and glutathione S-transferase activities were not significantly changed. The results of this study suggest that acute exposure to waterborne cadmium is potentially fatal to A. japonica due to the metal's major accumulation in various tissues and the effect of antioxidant enzyme activity. Keywords: Cadmium, Anguilla japonica, Acute toxicity, LC.sub.50, Bioaccumulation, Antioxidant enzyme