EFFECT OF COPPER AND CADMIUM ON 3 MALAYSIAN TROPICAL ESTUARINE INVERTEBRATE LARVAE

Three species of tropical estuarine invertebrates were exposed to copp er sulfate and cadmium chloride to investigate their potential as test specimens for sediment toxicity assays in the Southeast Asian regions . The larvae of the reef sea urchin (Diadema setosum), the oyster (Cra ssostrea iradalei), and the mud crab (Scylla seratta Forskall) were us ed in the 48-hr assays with copper and cadmium as reference toxicants. In addition the sea urchin were tested for end point measurements at different stages of the larval development and a 60-min sperm bioassay . The study revealed that the sea urchin first cleavage, which is an a ssay end point and which takes place about 1 hr after fertilization, w as the most sensitive stage for both toxicants, with copper being more toxic than cadmium. Sensitivity comparisons between the three inverte brate larvae revealed the mud crab zoea larvae to be most sensitive fo r cadmium with an LC(50) value of 0.078 mu g/ml, while the sea urchin was more sensitive for copper, with EC(50) values of 0.01 mu g/ml at t he first cleavage stage and 0.04 mu g/ml at the pluteus larva stage. A ll the invertebrates tested gave responses that made them suitable tes t organisms for metal bioassays in the tropical estuarine environment. (C) 1997 Academic Press.