Summary
Understanding the sensitivity of Antarctic organisms to metal exposure is essential for developing Antarctic specific Environmental Guidelines to manage contamination risks. For the first time, acute effects of copper and cadmium were determined in three common coastal Antarctic copepod species: Paralabidocera antarctica, Oncaea curvata and Stephos longipes over a 7 d exposure period. Copper was more toxic than cadmium for all copepod species. Paralabidocera antarctica was the most sensitive species for both metals with 7 d LC50 values for copper and cadmium of 20 ?g/l and 237 ?g/l respectively. Sensitivities to copper were similar for both O. curvata (LC50 = 64 ?g/l) and S. longipes (LC50 = 56 ?g/l). Oncaea curvata was slightly more sensitive to cadmium exposure than S. longipes with LC50 values of 901 ?g/l and 1250 ?g/l respectively. The response time to metal contamination was delayed in these Antarctic copepods compared to temperate and tropical species. Direct comparison of 1 to 4 d LC50 values, widely used in toxicity tests with related species from lower latitudes, to 7 d LC50 values used in this study, showed that the Antarctic copepods were more sensitive to copper and of similar sensitivity to cadmium. The study highlights the need for ecotoxicology studies with more relevant longer exposure periods for polar species to derive site specific Environmental Guidelines for Antarctic biota. Copepods are recommended as sensitive indicators of contaminant impacts in acute exposure toxicity tests as part of Risk Assessment procedures and for Guideline derivation.