Evaluation of the relative sensitivities of 7-D Daphnia magna and Ceriodaphnia dubia toxicity tests for cadmium and sodium pentachlorophenate

Abstract A comparison of the results of 7-d Daphnia magna and Ceriodaphnia dubia toxicity tests indicated that the two species were equally sensitive to sodium pentachlorophenate (PCP) but that C. dubia was more sensitive to cadmium. The most sensitive chronic endpoint varied with species and test chemical. The most sensitive index of cadmium stress in D. magna was body length of primiparous females, whereas in C. dubia it was total young produced per female. For both D. magna and C. dubia, reproductive indices were more sensitive indicators of PCP stress than was survival. The results of this study, along with data from the literature, suggest that C. dubia is as, or more, sensitive to inorganic and organic chemicals than is D. magna, and that, if the indices of toxicity are carefully chosen, 7-d tests may provide estimates of no-effect concentrations that are as low as those generated in tests of longer duration.