Comparison of the susceptibility of daphnids and fish to benzene derivatives

Abstract

A battery of acute toxicity tests with a variety of aquatic organisms may represent a valid approach for preliminary hazard assessment. As the difference in sensitivity among species can be very large, it is fundamental that the test organisms are properly selected. The paper compares the sensitivity of three aquatic species — Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas (fathead minnow) larvae — to acute effects of toxicants. The comparison is based on data for nine compounds; namely, benzene and eight monosubstituted benzenes (MBs) expected to span a sufficiently wide range of toxicity. The results of acute toxicity tests with Ceriodaphnia dubia and fish larvae showed that the two organisms have a very similar susceptibility towards the tested chemicals, with the major exception of aniline, which was more toxic to daphnids than to fish (the actual LC 50s differing by more than two orders of magnitude). Toxicity data for Daphnia magna, available from a previous study, show a trend similar to that observed with Ceriodaphnia dubia, but, at the same time, suggest that this species is equally or more sensitive than Ceriodaphnia dubia and fathead minnow.