INFLUENCE OF WATER COMPOSITION ON THE CHRONIC TOXICITY OF 3,4-DICHLOROANILINE TO DAPHNIA-MAGNA

The influence of the composition of two synthetic media on the sensitivity of Daphnia magna to 3,4-dichloroaniline (3,4-DCA) has been tested in parallel. The two media differed in their content of trace elements. Medium M6 had only one-tenth of the trace element content of medium M4. The two media yielded similar results. The NOECs for the reproduction of live neonates, the most sensitive indicator of toxicant stress, were 6 μg/l 3,4-DCA. The development of parthenogenetic eggs and embryos was affected by the toxicant at concentrations ≥12 μg/1. It may be concluded that the trace element content of medium M4 does not exert a stress on Daphnia, this having an influence on the toxicity of 3,4-DCA. The results are in line with earlier experiments by the author using similar experimental conditions. This reflects a good reproducibility of results of chronic toxicity tests in a synthetic medium. © 1990.