Acute and Chronic Toxicity of Carbamazepine on the Release of Chitobiase, Molting, and Reproduction in Daphnia similis

As one of the most frequently detected pharmaceutical compounds in aquatic environments, carbamazepine (CBZ) has recently been shown to cause acute and chronic toxicity in a variety of non-target aquatic organisms. However, little is known about the ecotoxicological effects it has on the molting and reproduction of crustaceans. The aim of the present work was to evaluate the acute and chronic toxic responses to CBZ in the crustaceanDaphnia similis. After acute exposure (4 days), CBZ did not cause lethal toxicity at the tested concentrations. However, CBZ did inhibit the molting and release of chitobiase at concentrations higher than 6.25 μg/L, with 96 h EC50(median effective concentration) values of 864.38 and 306.17 μg/L, respectively. The results of chronic exposure showed that the mean number of molts, size of the first brood, mean number of offspring per brood, mean number of broods per female, and total offspring per female decreased significantly with increasing CBZ concentrations. Significant effects of CBZ on the molting or fecundity inD. similiswere observed even at concentrations as low as 0.03 μg/L. In conclusion, CBZ can cause inhibition of molting, delayed reproduction, and reduced fecundity inD. similis. CBZ toxicity toD. similisdepends on the timing and duration of the exposure. Moreover, our results indicated that CBZ would act as an endocrine disrupter inD. similis, as with vertebrates (e.g., fish).Keywords:carbamazepine;molting;Daphnia similis;chitobiase;chronic toxicity;reproduction