Multi-generational effects of four selected environmental oestrogens on Daphnia magna

The objective of this study was to determine whether vertebrate-type oestrogens have ecotoxicological effects on a crustacean species. The effects of 17β-oestradiol (E2), diethylstilbestrol (DES), bisphenol A (BPA) and 4-nonylphenol (4-NP) on the freshwater invertebrate Daphnia magna were assessed over first and second generations. The acute EC50 48 h, based on immobilisation, for E2, DES, BPA and 4-NP were 2.87 mg/l, 1.55 mg/l, 7.75 mg/l and 0.13 mg/l, respectively. The impact of the test chemicals on moulting frequency was also assessed. The EC50 48 h, based on the inhibition of moult number for E2, DES and 4-NP were 2.04 mg/l, 1.87 mg/l and 0.14 mg/l, respectively. BPA was not observed to impact the moulting frequency of D. magna at concentrations tested. In a series of separate studies, the effects of the four selected test compounds on the survival, moulting frequency and reproduction of first and second generational D. magna were assessed over a period of 21 d. Exposure of D. magna to 4-NP decreased the number of offspring produced in both first and second generation testing. DES proved to have no significant (p less-than-or-equals, slant 0.05) inhibition of fecundity in first generation but when second generation daphnids were exposed to DES, a significant (p less-than-or-equals, slant 0.05) reduction in the number of offspring was recorded. When D. magna were exposed to E2 or BPA, no statistically significant (p less-than-or-equals, slant 0.05) inhibition in the number of moults or offspring produced was observed.