Transgenerational toxicity of flumequine over four generations of Daphnia magna

In this study, the effects of both continuous and alternate exposure to 2 mg L-1 of flumequine (FLU) on survival, growth and reproduction of Daphnia magna were evaluated over four generations. Mortality was the most evident effect, with an average mortality rate of 23±14 % across generations. Individuals destined to succumb were identifiable well in advance through their discolouration and lack of development, and limited or zero reproductive capacity. Inhibition of reproduction in surviving mothers varied across the four generations (14.3±17 %) without an apparent correlation with the duration of exposure over generations. Significant reproductive inhibition was observed in the generation that followed three non-exposed generations (the fourth generation), pointing to a transgenerational toxicity of FLU. In another experiment, in vitro exposure of 72 D. magna embryos to 2 mg L-1 FLU caused 14% mortality (versus 7% in the control). Among the 62 individuals that hatched alive, six showed birth defects and only one was able to survive the next few days. The other, apparently healthy newborns were randomly assigned to two groups and submitted to a reproduction test, either in the absence or in the presence of 2 mg L-1 FLU. A high mortality rate and/or strongly significantly inhibited reproduction were detected in both groups. As with previously run analogous tests with enrofloxacin, the multigenerational and embryonic tests showed a clear disruption to this crustacean population which would not be evidenced by the standard official acute and chronic tests. This indicates the necessity of taking a different and more comprehensive approach to the evaluation of substances having an inherent ability to interact with genetic material.