Novel approaches methodologies in ecotoxicology - Metabolism reveals multigenerational effects of pollutants on daphnids

The field of ecotoxicology is advancing with the use of new approaches methodologies (NAMs) to scrutinize the effects of pollutants on aquatic ecosystems. This study employs cutting-edge methods to assess the impact of mixtures of eight pollutants on Daphnia magna, a keystone species in freshwater ecosystems. The levels of toxicity were in the same order of magnitude for the eight stressors, while the mixture was significantly more toxic. For the present study, daphnids were exposed for five consecutive generations to seven non-lethal and environmentally relevant concentrations ranging from 1 ng/l to 1000 μg/l. During the first generation, only the higher concentrations affected the enzymatic activities of daphnids, while after the third generation the effects were milder. In the fifth generation all concentrations, even the lowest, caused an impact on daphnids, while the animals exposed to the 1000 μg/l did not survive. Additionally, a feeding assay on D2 daphnids revealed a dose-dependent effect caused by the higher concentrations 500 and 1000 μg/l. Besides the biochemical markers, a targeted LC-MS/MS approach on the fifth generation daphnids confirmed the results from the former revealing a significant dose-dependent pattern even at the lower concentrations 1-100 ng/l. Our findings underscore the importance of not only acute or one generation chronic exposure, but multigenerational chronic exposures to investigate how the stress is carried out to the next generations.