Effects of EDCs in a wild gudgeon population (Gobio gobio L.) in Luxembourg
Résumé
For many decades human activities have dispersed toxic chemical substances in the environment. Over the last years new xenobiotics such as endocrine disrupting chemicals (EDCs), antibiotics or nano-particles have appeared. In order to assess the health of river ecosystems in relation to this increasing pressure, twenty sites contaminated at different levels were sampled by electrofishing across the Luxembourg hydrographical network. The status of fish communities was characterized according to an index of biotic integrity (IBI). Furthermore, on six sites, population structure, reproductive parameters and biochemical assays were performed on gudgeon (Gobio gobio) as sentinel species. Stress factor responses were observed at different levels of biological organization: from molecule up to fish communities. At one site, male gudgeons exhibited high levels of plasmatic VTG. Histological examinations revealed high alterations of the gonads: feminization of the testes and high incidence of atresia in ovary. No significant difference in the level of plasmatic VTG was noticed between intersex and non-intersex fish. Conversely, the incidence of atresia seems to be linked with VTG synthesis in female gudgeons. Weight index of the liver also highlighted an exposure to EDCs. More surprisingly, no impairment of the gudgeon population was pointed out. This study provides interesting data concerning endocrine disruption and their higher-level effects of the biological organisation in a wild fish population inhabiting Luxembourg's rivers. Factors potentially leading to alterations of the reproductive tract and more generally to a reduced fertility seem to be diverse and varied, and not exclusively VTG-dependent. By using a multiparametric and multiscale approach, a better understanding of response mechanisms to pollution in fish may be achieved and help improving the ecological status of river ecosystems.