Potential of the European bullhead (Cottus sp.) to assess the effects of pollution using a set of biochemical biomarkers

Multi-biomarker approach is extensively used to characterize the effects of ecosystem contamination on fish health. In order to measure multi-biomarker responses in freshwater ecosystems, numerous wild fish species have been used. However, the geographical distribution of these extensively characterized fish species did not allow a large sampling for ecotoxicological application and justifies the research of novel sentinel species for biomonitoring. The aim of this study is to characterize the potential of the European bullhead (Cottus sp.) as sentinel fish species to assess the effects of pollution using a set of biochemical biomarkers. This fish is widespread throughout Europe, and it's sedentary fish that allows assessing local disturbances conversely to migratory or mobile fish species. The selected biomarkers included biotransformation enzyme (i.e 7-ethoxyresorufin-O-deethylase, EROD), oxidative stress (i.e glutathione peroxidase, GPx and lipoperoxidation, TBARS) and neurotoxic parameters (i.e acetylcholinesterase, AChE). To evaluate the potential of European bullhead for biomonitoring, laboratory and field experiments were conducted. Laboratory investigations were performed to characterize chemical-induced variations of biomarkers using reference chemical compounds. For this purpose, bullheads were exposed to beta-naphtoflavone (BNF), fenitrothion and copper in order to evaluate respectively EROD, AChE and GPx activities as well as TBARS data. BNF generated a rapid induction of liver EROD activity in bullhead. Fenitrothion had no effect on the AChE activities. In field, wild bullheads were sampled, in the North of France, between September and October 2008 at seven sites considered as benchmark by the Water Framework Directive, and five contaminated sites. The selected set of biomarkers was measured in fish from sites exhibiting various contamination levels to evaluate discriminant power of this tool and to characterize response profiles in a multicontamination context. The response profile of AChE allowed a good discrimination between reference area exhibiting low AChE levels and contaminated sites with high AChE levels.