Environmental contaminants and biochemical response in eel exposed to Po river water

Groups of eels (Anguilla anguilla) were exposed to Po river water under control conditions at "la Casella" Fluvial Hydrobiology Station for 30-day periods between November and May. At the end of the exposure period, fish were sacrificed and cytochrome P4501A was evaluated in liver microsomes using both catalytic (EROD) and semiquantitative immunodetection (ELISA) assays. At the same time, water samples were taken for chemical analyses of PCBs, PAHs and pesticides. Eel was chosen as bio-indicator on the bases of experiments on cytochrome P450 expression and activity under basal or induced conditions and in consideration of the ecological and economic relevance and ease of handling. Low levels of cytochrome P450 during Winter were followed by a step increase during Spring, associated with a substantial concentration increase of agrochemicals. A good correlation was found between measurements of cytochrome P4501A by EROD and ELISA in dose-effect experiments, however, ELISA showed a higher sensitivity. Immunochemical techniques may be used in addition to enzyme activity measurements both to detect lower levels of cytochrome P450 induction (where they proved more sensitive) and as quality control. These results suggest that measurement of cytochrome P4501A under controlled conditions, using eel as bio-indicator, can be a useful tool in monitoring Po river ecosystems.