Hepatic enzymatic activities of the european eel Anguilla anguilla as a tool for biomonitoring freshwater streams: laboratory and field caging studies

Hepatic monooxygenase activity and conjugation enzyme activity were studied in young european eel (Anguilla anguilla). Laboratories studies were performed by treatment with beta -naphtoflavone ( beta -NF). Two sources of eels, wild and reared eels were compared during a time-course study. MO activities measured as 7-ethoxyresorufin O-deethylase (EROD) were induced by beta -NF, peak values were reached 2 and 4 days after treatment. The time-course induction of EROD activity was similar for wild and reared eels. In contrast, the conjugation reaction enzymes measured as glutathione-S-transferase (GST) didn't respond to this treatment. During field studies, EROD and GST activities were studied in wild and reared eels held in cages upstream and downstream of a PAH polluted area. Similar induction of EROD activity was observed in the polluted site after 14 days of caging. The period of caging was studied and EROD activities were significantly induced in wild eels caged in the polluted site after 7 and 14 days. GST activities were not affected by the caging in the polluted site. The results indicate the usefulness of EROD activity as a biomarker of PAH contamination in the model of wild eels caging in the field.