Biochemical and Genotoxic Responses of Adult Eel (Anguilla anguillaL.) to Resin Acids and Pulp Mill Effluent: Laboratory and Field Experiments

The potential of a secondary-treated bleached kraft pulp mill effluent (BKPME) and resin acids (RAs) to induce liver ethoxyresorufin-O-deethylase (EROD) activity and erythrocytic nuclear abnormalities (ENAs) in adultAnguilla anguillaL. was investigated in laboratory and field experiments. Hepatic health was assessed by measurement of liver alanine transaminase (ALT). One single intraperitoneal injection of abietic acid (AA) or dehydroabietic acid (DHAA), at the same molar dose (14.7 μmol/kg), was given and fish were examined 3 days later. Only AA induced a significant increase in EROD activity while both RAs significantly increased the frequency of ENAs. A 3-day dose–response experiment (concentration range up to 2.7 μM) was also carried out for the same two water-diluted RAs. Both RAs induced a dose-related significant increase in EROD activity, presenting the same NOAEL (between 0.03 and 0.1 μM), while liver ALT activity significantly decreased. Both RAs revealed a mutagenic potential, measured as induction of ENAs, displaying the same NOAEL (between 0.1 and 0.3 μM). A laboratory experiment with 3 days of BKPME exposure revealed NOAELs between 12.5 and 25% for EROD activity and between 6.25 and 12.5% for ENA frequency. An additional laboratory experiment with 50% BKPME demonstrated that the minimal time necessary to induce a significant increase in EROD activity in the eel was 6 h. In a field experiment, caged eels were exposed in the river, at different distances (left bank: site 1–50 m; right bank: site 2–100 m, site 3–600 m, site 4–2000 m) from the BKPME sewage outlet. Liver EROD activity significantly increased at 1 and 3 days of exposure, with the exception of site 2, whereas ENAs were induced after 3 days of exposure at site 3.