Abstract
Juvenile Atlantic cod (Gadus morhua) were exposed to water-accommodated fractions (WAFs) of Arabian light crude oil in two concentrations for one, two or three weeks. The last group was exposed for three weeks followed by a two-week depuration period in clean water. Selected biomarkers (polycyclic aromatic hydrocarbon (PAH) metabolites in bile, ethoxyresorufin-O-deethylase (EROD) activity in gills, hepatic EROD activity, hepatic cytochrome P-450 1A (CYP1A) concentration and comet assay) were tested for differences between the exposed groups and the control group. PAH metabolite measurements indicate that the exposure was successful. Fish exposed to a WAF of crude oil had significant increases in biliary 1-OH-phenanthrene concentrations, EROD activities and CYP1A concentrations compared with control fish – but responses did not appear to be dose-dependent. Levels of CYP1A and EROD activity were highest in the lower exposure group than in the higher exposure group throughout the exposure period. This may have been due to higher amounts of inhibiting substances, or a threshold of maximum induction may have been surpassed by the highest concentration WAF. Differences between groups with regards to these biomarkers were erased after depuration. There was no significant difference between exposed and control fish with regards to 1-OH-pyrene concentrations in bile. Further, the degree of DNA damage was not higher in exposed fish than in control fish. However, there were increases in DNA damage from the levels before exposure was started to levels in exposed and control fish. Damage levels were not bettered after depuration, indicating that two weeks of depuration is not sufficient to mend oil induced DNA damage.