Joint effects of crude oil and heavy metals on the gill filament EROD activity of marbled rockfish Sebastiscus marmoratus

• Crude oil WAF at the regular ambient levels induced the fish gill EROD activity.
• Cd or Pb at the regular ambient levels didn't inhibit the fish gill EROD activity.
• The ambient levels of Cd or Pb didn't affect the EROD activity induced by the WAF.

The aim of this study was to characterize dose- and time-dependent responses of gill 7-ethoxyresorufin O-deethylase (EROD) activity from Juvenile marbled rockfish (Sebastiscus marmoratus) exposed to the water-accommodated fraction (WAF) of crude oil and heavy metal Cd(Ⅱ) or Pb(Ⅱ) alone or in mixture. Compared to the control group, gill filament EROD activity in S. marmoratus was significantly induced after exposure to the WAF from 80 to 320 μg/L for 5 days in dose response experiment and after exposure to 40 μg/L WAF for 6–10 days in time course experiment, respectively. In the other hand, gill filament EROD activity were not significantly affected compared to the control group or related WAF groups no matter in the dose response experiment or in the time course experiment of Cd(Ⅱ), Pb(Ⅱ) or its mixture with WAF. The results suggest the use of gill filament EROD activity as a biomarker of exposure to waterborne AhR agonists in marine ecosystems while simultaneously being exposed to environmental concentrations of Cd(Ⅱ) or Pb(Ⅱ).