Oxidative stress responses and biological indices in the giant clam Tridacna maxima and the reef fish Epinephelus merra from the French Polynesian Moorea Island

► Responses of oxidative stress biomarkers in Tridacna maxima and Epinephelus merra. ► Biomarkers responses comparison between animals from an impacted and a reference site. ► CAT and TBARs levels increase in response to oxidative stress in the impacted site. ► First use of T. maxima and E. merra as suitable sentinel species in Moorea. Responses of biological indices and oxidative stress biomarkers were studied in the giant clam Tridacna maxima and in the fish Epinephelus merra collected from two sites differing by their level of contamination in the French Polynesian Moorea island. Higher levels of catalase (CAT), glutathione-S-transferases (GST) and thiobarbituric acid reactive substances (TBARs) were observed in the hepatopancreas of T. maxima and in the liver of E. merra compared to muscle. CAT and TBARs levels were significantly higher in the hepatopancreas of clams collected from the impacted site (Vaiare) compared to the reference site (bay of Cook). The same pattern was observed for TBARs levels in the liver of E. merra. These results indicate that both organisms from the impacted site were exposed to contaminants leading to an oxidative stress and demonstrate, for the first time, the usefulness of T. maxima and E. merra as sentinel species for biomonitoring reef environments.