Oxidative stress and immunologic responses following a dietary exposure to PAHs in Mya arenaria

Results on immune parameters suggest that the PAHs may interfere with the maturation and/or differentiation processes of haemocytes. MDA results showed that lipid peroxidation did not occur following the exposure. The levels of CAT activity corresponded to weak antioxidant activity (no significant differences). Recovery was noted for all the immune endpoints at the end of the experiment.Results suggest that immune parameters are early biomarkers that can efficiently detect a physiological change during a short term exposure to low concentrations of PAHs. The in situ survey (in the natural environment) suggested that clams from the Pointe-au-Père site did not show any oxidative stress as well as the clams contaminated in mesocosm, probably due to the low concentrations of PAHs used for this study. MDA levels increased however in organisms from Metis Beach, a response probably related to domestic effluents or parasitism.Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous in the environment. They are produced by incomplete combustion of solid and liquid fuels. High molecular weight PAHs are predominantly adsorbed on soot and particulate matter before being transported in aquatic environment. According to environmental conditions, they may accumulate in sediments [1]. Bioavailability to marine organisms is a consequence of different mechanisms such as bioturbation, sediment resuspension and diffusion. Bivalve molluscs are suitable species to assess toxicity in the environment due to their sedentary nature, filter-feeding behavior and ability to bioaccumulate pollutants like PAHs [2-5].Exposure to PAHs can lead to toxic effects in Mytilus edulis [5-10], Mytilus galloprovincialis [11,12], Unio tumidus [13], Mya truncata [14] and Perna viridis [15,16]. At cellular and molecular levels, exposure to PAHs may also trigger responses of biomarkers. For instance PAHs increase the formation of Reactive Oxygen Species (ROS) and induce detoxification systems like antioxidant def