Effect of diet quality on mussel biomarker responses to pollutants

Abstract

The effect of the quality of two microalgal species on select biological and biochemical responses usedas indicators of pollution were assessed. Mussels were conditioned for 6 weeks with the diatom Chaeto-ceros neogracile and the dinoflagellate Heterocapsa triquetra, chosen for being two clearly different typesof primary production quality that differ in both biometric and biochemical characteristics. After dietaryconditioning, the mussels were exposed to a polycyclic aromatic hydrocarbon, fluoranthene (FLU), for1 week followed by 1 week of depuration. Results showed higher FLU accumulation in mussels fed onC. neogracile compared to those fed on H. triquetra. Concomitantly, a greater impact of this toxicant wasobserved in the biomarker responses of mussels fed on C. neogracile. These mussels showed an increase inthe percentage of dead hemocytes, an activation of phagocytosis and ROS production of hemocytes afterexposure. Some enzymatic activities also increased upon FLU exposure (superoxide dismutase −SOD-, catalase −CAT-, and glutathione reductases −GR-) and after depuration (glutathione-s-transferase−GST-). Results suggest that FLU exposure as well as food quality influence biomarker responses, withhigher values of SOD, CAT and GR in non-exposed mussels fed on C. neogracile. In addition, upon exposureto the same FLU concentration, GR response varied according to dietary conditioning, suggesting that dietcould act as a confounding factor in biomarker responses to pollution. Consequently, trophic conditionsshould be considered in marine pollution monitoring programs for a better interpretation of biomarker responses.