Effect of diet quality on mussel biomarker responses to pollutants

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.

The authors are grateful to the LEMAR-IUEM team for technical and sampling support during the experimental period, in particular to Christophe Lambert and Laure Frère for their help with hemolymph and biological sampling and to Claudie Quéré and Fiz da Costa for algae proximal analyses. The authors would also like to express their gratitude to Francisco Gómez from the IEO Center in Murcia and to the technical staff of the PAHs Group from the IEO Center in Vigo for proximal mussel composition and chemical analysis. The authors would like to express their gratitude to Aswani Volety and Nick Shaw for their assistance with the English version of the manuscript.

Peer reviewed