Effect of nutritive status on Mytilus galloprovincialis pollution biomarkers: implications for large-scale monitoring programs

Abstract

Biomarkers have been extensively used in monitoring programs with the aim of assessing the biologicaleffects of pollutants on marine organisms and determining environmental status. Data obtained fromthese programs are sometimes difficult to interpret due to the large amount of natural variables affectingbiological processes, which could act as confounding factors on biomarker responses. The main aim ofthis work was to identify the effect of one of these variables, the food availability, and consequently,the mussel nutritive status, on biomarker responses. For that purpose, mussels (Mytilus galloprovincialis)were conditioned to three different food rations for 2 months in order to create three mussel nutritivestatuses and afterwards, each status was exposed to three nominal concentrations of fluoranthene (FLU)for 3 weeks. A battery of biomarkers was considered in this study to cover a wide range of organismresponses, both physiological (scope for growth – SFG) and biochemical (superoxide dismutase – SOD,catalase – CAT, glutathione reductase – GR, glutathione peroxidase – GPx, glutathione-S-transferase –GST and phenoloxidase – PO activities, and lipid membrane peroxidation – LPO). The results obtained,evidenced that most of the studied biomarkers (SFG, SOD, CAT, GPx, and PO) were strongly affected bymussel nutritive status, showing higher values at lower status, whereas the effect of toxicant was notalways evident, masked by the nutritive status effect. This paper demonstrates that toxicants are notthe only source of variability modulating pollution biomarkers, and confirms nutritive status as a majorfactor altering biochemical and physiological biomarkers.