Seasonal variation of biomarkers in Mytilus galloprovincialis sampled inside and outside Mar Piccolo of Taranto (Italy).

The aim of this work was to study spatial and temporal variation in biomarkers in autochthonous Mytilus galloprovincialis sampled inside and outside Mar Piccolo of Taranto, a typical polluted semi-enclosed basin of the Mediterranean Sea characterised by scarce hydrodynamism. Mar Piccolo of Taranto represents a site of Italian National Interest because of the high level of pollution. A battery of biomarkers (lysosomal destabilisation, catalase, metallothioneins, acetylcholinesterase, air survival) was applied to assess pollution-induced stress effects in authoctonous mussels. The responses were analysed comparatively in two different seasons, summer and winter, in order to assess possible changes in the pollutant-induced stress syndrome throughout the year. No significant difference inside and outside Mar Piccolo was observed for metallothioneins. By contrast, the dramatically decreased acetylcholinesterase values and strongly increased catalase activity in organisms taken from Mar Piccolo in winter indicate an increased risk of exposure to anticholinesterase compounds during this season. The results suggest the importance of temporal variability in biomarker responses throughout the year for monitoring possible seasonal changes in the pollutant-induced stress syndrome of organisms living in a certain environment and, in turn, more properly detecting changes in ecotoxicological risks.