Seasonal and pollution-induced variations in biomarkers of transplanted mussels within the Beagle Channel

► GST and SOD activities have been studied for the first time in mussels from Ushuaia Bay. ► LPO levels were higher in areas receiving urban wastewaters. ► Biomarkers and heavy metals were seasonally affected, probably associated to reproductive cycle. ► Superoxide dismutase activity was induced by heavy metals. ► Catalase activity would be the best biomarker considering that it was seasonal independent. The occurrence of biomarker variations linked to environmental factors makes it difficult to distinguish the effect of pollution. In an attempt to evaluate spatial and seasonal effects of environmental parameters on biomarker responses, mussels Mytilus edulis chilensis coming from an aquaculture farm were transplanted to several points within Ushuaia Bay (Beagle Channel) for 6weeks in summer and winter. Activities of superoxide dismutase, catalase, glutathione-S-transferase and levels of lipid peroxidation were measured in gills and digestive gland. Cu, Zn, Fe, Cd and Pb concentrations were also assessed. Results indicated a significant effect of seasons on biological responses as well as in metal bioaccumulation showing the influence of natural factors such as dissolved oxygen, temperature and food availability. The interdependence of those environmental factors is important for the homeostasis of thermoconformers, especially regarding their oxidative metabolism and should also be taken into consideration to distinguish natural from pollution-induced variations.