Differential response of biomarkers in the native European flat oyster Ostrea edulis and the non-indigenous Pacific oyster Crassostrea gigas co-exposed to cadmium and copper

Marine pollution favours the invasion and spreading of non-indigenous species in their new habitats. Comparative advantages of introduced and potentially invasive bivalves over their native counterparts might be reflected in better ability to cope with chemical stressors. The objective of the present study was to investigate differences in the biochemical stress response to Cd and Cu between the flat oyster Ostrea edulis (Linnaeus, 1758), native to European coasts, and its non-indigenous congener, the Pacific oyster Crassostrea gigas (Thunberg, 1793), recently detected in the eastern Adriatic. Oysters were co-exposed in vivo to sub lethal concentrations of metals. The stress response of two oyster species was evaluated using biomarkers of neurotoxicity (acetylcholinesterase, AChE), detoxification (metallothioneins, MTs) and oxidative stress (glutathione S-transferase, GST; lipid peroxidation, LPO). Biomarkers related to oxidative stress response were the most informative and suggested comparably lower capability of the non-indigenous C. gigas for handling pro-oxidant conditions after Cu exposure. Overall, the species-specific biomarker alterations displayed by oysters exposed simultaneously to the same experimental conditions represent the first evidence of differences between these two bivalves in the ability to overcome the chemically induced stress. The present research highlights the need for monitoring of biochemical features that might determine the behaviour of oysters in newly colonised habitats under environmental challenges foreseen in the upcoming years.