摘要：Anthropogenic activities, such as agriculture and industrial activities, are a main source of pollution contributing for the degradation of water quality and thus affecting the living organisms of aquatic systems. Copper is widely used at these practices being often released into the aquatic systems and may cause negative effects in its communities. This study proposes to determine the effects of copper in the antioxidant defence system of two size classes (big and small sizes) of Scrobicularia plana and Cerastoderma edule, two marine bivalve species with commercial interest. It was observed the behaviour activity of the organisms during the exposure to copper sulphate (CS) and was determined the enzymatic activities of glutathione-S-transferases (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) (both selenium-dependent (SeGPx) and total (tGPx)) in the muscle tissue (foot). Lipid peroxidation (LPO) was evaluated through thiobarbituric acid reactive substances (TBARS) measurement in the foot. Changes in the behaviour and enzymatic activity were observed. Lipid peroxidation was observed at C. edule and S. plana big and small size classes, respectively, according to TBARS levels. The foot showed to be a good tissue to be used in biochemical analysis to detect the presence of toxicants.
