Accumulation of Polychlorinated Biphenyls and Their Effects on Antioxidant Enzyme Activities in Tissues of the Ark Shell (Anadara kagoshimensis)

Abstract

Polychlorinated biphenyls (PCBs) are widely-spread aquatic pollutants that are toxic to aquatic organisms. The response of the antioxidant system in tissues and organs of bivalves to environmental stress is a commonly accepted biomarker in ecophysiological research. This study aims to evaluate bioaccumulation of polychlorinated biphenyls (PCBs) in tissues and organs of the ark shell Anadara kagoshimensis as well as effects of various concentrations of PCB mixture Sovol on the antioxidant enzyme activities. Upon in vivo experiments, ark shells were exposed to Sovol mixture in concentrations 0.00264 mg/L, 0.264 mg/L and 2.64 mg/L. PCB accumulation in hepatopancreas was by 4.8 times higher compared to gills and mantle. Tetrachlorobiphenyls and pentachlorobiphenyls accumulated in tissues preferentially compared to other PCB congeners. The bioaccumulation factor for PCB in tissues depended on its environmental concentrations. Exposure to PCBs affected the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GP). Despite gills accumulated less PCBs compared to other organs and tissues, treatment of ark shells with Sovol concentrations 0.00264 mg/L and 0.264 mg/L resulted in losses of SOD and CAT activities and enhanced GP activity. The opposite changes in the antioxidant enzyme activities were detected following the exposure to the highest Sovol concentration (2.64 mg/L). In the mantle the activity of SOD and CAT decreased, despite in hepatopancreas CAT and SOD activities were stable for the most experimental groups. The pattern of changes in GP indicates its critical role in the antioxidant defense following the exposure to PCBs.