Alterations on the Activities of Ion ATPases in the Gill and Muscle of Freshwater Mussel (Unio tigridis) Exposed to Copper

Abstract

Ion ATPases in the tissues of aquatic animals are sensitive to metal exposures. Mussels are filter-feeding animals and have a sedentary lifestyle that makes them good bio-indicator animals. Thus, the present study was carried out to investigate the effects of copper (0, 30, 90 µg/L) on the activities of Na-ATPase, Mg-ATPase, and Ca-ATPase in the gill and muscle of freshwater mussels (Unio tigridis) in different exposure durations (0, 7, 14, 21 days). Feeding of mussels during the experiments were done with the cultured unicellular algae (Cholorella vulgaris), serving them approximately 300,000 algae/ml. At the end of 21 days of exposure period, no mussel mortality was recorded. Total protein concentrations in the gill and muscle did not change significantly (P>0.05) in any exposure groups. Likewise, control ATPase activities did not alter significantly during different exposure periods. However, ATPase activities in the gill and muscle of mussels altered significantly (P<0.05) following exposure to copper, especially at the higher concentration. Although there were significant increases and decreases in the activity of Mg-ATPase in both tissues, Na-ATPase and Ca-ATPase activities did not fluctuate as there were only significant decreases at the higher exposure concentration. The present data demonstrated that copper at environmentally realistic concentrations was able to alter the activities of ion ATPases in the gill and muscle of mussels and emphasized osmoregulatory stress which mussels might face in waters contaminated with copper.