The effects of metal (Cr, Pb) and salinity on ATPase activities of freshwater fish Oreochromis niloticus

In this study, freshwater fish Oreochromis niloticus were exposed individually to salinity concentrations (0, 2 and 8 ppt) alone and salinity+metal (1 ?g/mL Cr and Pb) exposures for different periods (1, 7 and 14 days). The aim of this study was to investigate the effects of salinity on metal toxicity by measuring the activity of Na+/K+-ATPase in the gill and intestine of O. niloticus after the exposure duration.Results showed that enzyme activity varied depending upon salinity, tissue, metal and exposure duration. Na+/K+-ATPase activity changed in fish exposed to both metal and salinity in relation to exposure conditions and duration. In salinity alone group, the increasing trend in enzyme activity was observed, whereas there was declining trend in the metal+salt mixture group. There was no significant metal accumulation in salinity alone group, though there were increases in the metal+salt mixture group.