Investigation of osmoregulation system of freshwater fish oreochromis niloticus exposed to Hg in differing salinities

In this study, freshwater fish Oreochromis niloticus were exposed to Hg2+ in differing salinities (0, 1, 10ppt) for acute (0,3 μM Hg2+, 3 days) and chronic (0,03 μM Hg2+, 30 days) exposure protocols. Following the exposures the activity of Na+/K+-ATPase, Mg2+-ATPase and Ca2+-ATPase in the gill and Ca2+-ATPase muscle of O. niloticus were measured. There were some significant alterations in ATPase activities in gill and muscle tissues of fish exposed to metals as single or combination with salinity. According to data, Mg2+-ATPase and Ca2+-ATPase activities generally increased in chronic exposures, depending upon individual and combination effects of salinity and Hg2+. Na+/K+-ATPase activity showed opposite reactions in acute and chronic durations.