Investigation of protective effect of zeolite on mercury toxicity using by biochemical parameters in blood tissue of Oreochromis niloticus

In the present work, blood biochemical parameters of Oreochromis niloticus were used to assessment protective effects of zeolite (Zeo) on toxicity of mercury (Hg). For this purpose fish were exposed to 0.01 and 0.05 mg/L Hg and 0.01 mg/L Hg+0.01 g/L Zeo and 0.05 mg/L Hg+0.05 g/L Zeo for 4 and 21 days. It was measured alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and cortisol, glucose, total protein, sodium, chlorine and potassium levels in obtained blood serum. In the exposures of mercury alone and mercury+zeolite mixtures, significant changes were determined in all analyzed parameters due to medium concentration and exposure period. ALT and AST activities significantly increased at 4 and 21 days in both exposure concentrations of mercury and at 21 days in higher concentration of mercury+zeolite mixture (P˂0.05). In the mercury alone, levels of cortisol and glucose elevated after the both exposure periods (P˂0.05). The exposures of mercury+zeolite mixtures increased the cortisol level at 4 days and glucose level at 21 days (P˂0.05). At the both exposure periods in the mercury+zeolite mixtures, it not determined significant alteration in the total protein levels (P˃0.05), while they decreased in higher concentrations of mercury alone (P˂0.05). In the exposure of mercury alone especially in its higher medium concentraion, levels of sodium and chlorine declined, while level of potassium elevated (P˂0.05). However it was not determined significant alterations in levels of all analysed these electrolytes in exposure of mercury and in combination with zeolite (P˃0.05). The results showed that the observed changes in activities of serum enzyme and levels of metabolites and electrolytes of O. niloticus were higher in the mercury alone than mercury+zeolite mixture and zeolite partially or totally played a protective role aganist the toxic effect of Hg.