Toxicity of lead on tilapia (Oreochromis mossambicus): Oxidative stress and some physiological effects

In this thesis study, the oxidative stress and some physiological effects of lead on tilapia (Oreochromis mossambicus) have been investigated. Fish were exposed to different lead concentration of 0; 0,5; 2,5 and 5 mg L-1 during 14 days. Biomarker (Na+/K+-ATPase, Glutathione, TBARS) and metal accumulation analysis in some tissues (gill, liver, intestine, muscle, brain, kidney) and blood parameters (haemotological, biochemical and immunological parameters) have been studied.During the experiments, it was observed that 2 fish dead in the groups of exposing to lead concentration of 5 mg L-1 towards the end of the experiment, lead accumulation in tissues in the experiment increased in direct proportional duration of exposure and ambient metal concentrations.In vivo effects, Na+/K+-ATPase enzyme activity in some tissues (gill, intestine and brain) in the tilapia exposed to lead concentrations were inhibited while it fluctuated in terms of concentration and duration in some tissues (kidney and muscle).In this study, GSH level has shifted depending on time, exposure duration and tissue types while TBARS level increased in tilapia tissues (except mussel) exposing to lead concentrations of 5 mg L-1 (p<0.05).During 14 days, changes of blood parameters in O. mossambicus exposed to lead concentration were observed depending on exposure time and concentration. Haemotological parameters such as haemoglobin, hematocrit, erythrocyte, neutrophil number decreased (p<0.05) while MCH, MCHC and monosit number increased (p<0.05). Biochemical blood parameters such as lipase, ALP, LDH, AST, total protein, glucose, bilurubin, urea, uric acid, triglyceride, creatinin, chloride and magnesium increased (p<0.05). LDL and calcium levels decreased (p<0.05); ALT, CK, cholesterol, albumin, iron and phosphore fluctuated (p<0.05). Immunological activities such as phagositic activity, phagositic index, NBT, lysozyme activity and myeloperoxidase activity decreased (p<0.05).Conclusion, it was determined that lead heavy metal caused to oxidative stress and tissue damages in O. mossambicus.