Bioaccumulation of lead nitrate in tissues and its effects on hematological and biochemical parameters of Clarias gariepinus

Clarias gariepinus, weighing 119.18 ± 5.21 g, were exposed to 0%, 20%, 40%, and 60% of the LC(50) lead nitrate, Pb(NO(3))(2), which represents the following treatments 0 (control), 16, 32, and 48 mg/l, respectively, for a period of 10 and 20 days. The results showed that the bioaccumulation of Pb(NO(3))(2) in gills were significantly increased (p < 0.05) after 10 days having 0.17 ± 0.07, 5.05 ± 1.04, 6.01 ± 0.82, and 9.61 ± 1.76 mg/100 g wet weight, respectively, for the treatments. However, after 20 days these values increased ((0.17 ± 0.07, 4.34 ± 1.27, 10.83 ± 0.97, and 19.18 ± 2.40 mg/100 g) for 0%, 20%, 40%, and 60% of LC(50) Pb(NO(3))(2) respectively. There was an increase with each increasing concentration level of Pb(NO(3))(2) as compared with that of the control group. The accumulation of Pb(NO(3))(2) in the liver, showed a significant increase (p < 0.05) with the increasing period of exposed and Pb concentration with LC(50) values ranging between 3.32 ± 0.91 and 4.42 ± 0.78 after 10 days as compared with that of the control group 0.08 ± 0.02 mg/100 g wet weight. Although white muscles and skin displayed lower values of bioaccumulation than gills and liver after 10 days, after 20 days the results were slightly more increased in the white muscles than in the skin. However, the observed pattern of increase was the same compared to that of the control group. Therefore, hematological parameters, such as red blood cells (RBCs), hemoglobin (Hb), and hematocrit (Hct) showed significant (p < 0.05) concentration-dependent decreases in fish exposed to Pb(NO(3))(2) during both periods. However, the values of white blood cells (WBCs) showed a significant reduction when levels of Pb concentration increased. Hepatic enzyme activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) displayed a significant increase with increasing concentrations and exposure time.