Effect of Heavy Metal Pollution on the Blood Biochemical Parameters and Liver Histology of the Lethrinid Fish, Lethrinus harak from the Red Sea

Heavy metals in aquatic ecosystems are a matter of serious concern, and adversely affect the fish health. Herein, 44 specimens of the fish Lethrinus harak were trapped in the Red Sea, Saudi Arabia, from a severely polluted site. Another 32 specimens of this fish were trapped from an unpolluted site (reference site). Our results revealed that Co, Cd and Pb were undetectable in water, sediment and fish liver samples from the unpolluted site, while their corresponding concentrations were significantly high in the polluted site. Mean concentrations of other metals (Mn, Fe, Ni, Cu, Zn) in water, sediment and fish liver samples from polluted site were significantly much higher than those from the unpolluted one. In contaminated fishes from polluted site, mean levels of blood biochemical parameters, serum liver enzymes (ALT, AST, ALP, GGT), serum glucose, triglycerides and urea were significantly higher than those in uncontaminated fishes from the unpolluted site, but mean level of serum total protein was significantly lower. Only, significant correlations were found between mean levels of blood biochemical parameters and mean concentrations of Zn, Cd and Pb in the liver of contaminated fishes from the polluted site. Liver of fish from the unpolluted site appeared normal, while that of fish from polluted site appeared abnormal due to sever histopathological alterations.