Assessment of physiological and antioxidant responses in African catfish, Clarias gareipinus as biomarkers of metal pollution in River Nile

Abstract

The present study was planned to assess the harmful effects of heavy metals on the physiological/antioxidant statuses and histopathological alterations of African catfish, Clarias gareipinus collected from two polluted sites in River Nile, Egypt; El-Rayah El-Tawfeky (Industrial polluted site) and Moshtahr (Agricultural polluted site) as well as, El-Qanater El-Khayriyah (Reference site) during spring and summer 2015. Results revealed marked (P < 0.05) variations in cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), and zinc (Zn) in water samples among sites. The overall pollution was ordered as agricultural polluted site, industrial polluted site, and reference site. Serum level of glucose, creatinine, urea, uric acid, as well as aspartate transferase (AST), alanine transferase (ALT), and alkaline phosphatase (ALP) were significantly (P<0.05) higher in fish collected from the two polluted sites especially in Moshtahr site during summer season compared to the reference site. On the other hand, serum levels of to tal protein, albumin, globulin, and A/G ratio were significantly lower during both seasons in fish collected from the two polluted sites compared to those of the reference site. Highest reduction in total proteins was more evident during summer in fish collected from Moshtahr site. However, fish tissues of both polluted sites exhibited a significant rise in lipid peroxidase (LPO) and reduced glutathione (GSH) values as well as superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), which were more obvious in Moshtahr site during summer than spring season. Histopathological examination of liver tissues of the collected fish from polluted sites showed vacuolar degeneration of the hepatocytes, haemorrhage, haemosidirin, and focal areas of necrosis compared to the fish from EL- Qanater El- Khayreya. The study indicates that the alterations in the biochemistry profile and antioxidant defense system of African catfish, C. gariepinus can be used as biomarkers of metal pollution for monitoring aquatic life.