Impact of heavy metals on Oreochromis niloticus fish and using Electrophoresis as Bio-indicator for environmental pollution of Rosetta branch, River Nile, Egypt

Abstract

In the present work, samples of water and fish were collected seasonally from the river Nile at El- Qanater El- Khyria as non-polluted site and from downstream of El-Rahawy drain (El-Qatta) as a polluted drain during the year 2016. The concentration of metals (Fe, Zn, Cu, Pb, Mn and Cd) in water and their accumulations in fish muscles were measured. Electrophoresis pattern of Oreochromis niloticus including: protein pattern, calcium pattern and β -esterase were detected. There were increases in heavy metals concentrations and their accumulations in muscles of O. niloticus inhabiting the water of El-Qatta station. In the present study, results revealed increased concentrations of studied metals in water and fish samples mainly during the winter season. Accumulations of the heavy metals were in the following order: Fe> Zn> Mn> Pb> Cu> Cd. The values of Fe, Cu, Pb, Mn, Zn and Cd were higher than the permissible limits in water, while Fe, Pb and Zn exceeded the permissible limits in fish muscles, especially those of El-Qatta station. Results of electrophoretic protein pattern showed similarities in arrangement of the bands in liver and muscles tissues in fishes taken from both locations (A and B), with a difference arrived to 45.4% in the liver and 48.1% in the muscle. While, electrophoretic calcium pattern showed a significant difference arrived to 66.1% in the liver and 61.6% in the muscle, the electrophoretic β -esterase showed a significant difference arrived to 74.5% in the liver and 70.0% in the muscle. The bioaccumulation factor in winter was higher than that in summer. The Hazard Index (HI) and Hazard Quotient (HQ) values were below the acceptable limits (HQ and HI < 1), which indicate that the metals in O. niloticus at El- Qanater El-Khyria (0.4873), do not have any human health risk concern, while Hazard Indices (HI) for the analyzed heavy metals were higher than the acceptable limit (HI<1) at El-Qatta station (1.5869), though, the metals cumulative risk impacts gave an alarming sign particularly at high fish consumption rates.