Evaluation of water genotoxicity using comet assay in two freshwater fish species, Wallago attu and Ompok bimaculatus in Kabul River, Pakistan

Abstract

The investigation determines the pollution status of river Kabul and its effects on the DNA of Wallago attu and Ompok bimaculatus. River Kabul gets pollutants from Amanghar industries and sewages from Mardan, Nowshera and Peshawar. Water and fish samples are taken to study heavy metals and physical parameters. The overall sequence of physical parameters in water samples was TDS>TSS>EC>TA>Cl>Na>pH>K, and that of heavy metals was Zn>Cr>Mn> Fe>Cu>Pb>Ni>Cd. The studied parameters in all the water samples except TSS are within the proposed limits of national environmental quality standards. The overall trend of analysed water samples was C>B>A. The study determines the effects of water pollution on the DNA of Ompok bimaculatus and Wallago attu tissues. Therefore, degrees of DNA damage such as TCS and comet class are studied in gills, liver, muscles, and intestines of Wallago attu and Ompok bimaculatus. The trend of DNA damage in examined tissues was intestine>skin>liver>gills>muscle, and in studied fish species, it was Ompok bimaculatus>Wallago attu. More significant DNA damage was observed in the intestine and smaller in the muscle. More DNA damage was found in Ompok bimaculatus and less in Wallago attu. The investigation recommended detoxifying the effluents and sewages before discharging them in River Kabul.