Seasonal variation of organochlorine pesticides residue in water and silver catfish (Bagrus Bajad fabricius, 1775) from Ajiwa Reservoir, Katsina State

Abstract

Water is one of the major components of environmental resources that are under threat either from over exploitation or pollution  exacerbated by human activities. Organochlorine pesticides (OCPs) are major contaminants of inland water bodies and could lead to  pollution if they accumulate over time. This study was carried out to investigate seasonal variation in OCPs residue in water and its bioaccumulation in gills and muscles of the silver catfish (Bagrus bajad Fabricius, 1775) from Ajiwa reservoir, Katsina State, Nigeria,  between February and September 2022. The fish and water samples were obtained from three major fishing landing sites near the  reservoir; Kadaji, Gamji and KunduWaje. The organochlorine pesticide residue in the fish and water samples were extracted, clean up with Silica gel and analyzed with a gas chromatograph with Ni electron capture detector. The data obtained from the gas  chromatography (GC) analysis were presented using descriptive statistics while T-test was used to compare each of the OCPs between  the two seasons. The seasonal difference showed significantly higher amount of gamma-chlordane and endosulfan in gills; aldrin in  muscles; methoxychlor and endosulfan in water in wet season compared to dry season. The results indicated that there is presence of  some organochlorine pesticides in the water from the reservoir, gills and muscle of B. bajad at various concentrations. However, the  concentrations are all below the recommended safety limits, nonetheless, continuous monitoring and discouragement of the use of OCPs  in and around the reservoir is recommended to prevent it from getting to hazardous level.