Bioaccumulation of Heavy Metals by Clarias gariepinus (African Catfish) in Asa River, Ilorin, Kwara State.

Olaniyi Afolabi Opasola,Sunday Asabi Olawale,Solomon Olayinka Adewoye,Ayodeji Yusuf Iyanda,Adedotun Timothy Adeolu

doi:10.5696/2156-9614-9.21.190303

Olaniyi Afolabi Opasola, Sunday Asabi Olawale + Show 3 more

Open Access

https://doi.org/10.5696/2156-9614-9.21.190303

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Abstract

Background.Harmful wastes and other dangerous industrial by-products constitute major sources of environmental pollutants in Nigeria. Industrial pollutants discharged into the environment contain organic and inorganic pollutants in dissolved, suspended and insoluble forms. Fishes are known for their innate potential to bioaccumulate heavy metals in their muscles and various organs.Objectives.The present study aimed to assess the bioaccumulation status of heavy metals in selected organs and tissues of African catfish in Asa River, Ilorin, Kwara State, Nigeria.Methods.Three sampling points (A (upstream), B (point of discharge) and C (downstream)) were selected in relation to industrial effluents that enter the river. African catfish were randomly harvested from each site using fishing nets at the three sampling points. The samples were digested and subjected to atomic absorption spectrophotometric analysis. Statistical analysis of data was carried out using the Statistical Package for the Social Sciences (SPSS) version 20 and two-way analysis of variance (ANOVA) to compare data among sites and organs.Results.The present study found that the bioaccumulation level of heavy metals in selected organs and tissues of African catfish in Asa River, Ilorin, Kwara State, Nigeria was very high and the level of accumulation of heavy metals increased downstream. Accumulations were much higher during the dry season (especially in the month of February) and relatively low during the peak of the rainy season.Conclusions.Heavy metals at elevated levels in the aquatic environment can accumulate in fish tissues and organ, and therefore fish from the Asa River are not fit for human consumption.Competing Interests.The authors declare no competing financial interests.

Highlights

In Nigeria and throughout the globe, industries are crucial to economic development and play an important role in raising living standards
The present study aims to assess the bioaccumulation status of heavy metals in African catfish from three sampling sites in Asa River, Ilorin, Kwara State, Nigeria
The bioaccumulation of metals in the tissues of African catfish from Site A and C was in the order of gills > bones> head regions and muscles

Summary

Introduction

In Nigeria and throughout the globe, industries are crucial to economic development and play an important role in raising living standards. Pollution of the aquatic environment with heavy metals has become a worldwide problem because the metals are indestructible and most have toxic effects on organisms.[1,2,3] Heavy metals enter rivers and lakes from a variety of sources such as rock and soil directly exposed to surface water, in addition to the discharge of treated and untreated liquid wastes into water bodies These harmful wastes and other dangerous industrial by-products constitute major sources. The present study found that the bioaccumulation level of heavy metals in selected organs and tissues of African catfish in Asa River, Ilorin, Kwara State, Nigeria was very high and the level of accumulation of heavy metals increased downstream. Heavy metal ions do not degrade into harmless end products and are toxic to humans and the surrounding environment.[5,6]

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