A COMPARATIVE ANALYSIS OF HEAVY METALS IN GILLS AND BONES OF OREOCHROMIS NILOTICUS(TILAPIA) FROM THE QUA IBOE RIVER ESTUARY

A COMPARATIVE ANALYSIS OF HEAVY METALS IN GILLS AND BONES OF Oreochromis niloticus(TILAPIA) FROM THE QUA IBOE RIVER ESTUARY

CHAPTER ONE

1.0     Introduction

1.1     Background of the study

The bioaccumulation of heavy metals in gills and bones of marine organism is an indirect measure of the abundance and availability of metals in the marine environment (Kucuksezgin, 2006). Marine organisms are characterized by a greater spatial ability to accumulate metals compared to bottom sediment, for this reason fish are widely used as bio-indicator for aquatic or marine pollution by metals and have also been used to evaluate ecological risk (Szefer, 2006, Evans, 1993; Kucuksezgin, 2006; Chapman, 1992) therefore chemical analysis of fish from a particular body of water (NOAA, 1988; Raoux, 1999).

Metals such as Cu, Fe, Pb and Zn are regarded as essential trace metals given their valuable roles for metabolic activities in human (Oluwusi-Peter, 2014). Other metals like Cd, Ni and Hg exhibit extreme toxicity even at trace level (Mertan, 1991, Olaifa, 2004). However, it is of interest to note that essential metals is toxic when supplied in concentration more than the optimum levels (FEPA, 1991). Tam and wong (1995) stated that heavy metals contamination of the aquatic environment is a critical concern due to the toxicity of metals and their accumulation in an aquatic habitat. Qua Iboe River is one of the prominent water bodies in Akwa Ibom State Nigeria. The main uses of the river in it catchment include domestic uses, swimming, transportation and fishing. In addition domestic, industrial and agricultural wastes are dumped into the river as such causing contamination and accumulation in the aquatic biota. Among the aquatic fauna, fish is the most susceptible of heavy metal toxicant (Nwaedozie, 1998).

Oreochromis niloticus (Tilapia) is a benthic species and is an important component of the diet of the people of Calabar and its environ because it is available all year round. A number of studies have been carried out on the accumulation of heavy metals in fish and other sea organisms, water and sediments from Cross River system in the past (Asuquo 1999, 1998, 2001) and (Etim and Akpan, 1991; Ntekim, 1993; Nwaedozie, 1998; David and Oku, 2006; Edem, 2008).

1.2     Objectives of the study

1. To determine the presence of heavy metals (Pb, Hg, Cd, Zn, Cr and Cu) in both gills and bones of Oreochromi niloticus from Qua Iboe River estuary.