CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Muthukumaran and Sukumaran (2005) reported that the activities of man have been responsible for introducing contaminants into the environment in the last few decades. The resulting pollution has led to serious consequences on aquatic life. Apart from the presence of industrial wastes that are sources of constant threat to marine life, the ecological disasters caused by the oil industry while exploring crude oil and accidental discharge of crude oil on high seas is a serious cause for concern (Speight, 1999). The main threat posed to living resources by the persistent residues of spilled oils and water-in-oil emulsions (“mousse”) is one of physical smothering that may consequently lead to depletion of biodiversity in the aquatic environment if adequate remediation is not provided Na-Nakorn et al., (2004) . The animals and plants most at risk are those that could come into contact with a contaminated sea surface . These include aquatic mammals, reptiles and birds that feed by diving or form flocks on the sea as well as aquatic lives on shorelines .

Petrochemical products like fuel and kerosene cause tissues damage and histophathological degradations as the fish show haematological responses to toxicants; and generally, such degradation of histological origin occurs in the gills, livers, heart, kidney and epidermis of animals. Jamalzadeh et al., (2009). Reported sublethal levels of petroleum toxicant have shown a severe rise or fall in the hemoglobin of catfish. Hence hemoglobin is a complex protein found in red blood cells that contains iron molecules. The main function of this hemoglobin is to transport oxygen from the lungs to the body tissues and to exchange the oxygen for carbondioxide, and then transport the carbondioxide back to the lungs where it is exchanged for oxygen. Thus a drop or rise in the hemoglobin level leads to Anaemia, congestion of blood vessel and cellular swelling.    Because the liver of fish can be considered a target organ to pollutants, alterations in its structure can be significant in the evaluation of fish health, and exhibit the effects of a variety of environmental pollutants (Vosyliene, 1999).

Haematological indices in these hybrids are critical  parameters for the evaluation of physiological status and genetic resilience of the fish to resist bacterial infection, fungal and viral disease and withstand intensive culture conditions that compromise immunity. Response to these depends on fish species, age, sexual maturity of fish and diseases Vosyliene (1999). Haematological tests and analysis of serum constituents have yielded useful information for detection and diagnosis of metabolic disturbances and disease conditions in fishes (Jamalzadeh et al., 2009). Like in warm-blooded animals, changes in the blood parameters of fish, occurring from injuries or infections of tissues or organs, can be used to determine extent of the dysfunction or injuries to organs or tissues. However, in fish, these parameters are more related to the response of the whole organism, i.e., to the effect on fish survival, reproduction and growth than discrete organ or tissue (Vosyliene, 1999).

In recent years, variation in haematological indices were used when clinical diagnosis of fish physiology was required to determine the effects of external stressors and toxic substances like petrochemicals due to the close association between the circulatory system and the external environment. Cech et al., (1996) also suggested that haematological and biochemical changes, growth rate and oxygen consumption of fish are used in determining the toxic effects of pollutants.

Hematological studies in fishes have assumed greater significance because these parameters could be used as an effective and sensitive index to monitor physiological and pathological changes induced by natural or anthropometric factors, such as bacteria and fungi infections or pollution of water environment, pathogenicity of the organism. This study therefore is aimed at determining the effect of petrochemical products on the blood of African catfish

1.2  STATEMENT OF PROBLEM

There has been indiscriminate discharge of some of petrochemical by-products that contain mixtures of toxic chemicals in the aquatic environment due to their careless handling, accidental spillage or through underground pipes. This act has harmful effects on the fish population and other forms of aquatic life and may contribute to long term effects in the environment. These are also toxic to aquatic faunas and floras and can also induce severe damage to vital organs and even haematological, hormonal and enzyme disturbances and death. These petrochemical compounds usually concentrated in the tissues of aquatic biota can produce cumulative deleterious effects to man when these fishes are consumed by man.

1.3 OBJECTIVE OF THE STUDY

The objective of this study is to determine the effect of petrochemical by-products (fuel and kerosene) on the blood of African catfish (Clarias gariepinus) in concrete pond constructed at SLT Botanical garden (IMT Enugu) garden as case study

1.4 SIGNIFICANCE OF THE STUDY

The haematological study of toxic chemicals on non-mammalian vertebrates is rapidly expanding for the evaluation of the effects of noxious compounds on aquatic organisms. This research work on the study of the effects of petrochemical by product on the blood  of African catfish will help aquaculturists, toxicologists, students, scientists and fish consumers on the understanding of the effect of petrochemicals on the blood of fishes. It will also help them on the knowledge of how to determine the effects of petrochemicals on fishes and follow suit in the study of other toxic compounds on other aquatic organisms.

1.5 LIMITATION OF THE STUDY

Shortness of time and inadequacy of materials are some of the limiting factors encountered during this work. Hence this work is limited to the determination of the effects of petrolchemical by-products (fuel and kerosene) on the blood of African catfish (Clarias gariepinus) in concrete pond in IMT zoological garden

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