ABSTRACT

 

 

The aim of this study is to determine the effects of Lead Nitrate and crude oil on the juveniles of the African catfish Clarias gariepinus. The study was based on results of acute toxicity tests, haematological, histopathological, and enzyme analysis. The acute toxicity tests lasting 96 hours were performed on the Clarias gariepinus of mean weight 138 ± 12g and mean total length of 28 ± 1.5cm. The LD50 of Lead Nitrate was 57.5mg/L while LD50 of crude oil was 823.3µl/L (ppm). The experimental fishes used for the chronic toxicity assay were 27.38 ± 0.43cm – 31.18 ± 3.76cm in mean length and 126 ± 3.22g to 151 ± 0.67g in mean weight. They were divided into groups A, B, C, D, and E of 20 fishes each. Group A was kept as control. Group B was exposed to 20mg/L of Lead Nitrate. Group C was exposed to 35mg/L of Lead Nitrate. Group D was exposed to 300ppm while E was exposed to 600ppm of crude oil. Water quality parameters, Dissolved Oxygen (DO), temperature, and pH were monitored. The body weights of the fishes were measured weekly. The experiment lasted for 70 days. Blood samples were collected for haematological and enzyme analysis before dissection of the gills and liver for histopathological examination. The control group showed significant increase in body weight at (P < 0.05) 150g ± 0.85 to 250g ± 7.07 while the treated groups showed significant reduction in body weight, 151g ± 0.67 to 75g ± 10.61. There was no significant difference (P> 0.05) in the water quality parameters DO, temperature, and pH between the control and treated groups. Significant differences (P<0.05) occurred in haemoglobin, haematocrit, red blood cells (RBC) and white blood cells. No significant differences (P> 0.05) occurred in the RBC indices, mean corpuscular haemoglobin concentration(MCHC), mean corpuscular haemoglobin(MCH), mean corpuscular Volume(MCV). Significant differences (P< 0.05) occurred between the serum enzymes: aspartate transaminase(AST), alanine transaminase(ALT), alkaline phosphatase(ALP) of the control and treated groups. The histological sections of the gills and liver showed histopathological lesions in the treated groups. These include hyperaemia, Oedema, necrosis, degeneration and cellular infiltration. The overall effect of Lead Nitrate and Crude oil on the juveniles of Clarias gariepinus was anaemia and weight loss.

 

 

 

 

 

 

 

 

 

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TABLE OF CONTENTS

 

 

 

 

Title Page -

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Certification Page

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Approval Page

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Dedication

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Acknowledgement

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Abstract  -

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Table of Contents

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-viii-xii

CHAPTER ONE

 

 

 

 

 

 

 

 

 

1.0

INTRODUCTION

 

 

 

 

 

 

 

1

1.1

Statement of Problem

 

 

 

 

 

 

3

1.2

Aims and Objectives of the Study

 

 

 

 

4

CHAPTER TWO

 

 

 

 

 

 

 

 

 

2.0

Review of Related Literature

 

 

 

 

 

5

2.1 The use of Fish for Toxicological Studies

 

 

 

5

2.2

The Blood as Target Tissue for Toxicological Study

 

8

2.3

Gills as Target Organs for Toxicological Study

 

 

10

2.4

The Fish Liver

 

 

 

 

 

 

 

 

11

2.5

Enzymes as Biomarkers for Aquatic Toxicology

 

13

2.6

Fish histopathology

 

 

 

 

 

 

 

15

 

 

 

 

 

 

 

 

 

 

 

9

2.7

Lead Toxicity

15

2.8

Crude Oil Toxicity

17

CHAPTER THREE

 

3.0

Materials and Methods

18

3.1

Determination of LD50 of lead Nitrate and Crude Oil

19

3.2

Experimental Design

22

3.3.

Haematological Examination

26

3.4

Enzyme Analysis

28

3.5

Histopathological Examination

28

3.6

Statistical Analysis

29

CHAPTER FOUR

 

4.0

RESULTS

30

4.1

Weight of Experimental Fish during Exposed

 

 

to Lead Nitrate and Crude Oil

30-33

4.2

Water Quality Parameters of Exposure Aquaria

35-37

 

4.3      Haematological Responses of Experimental

 

Clarias gariepinus after 70 days exposure to Lead

 

 

Nitrate and crude oil

38-40

4.4

Enzyme Assay

41-43

4.5

Summary of Results

44

 

 

10

4.6

Histopathological Findings

46-55

CHAPTER FIVE

 

5.0

Discussions

56

CHAPTER SIX

 

 

6.0

SUMMARY & RECOMMENDATIONS

64

6.1

Summary

 

64

6.2

Recommendations

64

 

References

66-78

 

Glossary

 

79-80

 

Appendices

81

LIST OF TABLES

 

Table 3.1:

LD50 of Lead Nitrate

19

Table 3.2:

LD50 of Crude Oil

21

Table 4.1:

Mean weight of experimental fish

 

 

 

during exposure to Lead Nitrate

 

 

 

and Crude Oil

30

Table 4.2:

Water Quality Parameters of Exposure

 

 

 

Aquaria

81

Table 4.3

Haematological Responses (Mean ± Sem) of

 

 

Clarias Gariepinus after 70days Exposure to

 

 

Lead Nitrate and Crude Oil

82

 

 

 

11

Table 4.4:

Enzyme Assay

83

LIST OF FIGURES

 

Figures 1:

Regression lines of changes in mean weight of

 

experimental  fish  during  exposure  to  Lead

 

Nitrate

31

Figure 2:

Regression lines of changes in mean weight of

 

experimental fish during exposure to Crude oil

 

 

32

Figure 3:

Graph showing changes in mean weight of the

 

experimental fish

33

Figure 4:

Dissolved Oxygen of Exposure Aquaria

35

Figure 5:

Hydrogen Ion Concentration (pH) of Exposure

 

Aquaria

36

Figure 6:

Temperature of Exposure Aquaria

37

Figure 7:

Haemoglobin of Clarias gariepinus after 70 days

 

exposure to Lead Nitrate and Crude oil

38

Figure 8:

Haematocrit of Clarias gariepinus after 70 days

 

exposure to Lead Nitrate and Crude oil

39

Figure 9:

Red Blood Cell Count of Clarias gariepinus

 

 

after 70 days exposure to Lead Nitrate

 

 

and Crude oil

40

Figure 10:

SGOT (AST) of Clarias gariepinus after

 

 

70 days exposure to Lead Nitrate and

 

 

Crude oil

41

 

 

12

Figure 11:

SGPT (ALT) of Clarias gariepinus after 70 days

 

exposure to Lead Nitrate and Crude oil

42

Figure 12:

Alkaline Phosphatase of Clarias gariepinus

 

 

after 70 days exposure to Lead Nitrate

 

 

and Crude oil

43

LIST OF PLATES

 

Plate 1:

Experimental Setup

24

Plate 2:

Gill Section of Control Fish

46

Plate 3:

Gill Section of 20mg/l Pb (NO3)2 Treated

 

 

Group

47

Plate 4:

Gill Section of 35mg/l Pb (NO3)2 Treated

 

 

Group

48

Plate 5:

Gill Section of 300ppm Crude Oil treated

 

 

Group

49

Plate 6:

Gill section of 600ppm Crude Oil Treated

 

 

Group

50

Plate 7:

Liver section of Control Fish

51

Plate 8:

Liver section of 20mg/l Pb(NO3)2 group

52

Plate 9:

Liver section of 35mg/l Pb (NO3)2 group

53

Plate 10:

Liver section of 300ppm crude oil group

54

Plate 11:

Liver section of 600ppm crude oil group

55

 

 

13

CHAPTER ONE

 

 

INTRODUCTION

 

 

Trace amounts of metals occur naturally in water, however waste water from mining, chemical industries and Agriculture, etc, are the main sources of pollution. Additionally, rain contaminated by burning fossil fuels is another source of pollution (Pitter, 1999). In fish, the route of heavy metal entry is either through the gills or mouth. The blood carries these heavy metals to different organs or systems hence haemotological studies and histopathological examinations have been considered as valuable diagnostic tools in clinical biochemistry, physiology, genetics and medicine. For many years, these have been used to investigate disease or metabolic alterations (Bansal et al., 1979).

 

Physico-morphological changes in the blood indicate the changes in the quality of the environment, therefore blood parameters are important in diagnosing the functional status of animals exposed to toxicants (Borane and Zambare, 2006).

 

 

 

 

 

 

 

14

Fishes are particularly sensitive to water borne environmental contamination and are recognized as a useful model for indicating water quality (Mathis and Kervern, 1975).

 

Lead, a biologically non-essential metal is relatively abundant in nature and of extensive use in modern times (Todd et al.,

 

1996). The build up and transportation of lead in water, atmosphere and sediment result in bioaccumulation of the metal in various pockets of food chain. Sub lethal concentrations of lead cause toxicity which results into oxidative damage in fish tissues. It produces oxidative stress through the generation of free radicals in which reactive oxygen species (ROS) are most important in causing damage to cells and tissues (Verma and Belsare, 2005).

 

Crude oil pollution is common all over the world, particularly endemic in countries whose economies are dependent on the oil industry. In Nigeria oil industry, operations are both onshore and offshore and the oil terminals as well as most refineries are located in the Niger Delta region, hence more than 90 percent of oil related activities take place in this region (Imevbore and Adeyemi, 1981). According to the River State Environmental

 

 

15

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