Enzymatic Activity and Protein Content Changes in Tilapia from Ogun River Exposed to Agricultural Run-off

Enzymatic Activity and Protein Content Changes in Tilapia from Ogun River Exposed to Agricultural Run-off

Abstract

Agricultural activities release several chemicals into nearby water bodies, often harming aquatic life. This study examines how agricultural run-off affects the enzymatic activity and protein content of Tilapia fish found in the Ogun River, Ogun State, Nigeria. Fish samples were taken from different points along the river and analyzed for liver and gill enzyme activities — alanine aminotransferase (ALT), aspartate aminotransferase (AST), and catalase (CAT) — using standard laboratory methods. Total protein levels were also measured. The results showed that fish collected from areas exposed to agricultural run-off had higher ALT and AST levels but lower total protein compared to those from cleaner sections of the river. These findings indicate that pollution from farms stresses fish metabolism and affects their overall health. The study emphasizes the need for better control of agricultural waste and regular water quality monitoring to protect aquatic ecosystems.

Keywords: Tilapia, Ogun River, enzyme activity, protein content, agricultural pollution, biochemical stress.

CHAPTER ONE

1.0 Introduction

Agriculture supports food production and local economies, yet it also contributes to water pollution when fertilizers and pesticides are washed into rivers. In Ogun State, the Ogun River receives large amounts of agricultural run-off due to nearby farms. This run-off contains nutrients and toxic substances that disturb aquatic balance. Over time, these pollutants can alter the biological and chemical makeup of fish and other aquatic organisms.

Fish serve as good indicators of environmental pollution because they respond quickly to changes in water quality. Changes in their enzyme activity and protein content often reveal early signs of stress. Enzymes such as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) play roles in amino acid metabolism, while catalase (CAT) helps protect cells against oxidative damage. When fish live in polluted water, these enzymes may increase or decrease, showing signs of metabolic disruption. Likewise, reduced protein levels can reflect nutritional or physiological stress.

Furthermore, when agricultural waste enters rivers, it increases nutrient levels, leading to eutrophication and oxygen depletion. These changes can weaken fish health and reduce water quality. In Ogun State, the rapid growth of agriculture and lack of proper waste management have made the Ogun River a hotspot for contamination. Studying how this pollution affects fish biochemistry provides insight into the river’s ecological condition and the potential health risks of consuming fish from such areas.

1.1 Background to the Study

The Ogun River supports fishing, farming, and domestic water use for nearby communities. Unfortunately, increasing agricultural activities have led to heavy use of fertilizers, herbicides, and pesticides. When rain falls, these substances flow into the river, carrying harmful chemicals. These pollutants accumulate in the tissues of fish, altering their biochemistry. Monitoring enzyme activity and protein concentration in fish like Tilapia provides a simple yet effective way to assess pollution effects.

Understanding these biochemical responses helps to identify early signs of stress before visible damage occurs. Moreover, these findings can guide environmental policies and promote safer farming techniques that reduce pollution risks.

1.2 Statement of the Problem

The Ogun River is facing increasing pollution from agricultural run-off, yet there is limited biochemical data on how this affects local fish species. High levels of fertilizers and pesticides can alter fish metabolism, damage vital organs, and reduce protein synthesis. Since Tilapia is both a common food fish and an environmental bioindicator, there is a need to study its enzymatic and protein responses to agricultural contamination in this river.

1.3 Aim and Objectives of the Study

Aim:
To evaluate the impact of agricultural run-off on enzymatic activity and protein content in Tilapia from the Ogun River.

Objectives:

1. To measure the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and catalase (CAT) in Tilapia from selected river sites.

2. To determine total protein content in fish samples from polluted and less polluted areas.

3. To compare the biochemical responses of fish from contaminated sites with those from clean water areas.

4. To identify relationships between pollution levels and biochemical markers in fish.

1.4 Research Questions

1. How does agricultural run-off influence enzyme activity in Tilapia from the Ogun River?

2. What are the differences in protein content between fish from polluted and clean areas?

3. Can enzyme and protein changes serve as early indicators of water pollution?

1.5 Significance of the Study

This research provides scientific evidence on how agricultural pollution affects aquatic life. The results will help environmental regulators, farmers, and researchers understand the effects of fertilizers and pesticides on river ecosystems. It will also promote safer agricultural practices that protect water resources and public health. Moreover, the findings will contribute to the growing body of knowledge on the biochemical impacts of pollution in tropical freshwater systems.

1.6 Scope of the Study

The study focuses on Tilapia fish collected from different parts of the Ogun River, especially where agricultural activities are intense. It limits its assessment to biochemical parameters such as enzyme activity and protein levels, without extending to histological or molecular analyses. The study aims to establish a link between pollution exposure and measurable biochemical changes.

1.7 Definition of Terms

• Agricultural Run-off: Water from rainfall or irrigation that carries fertilizers, pesticides, and farm waste into nearby rivers or streams.

• Enzymatic Activity: The rate at which enzymes perform chemical reactions essential to cell metabolism.

• Protein Content: The amount of total protein found in tissue, used to measure nutritional and physiological status.

• Oxidative Stress: Damage to cells caused by an imbalance between antioxidants and free radicals.

• Tilapia: A common freshwater fish species used for environmental monitoring due to its sensitivity to pollution.