Water is vital to the existence of all living organisms, but this valued resource is increasingly being threatened as human populations grow and demand more water of high quality for domestic purposes and economic activities. The quality of any body of surface or ground water is a function of either or both natural influences and human activities. It is now generally accepted that aquatic environments cannot be perceived simply as holding tanks that supply water for human activities. Rather, these environments are complex matrices that require careful use to ensure sustainable ecosystem functioning well into the future. Rivers are the most important freshwater resource for man. Unfortunately, river waters are being polluted by indiscriminate disposal of sewerage, industrial waste andplethora of human activities, which affects their physico‑chemical characteristics and microbiological quality. Pollution of the aquatic environment is a serious and growing problem. Increasing numbers and amounts of industrial,agricultural and commercial chemicals discharged into the aquatic environment have led to various deleterious effects on aquatic organisms. Aquatic organisms, including fish accumulate pollutants directly from contaminated water and indirectly via the food chain.
Phytoplanktonalgaearefree-floating microscopic plants which, obtain chlorophyll and grow byphotosynthesis in the presence of sunlight and lacks roots, stems and leaves (Lee, 1999;
Nwankwo, 2004; Effiong and Inyang, 2016). It is the power-house of the aquatic food web. Phytoplankton, like land plants arebarely distributed completely at random due to variations in reproductive pattern, microhabitat preference orgrazing. Most phytoplankton has an uneven distribution despite the fact that they are continuously mixed by watermovement. Phytoplankton abundance and distributions have been reported in some estuaries of South-Eastern Nigeria (Ekwu and Sikoki,2006; Akoma, 2008; George et al., 2012).Zooplanktons are the animal component of plankton and form a vital link in aquatic food chains between microscopic photosynthetic algae and fish. They are also food for sea birds. Zooplanktons form major part of fish natural food as main source of proteins (Markovic,2003). Zooplanktonic fauna are the major mode of energy transfer between the phytoplankton and the fish (Howick and Wilhm, 1984).
Physicochemical parameters influence both vertical and horizontal migration of aquatic organisms. It affects their distribution, diversity and feeding. Physicochemical parameters of water are determined largely by the climate, geochemical and geomorphological conditions of catchment basin. Factors such as temperature, pH, DO, transparency, and electrical conductivity form part of abioticcomponents of an aquatic ecosystem. When water temperature is outside tolerable range, abundance of zooplankton is affected directly (Abdullahi, 1998;Imam et al., 2011).
High acidic or high alkaline pH could result to the death of aquatic organisms.
Pollution by heavy metals occurs largely from industries, trade waste, agricultural wastes and automobile exhausts. It has been found that these wastes are large in magnitude and varied in types.They include large quantities of raw materials, byproducts, co-products and final product (Odu, 1996). Mining areas are the chief areas where metal pollution readily occur, in which the surrounding land receives it first. Apart from natural occurrence e.g. erosion, metal pollution on land is a direct result of man’s activities.
The Asa River constitutes the bulk of water being used in Ilorin and its environs either treated or otherwise. Somewhere along the course of the River is Asa dam where the water is treated and sent to the public for use. However there are some industries and establishments located along the course of the River in Ilorin that empty their waste discharges into this river either treated or otherwise. There is conspicuously a soap and detergent industry, two beverage industries, a major hospital, a major market and a lot of farm practices are carried out along the bank of the River, to mention a few.
The study is designed to estimate the abundance of various planktonic groups as well as to assess the variations in abundance and distribution of various planktonic groups across the sampling stations. Most fresh water organism in Nigeria are threatened by anthropogenic activities (Ibrahim et al, 2009), this study is on the abundance and diversity of plankton in Asa, Agba, and Oyun rivers. These rivers flow through residential areas, industries, agricultural areas whose activities include, channeling of domestic and industrial waters into the rivers. In dry seasons, people in the environment and neighboring communities resort to the use of the river for agriculture, livestock and human consumption due to insufficiency of pipe borne water. These activities of the neighboring communities may affect the physico-chemical conditions and biological parameters (planktons) of the water. Therefore there is a need to investigate the biological composition of the rivers and also its physio-chemical conditions.
- AIM OF THE STUDY
The aim of this study is to investigate the abundance and diversity of planktons, as well as its Physio-chemical parameters and some heavy metals like Zinc, Lead, Copper, Magnesium and Iron in Asa, Oyun and Agba Rivers, Ilorin, Kwara State
OBJECTIVE OF THE STUDY
- To access the physico-chemical parameters status of Asa ,Oyun and Agba river.
- To determine the distribution of phytoplankton in Asa, Oyun and Agba Rivers.
- To determine the distribution of zooplanktons in Asa, Oyun and Agba Rivers.
- To ascertain the heavy metals present in the sediment of the Rivers.