PROJECT TOPICS ON PHYSICO-CHEMICAL PARAMETERS AND FISH DIVERSITY OF DOMA RESERVOIR, NASARAWA STATE, NIGERIA

ABSTRACT

Study on the physico-chemical parameters and fish diversity of Doma reservoir, Nasarawa State, Nigeria was conducted from July 2012 to June 2014. La Motte Tracer (pocketester) code 1766 was used to determined the values of the pH, salinity, TDS and electrical conductivity while La Motte Fresh Water Aquaculture Test Kit (Model: AQ-2, Code: 3633-

• was used in determining the values of dissolved oxygen (DO), alkalinity, carbon dioxide, chloride, hardness and ammonia-nitrogen. Fish species composition and distribution were determined using a fleet of seven multifilament gill nets in sampling the shore, surface and bottom habitats in the three sampling stations and artisanal catch assessment surveys.
• The study shows that mean values of the physico-chemical parameters obtained were within the acceptable ranges for safe aquatic lives, though there were monthly and seasonal variations in some physico-chemical parameters of water.The mean dry season values for water temperature, transparency, salinity, total dissolved substances, conductivity, hardness and dissolved oxygen were significantly higher (P<0.05) than those of the rainy season while the mean rainy season values for depth, ammonia-nitrogen, alkalinity, carbon dioxide and chloride were higher than those of dry season. The correlation analysis between the physico-chemical parameters studied in Doma Reservoir shows that some parameters exhibited positive relationship while some exhibited negative relationship. Eight families of fish (Cichlidae, Mormyridae, Clariidae, Hepsetidae, Channidae, Cyprinidae, Polypteridae and Mastacembellidae) represented by thirteen species of fish were recorded in both experimental gill net sampling and commercial catches of fishermen in the Doma reservoir. Cichlidae dominated the fish population and Saratherodon galilaeus was the most abundant species of fish (72.5%). In term of species richness, the family Cichlidae has the highest numbers of species represented by five (Saratherodon galilaeus, Tilapia zilli, Oreochromis nilotcus, Hemichromis fasciatus and Pelmatochromis pulcher) followed by Mormyridae represented by two species (Hyperopisus bebe occidentalis and Gnathonemus niger) other families were represented by one species each. The fishing gears used by the local fishermen included gill nets, cast nets, Malian traps and hook and line and means of transport was wooden canoe without engine. The diversity indices shows that the Simpson‟s index (D) was between 0.521 to 0.597, Simpson‟s index of diversity (1-D) was between 0.403 to 0.479, Simpson‟s reciprocal index (1/D) was between 1.675 to 1.919, Shannon‟s index (H) was between 0.858 to 1.007 while Shannon equitability or Evenness (EH) was between 0.391 to 0.437. The length-weight relationship of six fish species study from Doma Reservoir indicated that the fish species exhibited allometric growth pattern and the value of correlation coefficien

• of fish species were higher than 0.900 which indicates strong relationship between length and weight, that is weight increases with increase in length while condition factors (K) of fish species studied shows the fish were in good conditions. The study also showed that the reservoir was productive with the potential fish yield (Y) of 40.76kgha^-1 for the first year, 42.63kgha^-1 for the second and 41.73kgha^-1 for the combined years estimated from morpho-edaphic indices of the reservoir. The need to monitor human activities and fishing intensity on the reservoir, in order not to destroy the fish diversity is recommended. Regulation of number of fishermen operating on the reservoir and the enforcement of using minimum mesh size of 7.6cm or 3” was also recommended.

CHAPTER ONE

INTRODUCTION

1.1         Background of the Study

Nigeria lies between Longitudes 2⁰ 49‟ and 14⁰ 37‟E and Latitudes 4⁰ 16‟ and 13⁰52‟ N of Equator. It is blessed with vast expanse of inland fresh water and brackish ecosystems from the coastal region to the arid zone. Thirteen lakes and reservoirs with a total surface area of 953600 ha representing about 1% of the country have been reported (Olaosebikan and Raji, 1998). They are of significant importance because they hold populations of diverse fish species. Species that are of great commercial value and importance vary in their composition depending on the water body. These species of fish serve as a source of protein and food in the face of ever increasing population in the developing countries. In addition, the lake fisheries had serve as a source of livelihood to the riparian communities and biodiversity of tremendous conservation values.

There are about 268 different freshwater fish species in Nigeria. They inhabit over 34 well-known fresh water bodies (rivers, lakes and reservoirs) which constitute about 12% of Nigeria‟s total surface area put about 94,185,000 ha (Ita 1993). Fish stocks in rivers are generally replenished from their adjacent flood plains after each flood season during which fish breed. Therefore, any natural phenomenon as drought or artificial activities such as dam construction, which eventually affect the natural cycle of flooding, will certainly undermine fish species diversity both in lakes and wetlands. Considering this facts, therefore, that lakes, wetlands and reservoirs are supplied with by their inflowing rivers, the rivers will be characterized by higher species diversity (Ita, 1993).

Fish Production from inland water resources (rivers lakes and streams) is under threat from pollution, habitat alteration and degradation, changes in river flows and over exploitation. According to Wotton (1990), material pollution of rivers is caused by toxic pollutants (heavy metals, phenols, insecticides etc) that have direct adverse effect on aquatic biota and by pollutants that indirectly affects aquatic biota like human and animal wastes which are non-toxic but due to bacterial action on them, dissolved oxygen is used up which harms aquatic biota.

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Studies on water quality center on fish production and aquatic biotic integrity (Boyd, 1982, Abohweyere 1990, King 1998). The notable important physico- chemical parameters are transparency, temperature, dissolved oxygen, suspended solids and dissolved ions (Karr and Dudley 1981). Mustapha (2008) stated that expanding human population brought about by the opportunities of good water supply, irrigation, fish production, recreation and navigation offered by reservoirs has put enormous pressure and stress on the quality of water impounded by the reservoir. The impact of human activities in and around the reservoir is felt by on the unique physical and chemical properties of water on which the sustenance of fish that inhabit the reservoir is built as well as the functions of the reservoir. Water quality deterioration in reservoirs usually comes from excessive nutrient inputs, eutrophication, acidification, heavy contamination, organic pollution and obnoxious fishing practices. The effects of these factors do not only affect the socio-economic functions of the reservoir negatively, but also bring loss of structural biodiversity of the reservoir.

PROJECT TOPICS ON PHYSICO-CHEMICAL PARAMETERS AND FISH DIVERSITY OF DOMA RESERVOIR, NASARAWA STATE, NIGERIA

1.2         Research Problem

Water is one of the major components of environmental resources that are under threat either from over exploitation or pollution exacerbated by human activities on the earth surface (Efe, 2002). Studies in Nigeria have shown that water resources are easily contaminated from anthropogenic activities in most cities (Kaizer et al., 2001, Obasi and Balogun 2001). It has been observed that agricultural wastes, manure, fertilizers and pesticides find their way into streams, rivers and lakes through run-off and therefore enrich the organic content of water bodies (Beadle, 1974 and Gopal et al., 1981) and leading to eutrophication (Mitchell, 1975). Eutrophication becomes nuisance in lakes because of impaired water quality which leads to prolific weeds growth, excessive algal blooms and deteriorating fisheries (Gelin, 1978). In Doma reservoir there are three fishing villages around the reservoir and water treatment plant. The villagers around this reservoir are involved in fishing and agricultural activities where herbicides and pesticides are being used. They also used the reservoir for other activities such as bathing and washing of their cloths, pots and plates. All these activities are likely to alter the quality of water in the reservoir which may in turn affect the life of aquatic organisms.

Jamu and Ayinla (2003) reported that the fish yields of most Nigeria inland waters are generally on the decline. The decline of these fisheries has been attributed to a wide range of causes ranging from inadequate management of fisheries resources to environmental degradation of water bodies. Fishing activities in Doma reservoir is so high and it has been observed that the fishermen are found of using different fishing gears including gill nets of smaller mesh sizes and fishing is all year round without opening and closing season, these activities of fishermen may lead to over-exploitation and possible extinction of certain species.

The length-weight relationship of a fish is basically a measure of its growth pattern or age. Growth is an important component of biological production, which affects overall production directly. Negative changes in growth rates may result in decreased individual health, reproductive success and increased risk of predation and mortality (Onimisi and Oniye, 2010). Information on some aspect of biology of fishes such as Length-weight relationship, fecundity e.t.c of Doma reservoir is scanty.

1.3         Justification

Water quality is determined by the physical and chemical limnology of the reservoir (Sidnei et al., 1992) and includes all physical, chemical and biological factors of water that influence beneficial use of the water. The changes in physical characteristics like the temperature, transparency and chemical elements of water such as dissolved oxygen, chemical oxygen demand, nitrate and phosphate provide valuable information on the quality of the water, the source(s) of the variations and their impacts on the functions and biodiversity of the reservoir. Therefore study on the physico-chemical parameters of Doma reservoir will help provide basic information on the quality of water which could be used in the management of water quality of the reservoir.

Survey of fauna and flora of any water body is necessary because it provides a checklist of organisms present in the water for subsequent exploitation, conservation and sustainable management of the resources. Study on the composition of fish species of Doma reservoir will provide information on the type of fish species present in the reservoir, their abundance diversity and richness which will serve as tool for management of fishery resources of this reservoir.Length-weight relationships data of fishes are useful tools for biologists in fishery assessment and proper management of fish population. Length-weight relationship permits assessment of the biomass from length observations and conversion of growth-in-length equations to growth-in-weight and also is applied to assess the well-being of individuals (Mazaher et al., 2015). Study on Length-weight relationship of fishes of Doma reservoir will help provide knowledge on the sizes of fish species present on the reservoir and their well being. Therefore study on physico-chemical parameters and fish diversity of Doma reservoir will provide information which will serve as a base line for effective management and efficient utilization of its aquatic resources.

1.5         Aim of the Study

The main aim of the research was to study the physico-chemical parameters and fish diversity of Doma reservoir and provide information that may assist in the management and optimum utilization of its aquatic resources.

1.6         Objectives of the Study

The objectives of this study include:

1. To determine the variations in physico-chemical parameters of Doma Reservoir in relation to months and seasons
2. To assess the monthly and seasonal composition of fish species in Doma Reservoir
3.  To determine the ength-weight relationships and condition factor (K) of fish species of the reservoir.
4. To determine the fish species diversity of the reservoir

1.4        Research Hypotheses

The research hypotheses are

1. There is no significant variation in monthly and seasonal physico-chemical parameters of water.
2. There is no significant difference in the monthly and seasonal composition of fish species of Doma reservoir

1. There is strong relationship between length and weight of fish species studied in the reservoir

1. The reservoir is not highly diversified in fish species