WATER QUALITY AND ALGAL BIODIVERSITY OF EBONYI RIVER UDENU L.G.A ENUGU STATE NIGERIA.

ABSTRACT

The physico-chemical and  algal characteristics of the upper reaches of Ebonyi River were studied in four stations over a four- month period from September to December 2014. The physico-chemical parameters: air and water temperatures, colour, depth, rate of flow, transparency, pH, Total Dissolved Solids (TDS), alkalinity, Biochemical Oxygen Demand (BOD5),  Dissolved oxygen (D.O), silica, potassium, phosphate, nitrate, chloride, calcium, lead, iron and mercury were studied using standard methods. Parameters such as colour, calcium, pH, total dissolved solids, alkalinity, chloride, dissolved oxygen, silica, biochemical oxygen demand, phosphate, nitrate, potassium and lead did not significantly differ between the locations (P ≤ 0.05). Air  temperature, depth,  rate of flow  and  transparency differed significantly between locations. All parameters differed significantly between months except depth and rate of flow which did not significantly differ between the months. Mercury was not detected during the study period. A total of twenty nine (29) taxa of algae were observed in the study.   Algal abundance showed  the  following  order:  Heterokontophyta >  Chlorophyta >  Cyanophyta  > Euglenophyta > Cryptophyta. Based on Shannon-Wiener diversity index, the water in the four locations studied is moderately polluted. The study revealed that though Ebonyi River is not heavily polluted, the fluctuations of the investigated parameters along the sampling points could be as a result of both anthropogenic and natural activities.

CHAPTER ONE

INTRODUCTION

Rivers  as  water  bodies  are  important  by  being  involved  in  maintaining  a  balance  in  the ecosystem through supporting diverse plankton (phytoplankton and  zooplankton) and  other organisms in the food chain. In the last decades, there has been a growing necessity for the conservation of our resources, especially water. At the same time, growing populations, progressive industrialization and intensification of agriculture are leading to increased pollution of our surface waters (Mohammad and Saminu, 2012).

Adequate and  safe  water  supply  is  therefore a  pre-requisite  for  significant  socio-economic development  of  any  community.  Unfortunately,  in  many  areas  of  the  world,  especially developing countries including Nigeria, it is difficult to obtain a steady source of clean water for drinking and  for  agricultural uses (Akpan-Idiok et  al.,  2012). Rivers are  equally useful in generating electricity,  fisheries, irrigation and  for domestic animals (Zakariya et al., 2011). Water required for domestic consumption should be free from suspended solids and dissolved impurities etc. (Alexander, 2008). Rivers constitute one of the major sources of water supply in the world (Akpan-Idiok et al., 2012).

The assessment and continuous monitoring of the quality of water sourced from rivers can be used to define existing conditions, detect trend and or establish sources of pollution. The quality of water is often affected by rocks, soil and surface through which it flows and anthropogenic (e.g. industrial, agricultural and mining) activities (WHO, 1996; Ibeto and Onianwa, 2011).

Several  studies  revealed  that  these  activities  coupled  with  atmospheric  factors  affect  the suitability of water for all purposes (Faniraan et al., 2001; Daghrah, 2009; Hakim et al., 2009; El-Saeid et al., 2011; Al-Tabbal and Al-Zboon, 2012).  Maitera et al. (2011) pointed out that sources of water supply are susceptible to pollution due to heavy human dependency on them. Urbanization, domestic and industrial activities thus have greatly contributed to increased scale of pollution of rivers and other bodies of water (Ibeh and Mbah, 2007).

Chemical pollutants include heavy metals, which are elements having specific gravity greater than 4.0 that is, at least 5 times that of water (Akan et al., 2010). The most common heavy metals that humans are exposed to are aluminium, arsenic, cadmium, lead and mercury (Akan et al.,

2010). Heavy metals can cause serious health effects with varied symptoms depending on the nature and quantity of the metal ingested (Adepoju-Bello and Alabi, 2005). Excess exposure to these metals can however, be toxic (Akan et al., 2010).

Water physico-chemical parameters are known to affect the biotic component of an aquatic environment in various ways (Ugwumba, 1993). The change in physical characteristics like depth, temperature, transparency and chemical elements of water such as dissolved oxygen, chemical oxygen demand, nitrate and phosphate provide valuable information of the quality of the water, the source(s) of the variation and biodiversity (Mustapha, 2008).

Phytoplankton are microscopic aquatic plants, occurring as unicellular, colonial or filamentous forms, without any resistance to currents and are free-floating or suspended in the open waters (Zakariya et al., 2011). They are important water quality indicators because of their short life cycles, ability to respond to environmental changes and species composition (Dokuli, 2003). Algal abundance can be affected by turbidity levels. High turbidity affects primary productivity,

because turbidity reduces the amount of light penetration which in turn reduces photosynthesis and hence primary productivity (USEPA, 1991; APHA, 1992).

Nutrient  limitation is  important in the  regulation of algal abundance (Hirose et  al., 2003). Therefore, evaluating the physico-chemical and algal constituents of surface waters is essential in appraising their quality and suitability for various purposes (Omo-Irabor and Olabanyi, 2007).

1.1                  STATEMENT OF PROBLEM

Pollution of our environments has long been identified as a major challenge to the sustainability and stability of our ecosystems, especially the aquatic environments. Pollution is a challenge to the health of both aquatic organisms and humans. Human activities constitute greater percentage of the pollution of the  environments including the Ebonyi River. The Ebonyi river passes through the outskirts of the town of Obollo-Afor in Udenu L.G.A. where human activities observed are farming along its’ banks at  some locations, laundry, swimming,   bathing and collection of alluvial soil for constructions. Due to these activities and other natural activities, the physico-chemical parameters and diversity of algae need to be analysed to determine the quality of water. There is also, the need to identify more of our local algal species, which can be used in preparing a checklist of algae in the future.

1.2                    OBJECTIVES OF THE STUDY

The objectives of the study are to:

(i)  Assess the physico-chemical parameters of Ebonyi River

(ii) Identify algal biodiversity of the Ebonyi River.

(iii)Correlate the physico-chemical parameters with algal biodiversity

(iv) determine the trophic status of the Ebonyi River.

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