ALGAL DIVERSITY AND WATER QUALITY OF ASATA RIVER ENUGU, ENUGU STATE, NIGERIA

ALGAL DIVERSITY AND WATER QUALITY OF ASATA RIVER ENUGU, ENUGU STATE, NIGERIA

ABSTRACT

An assessment of the physicochemical, parameters, algal diversity and bacterial flora of Asata River Enugu, Enugu State, Nigeria was carried out for six months. Water samples and periphyton were collected fortnightly from four locations namely: Okpara Coal Mine, University of Nigeria Teaching Hospital (UNTH) Old Site, Ogbete market and Ogui and analysed using standard procedures. Algal diversity and species richness were determined using Shannnon – Wiener index. Spread plate method on Macconkey agar was used for bacterial count. Results showed monthly variations (P≤0.05) in air temperature, velocity, alkalinity, aluminum, dissolved oxygen, biological oxygen demand, chemical oxygen demand, calcium, pH, total suspended solids, iron, lead and zinc, at the various locations. Significant (P≤0.05) positive (colour and depth, transparency, iron and Bacillariophyta) and negative (pH and algal divisions; lead and Bacillariophyta; mercury and Cyanophyta) correlations were also observed among some parameters investigated. Thirrty-four algal taxa belonging to four divisions in the following decreasing order: Bacillariophyta (33 %), Chlorophyta (32 %), Euglenophyta (21 %), and Cyanophyta (14 %) were encountered. Some pollution tolerant algae such as Gomphonema, Nitzschia, Navicula, Surirella, Euglena and Oscillatoria were dominant. Based on Shannon–Wiener index, the water at UNTH and Ogbete were classified as mesoptrophic whereas, Okpara coal mine and Ogui were classified as eutrophic. The diversity index showed no complete evenness in the river. The lowest and highest enteric bacterial counts (1.029 × 104 ± 1.174 and 5.05 × 104 ± 1.472) were observed in August and November respectively. Gram – positive and gram – negative bacteria such as Escherichia, Salmonella, Micrococcus, Proteus and Enterobacter were isolated. Escherichia was dominant indicating fecal pollution. pH was within the permissible limit; iron, lead and phosphate beyond the limit; and calcium, magnesium, biological oxygen demand, chemical oxygen demand, dissolved oxygen below WHO standard for drinking water, indicating that the river was eutrophic.