Assessment of effluent discharge from fishing activities in Asejire Reservoiroyo State, Southwest Nigeria

Abstract

The effect of the fish farming activities on the downstream section of the Asejire reservoir were evaluated by studying the changes in the water quality parameters from the upstream fish farm to the  downstream of the fish farm. The study was carried out over the course of the two seasons synonymous with the Nigerian climate (dry and wet).The reservoir was divided into three sampling points, the upstream station situated upstream from the fish farm and the downstream station situated downstream from the fish farm. 6 samples were taken from each sampling station and a total of 12 samples were collected throughout the period of the study. Anthropogenic activities in the reservoir tends to affect the water quality of the reservoir. From this study, results showed that Dissolved oxygen and pH values decreased downstream while other parameters such as ammonia, nitrate, nitrite, phosphate, Total Dissolved Solids (TDS), Electrical Conductivity (EC), Temperature, Chemical Oxygen Demand (COD), Total Colony Count (TCC), Coliform Organisms (CO) and Escheriachia Coli increased downstream most notably during the dry season. Dissolved Oxygen ranged from 6.93-6.46mg/L, Phosphate from 0.15- 0.16mg/L, TCC from 91.33- 08.66cfu/ml, CO from 35.66-67.33 and E.Coli from 13-24cfu/ml upstream and downstream respectively and fell outside the WHO guideline for drinking water. There is no significant variation in the values of the parameters upstream and downstream during the wet season but COD values of 250.66-242.66mg/L fell outside the WHO standard. From the results obtained, it was established that water from the Asejire reservoir is not fit for human consumption due to its high bacteriological loads.