Assessment of the Effect of Anthropogenic Activities on Aquatic Life in Ugbo-Aiyetoro Water-way, Southwestern Nigeria

Ashiru Olusola Raheemat, Adegbile Moruf Oluwasemiloore and Ayeku Patrick Oluwagbemiga

Background and Objective: The health of a water body is hindered by anthropogenic activities which lead to excess nutrient loading; invariably changing the physicochemical properties of the water. This study investigated the effect of eutrophication on the biodiversity of phytoplanktons and zooplanktons in Ilaje community, Ondo coastal region located in the South-western region of Nigeria in May, 2016. Materials and Methods: The physicochemical parameters and nutrient loading of the water were determined at eight pre-established sampling stations (M1-M8) of approximately 200 m equidistance. A 63 μm mesh plankton net was used to isolate planktons at each sample station. Shannon-Weiner index analysis was done to understand specie evenness and diversity. Results: The physicochemical parameters determined include temperature (30.08-3.89°C), pH (6.26-7.2), dissolved oxygen (DO, 3.26-4.26 mg L^–1), turbidity (18-60 NTU), conductivity (764-4397 μS cm^–1), phosphate (0.11-1.17 mg L^–1) nitrate (17.0797-46.6954 mg L^–1), sulphate (36.6-247.1 mg L^–1), salinity (0.37-2.25 ppt), depth ranges between (1.0-1.8 m), respectively. Eighty eight organisms were identified. Some of the organisms identified include Prorocentrum micans (phytoplankton), Cyclopoid copepod (zooplankton) and Haematococcus spp. (phytoplankton). On aggregate, sample stations M2 and M4 had the highest (14) and lowest (2) numbers of organisms per mL of water, respectively. The correlation analysis of nutrients against phytoplanktons and zooplanktons were weakly negative and weakly positive, respectively. Conclusion: Results implies that the environment is within the mesotrophic range of pollution. The assessment of Ugbo waterway supports the generalization that light intensity and nutrient are crucial to phytoplankton growth in this region. Conclusively, the diversity index of the study area shows that the environment was moderate to less diverse, hence, it is slight to moderately polluted.

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