ABSTRACT
This study was carried out to determine the response of phytoplankton of River Amagba to eutrophication simulation. Water samples were collected for physico-chemical analysis and also periphyton samples for microscopy. The experiment was done with natural phytoplankton population and introduced phytoplankton species. Nutrient spiking was done using a concentration of 2mg/L N, 1mg/L P and 2mg/L+1mg/L NP. Measurement of the algal growth was done spectrophotometrically for every two days interval for a period of two weeks after which the experiment was terminated. Periphyton was examined microscopically. The growth of indigenous phytoplankton and the test algae Chlorella vulgaris and Scenedesmus arcuatus exhibited maximum growth in NP. However, growth in P was next to NP in both indigeneous phytoplankton and Chlorella vulgaris while in Scenedesmus arcuatus growth in N was next to NP. In the two test algae, control had the least growth while for indigenous phytoplankton N had the least growth. The growth response of the algae showed that River Amagba supported the maximum growth of the indigenous phytoplankton and also the introduced phytoplankton (Chlorella vulgaris and Scenedesmus arcuatus) which grew rapidly. Periphyton composition consisted of three divisions namely, Chlorophyta, Cyanophyta and Euglenophyta. Chlorophyta dominated with 11 species, Cyanophyta with 3 species and lastly Euglenophyta with 1 species. The physico-chemical parameters were 24˚C, 26˚C , 5.3, 49.0μS/cm, 24.0mg/L, 20.0mg/L, 25.0mg/L, 46.0NTU, 8.6mg/L for air, water temperature, pH, conductivity, total dissolved solid, total hardness, total alkalinity, turbidity and dissolved oxygen respectively, while those for nutrients were 13.0mg/L, 0.04mg/L and 0.1mg/L for sulphate, phosphate and nitrate respectively. The parameters were below the permissible limit of WHO for drinking water except turbidity and dissolved oxygen which was above the recommended values.
