ABSTRACT

The study eutrophication stimulation effect on river Eruvbi phytoplankton was done to observe the growth response of the phytoplankton to different nutrient enrichment. Water samples were collected from the river site as well as phytoplankton samples. The phytoplankton was subjected to microscopic examination. The study involved natural phytoplankton population and introduced algae of (Scenedesums acutus and Chlorella vulgaris). The nutrient concentration used were 2.4mg/L nitrate, 1.2 mg/L phosphate and 2.4 mg/L nitrate + 1.2 mg/L phosphate, growth measurement was done optically using spectrometry at 750nm. The physiochemical composition of the river was also carried out, with some done in situ and others done in the laboratory. The result of the stimulated experiment showed that indigenous phytoplankton growth was best stimulated by nitrate enrichment, while introduced phytoplankton responded better to phosphate enrichment. The phytoplankton composition of river Eruvbi has a low biodiversity and the algae present show the river to be oligotrophic in nature. Some physiochemical parameters such as dissolved solid, total alkalinity, total hardness and turbidity fell within the WHO guidelines for drinking water, while others like dissolved oxygen and pH were above the WHO guidelines for drinking water. It was concluded from the results that river Eruvbi which is oligotrophic as at present will under eutrophication if subjected to nitrate enrichment which will also cause a rapid bloom in the phytoplankton species of the river. Therefore extra care must be taken to prevent the eutrophication of the river.