Phycological Effects of Eutrophication with Fertilizers in Nike Lake, Nigeria

Abstract

Agriculture around Nike lake uses fertilizers. Fertilizers are known to cause eutrophication of water bodies and associated algal blooms whose consequences may be deleterious to the environment and man. We in- vestigated ex situ to assess the effect of the nutrients on the algal flora and show the impact of farm land runoffs on aquatic environment. The lake water was analysed for initial nitrogen, phosphorus and potassium; and algal content using standard methods. The fertilizer sources used by the farmers—NPK (20:10:10 and 15:15:15); urea and poultry drops, were used in the study to enrich the lake water in concentrations of 0.2, 0.4, 0.6, 1.0 and 2.0 g/L in three replicates respectively. A control was set up without the fertilizer sources and the set up was left on a laboratory bench and monitored for 36 days. Cyanobacteria (blue green algae), Chlorophyta (green algae) and Bacillariophyta (diatoms) were encountered and their population increased with time and increase in concentration of fertilizers. The following taxa were encountered—Gloeocapsa, Anabaena, Oscillatoria (blue-green algae); Chlorella, Chlamydomonas, Spirogyra, Closterium, Pediastrum, Ankistrodesmus, Selenastrum, Scenedesmus, Staurastrum (green algae); Pinnularia and Navicula (diatoms) some of which are notable bloom forming species