DIVERSITY OF PLANKTON IN ASEJIRE LAKE, OYO STATE, NIGERIA

GREGORY CHIJIOKE OBINANI
Aquaculture and Fisheries Management, Federal University of Agriculture Abeokuta, Ogun State
October, 2014
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Abstract

In developing countries, lakes being important sources of water supply and fishing are vulnerable to anthropogenic impact, yet knowledge of their trophic state in relation to changes in species diversity and environmental variables are limited. This study is aimed at assessing plankton diversity of Asejire lake by sampling of four stations in the lake located in Oyo state in the south west of Nigeria on the Osun River, about 30kms East of Ibadan between February 2014 and August 2014. Samples were analyzed for water quality parameters and plankton diversity. Essential primary productivity nutrients; nitrates and phosphates showed high values. Present study revealed 36 species of phytoplankton and 45 species of zooplankton. Plankton composition varied and was predominantly made of four families of phytoplankton namely: Bacillarophyceae, Desmidiaceae, Cyanophceae and Chlorophyceae, and three families of zooplankton viz: Protozoa, Rotifera, and miscellaneous invertebrates. Dominant phytoplankton species Melosira (Bacillarophyceae) and zooplankton Volvox colonies (Protozoans) were recorded in high densities throughout the sampling period. The variations in the physico-chemical parameters were high (with exception of pH values which showed no significant difference) and mediated by anthropogenic impacts e.g stochastic input of municipal effluents, dumping of domestic garbage and non-point source input of surface runoff from riparian agro ecosystem. From the study it is proposed that plankton can act as biomarker for water quality assessment in water bodies.