Zooplankton composition and abundance in Ikere-Gorge, Iseyin, Oyo State, Nigeria

Abstract

This study examines zooplankton composition and abundance in Ikere-Gorge (a man-made dam), Iseyin, Oyo State. Zooplankton samples were collected monthly with plankton net between January 2017 and December 2018. The samples were preserved, analysed and identified with appropriate keys. Thirty-four genera of zooplankton belonging to four groups were identified in Ikere-gorge. The family of Copepoda recorded the highest number of zooplankton, followed by Cladocera, Rotifers and Ostracoda. But, Bosmina spp belonging to Cladocera group has the highest relative abundance of zooplankton population in Ikere-gorge. Alpha diversity varies between 29 and 32 among the sampling sites while beta diversity among the sampling sites was 0.1. Likewise, Dominance D varies between 0.05 and 0.06 while Simpson varies between 0.94 and 0.95. Shannon Weiner index for Site A is 3.16, Site B is 3.10, Site C is 3.18 and Site D is 3.21. Evenness index for site A and C is 0.73, site B is 0.76 and site D is 0.77. This zooplankton provides abundant food material for abundant fish production in Ikere-gorge.