Composition and Abundance of Zooplankton in Relation to Physico-chemical Factor In Gilgal-Gibe Reservoir,Jimma Southwest Ethiopia

Abstract

The present study aimed to assess the composition and abundance of zooplankton in relation to physico-chemical factors in Gilgel Gibe Reservoir. The zooplankton of Gilgel Gibe Reservoir was sampled at five stations in October concurrently with physico-chemical parameters. The data was analyzed using descriptive statistics, one-way ANOVA, canonical correspondence and biological indices. Conductivity of the reservoir at Asendabo site was significantly higher than at Deneba,Center, Nadi and Yedi sites (p < 0.05). There was significant difference in the mean pH values at Center dam (7.860± 0.399) and (7.68± 0.25) at Deneba site. The mean DO and water temperature of Asendabo site (7.22 ± 1.08mg/L, 25.20 ± 0.700C and varied significantly from the other three sites (p < 0.05). 31 species of zooplankton were identified in the reservoir. The Calanoid and Cyclopoid copepodes were the most dominant species throughout the study period. The diversity index narrowly ranged from 1.88 -2.03 spatially. The abundance of zooplankton wasmaximum at Asendabo and Yedi than other sites. The abundance of cladocerans and calanoid copepodes zooplankton showed spatially significant variation (p < 0.05) and the cyclopoid copepodes exhibited spatially significant difference (p < 0.05). Cyclopid copepodes were the dominant group (31%), followed by calanoid copepodsand cladocera (28% and 25%) and 15% of rotifers respectively.