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Journal of Biological Sciences

Year: 2007 | Volume: 7 | Issue: 6 | Page No.: 865-869
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Authors

K.S. Chukwuka

U.N. Uka

Keywords

Research Article

Effect of Water Hyacinth (Eichornia crassippes) Infestation on Zooplankton Populations in Awba Reservoir, Ibadan South-West Nigeria

K.S. Chukwuka and U.N. Uka
The effects of water hyacinth infestation on the distribution, abundance and species composition of zooplankton in Awba reservoir were investigated. Samples were collected in each of the sampling areas (water hyacinth infested and open water) by vertical zooplankton hauls using 64 um bolting silk net. The samples were immediately fixed in 4% formalin for preservation. The species composition of the zooplankton from the sampled areas consisted of 3 taxa, comprising of 6 species of Cladocera (Moina sp., Ceriodaphnia sp., Pleuroxus sp., Diaphanosoma sp., Chydorus sp. and Leydigia sp.) 6 species of Rotifers (Asplanchna sp., Trichocerca, Filinia sp., Polyarthra sp., Brachionus sp. and Lecane sp.) and 3 species of Copepoda (Cycloid copepods, Copepodite nauphii and Calanoid copepods. However, the study showed that the Rotifers had higher numerical abundance in the study areas. Water hyacinth infested area had a total density of 95 individuals/L while open water had 215 individuals/L. The study showed that the density of zooplanktons were significantly lower (p< 0.05) in the infested area. Biotic indices such as Margalef`s and Simpson`s indices were lower in the infested area while Shannon-wiener diversity index was significantly lower (p< 0.05) in the water hyacinth infested area. The result suggests that water hyacinth dense mats affected the numerical abundance of the zooplanktons.
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