Effects of spreading patterns of water hyacinth (Eichhornia crassipes) on zooplankton population in Lake Naivasha, Kenya
Onywere, S. M.
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This study sought to examine the effects of spreading patterns of water hyacinth on zooplankton populations of Lake Naivasha, Kenya. Water hyacinth (Eichhornia crassipes) was introduced into Lake Naivasha basin in 1986 and its presence continues to affect zooplankton population. For species diversity, Shannon-Weiner Diversity Index (H’) and Simpson Diversity Index (D) were applied to the habitats of the 10 sampling sites for the sampling dates (between October 2003 and November 2004). The Simpson Diversity Index (D) of zooplankton was found to be significantly lower (P< 0.005) under water hyacinth mats (D=0.50) than in water hyacinth-free zones (D=0.79). The study appears to suggest that water hyacinth has significantly reduced the abundance and diversity of zooplankton in the lake. It is therefore recommended that critical intervention strategies be undertaken to control further spread of water hyacinth in the lake so as to prevent both ecological and economic losses as a result of biodiversity loss