An Observation on Diatom Species Composition in the Kenyan waters of Lake Victoria

Abstract

Planktonic diatoms were investigated in the Kenyan waters of Lake Victoria in September 1997. A total 82 diatom taxa were recorded. Among the centrales, Aulacoseira was the most diversified genera followed by Cyclotella, and, among the pinnates, Nitzschia and Navicula were the most diversified. Diatom abundance ranged from 2.51 x 105 to 5.42 x 105 frustules l-1 in the Nyanza Gulf and from 1.58 x 105 to 8.61 x 105 frustules l-1 in the open lake. Nitzschia acicularis and N. lacustris were the most dominant in the open lake and they were prevalent in most parts of the lake. N. gracilis and Cyclotella radiosa were also important in the open lake. Aulacoseira nyassensis var. victoriae, Navicula digitoradiata, Nitzschia palea, Cyclotella ocellata and C. meneghiniana predominated in the Nyanza Gulf. The spatial patterns indicate recent changes in species composition and abundance of dominant taxa. Species richness, diversity and equitability were higher inshore than offshore. Diversity was related to Secchi transparency, conductivity and concentration of silicate.