Abstract:
Spatial and seasonal variations of phytoplankton, expressed in terms of species composition, cell density, biovolumes and
biomass, collected at 10 sampling sites in alkaline–saline Lake Nakuru, Kenya, were investigated monthly from March 2004
to Februar y 2005, in relation to selected physical and chemical water quality parameters. A total of eight species, belonging
to five genera and three classes, were recorded. The Cyanophyceae comprised the bulk of the phytoplankton, followed by
Euglenophyceae, while Bacillariophyceae were the least abundant.
Arthrospira fusiformis
was the most dominant species, in
terms of density, among the Cyanophyceae, while
Euglena
spp. and
Navicula elkabs
dominated the Euglenophyceae and
Bacillariophyceae density, respectively. Seasonal variations in phytoplankton species composition, density and biomass
were significant (
P <
0.05) with minimum cell density and biomass occurring during the dr y season, and being maximum
following the end of the two rainy seasons from May to November 2004, suggesting the possible influence of various
environmental factors on the lake. Sampling sites located close to the inlets of inflowing rivers exhibited significantly
(
P <
0.05) higher phytoplankton cell density and biomass than those by the inshore sites. Soluble reactive phosphorus,
ammonia-nitrogen, conductivity and total alkalinity accounted for most of the variations in the cell densities of
phytoplankton species