Lakes Naivasha and Oloiden merged due to the rise in the water level in the former. A study was conducted for one year in an endeavor to investigate spatial temporal variation of select physical and chemical parameters between the Lakes Naivasha and Oloiden. The water quality was sampled monthly in each site in Lake Oloiden and Lake Naivasha by measuring some water quality variables insitu and collection of water samples for laboratory analysis. The water depth and the secchi depth were measured in each site while some physical-chemical parameters were measured insitu using a YSI Multiparameter probe. Nutrients (phosphates and nitrates), total suspended solids, chlorophyll-a analysis was done in the laboratory using the standard methods. The lakes depth and the secchi depth have increased in both lakes. The phosphates varied site-wise and chlorophyll-a concentration has decreased post water level rise. Lake Oloiden’s temperature, pH, conductivity and salinity were higher as compared to the Lake Naivasha’s. The principal component analysis showed 4 principal components (PCA-1 to PCA-4) which accounted for 94.7% of the variation. PCA-1 and PCA-2 biplots suggested: a link between chlorophyll-a to orthophosphates, nitrates, phosphates (Oloiden ST1 and ST2). Oseria and Korongo sites were closely associated with the secchi depth, lake depth, pH and salinity. 4 distinct clusters were noted: Crescent, Malewa, midsection (Midlake, Korongo, Oseria) and Lake Oloiden (Oloiden ST1 and ST2). The increase in the water level and the merging of saline and fresh water ecosystem led to the creation of a salinity gradient; an area where abiotic and biotic processes are non-linear. There was spatial temporal variation in water quality among the sites. Analysis of variance in water quality in the Lake Naivasha and Lake Oloiden provided an insight about water quality status: associations between water quality variables and sites may aid in effective management decisions.
06 July 2023
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