Author(s): Guto Kerubo Carolyne, Njiru Murithi James,Getabu Albert & Gichana Moraa Zipporah
The water level increased in the Lake Naivasha leading to its merging with Lake Oloiden forming an estuary. A study was done monthly, for one year in the Lakes Naivasha and Oloiden: with an objective to investigate the variation in water quality variables and their effect on zooplankton along a salinity gradient in the Lakes Oloiden and Naivasha. Water quality variables were measured in situ and the zooplankton sampled in each of the sites. The Lake Oloiden had higher total dissolved solids (0.41±0.085 mg/l), salinity (0.310±0.065 ppt), temperature (21.54±2.19 o C)), conductivity (0.58±0.1 μS/m) and pH (8.51±0.3) compared to Lake Naivasha. Temperature, pH, conductivity, total dissolved solids were lower than previous findings while dissolved oxygen was similar. Brachionidae had the highest number of species, however its density was lower as compared to Daphnidae, Sisidae and Cyclopoidae. Cyclopoidae had a negative correlation with the conductivity and total dissolved solids while salinity's correlation was positive ain Lake Naivasha: its correlation was positive with conductivity and total dissolved solids and negative with salinity and dissolved oxygen in Lake Oloiden. There was variation in the water quality variables and all families had associations with water quality variables in Lake Oloiden while only Lake Naivasha’s Cyclopoidae had. Further research should be done on zooplankton variation with depth post water level rise.