Diel zooplankton samples were obtained at a 4-m-deep central station on two sampling occasions in January and February, 2010 in Lake Baringo. Sampling was done at l m interval every four hours for 24 h from 8：00 am t...Diel zooplankton samples were obtained at a 4-m-deep central station on two sampling occasions in January and February, 2010 in Lake Baringo. Sampling was done at l m interval every four hours for 24 h from 8：00 am to 04：00 am. Ten litres of lake water was collected by a Van Dorn sampler and sieved through a 50 μm mesh sieve and organisms in the entire sample counted. Concurrently, physico-chemical factors including temperature, pH, conductivity and dissolved oxygen were measured at the same depths in situ. In both sampling months, the temperatures were higher during the day when stratification was observed just below the l m depth. This was, however, broken by diurnal winds in the evenings. PH and dissolved oxygen values followed the same trend but conductivity was generally uniform. In contrast to what has been observed in clear water lakes, the densities of Lake Baringo zooplankton were generally higher at the surface waters during the day while during the night the organisms were distributed throughout the lake column, a phenomenon which could be attributed to the high waters turbidity. The Proximity of zooplankton to the euphotic zone during the day provides them with feeding opportunities on phytoplankton.展开更多
文摘Diel zooplankton samples were obtained at a 4-m-deep central station on two sampling occasions in January and February, 2010 in Lake Baringo. Sampling was done at l m interval every four hours for 24 h from 8：00 am to 04：00 am. Ten litres of lake water was collected by a Van Dorn sampler and sieved through a 50 μm mesh sieve and organisms in the entire sample counted. Concurrently, physico-chemical factors including temperature, pH, conductivity and dissolved oxygen were measured at the same depths in situ. In both sampling months, the temperatures were higher during the day when stratification was observed just below the l m depth. This was, however, broken by diurnal winds in the evenings. PH and dissolved oxygen values followed the same trend but conductivity was generally uniform. In contrast to what has been observed in clear water lakes, the densities of Lake Baringo zooplankton were generally higher at the surface waters during the day while during the night the organisms were distributed throughout the lake column, a phenomenon which could be attributed to the high waters turbidity. The Proximity of zooplankton to the euphotic zone during the day provides them with feeding opportunities on phytoplankton.
