A COMPARISON OF CHLOROPHYLL-A PATCHINESS IN KIGOMA BAY, LAKE TANGANYIKA AFRICA AND SENECA LAKE, GENEVA NEW YORK

A preliminary investigation in conjunction with the Nyanza Project revealed a possible temporal correlation between chlorophyll-a concentrations and both thermocline depth and wind stress in Lake Tanganyika. Over a period of three weeks, nine sites arranged on three transects extending from the coast to the pelagic, as well as various depths were sampled for chlorophyll-a concentrations. A temperature recording chain measured temperatures to 100 meters deep at an offshore site. As the wind stress increased and the thermocline became shallower connected with internal seiche movement, nutrient rich water was brought closer to the surface, providing more nutrients for phytoplankton and increasing chlorophyll-a values. As the wind decreased the water became more stable, thus decreasing the amount of nutrients brought to the surface and decreasing the available nutrients for plankton use. Secchi disc depths supported this conclusion with the shallowest depths recorded during periods of high winds and high algal concentrations. In this presentation Seneca Lake was chosen as a site for comparison to the African Rift Lakes due to its similar morphology, and differences in climate. Similar sampling techniques were used, and chlorophyll-a values were analyzed at an off shore site at various depths. Results indicate a link between meteorological change, and an increase in nutrients in the epilimnion increasing chlorophyll-a values.