Role of Climate in the Modern Condition of Lake Victoria

Abstract

Comparison of historical and recent climatic data for Lake Victoria, a great lake in the high elevation tropics of East Africa, demonstrates changes in surface temperature, air moisture, atmospheric transparency, and wind shear from conditions 35 years ago. The changes appear to be part of a global change in climate conditions of the high elevation tropics. The physical and ecological conditions of Lake Victoria appear responsive to lake-atmosphere interactions through mechanisms of wind stress and surface heat fluxes. Lake temperatures, mixing regimes, oxygen levels, and primary production have changed in parallel to air temperature, humidity, atmospheric transparency, and wind speeds between about 1960 and the present. Data indicate strong coupling between meteorological components of lake heat balance and both biological and chemical conditions. Many features of the apparent modern eutrophication of Lake Victoria may have been accelerated or exaggerated by the climate effects. The analysis suggests a mechanism for feedback of climate on lake condition which, if general, might provide a modern analog for periodic changes reported in the fossil diatom community of the lake over the past 10 millenia.