Influence of spatio-temporal variations in precipitation and temperature on the productivity of Eastern Lake Kyoga, Uganda

Abstract

Spatio-temporal variations in precipitation and temperature affect productivity in aquatic systems, mainly through nutrient dynamics. Shallow lakes are more vulnerable to spatio-temporal variations, yet they are an important resource for biodiversity conservation, water supply and fisheries. The eastern arm of Lake Kyoga experiences two dry and two wet seasons annually, yet there is no information on how they affect its productivity. This study, therefore, focused on determining how spatio-temporal variations in temperature and precipitation influence production using chlorophyll-a (Chl-a) as a proxy indicator parameter. Seventeen sampling sites were established for data collection during both dry and wet seasons. Fifteen physico-chemical and biological parameters like total suspended solids (TSS), total phosphorus (TP), and chlorophyll-a were used for assessment. Thirteen of the 15 parameters had increased concentrations during the dry season, with only TSS and water temperature increasing during the wet season. Chlorophyll-a showed significant (p = 0.007) spatio-temporal variations between seasons. It significantly correlated with nitrate (r = 0.964), SRSi (r = 0.901), conductivity (r = 0.970) and pH (r = 0.936) during the dry season. Spatio-temporal variations influence nutrient dynamics, and therefore productivity in Lake Kyoga. These results are critical and should guide the water managers, decision, and policy-makers to develop appropriate mitigation approaches against impacts of spartio-temporal variations on the productivity of Lake Kyoga and its ecosystem.