Horizontal differentiation in water chemistry, phytoplankton, zooplankton and macrozoobenthic communities in Lake Kwania

Abstract

AbstractPhytoplankton, zooplankton and macrozoobenthic invertebrates are important elements in the structure and functioning of aquatic systems. There is, however, limited information to aid in understanding the interactions between these organisms and their environment. The three groups were examined along a horizontal water chemistry gradient in Lake Kwania. The lake was subdivided into three zones: west, central and east, similar to what was earlier described for Lake Kyoga. Conductivity, silica and Secchi depth showed significant horizontal differentiation between zones. Conductivity (126.3, 209.2 and 289.1 μS/cm) and silica concentration (1419.9, 3708.0, 9146.3 μg/L) increased from the west to the east zone. The composition, abundance and taxonomic diversity of phytoplankton, zooplankton and macrozoobenthic invertebrates did not show a significant pattern along this gradient. Cyanobacteria dominated by Planktolyngbya limnetica; Copepoda dominated by Tropocyclops tenellus; and Diptera dominated by Chaoborussp, were respectively the most abundant phytoplankton, zooplankton and macrozoobenthos across zones. These results suggest that other factors control these organisms in addition to the lake's water chemistry. It is critical to investigate these factors further to fill knowledge gaps that will aid in the future conservation and management of Lake Kwania, the Kyoga Lakes in general and other Great Lakes.