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This study determined the concentration of oil and grease and inferred its impacts on algae, invertebrates and fish. Water samples were collected in April and September from 2012 to 2018 at the upstream and downstream transects and in the reservoir, and analysed for oil and grease following standard procedures. Environmental compliance was compared to NEMA’s discharge standard of 10 mg/l, and its PAH effluent discharge standard of ≤ 0.1 mg/l. At all sites, average concentrations of oil and grease were below 10 mg/l throughout the sampling period. Out of the 14 data sets for each transect, only 3 along the upstream transect, and 2 at each of the downstream transect and the reservoir were compliant with the effluent discharge standard. Although impacts of oil and grease on aquatic biota were not assessed, their relatively high concentration compared to total Polycyclic Aromatic Hydrocarbon (> 0.1 µg/l) is considered hazardous to most aquatic organisms. The diverse activities around the project area implied that sources of oil and grease were proportionately diverse. Hence, the observed trends may not solely be attributed to the hydropower project. Accordingly, assessment of the various sources of oil and grease and their impact on aquatic biota in the area is recommended.

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Effective conservation requires reliable data and information on the status of biodiversity. The conservation of freshwater biodiversity lags behind terrestrial and marine biodiversity because data and information limitations are greatest in freshwater ecosystems.  Given that freshwater ecosystems are inhabited by disproportionately more species than other ecosystems, paucity of data and information threatens many species and dependent ecosystem services. Data and information on freshwater biodiversity is limited mainly because few freshwater ecosystems are considered for regular monitoring. However, even existing data is scattered and in non-user-friendly formats, limiting accessibility and use. It is desirable to make freshwater biodiversity data and information accessible everywhere so that it attains its full potential in guiding conservation. To increase accessibility to freshwater biodiversity data in Uganda, we present 34 datasets covering three major freshwater taxa: zooplankton, macroinvertebrates, and fish within freshwater ecosystems in the country. The datasets provide occurrence records and corresponding abundance data where applicable for the three major groups. The datasets which are available through the Global Biodiversity Information Facility (GBIF) cover   a long period from 1971-2021 and have a total of 56,104 occurrence records. Of these records, 8,674 records were published in 2022. The data were mobilized from primary biodiversity surveys conducted by scientists at the National Fisheries Resources Research Institute (NaFIRRI) in Uganda. The surveys covered most of the water bodies in the country. The datasets are envisaged to increase accessibility to data for freshwater conservation research, decision making and capacity building. The data has already found use in development of conservation tools and conservation status assessments.

Phytoplankton, 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.