Salvinia molesta (native of south-eastern Brazil) is a free floating aquatic fern that has spread to several countries around the globe including Uganda. Under optimum growing conditions, the plant is capable of spreading rapidly where it can have immense environmental, economic and human health impacts. Thick mats of the weed have been recorded in some parts of Lake Kyoga, Uganda where it hinders the abstraction of water, docking and boat take-off, bathing and swimming activities. Therefore this study aimed to determine the extent of S. molesta at selected landing sites in Lake Kyoga and the influence of anthropogenic activities on the weed coverage as well as the effect of physico-chemical parameters of the water on the development of the weed. Quadrats were used to ascertain the coverage of S. molesta while the physico-chemical parameters were determined by standard methods. The results showed significant positive correlation of S. molesta weed coverage with phosphates (PO 4 -P) and negative correlations with pH, dissolved oxygen (DO) and water flow rate. Though statistically insignificant waste sites re- ). Salvinia molesta distribution in Lake Kyoga is linked to nutrient (PO 4 -P) supply, proximity to the shoreline and the associated anthropogenic activities. Hence waste sites, gardens and boat docks enhance S. molesta invasion in Lake Kyoga. Therefore, sources of nutrients (phosphates) into Lake Kyoga that favour the proliferation of S. molesta should be minimized through adequate waste treatment and prohibition of How to cite this paper: Andama, M.,

Lake Kyoga, one of the great African lakes in Uganda is facing an increasing pressure from human activities yet there is limited information on water quality of the lake. Therefore this study determined selected physico-chemical parameters of Lake Kyoga at some landing sites (Kayei, Acholi inn, Waitumba, Masindi port) and anthropogenic activities (boat dock, waste site, garden, fishing). The parameters included temperature, pH, water flow rate, dissolved oxygen (DO), nitrite ( 2 NO − ) and phosphate (PO 4 -P). The American Public Health Association (APHA) and Water Watch Australia protocols, standard meters, Merck's rapid test kits and timing of a float were used to measure the parameters. The results showed that the mean temperature, pH, DO, 2 NO − and PO 4 -P significantly (p < 0.05) varied across the anthropogenic activities. On the other hand, only temperature, pH and flow rate varied significantly (p < 0.05) across the landing sites. Lake Kyoga water flow rates were the fastest at Masindi port (0.031 m/s) and the least in Waitumba (0.021 m/s) governed by river inflow and surface vegetation cover. The mean pH (6.73 -7.15) and DO (10.15 -13.50 mg/l) of the lake at all the study sites were within the Environmental Protection Agency (EPA) standard values of 5.5 -8.5 and ≥9.0 mg/l respectively. These mean pH and DO values reflect more or less neutral waters which are equally well saturated with oxygen at all the landing sites. However, areas close to the waste sites had the least oxygen levels (10.15 mg/l) followed by gardens (11.82 mg/l) while fishing areas were the most saturated with oxygen (13.50 mg/l). On the other hand, temperature (25.06˚C -25.76˚C) est in the waste sites (0.35 mg/l), followed by gardens (0.24 mg/l) and least in the fishing areas (0.12 mg/l). However, phosphates in the form of P 2 O 5 were higher than the EPA standard value (0.5 mg/l) at Kayei (0.55 mg/l) and Acholi inn (0.55 mg/l) landing sites as well as at waste sites (0.80 mg/l) and gardens (0.55 mg/l) pointing to high nutrient (phosphorus) input at these sites. The high concentrations of nitrites in Lake Kyoga at the investigated anthropogenic activities and landing sites plus phosphate amounts close to waste sites and gardens including Kayei and Acholi inn landing sites call for vigilance in protection of Lake Kyoga through optimized planning. Hence, National Environment Management Authority should ensure proper sewage management in Lake Kyoga catchment to avoid discharge of untreated sewage into the lake. The authority should also regulate waste dumping and cultivation around the lake so as to reduce nutrient (phosphorus) enrichment.