The nutrient sources include livestock handling areas, garden runoff, cropping and agriculture, erosion of cultivated land, urban sewage outflows and industrial wastewater among others . For the case of Lake Kyoga, gully erosion, wastes from human activities and livestock are the potential sources of nutrients  into the lake The generated wastes in Lake Kyoga catchment are untreated with high levels of pollutants like phosphates and nitrates . These nutrients create favourable conditions for Salvinia molesta infestation of Lake Kyoga. However, there has been inadequate study and management of S. molesta weed on Lake Kyoga as evidenced by the outcry of the people in Lake Kyoga basin from Salvinia infestation with its devastating environmental and socio-economic impacts . Hence an urgent intervention to control the noxious S. molesta weed in Lake Kyoga is required so as to fully use and exploit the resources of the lake. This study therefore determined the proliferation of Salvinia molesta weed at selected landing sites in Lake Kyoga as a result of anthropogenic influences and some physico-chemical parameters that favour the multiplication of S. molesta in Lake Kyoga in a bid to control the weed.

Dense swamps  comprising mainly of extensive mats of Cyperus papyrus L. surround the shores of Lake Kyoga and the numerous tributaries of the lake These wetlands create small bays close to the shorelines of the lake which support the establishment of S. molesta . The lake is surrounded by fishing villages with the people using boats for fishing and inland water transport hence there are several boat landing sites along the shores of the lake. Furthermore, mobile grow systems garbage from peoples’ homes and surrounding hotels are damped near the lake and cultivation is also done close to the lake. Therefore, in order to determine the extent of S. molesta coverage as influenced by the anthropogenic activities , four landing sites on Lake Kyoga namely; Waitumba at geographical coordinates , Masindi port , Acholi inn  and Kayei  were purposively selected for the study. The sampling points at Waitumba, Masindi port and Acholi inn landing sites were close to the shoreline of the lake while the sampling points at Kayei landing site were slightly offshore . The weed coverage was determined at or near waste sites , garden, boat dock and fishing areas in the landing sites. The coverage of S. molesta was determined using the quadrat method Six plots  each measuring 20 m by 20 m  were randomly set at or near the identified anthropogenic activities  in the landing sites . Four boats were arranged in the water at a distance of 20 m from one another to form the square plot  at each of the sampling sites.

Various shapes/figures  formed by the S. molesta mat on the surface of the water in the 400 m2 area were established and their dimensions measured using a tape measure. The area of each shape/figure  of S. molesta mat in the 400 m2 area was then calculated and the total area of the weed coverage in the 400 m2 area obtained by summing up the respective areas of the mats. Water samples were also collected and on-site measurements taken around the S. molesta mats in the study sites to determine the physico-chemical parameters that favour the multiplication of S. molesta or are compromised by its spread . Field work was done in one sampling period starting from December, 2015 to January, 2016When the authors investigated the growth rates of the weed in pH values between 5 and 8, increased biomass was obtained at pH of 6 and 6.5 compared to biomass at higher pH ranges. Furthermore, solid mats of S. molesta hinder gas exchange and often times build up carbon dioxide levels in the water column causing acidification of the waterway hence reduction of pH . The above findings justify the negative correlation of S. molesta coverage with pH in the present study. The thick S. molesta mats also lower the concentration of dissolved oxygen in water column  hence explaining the negative correlation of dissolved oxygen with S. molesta coverage. The negative correlation of S. molesta coverage with water flow rate obtained in this study is expected since S. molesta grows best in stagnant or slowly moving waters .

Furthermore, flushing usually moves infestations of S. molesta according to van Oosterhout . The lower coverage of S. molesta in Kayei and higher coverage in the other landing sites  can be respectively attributed to the offshore and shoreline locations of the sampling areas at the landing sites . According to Aloo et al. , aquatic weeds thrive most along the shores of water bodies. In addition, CABI  reported that S. molesta prefers small bays and inlets of dissected shorelines with less wave action. Furthermore, Wanda et al.  found out that S. molesta was well established along most of the shoreline in the central and western zones of Lake Kyoga. In addition to protection of S. molesta from wave action, the shoreline areas are also richer in nutrients than the offshore locations due to their lower depths.