[Salvinia auriculata] (water fern, Kariba weed, African pyle) is notorious for its ability to colonize large areas of water in a short amount of time. When plants cover a water surface, they cause more water to be lost by evapotranspiration than would be lost by evaporation from an open water surface of the same size (this excess water loss is always likely to occur whenever floating or emergent vegetation is present on a waterbody). The problem is more serious in areas where water is scarce or when the contents of a reservoir are not quickly replaced. Permanent weed mats can interfere with water transport and pose a hazard to navigation.
The explosive growth of [Salvinia auriculata] has caused difficulties in North America, Africa, Asia and Australasia for the management of man-made lakes, canals and irrigation schemes in tropical areas. On Lake Kariba (on the Zambia, Zimbabwe border), large boats are unable to penetrate into certain marginal areas of the lake because of the presence of [Salvinia auriculata] weed mats.