"Its rubbery vines and leaves formed thick tangles of vegetation that adhered to the river banks and clogged up waterways. It grew fast, faster than men could destroy it. ... to them it was another enemy." So novelist V. S. Naipaul described water hyacinth, an invasive aquatic weed, in A Bend in the River, his 1979 tale of life in a Ugandan town.
Twenty years later, the water hyacinth remains one of the most aggressive invaders on the continent. Now, researchers are getting a clearer picture of why the South American native is flourishing in the world's second-largest lake, Victoria. A satellite image released this month by the International Center for Research in Agroforestry in Nairobi, Kenya, shows three feeder rivers injecting an immense, nutrient-rich plume of sediment far into Lake Victoria, where the weeds now choke most of the shoreline shared by Uganda, Kenya, and Tanzania. Besides making life miserable for fishing boats, the vegetation mats threaten native species. The new plume portrait will help scientists track the nutrients back to their sources and pinpoint which regions should step up tree-planting and other erosion-control measures.
