The dynamics and ecology of exotic tropical species in floating plant mats: Lake Naivasha, Kenya

Abstract

The floating water fem Salvinia molesta has occurred in Lake Naivasha since the early 1960s and during this period has obstructed fishing activities and navigation. In recent years the extent of Salvinia has declined marked1y. Since 1988, a second floating weed, Eichhomia crassipes (water hyacinth), has colonised the lake. Salvinia formed large mats around the edges, bays and lagoons and had very few plant or invertebrate species associated with it. Mats of E. crassipes, however, support a greater abundance and variety of animal and plant species, which shows a relationship with mat size. This seems to have faci1itated plant succession but without a zonation typical of the classic hydroseral sequence for the lake.