The role of sirenians in aquatic ecosystems is largely a function of their feeding ecology. Sirenians are large herbivorous aquatic mammals that often congregate and, being mammals, have high energetic requirements relative to other marine herbivores. An adult dugong can weigh from 250 to 600 kg¹, while the West Indian and West African manatees both range between 350 and 1,400kg², and the Amazonian manatee from 200 to 480kg³. Consequently, sirenians consume significant amounts of aquatic vegetation. They also display dietary preferences in regard to plant species, individual plants, and parts of plants4,5. Thus dugongs and manatees have the capacity to.