The Western Indian Ocean: A Wealth of Life-Supporting Ecosystem Goods and Services

The coastal and marine environment of the Western Indian Ocean (WIO) region is one of the least ecologically disturbed in the world. The region is a hot spot of biodiversity hosting over 2,200 species of fish, five species of marine turtles, more than thirty-five marine mammal species, including humpback whales, dolphins, whale sharks and the highly endangered dugong, and the enigmatic coelacanth; a prehistoric fish once thought to be extinct. The region furthermore boasts the longest unfragmented fringing reef in the world, with over 350 species of corals, and a diverse assemblage of coastal forests, mangrove forests and sea grass beds. It is estimated that about 22 per cent of the species found in the WIO region are unique to this region. The ecosystem services provided by this rich marine environment are estimated at over 25 billion US$ per year. At the crossroad between land and sea, the estuarine ecosystems of the region are the gathering point of a number of large river basins, many of which transboundary of nature, and bringing in influence from far away inland. This chapter provides an overview of the key ecological and physical characteristics of the region, setting the background for the deeper analyses presented in the following chapters.