The Indian Ocean has particularly narrow continental shelves along this coast, and thus lower biological productivity than many coastal regions. The coast is rich in varieties and numbers of marine life forms, however. Extensive and highly diverse coral reefs fringe its narrow shelves shores. Species-rich mangroves with their commercially important oysters, crabs and mullet abound near river estuaries and along the coasts, particularly those of Mozambique, Tanzania, Kenya and southern Somalia. The region's people are dependent to a significant extent on coastal resources.
Coastal ecosystems are important economically for tourism and recreation.
The list of threats to the environment has changed little since then. A workshop in 1997 listed domestic sewage, solid domestic waste, habitat degradation, agrochemical pollution and industrial waste pollution. The region remains characterized by vulnerable economies, large populations with a high rate of population growth, and areas subject to environmental stress. The important and heavily fished reef zone close to shore is particularly vulnerable to pollution and silting. Oil is a major pollution threat to coastal ecosystems, owing to the heavy use of the tanker route along the East African coast.