Parts of the atoll may emerge as islands. Coral reefs provide habitats for a large variety of organisms. These organisms rely on corals as a source of food and shelter. Coral reefs and their associated communities of seagrasses, mangroves and mudflats are sensitive indicators of water quality and the ecological integrity of the ecosystem. They tolerate relatively narrow ranges of temperature, salinity, water clarity, and other chemical and water quality characteristics.
Reefs thus are excellent sentinels of the quality of their environment.
Proper monitoring of reefs can identify changes in water quality or impacts from land-based activities. Monitoring changes in water quality can help local resource managers understand the implications of actions occurring in watersheds that are associated with particular coral communities. These connections will help in development of sound management plans for coral reefs and other coastal and marine resources. Man has had a long association with reefs. They are important fishery and nursery areas, and more recently have proved to be very important economically as tourist attractions.