NOAA 2000-520
Contact: Jana Goldman


Researchers studying reef habitats will have a new early warning monitoring system to alert them of episodes of coral reef bleaching. Coral Reef Watch, a new NOAA program, will develop a long-term coral reef monitoring system with the ability to predict coral bleaching episodes in all major U.S. coral reef areas.

The project is a collaborative effort among NOAA's Atlantic Oceanographic and Meteorological Laboratory in Miami, Fla., the National Environmental Satellite, Data, and Information Service, and the National Undersea Research Program.

Reef habitats in the Atlantic, Pacific, Gulf of Mexico, and Caribbean are increasingly threatened by environmental changes and human interaction. Despite their importance to fisheries, tourism, and coastal protection, there is still much to learn about these delicate ecosystems.

"Bleaching" refers to the loss of color in coral. Coral bleaching occurs as coral tissue expels its zooxanthellae, a symbiotic algae that resides in the structure of the coral and is essential to its survival. Bleaching can be caused by a variety of events, such as change in water temperature or a change in nutrient composition.

"We need long-term in-situ monitoring of reefs, which is essential to understanding the increasing stresses on these unique but fragile ecosystems," said Dr. Jim Hendee of the Atlantic Oceanographic and Meteorological Laboratory.

The first step is the installation of meteorological and oceanographic monitoring stations at key sites in the Bahamas and the U.S. Virgin Islands. Near real-time data from these stations will be used to validate the satellite-monitored high sea temperature ("HotSpot") data, as well as analyze conditions that may lead to coral bleaching. Scientists will also use an artificial intelligence technique developed at the Miami laboratory – the Coral Reef Early Warning System or CREWS.

CREWS inspects data and models the combined effect of environmental conditions such as sea temperature, salinity, tides, and ultraviolet light. When stressful conditions are detected, an alert is automatically sent to researchers and sanctuary managers, as well as posted on a Web site:

"The use of CREWS, together with NOAA's ‘HotSpot' data and biological monitoring data, helps us keep our fingers on the pulse of coral reefs globally and also to gauge the effect of human influence," said Hendee.

CREWS successfully predicted coral bleaching episodes in the Florida Keys National Marine Sanctuary in 1998 and on the Great Barrier Reef in January 2000. These successes lead coral reef researchers to believe that it is feasible to develop an early warning system that will provide one to two weeks advanced notice of bleaching episodes and related habitat/ecosystem responses with an at least 90 percent accuracy.

While researchers know of no way to reverse or halt the bleaching once it begins, the advance notice will allow them to be present at the beginning of the bleaching and then be able to pass on this reef health-threatening information to reef managers. Reef managers would then be in a position to react quickly to help reduce stressful impacts from other factors in ways that had previously been impossible. This coupled with the modeling of the environmental factors affecting bleaching will give scientists a better understanding of what causes the event.

NOAA's mission is to describe and predict changes in the earth's environment and to conserve and manage wisely the nation's coastal and marine resources.

For more information about NOAA's coral reef programs, visit: