Coral Reef AnimationWashington, March 5, 1999 — NOAA scientists are working with two Australian groups to improve coral reef monitoring and help promote early warnings of future bleaching events. The scientists are making extensive use of satellites and computerized expert systems.

The reefs are extremely important and fragile ecosystems. They thrive as long as temperatures remain at or below certain temperatures for a given site. An increase of one or two degrees above the usual maximum temperatures can be deadly to these animals. The temperature range for corals to thrive varies from site to site by only a few degrees. While many corals normally recover from short bleaching events, long-term or frequent bleaching may severely weaken the corals, leaving them more vulnerable to disease, damage or death.

Current NOAA satellite and expert system observations indicate that temperature conditions around the Great Barrier Reef have been close to the bleaching threshold temperatures since mid-January. But, scientists from the Australian Institute of Marine Sciences (AIMS), the Great Barrier Reef Marine Park Authority (GBRMPA), and reef users have not reported any major bleaching so far.

Al Strong of NOAA's National Environmental Satellite, Data, and Information Service uses satellites to measure sea surface temperatures and identify HotSpots, warmer- than-usual areas in the oceans where bleaching could take place. Strong has been able to predict coral reef bleaching events over large ocean areas since 1997.

Part of the collaboration with the Australians aims to see how precisely satellites can predict the location of bleaching. Terry Done, AIMS senior principal research scientist, said, "The strength of the NOAA HotSpots is in locating the broad general areas where one might look for bleaching. Our teams are seeing great patchiness in bleaching within these broad areas, so with NOAA, we are going to see how far we can push the satellite technology to explain what we actually see on the reefs."

Jim Hendee of NOAA's Atlantic Oceanographic and Meteorological Laboratory in Miami, Fla., has developed a suite of computerized "expert systems" to automatically
scan weather data from U.S. and Australian weather stations. One system provides an alert via e-mail or the World Wide Web when conditions are thought to be conducive to coral bleaching.

"Coral reefs -- the rainforests of the sea -- are some of the oldest and most biologically diverse ecosystems on earth," NOAA Administrator D. James Baker said. Baker will address attendees at the second Coral Reef Task Force meeting on Maui, Hawaii, later this week. "Important assets to local and national economies, they produce fisheries for food, materials for new medicines, and income from tourism and recreation, as well as protect coastal communities from storms."

Coral bleaching can be a sign that the coral is being stressed by a number of factors, including pollution, sedimentation, high light levels, reduced water levels, or changes in salinity. Increases in water temperature of one degree or more for one month above the summer maximum often result in extensive coral bleaching, making coral reefs under these HotSpots prime candidates for bleaching events.

About 50 countries have reported coral bleaching to some degree in their reefs since 1997, Strong reports. He is among several authors who are publishing these unprecedented results, primarily over the Eastern Hemisphere coral reefs, in an upcoming issue of the scientific journal Ambio. During the El Niño of 1982-83, large areas of coral reefs around the world, including the Great Barrier Reef, were severely damaged by high water temperatures associated with coral bleaching.

Bleaching and other problems facing coral reefs were discussed at the first meeting of the Coral Reef Task Force in Key Biscayne, Fla., last October. The Coral Reef Task Force was created by an executive order signed June 11, 1998, by President Clinton.

Editor's Note: Maps showing twice-weekly distributions of HotSpots are available at:

Movie/animations are posted at: http://manati.wwb.noaa.gov/orad

Maps showing the annual distribution of bleaching from 1969 through 1997 are posted at: http://www.fas.harvard.edu/~goreau

For information on NOAA's Coral Health and Monitoring Program, go to:

For more information on NOAA's Coral Reef Initiative, please visit:


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