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NOAA's New Coral Reef Watch Satellite Bleaching Alerts Aiding Managers

NOAA satellite image of the regions of high thermal stress as of Oct. 25, 2005, from NOAA's Degree Heating Week (DHW) satellite-based product that accumulates high temperature events.Oct. 25, 2005 NOAA reports that a major coral bleaching event is underway in the Caribbean and may result in significant coral death in much of the region. Currently, the bleaching is centered in waters adjacent to the U.S. Virgin Islands. Reports of bleaching have come in from the Florida Keys and Texas' Flower Garden Banks in the north, to Tobago and Barbados in the southern Antilles, to Panama and Costa Rica in the west. (Click NOAA satellite image for larger view of the regions of high thermal stress as of Oct. 25, 2005, from NOAA's Degree Heating Week (DHW) satellite-based product that accumulates high temperature events. Please credit “NOAA.”)

Warnings of the onset of this event were first reported by the NOAA Coral Reef Watch Satellite Bleaching Alert monitoring system. Bleaching was first seen in late August in the Florida Keys and has now spread throughout much of the eastern Caribbean.

Coral bleaching is associated with a variety of stresses, including increased sea surface temperatures. This causes the coral to expel symbiotic micro-algae living in their tissues—algae that provide corals with food. Losing their algae leaves coral tissues devoid of color, and thus appearing to be bleached. Prolonged coral bleaching (over a week) can lead to coral death and the subsequent loss of coral reef habitats for a range of marine life.

"NOAA's Coral Reef Watch program has really shown its value," notes Al Strong, NOAA Coral Reef Watch coordinator for satellite monitoring. "When combined with observations in the field, it has enabled state and local officials and dive operators to better track bleaching events and use this information to lessen human stress on the reef during this critical time."

Since early October, NOAA has issued Coral Reef Watch bleaching alerts for both Puerto Rico and the U.S. Virgin Islands, where thermal stress is at record levels. Thermal stress has reached Degree Heating Week (DHWs) values of over 15 at some locations. Each DHW represents one week of temperatures 1 degree Celsius above the maximum highest monthly average. Accumulated over three months, DHWs above four are virtually always accompanied by considerable bleaching, whereas levels above eight are believed to present increased coral mortality and inability to recover.

According to Puerto Rican scientists, bleaching is both wide spread and intense with colonies representing 42 species completely white in many reefs. Surveys show 85 to 95 percent of coral colonies were bleached in some reef areas. Reefs in Grenada also are bleached with close to 70 percent of colonies suffering impact to some degree.

Drew Harvell of Cornell University, chair of the World Bank/GEF Coral Disease Working Group, praised the value of the bleaching alerts. "All the notice that NOAA's alerts have given us really allowed us to mobilize a team of scientists to do surveys at sites throughout the Caribbean."

NOAA's Coral Reef Watch Satellite Bleaching Alert system automatically monitors for the thermal stress that gives rise to coral bleaching. Currently, the alert messages are available for 24 shallow coral reefs ecosystems around the world. Through collaborative efforts with the World Bank and Global Environment Facility, NOAA will expand these sites over the next several years to cover 24 selected regional sites in the Caribbean, 24 sites around Australia, 24 sites in Southeast Asia and 24 sites in the western Indian Ocean basin.

"The ability of NOAA's new Coral Reef Watch Satellite Bleaching Alert to provide advance warnings is critically important," said Tim Keeney, deputy assistant secretary of commerce for oceans and atmosphere and co-chair of the United States Coral Reef Task Force that will be meeting November 5-7 in Palau. "By alerting coral reef managers and reef users, it allows them to mobilize monitoring efforts, develop response strategies, and educate reef users and the public on coral bleaching and possible impacts on reef resources. This is a significant step forward in coral reef ecosystem management."

The new Coral Reef Bleaching Alerts are a good example of the benefits that can be derived from an Integrated Ocean Observing System, an effort in which NOAA is taking a leadership development role.

NOAA, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation's coastal and marine resources.

Relevant Web Sites
NOAA Coral Reef Watch

NOAA Coral Reef Conservation Program

NOAA Coral Reef Information System (CoRIS)

Media Contact:
Ben Sherman, NOAA Ocean Service, (301) 713-3066, or John Leslie, NOAA Satellite and Information Service, (301) 457-5005