GEF-World Bank Coral Reef Targeted Research Program

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Ben Sherman


NOAA Coral Bleaching Monitoring Network Now Global

October 9th, 2008

NOAA's Coral Reef Watch bleaching monitoring network has expanded its network of "virtual stations" from 24 to 190 locations worldwide. These stations warn coral reef managers when there is an elevated risk of coral bleaching, based on temperature data from NOAA’s environmental satellites. 

The satellite alert system provides approximately two weeks’ advance warning before bleaching occurs, giving reef managers time to respond. The expansion was made possible, in part, through the GEF-World Bank Coral Reef Targeted Research Program. Additional support comes from the NOAA Coral Reef Conservation Program.

"Bleaching is a major threat to the health of endangered coral reef ecosystems across the earth," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. "The expansion of this critical climate monitoring tool will help us better track, understand and mitigate the impacts of warming waters that contribute to the bleaching damage."

Coral Reef Watch monitors thermal stress at selected reef sites, known as virtual stations, and issues email condition reports. NOAA monitors some sites with instruments in the water that provide information for about a dozen reefs worldwide. The expanded virtual station network uses satellite technology to remotely monitor the water temperature, thermal stress, and wind speed at reefs, without the cost and difficulty of deploying buoys.

Sea surface temperature data used by Coral Reef Watch comes from NOAA’s Polar-orbiting Operational Environmental Satellites that provide daily coverage of the earth’s surface.  Continuous monitoring of sea surface temperature at global scales provides researchers and stakeholders with tools to understand and better manage the complex interactions leading to coral bleaching.

Reef conditions are assessed twice each week, so subscribers have up-to-date information about bleaching risk. The alerts will now cover 190 coral reefs in the Florida Keys, Caribbean, Gulf of Mexico, Indian Ocean, Coral Triangle, Australia’s Great Barrier Reef, Hawaii, and the Pacific Ocean.  Products are available from the Coral Reef Watch experimental products webpage:

“We are excited to bring these tools to a wider number of users. Our virtual stations have been very popular with reef managers who use them to monitor temperatures at their reefs” said Mark Eakin, Ph.D., coordinator of NOAA’s Coral Reef Watch. “These are a great addition to our bleaching forecasts that address large regions of the ocean.”

The ocean's temperature is increasing due to climate change. Corals are stressed when water temperature stays two degrees Fahrenheit above the summertime average for a week or more, especially when there are no winds to mix surface waters and provide relief from the strong tropical sun. Stressed corals expel the algae that live in their tissues, exposing the white skeleton underneath. Corals typically recover from mild bleaching, gradually recovering their color by repopulating their algae. However, if the bleaching is severe or prolonged, individual polyps or whole colonies will die.

The ability to predict coral bleaching events and provide advance warning is critically important to sustaining healthy reefs. When coral reef managers and reef users are alerted, they can mobilize monitoring efforts, develop response strategies, and educate reef users and the public on coral bleaching and possible effects on reef resources.

The virtual stations are operated by scientists in NOAA’s Coral Reef Watch in Silver Spring, Md.

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