NOAA delivers early warning of coral bleaching

A new marine program from NOAA will help researchers track and predict coral bleaching in areas such as the Florida Keys, pictured here

By Environmental News Network staff

Coral bleaching sucks the life out of coral reefs, taking away their vibrant color and often rendering them useless in the marine ecosystem.

But a new program developed by the National Oceanic and Atmospheric Administration will soon arm researchers with an early-warning monitoring system to alert them to bleaching episodes.

NOAA's Coral Reef Watch is a long-term monitoring system with the ability to predict bleaching episodes for all major coral reefs in the United States. The first monitoring system is scheduled for installation next month in the Bahamas.

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

Reef habitat in U.S. waters — the Atlantic and Pacific Oceans, Gulf of Mexico and Caribbean Sea — as well as around the world are extremely sensitive to environmental changes and human interaction.

Coral reefs thrive in warm water with moderate, stable salinity and a small amount of nutrients or sediment. They are widely considered a barometer of global warming.

Coral reef bleaching occurs from the death of zooxanthellae, a symbiotic algae that lives in the structure of the coral and is essential to its survival.

Bleaching can be caused by several events. Global warming, the El Niño phenomenon and changes in ocean circulation are prime suspects. Increased ultraviolet radiation due to thinning of the protective ozone layer may also be a cause.

"It's a scary picture from what we've seen. Over the last 15 years, the Northern Hemisphere tropical temperatures have gone up by one half degree (Fahrenheit)," said Alan Strong of NESDIS. "The problem is that if we get to the point where we have another few episodes (of bleaching) like we did a few years ago, simply being aware might help for a while, but when the temperatures get to be too high for too long, we're limited to what we can do."

NOAA's first step in monitoring coral reefs and detecting bleaching events is to install meteorological and oceanographic monitoring stations at 20 key sites. The first sites will be in the Bahamas and the U.S. Virgin Islands. Near real-time data from these ocean towers will be used to validate satellite-monitored, high-sea temperature data, called "hot spot" data.

In addition, scientists will use an artificial intelligence technique dubbed the Coral Reef Early Warning System, or CREWS.

Coral bleaching is irreversible once it begins

CREWS monitors data and models the combined effect of environmental conditions such as sea temperature, salinity, tides and ultraviolet light on coral reefs. When stressful conditions are detected, an alert is automatically sent to researchers and sanctuary managers.

"The use of CREWS, together with NOAA's hot spot 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 advance notice of bleaching episodes and habitat responses with 90 percent accuracy or better.

While researchers know of no way to reverse or halt coral bleaching once it begins, the advance notice will allow them to alert reef managers in advance of bleaching events.

Copyright 2000, Environmental News Network, All Rights Reserved

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NOAA's Coral Reef Watch
Florida Keys National Marine Sanctuary
Great Barrier Reef
NOAA's Coral Reef site
Atlantic Oceanographic and Meteorological Laboratory
National Environmental Satellite, Data, and Information Service
National Undersea Research Program
Larry Benvenuti

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