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NASA gauging coral reef health through satellite imagery

11 October 2006: A research programme involving NASA satellites, the University of South Florida and other agencies is looking at how surface conditions affect the bleaching of the Florida Keys coral reef. Conducting research on the Florida Keys coral reef usually requires a boat and scuba gear. But the new project tries looking from a different vantage point – 438 miles above the Earth.

Some areas of the Keys reef appear more resilient to bleaching than others. Information gleaned from NASA’s Terra and Aqua satellites may help show why. Corals turn white when tiny algae that live inside them die. Bleaching is a symptom of coral stress, which can be caused by high water temperatures, other environmental stresses, or disease.

The satellite monitoring conducted in August and September was part of the new Florida Reef Resiliency Programme, funded by the state, The Nature Conservacy and other agencies.

“Increasingly, sophisticated technology allows us to better target field observations, improving our ability to monitor the health of coral reefs in the Florida Keys National Marine Sanctuary,” Sanctuary Information Officer Cheva Heck said.

The monitoring focused on nearly 175 sites stretching from the Dry Tortugas to the northern limits of the reef tract off Central Florida. The Keys have the nation’s heaviest concentrations of coral growth.

At sites for the study, “scuba divers recorded the number and species of coral and the extent of bleaching,” according to a NASA account. “Data from the moderate-resolution Imaging Spectroradiometer aboard the Terra and Aqua satellites gave accurate, up-to-date information on sea-surface temperatures to identify areas vulnerable to bleaching. The data was also used to measure the cumulative heat buildup over several weeks, shown to be particularly important to the health of reefs.”

Coral reefs can be damaged by changing environmental conditions, storms, coastal development and pollution, said Christopher Moses, a University of South Florida researcher. “There appear to be more stressors than in the past. This is a major concern as bleaching events are becoming more common and severe,” Moses told NASA. “The Florida reef tract is considered by some to be a modest success story as many of the corals persist despite the many stressors including impacts from human coastal development and recreation.”

Findings from each sampling site will be analyzed over the next several months as scientists seek to identify factors that help coral survive. “The sanctuary, a partner in the Florida Reef Resilience Programme, looks to this extensive satellite and in water assessment as a major step toward learning what conditions our reefs need to thrive,” Heck said. Late summer is a common time for coral bleaching as water temperatures hit their peak.

“During the strong El Nino of 1998, about 30 percent of coral off the Florida Keys died after a single mass bleaching,” noted researchers. For more information on the programme, and satellite images, see the NASA Web site, https://www.nasa.gov/centers/goddard/news/topstory/2006/coral_health.html