NASA to monitor coral reef health from the sky

NASA to monitor coral reef health from the sky

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Coral reef health may be accurately estimated from sensors on airplanes and satellites in the future, according to a NASA scientist who is the principal investigator in a collaborative project to develop a method to remotely sense coral health.

Sometimes called the “bellwether of the seas,” coral reefs can give first indications of marine ecosystem health. “Scientists can use coral health as a sensitive indicator of the health of the marine environment,” said Liane Guild, a scientist at NASA Ames Research Center, Moffett Field, Calif.

“We’re looking into how you could remotely detect coral reef health using aircraft with visible light sensors,” Guild said. “First, we have to look at the coral close up, underwater, to see what spectral reflectance the sensor picks up from diseased, stressed and healthy coral.”

One of the first steps her team took to develop aerial coral monitoring was to take undersea light-reflectance readings of elkhorn coral with a handheld spectroradiometer, or light meter. A team of four scuba divers, from the Universities of Miami, South Florida and Puerto Rico, helped Guild take the first readings at varying depths in summer 2002 near Andros Island, Bahamas, with assistance from the U.S. Navy Atlantic Undersea Test and Evaluation Center. A spectroradiometer measures the amount of ultraviolet, visible and infrared light reflected from an object, and is similar to sensors aboard remote-sensing airplanes and satellites.

Instruments will provide the most useful information about coral-reef community health from above the sea, according to Guild. The team’s research emphasis is on Acropora palmata, or elkhorn coral, a major reef-building coral. It is prevalent in the study area, but is suffering from “white band disease.” Elkhorn coral is on the verge of becoming an endangered species because it has severely declined in many areas of the Caribbean, Guild noted.

The team and engineering scientists from the University of Arizona also are developing a
specialized computer model to analyze coral reflected-light data. The computer model will help scientists better interpret the raw data gathered by aircraft or satellites.

The research is funded by NASA’s Earth Science Enterprise, which is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space.