From: LARRY KLAES (ljk4_at_msn.com)
Date: Mon Dec 08 2003 - 11:15:14 PST
----- Original Message -----
From: NASANEWS_at_mail.arc.nasa.gov
Sent: Monday, December 08, 2003 12:47 PM
To: ames-releases_at_lists.arc.nasa.gov
Subject: NASA LEARNING TO MONITOR CORAL REEF HEALTH FROM THE SKY
John Bluck Dec. 8, 2003
NASA Ames Research Center, Moffett Field, Calif.
Phone: 650/604-5026 or 650/604-9000
E-Mail: jbluck_at_mail.arc.nasa.gov
RELEASE: 03-101AR
NASA LEARNING TO MONITOR CORAL REEF HEALTH FROM THE SKY
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. 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.
"We moved up from the coral, little by little, to the surface to
learn how light intensity decreases in the water column, which
affects our coral reflected-light readings," Guild said. "There also
will be a layer of atmosphere between the coral, the water and the
sensor when it eventually flies aboard an airplane to survey the
reefs," she added.
"The effects of the atmosphere on light are pretty well known, but
the challenge is to correct for the effects of the layer of water
over the coral," Guild explained. "Instead of taking the top-down
approach, we are going from the bottom up to the airplane, and later
to satellite sensing of coral health," Guild said.
"Ultimately, we plan to fly 'hyperspectral' instruments, containing
many detectors that collect information in the visible light range,"
Guild explained. These 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.
Guild will discuss her group's work at the fall meeting of the
American Geophysical Union on Dec. 9, at 5:45 p.m. PST, in room 3000
of the Moscone Convention Center, San Francisco.
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.
For information about NASA's Earth Science Enterprise on the Internet, visit:
For images on the Internet, visit:
http://amesnews.arc.nasa.gov/releases/2003/03images/coral/coral.html
More information about the coral monitoring project is available at:
http://geo.arc.nasa.gov/sge/coral-health
-end-
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