Coral bleaching may be one of the greatest threats to the Great Barrier Reef. Coral bleaching is a stress response that often occurs when the surrounding waters become too warm for the corals. In the stressful situation, the corals expel their brownish zooxanthellae and lose their color. Zooxanthellae are unicellular yellow-brown algae that make it possible for the corals to grow and reproduce quickly enough to create reefs. Without the zooxanthellae, the coral cannot obtain sufficient nourishment. If conditions remain difficult, the corals may die. Major coral bleaching incidents on the Great Barrier Reef in 1998 and 2002 led to widespread death of corals in some areas. Researchers in the Barrier reef of Australia are using NASA's resources to help identify troubled coral.
The Great Barrier Reef is located on the eastern coast of Australia. This intricate network of coral formations has an area of about 14,300 square miles, encompassing about 13 percent of the world's total coral reef.
This is a closeup of Herron Island. The narrow channel leading from the marina to the ocean was blasted and dredged decades ago, before the island became a national park. Since then the Australian government has implemented conservation measures. One of the applications of remote sensing data from Ikonos is environmental monitoring, including studies of coral reef health.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0