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|  Corals themselves are found throughout all the world's oceans, at all depths. Reef building corals, hermatypic corals, are almost entirely found in warm, shallow, clear waters between the latitudes of 30N and 30S. Coral reefs are fragile ecosystems made up of a variety of different coral species. Each individual coral is made up of tiny organisms called polyps. These polyps contain symbiotic zooanthellae that rely on clear warm water for photosynthesis and survival. The coral relies on food from both the zooanthellae and food caught from the ambient water to build skeletons of calcium carbonate. It is the skeletons of corals that are critical in coral reef formation.The Yaebishi is an extensive coral table that appears above the surface of the sea for a few days a year around March 3 by the lunar calendar, known as Sanitsu. It is located near Miyako Island, Japan. Photo courtesy of Topham, UNEP | | |  Coral reefs are, even in ideal conditions, very very slow growing. Some of the massive coral structures, like the one shown below, will only grow a few millimetres a year. Even the faster growing branching corals grow just 150 millimetres per year.An elkhorn coral colony. Photographer: Paige Gill. Photo courtesy of: Florida Keys National Marine Sanctuary and NOAA. | | | | Corals are vulnerable to any activity that effects the water they live in. The range of activities taking place around coral reefs covers the whole scope of marine activities. Careless scuba divers, shipping pollution, land based sources of pollution, natural disasters, and human initiated disasters alike, all effect the ability of corals to survive. The immense diversity of marine life that live on and around coral reefs will also be lost should the corals die. | | | | |
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| | | Title | Assembly of Landsat 7 Data for Coral Reef Mapping
( MULTIMEDIA FILE )
| | Author(s) / Editor(s) |  Earth Sciences and Image Analysis, NASA-Johnson Space Center | | Description | The first challenge for global coral reef mapping with Landsat 7 is in getting global data that is not obscured by cloud cover. Global data acquisition for coral reef mapping was initiated through the Landsat 7 Long Term Acquisition Plan (Gasch et al. 2000). Once the instrument began acquiring data over coral reefs, it took several years to get the needed acquisitions because of tropical cloud cover, and to find ways to purchase or trade for the over 1000 scenes necessary to complete the global coverage. The data assembly was led by scientists in the Institute for Marine Remote Sensing at the University of South Florida. A number of groups within NASA provided Landsat scenes, and collaborators in mapping projects around the world shared their data in order to assemble the most complete possible archive of Landsat 7 data. The archive and online data interface has been developed by the SeaWiFS Project at Goddard Spaceflight Center. | | Keywords | CORAL REEF; LANDSAT | |
| Content Language(s) | English | |
| Web Address | http://seawifs.gsfc.nasa.gov/cgi/landsat.pl | |
| Type of Multimedia File | Map: Online Dynamic Map | |
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| Additional Links | http://eol.jsc.nasa.gov/reefs/default.htm | |
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| Related to Topics | Coral Reef Mapping
(69131); Coral Reefs
(12725); Reefs at Risk
(2575); Coral Reefs
(2549); Corals
(19381) | | | |
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979 Topics - 5229 Related Knowledge - 11257 Members - 47 Editors |
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