Coral Reefs

Healthy coral reefs sustain local and national economies through fisheries, coastal protection, and tourism. Despite these benefits, it has been estimated that 58 percent of coral reefs globally are threatened by human activities (Bryant et al. 1998). Scientists still lack basic data about the locations, spatial extent, and health of reefs. Major efforts are underway in the U.S. and around the world to improve the mapping information on coral reefs. Astronaut photographs are a unique data source for these efforts because photos of the reefs have been collected for many years, and the images are available in the public domain. Of particular value is the fact that the astronauts took advantage of opportunities when cloud cover was minimal to take the photographs. Astronaut photographs can be used as primary data for maps of the locations of reef crests and as supplemental data for use with other satellite images, especially when it is important to distinguish small clouds from reef areas.
 

Astronaut photographs are being used as base maps in an international compilation of information on coral reefs, known as ReefBase. Images have also been included in a prototype reef data distribution system that uses a global map based on 1.1-km data from the SeaWiFS satellite sensor as a backbone for links to georeferenced reef remote sensing data from a number of different satellites (Robinson et al. 2000b) Investigations comparing the level of detail that can be mapped from an astronaut photograph to that from other satellite data are nearing completion.
 

Astronaut photograph of Bahrain (STS078-748-11 combined with ReefBase data (yellow dot) and World Conservation Monitoring Centre maps of the reef crest (transparent red).

Images of the Tuamotu Archipelago, American Samoa, Malaysia, and the Philippines are targeted for acquisition during the Crew Earth Observations project, to provide additional data for these mapping investigations.

 Urban Areas
 Deltas