Great Barrier Reef Spatial Scale

         Coral reefs are typically found in tropical and sub-tropical waters due to their inability to thrive in temperatures below 18°C (NOA, 2008). Coral reefs also require very clear, saline water that is between the range of 32 to 42 part per thousand (NOA, 2008). 

This map taken from NOAA shows how coral reefs are typically found between 30° north and 30° south latitude, where tropical and subtropical waters typically occur. The red dots represent major coral reefs in the world.
http://oceanservice.noaa.gov/education/kits/corals/media/supp_coral05a.html

         The Great Barrier Reef is located in North Eastern Australia and is the only natural wonder that can be seen from space (7 Natural Wonders, 2008). The reef consists of 2,900 separate reefs and over 900 islands (7 Natural Wonders, 2008). The Great Barrier Reef Marine Park covers 345,000 square kilometers, which is "five times the size of Tasmania" or larger than the "United Kingdom and Ireland combined" (WWF, 2012). 

This image was taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.  

http://www.universetoday.com/67562/great-barrier-reef-from-space/

This image is from the European Space Agency
http://www.earthweek.com/2010/ew100507/ew100507x.html

Sources:

1. "Corals." NOAA National Ocean Service Education. NOAA, 25 2008. Web. 30 Nov 2012. <http://oceanservice.noaa.gov/education/kits/corals/coral05_distribution.html>.

2. "Great Barrier Reef." The Seven Natural Wonders. Web. 30 Nov 2012. <http://sevennaturalwonders.org/the-original/great-barrier-reef/>.

3. "Great Barrier Reef." WWF Australia. WWF, 2012. Web. 30 Nov 2012. <http://www.wwf.org.au/our_work/saving_the_natural_world/oceans_and_marine/priority_ocean_places/great_barrier_reef/>.