User:Laujohnson

Coral Reefs Coral reefs are very important ecosystems in our oceans. They are found in tropical areas that have clear, warm water. Coral reefs are formed by polyps that secrete hard calcareous exoskeletons, giving an amazingly firm structure. These colonial “hard corals” form elaborate finger-shaped, branching, or mound shaped structures and can create masses of limestone that stretch for tens or even hundreds of miles. These corals continue to build on top of the skeletal remains of older colonies and eventually a reef is established. Today, richly diverse coral reefs are found in the tropics along coastlines, on the margins of volcanic islands, and as isolated coral atolls. According to a website I found, coral reefs are home to over 25 percent of all marine life and are among the world's most fragile and endangered ecosystems. In the last few decades over 35 million acres of coral reefs have been destroyed and many other reefs have been damaged. One of the major threats to coral reefs is coral bleaching. Coral bleaching is a phenomenon in which corals lose their distinctive color because they expel the zooxanthellae that live within them. This bleaching is caused by stress to the corals. If a coral is fully bleached, it will turn entirely white, and will die unless the stress on the coral is reduced, allowing the zooxanthellae to return to the coral. The main causes of stress to the coral reefs are the rising water temperatures of the ocean and increased ultraviolet radiation. Two other factors that are believed to be causing stress to the reefs are increased salinity and increased sedimentation. Coral reefs are important, because they remove carbon dioxide from the atmosphere and help regulate atmospheric temperatures, they protect our coastlines from erosion, act as homes to many marine animals, they are used for fishing, provide people with jobs, and of course they play a significant role in tourism.

Environmental News Network staff. (2000, October 5). NOAA Delivers Early Warning of Coral Bleaching. CNN. Retrieved April 11, 2009, from http://archives.cnn.com/2000/NATURE/10/05/coral.bleaching.enn/

Goreau, T., & Hayes, R. (1994). Coral Bleaching and Ocean Hot Spots. The Global Coral Web. Retrieved April 11, 2009, from http://www.globalcoral.org/Coral%20Bleaching%20&%20Ocean%20Hot20Spots.pdf

(2002). Coral Reef Ecosystem. The Reef Relief Web. Retrieved April 11, 2009, from http://www.reefrelief.org/coralreef/