Climate Number: 180 Square Miles
The coral reefs around the 3,700 square mile Florida Keys National Marine Sanctuary provide habitat for 5,500 species as well nursing, feeding and breeding grounds that support a 20 million pound per year fishery. Water temperatures in the sanctuary fluctuate annually between about 68 and 86 degrees Fahrenheit. These waters, which reach their annual peak during the summer months, are currently approaching 85 degrees. While coral polyps can only survive in warm waters, if waters become too warm (86-87 degrees Fahrenheit is considered the “danger zone” for these corals) coral polyps lose the algae that they depend on for food and begin to die. This phenomenon, known as “coral bleaching,” has become more common as Atlantic sea surface temperatures have warmed, which they have been doing since the 1870′s. During El Niño years, such as 1982-1983 and 1997-1998, conditions where water temperatures are particularly high for an especially long period of time are common. Florida Keys coral cover fell from about 11.7 percent before the bleaching events that happened during the El Niño years of 1997-1998 to about 6.7 percent in 2005. This means that 180 square miles of shallow waters that were full of colorful coral ecosystems in 1996 had little or no living coral in 2005.
For Comparison: You could fit close to six Manhattans into 180 square miles; 180 square miles is also about the same size as Miami and Atlanta combined.
Seasons: Summer
Sources: Causey, Billy: “The History of Massive Coral Bleaching and other Perturbations in the Florida Keys.” In Chapter 6 of Coral Reefs in the U.S. and the Carribean. U.S. Coral Reef Information Service: National Oceanic and Atmospheric Administration and Eakin, Mark. Testimony before the House Committee on Natural Resources. U.S. House of Representatitves,17 April 2007 and Hoegh-Guldberg et al. “Coral Reefs Under Rapid Climate Change and Ocean Acidification.” Science 318 (2007): 1737 and United States. National Oceanic and Atmospheric Administration. Florida Keys National Marine Sanctuary: Visitor Information. 28 April 2008. Accessed Online: 18 September 2008 < http://floridakeys.noaa.gov/visitor_information/welcome.html> United States. National Oceanographic and Atmospheric Administration. NOAA Coral Reef Initiative. 1997. Accessed Online 18 September 2008 Wilkinson, C., Souter, D. (2008). Status of Caribbean coral reefs after bleaching and hurricanes in 2005. Global Coral Reef Monitoring Network and Reef and Rainforest Research Centre, Townsville, 152 p.
