Thriving Oceans

Coral bleaching is again making headlines as NOAA’s Coral Reef Watch Program has detected conditions in the Caribbean that may spark a rash of coral disease and bleaching.  Of particular concern to NOAA scientists is an expected increase in ocean temperatures through October 2009 that can lead to the discharging of the symbiotic zooxanthella algae residing in coral tissues.  Keeping things simple, zooxanthellae are vital to coral survival as they, through photosynthesis, provide much needed energy and nutrients.  In return, the coral provides the zooxanthellae with shelter and a constant supply of carbon dioxide for its photosynthetic processes.

According to the Coral Reef Watch Program:

Scientists are concerned that bleaching may reach the same levels or exceed those recorded in 2005, the worst coral bleaching and disease year in Caribbean history. In parts of the eastern Caribbean, as much as 90 percent of corals bleached and over half of those died during that event.” 

“Just like any climate forecast, local conditions and weather events can influence actual temperatures. However, we are quite concerned that high temperatures may threaten the health of coral reefs in the Caribbean this year,” said C. Mark Eakin, Ph.D., coordinator of NOAA’s Coral Reef Watch.

Prolonged coral bleaching of more than a week can lead to coral death and the subsequent loss of coral reef habitats for a range of marine life. It also affects local economies and tourism.

Other factors that can lead to coral bleaching include: ocean temperature, solar irradiation, inorganic nutrients, freshwater dilution, sedimentation, pollutants/chemicals, and diseases.

Credit: NOAA