01.01.14 GUAM From Saving our Micronesia Blog

2013 CORAL BLEACHING by Roxanna Miller

With the onset of human-induced climate change, marine scientists are taking a closer look at how marine organisms respond to warming temperatures, sea-level rise, and more acidic oceans.  One way in which corals respond to climate change and warming temperatures is through coral bleaching.  Coral bleaching is what happens when a coral animal becomes stressed and expels its symbiotic zooxanthellae (a special kind of algae that lives inside the coral).  These zooxanthellae are what give coral a lot of its color, so when corals expel their algae they appear white (hence the name coral bleaching).  Bleached corals may regain their zooxanthellae and become healthy and colorful again, but if unusually warm water temperatures persist and the corals are without their important algae partners for too long, they can die.  With temperatures getting warmer and warmer, at a faster rate than normal, it is likely that the world’s coral reefs will see much more frequent and increasingly severe coral bleaching events.  Since corals are an important part of coral reef ecosystems, the death of corals and loss of the structure they provide can have a negative impact on the whole ecosystem.  The structures that coral form not only provide homes to many fish, but corals are also a food source to some fish and invertebrates.  For Guam, corals are important because of the shelter they provide to a lot of fish that we enjoy consuming, they are one of the main reasons why Guam gets over one million tourists every year, and they also help protect the island from large waves.  For these reasons local coral reef managers are interested in better understanding how Guam’s corals and the coral reef ecosystem as a whole are affected by coral bleaching, and whether or not we can expect our reefs to adapt to the changing conditions. 


A massive Porites sp. coral which is bleached.  Some areas have already begun to die as evidenced by the algae covered areas.  Photo taken by Dave Burdick.