Athens, Ga. Increased seawater temperatures are known to be a leading cause of the decline of coral reefs all over the world. Now, researchers at the University of Georgia have found that extreme low temperatures affect certain corals in much the same way that high temperatures do, with potentially catastrophic consequences for coral ecosystems. Their findings appear in the early online edition of the journal Global Change Biology.
Lead author Dustin Kemp, a postdoctoral associate in the UGA Odum School of Ecology, said the study was prompted by an abnormal episode of extended cold weather in January and February 2010. Temperatures on inshore reefs in the upper Florida Keys dropped below 12 C (54 F), and remained below 18 C (64 F) for two weeks. Kemp and his colleagues had planned to sample corals at Admiral Reef, an inshore reef off Key Largo, just three weeks after the cold snap. When they arrived, they discovered that the reef, once abundant in hard and soft corals, was essentially dead. "It was the saddest thing I've ever seen," Kemp said. "The large, reef-building corals were gone. Some were estimated to be 200 to 300 years old and had survived other catastrophic events, such as the 1998 El Nio bleaching event. The severe cold water appeared to kill the corals quite rapidly."
Odum School Professor William Fitt, Kemp's doctoral advisor and one of the paper's co-authors, realized that the team had a unique opportunity. "Nearly 100 years ago, Alfred Mayer described the temperature tolerance of different corals in the Dry Tortugas and found very similar results," Kemp said. "We decided to take the next step and learn how and why the cold temperatures caused the corals to die."
The researchers took samples of Siderastrea sidereaone of the few reef-building corals to survivefrom Admiral Reef. They also took samples of three common Florida Keys corals, Montastraea faveolata, Siderastrea sidereaand Porites astreoides from Lit
|Contact: Dustin Kemp|
University of Georgia