Featured Research

from universities, journals, and other organizations

Close-up of coral bleaching event

Date:
June 3, 2014
Source:
University of Georgia
Summary:
Ecologists have shed light on exactly what happens to coral during periods of excessively high water temperatures. Their study documents a coral bleaching event in the Caribbean in minute detail and sheds light on how it changed a coral's community of algae -- a change that could have long-term consequences for coral health, as bleaching is predicted to occur more frequently in the future.

Dustin Kemp takes samples from a healthy Orbicella faveolata coral in the Caribbean.
Credit: Bill Fitt/UGA

New research by University of Georgia ecologists sheds light on exactly what happens to coral during periods of excessively high water temperatures. Their study, published in the journal Limnology and Oceanography, documents a coral bleaching event in the Caribbean in minute detail and sheds light on how it changed a coral's community of algae—a change that could have long-term consequences for coral health, as bleaching is predicted to occur more frequently in the future.

Millions of people around the world depend on coral reefs and the services they provide. While coral reefs make up less than 0.1 percent of the sea floor, they serve as habitats for about 25 percent to 35 percent of all the oceans' fishes, roughly 500 million people worldwide rely on them as a source of protein and for coastal protection, and they are responsible for billions of dollars in tourism and fisheries revenue.

Corals, in turn, depend upon single-celled algae that inhabit them, providing most of their food and giving them their color. But many species of these algae are highly sensitive to temperature, and are unable to survive as ocean waters warm. The coral can expel these algae when the water temperature grows too high, a phenomenon known as coral bleaching.

Lead author Dustin Kemp, a postdoctoral associate in the UGA Odum School of Ecology, had the opportunity to study a bleaching event while conducting research at a reef off Puerto Morelos, Mexico. He and his colleagues had been working there since 2007, taking samples seasonally from six colonies of Orbicella faveolata, also known as mountainous star coral, and their associated symbiotic algae.

Orbicella is the major reef-building coral in most of the Caribbean, but although common, it has an unusual trait. While most species of coral associate with just one dominant type of symbiotic algae, O. faveolata is able to associate with up to four co-dominant types at once—some of which are heat-tolerant and some of which are not—making it a particularly interesting coral to study.

In October 2009, the researchers' sampling trip coincided with a period of unusually high temperatures, allowing them the rare opportunity to collect samples while a bleaching event was taking place.

"We were able to follow this coral at a very high precision and document how diverse assemblages of symbiotic algae are differently affected by the bleaching phenomenon," Kemp said. "This was probably the first study ever to look at it under natural conditions this closely."

Kemp took hundreds of samples approximately every 12 inches along established transects—a narrow section where measurements are taken—across all six coral colonies. He made sure to include samples from areas that appeared bleached as well as from those that still retained color. Because they had been collecting at the site for two years, and continued collecting after this event, the researchers were able to compare the communities of symbiotic algae before, during and after bleaching.

They observed that before the bleaching event, these particular corals contained three different types of algae, two of which were somewhat tolerant of the warm-water bleaching perturbation.

During the bleaching event, heat-sensitive algae were found to be much less prevalent while the heat-tolerant algae remained. Two months later, heat-tolerant algae had taken over the parts of the coral formerly occupied by the heat-sensitive algae.

"The corals didn't die after this bleaching event, they recovered—and that's good, that's important—but there could be potential tradeoffs associated with the shift to heat-tolerant algae," said Kemp, adding that, for example, some heat-tolerant algae may provide less food than those they might replace. "That question of tradeoffs is what we're working on now."

Kemp is currently conducting research at reefs in the Caribbean and Pacific, looking at how heat-tolerant algae affect corals in areas where corals have been documented to have stable, long-term associations with heat-tolerant algae.

"In the Caribbean, we've lost 80 percent of the corals just in my lifetime," Kemp said. "We know that increased ocean temperatures are one of the major threats to coral reefs worldwide. So understanding coral-algae dynamics, and how different algae can handle increased temperature, is important to see how the whole ecosystem will be affected by this environmental perturbation."


Story Source:

The above story is based on materials provided by University of Georgia. The original article was written by Beth Gavrilles. Note: Materials may be edited for content and length.


Cite This Page:

University of Georgia. "Close-up of coral bleaching event." ScienceDaily. ScienceDaily, 3 June 2014. <www.sciencedaily.com/releases/2014/06/140603135827.htm>.
University of Georgia. (2014, June 3). Close-up of coral bleaching event. ScienceDaily. Retrieved August 27, 2014 from www.sciencedaily.com/releases/2014/06/140603135827.htm
University of Georgia. "Close-up of coral bleaching event." ScienceDaily. www.sciencedaily.com/releases/2014/06/140603135827.htm (accessed August 27, 2014).

Share This




More Earth & Climate News

Wednesday, August 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Big Waves, Minor Flooding from Hurricane

Big Waves, Minor Flooding from Hurricane

AP (Aug. 27, 2014) Thundering surf spawned by Hurricane Marie pounded the Southern California coast Wednesday, causing minor flooding in a low-lying beach town. High surf warnings were posted for Los Angeles County south through Orange County. (Aug. 27) Video provided by AP
Powered by NewsLook.com
Calif. Quake Underscores Need for Early Warning

Calif. Quake Underscores Need for Early Warning

AP (Aug. 26, 2014) Researchers at UC Berkeley are testing a prototype of an earthquake early warning system that California is pursuing years after places like Mexico and Japan already have them up and running. (August 26) Video provided by AP
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Brazil Tries Genetically Modified Mosquitoes to Fight Dengue

Brazil Tries Genetically Modified Mosquitoes to Fight Dengue

AFP (Aug. 25, 2014) A factory in the industrial state of Sao Paulo produces genetically modified mosquitoes to fight dengue, a deadly tropical disease more prevalent in Brazil than anywhere else in the world. Duration: 00:57 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins