Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UGA ecologists provide close-up of coral bleaching event

04.06.2014

Study documents corals before, during and after October 2009 episode

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.


An Orbicella faveolata coral in the Caribbean shows bleached areas adjacent to areas that retain their color. Bleaching occurs when heat-sensitive symbiotic algae that inhabit corals are expelled during episodes of excessively high water temperatures. (Credit: Dustin Kemp/UGA)

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."

The study's coauthors are Xavier Hernandez-Pech and Roberto Iglesias-Prieto of the Universidad Nacional Autónoma de México, William K. Fitt of the UGA Odum School of Ecology and Gregory W. Schmidt of the UGA department of plant biology. The research was supported by the National Science Foundation and the World Bank. The paper is available online at http://aslo.org/lo/pdf/vol_59/issue_3/0788.pdf.

For more information about the Odum School of Ecology, see www.ecology.uga.edu.

Dustin Kemp | Eurek Alert!
Further information:
http://news.uga.edu/releases/article/ecologists-close-up-coral-bleaching-event-0614/

Further reports about: Ecology October UGA corals ecologists heat-sensitive perturbation phenomenon species symbiotic temperature temperature

More articles from Ecology, The Environment and Conservation:

nachricht Making Oceans Plastic Free - Project tackles the problem of plastic pollution in the oceans
31.05.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

nachricht Nitrogen Oxides Emissions: Traffic Dramatically Underestimated as Major Polluter
31.05.2017 | Universität Innsbruck

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Hubble captures massive dead disk galaxy that challenges theories of galaxy evolution

22.06.2017 | Physics and Astronomy

New femto-camera with quadrillion fractions of a second resolution

22.06.2017 | Physics and Astronomy

Rice U. chemists create 3-D printed graphene foam

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>