Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

For corals adapting to climate change, it's survival of the fattest -- and most flexible

09.07.2014

Study suggests best targets for environmental conservation

The future health of the world's coral reefs and the animals that depend on them relies in part on the ability of one tiny symbiotic sea creature to get fat—and to be flexible about the type of algae it cooperates with.


This is a closeup of polyps of Orbicella faveolata, more commonly known as boulder coral.

Credit: Image courtesy of The Ohio State University.

In the first study of its kind, scientists at The Ohio State University discovered that corals—tiny reef-forming animals that live symbiotically with algae—are better able to recover from yearly bouts of heat stress, called "bleaching," when they keep large energy reserves—mostly as fat—socked away in their cells.

"We found that some coral are able to acclimatize to annual bleaching, while others actually become more susceptible to it over time," said Andréa Grottoli, professor in the School of Earth Sciences at Ohio State. "We concluded that annual coral bleaching could cause a decline in coral diversity, and an overall decline of coral reefs worldwide."

The study, which appears in the July 9 online edition of Global Change Biology, indicates that some coral species will almost certainly decline with global climate change, while others that exhibit large fat storage and flexibility in the types of algae they partner with will stand a better chance of enduring repeated rounds of stress as oceans get hotter.

It also suggests that the most adaptable species would make good targets for conservation efforts because they are most likely to survive.

"If we conserve reefs that contain coral species with these survival traits, then we're hedging our bets that we might be able to preserve those reefs for an extra decade or two, buying them enough time to acclimatize to climate change," Grottoli said.

Corals are essentially colorless; the brilliant browns, yellows, and greens that we associate with them are actually the colors of algae living inside the corals' animal cells. That's why, when stressed coral dump most of the algae from their cells, their bodies appear pale, or "bleached."

Bleached corals can recover by growing more algae or acquiring new algae once water temperatures return to normal. This research shows that corals' ability to switch the type of algae that they internally grow has a large effect on their recovery.

But if corals don't recover and reefs die, thousands of fish species and other sea creatures lose their habitat.

Normally, bleaching is a rare event. But by 2025, Caribbean waters are expected to be hot enough that the coral living there will be stressed to the point of bleaching once a year. The rest of the tropics are expected to experience annual bleaching by 2050.

Previous studies have only followed coral through one bleaching event, or through two events several years apart. So Grottoli and her team tested what would happen if they subjected some common Caribbean corals to bleaching for two years in a row.

Corals can supplement their diet by eating plankton, but they get most of their energy from their symbiotic relationship with algae. The algae get nutrients from the coral, and the corals get to siphon off sugars that the algae produce in photosynthesis. Like humans, corals can store excess energy as fat.

Two key survival strategies emerged in this study: the most resilient corals stored up fat reserves in times of plenty, and were willing to switch to a new dominant algal type in order to gather food in times of stress. Corals that didn't store fat or were stuck with their algal partner didn't fare as well.

And species that bounced back from one round of bleaching didn't necessarily bounce back a second time.

"We found that the research on single bleaching events is misleading," Grottoli said. "Species that we think are resilient to temperature stress are actually susceptible and vice versa when stressed annually."

Grottoli and her colleagues tested three corals from Puerto Morelos Reef National Park, off the coast of Mexico. Two years in a row, they plucked samples of Porites divaricata, Porites astreoides, and Orbicella faveolata—more commonly known as finger coral, mustard hill coral, and boulder coral—from the ocean floor, and placed them in warm water tanks in an outdoor lab until the corals bleached. Both times, the researchers returned the corals to the ocean to let them recover. They measured several indicators of how well the different species recovered, including the number and type of algae present in the corals' cells and remaining energy reserve.

The mustard hill coral kept lower fat reserves, and partnered with only one algal species. It recovered from the first round of bleaching but not the second. The boulder coral kept moderate fat reserves, but partnered with six different algae and changed between dominant algal types following each bleaching. It recovered from both rounds of bleaching, though it's growth slowed.

The real winner was the finger coral, which switched completely from one algal partner type to another over the course of the study, and had the largest fat reserves—47 percent higher than the boulder coral or mustard hill coral. The finger coral was barely even affected by the second bleaching and maintained a healthy growth rate.

The bottom line: as some species adapt to climate change and others don't, there will be less diversity in reefs, where all the different sizes and shapes of coral provide specialized habitats for fish and other creatures. Interactions among hosts, symbionts, predators and prey would all change in a domino effect, Grottoli said. Reefs would be more vulnerable to storms and disease in general.

It sounds like a bleak picture.

"We're actually a bit optimistic, because we showed that there's acclimation in a one-year window, that it's possible," she said. "In two of our three coral species, we have recovery in six weeks. The paths they took to recovery are different, but they both got there."

###

Coauthors on the study included Grottoli's former graduate students Stephen Levas, Verena Schoepf, and Justin Baumann; Ohio State research associate Yohei Matsui; and Mark Warner of the University of Delaware and his graduate students Matthew Aschaffenburg and Michael McGinley.

This research was funded by the National Science Foundation.

Pam Frost Gorder | Eurek Alert!

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

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: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Detecting damage in non-magnetic steel with the help of magnetism

23.07.2018 | Materials Sciences

Researchers move closer to completely optical artificial neural network

23.07.2018 | Information Technology

Enabling technology in cell-based therapies: Scale-up, scale-out or program in-place

23.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>