Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Coral Reef Resilience: Better Feeders Survive Bleaching

28.04.2006


Eating as the key to health
Coral bleaching has severely damaged or killed 30 percent of the world’s coral reefs, turning brightly colored coral a ghostly white. Research shows that some “super-feeding” corals can survive. Photo: Jon Witman/Brown University


Global warming and other threats are killing coral reefs through a phenomenon known as bleaching. But why do some corals survive? A new study, published in Nature, is the first to document a trait that helps some coral species live through, and recover from, bleaching. The survivors’ secret: Ramped up feeding rates.

In an experiment with three species of Hawaiian corals researchers found that, when bleached, the branching coral Montipora capitata sharply increased its intake of tiny plankton, making it much more likely to bounce back. The findings suggest that any coral, regardless of shape or location, may recover from bleaching if it can ramp up feeding.

James Palardy, a Brown University graduate student and co-author of the Nature paper, said the results indicate that these corals may become the dominant species in reefs and could play a role in protecting these critical marine ecosystems.



“These ‘super-feeders’ have an ecological advantage, one that may protect reefs from extinction,” Palardy said. “If our results hold up with other species, we may well see that these resilient corals are the future for our reefs.”

Coral reefs reduce beach erosion, support tourism and serve as breeding grounds and habitat for fish. A 2006 report by the United Nations Environment Programme put the value of coral reefs at $100,000 to $600,000 per square kilometer per year.

But the UNEP report states that 30 percent of the world’s coral reefs are severely damaged or dead and that 60 percent of remaining reefs will vanish by 2030. Several factors are to blame, from pollution to overfishing. Scientists say the biggest new threat is global warming. Because corals are highly sensitive to temperature, even small amounts of warming can trigger bleaching.

When water temperatures rise, coral expel single-celled algae called zooxanthellae, which live inside coral tissue and give corals their color and, more importantly, supply the bulk of their food energy. If bleaching persists, corals die, leaving behind ghostly limestone skeletons.

Some corals can survive bleaching. The reasons for this, however, aren’t well understood. Palardy and his colleagues had a hunch: In the absence of algae-derived nutrition, corals may tap energy reserves or increase feeding, a process where corals use their tiny tentacles to “grab” passing plankton and stuff them into their stomachs.

To study the role metabolism and feeding might play in coral resiliency, Palardy, a Brown Ph.D. student in the Department of Ecology and Evolutionary Biology, collaborated with Andréa Grottoli, an assistant professor of geological sciences at Ohio State University, and Lisa Rodrigues, a post-doctoral research fellow in biology at Villanova University.

The team took chunks of three types of healthy Hawaiian corals – M. capitata, another branching coral called Porites compressa and the mounding coral Porites lobata – from colonies off the coast of Oahu and put them in eight outdoor tanks. Water in four of the tanks was kept at 27° C, the typical reef water temperature. In the other four, water temperature was elevated to 30° C, warm enough to trigger bleaching. After 30 days in the tanks, the team measured chlorophyll concentrations, photosynthetic rates, and lipid levels in some corals. The remaining corals were returned to the reef to recover.

After two weeks on the reef, researchers covered some of the healthy and bleached corals with fine mesh boxes, which kept plankton out of reach. The boxes went over the corals eight hours a day, then removed for an hour each night for five days. The goal: Empty their stomachs, so that the plankton the corals consumed could be accurately measured. Researchers dissected the corals and painstakingly counted plankton in their stomachs. Researchers also created a system of measurements that gauged the corals’ energy input from feeding.

Four weeks later, the scientists weighed the remaining corals and again measured chlorophyll concentrations, photosynthetic rates and lipid levels.

The results: P. compressa and P. lobata depleted their energy reserves during bleaching. And when these bleached and unbleached corals were compared, feeding didn’t increase. In contrast, the feeding rates of bleached M. capitata increased five-fold, allowing them to replenish their energy reserves – making it more likely that they’ll survive and spawn after a bleaching event.

“The results were a surprise,” Palardy said. “Previous studies showed that thick tissue layers or mounded shapes made corals resilient. But we found a new resiliency factor – feeding. In evolutionary terms, corals that eat more may win.”

The National Science Foundation, the Mellon Foundation, and a William Penn Fellowship funded the work.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Microhotplates for a smart gas sensor

22.02.2017 | Power and Electrical Engineering

Scientists unlock ability to generate new sensory hair cells

22.02.2017 | Life Sciences

Prediction: More gas-giants will be found orbiting Sun-like stars

22.02.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>