Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Tiny polyps need 2 kinds of carbon to survive coral bleaching

How well ocean reefs recover from the growing damage caused by warming sea temperatures depends both on how much the tiny coral polyps can eat, and how healthy they can keep the microscopic algae that live inside their bodies.

New research intended to dissect one of the planet’s most fertile and endangered ecosystems may change the way scientists look at this symbiotic partnership, shifting it from a case where the polyps function only as landlords to one where the tiny creatures actually nurture their algae.

Preliminary findings were presented today in two papers at the 2008 Ocean Sciences meeting in Orlando. The research focuses on the key role that carbon plays on the recovery of damaged coral reefs.

Andrea Grottoli, an assistant professor of earth sciences at Ohio State University, has spent the last 14 years studying two common forms of coral that populate the reefs near the Hawaii Institute of Marine Biology.

Two years ago, she reported that one of the corals she tested, Montipora capitata, or “rice” coral, was able to recover rapidly from bleaching because it increased its rate of feeding five-fold compared to how fast another form, Porites compressa, or “finger” coral, fed.

This strategy of gluttony enabled Montipora to survive the long-term damage that corals suffer when sea temperature climbs beyond the narrow 4 – 6 degree C range, where Porites might not.

What wasn’t clear from the earlier experiments was how the corals actually made use of carbon for their survival.

“Corals get carbon in two ways,” she said, “either through photosynthesis by the algae kept inside their bodies, or by feeding on the zooplankton that comprise their diets.”

While corals can get all the carbon they need from the algae’s photosynthesis, “they still get some of what they need through normal feeding.”

But when seawater temperatures climb, the coral will either jettison the algae altogether, or the algal cells will lose the pigments essential for photosynthesis to deliver the needed carbon. Without the algae, corals appear white, which is often referred to as “bleached.” Prolonged bleaching can lead to the coral dying. Either case presents a serious threat to the tiny creatures.

Grottoli wanted to determine exactly how the coral obtained its carbon and, in turn, how it used the material to survive. She placed samples of both healthy and bleached corals of both types in tanks mimicking actual ocean conditions. In one set of experiments, she pumped in seawater containing higher-than-normal levels of a carbon isotope, C-13. In another, she fed the corals zooplankton that were also heavily laced with the carbon isotope.

“We could track the carbon and determine if it was coming from either the photosynthetic process or from the animals’ feeding,” she said, “and then see how it was ultimately used by the animals. We could tell whether the process differed if the corals were healthy or bleached, or one species or the other.”

The experiments readily showed, as expected, that healthy corals had much more of the seawater-labeled carbon than did bleached corals, she said.

“But we could also see that in the healthy coral, the carbon was transferred into the algae where it is used for photosynthesis, and ultimately ends up in the animals’ skeleton,” Grottoli said. “So the corals are using photosynthetic carbon for calcification and to meet their daily metabolic demands.”

The carbon consumed while feeding, however, isn’t ending up in the skeleton, she said. Instead, it’s ending up both in the tissue of the coral polyp or inside the algae. With bleached samples, the coral is apparently feeding carbon to the algae.

“That’s what our work suggests and this is new. We’ve known that nutrients like nitrogen and phosphorus are exchanged in this way but nobody ever knew that this was happening with carbon,” she said.

Coral polyps ready to feed.
“This suggests that there is a great deal more coupling between the coral and the algae than we had thought. Once the coral gets the carbon from feeding into its system, it locks it in, using it for energy storage and tissue growth, and when bleached, to feed the algae.”

The bottom line, Grottoli says, is that the photosynthetic carbon is used for metabolic demands and calcification, while the carbon gained from feeding is used for tissue growth.

“Without both forms, the coral simply cannot fully recover,” she said.

“All corals need both photosynthesis and feeding for recovery and the rate of those two processes is the key to whether the coral can actually meet all its metabolic demands and ultimately recover.”

Grottoli’s work is supported in part by the National Science Foundation. Along with Grottoli, Adam Hughes, a postdoctoral fellow in her lab, and Tamara Pease, an assistant professor of marine science at the University of Texas at Austin, worked on the project.

Andrea Grottoli | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

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: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

Gene therapy shows promise for treating Niemann-Pick disease type C1

27.10.2016 | Life Sciences

Solid progress in carbon capture

27.10.2016 | Power and Electrical Engineering

More VideoLinks >>>