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.
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.
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!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
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...
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...
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...
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....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine