The team, led by Penn State Assistant Professor of Biology Todd LaJeunesse, found that a rare species of algae that is tolerant of stressful environmental conditions proliferated in corals as the more-sensitive algae were being expelled from corals. The results will be published in the online version of the journal Proceedings of the Royal Society B on 9 September 2009.
"Symbiodinium trenchi is normally a rare species of micro-alga in the Caribbean," said LaJeunesse. "Because the species is apparently tolerant of high or fluctuating temperatures, it was able to take advantage of the warming event and become more prolific. In this way, Symbiodinium trenchi appears to have saved certain colonies of coral from the damaging effects of unusually warm water. As ocean temperatures continue to rise as a result of global warming, we can expect this species to become more common and persistent. However, since it is not normally associated with corals in the Caribbean, we don't know if its increased presence will benefit or harm corals in the long term."
According to LaJeunesse, certain species of algae have evolved over millions of years to live in symbiotic relationships with certain species of corals. The photosynthetic algae provide the corals with nutrients and energy, while the corals provide the algae with nutrients and a place to live. "There is a fine balance between giving and taking in these symbiotic relationships," said LaJeunesse. "If Symbiodinium trenchi takes from the corals more than it gives back, then over time we will see the health of the corals diminish."
In 2005, sea surface temperatures in the Caribbean Ocean rose by up to two degrees Celsius above normal for a period of three to four months, high enough and long enough to severely stress the natural symbioses. This process of damaged or dying algae being expelled from the cells of corals is known as bleaching because it leaves behind bone-white coral skeletons that soon will die without their symbiotic partners.
During the summer of 2005, prior to the bleaching event, LaJeunesse and his colleagues collected samples of coral and algae from two locations near Barbados in the Caribbean. "We collected the samples as part of an effort to document the diversity of Symbiodinium species around the world and to study how relationships between certain species of corals and algae differ across geographic space," he said.
By late November, water temperatures had peaked and many corals were bleached. "Finding out about the bleaching event was bittersweet," said LaJeunesse. "It was upsetting to see how severe the impact was to the coral communities, but I also knew it would be a good opportunity to learn more about what happens to corals and their algal partners during times of acute stress. In fact, I knew that this would be one of the first times that anyone had had the opportunity to conduct a community-wide study of corals and algae before, during, and after a bleaching event."
The team collected samples of coral and algae during the bleaching event and again two years after ocean temperatures returned to normal. In the laboratory, they sequenced the organisms' DNA to identify the species.
"During the bleaching event, we found that Symbiodinium trenchi, which we rarely find in the Caribbean, had increased in frequency by 50 percent, or more, within coral species that are most sensitive to warm water. We also saw this species in corals where it had never been before. Two years later, we found that the abundance and occurrence of Symbiodinium trenchi had diminished significantly," said LaJeunesse. Today, the symbioses have mostly recovered to their normal state, and the corals have been repopulated by their typical algal symbionts," he said.
Although Symbiodinium trenchi appears to have saved some Barbadian corals from possibly dying in 2005, LaJeunesse is concerned that the species might not be good for the corals in the long term in the event that warming trends continue and Symbiodinium trenchi becomes more common. "Because Symbiodinium trenchi does not appear to have successfully co-evolved with Caribbean coral species, it may not provide the corals with adequate nutrition," he said.
In the future, LaJeunesse plans to further investigate the relationships among Symbiodinium trenchi and Caribbean coral species. "We're interested in looking at how Symbiodinium trenchi behaves in other regions of the world where it is naturally common. We also want to look more closely at the give-and-take relationship between Symbiodinium trenchi and corals in the Caribbean.
This research was supported by the U. S. National Science Foundation, Florida International University, Penn State University, and the University of the West Indies.
Barbara K. Kennedy | EurekAlert!
Minimized water consumption in CSP plants - EU project MinWaterCSP is making good progress
05.12.2017 | Steinbeis-Europa-Zentrum
Jena Experiment: Loss of species destroys ecosystems
28.11.2017 | Technische Universität München
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
An interdisciplinary group of researchers interfaced individual bacteria with a computer to build a hybrid bio-digital circuit - Study published in Nature Communications
Scientists at the Institute of Science and Technology Austria (IST Austria) have managed to control the behavior of individual bacteria by connecting them to a...
Physicists in the Laboratory for Attosecond Physics (run jointly by LMU Munich and the Max Planck Institute for Quantum Optics) have developed an attosecond electron microscope that allows them to visualize the dispersion of light in time and space, and observe the motions of electrons in atoms.
The most basic of all physical interactions in nature is that between light and matter. This interaction takes place in attosecond times (i.e. billionths of a...
Transistors based on carbon nanostructures: what sounds like a futuristic dream could be reality in just a few years' time. An international research team working with Empa has now succeeded in producing nanotransistors from graphene ribbons that are only a few atoms wide, as reported in the current issue of the trade journal "Nature Communications."
Graphene ribbons that are only a few atoms wide, so-called graphene nanoribbons, have special electrical properties that make them promising candidates for the...
08.12.2017 | Event News
07.12.2017 | Event News
05.12.2017 | Event News
08.12.2017 | Life Sciences
08.12.2017 | Information Technology
08.12.2017 | Information Technology