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!
Upcycling 'fast fashion' to reduce waste and pollution
03.04.2017 | American Chemical Society
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences