Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Darwin Discovered to Be Right: Eastern Pacific Barrier is Virtually Impassable by Coral Species

28.08.2012
A coral species that is found in abundance from Indonesia eastward to Fiji, Samoa, and the Line Islands rarely crosses the Eastern Pacific Barrier toward the coast of the Americas, according to a team of researchers led by Iliana Baums, an assistant professor of biology at Penn State University.
Darwin hypothesized in 1880 that most species could not disperse across the marine barrier, and Baums's study is the first comprehensive test of that hypothesis using coral. The results of the scientific paper, which will be published in the journal Molecular Ecology, has important implications for climate-change research, species-preservation efforts, and the economic stability of the eastern Pacific region, including the Galapagos, Costa Rica, Panama, and Ecuador.

The Eastern Pacific Barrier (EPB) -- an uninterrupted 4,000-mile stretch of water with depths of up to 7 miles -- separates the central from the eastern Pacific Ocean. In his writings, Darwin had termed this barrier "impassable" and, since Darwin's time, scientists have confirmed that many species of marine animals cannot cross this oceanic divide. However, until now, researchers had not performed a comprehensive analysis of the impact of the barrier on coral species. "The adult colonies reproduce by making small coral larvae that stay in the water column for some time, where currents can take them to far-away places," Baums said. "But the EPB is a formidable barrier because the time it would take to cross it probably exceeds the life span of a larva."

To test whether or not coral larvae are able to travel across the barrier, Baums and her team chose a particularly hearty species called Porites lobata. "Compared with other coral species, Porites lobata larvae seem able to survive for longer periods of time; for example, the weeks that are required to travel across the marine barrier," Baums said. "This species also harbors symbionts in its larvae that can provide food during the long journey. In addition, the adults seem able to brave more extreme temperatures, as well as more acidic conditions. So, if any coral species is going to make it across, it is this one."

Baums and her team hypothesized that coral larvae originating in the central Pacific might be pushed along the North Equatorial Counter Current, which flows from west to east and becomes stronger and warmer in years with an El Niño Southern Oscillation event -- a climate pattern that occurs about every five years. "Coral larvae are not very mobile," Baums said. "So the only way coral larvae originating to the west of the barrier could travel to the east is along an ocean current, and warming of a current like the North Equatorial Counter Current would help larvae survive. If coral have traveled along this current in the past, we should find populations that are genetically similar living from the Galapagos to Costa Rica, Panama, and Ecuador."

The team members collected coral samples of the Porites lobata species from both sides of the Eastern Pacific Barrier and performed genetic tests using special markers called microsatellites -- repeating sequences of DNA that are informative for the purpose of distinguishing among individuals. "We found that Darwin was right: the EPB is a very effective barrier," Baums said. "For the most part, samples we found to the east are genetically dissimilar to those we found to the west. This means that coral larvae originating in the central Pacific simply are not making it across the ocean to the Americas."

The only exception, the team found, was a relatively small population of Porites lobata living near Clipperton Island, which is located just north and west of the Galapagos. The samples collected there were genetically similar to samples found throughout the central Pacific, indicating that the species had migrated there from the west relatively recently. "Interestingly, the coral that are lucky enough to cross the EPB to Clipperton Island stay there and don't go any farther," Baums explained. "In other words, we find that Porites lobata are not migrating south and east to the Galapagos after making it to Clipperton. We believe this is because these coral are adapted to the warmer conditions that their parents enjoyed to the west of the EPB; for example, near the Line Islands, Fiji, and Samoa. "Coral reefs thrive in shallow water in areas where the annual mean temperature is about 64 degrees Fahrenheit," Baums said. "The eastern Pacific tends to be much cooler; in part, because of a process called upwelling -- a phenomenon that occurs when winds stir up cold, deep ocean water, pulling it to the surface. Clipperton Island may provide a similar-enough environment to the Central Pacific, but the Galapagos area simply may be too cool."

The team's findings about the ability of coral to travel across the marine barrier have important implications for the economic stability of the eastern Pacific, the region's species-conservation efforts and, more broadly, for the impact of climate change on tropical ecosystems. The Galapagos, Costa Rica, Panama, and Ecuador all rely heavily on tourism. Tourism, in turn, relies on healthy reefs that divers can visit and the sale of shellfish and lobster -- species that are maintained, in large part, by the presence of coral communities.

"The take-home message is that coral populations in the eastern Pacific need to be protected," Baums said. "That is, in the event of any large-scale coral crisis, we cannot count on coral populations in the eastern Pacific being replenished by larvae from the west." Baums explained that, especially as the Earth's surface continues to warm, such a crisis to coral reefs is not unlikely. During the El Niño Southern Oscillation events that occurred from 1982 to 1983 and from 1997 to 1998, some of the reefs experienced a 90-percent loss. Although they ultimately were able to bounce back, a stronger El Niño event might spell extinction for some coral species.

In addition to Baums, other researchers who contributed to the study include Jennifer Boulay and Nicholas R. Polato at Penn State and Michael E. Hellberg at the Louisiana State University.

The research was funded by the National Science Foundation.

[ Katrina Voss ]

CONTACTS
Iliana Baums: 814-867-0491, baums@psu.edu
Barbara Kennedy (PIO): 814-863-4682, science@psu.edu

GRANT NUMBERS
National Science Foundation (OCE- 0550294)

Barbara Kennedy | EurekAlert!
Further information:
http://www.psu.edu
http://science.psu.edu/news-and-events/2012-news/Baums8-2012

More articles from Ecology, The Environment and Conservation:

nachricht Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH

nachricht Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt

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: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>