Research team investigates desolate sea-floor area in the southern Gulf of Mexico
Habitats surrounding natural oil seeps on the sea floor are multifaceted and diverse. During an expedition organized by MARUM, the Center for Marine Environmental Sciences, researchers discovered gas-bubble streams, massive gas hydrates, oil-soaked sediments, and deposits of heavy oil all closely spaced at a depth of around three kilometers.
Each of the different constituents: gas, light oil, and heavy oil congealed to asphalt, is home to its own characteristic group of organisms. The scientists have now published their initial results, along with photos from the remotely operated vehicle MARUM-QUEST, in the journal Biogeosciences.
“Recent years have seen a minor revolution in the field of marine research,” explains first author Dr. Heiko Sahling, a scientist at MARUM and the Geosciences Department of the University of Bremen. Many German research ships have been outfitted with state-of-the-art multibeam echosounders. These are of great help in the systematic search for natural seeps of oil and gas on the sea floor.
“In the past,” says Sahling, “this was more like the proverbial search for a needle in a haystack. Now we have found habitats on the sea floor that were unknown before.”
Scientists use the echosounders to detect gas bubbles in the water column. Where hydrocarbons are escaping, the acoustic signal is amplified in the water, and to some extent within the sea floor as well. The team of specialists from Bremen, Kiel, Vienna (Austria), Mexico City (Mexico) and Talahassee (Fla., USA) applied this modern technology during an expedition to the Bay of Campeche in the southern Gulf of Mexico.
Through a project financed by the German Research Foundation (Deutsche Forschungsgemeinschaft – DFG) scientists, under the leadership of Prof. Dr. Gerhard Bohrmann, have discovered hundreds of gas seeps and investigated a number of them in detail with the submersible vehicle MARUM-QUEST. Their goal was to reveal the processes of hydrocarbon movement at natural seeps. In what form are they released, how do they impact the biological assemblages on the sea floor, how rapidly does the oil break down, and what happens to the released gas?
“The gas, in part, is converted to gas hydrates, which form small mounds on the sea floor that are densely populated by meter-long tube worms,” continues Heiko Sahling. “Sometimes the mounds are broken open, allowing a view into several-meter-thick gas hydrates, a very rare observation until now. The gas hydrates are overlain by a reaction zone where microbial communities convert methane, carbonate is precipitated, and dense colonies of tube worms develop. These hold the mounds together and consume reduced sulfur compounds for nutrition. It is truly a remarkable habitat,” Sahling considers.
In addition to the gas, liquid oil also flows out of the sea floor. It ascends slowly through small white chimneys, the drops of oil attached by elongated threads or seeping through the sediments. “For organisms that are not adapted, the oil is harmful,” explains Heiko Sahling, “but the bountiful life at these sites shows that there are certain organisms that can even thrive on these hydrocarbons.”
On the other hand, some components of the so-called “heavy oil” dissipate. What remains forms flow structures of asphalt on the sea floor. “During the expedition we documented many of these unique structures,” says Heiko Sahling. “The asphalt covers hundreds of meters of the sea floor and thus also forms a habitat that is colonized by tube worms and bacterial mats."
Heiko Sahling, Christian Borowski, Elva Escobar-Briones, Adriana Gaytán-Caballero, Chieh-Wei Hsu, Markus Loher, Ian MacDonald, Yann Marcon, Thomas Pape, Miriam Römer, Maxim Rubin-Blum, Florence Schubotz, Daniel Smrzka, Gunter Wegener and Gerhard Bohrmann: Massive asphalt deposits, oil seepage, and gas venting support abundant chemosynthetic communities at the Campeche Knolls, southern Gulf of Mexico.
Published in: Biogeoscience, DOI: 10.5194/bg-13-4491-2016
Dr. Heiko Sahling
Telephone: 0421 218 65054
Further information / Photo material:
MARUM – Public Relations
Telephone: 0421 218 65540
Ulrike Prange | idw - Informationsdienst Wissenschaft
Global study of world's beaches shows threat to protected areas
19.07.2018 | NASA/Goddard Space Flight Center
NSF-supported researchers to present new results on hurricanes and other extreme events
19.07.2018 | National Science Foundation
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
19.07.2018 | Earth Sciences
19.07.2018 | Power and Electrical Engineering
19.07.2018 | Materials Sciences