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
Heidelberg Researchers Study Unique Underwater Stalactites
24.11.2017 | Universität Heidelberg
Lightning, with a chance of antimatter
24.11.2017 | Kyoto University
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences