Effectiveness of methane-consuming bacteria in the ocean moderated by ocean currents

Ocean Currents Impact Methane consumption

Study in Nature Geoscience on interactions between marine microbiology and oceanography

It can be clearly seen, how the current differs above the methane seeps (blue square). Simulation and visualization: GEOMAR.

It can be clearly seen, how the current differs above the methane seeps (blue square). Simulation and visualization: GEOMAR.

Offshore the Norwegian Svalbard archipelago, methane gas is seeping out of the seabed in several hundred meters depth. Luckily, bacteria are consuming a large proportion of the methane before it reaches the surface and is released to the atmosphere, where it acts as a greenhouse gas. An interdisciplinary study conducted by researchers at the University of Basel and the GEOMAR Helmholtz Centre for Ocean Research Kiel could now show that ocean currents can have a strong impact on methane removal. The renowned journal Nature Geoscience has published the study.

Joint press release of the University of Basel and the GEOMAR Helmholtz Centre for Ocean Research Kiel

Large amounts of methane – whether as free gas or as solid gas hydrates – can be found in the sea floor along the ocean shores. When the hydrates dissolve or when the gas finds pathways in the sea floor to ascend, the methane can be released into the water and rise to the surface. Once emitted into the atmosphere, it acts as a very potent greenhouse gas twenty times stronger than carbon dioxide. Fortunately, marine bacteria exist that consume part of the methane before it reaches the water surface. Geomicrobiologists and oceanographers from Switzerland, Germany, Great Britain and the U.S. were able to show in an interdisciplinary study that ocean currents can have a strong impact on this bacterial methane removal. The international scientific journal Nature Geoscience has published the study.

The data was collected during an expedition in the summer of 2012 aboard the research vessel MARIA S. MERIAN. At that time, the international research team was studying the methane seeps off the west coast of the Norwegian Svalbard archipelago. “Already then, we were able to see that the level of activity of the methane consuming bacteria changed drastically over very short time spans, while at the same time many oceanographic parameters such as water temperature and salinity also changed”, explains Lea Steinle, first-author of the study and PhD student at the University of Basel and the GEOMAR Helmholtz Centre for Ocean Research Kiel. For her PhD thesis, Steinle studies where and how much methane is consumed in the ocean water column by bacteria.

In order to test if the fluctuations measured during the four weeks of the expedition were only random observations or based on typical and recurring processes, oceanographers of the GEOMAR later took a closer look at the region with a high resolution ocean model. “We were able to see that the observed fluctuations of the oceanographic data and the activity level of the bacteria can be traced back to recurring shifts in the West Spitsbergen Current”, says Prof. Dr. Arne Biastoch from the GEOMAR. The West Spitsbergen Current is a relatively warm, salty current that carries water from the Norwegian Sea to the Arctic Ocean. “It mostly runs very close to the coast. Shifts in the current strength are responsible for the meandering of the current. Then, in a matter of a few days, the current moves miles away from the coast”, explains Professor Biastoch further.

If the current runs directly over the methane seeps near the coast or continues on the open sea, impacts the methane filtration. “We were able to show that strength and variability of ocean currents control the prevalence of methanotrophic bacteria”, says Lea Steinle, ”therefore, large bacteria populations cannot develop in a strong current, which consequently leads to less methane consumption.”

In order to verify if these results are only valid for Spitsbergen or are of global importance, the researchers studied in a second, global ocean model how ocean currents are varying in other regions of the world with methane seeps. “We saw that strong and fluctuating currents are often found above methane seeps”, says Dr. Helge Niemann, biogeochemist at the University of Basel and one of the initiator of the study. His colleague Prof. Dr. Tina Treude, geomicrobiologist at the University of California Los Angeles adds: “This clearly shows that one-time or short-term measurements often only give us a snapshot of the whole situation.” In the future, fluctuations of bacterial methane consumption caused by oceanographic parameters will have to be considered, both during field measurements as well as models.


Reference:
Steinle, L., C. A. Graves, T. Treude, B. Ferré, A. Biastoch, I. Bussmann, C. Berndt, S. Krastel, R. H. James, E. Behrens, C. W. Böning, J. Greinert, C.-J. Sapart, M. Scheinert, S. Sommer, M. F. Lehmann, H. Niemann (2015): Water column methanotrophy controlled by a rapid oceanographic switch. Nature Geoscience, http://dx.doi.org/10.1038/ngeo2420

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25 thoughts on “Effectiveness of methane-consuming bacteria in the ocean moderated by ocean currents

    • Archaea and bacteria which consume methane differ, but for some the waste product is S.

    • In the case here, they poop CO₂.
      Methanotrophs consume methane as their energy source, they may be in aerobic or anaerobic environments.
      In the case here, the water column has dissolved oxygen, the bacteria eat CH₄, they poop CO₂. And oxygen is the final electron acceptor, making water.

      Obligate anaerobic metabolism of methane is more complex and not well understood, but probably needs cooperative from different classes of microbes, and sulfur is involved. This probably occur in oxygen depleted sediments and the ancient oceans before dissolved oxygen became available in seawater.

      Do not confuse methanotrophs (eating methane) with methanogens (producing methane). Methanogens live in oxygen depleted environments, like in the gut, and turn complex biomass into methane, rpodiucing electrons along the way.

  1. Nature Geoscience is not Nature Climate Science.
    It is a respectable journal with a track record of publishing papers that aren’t immediately refuted.

    I don’t know about this paper but there is no reason to not deign to engage with it.

    • Sorry but this statement indirectly ties it to “climate change”:
      “Once emitted into the atmosphere, it acts as a very potent greenhouse gas twenty times stronger than carbon dioxide.”

      • That is a true statement. But for very few years, since residence time is low. It oxidizes to one part CO2 and two parts water. Sunlight catalysis. Read up on this.

    • What is there to engage? It is simply an acknowledgement that there is bacteria that consume methane and a plea for more money to study them. Everything else is unfounded speculation as the paper admits: we don’t know how wind effects them but there MIGHT be a relation in global oceans; however, we KNOW it is important to “climate change” and MUST be included in “models.”

  2. Sounds like there is an inorganic source for carbon on Earth. A bit like in the Mars. According to NASA CO2 mass on Mars is several times that on Earth. And yet, they report carbon dioxide clouds, snow and even dry ice on Mars. Some water too. Sun’s rays arrive full blast, but the warming positive feed-backs are elusive. Tough Martian luck, I guess.

    Oh well. The Earth doesn’t have a firmament like a greenhouse, but luckily there is a magnetosphere protecting us from Sun’s radiation and an atmosphere between us and space at about -270°C.

    • No. Svalbard even has mined coal deposits. At one point in the geological past it was located for a long time near the equatorial tropics. Lindzen himself grilled me on this when we met in person for a day to review the climate chapter of The Arts of Truth. Deliberately buried in long footnote #5. The now accepted 600my continental drift of Svalbard is shown there in detail.

  3. This is really interesting and very good paper, but including for reasons not in the abstract. Possibly because the Svalbard seeps do not show the most interesting biological part so much.
    The data comes from the aftermath of the BP Macondo blowout, which suddenly produced massive amounts of both oil and gas at depth in the Gulf of Mexico without much of a current. (It was the massive methane forming ice clathrate that plugged up the massive ‘bell’ that was BP’s first failed attempt to contain and control the blowout).
    Some oil reached the surface despite extensive use of dispersants, and despite the presence of ‘oil eating’ bacteria (shown by water column sampling, those bacteria possibly harmed by the dispersants). Why? Because oil forms droplets that take time for bacteria to chew through starting on the outside.

    Almost no methane reached the surface. Why? Because of explosive growth of methanotroph bacteria in the water column given new abundance of a food source. Dissolved methane does not clump into droplets, and its seafloor bubbles dissolve and disperse as they ascend the water column.
    The biological responses of Earth’s microbiota are no where near well enough understood.

  4. A picture is worth a 1,000 words:

    Any scientist that still advocates CH4 as a possible existential threat should lose his tenure.

    Reality simply doesn’t support CAGW’s CH4 wild projections; not even close.

  5. If we use a “Submarine Methane Collector” (SUMEco) device to collect and transport some of the seeping meethane – we can use this renewable resource? (see researchgate.net for details on the contraption).

  6. Do you mean ‘methane-consuming bacteria’ (i.e., the bacteria are doing the consuming) or ‘methane consuming bacteria’ (the opposite)?

    [Fixed, thanks. ~mod.]

  7. “”Once emitted into the atmosphere, it acts as a very potent greenhouse gas twenty times stronger than carbon dioxide.””
    Really?? How??
    Look up the emissivity of methane and put the numbers into the longest IR wavelength methane can emit over and you will find the temperature needs to be around 100C!!!!!! Please tell me where you will find that temperature in our atmosphere. Methane can absorb sunlight but once those sunlight photons are absorbed they can’t warm the surface. If methane could emit all it absorbed only half would reach the surface. A cooling effect like all the other ‘greenhouse gases’. Over night methane absorbs NOTHING from the surface. Just how does this magical back radiation take place????

    • “Methane can absorb sunlight but once those sunlight photons are absorbed they can’t warm the surface.” Part of climate change is not just surface warming but atmosphere warming. Warming the atmosphere reduces the amount of radiated energy that can reflect back into space.

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