The carbon dioxide is mostly in the centre of the climate change discussions, but also another greenhouse gas that makes the world in a fever: methane has much less in the atmosphere, it has a roughly 25-fold stronger greenhouse effect than carbon dioxide. In addition to its anthropogenic release of natural sources of this gas are well-known: It rises from deposits of organic material and also from the sea. There it flows from so-called “cold springs” that are located in great Depths on the sea floor. Fortunately, only a part of the emitted methane reaching the surface, because it is already caught in the deep by living beings.

It is already known that the sources of Methane forming veritable oasis in the “desert” of the deep sea. The basis of the communities of bacteria that can utilize methane as a food to biomass build up form. They live freely in the water or real mats at the bottom. You have an illustrious community of other living organisms – from the worm eats up the crab. There are also a few animals are not, however, known that these microbes eat, but with you in partnership to life: There are mussels, sponges, and worms, which provide the microbes in or on their bodies a home. In return, the bacteria provide you with food that comes from the methane removal. These symbiotic organisms have added to the scientists to Shana Goffredi from Occidental College in Los Angeles now, two new representatives, which may be of great importance to the methane removal in the area of cold springs is coming.

symbiosis or not?

In the course of their studies of communities around sources of Methane in the deep sea, two representatives of the tube-worms and are sent into the visor of the researchers. It was, according to them, that they occur worldwide in the environment to cold sources often. One of the two species belongs to the genus lamina tube, the other to the Bispira. They are living beings sitting in the tubes, and whose Opening spring-like structures into the water lines. So far, it was assumed that the tube worms to fish with these formations to methane-oxidizing bacteria in the area of cold springs and as a feed to incorporate. In the context of their study Goffredi and her colleagues have investigated the suspicion that these worms live instead in symbiosis with the bacteria – that is, of them are inhabited.

The researchers raised the animals specimens by diving to methane sources located at a depth of 1768 to 1887 meters off the coast of Costa Rica. On Board the research vessel, the living worms were kept in special containers. In order to examine whether or not they consume methane (CH4), supplied the scientists with a marked Version of the substance containing the carbon isotope C13. As they report, they found after incubation with the labeled methane in the basin of water, carbon dioxide enriched with carbon-13. This means that The worms and their bacterial partners had processed the methane. Subsequent studies confirmed that the carbon was transferred 13 from methane into the biomass of the worms.

climate-relevant deep-sea dwellers

By microscopic investigations, the scientists were then also the methane-oxidizing bacteria on the track. It is therefore representatives from the group of Methylococcales, which exist in the spring-like structures of the tube worms. There life is protected and may collect methane from the water. How exactly do the worms get the nutrients from their symbiotic partners, is not yet entirely clear. However, there are indications that the cells of the worms to absorb some of the bacteria and digest. But it is also possible that there is a Transfer of energy-rich substances by the microbes to their partners.

“The two worm species so well in the small group of animals, which are known is that they live closely together with methane-oxidizing bacteria”, the researchers write. Among these organisms, the tube worms could occupy a particularly important position, as a further result of the study. When exploring the area of cold springs off the Pacific coast of Costa Rica, the scientists found that The worms cover large areas of the sources of Methane and up to 300 metres further away from you than other organisms of these deep-sea oases. Therefore, you may use also appears to lower methane concentrations in the environment.

The scientists assume that the tube worms to play this role at other methane sources in the world. According to them, the question of how one defines the boundaries of the areas of these Ecosystems therefore. If you want to get the methane removal potential of these deep-sea inhabitants, account should be taken of their possibly large spread. So you could keep the communities of cold springs against damage caused by deep-sea fisheries and oil production, the researchers say.

source: Science Advances, doi:

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