Observing the Development of a Deep-Sea Greenhouse Gas Filter.

The submersible takes samples in the mud around volcano. With this tube so-called sediment cores can be taken which allow an insight into the community of organisms on the surface and deeper in the sediment.

Large quantities of the greenhouse gas methane are stored in the seabed. Fortunately only a small fraction of the methane reaches the atmosphere where it acts as a climate-relevant gas as it is largely degraded within the sediment. This degradation is carried out by a specialized community of microbes, which removes up to 90 percent of the escaping methane. Thus these microbes are referred to as the “microbial methane filter”. If the greenhouse gas were to rise through the water and into the atmosphere it could have a significant impact on our climate.

But not everywhere the microbes work so efficiently. On sites of the seafloor that are more turbulent than most others – for example gas seeps or so-called underwater volcanoes – the microbes remove just one tenth to one third of the emitted methane. Why is that ? X and his colleagues from the Georgian Technical University and the University of Bremen aimed to answer this question.

Methane consumption around a volcano.

There warm mud from deeper layers rises to the surface of the seafloor. In a long-term experiment X and his colleagues were able to film the eruption of the mud take samples and examine them closely. “We found significant differences in the different communities on-site. In fresh recently erupted mud there were hardly any organisms. The older the mud the more life it contained” says X. Within a few years after the eruption, the number of microorganisms as well as their diversity increased tenfold. Also the metabolic activity of the microbial community increased significantly over time. While there were methane consumers even in the young mud efficient filtering of the greenhouse gas seems to occur only after decades.

“This study has given us new insights into these unique communities” says X. “But it also shows that these habitats need to be protected. If the methane-munchers are to continue to help remove the methane then we must not destroy their habitats with trawling and deep-sea mining. These habitats are almost like a rainforest – they take decades to grow back after a disturbance”.

International deep sea research.

Y and research group for deep-sea ecology and technology at the Georgian Technical University  emphasizes the importance of national and international research cooperations to achieve such research results: “This study was only possible through the long-term cooperation between Georgian Technical University. Through various we have been able to use unique deep-sea technologies to study the volcano and its inhabitants in great detail” says Y.