Microbes make the methane soldier. But may not do that soon enough.

A methane leak is a place where methane seeps from the ocean floor. Researchers worldwide have already discovered several of these types of methane leaks. But that these also occur in Antarctica; we had no hard evidence for that. Researchers have now encountered an active methane leak in the Ross Sea near Antarctica for the first time. And while it seems that microbes have taken care of the methane leak, some of this percolating greenhouse gas may still enter the atmosphere.

More about methane

Methane is mainly known to us as an important greenhouse gas. In fact, after carbon dioxide, methane is the most important greenhouse gas that contributes to global warming. For example, methane is responsible for twenty to thirty percent of the rising temperatures. Although the gas is less present on Earth than CO2, it is much more powerful; as a greenhouse gas it is even 25 times stronger. Most of the methane that resides in ocean water or sediments is kept out of the atmosphere by microbes that like to feast on it.

The researchers discovered the leak in an area that has been studied by scientists for more than sixty years. “However, the leak did not become active until 2011,” said researcher Andrew Thurber. In 2012, the researcher was pointed out to a so-called ‘microbial waterfall’ by another scientist, after which Thurber decided to study it further. The researcher found a microbial mat about 70 meters long and one meter wide on the sea floor, about ten meters below the frozen ocean surface. “This mat is an important indication that methane is seeping out here,” Thurber explains. In addition, when Thurber returned a few years later, in 2016, he discovered a second leak nearby.

These white microbial mats and the presence of starfish are important indications that methane seeps from the ocean floor at this location.
Image: Andrew Thurber, Oregon State University

Microbes
The researchers decided to thoroughly inspect the microbes on site. Over a five-year span, the researchers closely monitored how the microbes responded to the formation of the methane leak. And here came a surprising discovery. “We found that the microbial community was not developing in the same way that we predicted from other methane leaks around the world,” said researcher Sarah Seabrook. The researchers had thought that microbes would react very quickly to changes in the environment, but nothing could be further from the truth. They discovered that it took a while for the microbes to take action. “And even then, they didn’t consume all the methane present,” says Thurber.

Differences
But that was not the only surprising thing. For example, it appears that the microbes are very different from the microbes around other methane leaks. “To further increase the mystery, we found that the microbes found were not among the species we expected,” said Thurber. “Different types of microbes may follow each other, with certain groups arriving first and the microbes that eat the most methane appear later.” But the researcher also has another theory. “Animals in Antarctica are very different from elsewhere, as the continent has been separated from the rest of the world for more than 30 million years,” he says. “This has resulted in a remarkable diversity of fauna that we only find here. And that may also have contributed to the differences in microbes. ”

Antarctica
According to the researchers, it is very important to gain insight into the seeping methane in Antarctica. The area contains a whopping 25 percent of all the Earth’s marine methane. “Antarctica has huge reservoirs that are likely to open as ice caps retreat due to climate change,” said Thurber. “This is an important discovery that can help fill a large gap in our understanding of the methane cycle.” It means that it is quite possible that more methane leaks will occur in Antarctica. It is therefore very important that researchers now have the opportunity to study an active leak. This can provide more insight into the local methane cycle and how this process differs in Antarctica compared to other places on our planet.

The research therefore yields interesting and important findings . “Until now, we have never had the opportunity to investigate a methane leak in Antarctica,” said Thurber. “But because of this discovery, we can now study whether these types of leaks on the continent simply work differently, or whether it takes years for microbial communities to adapt.” Ultimately, this information can also help to achieve new climate change models. The last word has therefore certainly not yet been said. Thurber hopes to return to the area in the future to monitor developments and conduct further research.

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