Deepwater tube worms benefit from methane-eating bacteria


Scientists exploring deep seepage, where methane bubbles emerge from the seabed, have made a discovery that changes our understanding of these mysterious ecosystems. They discovered that two tube worm species capture methane, a powerful greenhouse gas, thanks to an unprecedented symbiotic relationship between worms and methane-eating bacteria.

By mapping the seabed near Costa Rica with autonomous underwater vehicles, the scientists also realized that these worms were disseminated up to 300 meters further from the methane seeps than other organisms. Their research, published today in the journal Scientists progress, could strengthen the arguments for extending the limits used to protect the ecosystems around methane seeps deep drilling and mining.

“It is really important for the health of the earth, these ecosystems. Literally every time we are on the high seas with a submersible and collect things, we discover a new species, “said Shana Goffredi, lead author of the study and biologist at Occidental College. “There are so many things out there that we don’t know yet and it would be a shame to lose them. “

What first caught the attention of the researchers was that the tube worms at this particular location – a methane ooze called Jaco Scar – had “a sort of softer appearance,” according to Goffredi. Sometimes when animals associate with bacteria living on their bodies, they can look “fluffy” or “hairy,” said Goffredi. Until now, bacteria that feed on the methane released by these seeps were not known to live on the bodies of oceanic invertebrates like worms. She and her colleagues brought the worms to their ships and discovered that the two species understood how to grow the bacteria living on their bodies as a source of nutrition.

“It’s like having your own type of photosynthesis, but instead of using light energy, they use methane as an energy source,” said Victoria Orphan, co-author and geobiologist at the California Institute of Technology. The process breaks down the methane, possibly preventing it from going up into the atmosphere. “It is a really smart strategy for animals in these environments to team up with microorganisms because they are truly the champion chemists in these habitats,” she said. Orphan and Goffredi believe similar worms surrounding methane seeps around the world are likely to do the same.

According to some estimates, the life surrounding these seeps prevents up to 90% of the methane escaping from the seabed from reaching the atmosphere and heating our planet. It is still unclear to what extent these worms play a role in relation to the free bacteria known to prevent much of the greenhouse gases from escaping from the ocean. But the researchers point out that damaging these ecosystems by mining and drilling on the high seas before understanding them could have far-reaching effects.

“Many of these systems, like the Amazon, are poorly understood and we are still learning about the value of these resources. Our scientists are sort of in this race to at least establish a reference base to better inform conservation efforts, ”explains Orphan. ” Even if [this ecosystem is] remotely, this does not necessarily mean that there is no connection with us. ”


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