The Freya Hydrate Mounds Lie Over 11,940 Feet Below the Surface — and They’re Teeming With Life

About 11,942 feet (3,640 meters) below the surface of the Greenland Sea, methane regularly escapes from the seafloor. Along the Molloy Ridge, gas bubbles rise through the water column, oil leaks from buried sediments, and groups of animals congregate in complete darkness, feeding on chemicals rather than sunlight.

The site, known as the Freya Hydrate Mounds, lies deeper than any previously documented cold gas hydrate seep. Images from remotely operated vehicles show methane and oil seeping from the seabed, surrounded by dense communities of animals living without sunlight. Described in Natural communicationsThe discovery pushes known hydrate systems nearly 5,905 feet (about 1,800 meters) deeper than previously thought and links this seep to life typically found in Arctic hydrothermal vents.

“This discovery rewrites the model of Arctic deep-sea ecosystems and the carbon cycle,” said Giuliana Panieri, the expedition’s chief scientist, in a press release. “We have discovered an ultra-deep system that is both geologically dynamic and biologically rich, with implications for biodiversity, climate processes and the future management of the High North. »

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A deep-sea system that continues to change

What sets Freya Hydrate Mounds apart is not only their depth but also their apparent activity. Images of the seafloor show the mounds in different states – some intact, others broken down – suggesting the system is constantly evolving rather than frozen.

Chemical evidence helps explain what is causing this change. The methane released at the site formed deep underground, rather than being produced by microbes near the seafloor. Crude oil samples point to a source millions of years old, indicating that fluids moved slowly upward through the Earth’s crust over long periods of time. This regular movement appears to both build and destabilize the hydrate mounds.

One of the clearest signs of this activity is how far the methane travels. Gas flares have been observed rising more than 10,826 feet (about 3,300 meters) through the water column – among the highest on record – carrying carbon from the depths of the sea floor to the ocean above.

“These are not static repositories,” Panieri said. “They are living geological features, responding to tectonics, deep heat flows and environmental changes. »

What Freya’s hydrate mounds could mean for the future of the Arctic

Beyond biology, the Freya Hydrate Mounds offer scientists a rare window into the behavior of methane at extreme depths. The site provides an ultra-deep setting to study how gas moves from buried geologic sources to the ocean, particularly in Fram Strait, where changing ocean conditions can influence hydrate stability. Seafloor observations indicate that hydrate structures form, destabilize, and collapse over time, highlighting the dynamic role these systems play in the Arctic carbon cycle.

The same conditions that allow methane to escape from the seabed also support life. At the site, researchers documented chemosynthetic communities living alongside active seeps – an unusual combination at such depth. When the team compared these communities to those found elsewhere in the Arctic, they found a notable overlap with animals living near hydrothermal vents. According to the researchers, this similarity suggests that ultra-deep cold seeps could contribute to the biodiversity of the deep Arctic.

“It is likely that there are other very deep cold gas hydrate seeps, like the Freya Mounds, awaiting discovery in the region, and the marine life that thrives around them could be key to contributing to the biodiversity of the deep Arctic,” Jon Copley, who led the biogeographic analysis, said in the press release.

“The connections we found between life in this seep and Arctic hydrothermal vents indicate that these island habitats on the ocean floor will need to be protected from any future impacts of deep-sea mining in the region,” Copley concluded.

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