An international team of scientists led by researchers from the Arctic University of Norway (UiT) has discovered a previously unknown deep-sea ecosystem of extreme lifeforms thriving on the Arctic seafloor near the deepest gas hydrate cold seep ever found.
Spotted during the Ocean Census Arctic Deep–EXTREME24 expedition at a depth of 3,640 meters on Molloy Ridge in the Greenland Sea, the gas hydrate mounds—labeled Freya Hydrate Mounds—could assist conservation efforts and have direct implications on the Arctic governance and sustainable development of the region.
The discovery of the complex and diverse ecosystem surrounding the mounds could offer previously unavailable insights into the extreme organisms, sometimes called extremophiles, that many scientists suspect may already exist in similar deep-sea extraterrestrial environments such as the subsurface oceans of Jupiter’s moon Europa and Saturn’s moon Enceladus.
“We found an ultra-deep system that is both geologically dynamic and biologically rich, with implications for biodiversity, climate processes, and future stewardship of the High North,” explained the Chief Scientist of the expedition, UiT Professor Giuliana Panieri.
Arctic Seafloor Hosts Thriving Deep-Sea Ecosystem of Extremophiles
According to a statement detailing the pair of discoveries, the Ocean Census Arctic Deep – EXTREME24 expedition brought together leading experts in geology, biology, and geochemistry to study the complex dynamics of this deep-sea environment. This included the collection of high-resolution imagery and ROV-collected samples gathered over 10,000 feet below the surface in the icy Arctic waters.
During the expedition, the team spotted methane gas “flares” rising in a column more than 3,300 meters through the water. Among the tallest such phenomena ever found anywhere in the world, it hinted at complex activity and the likely presence of Freya Hydrate Mounds on the ocean floor.
According to Professor Panieri, who is also the Director of CNR-ISP and a co-author of the study, these deposits, found at a staggering depth of 3,640 meters, “greatly surpass” the typical depths of such mounds, which are less than 2,000 meters. The professor noted that these findings challenge our previous understanding of hydrate formation, offering an opportunity to explore these environments further.
In the statement, the team said a closer examination of thermogenic gas and crude oil samples collected by the ROV at the ocean floor site revealed a complex history of deep geological fluid migrations “that reflect the intricate interactions between geological formations over time.”
“In this regard, the Freya mounds represent an ultra-deep natural laboratory for studying methane behaviour in the water column and the potential impacts of warmer waters in the Fram Strait,” they explained.
Discovery “Rewrites the Playbook” for Arctic Deep-Sea Ecosystems
For example, an initial analysis suggested that deep-sea hydrate mounds form, destabilize, and ultimately collapse over time. Following direct ROV observations, this hypothesis was proven to be accurate. The deep-sea hydrate seeps that provide energy and nutrients to these extreme life forms create a complex and dynamic environment where they grow, thrive, and then collapse due to external forces.
“These are not static deposits,” Panieri explained. “They are living geological features, responding to tectonics, deep heat flow, and environmental change.”
A closer analysis of the lifeforms living and thriving in this complex ecosystem found that the site was dominated by specialized organisms adapted to the extreme local environment. This included amphipods, snails, and tubeworms.
The team noted that this biological diversity “highlights the unique adaptations of life forms in this extreme environment.” It revealed a substantial overlap with complex ecosystems found around deep-sea hydrothermal vents. They also noted that this expedition revealed a “previously unrecognized level” of connectivity between diverse ecosystems across deep-sea Arctic habitats.
“This discovery rewrites the playbook for Arctic deep-sea ecosystems and carbon cycling,” Panieri said.
Resource Exploitation, Habitat Conservation, and the Search for Life
When discussing potential implications of the discovery, Jon Copley of the University of Southampton, UK, who led the study’s biogeographic analysis, said there are likely more deep-sea gas hydrate mounds “awaiting discovery” in the region. The researcher also noted that the types of marine life thriving around the Freya mounds “may be critical in contributing to the biodiversity of the deep Arctic.”
“The links that we have found between life at this seep and hydrothermal vents in the Arctic indicate that these island-like habitats on the ocean floor will need to be protected from any future impacts of deep-sea mining in the region,” Copley explained.
Panieri agreed, noting that the issue is pressing since the area they studied is increasingly under evaluation for resource exploitation.
“Understanding these unique habitats is essential for safeguarding biodiversity and supporting responsible decision-making in polar regions,” he explained.
The discovery also has potential implications for astrobiologists searching for specialized lifeforms living in extreme deep-sea environments. These include potential future missions designed to explore the suspected subsurface oceans of Enceladus and Europa, and other solar-system moons that may host complex biological communities dependent on the energy and nutrients provided by deep-sea ecological activities such as hydrothermal vents and hydrate seeps.
The study, “Deep-sea gas hydrate mounds and chemosynthetic fauna discovered at 3640 m on the Molloy Ridge, Greenland Sea,” was published in Nature Communications.
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.