Marine biologists have found adult tubeworms and other vent animals below the seafloor in the East Pacific Rise, a volcanically active, fast-spreading ridge with numerous hydrothermal vent fields.
Seafloor surface and crustal subseafloor vents at Fava Flow Suburbs, the East Pacific Rise. Image credit: Bright et al., doi: 10.1038/s41467-024-52631-9.
The East Pacific Rise is a volcanically active ridge located where two tectonic plates meet on the floor of the Pacific Ocean.
It contains numerous hydrothermal vents — openings in the seafloor that form where seawater and magma beneath the Earth’s crust meet.
“It was once believed that only microbes and viruses inhabited the subseafloor crust beneath hydrothermal vents,” said University of Vienna researchers Monika Bright and her colleagues.
“Yet, on the seafloor, animals like the giant tubeworm Riftia pachyptila thrive.”
“Their larvae are thought to disperse in the water column, despite never being observed there.”
“We hypothesized that these larvae travel through the subseafloor via vent fluids.”
Dr. Bright and co-authors, sailing on the Schmidt Ocean Institute research vessel Falkor (too), embarked on a series of dives to a hydrothermal vent site located at 2,515 m depth on the East Pacific Rise using the remotely operated vehicle SuB-astian.
When exposing sections of the seafloor crust using the arms of the vehicle, they uncovered warm, fluid-filled cavities inhabited by various species previously only found on the seafloor, including giant tubeworms and mobile animals such as worms and snails.
Larvae from seafloor communities may settle in these subseafloor habitats, indicating a complex connectivity between seafloor and subseafloor ecosystems.
The discovery of animal habitats in the crustal subseafloor, the extent of which is currently unknown, increases the urgency for protections against potential future environmental changes.
“The presence of adult tubeworms suggests larval dispersal through the recharge zone of the hydrothermal circulation system,” the authors said.
“Given that many of these animals are host to dense bacterial communities that oxidize reduced chemicals and fix carbon, the extension of animal habitats into the subseafloor has implications for local and regional geochemical flux measurements.”
“These findings underscore the need for protecting vents, as the extent of these habitats has yet to be fully ascertained.”
The team’s work appears in the journal Nature Communications.
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M. Bright et al. 2024. Animal life in the shallow subseafloor crust at deep-sea hydrothermal vents. Nat Commun 15, 8466; doi: 10.1038/s41467-024-52631-9
