Animal life in the shallow subseafloor crust at deep-sea hydrothermal vents
Nature Communications volume 15, Article number: 8466 (2024 ) Cite this article
It was once believed that only microbes and viruses inhabited the subseafloor crust beneath hydrothermal vents. 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. In our exploration, lifting lobate lava shelves revealed adult tubeworms and other vent animals in subseafloor cavities. The discovery of vent endemic animals below the visible seafloor shows that the seafloor and subseafloor faunal communities are connected. The presence of adult tubeworms suggests larval dispersal through the recharge zone of the hydrothermal circulation system. 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 East Pacific Rise (EPR) is a volcanically active, fast-spreading ridge with numerous hydrothermal vent fields1. The last two eruptions of the EPR segment near 9°50’N2 in 1991–19923 and 2005–20064 revealed a sequential megafauna colonization pattern at new vent fields from siboglinid tubeworms to bathymodiolin mussels5,6,7,8 thriving at distinct vent fluid regimes, and providing habitat for low diverse but biomass-rich animal communities6,9,10. Rapid colonization by these animals suggests efficient larval dispersal, with larvae assumed to be transported through bottom, ridge and ocean currents5,6,10,11,12,13,14 before they settle at vents through downwards swimming or sinking8,12,13.
