A recent underwater expedition has revealed a thriving network of creatures at the bottom of deep-sea ocean trenches. These extreme environments, with crushing pressure, scant food, and no sunlight, pose immense survival challenges. While tiny microbes are known to prosper, evidence of larger marine life has been scarce.
Using a submersible, researchers exploring the Kuril–Kamchatka and Aleutian trenches in the northwest Pacific found tubeworms and molluscs flourishing over 31,000 feet (9.5 kilometres) deep. The ocean's deepest point is approximately 36,000 feet (11 kilometres).
Scientists had surveyed this area before and had hints that larger creatures might live at such depths. The new discovery confirms those suspicions and shows just how extensive the communities are, said Julie Huber, a deep sea microbiologist with Woods Hole Oceanographic Institution.
“Look how many there are, look how deep they are," said Huber, who was not involved with the research. “They don't all look the same and they're in a place that we haven't had good access to before.”
The findings were published Wednesday in the journal Nature.
In the absence of light to make their own food, many trench-dwellers big and small survive on key elements like carbon that trickle down from higher in the ocean.
Scientists think microbes in this new network may instead be capitalizing on carbon that's accumulated in the trench over time, processing it to create chemicals that seep through cracks in the ocean floor. The tubeworms and mollusks may survive by eating those tiny creatures or living with them and snacking on the products of their labor, scientists said.
With this discovery, future studies will focus on how these deep-sea creatures adapted to survive in such extreme conditions and how exactly they harness chemical reactions for food, study authors Mengran Du with the Chinese Academy of Sciences and Vladimir Mordukhovich with the Russian Academy of Sciences said in a statement.
Their existence challenges “long-standing assumptions about life's potential at extreme depths,” the authors said.
