Microbes are thriving in surprising numbers at the deepest spot in the oceans, the 11,000-meter Mariana Trench in the Pacific, despite crushing pressures in sunless waters, scientists said.
Dead plants and fish were falling as food for microscopic bugs even to the little-known hadal depths, parts of the seabed deeper than 6,000m and named after Hades, the god of the underworld in Greek mythology, they said.
The presence of life in the trench also shows how the greenhouse gas carbon dioxide can eventually get buried in the depths in a natural process that slows climate change.
A Danish-led team of scientists, using a robot to take samples, found double the amount of bacteria and other microbes munching away on debris at the bottom of the Mariana Trench in the western Pacific than at a nearby site 6,000m deep.
“It’s surprising there was so much bacterial activity,” said Ronnie Glud, of the University of Southern Denmark. “Normally life gets scarcer the deeper you go. But when you go very deep, more things start happening again,” he said.
The finding backed up a theory that dead plants and fish falling onto the steep sides of the Mariana Trench often slide to the bottom to form a “hot spot” for microbes.