Large communities of bacteria in the Mariana Trench

Deep sea trenches act as hot spots for microbial activity because they receive an unusually high flux of organic matter, made up of dead animals, algae and other microbes, sourced from the surrounding much shallower sea-bottom.

An international research team announces the first scientific results from one of the most inaccessible places on Earth: the bottom of the Mariana Trench located nearly 11 kilometers below sea level in the western Pacific, which makes it the deepest site on Earth.

Their analyses document that a highly active bacteria community exists in the sediment of the trench - even though the environment is under extreme pressure almost 1,100 times higher than at sea level.

In fact, the trench sediments house almost 10 times more bacteria than in the sediments of the surrounding abyssal plain at much shallower water depth of 5-6 km water.

Deep sea trenches are hot spots
Deep sea trenches act as hot spots for microbial activity because they receive an unusually high flux of organic matter, made up of dead animals, algae and other microbes, sourced from the surrounding much shallower sea-bottom.

It is likely that some of this material becomes dislodged from the shallower depths during earthquakes, which are common in the area.

So, even though deep sea trenches like the Mariana Trench only amount to about two percent of the World Ocean area, they have a relatively larger impact on marine carbon balance - and thus on the global carbon cycle, says Professor Ronnie Glud from Nordic Center for Earth Evolution at the University of Southern Denmark.

Ronnie Glud and researchers from Germany (HGF-MPG Research Group on Deep-Sea Ecology and Technology of the Max Planck Institute in Bremen, Scotland's (Scottish Association for Marine Science), Japan's (Japan Agency for Marine-Earth Science and Technology),  and Denmark (University of Copenhagen), explore the deepest parts of the oceans, and the team's first results from these extreme environments were published in the widely recognized international journal Nature Geoscience.