The deepest oceanic site on Earth is home to a surprisingly active microbial community, reports a study published online in Nature Geoscience this week. The microbes in this Pacific seafloor setting seem to be fuelled by relatively high levels of sediment deposition.

Ronnie Glud and colleagues monitored microbial activity, in the form of oxygen consumption, in seafloor sediments in Mariana Trench, an 11,000-metre-deep trench at the bottom of the central west Pacific Ocean. They discovered high rates of oxygen consumption, indicative of an actively respiring microbial community whose activity exceeds two-fold that of a nearby 6,000-metre-deep site.

In an accompanying News and Views article, Eric Epping says “measurements at Mariana Trench point to an unexpectedly active microbial community in the deepest seafloor setting on the planet”