Microbial life may exist far deeper in the ocean floor than is often assumed.

Steven D'Hondt at the University of Rhode Island in Narragansett and his colleagues sampled sediments across the southern Pacific Ocean. They found that oxygen, and microbes that require it, permeated depths of up to 75 metres below the sea floor — more than double previous estimates.

The team found that oxygen penetrates the entire sediment column where the sediment accumulates slowly in a shallow layer. On this basis, the authors estimate that microbes that use oxygen may exist at low, but measurable, amounts throughout sediment in around 15–44% of the Pacific and in 9–37% of the global sea floor.

Nature Geosci. http://dx.doi.org/10.1038/ngeo2387 (2015)