Underground Ecosystem More Diverse Than Life on The Surface

A ten year study has discovered a rich world of microbes living deep under the Earth's surface.
Jessica Miley

Scientists have discovered a whole new world of organisms living deep below the surface of the earth.

The subteranem biosphere reportedly contains between 15bn and 23bn tonnes of microorganisms, hundreds of times the combined weight of every human on the planet. 

The discovery is a result of a ten-year-long long study completed by the Deep Carbon Observatory to ‘understand the quantities, movements, forms, and origins of carbon inside Earth’.

The Observatory says that despite intense underground conditions including immense pressure and heat, they have discovered evidence of bacteria, archaea, and other microbes 5000 metres below the surface of the earth.

Underground Ecosystem More Diverse Than Life on The Surface
Source: Deep Carbon

An international group of scientists combined data from the global investigation 

Scientists in the long-term study drilled several kilometres into the seafloor and collected samples from continental mines more than 5 km deep to formulate their results that will be presented at the American Geophysical Union’s annual meeting, taking place 10-14 December.

The collaborative group of researchers was able to combine the data from hundreds of sites across the globe to create a list of findings that have a huge impact on the way we understand the earth. 

The group has approximated the ‘size of the deep biosphere to be 2 to 2.3 billion cubic km (almost twice the volume of all oceans). 

They also estimate the carbon mass of deep life to be 15 to 23 billion tonnes (an average of at least 7.5 tonnes of carbon per cu km subsurface).

Underground Ecosystem More Diverse Than Life on The Surface
Source: Deep Carbon

Life underground more diverse than expected

The scientists say the the research area, earths deep biosphere, can be thought of as a sort of ‘“subterranean Galapagos” and contains all three domains of life:bacteria and archaea (microbes with no membrane-bound nucleus), and eukarya (microbes or multicellular organisms with cells that contain a nucleus as well as membrane-bound organelles).’

 The study shows that there are millions of types of bacteria and archaea that are yet to be discovered or fully classified and that as much as 70% of Earth's bacteria and archaea live in the subsurface.

These underground microbes are also vastly different from their surface-dwelling relatives. 

Underground Ecosystem More Diverse Than Life on The Surface
Source: Deep Carbon

Study sheds light on carbon stores

The subterranean microbes have vastly longer life cycles and in some cases consume only energy from rocks. Amazingly the variety of life discovered underground rivals or possibly even surpassed the diversity experienced on the surface. 

In addition to expanding the scientific understanding of the deep biosphere, the decade-long project also casts new light on the impact of life in subsurface locations that has been manipulated by humans through interventions such as fracked shales. 

Underground Ecosystem More Diverse Than Life on The Surface
Source: Deep Carbon

“Exploring the deep subsurface is akin to exploring the Amazon rainforest. There is life everywhere, and everywhere there’s an awe-inspiring abundance of unexpected and unusual organisms,” says Mitch Sogin of the Marine Biological Laboratory Woods Hole, USA, co-chair of DCO’s Deep Life community of more than 300 researchers in 34 countries. 

“Molecular studies raise the likelihood that microbial dark matter is much more diverse than what we currently know it to be, and the deepest branching lineages challenge the three-domain concept introduced by Carl Woese in 1977.

Perhaps we are approaching a nexus where the earliest possible branching patterns might be accessible through deep life investigation.”

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