The COVID-19 pandemic is a stark reminder that we move through a world shaped by unseen life. Bacteria, viruses, and other microscopic organisms regulate the Earth's vital functions and resources, from the air we breathe to all our food and most of our energy sources.

An estimated one-third of the Earth's microbes are literally hidden, buried in sediments deep below the ocean floor. Now, scientists have shown that these "deep biosphere" microbes aren't staying put but are bubbling up to the ocean floor along with fluids from buried petroleum reservoirs. These hitchhikers in petroleum seeps are diversifying the microbial community that thrives at the seafloor, impacting deep-sea processes, such as carbon cycling, that have global implications.

"This study confirms that petroleum seeps are a conduit for transporting life from the deep biosphere to the seafloor," says co-author Emil Ruff, a scientist at the Marine Biological Laboratory (MBL), Woods Hole. The study, led by Anirban Chakraborty and Casey Hubert of the University of Calgary, is published this week in Proceedings of the National Academy of Sciences.

The team analyzed 172 seafloor sediment samples from the eastern Gulf of Mexico that had been collected as part of a 2011 survey for the oil industry. A fraction of these samples contained migrated gaseous hydrocarbons, the chief components of oil and gas. These petroleum seeps on the ocean floor harbored distinct microbial communities featuring bacteria and archaea that are well-known inhabitants of deep biosphere sediments.

"Whereas sedimentation slowly buries microbial communities into the deep biosphere, these results show that it's more of a two-way street. The microbes coming back up offer a window to life buried deeper below," Hubert says. "These relatively accessible surface sediments give us a glimpse into the vast, subsurface realm."

The study also adds a new dimension to understanding the metabolic diversity of seabed petroleum seep microbial communities. "If it weren't for the microbes living at hydrocarbon seeps, the oceans would be full of gas and oil," Chakraborty says.

Co-authors Bernie Bernard and James Brooks of TDI-Brooks International obtained the 172 Gulf of Mexico sediment cores and performed geochemical testing on them, setting the stage for microbiology testing at the University of Calgary.

"One of the strengths of this study is the large number of samples analyzed, allowing robust statistical inferences of the microbes present in the petroleum seeps," Ruff says.

Because the seafloor is so difficult to access, explorations of deep-sea ecosystems are often limited by the number and quality of samples. The team used metagenomic approaches to determine what microbes were present in the sediment samples, and genome sequencing of particularly interesting organisms to indicate what their activity in the subsurface might be.

Research paper

Related Links
Marine Biological Laboratory
Water News - Science, Technology and Politics

Tweet

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Simulated deep-sea mining affects ecosystem functions at the seafloor
Bremen, Germany (SPX) Apr 30, 2020
Polymetallic nodules and crusts cover many thousands of square kilometres of the world's deep-sea floor. They contain mainly manganese and iron, but also the valuable metals nickel, cobalt and copper as well as some of the high-tech metals of the rare earths. Since these resources could become scarce on land in the future - for example, due to future needs for batteries, electromobility and digital technologies - marine deposits are economically very interesting. To date, there is no market-ready ... read more