Ocean bed oxygen production changes understanding of marine environments

The discovery could fundamentally alter theories about the origins of life on Earth. 

A process associated with polymetallic nodules on the sea floor of the Pacific Ocean is no believed to responsible for oxygen production. It had previously been understood that this process was not possible, and any oxygen found in deep waters had travelled there on currents. 

The revelation is being touted as groundbreaking, fundamentally changing our view of the ocean floor, and emphasising how little is still known about the most remote regions on the planet. As a result of the study, published this week in the journal Nature Geoscience, experts are once again calling for a halt to deep sea mining, which causes widespread damage to the marine environment, vast areas of which remain largely unchartered. 

While conducting experiments in the NORI-D license area of the Clarion-Clipperton Zone, a target area for deep sea mining, scientists found that rather than oxygen in deep waters decreasing over time, in some places they actually tripled in a matter of days. This led to the discovery that polymetallic nodules may be capable of producing enough voltage to split water into hydrogen and oxygen, a process known seawater electrolysis. This appears to be unique to the species.

‘The discovery that a process associated with polymetallic nodules is producing oxygen, in an area targeted by the deep-sea mining industry, provides further support on the urgent need for a moratorium,’ said DSCC Deep-Sea Mining Global Campaign Lead Sofia Tsenikli. ‘This research emphasizes just how much we still have to discover and learn about the deep sea and raises more questions about how deep-sea mining could impact deep-sea life and processes. It is human arrogance to continue to push to mine these nodules that are producing potential life-sustaining oxygen in an extraordinarily important and unique ecosystem.’

Scientists are concerned that smothering or even removing the nodules through deep-sea mining could change seafloor oxygen production. In turn, this could have a significant impact on life at such depths, and processes including carbon cycling. Wider implications could see the development of new theories about the origins of life on Earth, and the potential for this to be repeated on other planets. 

‘The fact that oxygen can be made independently of the surface world has a lot of exciting implications for the distribution of animal life, not only in Earth’s oceans, but also, potentially, beyond our planet,’ said Jeff Marlow, co-author of the paper.

‘Oxygen provides enough energy for big organisms like animals to survive, so a process that makes oxygen without sunlight could allow for larger life forms to inhabit the deep, dark waters of “ocean worlds” like Enceladus or Europa,’ he continued. ‘We’ve typically centered the search for life beyond Earth around microbes using reduced chemicals for energy – that still may be the best approach, but this result shows that it might be wise to expand our perspective.’

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Image: Nichika Yoshida