Ocean oxygen could hold key to life on other planets

Discovery is creating a buzz in the scientific community, with Professor Andrew Sweetman at the centre.

The groundbreaking discovery of what has been termed ‘Dark Oxygen’ was made in the Pacific Ocean last year by a research team led by Professor Sweetman of the Scottish Association for Marine Science (SAMS).

“We’ve only so far found it at depths of 4,000 metres to 5,000 metres and it appears to be linked to the seafloor,” Professor Sweetman explains. “Those discoveries were in underground caves, in oxygen-minimum zones and at the abyssal Pacific seafloor.”

A three-year research project is to be launched later this year involving purpose-built probes with specialist instrumentation being sent to the deepest parts of the ocean. 

“Initially we will go back to the abyssal Pacific and see if we can detect it again,” he continues. “Then, we will start to think about other areas where oxygen anomalies have been seen previously such as the Solomon Sea. 

“The systems we will build will take all the sensing capabilities to the seafloor. What is special about them is that they will be able to reach the deepest ocean depths – around 11,000 metres.” 

The landers, which are being built to withstand pressures of over one tonne per square centimetre, will also be the first United Kingdom assets deployed with capability of sampling below 6,000 metres of depth. 

Billed as the “most detailed examination of the deep ocean yet”, the research project is considered to have strong potential of revealing clues to the origin of life and sustaining it in space.

Life despite lack of sunlight

“Our discovery of Dark Oxygen was a paradigm shift in our understanding of the deep sea and potentially life on Earth, but it threw up more questions than answers,” states Professor Sweetman. “This new research will enable us to probe some of these scientific questions. If we show that oxygen production is possible in the absence of photosynthesis, it changes the way we look at the possibility of life on other planets too. 

“Indeed, we are already in conversation with experts at NASA who believe Dark Oxygen could reshape our understanding of how life might be sustained on other planets without direct sunlight. 

“If the process that leads to it happening on Earth is found on other planets, then it could contribute oxygen to ocean worlds, such as Europa (one of Jupiter’s moons).”

The project will also be the first to investigate whether hydrogen is released during the creation of Dark Oxygen, if it is used as an energy source for an unusually-large community of microbes in parts of the deep ocean, and how climate change might impact biological activity in the deep sea.

The project has been made possible by a £2m funding package from The Nippon Foundation and will involve collaborators at Boston University and Northwestern University and their teams.

The Nippon Foundation Chair Yohei Sasakawa commented: “The sea is vital to sustaining human life and biodiversity, but even today so much of the deep sea is unknown. We are passionate about innovating to achieve a better society, and we are proud to support Professor Sweetman’s research into Dark Oxygen in the hope that we might learn more about the deep sea and the life which exists at the bottom of the ocean.” 

Sweetman says the research team hopes to start presenting on its findings by mid 2026.

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Newsletter/top image: Professor Andrew Sweetman holding sample; credit: The Nippon Foundation. 

Main image: graphic of air bubbles in the deep ocean; credit: Shutterstock.