Dark Oxygen and “Sea Potatoes” – Exploring the Mysteries of the Dark Ocean

The bottom of the ocean is a dark and mysterious region, which is surprisingly little explored, with only 26.1% of the global sea floor having been mapped, as of June 2024 (according to NOAA). With the immense difficulty of being unable to explore these undisturbed spaces, due to dangerously high pressures at the bottom of the ocean, there is still lots that we don’t yet know about the depths beneath our feet.  

You may find yourself wondering how organisms survive in these isolated environments. With no light reaching the extreme depths of the ocean, plankton and algae can’t survive in these regions, as they have no access to sunlight for photosynthesis. As plankton and algae provide the main sources of oxygen in the ocean, this raises considerable questions as to where oxygen is sourced from, for deep-sea creatures. There have been several theories proposed to answer these questions of where this ‘Dark Oxygen’ stems from. 

Recycling Theory 

One of the original theories about how oxygen reaches the dark depths of the ocean, is that it gets slowly cycled through, from the surface. This theory plays on the assumption that oxygen from the ocean’s surface slowly circulates through the ocean, moving around the Earth’s perimeter and gradually sinking down to the deepest depths. Interestingly, it is believed that it can take thousands of years for this circulation to occur. Oxygen at the bottom of the ocean is likely to have originated from a completely different location, which could even have travelled all the way from the other side of the planet! This suggests that the oxygen currently circulating at the bottom of the ocean could have been on an extremely long journey, from the top of the ocean. 

Sea Potatoes 

Recent research has revealed that there are unique polymetallic nodules laying on the ocean floor, nicknamed ‘Sea Potatoes’. These fascinating structures are composed of Manganese, Nickel, Copper and Cobalt, acting as a valuable source of oxygen. The ‘Sea Potatoes’ act by electrolysing water, splitting up water molecules (H20), into Hydrogen (H2) and Oxygen (O) molecules. This also creates a current (electricity). Therefore, a ready supply of ‘dark oxygen’ is provided, taking the place and function of traditional algae and plankton. 

Life on other planets 

There are some exciting ideas from researchers, who have suggested that ‘Sea Potatoes’ may also be present on other planets. This implies that oxygen could be being produced by these underwater batteries, creating oxygen-rich environments on planets and moons, other than earth. Life could therefore potentially thrive on undiscovered planets and moons, raising more interests into looking for extra-terrestrial life. 

Utilising “Sea Potatoes” 

Multiple mining companies have alleged plans, (according to the BBC) to collect these ‘Sea Potatoes’, particularly for extraction of the valuable metals composing them, which can be used in batteries. Whilst these nodules would provide a useful supply of precious metals, environmental considerations need to be addressed. Marine scientist fear that the extraction of ‘Sea Potatoes’ could result in significant damage to marine life that relies upon the oxygen provided by these nodules. According to the BBC, Professor Sweetman described the effect of taking these nodules in a simplified manner, ‘like a battery in a torch’, and that, ‘You put one battery in, it doesn’t light up. You put two in, and you’ve got enough voltage to light up the torch. So, when nodules are sitting at the sea floor, in contact with one another, they’re working in unison – like multiple batteries’. Therefore, if we start to remove the nodules from this fragile deep-sea ecosystem, oxygen supplies could begin to rapidly plummet, causing disastrous effects for organisms. 

 As the nodules take millions of years to form, due to the slow movement of tiny fragments of metals, if we took this valuable ocean resource, we could be imposing a significant threat to deep-sea ecosystems. The BBC has reported that more than 800 marine scientists from 44 countries have signed a petition highlighting the environmental risks and calling for a pause to this devastating mining activity. Clearly, it is vital that going forwards into exploring the utilisation of ‘Sea Potatoes’, we take careful consideration over the devastating ecological impacts that our actions could have. 

Sources: 

Photo – Freepik vectorpouch  

BBC inside science podcast – https://www.bbc.co.uk/programmes/m00274yp 

BBC news article - https://www.bbc.co.uk/news/articles/c728ven2v9eo 

https://oceanexplorer.noaa.gov/facts/explored.html