You will die if you swam into these ocean pools

The discovery of super salty brine pools on the seabed of the Gulf of Aqaba off the coast of Saudi Arabia could provide insights into the earliest life on Earth, and potential risks to present-day humans inhabiting nearby coastline.

These are among the conclusions of research published in Nature Communications by a team from the University of Miami.

It’s discovered a 10,000 square-metre brine pool and three adjacent ‘mini pools’ (of less than 10 square metres) almost two kilometres beneath the Gulf of Aqaba, off the coast of Saudi Arabia.

Until now, brine pools – which form when dissolved salts accumulate within seafloor cavities – have only been found in the Red Sea, Mediterranean Sea and Gulf of Mexico. 

And unlike those in the nearby Red Sea, the Aqaba pools are located within just a few kilometres of the closest shoreline. 

Life finds a way in one of the world’s harshest environments

Oxygen is generally necessary to sustain life whether on land or within water. 

So it’s no surprise deep-sea brine pools are not suitable for most of the ocean’s animals.

But they’re not devoid of life – they’re brimming with it.

Communities of microbes – dubbed ‘extremophiles’ for their ability to withstand conditions inhospitable to most lifeforms – comfortably exist within harsh, hypersaline environments. 

These simple organisms use an exotic process called chemosynthesis to obtain their energy from the available molecules surrounding them. 

But they’re not without neighbours – beyond the briny boundary are an assortment of fish, crustaceans and molluscs.  

Of these more complex lifeforms, those that venture into these pools are usually stunned or killed, giving the others carrion to scavenge as it drifts into their more oxygenated waters. 

It’s an unusual ecosystem in one of the most unlikely of places on the planet, discovered in the final moments of a remotely operated underwater vehicle (ROV) petrol operated by the University of Miami team. 

ROVs are special vehicles launched from high-tech exploration ships like the OceanXplorer used on this study mission. ROVs are specialty-designed craft capable of reaching the world’s most inaccessible, high-pressure depths.

But it was very nearly a discovery missed, with the researchers only coming across the pools in the final moments of their underwater research patrols.

“We were very lucky,” says the University of Miami’s Sam Purkis.

“The discovery came in the last five minutes of the ten-hour ROV dive that we could dedicate to this project.”

Purkis believes these microbial communities will help further understanding of where life can thrive – and survive – on Earth and other worlds.

“Until we understand the limits of life on Earth, it will be difficult to determine if alien planets can host any living beings,” says Purkis.

“Microbes that survive in extreme environments can help trace the limits of life on Earth and can be applied to the search for life elsewhere in our solar system and beyond.”

Brine pools provide ‘exquisite’ record keeping

Upon the discovery of these brine pool complexes, Purkis’ team proceeded to extract core samples of their sedimentary layers.

Beyond the discovery of the microbes that inhabit these pools, the researchers found sedimentary records that provide unique insights into over a millennium of regional rainfall. Earthquake and tsunami history.

The sedimentary deposits likely show flash floods may occur in the Gulf of Aqaba several times each year to once every few decades, while tsunamis resulting from earthquakes occur once a century on average. 

These discoveries are important in the context of nearby urban developments in Saudi Arabia being carried out by the research sponsor NEOM, for whom the pools have now been named.

“Given their high biodiversity, we believe our discovery of the NEOM Brine Pools is prescient – the coastline of the Gulf of Aqaba is rapidly urbanising [and] this bathyal ecosystem should be afforded the same protection as the vibrant shallow-water reefs which situate 1700 metres above the pools,” they say.

The discovery of seismic activity in the pools’ sedimentary record could also be an important consideration for governments given the development of nearby coastal cities, and is set to form the basis of further risk assessment in Aqaba.