There’s a ‘lost city’ deep under the ocean, and it’s unlike anything we’ve seen before: ScienceAlert

There's a 'lost city' deep under the ocean, and it's unlike anything we've seen before: ScienceAlert
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Near the top of a seamount west of the Mid-Atlantic Ridge, a jagged landscape of towers rises from the gloom.

Its creamy carbonate walls and columns appear a ghostly blue in the light of a remote-controlled vehicle sent to explore.

They vary in height from small piles the size of poisonous mushrooms on a large monolith with a height of 60 meters (almost 200 feet). This is the Lost City.

View of the Lost City
A remote-controlled vehicle illuminates the spiers of the Lost City. (D. Kelley/UW/URI-IAO/NOAA).

Discovered by scientists in 2000, more than 700 meters (2,300 feet) below the surface, The Ciudad Perdida hydrothermal field is the longest known vent environment in the ocean. Nothing like it has ever been found.

For at least 120,000 years and perhaps longer, the mantle rising in this part of the world has reacted with seawater to spew hydrogen, methane and other dissolved gases into the ocean.

In the cracks and crevices of field vents, hydrocarbons feed new microbial communities even without the presence of oxygen.

Bacteria in calcite column.
Strands of bacteria living in a calcite vent in the Lost City. (University of Washington/DC BY 3.0).

Chimneys spewing gases as hot as 40°C (104°F) they are home to a large number of snails and crustaceans. Larger animals such as crabs, shrimp, sea urchins, and eels are rare, but still present.

Despite the extreme nature of the environment, it appears to be teeming with life, and researchers believe it deserves our attention and protection.

While other hydrothermal fields like this likely exist elsewhere in the world’s oceans, this is the only one that remotely operated vehicles have been able to find so far.

The hydrocarbons produced by the Lost City vents did not form from atmospheric carbon dioxide or sunlight, but by chemical reactions on the deep seafloor.

Because hydrocarbons are the building blocks of life, this leaves open the possibility that life originated in a habitat like this. And not just on our own planet.

“This is an example of a type of ecosystem that could be active on Enceladus or Europa at this very second,” said microbiologist William Brazelton. saying the smithsonian in 2018, referring to the moons of Saturn and Jupiter.

“And maybe Mars in the past.”

Unlike submarine volcanic vents called black smokerswhich have also been named as a possible first habitat, the ecosystem of the Lost City does not depend on the heat of the magma.

The black smokers produce mainly iron- and sulfur-rich ores, while the chimneys in the Lost City produce up to 100 times more hydrogen and methane.

The Lost City calcite vents are also much, much larger than the black smokers, suggesting they have been active longer.

Lost City High Vent
Nine meter high chimney in the Lost City. (University of Washington/Woods Hole Oceanographic Institution).

The tallest of the monoliths is called Poseidon, after the Greek god of the sea, and it stretches over 60 meters high.

Just northeast of the tower, meanwhile, is a cliff with brief bursts of activity. Researchers at the University of Washington describe the vents here like ‘weep’ with fluid to produce “clumps of delicate, multi-tipped carbonate growths that extend outward like fingers upwards.”

Unfortunately, scientists aren’t the only ones drawn to that unusual terrain.

In 2018, it was announced that Poland had will not be the rights to mine the depths of the sea around The Lost City. While there are no valuable resources to dredge in the thermal field itself, the destruction of the city’s surroundings could have unintended consequences.

Any plume or discharge, triggered by mining, could easily inundate the remarkable habitat, scientists warn.

Therefore, some experts are calling for the Lost City be listed as a World Heritage Site, to protect the natural wonder before it is too late.

For tens of thousands of years, the Lost City has been a testament to the enduring force of life.

It would be like we screwed it up.

A previous version of this article was published in August 2022.

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