I’ve had some disappointing baths in my time, but never a hot tub of despair. Long may that last, because the ‘Hot Tub of Despair’ isn’t just real - it also embalms any creature that falls in.
Researchers discovered the existential water feature in 2015, while guiding the remotely operated vehicle (ROV) Hercules along the floor of the Gulf of Mexico. Around a day’s boat ride from New Orleans, and a kilometre beneath the surface, scientists from the Ocean Exploration Trust spotted a large, bowl-shaped pool.
Its outer walls, which rise around four metres from the seabed, were encrusted with yellow mussels. Inside, however, lay a grisly collection of bodies: chunky dead crabs and pickled, shrimp-like crustaceans.
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The hapless creatures crawled in but never crawled out, because the Hot Tub (or ‘Jacuzzi’) of Despair is full of dense, toxic brine. The structure sits on top of a cold seep, where methane and other hydrocarbons escape from the seafloor into the surrounding water. As fluid from the seep passes through ancient underground salt deposits, it dissolves the salt, creating a layer of brine so dense that it forms a distinct pool on the seabed.
The brine is balmy – a surprisingly warm 19 degrees Celsius – but lethal. Depleted of oxygen and laced with toxic hydrogen sulphide and methane, the mixture quickly kills most sea creatures that encounter it. As the brine slowly pickles them, their bodies become encrusted with jewels of halite (rock salt) crystals.
Researchers have known about deep-sea brine pools for decades. The first were discovered in the 1960s by scientists aboard the RRS Discovery in the Red Sea. In 2014, researchers piloted a human-occupied vehicle (HOV) called Alvin to another brine pool in the Gulf of Mexico, where the brine was so dense they could ‘land’ their 20-ton submersible on top of it.
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Yet these pools aren’t entirely lifeless.
Extremophile microbes survive in the salty soup, obtaining energy from its chemical compounds. Beyond the brine, the hot tub’s rim and outer walls support a community of specialised animals. The mussels, which help reinforce the walls, have a symbiotic relationship with bacteria living on their gills. These bacteria use dissolved gases to produce nutrients for their hosts. Meanwhile, tube worms pull off a similar feat, relying on bacteria living inside their bodies to turn chemicals from the seep into nutrients.
top image: Ocean floor. Credit: Mitchell pettigrew/ Getty Images
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