16,000 Feet Under the Sea: Deepest Hydrothermal Vent Discovered
Want to know what early or extraterrestrial life might look like? You might try looking at Earth’s extremes: the coldest, highest, and deepest places on our planet. One unmanned research vehicle just tried the last of these strategies, and took samples from a hydrothermal vent plume 16,000 feet under the sea–about 2,000 feet deeper than the previous record-holding vent.
A research team led by Woods Hole Oceanographic Institution (WHOI) and including scientists at NASA’s Jet Propulsion Laboratory studied three hydrothermal vents, found along an underwater ridge in the Caribbean called the Mid-Cayman Rise. They published their findings yesterday in The Proceedings of the National Academy of Sciences.
Hydrothermal vents are usually found in spots where the Earth’s tectonic are moving away from each other, creating a weird zone of raw chemistry. A mixture of hot vent fluids and cold deep-ocean water form plumes, which can contain dissolved chemicals, minerals, and microbes. Instead of searching the entire 60-mile-long ridge with the vehicle, the team scouted for chemicals from the plume to zero-in on the vents.
“Every time you get a hydrothermal system, it’s wet and hot, and you get water and rocks interacting. Wherever this happens on the seafloor, life takes advantage,” said geophysicist Chris German of the Woods Hole Oceanographic Institute. “Every time you find seawater interacting with volcanic rock, there’s weird and wonderful life associated with it.” [Wired]
Researchers were surprised to find along the ridge three very different types of vents–each type being characterized by the kind of rock where the vent appears.
Chris German, a WHOI geochemist … has pioneered the use of autonomous underwater vehicles (AUVs) to search for hydrothermal vent sites. “Finding evidence for three sites was quite unexpected–but then finding out that our data indicated that each site represents a different style of venting–one of every kind known, all in pretty much the same place–was extraordinarily cool.” [WHOI]
The researchers have found deep-sea bacteria in water samples from these vents’ plumes, and they hope to one day send vehicles further into the depths–but that will require upgraded vehicles that can maneuver at such extreme depths. NASA researcher and study coauthor Max Coleman thinks such an effort would be worth it, since at least one of the vents may have conditions similar to Europa’s seafloor.
“Most life on Earth is sustained by food chains that begin with sunlight as their energy source. That’s not an option for possible life deep in the ocean of Jupiter’s icy moon Europa, prioritized by NASA for future exploration. However, organisms around the deep vents get energy from the chemicals in hydrothermal fluid, a scenario we think is similar to the seafloor of Europa, and this work will help us understand what we might find when we search for life there.” [NASA]
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