Deepest High-Temperature Hydrothermal Vents Discovered In The Pacific

Carbonate chimneys. Credit: MBARI
Josh Davis 03 Jun 2015, 19:55

During a recent expedition to the Gulf of California, researchers uncovered one of its deepest, darkest secrets. They stumbled across the deepest known high-temperature hydrothermal vents in the Pacific Ocean, lying more than 3,800 meters (12,500 feet) down and surrounded by its own unique community of creatures.

The team, working at the Monterey Bay Aquarium Research Institute (MBARI), first realized that they might be onto something when they looked at the sonar data collected by an autonomous underwater vehicle (AUV). The little yellow robot spent a couple of days whizzing along at about 50 meters (164 feet) above the Gulf's floor, mapping its depth and shape.

“Before the AUV survey of Pescadero Basin, all we knew was that this area was really deep and filled with sediment. I was hoping to find a few outcrops of lava on the seafloor,” said David Clague, a geologists at MBARI. “But we got lucky. The vent field was right on the edge of our survey area, along a fault at the western edge of the basin.”

When the team then analyzed the data collected by the AUV, they found mounds and spires rising from the sea bed, and a spike in the temperature in the region. This was prime evidence that there might be some vents hiding in the dark. So they sent a remotely operated vehicle (ROV) down to investigate, and collected videos and samples from the underwater chimneys spewing superheated water into the chilly water of the Gulf.

When the samples made it back to the surface, the scientists were in for even more of a surprise. Rather than being made of dark sulfide minerals as they were expecting, the chimneys from this vent field were made of light-colored carbonate mineral. This makes the Pescadero Basin only the second place in the world where carbonate chimneys have been found. They made three more dives at the site to establish what animal communities lived around the hydrothermal vents.

They discovered that different parts of the vent field, which stretched for 400 meters (1,312 feet), had differing geology, revealing at least three distinct types of hydrothermal chimneys. In addition to the carbonate vents, they also found black smokers and hydrothermal seeps. Each region harbored its own specific animal clique.

What united the three areas, however, was that the dominant clams and tubeworms that lived around the vents, and can grow to over 2 meters (6 feet) in length, host specialized bacteria that allows the worms to feed off the chemicals rich in heavy metals and toxins that spew out of the vents. The team plan on going back to the chimneys to try and figure out what it is that determines what type of vents form where.      

Check out the video of the vents captured by the ROV below:

 

 

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