Singing Vents

Long assumed to be silent, fluids in black smoker hydrothermal vents not only generate rumbling sounds but, as an added surprise, they produce resonant tones.

Scientists have wondered if the sound and vibrations of black smokers are the reason fish in total darkness avoid being poached by waters as hot as 750 F.  Similar sounds could also guide fish to the smorgasbord of tube worms, mussels, shrimp, snails and other fauna at vents with more temperate waters.

Hydrothermal vents, discovered in the 1970s, are found along volcanically active ridges where seawater seeps into the seafloor, picks up heat and minerals and then vents back into the ocean depths. The hottest and most vigorous of the vents are black smokers, so called because when the fluids they emit hit the icy cold seawater, minerals in the fluids precipitate out and it looks just like dark, billowing smoke.

Because of a paper published 15 years ago, it had been thought the vents were probably playing only the sounds of silence. Still a number of scientists suspected that the vents could be generating sounds, given the obvious turbulence of the flows.

It was decided that new recordings should be attempted because researchers are looking for new ways to measure vent flows, which are a source of heat and minerals in the world's oceans that scientists would like to understand better. Commonly used instruments to measure flow are often short lived when inserted in the superheated, corrosive black-smoker fluids.

Researchers submerged a deep-sea digital acoustic recording system in the Main Endeavour vent field. The field is on the seafloor about 300 miles west of Seattle on the Juan de Fuca Ridge. They recorded 45 hours of sound at the vent scientists call "Sully" and 136 hours at the vent called "Puffer."

How loud would it be if you were sitting a foot away? That's something you couldn't actually do because the pressure where most black smokers are found is so intense that you'd implode. The sound level would be somewhere between conversational speech and a hairdryer, scientists say.

---LiveScience Staff

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Credit: University of Washington