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WHOI Waypoints: Going Deep for an Education

On her 22nd birthday, Diane Poehls received an unusual present: a chance to spend the next day under 2,500 meters of seawater.

On January 18, 2002, the MIT/WHOI Joint Program student made her first dive in Deep Submergence Vehicle Alvin, joining WHOI Assistant Scientist Tim Shank and Pilot Pat Hickey on a voyage to the famed hydrothermal vents at 9º North on the East Pacific Rise. She saw black smokers, shrimp, mussels, and clusters of Riftia tubeworms. With that dive, Poehls realized a childhood dream.

She was researching a 7th grade science project when she found a National Geographic article about a seafloor eruption at 9º N. “I saw the photos of this strange world miles below the surface of the ocean,” Poehls said. “I was intrigued by how it looked like a barren desert in places, and yet there were pockets of absolutely fascinating animals.”

She took a marine biology class in high school, studied aquatic biology in college, and enrolled in the MIT/WHOI graduate program. At age 24, Poehls has already made two Alvin dives and spent 135 days at sea on five oceanographic expeditions.

She plans several more visits to 9ºN, as her thesis research focuses on the creatures who make their homes there. Poehls wants to understand how species migrate from one vent site to the next, a process that has implications for the survival of species.

“Vent environments are ephemeral,” she noted. The black smoker that is spewing today might be dormant in a month or a year. “These animals must somehow get from one patch to the next, sometimes traveling many miles between vents.”

“As soon as vents were discovered, biologists recognized that the dispersal of larvae was an essential yet unknown component of the communities,” said Lauren Mullineaux, a senior scientist in the Biology Department and advisor to Poehls. “Population geneticists assume that larvae arrive at new vents from a large, well-mixed gene pool. Diane knows that dispersal doesn’t work this way in shallow or coastal systems, and it probably doesn’t work this way in vents.”

One of the most controversial questions in modern biology is how populations are connected. “These grandiose communities persist despite constant environmental change and extinction,” Poehls said. “If you accept that fragmentation is a risk to the survival of a species, then vent organisms should be extinct or should never have existed. How do they do it?”

Answering that question is going to require a lot of long hours in the laboratory and a few more trips to the ocean floor. Poehls won’t mind.

“Going to the sea floor is like taking a trip to another world without leaving Earth,” she said. “It sure beats the pictures that we’ve recently seen from Mars, and it doesn’t cost billions of dollars to go there.”

Originally published: July 1, 2004