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Exploring New England’s Recently Discovered Methane Seeps

Setting off from Woods Hole, Massachusetts, on a deep sea expedition to newly discovered methane seeps. (Photo by Jeffrey Marlow)
Setting off from Woods Hole, Massachusetts, on a deep sea expedition to newly discovered methane seeps. (Photo by Jeffrey Marlow)

There’s something about the hallways of the research vessel Atlantis. It’s a unique smell of processed air that compresses time and unleashes a barrage of memories—of sloshing buckets filled with samples, of meetings previewing ambitious dive plans, of nausea, long days, and sleepless nights.

Walking through the blue-floored passageways with boxes of lab equipment, I mentally prepare for the intense days to come—a series of all-nighters befitting the value of the deep-sea samples we’re after. This is my fourth research expedition aboard the Atlantis, but past experience is only going to take me so far; we’re doing things a bit differently this time around.

AT-36 is an ambitious expedition, even by the carpe-diem, plan-each-dive-as-if-it’s-your-last standards of seagoing science. I’m joined by 23 other early-career scientists representing a wide disciplinary diversity not typical of most cruises. We’re here to learn the ropes of the National Deep Submergence Facility, to understand the scientific capabilities of Alvin (a three-person human-occupied submersible) and Sentry (a pre-programmable autonomous underwater vehicle) and, ultimately, to write compelling research proposals incorporating these world-class assets.

“You are the future of deep-sea science,” our all-star cast of mentors reminds us, a sentiment that doesn’t exactly dull the pressure of the tens-of-thousands-of-dollars-per-day voyage.

The science plan is to investigate a series of submarine canyons and newly discovered methane seeps about 150 miles (240 km) from our Woods Hole, Massachusetts, port. With sub-teams coalescing around deep-sea animals, water column-based processes, seafloor sediment microbial activity, and mapping, we’ve developed an ambitious sampling agenda. It all sounds reasonable enough right now, fueled as we are with eight hours of sleep and eight ounces of Pie in the Sky coffee, but experience has taught me to be wary of this optimism. Once out to sea, all bets are off.

The Autonomous Underwater Vehicle Sentry on the deck of the Atlantis. (Photo by Jeffrey Marlow)
The Autonomous Underwater Vehicle Sentry on the deck of the Atlantis. (Photo by Jeffrey Marlow)

Oh yeah, we’re also experimenting with telepresence aboard the Atlantis for the first time.

Such technology—the live streaming of data and video from ship to shore enabled by amplified bandwidth—has been integrated into exploratory operations on a handful of vessels, but using it for research aims is a new challenge, especially when Alvin is involved. Ideally, enhanced communication with a shore-side team will leverage distributed skill sets and ease the time burden of ship-based scientists. (Our group will be split between the Atlantis and the University of Rhode Island’s Inner Space Center—a mission control for the sea—with a planned swap halfway through the expedition.)

It’s a lot to take in, and as we set off through intermittent walls of fog, we begin to get our bearings. Twelve hours away and a kilometer and a half down, a surprising complex of methane seeps—remarkable for their very existence—awaits Alvin’s headlights. Adam Skarke, a Professor of Geology at Mississippi State University, was part of the team that first discovered the seeps; along with Stanford University Professor Anne Dekas, Skarke is serving as co-chief scientist on AT-36. “Widespread methane emission along the U.S. Atlantic margin was not expected,” Skarke explains, “and it raises important questions about the processes driving gas release.”

Methane seeps are generally found at tectonically active margins (like the West Coast of the U.S., where one plate is subducting beneath another) and at sites with well-established pools of degrading organic goo (like the Gulf of Mexico, where vast oil and gas reservoirs are well-known). Oceanographers had believed that the seafloor along the U.S. Atlantic coast was relatively stable, with consistent, cold water temperatures, “suggesting that methane gas there should remain locked in ice-like gas hydrate beneath the seafloor,” according to Skarke.

Actively bubbling seeps and vibrant seafloor oases have thrown these previous assumptions out the window, but new questions have emerged. How did seep ecosystems come to exist in this geologically unusual setting? If plumes of methane—a particularly strong greenhouse gas—can persist where we didn’t think they could, then might they be elsewhere?

These are disquieting questions, as they expose a fundamental uncertainty about the world that is equal parts exciting and alarming. But with a foothold of knowledge from past expeditions and a remarkable set of tools at our disposal, answers, hopefully, are close at hand.