Going Deep

Joanna Lott
January 01, 2003

At 3:00, seven hours behind schedule, Atlantis's horn sounded and the ship pulled away from the docks, starting her day-and-a-half journey south to the East Pacific Rise. The hillsides of Manzanillo, Mexico, tightly packed with houses painted bright shades of green and yellow, slowly disappeared into the distance—our last look at land for 23 days.

title card with images of underwater yellow tubes and machine
Rod Catanach, Woods Hole Oceanographic Institution and Robert Hessler, Scripps Institution of Oceanography

Left and inset, Submersible Alvin begins another research dive; right, Tube-worms and mussels thrive at a hydrothermal vent.

The scientists, lacking sea legs, were easy to distinguish from the experienced Atlantis crew. Led by Penn State biologist Charles Fisher, they represented Penn State, the University of California at Santa Barbara, and William & Mary. Other researchers came from North Carolina and Alaska, as well as Austria, British Columbia, and the U.K. Altogether 22 scientists had signed on to study the exotic communities of life that thrive at the hot-water geysers, or hydrothermal vents, 2,500 meters below the surface of the ocean. When I had first met Fisher ten days earlier, he had happened to mention that there was one empty bunk on this upcoming cruise. Now here I was—here we all were and, seasick or not, there was work to be done.

Upon boarding, the scientists had converged on Atlantis's five labs and quickly set up shop, claiming work space and unloading their gear. They had just over a day to build most of what they would need—devices you can't order from any catalogue. Some tools they had brought with them, including Fisher's Bush Master and Chimney Master—two large nets designed specifically for scooping up vent animals. But the rest they would build aboard ship. Half the team worked on retrieval containers for the collections of creatures they would pick up from the sea floor. These containers—milk crates, PVC boxes, and altered pickle buckets—would be attached to Alvin's science basket, a platform mounted on the front of the submersible the night before each dive. Stephan Hourdez, a Penn State post-doc, put together the bioboxes that would seal in the creatures they wanted brought up alive. Penn State graduate student Breea Govenar worked in the ship's machine shop cutting PVC pipe to build the physical housing that would encase the water sampler and thermistor arrays—delicate tools that measure water temperature and chemistry.

The afternoon was spent drilling, hammering, hot gluing, sawing, sewing, and all around jerry-rigging. At day's end, those who could eat enjoyed a hearty dinner in the mess hall, then gathered on the stern to watch our first of many sunsets at sea. Land had long since disappeared, and now there were just water and sky—blue on blue. Pinks and yellows began to paint the horizon, blue turned to slate gray, and night settled in. The line where ocean meets sky vanished, and the 3,200-ton ship felt airborne as the stars swayed back and forth in the great black sea of night.

underwater maroon vents
Jim Welch, Wittenberg University

Biological community at a hydrothermal vent

Nine degrees north of the equator, 500 miles off the Mexican coast, a mile and a half below the surface of the Pacific Ocean, the world's longest volcanic mountain chain rises from the ocean floor. Too deep to be reached by sunlight, life is scarce on much of the surface of this mountain. But here at the East Pacific Rise, life is teeming. Here, exotic creatures thrive where hot water and chemicals spew from beneath the Earth's crust.

These strange animals were first discovered in 1977 by geologists drawn to another section of the mid-ocean ridge system, the Galapagos Rift, by the discovery of hot water welling up through the ocean floor. A closer inspection revealed communities of animals living on and around these hot water vents.

In 1979 Alvin, a Navy-owned sub designed to recover lost submarines and now used mostly for science, made her first dive at the East Pacific Rise only to discover the same thing: strange new species of animals thriving where plumes of hot water—as hot as 350 degrees C—rose from beneath the sea floor. Since then, scientists have returned again and again to this spot at 9 50'N on the East Pacific Rise where hydrothermal vents and biological communities are plentiful and potential for the discovery of new vent sites is high.

A hydrothermal vent is created when magma from deep in the Earth pushes its way to the surface between two tectonic plates, causing cracks to form in the sea floor. Cold ocean water—about 2 degrees C—seeps down through the cracks and is heated by the magma. This water, now extremely hot and rich in hydrogen sulfide picked up in underground chemical reactions, rises and bursts through the ocean floor.

brown fish swimming in sea
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Vent fish emerging from high-temperature vent region known as "Hole-to-Hell."

One morning in the ship's computer lab, Fisher leaned back in his chair across the table while I, bleary-eyed, tried to make sense of what I was learning. Arms crossed, head cocked to the right, his youthful face pink from the sun, Fisher squinted at me as if the answers to my questions were just beyond his line of sight. He ran through the basics of vent biology like he was singing his ABCs.

From what we know about life, he told me, no animal should survive so far from sunlight, where oxygen levels are low and sulfide levels high. And yet they do survive. These communities include some familiar-looking animals, such as mussels and clams, but also tubeworms, giant worms encased in thick protective tubes, which bear little resemblance to any previously discovered creature.

“Life at these vent sites is not based on sunlight, like everything on the surface of the planet. It's based on the energy of the center of the Earth,” Fisher explained. Tubeworms and other animals found at the vents rely on highly specialized bacteria—chemoautotrophs—that turn hydrogen sulfide into food. He compared the process to photosynthesis: “Green plants have little organelles called chloroplasts where all the food is made. Well, vent animals have little symbionts—the bacteria—that function like the chloroplast does in a plant.”

On this cruise, he continued, the object was to gain a clearer picture of the vent habitat as a whole. “We want to see who all the players are, how many of them there are, and how much biomass—living matter—there is. Our goal is to actually say, ‘OK, here's what all the little pieces do,' then to pull all that together and tell you how the whole vent works. When we're done, we should be able to make models and calculate how much productivity there is.”

tentacles of a fish
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Sea anemone

These calculations are a crucial part of Govenar's Ph.D. work. She is particularly interested in the distribution of species at the vents. “I am essentially a community ecologist. I want to know where the animals are and why,” she said.

On this, her first cruise, Govenar would make three dives in Alvin, each time bringing back area samples—intact chunks of vent communities. Her first dive would be with Fisher and Alvin pilot and expedition leader Patrick Hickey.

The entire science party gathered to watch that first launch. I climbed to a landing a level above the fantail, the fan-shaped rear deck, and leaned out over the railing for a better view. Below me, Govenar, ready early, stood chatting nervously with her fellow graduate students and occasionally glancing over her shoulder as the Alvin Operations team made final preparations. Gavin Eppard, a young pilot-in-training, shirtless, cigarette hanging from his mouth, the hammerhead shark tattoo on his right shoulder glistening with sweat in the dewy morning heat, worked along-side Brian Leach, a newer pilot-in-training, who seemed to want to emulate Eppard's ease around the sub. They worked Alvin over from top to bottom, while the three seasoned pilots—older, more experienced, but no less excited about their job—checked all the systems.

Just before 8:00, Alvin was rolled out of her hangar and fastened to a noose of Kevlar rope hanging from the A-Frame—the hydraulic system that swings the sub out over the deck and plunks her down in the sea. At 8:00, after a final test of launch systems, Alvin was ready to go. Govenar laughed and followed Fisher and Hickey up the A-Frame stairs, turned and waved, then climbed into the tiny belly of the sub. At 8:11, the A-Frame lowered Alvin into the water, and the sub began its two-hour descent to the ocean floor.

white lobster
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Squat lobster

“It is an amazing feeling to see the actual bottom of the ocean,” Govenar said after the dive. “But then it is even more exhilarating to see the animals. You see nothing at all, then you get closer to a vent and you see a few worms, then a few crabs, and then, it's like the curtain went up and . . . you're just there. I was the first of the three of us to spot the tubeworms,” she continued. “Big white tubes with bright fleshy plumes. I couldn't even stammer out what I was observing . ‘Uh, there are . . . there are . . . Oh my gosh! There are tubeworms!' With the lights on outside the sub you feel like you could just get out and walk around.”

One of the goals of the first dive, Fisher said, was to revisit as many known sites as possible. In the two years since any of the scientists on board had visited them, these sites might have changed drastically, he explained. “These systems are largely geologically driven—the fauna is very sensitive to changes in the chemistry of the water bathing it, and, of course, to the not-infrequent volcanic eruptions.” So Hickey took Fisher and Govenar on a sightseeing tour.

A video taken by the sub's cameras showed what they saw: Like fields of flowers, patches of tubeworms—white tubes with blossoms like red calla lilies—sway in the shimmering water. Tiny limpets, like aphids, cover the outsides of the tubes. A crab scurries past, and one after another, the plumes disappear, drawn back into their protective tubes.

Even expecting to see dramatic changes, all I can say is, Wow! Fisher wrote after the first dive. The first site we visited, Tica, used to be populated by a few small Riftia [tubeworms] and now hosts one of the largest and most impressive stands of tubeworms I've ever seen: thousands and thousands of individuals in a clump 4 to 5 meters in diameter and at least that high. Another site we visited, Riftia Fields, was so named because of the many clumps of thriving tubeworms there. Now, only a few sickly looking clumps remain among many dead and empty tubes. But the area has been settled by hundreds of anemones and invaded by numerous galatheid crabs and large vent fish. Two of our other study sites, East Wall and Biovent, used to be populated by a fairly even mix of mussels and freestanding tubeworm clumps. Now mussels cover the landscape, with the occasional tubeworm plume sticking out of the top of a mound of mussels.

machine next to underwater cloud
Dan Fornari, Woods Hole Oceanographic Institution

Alvin manipulator arm picks up a temperature probe near black smoker

Using Bush Master, Fisher's custom-made collection device (“It's like a huge webbed hand that can pick everything up,” Govenar said), they grabbed samples, mostly tubeworms and mussels, for shipboard analysis. They also deployed two arrays of thermistors that would keep track of water temperatures at communities they had chosen for study over the next few weeks.

Back on Atlantis, members of the Penn State team readied themselves for recovery and also to set up a surprise for Govenar—the traditional first-dive initiation. The crowd cheered when she popped her head up out of the hatch. She climbed wearily from the sub and down the A-Frame stairs, smiling triumphantly but looking a little green around the gills, and approached her colleagues, arms outstretched for a hug. Instead, working in teams of two, they doused her with three buckets of ice-cold water. Still a little seasick, Govenar, water dripping from her nose and hair, posed for a few pictures before heading inside to shower and change, then hurrying back on deck to help with the samples.

Days aboard Atlantis started long before the sky made its slow transition from dark to light. By 4:00 a.m., Penn State graduate student Susan Carney would be up preparing the water sampler for the day's dive. This device, made up of four syringes connected to a tiny wand at the end of a fine line of tubing, can collect water with pinpoint precision: up against a tubeworm plume, right next to a mussel or clam, or even in crevices in the rock. In order to make sure the samples are pure, the syringes had to be degassed and primed before each use, a process that took Carney, assisted by Penn State undergraduate Therese Waltz, about three hours.

At 6:00 the Alvin pilots started their two-hour pre-launch preparations, and the rest of the Penn State team joined Carney and Waltz for a final check of the equipment loaded into Alvin's science basket. The scientists had until 7:00 to finish any last-minute adjustments. After that, the pilots would shoo them away to perform their “walk around”—the pre-launch inspection involving a 17-page checklist that covered everything from the A-Frame to the Avon, the small boat used to help safe-guard the launch.

maroon tubeworms and crusty clams
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Tubeworms and clams with a swarm of small crustaceans

For this, the cruise's fifth launch, lightning flashed in the dark morning sky, hinting at the hot and sticky day ahead as the science party gathered to watch. As usual, by 8:00 sharp a crowd had formed, sitting in the few plastic chairs on deck or leaning over the rail one or two decks up, waiting for the show to begin.

It was another dive day for Fisher, this time a “PIT” (pilot-in-training) dive. Trainee Gavin Eppard would be working with the veteran BLee Williams.

As the sun attempted to burn through the soupy blue haze, scientists and crew squinted to watch the divers climb into the sub. Two swimmers took their places on top of Alvin, securing her to the A-Frame. The Avon was lowered into the sea by a large crane on the starboard side. Once Alvin was in the water, the swimmers detached the main lift line and the tail line, then dove to inspect the valves and emergency lights. One swimmer then climbed back on Alvin and used a portable sound-powered telephone housed in the sail to tell the pilot below that the sub was ready to dive. The Avon then picked up the swimmers and waited for Alvin to submerge.

Before the sub had fully disappeared under the water, pilot Williams was on the radio. There was a problem. Word traveled quickly around the ship that something was wrong.

An hour after she had hit the water, the sub was finally hoisted back onto the ship. One of the motor controllers for the hydraulic system had blown. And since the back-up controller had failed the day before, Fisher and Williams had decided to bring the sub in.

By 11:00, the Alvin pilots had repaired the system. At 11:30 they re-launched.

pink fish face by yellow tubes
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Zoarcid fish with crab and tubeworms

“Bringing it back up is not a very common occurrence,” pilot Phillip Forte said an hour later. We were sitting in the quiet of top lab, the Alvin operations-control room just aft of the bridge, monitoring Alvin's progress. A screen behind Forte showed Alvin's coordinates in lime green lights. Transponders blipped in the background. “That sub is pretty damn reliable,” Forte said.

Meanwhile on the fantail the Penn State team got ready for the afternoon recovery—the busiest time of the day. As soon as the sub touched the deck, an advance team of scientists in life preservers rushed it like ER doctors on a Saturday night, “life-flighting” the live animals from Alvin's basket to coolers of ice-cold seawater. Meanwhile the off-day pilots wheeled the sub back into its hangar so the real operation could begin. There the full swarm of scientists set upon the sub, picking it clean of remaining samples while the Alvin team prepped it for the next dive.

Hours of planning precede each dive and recovery. In fact, Govenar, as chief graduate student on the cruise, had accounted for every possible dive scenario even before leaving University Park, and packed every conceivable piece of equipment needed.

“You need a hundred different kinds of glue,” she said. “You need silicone sealant, quick drying epoxy, slow drying epoxy, epoxy remover, you need duct tape—like crazy you need duct tape. When that sub comes back you need nets, you need sieves, you need plastic buckets, you need graduated cylinders in many different sizes—all of your dissection tools—you need rope, twine, spoons, little plastic knives, sharp scalpels with different blades, a brush to clean off the balance . . . and everything is intensified because you're trying to do so much, and not to lose a single sample.

red tubeworms with eel-like fish
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Tubeworms with Zoarcid fish

“Then you need to prepare for preserving your samples. Are you going to keep them alive? Fresh? Frozen? Do you want them frozen to minus 20? To minus 70? In liquid nitrogen? You need a different level of containment for each.”

Seven or eight buckets—some empty, some filled with seawater, others with tap water—had to be stationed, labeled, and ready to go before each recovery. Everyone had a job, from siphoning to sieving to general gofer, and every job was carefully defined to prevent mistakes.

“What if someone dumps the wrong bucket over the side?” I asked. Govenar put her head down and pounded her fists on the table: “Don't scare me like that!” she moaned, only half-joking.

Evenings were for the analytical lab. Sunburned, running on adrenaline (and caffeine), the Penn State team—graduate students Govenar, Susan Carney, and Sharmishtha Dattagupta, post-doc Stephan Hourdez, and undergraduate Therese Waltz—spent hours together in the small room, bent over the plastic-covered table dissecting tubeworms, or sifting through shallow pans holding the last of the day's seawater, tweezing limpets, snails, tiny fuzzy-looking worms, and other barely visible creatures, accounting for every animal that had come up. On desks at either end of the room, laptops and CD players whirred, and weary young biologists entered data to the beat of techno music.

Riftia pachyptila (the giant tubeworm) is a distant relative of the common earthworm, but much, much bigger—up to a meter long, Govenar explained as she set me up with a razor blade, a tape measure, and a “not quite dead” tubeworm. But it doesn't move around freely like an earthworm, she continued. It attaches itself to the basalt rock near a vent, grows a thick white tube of chitin, the same material as a shrimp's shell, and stays put. The worm's plume, the flower-like part that sticks out from the tube, picks up hydrogen sulfide from the hot vent water and oxygen from the cooler seawater. The symbiotic bacteria living in the worm's trophosome, a large organ in the center of its body, convert these chemicals into energy.

worms with white tentacles
Richard Lutz, Rutgers University,Stephen Low Productions,and Woods Hole Oceanographic Institution

Serpulid worms

The first job was to carefully measure the length and diameter of the tube and the length of the worm inside. Next, see how these attributes correlate to the weight. “And we see what kinds of relationships fall out,” said Govenar. “Ultimately all that descriptive data gets us in a position where we can ask better questions, and form more specific hypotheses.”

I steadied myself against the motion of the ship and worked my razor blade slowly down the tube of a worm the length of my forearm, managing to cleanly remove it without drawing blood. I held the soft, vulnerable worm in my hands and was about to lay it out on the table to measure it, when it flinched. I threw it across the table. “They still startle me sometimes too,” Govenar said, flashing a patient smile.

“Ooh, I've got a bleeder here,” said Dattagupta, as she sliced through a tube, nicking the flesh of the soft worm inside. Blood dripped and then poured from the worm into the beaker she quickly grabbed to collect it. The water in the beaker turned deep red. Red, like human blood. That's because these vent creatures all have hemoglobin, the same respiratory pigment that colors human blood, Hourdez explained.

In fact, “These animals' hemoglobin has a high affinity for oxygen—they bind it very easily,” he said. This is especially important to their survival. “Animals at vents need as much oxygen as any other animal, so they have to have special adaptations to extract it from this oxygen-poor environment.”

Hourdez has studied hemoglobin in the scaleworm—a fuzzy hot-vent version of a caterpillar. “When I started my research,” he said, “I expected to find something fairly straightforward. It was not. It was a new type of structure.” Unlike human hemoglobin, for example, the scaleworm version can work outside the cell.

Someday, Hourdez predicted, this extra-cellular function might be the basis for advances in blood transfusion technology. “You could have dried-up hemoglobin, and when you need it, you add water, shake it, and it's ready to be used.”

Another surprise about tubeworms, Fisher told me the next morning over coffee in the galley, is that they don't appear to be at the base of the vent-community food chain.

“All the little limpets and snails, those guys are mostly grazers or filter feeders. They're mowing down the bacteria. Fish and crabs are eating the limpets and snails and the shrimp, so you have your regular little food chain. It's just that the tubeworms aren't the basis of it. Which is strange, because there's all this biomass there and almost nothing's eating it.”

“Everybody thought that the really wild thing about tubeworms was that the environment was harsh,” Fisher went on, “but really, once you get more and more into it, what's amazing is how spatially and temporally variable they are. A tubeworm might experience a 20- or 30-degree temperature gradient over the length of its body. How do you get your blood to work right in that kind of environment?

“They may wake up and they're bathed in 2 degrees C water, and ten minutes later it's 30 degrees C water, and ten minutes later it's back to 2 degrees C. They may stay in 2 degrees for a couple of days, and go 30 degrees for a couple of days.

“It's unpredictable and dynamic, and that's a tough thing to adapt to. Animals adapt. That's what life's about. That's evolution. But to adapt to an environment that's so dynamic . . . that's wild.”

Charles Fisher, Ph.D., is professor of biology and assistant department head for graduate education in the Eberly College of Science, 219 Mueller Lab, University Park, PA 16802; 814-865-3365; cfisher@psu.edu. Breea Govenar, Sharmishtha Dattagupta, and Susan Carney are Ph.D. students in biology. Stephan Hourdez is a post-doctoral fellow in biology. Therese Waltz is a junior majoring in biology. Her participation in the cruise was funded by the Eberly College of Science; the cruise itself was funded through several grants from the National Science Foundation as part of the RIDGE (Ridge Interdisciplinary Global Experiments) program. For dispatches from the cruise see www.rps.psu.edu/deep/.

Last Updated January 01, 2003