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September 2003

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Deep Science

By Gregory Stone
We were 85 feet underwater and more than five miles off the Florida coast when the lights went out. It was night, and conservationist Craig Taylor and I had been diving for two hours by the dim beams of the Aquarius research station—our underwater home and, at that depth, our only safe haven. About the size of a railroad freight car, Aquarius looked like a spaceship on the seafloor, an interior glow filling her view ports, exterior spotlights illuminating her sides and legs. When she lost power, she simply disappeared into the inky blackness, and I felt as cut off from the world as an astronaut stranded in space.
I fought the impulse to head for the surface, which is what scuba divers are trained to do when they get into trouble, because this was no ordinary dive. For the past four days we'd been living in Aquarius as aquanauts, and by now our bodies were saturated with nitrogen. If I surfaced quickly, without decompression, dissolved nitrogen in my body would expand from the sharp decrease in pressure, forming bubbles that could painfully squeeze nerves, block blood flow, or cause brain damage. Decompression sickness probably would kill me.
Suddenly Aquarius's emergency siren started wailing—a signal for all aquanauts to return immediately. The piercing sound, however, seemed to come from all directions. Breathing heavily on my scuba tanks as I swam through the darkness, I used my emergency lights to search for the web of excursion lines that had been mapped out for us during our one-week training session. These guidelines were a safety measure to help us navigate around the reef. Grasping a black braided rope in one gloved hand, Craig and I followed the line back to the station, where we felt our way across the coral-and-algae-covered metal to the rectangular opening in the bottom known as the moon pool.
The station functions like an inverted glass pushed down into a bucket of water: An air pocket remains at the top of the glass while the glass remains upright. The crew maintains the air pressure inside Aquarius at the same high pressure as the surrounding ocean, keeping the water from rushing in. We lived in that air pocket, which I was eager to get back to. Emerging from the ocean water, I stood waist-deep in the moon pool, removed my regulator, and breathed in the hot, humid air from Aquarius.
"Generator's down," said Christian Petersen, a U.S. Navy diving medical officer, as he stood above me in the dim emergency lighting. Without power from either of the two electric generators in the life-support buoy tethered above us on the surface, we had only dim emergency lights and no air-conditioning. In these warm tropical waters, with a half dozen people inside, our small laboratory would rapidly become stifling. I climbed up the stainless steel steps, peeled off my dive gear, and began to sweat.
Technician Jim Buckley sent a radio distress call to the mission control team monitoring Aquarius ten miles away in Key Largo. Fortunately the team had seen the power outage on their computer screens and immediately had sent a speedboat to our rescue. Our six aquanauts—three scientists, a National Geographic photographer, a medical doctor, and a technician—stood shoulder-to-shoulder in the three-by-eighteen-foot corridor of the dry main living area, quietly and a little nervously waiting for help.
Forty-five minutes later, a crew from the National Oceanic and Atmospheric Administration's (NOAA) National Undersea Research Center finally arrived. Aquarius program technician Michael Hutchens popped his head up through the wet-porch door. "You guys all right?" he asked. Up above, the support crew cleared a blockage in the diesel engine's fuel line inside the life-support buoy, and our lives returned to "normal" in our home on the seafloor.
My mission at Aquarius was to track fish along coral reefs in the Florida Keys National Marine Sanctuary—one of 13 marine sanctuaries in the nation. As vice president for global marine programs at the New England Aquarium, I wanted to determine how far reef fish routinely swim during their daily migration. This was my third saturation mission in Aquarius, which was built in 1987 by the United States government to enable scientists like me to study the ocean by living on the seafloor. The big advantage in letting our bodies become saturated with nitrogen was that we could dive all day without risk of decompression sickness, as long as we didn't surface.
Owned and funded by NOAA and operated by the University of North Carolina at Wilmington, Aquarius has hosted more than 70 missions. About 200 scientists have used the lab to study ocean issues such as how global warming affects corals, the condition of deep coral reefs, and how the ocean might provide new pharmaceutical drugs.
Living in Aquarius was like a spaceflight, a submarine ride, and a week in a college dorm wrapped in one. Because of all the valves, electronics, bunks, carbon dioxide scrubbers, fresh water jugs, dive gear, computers, and cameras we needed, it got very cramped. As we navigated the 40 feet from the bunk room to the wet porch we were always bumping into each other, searching for a place to sit or stand. To eat our freeze-dried meals or use our computers, we took turns sitting at a small table. There was so little room for photographer Brian Skerry's gear that he had to sleep with his camera housings and strobes. Even without camera gear, the bunks were so small we could barely roll over. Nevertheless, at night as we lay sardine-like, packed 24 inches above and below each other, discussing the day's events, we found ourselves laughing uncontrollably at jokes that were mediocre at best.
At least we had an excuse: Breathing compressed air made us a little euphoric all the time. This "high," which feels like you've just had a glass of wine, is called nitrogen narcosis. It also causes occasional short-term memory confusion. Maybe it was narcosis or maybe it was the magic of living underwater, but time slipped by fast in our nonstop series of dives.
On my second morning in Aquarius, I was standing in the wet porch beside the moon pool, watching fish swim by in the clear blue water, when Boston University scientist Les Kaufman arrived from the world above. Rising up out of the water, he removed his regulator and mask, took a deep breath, and grinned.
Ahhh, the smell of home!" he said, his voice sounding squeaky.
The pressurized air in Aquarius is denser than surface air—the equivalent of two and a half atmospheres. You can feel that the air is "thicker" as you breathe it in through your nose and lungs, and it alters odors. It also makes your voice higher than normal.
"I saw a blue parrotfish in the trap on my way down here," Les said.
"OK, let's start with him," I replied. I squeezed into my wet suit, shrugged on my tanks, and slipped into the moon pool. We slowly sank to the sandy seafloor beneath Aquarius.
Our goal was to become the first team to surgically implant electronic acoustic tags underwater in a variety of reef fish and track them in real time from Aquarius. Les, a veteran of two previous missions at the station, had not saturated with us this time since he was needed for related work at the surface. His plan was to swim down each day and spend 90 minutes on each dive—an extension over conventional scuba techniques made possible by a special breathing mixture called nitrox.
Establishing an operating room for fish underwater was more challenging than we expected. We needed to learn new techniques for administering anesthesia, to communicate without speaking during surgeries, and to contain the fish during their recovery. But the extra effort was worth it. Performing the surgery underwater would minimize the physiological trauma to our patients since the fish would remain at their normal depth and pressure throughout the procedure.
Swimming beneath the research station, I inspected the dishwasher-size fish trap, made of wire mesh, that we used to catch our patients. With my dive mask pressed close to the trap I saw our first subject, an iridescent blue parrotfish, peering back at me. Pointing to the ten-inch-long fish, I made the OK sign to Les, and we both lifted the trap and swam it up to our work platform, which extended to the side of Aquarius next to the moon pool.
Our underwater operating room consisted of an 18-inch-long plastic gurney. After anesthetizing the parrotfish, we laid it on the gurney. Kneeling to do the surgery, Les carefully made a small incision, inserted an inch-long acoustic tag about the diameter of a pencil, and closed the incision with a simple suture. Whenever the fish moved a fin, rolled an eye, or expanded a gill during the 15-minute procedure, I administered more anesthetic, squirting the medication into the fish's mouth with a syringe and plastic tube. Then I gently cradled the fish until it awoke and swam off.
Later that day, after returning to Aquarius, I heard back from our parrotfish by a kind of e-mail. As I stood in the tiny lab, I watched as information on the fish's location, depth, and body temperature streamed onto my computer screen. Each acoustic pulse from the tag was like a message from our fish, which I learned from the data was about 300 feet south of Aquarius at a depth of 90 feet.
To confirm that the surgery had not harmed the parrotfish or altered its natural behavior, I asked aquanauts Craig Taylor and Ken Mallory to swim out into the reef that afternoon to locate it with portable acoustic trackers and visually check on the fish's recovery.
"Make sure it's swimming upright and eating normally, and check that the sutures are holding," I told them. They stayed with the fish for several hours, watching it swim and graze on algae that covered coral rock on the reef surface.
During the next six days we repeated the surgery 23 times, tagging seven different species: blue parrotfish, hogfish, Spanish hogfish, moray eel, nurse shark, red grouper, and black grouper. Using a pair of acoustic receivers, we tracked the movements of these fish through their coral reef habitat.
After one round of surgeries, in a rare moment of quiet after Les had returned to the surface, I was sitting at the small galley table in the main lock, sipping coffee and looking out the round view port at the mounded coral and schooling fish surrounding Aquarius.
"I hope our guys are OK," I thought, mulling over our recent procedures.
At that moment a six-inch-long Spanish hogfish, blue-violet and yellow, stopped outside the view port and gave me a wide-eyed look. Just then I heard my computer beep, as the fish's tag announced his visit. It was one of our former patients—healthy and full of life.
Our work at Aquarius was the fulfillment of a once futuristic dream. Forty years ago it was popularly believed that humans would routinely work and live underwater. Robert Sténuit became the first aquanaut to stay underwater in a pressurized environment for 24 hours, on September 7, 1962, after living at a depth of 200 feet in the Mediterranean Sea during a research project funded in part by the National Geographic Society. In 1963 U.S. Navy Capt. George Bond, using pressure chambers on land, proved that people could live under pressure and be decompressed safely. A rush of habitats followed, including Jacques Cousteau's Conshelf and the Navy's Sealab programs. All told, governments and scientific organizations around the world built more than 65 underwater habitats.
Noting the similarities between underwater habitat missions and space missions, NASA teamed up with the Navy and General Electric in 1969 to build the Tektite habitat. Aquanaut-astronauts spent up to 60 days living on the seafloor, at the time the projected length of future space missions.
The death of aquanaut Berry Cannon the same year from an improperly prepared rebreather during the initial stages of Sealab III ended the Navy's direct involvement. But underwater habitat programs continued until the 1980s. By then space exploration had proved better at capturing the public's imagination—and funding.
Eventually dreams of underwater cities were replaced by space stations, and all ocean research habitat programs except Aquarius ended. Now the underwater lab is once again attracting Navy interest and is also being used by NASA to train astronauts in the ocean equivalent of a space station.
After six days on the seafloor it was time to rejoin the world above. The habitat would now serve as our decompression chamber. Known as the "pay as you leave" method of diving, our saturation required us to decompress for 16.5 hours before returning to the surface. On the last day of our mission everyone came inside and the pressure door was sealed.
We lay in our bunks—reading, sleeping, and some of us worrying about how our bodies would handle the change in pressure—while breathing pure oxygen for three 20-minute periods. Then the pressure was slowly lowered in precise increments until the internal pressure was equalized to surface pressure. Finally the pressure would be briefly equalized to the surrounding ocean pressure again, making it possible for us to open the door and swim directly to the surface.
I was leaving Aquarius with a feeling of satisfaction. Our underwater tagging had been a success: The fish healed well and behaved normally without post-surgical ill effects. We had also learned that many of the fish did spend most of their time within a limited area. These early results lend hope that marine sanctuaries may prove to be one of our most effective tools for saving the oceans from the overfishing, pollution, and destruction with which humanity has bombarded them for many years.
But the oceans need more help. During the 20th century many fish populations declined by 90 percent, and virtually all marine habitats near human settlements were degraded in some way. Along with other technologies, and information from the ocean animals themselves, the underwater lab has helped show us what the oceans were meant to be like. By allowing us to live with the fish, Aquarius has opened a new window on the watery 70 percent of our planet. The spaceship on the ocean floor has become one of the oceans' best defenses.


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