In the Depths of Aquarius
Mark Hay checked his scuba gear one last time, then stepped off a boat and dived toward the seafloor. His destination was Aquarius, the only manned underwater lab in operation in the world. The metal structure—about the size of a school bus—is anchored 60 feet beneath the surface near a flourishing coral reef a few miles off Key Largo...
Dr. Hay has been on a quest to find out if there is any tangible benefit to preserving a large number of species from extinction, and he has done key aspects of his research during stays here at Aquarius.
Marine researchers like Dr. Hay are drawn to Aquarius because they can conduct experiments on the deep reef for nine hours each day or night without fear of getting the bends—a potentially dangerous buildup of nitrogen in the blood that forces divers to limit the length of a dive.
Plus, the views aren't bad. On a recent visit, yellow damselfish peered through a porthole and a mean-mouthed barracuda lurked nearby. "You're in this reverse aquarium—an air bubble with windows," said Saul Rosser, operations director of Aquarius.
But the scuba-dive commute isn't the only reason it can be a tricky place to work. Scientists—or "aquanauts"—stay for 10 days at a time, living, eating and sleeping in the confined habitat. The high-pressure atmosphere in Aquarius means soda cans brought down barely fizz when opened. But food cans get squeezed and distorted. A person's voice also tends to have a different timbre. Whistling is hard.
At the end of each mission, the interior pressure is slowly reduced until it becomes the same as that on the surface. Aquanauts can then safely return to the surface without fear of the bends.
The lab has six bunks and a shower, and the food is of the astronaut variety. The "outhouse" toilet attached to the lab isn't fun. For starters, you have to swim to it, even if in the dark. A person must stand in the gazebo-like structure, breathing from an air pocket in the upper section of the structure. Waste disappears into the sea.
There are phones, computers and a wireless link to shore. During a mission, a land-based "watch desk" constantly monitors the habitat's vital signs—including pressure and oxygen levels—while also keeping an eye on the aquanauts via video cameras.
Aquarius is owned by the U.S. National Oceanic and Atmospheric Administration and is funded largely by a roughly $2 million annual grant from the U.S. government. The habitat is run by the University of North Carolina Wilmington, and has been used for 119 missions since 1992.
The reef base draws astronauts, too. The National Aeronautics and Space Administration has used Aquarius for 14 training missions to acclimate astronauts to isolated, extreme environments and conduct outside drills that mimic spacewalks.
Dr. Hay's focus is biodiversity, an issue that has become urgent. A recent study in the journal Science found that a fifth of all vertebrates are threatened with extinction. A July paper in Nature found that warmer oceans were altering marine diversity patterns. Sea plants are in decline.
"You hear about species loss all the time," said Dr. Hay, a biologist at Georgia Institute of Technology, as he sat at the small dining table at Aquarius during his recent visit. "The question is, if you've got a thousand species and you lose one, does it make any difference?"
Dr. Hay's underwater research may provide only a snapshot of a complex global problem, but it offers vivid evidence of why biodiversity matters. On a reef, for example, "it's not enough to have herbivores but the right mix of herbivores," said Dr. Hay. "If you remove one particular fish, things can quickly go to hell."
Dr. Hay's mission is to observe the fish. In a previous Aquarius experiment, his team built large undersea cages on sections of the reef, and stocked them with a varying mix of herbivores, including parrot fish and surgeon fish.
Herbivorous fish that eat algae are important to coral reefs because if algae proliferate, the corals die and the entire reef ecosystem is damaged. When Dr. Hay placed two surgeon fish in a cage, for example, 22% of corals died. But cages with one parrot fish and one surgeon fish—a greater diversity—showed no coral death and a 22% increase in coral growth over 10 months.
Dr. Hay's results were published in the Proceedings of the National Academy of Sciences in 2008. He believes that because different species have very different feeding habits on the reef, it helps to maintain the ecological balance and give corals a greater chance to grow. Humans are now upsetting that balance, he says.
Such research "is starting to tell us that we do need a mix of species or we run into problems," says Paul Snelgrove, a professor in the Ocean Sciences Centre at Memorial University of Newfoundland, Canada. "What we don't know is if there are key species [vital to an ecology] or biodiversity itself—there hasn't been enough work to tease apart those issues."
In November, Dr. Hay was set to embark on another Aquarius mission, to install new fish in a new set of 32 cages and study a different mix of herbivores over 10 months. But the mission got canceled over a safety issue. (The Aquarius operating team has become more skittish about safety since a diver died during a mission in 2009.)
So Dr. Hay's team reverted to doing things the old way—lowering cages by boat and coming up after each dive. Over the next 10 months, the scientists plan to dive to the cages once every six weeks to observe the changing health of the coral under the influence of a varying mix of fish species.
Such findings about biodiversity can help with reef protection. Says Dr. Hay: "By manipulating a few key fish species, we may be able to help reefs recover."