On most reefs around the world, the abundance of hard coral has declined, and the cover of soft algae has increased, said Steve Gittings, science coordinator with NOAA's National Marine Sanctuary Program. Algae is a natural part of the ocean ecosystem, but it can respond to human influences such as pollution to create large or unnatural concentrations that can displace corals.
Researchers also want to learn more about two other reef dwellers, sponges and soft corals, because it's not clear whether their abundance has significantly changed, Gittings said. Also of interest are the suspected causes of change in reef ecosystems, which may include a mass die-off of a long-spined sea urchin that ate algae, Gittings said.
"We're seeing dramatic changes literally on reefs around the world with regard to the relationship between all those different components that live on the bottom," Gittings said.
One of those components is sponges, which pump water through their bodies to filter food particles and produce dissolved nitrogen, a fertilizer.
The Aquarius team will investigate any links between changes of reef compositions and organic matter processed by sponges, seeking to discover whether sponges are fertilizing grasses that compete with corals, said researcher Chris Martens of UNC-Chapel Hill.
"Corals have gone through huge changes in terms of being totally dominant in oceans to being lesser," said Martens. "We're asking the question, `Do sponges help or hurt in that process?'"
Aquarius, owned by the National Oceanic and Atmospheric Administration, operated by the University of North Carolina-Wilmington and used by the Navy and NASA, was built in 1986. It began operating in the U.S. Virgin Islands before being redeployed off Key Largo in 1993.
The facility has bunk beds and showers; a microwave, refrigerator and sink; and the computer and diving equipment needed to research reefs and collect, assemble and relay data.
"It's not claustrophobic, really," said Prager, the chief scientist.
Food, computers and other equipment are sent down using pots that can handle 2 1/2 times normal atmospheric pressure below the ocean's surface.
After the expedition, the aquanauts must decompress for 17 hours or they will get the crippling "bends."
"We don't want to fizz," Martens said.
A surface buoy provides air, power and communications to Aquarius through hoses, cords and cables. On land, a crew monitors the living conditions in the facility.
The aquanauts eat microwaved or reconstituted meals. Food must be sent down via the special pots or it will not stand the pressure.
"A Pringles can can turn into a pretzel," Martens said.
Eating is one of the things about living underwater that takes some adjustment, Prager said.
"Things tend to taste very bland," she said. "There's a lot of hot sauces down there."
On the Net:
OceansLive:
http://www.oceanslive.org
Aquarius:
http://www.uncw.edu/nurc/aquarius
Virtual Dive to Aquarius:
http://oceanexplorer.noaa.gov/techno.../aquarius.html
NOAA's National Marine Sanctuary Program:
http://sanctuaries.noaa.gov