The secret (undersea) garden
May 25, 2002
by Lonny Lippsett

Twelve years have passed since scientists last visited the extraordinary communities of undersea life thriving around hydrothermal vents in the Galápagos Rift. How has the neighborhood changed since then?

Vent animals were first discovered 25 years ago here. Two years later, when biologists got their first chance to investigate, they saw a wondrous sight. A mass of tubeworms—too many to count—with their blood-red tips peaking out of long, narrow, bright white tubes. They swayed in the slow ocean-bottom currents like a field of flowers in the wind. The scientists called the site “Rose Garden.”

Six years passed until oceanographers could return again. In 1985, Bob Hessler of Scripps Institution of Oceanography described a different scene in the Rose Garden. An army of giant clams had invaded. Great clumps of clams and a few mussels piled up beneath the tubeworms’ white stalks, crowding out the tubeworms. By 1990, the last time scientists visited Rose Garden, clams and mussels had taken over. Only a few bouquets of tubeworms remained.

Like any community of living things, circumstances change over time. Imagine if you returned to your neighborhood 12 years from now. Perhaps another family has moved into your old neighbor’s house. Your neighbor's barking dog is gone. But some things—like the tree you used to climb, or your old basketball hoop—might seem just the way you left them.

Hydrothermal vent sites are ever-changing. They are fueled by volcanic heat from deep within the Earth. That heat can fade out or be turned up, and the whole environment changes. The amounts of hydrothermal fluids emitted from vents site may increase or decrease. Their temperature can go up or down. Their chemistry changes, and with that, the amounts and types of microbes that use these chemicals to live also changes. And as the microbes change, so do the large animals (or megafauna) that eat different microbes.

How do all these changes affect the communities of animals that live around vents? Why do some types of animals thrive at some times, or in some places? How do the different animals interact with each other and with different microbes? How do communities start, grow, change, die and get reborn?

Tonight, we dispatched to the seafloor two transponders, whose sonar “pings” will serve as landmarks to guide our deep-sea vehicles in the dark ocean bottom. But first, Pat Hickey, Expedition Leader, scanned the seafloor with sound—just to ensure that no other active transponders were inadvertently left in the area. (Their signals would confuse our vehicles.)

ABE, the Autonomous Benthic Explorer, was launched to map the Rose Garden area. Sometime after midnight, Bob Collier and John Lupton will deploy the CTD over the Rose Garden to see if this area is still venting warm hydrothermal fluids. Tomorrow morning, Tim Shank and Steve Hammond, the expedition’s Co-Chief Scientists, will descend in Alvin to return to the Rose Garden.

“It could be completely dead and long gone and wiped out,” Tim said. “Or maybe there was a volcanic eruption last year, and the hydrothermal cycle began again, and it’s reinvigorated.”

We have traveled 275 nautical miles in the past 30 hours to arrive at 86°W, where hydrothermal vents were first discovered. We will read the next chapter in the history of a place that made history.

On Sunday, we'll all find out if the bloom has faded in the Rose Garden—or if it has blossomed again.

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