Famed undersea vent may be lost. (Oceanography).

When scientists last month tried to revisit an undersea hydrothermal vent that was first discovered nearly a quarter of a century ago, they were in for a shock. Instead of finding a thriving ecosystem nourished by warm, mineral-rich waters spewing from the ocean floor, the researchers came across a desolate, almost lifeless place.

This hydrothermal site is one of a group of such venues discovered under more than 2,400 meters of water about 400 kilometers northeast of the Galapagos Islands. Scientists nicknamed this particular vent the Rose Garden when they found it in 1979 because of the 2-m-tall, red-tipped tube-worms surrounding the seafloor springs.

Biologists returned to the Rose Garden in 1985, 1988, and 1990 to observe how the ecosystem there had changed. On a series of dives that began May 24, however, scientists found that all hints of the vent system had disappeared beneath apparently fresh volcanic lava.

While scouring the area for clues to the Rose Garden's disappearance, the scientists found a new vent system, which they've dubbed Rosebud, about 350 m to the west. There, biologists found 60-centimeter-long tube worms, 7-cm dams, and other animals that appear to be the same species as those that previously lived at Rose Garden but are much smaller, says Fred Grassle of Rutgers University in New Brunswick, N.J.

The Rosebud animals could be young creatures that haven't had time to reach full size at the new vent. It's also possible that the animals are dwarf species similar to those at Rose Garden or that the Rosebud vent simply isn't providing as much nourishment as Rose Garden did, Grassle says. Detailed analysis of specimens and water samples from the new vent may provide more information about what happened at Rose Garden in the past dozen years. --S.P.