An orange roughy glides over an undersea mountain, or "seamount," located off the eastern coast of New Zealand in a 2006 picture.
Results from a five-year project to document and study the world's seamounts, called CenSeam, were released this week. The project is part of a larger endeavor, the decade-long Census of Marine Life, which aims to document all ocean flora and fauna. The census's final summary of up to 230,000 species will be released October 4.
CenSeam brought together more than 500 scientists, policy makers, and conservationists from around the world to study the types of marine life that make their homes on seamounts and how the creatures are affected by human activity.
With CenSeam, seamount researchers finally have a way to pool their results and coordinate their projects, noted Karen Stocks, a CenSeam scientist at the University of California, San Diego.
"Historically, seamount research hasn't been coordinated at all," she said. "There would be an expedition, they would go to an individual seamount or seamount chain, and publish their results."
Photograph courtesy NIWA
A bright orange brisingid starfish on a seamount in the Macquarie Ridge near New Zealand raises its arms to feed in 2008.
Like underwater cities, seamounts sometimes are home to much higher populations of marine life than the surrounding seafloor, CenSeam scientists have found.
The rocky surfaces on many seamounts offer a hard substrate for corals to attach to. Once a sizable coral population has been established, other creatures—such as sponges, sea anemones, starfish, and fish—can move in.
But such seamount communities are very disturbed by fishing and are slow to recover, CenSeam researchers have demonstrated for the first time.
"It was pretty obvious that bottom-trawling was going to have a substantial impact on seamount communities, but it hadn't been scientifically proven," CenSeam's Stock said.
For example, in one study, CenSeam scientists compared photographs of seamounts that had been trawled by commercial fishing with those of unfished seamounts.
They found that about 20 percent of the unfished seamounts were covered by coral, while fished seamounts had less than one percent of coral coverage.
Photograph courtesy NIWA
A crowded assemblage of deep-sea sponges and corals—including a large orange primnoid sea fan—are seen on the Macquarie Ridge seamount in 2008.
CenSeam researchers have determined that seamounts might serve as sanctuaries for marine life during periods of extreme environmental events, such as climate change-induced ocean acidification.
"In the future, seamounts might act as repositories of biodiversity," CenSeam's Consalvey said.
"They're undersea mountains that stick up from a flatter terrain, so they offer a variety of different depths. So if you've got a change of conditions, animals can find refuge up or down their slopes."