UVic scientists explore Ring of Fire
Research team enters the other-wordly
realm of active volcanic seamounts
by Valerie Shore
Billowing clouds of volcanic ash and molten sulphur, forests of "black smoker" chimneys up to nine metres tall, plumes of liquid carbon dioxide bubbles, and countless lifeforms that are likely new to science.
Sound like another world? In a sense it is. These are just a few of the remarkable, never-been-seen-before underwater spectacles that greeted UVic ocean scientists Drs. Verena Tunnicliffe and John Dower on a recent research cruise to the "Submarine Ring of Fire," or Mariana Arc—a 1,200 km chain of volcanic seamounts and islands in the western Pacific between Guam and Japan.
Tunnicliffe and Dower were part of a 34-member international expedition sponsored by the National Oceanic and Atmospheric Administration (NOAA) Ocean Exploration Program, a scientific and educational outreach program. The two-week expedition used ROPOS—the Canadian submersible partly funded by UVic and housed in Sidney—to explore hydrothermal sites and collect images and samples of vent fluids, unusual life forms, and mineral and volcanic rocks.
Tunnicliffe is a leading authority on deep sea life and the Canada Research Chair in deep ocean research. Dower has been studying physical-biological interactions in seamount ecosystems for the past 10 years. They and three other Canadian researchers represented the biological contingent on the cruise. The team and ROPOS were funded by the Natural Sciences and Engineering Research Council.
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Tropical fish swimming in an area of hydrothermal venting |
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A big surprise was how the marine life at every hydrothermal site differed. One was blanketed with barnacles, the next with limpets, and another with mussels. This contrasts with hydrothermal vents on the Juan de Fuca Ridge in the northeast Pacific, which show comparatively little variation from site to site.
"The distance between any two Mariana sites we explored was less than 100 km, so you'd think they'd be connected by ocean currents to move animals back and forth. Yet they were completely different," marvels Dower. "Each seamount is a separate ecosystem in terms of its composition and the geological, chemical and biological forces that drive it."
"These seamounts are key sites for fostering the importance of biodiversity in the oceans," says Tunnicliffe, who has collected biogeographic data from hydrothermal vents all over the world. "I'd planned beforehand what I was going to work on, but found very little of what I expected. Each site presented a whole new suite of organisms."
Among other discoveries was an underwater volcano where sunlight-based and chemical-based ecosystems overlap. Images clearly show shallow-water reef fish swimming among black smoker chimneys. "This is the first place in the world where scientists have documented interactions between these two ecosystems," says Dower. "When they called this trip an exploration, they weren't kidding."
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White chimneys and CO2 bubbles at "champagne" vent site |
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For Dower, the most exciting moment was watching an underwater volcano erupt. He was on video monitoring duty when roiling clouds of yellow "smoke" spewed out of a pit crater being explored by ROPOS.
"Like real science geeks we all sat there for five minutes saying ‘Wow, this is really cool," until someone said, ‘I think it's erupting' and that perhaps we should leave," recalls Dower. When ROPOS was brought to the surface it was coated with blobs of pure sulphur.
Another extraordinary moment came at a site dubbed the "champagne vent" where large, viscous bubbles of liquid carbon dioxide were rising out of the sediment. "They didn't behave like gas bubbles, which just stream upwards," says Tunnicliffe. "They wandered around and turned into funny shapes, sort of like liquid mercury. They stuck all over ROPOS."
So relentless were the new discoveries—and the pace to collect specimens and record images—that team members got little rest. On the last night, Tunnicliffe was yanked out of bed at 3 a.m. to view yet more amazing live video. "We could see these funny little blobs like sticks on the bottom," she says. "They were flatfish, thousands and thousands of them piled on top of each other. I've never seen anything like it. It was incredible."
Not surprisingly, both researchers hope to return to the Mariana Arc very soon.
"It was a wonderful trip," says Tunnicliffe. "I've been to a lot of amazing places, but this reminded me how little we know about the oceans and that there are still a tremendous number of discoveries to be made."
A detailed expedition log, video and images are available on the expedition Web site at: oceanexplorer.noaa.gov/explorations/04fire/welcome.html. |
