9:53 a.m., June 29, 2009----Three University of Delaware College of Earth, Ocean, and Environment (CEOE) students, one former student, and Maxwell P. and Mildred H. Harrington Professor of Oceanography George Luther recently completed a research cruise to the South Pacific, returning with a greater understanding of the relationships between the chemistry of deep sea hydrothermal vents and the organisms living there.

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Luther, students Amy Gartman, Andrew Madison and Mustafa Yucel, and CEOE alum Dominique Cowart were part of a FLEXE research cruise to the Lau Back-Arc Basin, near the Kingdom of Tonga.

FLEXE, short for “From Local to Extreme Environments,” is a National Science Foundation-funded effort in which scientists and educators connect students from around the world with the remote, extreme environments of hydrothermal vents. Cruise leaders included Luther and scientists from Penn State and Harvard universities.

Hydrothermal vents, located deep below the ocean surface, are among the most extreme environments on the planet. At these seafloor geysers, superheated water full of toxic chemicals seeps out of tall rocky structures known as “chimneys.” Water temperatures at vents can exceed 572 degrees Fahrenheit (300 degrees Celsius), while the surrounding bottom water is a cool 36 degrees Fahrenheit (2 degrees Celsius). No sunlight reaches this depth, where the pressure is almost 300 times greater than at sea level.

Despite the harsh conditions, organisms do survive the scalding water, toxic chemicals, and total darkness of hydrothermal vents. Unlike other hydrothermal vents in the eastern Pacific Ocean off Central America where tubeworms are the norm, the animals at Lau Basin in the Southwest Pacific are mostly shellfish, with two types of snails and a single mussel species the most common.

With the help of a remotely operated vehicle (ROV), Luther's team used a probe to make temperature and chemistry measurements at different positions near the vent. Their measurements show that different animal species prefer different water chemistry conditions.

This was Luther's third visit to the area. He noticed some changes in the biology and chemistry of sampling sites since 2006. For example, two of the sites visited previously were populated primarily by a species of white snail, but on this latest visit, a black snail species and a type of mussel were the dominant species.

“The white snail appears to be a pioneer species,” said Luther. “As the site cools down and the sulfide concentrations get lower, the mussels are the last of these species to move in. This biology and chemistry seem similar to past observations in the eastern Pacific,” where tubeworms are the pioneer species that eventually become outnumbered by mussels.

While located far from land, the scientists were far from isolated. Their work was followed by middle and high school students in the United States, Thailand, Australia, and Germany as part of the FLEXE project. Students were able to interact directly with the researchers with a live phone call. Researchers also posted blogs and photos directly from the cruise.

“Our interaction with the middle and high school students was a lot of fun,” said Luther. “They asked great questions on topics including the ROV and its operation, the biology and chemistry of the areas we studied, pirates on the high seas, and what life is like on our research vessel. The accounts that we received from the coordinators back in the U.S. indicated that the phone call went exceptionally well.”

Article by Ron Ohrel
Photos by Eric Simms