Northwest Researchers Explore The Mysteries Of Eel City

By Christine Loftus

Deep-sea hydrothermal vents have become famous for harboring fantastic life forms–giant tubeworms, clams the size of dinner plates, blind shrimp, and about 300 other previously unknown species in habitats often described as otherworldly.

This summer, scientists were stunned once again by hydrothermal organisms: A population of hundreds of eels was found to live at a new undersea volcano off the coast of Samoa. This community, named "Eel City" by the astonished scientists who witnessed the eels emerging, is being studied by Craig Young, director of the Oregon Institute of Marine Biology at the University of Oregon, Eugene.

"We were astounded," says Young. "Many of us had worked on hydrothermal vents in other parts of the ocean and had never seen or heard of anything like this before." The May 2005 expedition was led by the Scripps Institute of Oceanography and the Woods Hole Oceanographic Institution; Young headed the biology group of the multi-institution expedition.

Unable to capture any eel specimens for study during that first expedition, Young and colleagues planned a return trip to better analyze the eels and their environment. Several pressing questions fueled excitement over the new expedition. "First, of course, we were interested in knowing the identity of the eels," explains Young. That is, they wondered if this was a new species completely unique to the hydrothermal vents, or whether the eels simply migratedfrom other deep-sea locations and into the warm vents of Nafanau, the newly-discovered volcano.

Regardless of the eels' origins, the researchers were most eager to discover how the population fit into the food chain. What was the animal's source of sustenance? "Because they were surrounded by thick mats of chemosynthetic microbes, the answer at first seemed obvious," recounts Young. Such microbial mats, consisting of unique bacteria that convert various chemicals into energy, are the standard food source for hydrothermal organisms.

"But when one of our team, Ray Lee of Washington State University, calculated the enormous amount of microbial mat the eels would have to consume in order to survive, we realized that the intuitive answer, eating bacterial mat, was probably impossible," says Young. "Since there were no other obvious food sources, this became an especially interesting scientific puzzle."

Answers to the puzzle may be coming soon. Young and collaborators completed follow-up visits to Eel City this summer and are currently preparing the results for publication and release to the public. As the secrets of Eel City are unraveled, more surprises from the ocean's bottom are sure to surface.

Christine Loftus is an adjunct instructor of chemistry at Seattle Central Community College and has studied science news writing at the University of Washington.

Image:

Purple eels, one to two feet in length, emerge from hiding places in the vent's rocky surface, covered with yellow microbial mat. Photo: Scripps Institute of Oceanography