OREGON STATE UNIVERSITY

OSU explorers to study seamounts, rock-eating microbes

06/25/2002

ASTORIA - A team of explorers, including five Oregon State University researchers, is sailing to the Gulf of Alaska to undertake a three-week study of the geology and rock-eating microbes of five unexplored volcanic seamounts.

Marine geologists from OSU's College of Oceanic and Atmospheric Sciences will be sampling the geology of the seamounts in a quest to determine how volcanic activity in the area varied over the course of millions of years, said Randy Keller, an assistant professor in the college.

Keller will then compare the data collected on the cruise to the presently active Axial Seamount, located about 300 miles west of Oregon's Cannon Beach. The Axial Seamount has been intensively studied and is now closely monitored by the National Oceanic and Atmospheric Administration's seafloor observatory, NeMO, he said.

Joining Keller will be OSU doctoral candidates in oceanic and atmospheric sciences, Chris Russo and Michael Rowe.

There are hundreds of underwater mountains or seamounts in the Gulf of Alaska, with some more than 9,900 feet tall, Keller said. Many of the seamounts occur in long chains that extend southeast from the Gulf of Alaska, down the west coasts of Canada and the United States.

The chains apparently formed as the Pacific Plate moved over a group of "hotspots" now off the coasts of Oregon, Washington, and British Columbia, Keller said.

The hotspots - points of frequent volcanic activity that persist over millions of years - appear to remain at fixed locations on the earth, while the tectonic plates on the surface move over them, he added.

As the Pacific Plate moves toward the northwest it acts as a conveyor belt and carries the seamounts northward as another seamount forms in its place. During millions of years this process results in the long seamount chains in the Gulf of Alaska, with the oldest seamounts at the northwest ends of these chains and the youngest at the southeast ends, Keller said.

As Keller and his team analyze seamount geology, Martin Fisk, an OSU professor of oceanic and atmospheric sciences, will study microbes that are attacking the volcanic rocks of the seamounts. Joined by Erin Bastian, an OSU junior in biology, Fisk will work to determine the abundance of microbes in the volcanic rocks of different ages and to determine what microbes are present.

Bacteria have evolved to scavenge chemical energy from many types of materials, and volcanic rocks from the deep sea appear to be one of these materials, Fisk said. A vast part of the ocean floor is composed of basalt that has erupted on mid-ocean ridge volcanoes or on isolated volcanoes that form seamounts.

This bacterial behavior raises many questions, such as: how do microbes dissolve the rocks, do the microbes obtain nutrients from the rocks, and do they obtain energy from the rocks, Fisk said.

Colonies of the microbes will be brought aboard the research ship and grown in cultures, which is the best way to determine how and why the microbes attack the rocks, Fisk said. Rocks from several old volcanic seamounts will be used to inoculate the cultures. The cultures will be sampled and analyzed after Fisk and Bastian transport them back to their OSU laboratory.

The pair knows microbes live in most environments where water is present and the temperature is less than 100 degrees C. Other requirements for life are carbon, essential nutrients, such as phosphorus and nitrogen, and a source of energy. For most organisms the sun is the primary source of life sustaining energy, but some microbes use the chemical energy of the earth to sustain them. One example is the microorganism that combines oxygen and hydrogen sulfide within the gut of tubeworms at hydrothermal vents, Fisk said.

He also notes that the habitats in volcanic rocks that microbes occupy on earth may be duplicated on other planetary bodies. Microbes that are capable of living in the deep ocean rock could potentially live in subsurface environments on Mars.

OSU researchers will be joining scientists from: Woods Hole Oceanographic Institution; Stanford University; the University of California at Santa Cruz; University of Alaska, Fairbanks and NOAA. The researchers departed Astoria on the NOAA Research Vessel Atlantis on Saturday, June 22 and expect to reach their first research area on June 26. The ship will return to Astoria on July 15.

The deep-sea submersible Alvin will be used at each seamount to collect samples and to develop a photographic inventory of benthic macrofauna during each dive. Comparisons will be made between seamounts, and depth transects will be conducted with the Alvin to examine depth distribution, habitat utilization and community structure of seamount organisms.

Reef-building deep-sea corals and sclerosponges will also be collected to determine their potential for providing information about climate and ecosystem variability in the Gulf of Alaska and the reproductive biology of some deep-sea coral samples will be examined. Species distribution and habitat utilization of deep-sea crabs will be examined and live samples will be collected to determine biological characteristics such as species, sex, and reproductive condition. A 'gentler' manipulator claw will be developed and tested on the Alvin to aid in the collection of live crabs. Observations will be made at various depth ranges where particular crab species are most abundant, to document reproductive or aggregative behaviors, as well as biological interactions with other species.