Mission
This spring, join Expedition 8 of Dive and Discover as researchers diving in the submersible Alvin explore hydrothermal vents off the Pacific Northwest coast. During the 17-day expedition to the Juan de Fuca Ridge, 200 miles west of Washington state, scientists and engineers will deploy new ocean instruments and gather samples of fluids and organisms from the vents to learn how microbes live in this high-pressure, super-heated environment.

Scientists will focus their research on hydrothermal vents at the Mothra and Main Endeavour Fields, more than a mile beneath the ocean surface. Last year, scientists identified a heat-loving microbe from the Mothra Field that thrived at 250 degrees Fahrenheit (121°C), a temperature that no other life form is known to tolerate. These microscopic creatures may be similar to the earliest forms of life on Earth, which also tolerated high fluid temperatures, little oxygen, and used iron for metabolism. Finding microbes that can survive such extremes increases the possibility of life existing on other planets or elsewhere in the universe.

Deeper Discovery

Researchers on Expedition 8 will travel to a long, narrow undersea volcano known as the Endeavour Segment. This unusual volcano is just over 650 feet (200 meters) in height, but its width extends nearly two and one-half miles (4 km) and its length stretches nearly nine miles (15 km). It is part of the Juan de Fuca Ridge, the mid-ocean ridge in the northeast Pacific Ocean located about 200 miles west of Seattle.

The central area of this volcano contains five of the planet's most active hydrothermal vent fields, places where water seeps through cracks in the seafloor and is heated as high as 716°F (380°C) by hot rock deep below the ocean crust.

Last summer, scientists from the University of Washington (UW) and the Monterey Bay Aquarium Research Institute (MBARI) placed instruments called microbial incubators inside the walls of three black smoker chimneys in the Mothra and Main Endeavour vent fields, two of the five vent fields along the Endeavour Segment. Sensors within the instruments have measured temperature every 20 minutes during their year-long deployment, collecting about 700,000 temperature measurements.

Microbes that live inside the chimneys are also growing within these incubators. During Expedition 8, researchers diving in the submersible Alvin will recover the instruments and the microbes inside.

"We are excited, but also a bit nervous about getting the instruments back," says Deb Kelley, a University of Washington researcher and the chief scientist on the expedition. "They are the first instruments of their kind, and this will be their first long-term test within these extreme environments."

Answering big questions
Investigating the high temperatures that support microorganisms thriving in super-heated, seafloor environments helps researchers to answer big questions about life on Earth. Their work will aid in determining how microorganisms can live beneath the ocean floor, for understanding how and where life might have began and evolved on the planet, and will help to explore the possibility of similar life forms surviving with little oxygen in extreme environments on other planets in the solar system.

Last year, scientists studying black smoker chimneys collected from the Mothra vent field identified microorganisms growing at the highest temperature known to maintain life on Earth: 250°F (121°C).

"We believe that organisms can grow at much higher temperatures," says Kelley. "On this expedition, we want to begin to test this hypothesis."

Once divers in Alvin retrieve the instruments, researchers onboard the support ship RV Atlantis will continue to grow the microorganisms to determine how they live in various temperatures and pressures, and to study the gases and organic compounds they tolerate. Researchers will also examine their genetic makeup, metabolic processes, and what they eat to survive. At least one incubator will be redeployed back into the chimney walls so that researchers can investigate how long it takes microbes to colonize. They want to find out which of the organisms are the first to grow.

Earthquakes, maps, and cleaning up
In addition to investigating life within the chimney walls, scientists will take water samples from black smokers in at least three vent fields to see how the chemistry of the fluids and gases have changed since a series of undersea earthquakes shook the area in 1999. Using a special water sampler, they will take fluid samples from both high- and low-temperature vents. Scientists hope that these samples will help them understand how changes in fluid chemistry may influence changes in the microbial communities over time.

To help scientists visualize the topography, or bathymetry, of the seafloor around the vents, a sonar system on Alvin will be used to make a very detailed map of the surface of the seafloor. Like a road map, the image will reveal the location of faults, fissures, and vents within the vent fields to help scientists understand how the hydrothermal system formed.

A few Alvin dives will be spent cleaning up the Main Endeavour vent field. This region, located in Canadian waters, is part of a marine protected area, similar to an underwater national park. During nearly three decades of research at this site, tether lines, markers, and other materials have been left on the seafloor. Removing these will make future experiments and navigation in Alvin easier, and will keep the area free of debris left by humans.

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