Dive and Discover : Expedition 9

Dive and Discover's Expedition 9 returns to the Galápagos Rift, located on a mid-ocean ridge about 250 miles from the Galápagos Islands where hydrothermal

vents and exotic organisms were first found in 1977. In 2002, researchers diving in the submersible Alvin discovered that seafloor lava

had paved over a hydrothermal vent site called Rose Garden, wiping out large communities of tubeworms, mussels, and other animals living there. Rose Garden was gone, but further exploration in Alvin revealed that life still flourished. A few hundred meters away, tiny animals had begun to colonize a new vent field in the aftermath of the volcanic eruption. Researchers named the field Rosebud.

From RV Atlantis, researchers will again use Alvin to see how the animal communities have developed and what chemical, microbial and geological changes have occurred. They will make detailed maps of the animal distributions, take high-resolution photographs to create photomosaics of the seafloor, sample the animals and lava flows, as well as deploy time-lapse cameras, larval traps, and chemical sensors directly at the vents. They will also search for new animal communities and black-smoker

vents along still-unexplored areas of the Galápagos Rift.

As part of the National Oceanic and Atmospheric Administration (NOAA) Ocean Exploration Program, scientists on Expedition 9 will build on knowledge gained from previous expeditions to learn how the Rosebud hydrothermal vent community has changed.

Objectives
Expedition 9 returns to the Galápagos Rift to see how young, deep-sea vent organisms living on a recently erupted lava flow have grown and changed since they were discovered in 2002, on Dive and Discover's Expedition 6. Researchers aboard the research vessel Atlantis will travel to the mid-ocean rift valley in the eastern Pacific Ocean, located at 86°W.

Using the human-occupied submersible Alvin, deep-sea cameras, and specialized chemical and biological sensors, researchers will spend two weeks exploring and studying the hydrothermal vents. The vent site, named Rosebud for the young community of animals found living there, is located 2,600 meters (1.6 miles) below the sea surface. The home of these animal communities is a dark, volcanic undersea valley about 4 kilometers (2.5 miles) wide.

A nearby site, called Mussel Bed for its massive colonies of mussels, will also be explored. It has been 15 years since scientists have visited Mussel Bed, and they are eager to see if—and how—the area has changed.

Understanding survival in the deep sea
In the 28 years since hydrothermal vents were discovered along mid-ocean ridges, scientists are still puzzling over how tubeworms, clams, mussels, and other organisms populate these deep-sea oases. Tim Shank, a biologist at WHOI and the Chief Scientist of Expedition 9, calls deep sea vents “Earth’s largest chemosynthetic community,” where inhabitants live without sunlight. Instead they use dissolved gases in vent fluids as their energy source.

“There’s no other place on the planet like this, yet we know little about how young organisms living there colonize, assemble, and form new communities,” he said. So understanding the factors that determine why animal larvae settle there is a key first step to understanding the bigger picture of how seafloor life has developed across the wide expanse of the ocean, and throughout time.

Tim was diving in Alvin in 2002 when he observed that a long-studied hydrothermal vent field called Rose Garden, known for hosting lush communities of animals, had been paved over by a lava flow. Days later, he was also among the scientists who identified the new vent field, Rosebud.

Team work for science
The changes at hydrothermal vents involve many different, interrelated organisms and processes. On Expedition 9, scientists will work as a team to figure out how vents and vent life interact and operate.

Biologists will look at the ways in which the larger animals at the site, called macrofauna, have evolved over the past three years. After collecting and trapping samples of seafloor larvae, Tim, Stace Beaulieu and other biologists from WHOI will look at the animals’ genetic composition. They will compare this with genetic data of adult animals from the site.

Chemists will use state-of-the-art chemical sensors, developed by scientists Bill Seyfried and Kang Ding at the University of Minnesota. Their instruments, which will make measurements 24 hours daily for duration of the cruise, will assess some of the key chemical properties of the venting fluids to get a clearer picture on how vent chemistry influences the larvae’s settlement.

Microbiologists Naomi Ward and Kevin Penn of The Institute for Genomic Research will collect microbe samples from rock surfaces and vent animals, and use genetic techniques to identify microbes where vent animals colonize. This information will help them understand the role that microbes play in the evolution of hydrothermal vents.

Geologists will collect rocks and make seafloor maps using observations, photographic, and bathymetry data collected by Alvin. At night, when Alvin resurfaces to charge its batteries, WHOI geologists Dan Fornari, Susan Humphris, and Adam Soule will slowly tow a digital deep-sea camera system—the WHOI TowCam—above the seafloor to map the extent of lava flows. The information will help them to better understand the volcanic and tectonic history of this part of the rift valley and how it relates to the hydrothermal venting.

Each day will bring new samples, new discoveries, and new ideas about how hydrothermal vents at the Galápagos Rift have changed since they were first discovered, and new insights into how life evolves in these extreme environments on the deep-sea floor.