Dive and Discover : Expeditions to the Seafloor

Twenty-five years ago, scientists made a stunning discovery on the bottom of the Pacific Ocean that forever changed our understanding of our planet, and life on it. They discovered the first deep-sea hydrothermal

vents, and—to their complete surprise—a lush community of exotic life thriving around them.

Dive and Discover’s Expedition 6 returns to the Galápagos Rift, where seafloor hydrothermal vents were first found in 1977. The discovery of vents spewing warm, mineral-rich fluids into the ocean helped explain why the ocean is salty and how our planet ventilates its great internal heat. The astonishing ecosystems

nourished by the vents revolutionized scientific thinking about where and how life could exist.

As part of the National Oceanic and Atmospheric Administration (NOAA) Ocean Exploration Program, scientists on Expedition 6 will return to see how the Galápagos Rift hydrothermal vent communities have changed. They will carry out detailed mapping and sampling, and search for new animal communities and black-smoker vents along still-unexplored areas of the Galápagos Rift.

Join scientists, students, engineers and the ship’s crew on board Woods Hole Oceanographic Institution’s RV Atlantis as they use the submersible Alvin, an autonomous underwater vehicle named ABE, and the latest in high-tech oceanographic instruments. They will explore the site that made history 25 years ago and search for other sites of hydrothermal activity and animal communities.

Objectives
Expedition 6 returns to the Galápagos Rift at 86°W, where oceanographers in 1977 made one of the most revolutionary discoveries about our planet -- deep-sea hydrothermal vents. A main objective of this cruise is to investigate how the vents and their animal and microbial communities have changed over the past 25 years.

Hydrothermal vent areas are among the most dynamic, constantly changing places on Earth. They are fueled by the heat of magma welling up from Earth’s mantle and erupting on the seafloor. As the heat varies, different chemical reactions take place between seawater and hot rocks in the ocean crust. As the heat and available chemicals change, so do the types and amounts of microbes that feed on the chemicals. And that affects populations of higher animals that either feed on the microbes or symbiotically maintain them inside their bodies.

The changes at hydrothermal vents involve many different, interrelated organisms and processes. So Expedition 6 will have many different types of scientists, working together, to figure out how vents and vent life interact and operate.

Several types of biologists will be aboard. Ecologists will study changes in Galápagos Rift vent communities that have occurred over the past 25 years, and how animals interact with each other. Microbiologists will study microbes, which use harsh chemicals in vent fluids as sources of energy. Geneticists will sample animal tissue to analyze their DNA and RNA and compare how Galápagos vent animals are related to animals elsewhere on mid-ocean ridges in the Pacific, Atlantic, and Indian Oceans. Chemists will study changes in the chemical composition of the Galápagos Rift hydrothermal fluids over the last 25 years. Geologists will analyze data on board to map the vent sites and see how they compare to other vent areas around the world.

Expedition 6 scientists will primarily use the deep-diving submersible Alvin to study the vents and sample vent animals and fluids. They will also use ABE, the Autonomous Benthic Explorer, to produce highly detailed maps of seafloor and to search for new vents.

An important objective of Expedition 6 is to explore other regions of the Galápagos Rift, 200 nautical miles west of the original vent sites, where volcanic eruptions may have occurred recently. Scientists will search for black smoker chimneys, whose fluids are hundreds of degrees Celsius hotter than those emanating from the vents at 86°W. Black smokers have been found at deep-sea vent sites elsewhere on Earth, but not on the Galápagos Rift.

To search for new vents, scientists will use sensitive instruments called CTDs (stands for Conductivity, Temperature, Depth) and MAPRs (Miniature Autonomous Plume Recorders) to look for the plumes of slightly warm and particle-rich water that rise from hydrothermal vents -- just like columns of vapor rising from smokestacks. In the dark depths of the oceans, these instruments can “see” cloudy water and can detect small telltale differences in the temperature and other physical properties of the water. They will also use a new, digital deep-sea camera system to search for new vents and to scout out new areas for Alvin and ABE to investigate.

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.