Dive and Discover’s first expedition of 2001 will be a 40 day long voyage to explore for hydrothermal vents at the mid-ocean ridge in the central Indian Ocean, one of the most remote places on Earth. Like 16th century explorers who traveled across the Indian Ocean in search of new lands and exotic spices, the scientists and crew on Expedition 4 will search for new hydrothermal vent animals and ancient bacteria -- missing links that can help explain how the fauna living at hydrothermal vents in the Atlantic and Pacific Oceans are genetically related.

Since hydrothermal black smoker vents were first discovered in 1979, on the East Pacific Rise off the west coast of Mexico, scientists have discovered that the communities of animals along the mid-ocean ridges are very different in the Pacific and Atlantic Oceans.

Because deep water in the ocean flows from the Atlantic, into the Indian Ocean, and then into the Pacific, the Indian Ocean provides the link. Are the same types of vent animals present at Atlantic and Pacific vent sites also found at Indian Ocean hydrothermal vents? How do these animals and their larvae migrate along the 60,000 km long global mid-ocean ridge system, and how do they get across the deep fractures, or transform faults, that separate segments of the ridge crest? Are there specific genetic differences between vent animals and the bacteria they eat that can help explain how hydrothermal vent fauna first evolved, and how they relate to the evolution of early life on Earth?

Now, a team of biologists, microbiologists, geneticists, chemists, and geologists from eight US universities and institutions will board the research vessel RV Knorr of the Woods Hole Oceanographic Institution (WHOI) in the Seychelles Islands to set out to answer these questions. The scientists will work with the ship’s crew and technicians from WHOI’s Deep Submergence Operations Group (DSOG) who will operate the deep-sea vehicles (including the Argo II mapping system, the DSL-120 sonar, and the remotely operated vehicle (ROV) Jason) to survey and sample the hydrothermal vents. Other equipment, including a CTD water sampling system, will also be used to help find hydrothermal vents.

The first site they visit will be near 25°S where a team of Japanese scientists using the ROV Kaiko discovered the Kairei Hydrothermal Field in August 2000. In addition, Expedition #4 will explore for other sites of hydrothermal activity on the Central Indian Ridge.

This expedition has taken over five years to plan and organize. Join the scientists, technicians and crew of the RV Knorr on this historic expedition as they Dive and Discover to explore for hydrothermal vents and animals in the far reaches of the Indian Ocean.

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Objectives
It was less than 25 years ago when oceanographers first discovered hydrothermal vents gushing hot, mineral-rich fluids from the seafloor near the Galapagos Islands.

To their amazement, they found previously unimagined communities of exotic life thriving around these vents. All the materials to support life came from chemicals and minerals in the vents - chemosynthesis. And the energy to support life came not from the sun, but from heat deep within the Earth.

The discovery of hydrothermal vents fundamentally expanded our concepts of “life” on our planet. Since then biologists have found other hydrothermal vent fields, in the Pacific and also in the Atlantic Oceans. They have cataloged more than 500 previously unknown organisms living around these vents.

Curiously, scientists have found that animals and microbes living around Pacific Ocean vents are different from animals living around Atlantic Ocean vents. That got them wondering: What sort of animals live around vents in the ocean in between-the Indian Ocean? Until now, oceanographers haven’t had many opportunities to explore the Indian Ocean seafloor in search of vents and vent life using deep submergence vehicles.

Expedition 4 is the first US research expedition launched to hunt for hydrothermal vents in the Indian Ocean. Vents are usually located on the mid-ocean ridge where tectonic plates move apart and molten rock rises from the mantle to create new seafloor. The scientists will be exploring the Central Indian Ridge in the middle of the Indian Ocean. One site they will visit is the Kairei Hydrothermal Field near 25°S discovered in August 2000 by Japanese scientists.

A team of scientists, specializing in various branches of oceanography, will search for the vents. Biologists will study the life living around them. Geochemists will investigate the chemistry of the life-sustaining fluids spewing out of the seafloor. And geologists will explore the volcanic rocks and terrain of the surrounding seafloor to understand the geological forces that create hydrothermal vents.

What types of animals will we find living around hydrothermal vents on this unexplored mid-ocean ridge? Will they be similar to animals living around vents in the Pacific and Atlantic, or entirely different? How do vent organisms get transported across vast seafloor regions along the global mid-ocean ridge system-which encircles the planet for nearly 60,000 kilometers undersea, and how do they find and settle in different places along the ridge where they can grow? These are the major scientific questions that scientists will try to answer during Expedition 4.

We shall be working at the Central Indian Ridge near 20-25°S latitude where the African and Indian tectonic plates are separating at about 4.5 centimeters (about 1 inch) per year. At the top of the ridge is a deep valley that is about 4-5 kilometers wide. It is inside this valley and along its walls that we will hunt for hydrothermal vents. How shall we find them?

We 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 a smokestack. In the dark depths of the oceans, our instruments can “see” cloudy water and can detect small telltale differences in the temperature of the water.

Once we discover plumes, we will use seafloor mapping systems (DSL-120 sonar and Argo-II) to “look” at the seafloor and try to locate hydrothermal vents. Geologists will look for evidence, including tall structures that might be hydrothermal chimneys sticking up above the seafloor, big cracks (fissures) in the seafloor where hydrothermal fluids might be exiting, and different colored rocks on top of black volcanic lava flows. With Argo-II’s video cameras, we will be able to see black, mineral-rich fluids spewing out of seafloor structures shaped like spires, which we call black smoker chimneys. Or we might see animals, if we are lucky enough to find and pass over a vent.

Once we find the vents, we will send the remotely operated vehicle (ROV) Jason down to them to map the area and sample the vents, microbes and animals. Biologists, chemists and geologists will all want to collect samples to find out what lives at the vents, and to learn about what their living environment is like.

Several types of biologists will be aboard Expedition 4. Ecologists will describe the animals and the ways they interact with each other in the vent communities. Microbiologists will study microbes, which use the harsh chemicals in the vent fluids as sources of energy. These include bacteria and Archaea -- single-celled organisms that are as genetically different from bacteria as bacteria are from trees.

Geneticists will take tissue samples of animals to analyze their DNA and RNA. Comparisons of genetic material will tell them how Indian Ocean vent animals are related to hydrothermal vent fauna elsewhere on the mid-ocean ridge.

Chemists will be studying the chemical composition of the hydrothermal fluids. No vent fluids have been sampled in the Indian Ocean, so chemists are curious to see if Indian Ocean vent fluids are similar or distinctive to those from other parts of the mid-ocean ridge. Different bacteria use different chemicals, so knowing what chemicals are present helps biologists understand why certain animals may be present or absent at the vents.

Much of the geologic data we collect will be analyzed on board to map the vent sites and decide where to sample. The biologists and chemists will be working on the samples as soon as they come on board the ship, and they will also be taking many of the samples back to their labs on shore for more detailed analyses.

Each day will bring new samples, new discoveries and new ideas about how hydrothermal vents in the Indian Ocean fit into the “big picture” of how the Earth works.