Dive and Discover’s first expedition of 2001
will be a 40 day long voyage to explore for hydrothermal vents at the mid-ocean
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
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
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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It was less than 25 years ago when oceanographers first discovered hydrothermal
vents gushing hot, mineral-rich fluids from the seafloor near the Galapagos
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.