Mission & Objectives
Scientists & Crew
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a bathymetric map of the study area.
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Collecting Deep-Sea Corals
Dive and Discovers 2003 expedition will
journey to the New England Seamounts,
a chain of extinct, undersea volcanoes about 500 miles off the east
coast of North America.
The scientific treasures the expedition seeks are deep-sea corals,
whose skeletons may reveal how Earths climate rapidly cooled or warmed
in the past. Learning how and why Earths climate shifted
in the past gives us an idea of how it might change in the future.
Scientists think that abrupt climate changes may
have been caused by changes in the circulation of the deep ocean.
In particular, they think that a cold, salty, deep water
mass in the North Atlantic stopped flowing and then started flowing
again several times in the past. Each time this flow has shut
down or turned on, Earths climate has
The New England Seamounts rise thousands of meters
up from the seafloor, right into the pathway of this deep, cold
water mass. On the seamounts grow large populations of deep-sea
corals. Throughout their lives, coral skeletons absorb chemicals
from the waters they are growing in. By analyzing the coral skeletons,
scientists can determine how old the corals are and whether the
cold, deep water was flowing when they lived. By sampling live
and fossil corals from the top to the bottom of the seamounts,
they hope to find out how and when this deep water mass grew larger
or smaller, became warmer or colder, and flowed higher or lower
in the depths-as far back as 70,000 years ago.
Expedition 7 travels to the New England Seamounts,
a chain of extinct, undersea volcanoes about 500 miles off the
east coast of North America. On the seamounts themselves grow one
of the chief targets of the cruise: deep-sea corals. These are
similar to corals found in shallow, tropical waters but they dont
have symbiotic algae that require
light. Instead, they rely on capturing food from the water column.
Therefore, they can grow in the darkest depths of the ocean.
The corals skeletons can provide crucial
clues to the history of Earths climate,
which is what the cruise is all about. We hope to find out how and
why the planets climate has rapidly shifted from cold to warm
periods, and to use that information to predict how it might change
in the future.
The corals skeletons are rich repositories of environmental information.
The biochemical composition of their skeletons is different if they grow in different
water conditions. And water conditions change as Earths climate does.
Like undersea tape recorders, individual corals at different depths in the ocean
have recorded how Earths climate has changed through time. But getting
those corals back to the lab is not the only goal of the expedition.
Our broader aim is to use the New England Seamounts as a test case: What we learn
about retrieving and studying corals here will show us the best ways of getting
other corals in the future, from the deep Pacific Ocean to the waters off Antarctica.
The first day the vessel Atlantis arrives at a particular seamount, it
will go back and forth over an area with sonar equipment
to create detailed topographic maps of the sea floor below. We call this mowing
the lawn! Each map will contain all sorts of seafloor features such as
cliffs, flat areas, bowls, ridges, spires, and plains. With these maps in hand,
we will climb into the deep-diving submersible Alvin and descend to explore
the most scientifically promising underwater features.
Both Alvin and the unmanned vehicle ABE, the Autonomous
Benthic Explorer, will collect overlapping photos of the seafloor
that we will combine to make photomosaics. We will also generate
additional maps that are focused on smaller areas but with much more
detail. By putting these maps together with the large-scale maps
made by Atlantis, we will come up with some general guidelines
that scientists can use to find information-rich corals anywhere.
In the future, we hope that scientists will look at topographic maps
of the sea floor and be able to determine the likeliest places to
Alvin will be doing the heavy lifting -- of both living
and fossil corals. The principal coral we expect to find is Desmophyllum
cristagali, which grows roughly one millimeter per year
for several decades, or sometimes up to 150 years. Other corals
on the seamounts are Enallopsamia rostrata and Lophelia
Once aboard, the corals will be documented, photographed,
cleaned (the dead ones) and tissue-sampled (the living ones) for
genetic and reproductive analysis to yield a sort of detailed family
tree. While all the physical evidence is being processed, digital
data will be assembled: maps, photo and video documentation, and
information about local environmental conditions such as temperature,
salinity, and current speed. This database of coral habitats in different
climates is another important goal of the cruise.
The full scientific value of the corals will become apparent only partially during
Expedition 7. Atlantis has laboratory facilities that will allow scientists
to study the treasures theyve retrieved, but many of the most perplexing
problems will take months or more to solve, after the corals have been brought
back to more sophisticated labs on shore. There, theyll undergo more sophisticated uranium-series and radiocarbon
dating and chemical analysis. With this new chemical information in hand,
we will be able to plumb deeper into the mysteries of climate change.
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