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Although it covers more than two-thirds of Earth's surface,
much of the deep sea remains unknown and unexplored, and many
questions remain about how its environment changes over time.
A new study led by scientists at Scripps Institution of Oceanography
at the University of California, San Diego, has shed new light
on significant changes in the deep sea over a 14-year period.
Scripps Institution's Henry Ruhl and Ken Smith show in the
new issue of the journal Science that changes in climate at
the surface of the ocean may be impacting communities of larger
animals more than 13,400 feet below the ocean surface.
Important climatic changes such as El Niño and La Niña
events are well known to affect regional and local areas,
but Ruhl and Smith describe how such changes also can extend
to the deep ocean, one of Earth's most remote environments.
"Large animals, the kind you would be able to see if
you were standing on the bottom of the ocean, may be impacted
by climate just the same as animals in shallow water or terrestrial
environments," said Ruhl.
In 1999, Smith and colleague Ronald Kaufmann showed that
seafloor-dwelling animals were experiencing a long-term food
shortage. The new study indicates that food supplies have
since increased and that climate, food supplies and the abundance
of large animals on the seafloor are linked. Since 1989 members
of Smith's laboratory team have studied a deep-sea location
in the eastern North Pacific Ocean approximately 136 miles
west of Point Conception off the central California coast.
"Station M," as the location is known, has been
the site of one of the longest time-series studies of any
abyssal area in the world.
"It's important to study these places on a long timescale
because you can't predict what is going to happen by just
studying it once," said Smith, a research biologist in
the Marine Biology Research Division at Scripps. "If
you have changes such as these in such a large portion of
the globe, you've got to pay attention to it." Ruhl and
Smith use time-lapse photography, sediment traps and a host
of other equipment to capture basic ecological information
related to the seafloor community. The Science paper illustrates
a stark contrast in the community structure of the 10 most
dominant mobile animals before and after the powerful 1997-1998
El Niño/ La Niña event. Animals examined as
part of the study include deep-ocean sea cucumbers, urchins
and brittle stars. While numbers of some animals decreased
when food supplies were low during the 14-year period, certain
other species seemed to thrive on such conditions. For a number
of possible reasons, some of these animals may have a competitive
advantage during food shortages.
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Scientists prepare to launch a "sled" used
for capturing images of the deep sea environment. The
sled takes nearly two-and- a-half hours to reach it's
destination more than 13,000 feet deep.
Credit: Scripps |
During their many trips to Station M, the researchers worked
aboard the Scripps research vessel New Horizon. Each expedition
began with a 30-hour trip out of San Diego heading northwest
covering 300 miles. The researchers typically remained at
Station M for a week or more to complete the various tasks
necessary to retrieve, maintain and deploy instrumentation.
One of the key pieces of equipment they used is a camera mounted
on a "sled" that moves across the ocean bottom.
Once lowered overboard, the device takes nearly two-and-a-half
hours to reach its more than 13,000-foot-deep destination.
A small animal-collecting net also makes the trip so the scientists
can retrieve and inspect the various animals seen in the photography.
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An image of the animal Psychropotes
longicauda on the seafloor at Staion M.
Credit: Scribbs |
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The camera records about one photograph every five seconds.
One hour of images can lead to weeks of analysis for the scientists.
Forty-eight such photo transects (one transect can be nearly
one mile across) were analyzed as part of the study.
"The ocean is a source of food for human populations,
but it's also a place of waste disposal," said Smith.
"It's important to consider how you impact the deep sea.
In that view it's puzzling that we don't study the deep sea
in more detail."
Funding for the study was provided by the National Science
Foundation.
Scripps Institution of Oceanography, at the University of
California, San Diego, is one of the oldest, largest, and
most important centres for global science research and graduate
training in the world. The National Research Council has ranked
Scripps first in faculty quality among oceanography programs
nationwide. The scientific scope of the institution has grown
since its founding in 1903 to include biological, physical,
chemical, geological, geophysical, and atmospheric studies
of the earth as a system. Hundreds of research programs covering
a wide range of scientific areas are under way today in 65
countries. The institution has a staff of about 1,300, and
annual expenditures of approximately $140 million from federal,
state, and private sources. Scripps operates one of the largest
U.S. academic fleets with four oceanographic research ships
and one research platform for worldwide exploration.
For further information contact Mario Aguilera or Cindy Clark
scrippsnews@ucsd.edu
or visit www.scripps.ucsd.edu
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