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Big
waves on the high seas. Click image for larger
view.
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| | SeaBeam Mapping
on the High Seas
September 13,
2001
Diana Payne
The Maritime
Aquarium at Norwalk/
Connecticut Sea Grant
Karl Stanford,
Teacher
Lincoln Academy, Newcastle, Maine
"Attention
all hands, attention all hands. We will be making a turn. Prepare
for rolling motion."
--Any crew member at the helm of the R/V
Atlantis during the last three days
Once again, the
Alvin dive was cancelled. The science party has sat by this
week and watched dive after dive fade. Still, few sat idle. Digital
video and still pictures were edited and enhanced electronically.
Some try to catch a nap, making up sleep lost due to the constant
tossing of the R/V Atlantis in the early morning hours. Each
task was complicated by the nearly constant rolling and pitching of
the ship. The ship's intercom toned, "Attention all hands, attention
all hands. We will be making a turn. Prepare for rolling motion."
The warning was welcome, although some of us asked, "So, this will
be a change?" Through most of the day, we plowed through
white-capped swells as the ship's SeaBeam® multibeam sonar system
pinged the depths below. Although
Alvin was unable to dive today, the other high-tech tools
aboard the Atlantis didn't go unused. The topography of the
marine seamounts was analyzed using the latest in acoustic
technology. A bathymetric chart of the area shows isobaths (similar
to contour lines on a topographic map) ringing each of the
seamounts. Two of the seamounts, Bear and Physalia, were planned
dive locations on this leg of Deep East, but both dives were
cancelled.
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SeaBeam 3-D
visualization of Bear Seamount. Click image for larger
view.
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| | The problem with current bathymetric charts is that they give
only a crude shape of the undersea canyons and plateaus,
particularly this far offshore. The SeaBeam system worked through
the day, raining sound waves down onto the sea floor like the spray
pattern on an aerosol paint can. The frequent course changes were
necessary for SeaBeam to do its job properly. When an area is mapped
using the SeaBeam system, the ship has to steam down a series of
parallel lanes. Each lane "paints" another swath of data points into
the computer. The decision regarding lane spacing depends on the
depth of the water.
SeaBeam's task is not an easy one.
For any map to be useful, it must be referenced to a datum -- an
objective benchmark. Both topographic and bathymetric maps are
customarily referenced to mean sea level (the midpoint between high
and low tide). If the Atlantic was a flat pond or puddle, this
reference point would be simple. As the Atlantis steams its
lanes, however, it heaves up and down as much as 5 m. The ship rolls
up to 14 degrees from port to starboard, and it pitches up to 10
degrees through the swells. Through all of this, the SeaBeam sends
141 sound beams into the water every 8 seconds as Atlantis
travels at about 8-9 knots. The system uses the return time for each
echo to calculate the distance from the ship's hull to each of the
141 points on the ocean floor.
If this sounds like a mathematical
nightmare, it should! To add one more complication, the system must
record and plot the location of the ship on the sea surface, too.
This is accomplished using the GPS (global positioning system), a
system of satellites that can locate any position on land, sea, or
water to within a few meters.
The products of the SeaBeam system
and the amount of data it collects are impressive. Just a few
minutes of SeaBeam sampling provides more data than were used to
produce the original NOAA depth charts for this entire area. The
system "stitches together" the data collected from each lane of
sampling and renders a color-keyed, three-dimensional map of the
ocean floor. Information on the map is critical to the pilot and
crew of the Alvin submersible as well as to the scientists
aboard the R/V Atlantis. Dive locations are not selected
randomly; they are based on the shape and slope of features on the
ocean floor. Data collected by the SeaBeam system will also be made
available to the public for research purposes.
Alvin
sat quietly in its hangar today, but thanks to the SeaBeam system,
science has millions of new data points -- important tools in the
continuing exploration of Deep East.
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Captain
William Hugo Amaru |
| | Interview with
Captain William Hugo Amaru
Commercial Fisherman, Owner/Captain, F/V Joanne
All
Ocean
Explorer Team: What is your purpose on
the Deep East Expedition?
Capt. Amaru: Dr. Peter Auster invited me to participate as a member of
the Deep East team to act as an information conduit for the team
about sea-floor issues from the perspective of a commercial
fisherman. I was also hoping to become better informed about the
techniques that a 21st-century scientific expedition of discovery
would employ.
Ocean Explorer Team: What is
your perspective as a commercial fisherman on this
expedition?
Capt. Amaru: Well, you have to
understand that within the commercial fishing industry, some
fishermen have been challenged by scientists for the destruction of
habitats. There is a question within the fishing community
concerning the evidence of said destruction. Most fishers are aware
of the concern over damaging ocean habitats, and we are not ignorant
to the situation. Moreover, we want to improve our technology to
lessen any actual impacts on sea-floor communities and their
environment. Another important focus, at present, is to create a
relationship that develops a bond between the science and fishing
communities. Many fishermen think like scientists, and want to work
with scientists on some common goals, such as long-term
sustainability. The science community often overlooks the fact that
the commercial-fishing public has a great deal of information to
share. It could be more productive to pool that knowledge and work
to improve our perceptions of each other. As an example, the Sea
Grant Program in New England has successfully joined science and
fishing for positive results that came from very different
sources.
We believe that science can benefit from the fishing
industry's collective knowledge of the marine environment with an
emphasis on cooperative research. Together, we can investigate how
various habitats are being affected by bottom fishing. Fishermen can
also help collect specific information on animal species, and
collaborate with stock assessments for both the science and fishing
communities. We are already working to see this become a reality,
but we need to do more.
Another issue is that we need to
better define our terms. The term "clear-cutting," for example, is a
harsh accusation for the fishing community to bear. We do not want
to damage an entire ecosystem, as the term implies. Fishermen tend
to go back to the same fishing areas year after year. If we were, in
fact, doing the kind of damage that the term implies, we would have
been ashore with no fish to catch long ago. Not all that we do in
taking from the oceans harms the environment, and not all fishing is
done the same way. The fishing industry is trying to change in ways
that are positive, and we want to provide for the greatest benefit
while lessening the impact on the environment. Distorted information
provided out of context has a negative impact on fishing people and
their families. Fishermen are proud and very independent people. We
need to take a look at the techniques for catching certain types of
fish and improve in that area, but we will do a better job if we
find common ground and promote mutual respect for each other in
doing so.
Ocean Exploration
Team: What type of personal background do
you have to be the captain of a commercial fishing
boat?
Capt.
Amaru: I was born in Rhode Island and have
always been a coastal dweller. I graduated from the State University
of New York at Albany with a bachelor of arts in musical
performance. From there, I played with the Albany Symphony on
clarinet. After moving back to Cape Cod, I worked on the side cod
jigging, as I had done to get through college. As a child, I always
loved to fish, and I did quite often. It got to a point where I
needed to make a career choice. I purchased my first commercial
boat, a 30-ft Maine- built lobster boat, in 1974, and began a new
full-time career. To this day, I still have a strong feeling for my
music and enjoy it every day.
Ocean Exploration Team: How
does your commercial fishing vessel differ from the R/V
Atlantis?
Capt.
Amaru: No comparison. The vessels are as
different as night and day. The only things they have in common are
a diesel engine and a crew. Each ship has its own marine function.
The R/V Atlantis is the most modern and comfortable research
vessel on the East Coast. It is designed for data collecting around
the world and is funded by research or educational organizations and
the U.S. Government. My commercial fishing vessel is designed to
catch fish and to provide income to my crew and myself. It is a
small, basic boat of 50 ft that I lavish tons of attention and love
on, and it loves us back.
Ocean Exploration
Team: How does this expedition relate to
commercial fishing?
Capt. Amaru: This is a most
relevant question. I believe that good science developed by a
broad-based science approach produces the best tools for the
development of sustainable and renewable fisheries. Combining the
scientific and practical backgrounds of divergent groups, as Deep
East does, sets an example for how best to develop and harvest
renewable marine resources.
Interview by Caren A.D. Menard of the Ocean Explorer
Team.
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Dr. Ivar
Babb
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| | Interview with
Ivar G. Babb
Director, National Undersea Research Center for the North Atlantic and
the Great Lakes
Ocean Explorer
Team: What type of technology is used to
evaluate a study site?
Dr. Babb: We use several technologies to assess a site
prior to diving. Initially, we brought NOAA bathymetric (depth) data
into a geographic information system (GIS). These data, together
with historical dive data and towed camera systems, were used to
select the initial dive sites. We then selected the boundaries of an
area to be surveyed using a multibeam sonar system. This system
provides a landscape view of the ocean floor using, as the name
implies, multiple sonar beams to cover a wide swath of the ocean
floor. We can then use the shipboard computers to generate a 3-D map
that provides a good view of the topography of the sea floor. All of
the research being conducted on this leg will make good use of this
capability. For example, knowing the relationship of coral
communities to the landscape features gives us clues to their
ecological role, recruitment, and reproduction. The genetic work
being done on the corals will also rely upon these maps to better
understand the spatial relationships of populations that may or may
not be from the same gene pool. The depth is also a major
determinant of fish distributions.
Ocean Explorer Team: What are
the outreach applications for this type of technology (GIS and
multibeam)?
Dr. Babb: These technologies allow us
to visualize the sea floor with a satellite view. The map provides
the baseline upon which we can add layers, including population data
and genetic information. Most people view the ocean as a vast, flat
blue plane. These maps show the extension of the land and its
complexities beneath that featureless plane, and gives a more
complete three-dimensional picture of the oceans. These maps,
combined with outstanding video and photographic imagery, provides
the public with a new perspective on the ocean's beauty and
complexity. It is hoped that this will raise public awareness of the
deep sea and help generate greater stewardship and conservation of
the oceans. These maps also have an immense commercial application
in terms of precisely mapping sea-floor resources.
Ocean Explorer
Team: How can the imagery and maps be
utilized?
Dr. Babb: We hope to develop virtual
tours of the sea floor combining all of the data layers and imagery.
These would be implemented on interactive Web sites and distributed
on CD-ROMs or DVDs. Researchers will directly use the maps in
reports, presentations, and publications. They also provide
scientists with a tool to measure changes over time and
space.
Ocean Explorer Team: What type
of educational degree do you have for the job that you
do?
Dr.
Babb: I hold a master of science in marine
botany from the University of Maine, specializing in the study of
seaweeds. I also have a master of marine affairs from the University
of Rhode Island.
Ocean Exploration
Team: Personally, what do you hope to
gain from your experience with the Deep East
Expedition?
Dr. Babb: Many facets of this
expedition will remain with me for a long time. Clearly, I will
remember and apply the new discoveries we are making of the deep-sea
canyons and seamounts. If Hurricane Erin permits me the opportunity
to dive in the Alvin, I will learn more about the
submersible's capabilities and limitations. I have dived in several
other submersibles and have a good understanding of what they can
do, but this will give me a better idea of what Alvin can do.
Secondly, I am gaining a great deal of personal satisfaction dealing
with the scientists, technicians, educators, teachers, writers, and
artists on this cruise. The group is truly diverse, with each person
having a fascinating background and personal history. There are also
an amazing comaraderie and chemistry on board as we deal with the
horrific news from New York City, Washington, DC, and Pennsylvania,
both individually and collectively. Finally, we are truly exploring
new areas of the ocean. The thrill of discovery as one dives, using
scuba, remotely operated vehicles, or submersibles, never grows old.
Speaking from experience is always the loudest voice.
Interview by Caren A.D. Menard
of the Ocean Explorer Team.
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