News - May 20, 2002
NSF PR 02-36
Dispatch 6, The Straits of Magellan
May 20, 2002 / The Straits of Magellan -- Scientists
on the Nathaniel B. Palmer packed up their
equipment this week as the ship headed north toward
Punta Arenas, Chile. The ship began to rock as she
left the stable ice for open waters, and passengers
worked to restore their sea legs for the dreaded Drake
Passage, the turbulent stretch of water between Antarctica
and South America.
Before they crossed the Drake, however, voyagers had
time for a little fun. The Palmer stopped at
the National Science Foundation's Palmer Station,
where scientists and crew visited elephant seals and
penguins on nearby islands, shopped at the station's
souvenir store, and hiked a nearby glacier. From the
top of the glacier, the constant engine noise of the
Palmer faded, leaving the voyagers in an almost
Today, as the Palmer reentered the Straits of
Magellan -- after a relatively easy crossing through
the Drake -- scientists were glad to be finished with
their work, but also sad to be leaving their home
of the past six weeks.
"I've had a great time and met a lot of interesting
people," reflected Phillip Taisey, a student from
Northeastern University. "I haven't had a single bad
day except for maybe while I was a little seasick
at the beginning of the trip going through the Drake."
"The worst rocking we had was on the way out," agreed
ship's steward Theresa Wisner, who said the trip was
also a success for the cooks. They had the daunting
task of feeding 56 people for six weeks without ever
restocking the larder.
"If you store things right, they last," Wisner said.
"We don't have to think about that when we're home
because the supermarket is right down the street."
Though the kiwis and melons ran out early on, there
were still plenty of oranges, apples and pears because
they were bought unripe and stored in the ship's giant
refrigerator. The lettuce lasted almost the whole
trip; after it went, Wisner served cabbage for salads.
Wisner made the menu up as she went along, based on
what was ripe. "If there was a bunch of celery that
was about to go over, I'd make a stir fry because
it uses lots of celery. I did a pear breakfast when
we had pears that were about to go," she said. Throughout
the trip, passengers noticed that yesterday's meat
often became today's soup, which helped to minimize
Though the scientists enjoyed the meals on board, they
missed food from home. "I can't wait to have a burrito,"
admitted Wendy Kozlowski of Scripps Institution of
Oceanography in La Jolla, Calif.
Kozlowski, along with Kristy Aller of Scripps, has
been mapping the distribution and abundance of the
"primary producers" -- the tiny green phytoplankton
at the bottom of the food chain that make food for
zooplankton and krill.
"I think the trip went really well," said Kozlowski.
"The seas were calmer than during last year's fall
cruise." Kozlowski lost only one sampling cast, out
of 92, due to bad weather.
Kozlowski and Aller filtered water samples along the
Palmer's survey grid, extracting substances
like chlorophyll, the green pigment that absorbs the
sun's energy for photosynthesis. The amount of chlorophyll
in the top layers of water --where the sun can penetrate
-- is one indicator of the mass of phytoplankton in
Kozlowski and Aller also measured phaeophytin, a pigment
produced when krill break down the chlorophyll of
phytoplankton they have eaten. The zooplankton group
saw no obvious increases in krill where Kozlowski
and Aller saw high phaeophytin. But Kozlowski said
the data would need to be analyzed more carefully
to look for links between phytoplankton and the ocean
physics, nutrients, and biology.
"We did get this chlorophyll plot that matches perfectly
with a deep water temperature maximum that John [Klinck]
saw," she said, pointing to a plot showing high levels
of chlorophyll in the north offshore section of the
survey grid. It's possible that deep, warm water intrusions
bring nutrients to the continental shelf and feed
phytoplankton near the surface, she said.
Another success of the cruise was mapping a new piece
of the Southern Ocean floor. The seafloor is rich
with volcanoes, deep troughs, and dents where jagged
icebergs once scraped across the bottom. These features
affect the biology of a region.
For example, SO GLOBEC scientists have slowly been
mapping a deep trough that cuts diagonally across
the continental shelf of the Western Antarctic Peninsula.
Warm water intrusions may enter the continental shelf
through this trough, bringing in nutrients and increasing
the productivity of the strip. Colder, denser water
may also sink deep in the trough, making a habitat
for certain types of fish.
Ping Editing" and "Small Footprints
The Palmer maps the depths of the seafloor with
a "multibeam" sonar system. "It's essentially just
like an echo, when you holler and it bounces back
to you --that's how it works," said Suzanne O'Hara
of Raytheon Polar Services, Co., NSF's logistics contractor
Each of the system's multiple beams sends one "ping"
each second that bounces back from the ocean floor.
"We base our depth on half the time it took the sound
to travel," O'Hara explained.
The beams cover a swath of the ocean floor about three
times the depth of the water. "If you're only in 400
meters of water, you only get a width of about 1200
meters. And that's a very small footprint on the ocean
floor," said O'Hara, who likened it to mowing tiny
strips in a large yard.
"If we had wanted to cover the whole shelf slope area,
it would take years of just driving back and forth,"
SO GLOBEC scientists offset the grid track by about
one-half swath width each research trip and then match
up the overlapping pieces like a puzzle. The mapped
area -- appearing like a boxy maze -- widens with
Each evening, the scientists helped remove artifacts
from the day's data in a chore called "ping editing."
The Palmer was the first NSF Antarctic vessel
to acquire a multibeam system in 1994, and any information
the scientists collect is new, which motivates every
one to help with the task.
Many other scientists -- such as geophysicists, who
hope to understand how glaciers once shaped the Antarctic
seafloor -- will also use this data.
With only a few hours to go before they reached Punta
Arenas -- where the Laurence M. Gould had already
arrived -- voyagers gathered for their last dinner
in the galley. They marveled at their relative luck
with weather and equipment compared to last year's
fall and winter cruises.
An enthusiastic Peter Wiebe, chief scientist aboard
the Palmer, said, "I have only three words:
it went great."