News - May 2002
NSF PR 02-36
Dispatch 2, from the Second Data-gathering Cruise
of SO GLOBEC
April 15, 2002 / Off the coast of Adelaide Island,
Antarctica: Science has begun in earnest aboard
the R.V. Nathaniel B. Palmer. But just a few
days ago, the Palmer's seven laboratories were empty.
As winds reached up to 60 nautical miles per hour (69
mph) through the Drake Passage -- a notoriously unpredictable
and often violent body of water -- scientists experienced
firsthand how life in the ocean depends on the movements
of the sea.
"I'm glad I wasn't throwing up, that's for sure," said
researcher Kristy Aller of the Scripps Institution
of Oceanography in La Jolla, Calif. "But I didn't
feel so hot. I guess none of us did really."
Ship's mate John Higdon, who has been crossing the
Drake for three years aboard the Palmer, rated the
passage 7 out of 10 for roughness. He estimated the
waves climbed to 6 or 7 meters (20-25 feet) for a
time. Though the 93-meter (308-foot) Palmer
rides lesser swells with ease, this height was enough
to tip chairs and knock keyboards to the floor in
the ship's computer lab.
Cycling between weightlessness and descent, the sensation
was much like being on an endless roller coaster.
Once nausea hit, time seemed to pass very slowly.
The mess hall was deserted but for the ship's hardy
"I never really worry about getting seasick, only about
getting sick of the seas," Higdon said. "If I had
gotten seasick, I would have become a doctor," he
Then, just as quickly as the seas had stirred, the
lurching motion subsided. The treachery of the Drake
was forgotten as research took on a frenzied, 24-hour-a-day
pace. The Palmer began its mission to map the
structure and biology of the Southern Ocean along
a 92-point, ladder-shaped grid off the Western Antarctic
Water in the ocean, far from being uniform, is organized
into separate units, or masses, that have distinct
features and histories. Differences in density and
salt content prevent these water masses from readily
mixing and maintain environments that may be as disparate
as a rainforest and a desert.
"You'd be amazed how much structure there is," said
Julian Ashford of Old Dominion University who is working
with the Palmer's Conductivity, Temperature, Depth
(CTD) group, charting the basic physical features
of the sea. The CTD group will create maps that show
high and low zones of salt, oxygen, and temperature;
much like elevation maps show mountains and valleys.
Biologists aboard the Palmer will relate their
observations of marine life to the findings of the
CTD group. "What makes this cruise special is that
we have a whole bunch of biologists focusing their
work around the physical structure of the ocean,"
Just like the topography of land governs its ability
to support life, so too does the layout of the ocean.
For example, the Antarctic Circumpolar Current (ACC),
which circles the continent, governs much of the life
in the Antarctic. The current forms a swift-moving
corridor in which animals can travel for thousands
of miles. "They don't even know they are moving because
their environment never changes," Ashford said. The
current may also bring warmer, nutrient-rich oceanic
water to the continental shelf of Antarctica, potentially
affecting the biology there.
"Water movements affect where the food chain starts,
where the green stuff is, where the krill is that
eats the green stuff, and so on," said Andres Sepulveda,
a graduate student from Old Dominion University who
is also working with the CTD group.
Working in the "Baltic Room"
The CTD group will measure the physical properties
of the water column and collect water samples at each
of the 92 points, or stations, on the grid. Other
instruments will measure currents, weather, and ocean
depth as the ship travels the 8 kilometers to 40 kilometers
(five to 25 miles) from station to station.
The CTD consists of a six-foot-high, three-foot-wide
cylindrical frame holding instruments and submarine-shaped
collection bottles arranged in a circle. At each station,
CTD scientists and marine technicians lower the CTD
into the sea via a cable and sheave that extends and
retracts on an extensible arm from the ship's "Baltic
room." The CTD takes measurements eight times a second
and relays these to a computer in real time, via electrical
wires in the cable.
When the Baltic room's two-story high door opens to
deploy the CTD, it is like opening a door to another
world. Deep blue water stirs against a paler, but
still intense, blue sky. White-with-black Cape Petrel
birds glide just above the water's surface, appearing
illuminated beside the blue. Fresh, cold air, often
mixed with snow flurries, drifts through the door.
Between the first few stations, marine technicians
Alice Doyle and Jennifer White climbed the CTD's frame,
as if it were a jungle gym, wielding their screwdrivers
to tackle leaking bottles and other kinks in the system.
At the third station, engineer Chris MacKay added a
"microstructure profiler," resembling a rocket, to
the CTD. This device measures salt and temperature
like the CTD, but takes 512 samples per second instead
of eight, thus tracking finer variations in water
To illustrate the device's function, consider what
it could reveal about a simple cup of coffee. MacKay
recounted this analogy from a colleague: "He said
that if you took the coffee, poured in some cream,
stirred it and then profiled through it, you could
tell the original temperatures of the coffee and the
cream, how much energy was put into the system when
you stirred it, how long it would take to totally
mix, and when it would stop moving."
Each time the CTD is reeled back into the Baltic room,
scientists with test tubes and bottles swarm the machine
like vultures, ready to grab their water samples.
First in line are chemists like graduate student Rob
Masserini of the University of South Florida, who
will examine the nutrient contents of the water layers.
"These nutrients are essentially fertilizer that phytoplankton
use to grow. They support the base of the food chain,"
Masserini is particularly interested in ammonia, a
form of nitrogen that phytoplankton readily take up
to make proteins. Last year's SO GLOBEC cruises revealed
startlingly high levels of ammonia and unexplained
seasonal shifts in concentrations along the Western
As to why that is the case, Masserini said, "we have
no answers only questions."
The first days of data collection were a jumble of
equipment tweaks and test runs, not only for the CTD
group, but also for scientists studying plants and
animals from algae to whales. Lead CTD scientist John
Klinck of Old Dominion University said things would
calm down soon, however.
"In a few days, this will be as coordinated as a fine
ballet," he said.