NASA satellite data was used for the first time to
analyze the biology of hot spots along the coast of
Antarctica. The biological oases are open waters, called
polynyas, where blooming plankton support the local food

The research found a strong association between the well being
of Adelie Penguin populations in the Antarctic and the
productivity of plankton in the polynyas. Polynyas are areas
of open water or reduced ice cover, where one might expect sea
ice. They are usually created by strong winds that blow ice
away from the coast leaving open areas, or by gaps appearing
on the ocean’s surface, when flowing ice gets blocked by an
impediment, like an ice shelf.

The Antarctic waters are rich in nutrients. The lack of ice,
combined with shallow coastal waters, provides the top layers
of the ocean with added sunlight, so polynyas offer ideal
conditions for phytoplankton blooms. Because the ice around
polynyas is thin in the early spring when the long Austral day
begins, they are the first areas to get strong sunlight. The
open waters retain more heat, further thinning ice cover and
leading to early, intense, and short-lived plankton blooms.
These blooms feed krill, a tiny, shrimp-like animal, which in
turn are eaten by Adelie Penguins, seabirds, seals, whales,
and other animals.

Although relatively small in area, coastal polynyas play a
disproportionately important role in many physical and
biological processes in Polar Regions. In eastern Antarctica,
more than 90 percent of all Adelie Penguin colonies live next
to coastal polynyas. Polynya productivity explains, to a great
extent, the increase and decrease in penguin population.

“It’s the first time anyone has ever looked comprehensively at
the biology of the polynyas,” said Kevin Arrigo, assistant
professor of Geophysics at Stanford University, Stanford,
Calif. “No one had any idea how tightly coupled the penguin
populations would be to the productivity of these polynyas.
Any changes in production within these polynyas are likely to
lead to dramatic changes in the populations of penguins and
other large organisms,” Arrigo said.

The study, which appeared in a recent issue of the Journal of
Geophysical Research, used satellite-based estimates to look
at interannual changes in polynya locations and sizes;
abundance of microscopic free-floating marine plants called
phytoplankton, which are the base of the polar ocean food
chain; and the rate at which phytoplankton populations thrive.
Covering five annual cycles from 1997 to 2002, 37 coastal
polynya systems were studied.

The largest polynya studied was located in the Ross Sea
(396,500 square kilometers or 153,100 square miles; almost the
size of California). The smallest was located in the West
Lazarev Sea (1,040 square kilometers or 401.5 square miles).
Most polynyas, at their maximum area in February, were less
than 20,000 square kilometers (7,722 square miles).

Data from NASA’s Sea-viewing Wide Field-of-view Sensor
(SeaWiFS) and NOAA’s Advanced Very High Resolution Radiometer
(AVHRR) provided weekly measurements of chlorophyll and
temperature that were used in a computer model to estimate
phytoplankton productivity. The researchers found, taken
together, the Ross Sea, Ronne Ice Shelf, Prydz Bay, and
Amundsen Sea polynyas were responsible for more than 75
percent of total plankton production.

The researchers were surprised to find how closely connected
the Adelie Penguins were to the productivity of their local
polynyas. The more productive polynyas supported larger
penguin populations. The more abundant krill fed more
penguins, and the birds had shorter distances to go to forage,
which reduced exposure to predators and other dangers.

The NASA Oceanography Program, the National Science
Foundation, and the U.S. Department of Energy funded this
research. NASA’s Earth Science Enterprise is dedicated to
understanding the Earth as an integrated system and applying
Earth System Science to improve prediction of climate,
weather, and natural hazards using the unique vantage point of

For information about the research and images on the Internet,

For information about Adelie Penguins, on the Internet, visit: