June 07, 2012
J. D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
Maria-Jose Vinas
Goddard Space Flight Center, Greenbelt, Md.
301-614-5883
mj.vinas@nasa.gov
RELEASE: 12-184
NASA DISCOVERS UNPRECEDENTED BLOOMS OF OCEAN PLANT LIFE
WASHINGTON -- Scientists have made a biological discovery in Arctic
Ocean waters as dramatic and unexpected as finding a rainforest in
the middle of a desert. A NASA-sponsored expedition punched through
three-foot thick sea ice to find waters richer in microscopic marine
plants, essential to all sea life, than any other ocean region on
Earth.
The finding reveals a new consequence of the Arctic's warming climate
and provides an important clue to understanding the impacts of a
changing climate and environment on the Arctic Ocean and its ecology.
The discovery was made during a NASA oceanographic expedition in the
summers of 2010 and 2011.
The expedition called ICESCAPE, or Impacts of Climate on EcoSystems
and Chemistry of the Arctic Pacific Environment, explored Arctic
waters in the Beaufort and Chukchi seas along Alaska's western and
northern coasts onboard a U.S. Coast Guard icebreaker. Using optical
technologies, scientists looked at the impacts of environmental
variability and change in the Arctic on the ocean biology, ecology
and biogeochemistry.
"Part of NASA's mission is pioneering scientific discovery, and this
is like finding the Amazon rainforest in the middle of the Mojave
Desert," said Paula Bontempi, NASA's ocean biology and
biogeochemistry program manager in Washington. "We embarked on
ICESCAPE to validate our satellite ocean-observing data in an area of
the Earth that is very difficult to get to," Bontempi said. "We wound
up making a discovery that hopefully will help researchers and
resource managers better understand the Arctic."
The microscopic plants, called phytoplankton, are the base of the
marine food chain. Phytoplankton were thought to grow in the Arctic
Ocean only after sea ice had retreated for the summer. Scientists now
think that the thinning Arctic ice is allowing sunlight to reach the
waters under the sea ice, catalyzing the plant blooms where they had
never been observed. The findings were published today in the journal
Science.
"If someone had asked me before the expedition whether we would see
under-ice blooms, I would have told them it was impossible," said
Kevin Arrigo of Stanford University in Stanford, Calif., leader of
the ICESCAPE mission and lead author of the new study. "This
discovery was a complete surprise."
During the July 2011 Chukchi Sea leg of ICESCAPE, the researchers
observed blooms beneath the ice that extended from the sea-ice edge
to 72 miles into the ice pack. Ocean current data revealed that these
blooms developed under the ice and had not drifted there from open
water, where phytoplankton concentrations can be high.
The phytoplankton were extremely active, doubling in number more than
once a day. Blooms in open waters grow at a much slower rate,
doubling in two to three days. These growth rates are among the
highest ever measured for polar waters. Researchers estimate that
phytoplankton production under the ice in parts of the Arctic could
be up to 10 times higher than in the nearby open ocean.
Fast-growing phytoplankton consume large amounts of carbon dioxide.
The study concludes that scientists will have to reassess the amount
of carbon dioxide entering the Arctic Ocean through biological
activity if the under-ice blooms turn out to be common.
"At this point we don't know whether these rich phytoplankton blooms
have been happening in the Arctic for a long time and we just haven't
observed them before," Arrigo said. "These blooms could become more
widespread in the future, however, if the Arctic sea ice cover
continues to thin."
Previously, researchers thought the Arctic Ocean sea ice blocked most
sunlight needed for phytoplankton growth. But in recent decades
younger and thinner ice has replaced much of the Arctic's older and
thicker ice. This young ice is almost flat and the ponds that form
when snow cover melts in the summer spread much wider than those on
rugged older ice.
These extensive but shallow melt ponds act as windows to the ocean,
letting large amounts of sunlight pass through the ice to reach the
water below, said Donald Perovich, a geophysicist with the U.S. Army
Cold Regions and Engineering Laboratory in Hanover, N.H., who studied
the optical properties of the ice during the ICESCAPE expedition.
"When we looked under the ice, it was like a photographic negative.
Beneath the bare-ice areas that reflect a lot of sunlight, it was
dark. Under the melt ponds, it was very bright," Perovich said. He is
currently visiting professor at Dartmouth College's Thayer School of
Engineering.
The discovery of these previously unknown under-ice blooms also has
implications for the broader Arctic ecosystem, including migratory
species such as whales and birds. Phytoplankton are eaten by small
ocean animals, which are eaten by larger fish and ocean animals. A
change in the timeline of the blooms can cause disruptions for larger
animals that feed either on phytoplankton or on the creatures that
eat these microorganisms. "It could make it harder and harder for
migratory species to time their life cycles to be in the Arctic when
the bloom is at its peak," Arrigo said. "If their food supply is
coming earlier, they might be missing the boat."
Bontempi believes the discovery also may have major implications for
the global carbon cycle and the ocean's energy balance. "The
discovery certainly indicates we need to revise our understanding of
the ecology of the Arctic and the region's role in the Earth system,"
Bontempi said.
For more information and related images, visit:
http://go.nasa.gov/LlgQ76
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