[Vision2020] Woods Hole Oceanographic Institution: 6-20-2012: Melting Sea Ice Threatens Emperor Penguins

[Ted Moffett]

Melting sea ice threatens emperor penguins, study finds (w/ Video)

June 20, 2012 <http://phys.org/archive/20-06-2012/>
http://phys.org/news/2012-06-sea-ice-threatens-emperor-penguins.html
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http://www.whoi.edu/page.do?pid=50242&tid=3622&cid=141592Melting Sea Ice
Threatens Emperor Penguins, Study Finds

*FOR IMMEDIATE RELEASE*

Media Relations Office

media at whoi.edu

June 20, 2012

(508) 289-3340

At nearly four feet tall, the Emperor penguin is Antarctica’s largest sea
bird—and thanks to films like “March of the Penguins” and “Happy Feet,”
it’s also one of the continent’s most iconic. If global temperatures
continue to rise, however, the Emperor penguins in* *Terre Adélie, in East
Antarctica* *may eventually disappear, according to a new study by led by
researchers from the Woods Hole Oceanographic Institution (WHOI). The study
was published in the June 20th edition of the journal *Global Change
Biology.*

“Over the last century, we have already observed the disappearance of the
Dion Islets penguin colony, close to the West Antarctic Peninsula,” says
Stephanie Jenouvrier, WHOI biologist and lead author of the new study.  “In
1948 and the 1970s, scientists recorded more than 150 breeding pairs there.
By 1999, the population was down to just 20 pairs, and in 2009, it had
vanished entirely.” Like in Terre Adélie, Jenouvrier thinks the decline of
those penguins might be connected to a simultaneous decline in Antarctic
sea ice due to warming temperatures in the region.

Unlike other sea birds, Emperor penguins breed and raise their young almost
exclusively on sea ice. If that ice breaks up and disappears early in the
breeding season, massive breeding failure may occur, says Jenouvrier. “As
it is, there's a huge mortality rate just at the breeding stages, because
only 50 percent of chicks survive to the end of the breeding season, and
then only half of those fledglings survive until the next year,” she says.

Disappearing sea ice may also affect the penguins’ food source. The birds
feed primarily on fish, squid, and krill, a shrimplike animal, which in
turn feeds on zooplankton and phytoplankton, tiny organisms that grow on
the underside of the ice. If the ice goes, Jenouvrier says, so too will the
plankton, causing a ripple effect through the food web that may starve the
various species that penguins rely on as prey.

To project how penguin populations may fare in the future, Jenouvrier’s
team used data from several different sources, including climate models,
sea ice forecasts, and a demographic model that Jenouvrier created of the
Emperor penguin population at Terre Adélie, a coastal region of Antarctica
where French scientists have conducted penguin observations for more than
50 years.

Combining this type of long-term population data with information on
climate was key to the study, says Hal Caswell, a WHOI senior mathematical
biologist and collaborator on the paper.

“If you want to study the effects of climate on a particular species, there
are three pieces that you have to put together,” he says. “The first is a
description of the entire life cycle of the organism, and how individuals
move through that life cycle. The second piece is how the cycle is affected
by climate variables. And the crucial third piece is a prediction of what
those variables may look like in the future, which involves collaboration
with climate scientists.”

Marika Holland of the National Center for Atmospheric Research is one such
scientist. She specializes in studying the relationship between sea ice and
global climate, and helped the team identify climate models for use in the
study.

Working with Julienne Stroeve, another sea ice specialist from the National
Snow and Ice Data Center, Holland ultimately recommended five distinct
models. “We picked the models based on how well they calculated the sea ice
cover for the 20th century,” she says. “If a model predicted an outcome
that matched what was actually observed, we felt it was likely that its
projections of sea ice change in the future could be trusted.”

Jenouvrier used the output from these various climate models to determine
how changes in temperature and sea ice might affect the Emperor penguin
population at Terre Adélie. She found that if greenhouse gas emissions
continue to rise at levels similar to today—causing temperatures to rise
and Antarctic sea ice to shrink—penguin population numbers will diminish
slowly until about 2040, after which they would decline at a much steeper
rate as sea ice coverage drops below a usable threshold.

“Our best projections show roughly 500 to 600 breeding pairs remaining by
the year 2100. Today, the population size is around 3000 breeding pairs,”
says Jenouvrier.

The effect of rising temperature in the Antarctic isn’t just a penguin
problem, according to Caswell. As sea ice coverage continues to shrink, the
resulting changes in the Antarctic marine environment will affect other
species, and may affect humans as well.

**“We rely on the functioning of those ecosystems. We eat fish that come
from the Antarctic. We rely on nutrient cycles that involve species in the
oceans all over the world,” he says. “Understanding the effects of climate
change on predators at the top of marine food chains—like Emperor
penguins—is in our best interest, because it helps us understand ecosystems
that provide important services to us."

Also collaborating on the study were Christophe Barbraud and Henri
Weimerskirch of the Centre d'Etudes Biologiques de Chizé, in France, and
Mark Serreze of the National Snow and Ice Data Center in the United States.

Funding for the study was provided by the WHOI Ocean Life Institute, Arctic
Research Initiative, and Access to the Sea, the National Science
Foundation, REMIGE (Behavioral and demographic REsponses of Indian ocean
Marine top predators to Global Environmental changes) program, Agence
National de la Recherche Biodiversité, Zone Atelier de Receherches sur
l’Environment Antarctique et Subantarctique, the Institut Paul Emilie
Victor (IPEV), Alexander von Humboldt Foundation, Marie-Curie European
fellowship, and the Cooperative Institute for Research in Environmental
Sciences visiting fellowship.

*The Woods Hole Oceanographic Institution is a private, non-profit
organization on Cape Cod, Mass., dedicated to marine research, engineering,
and higher education. Established in 1930 on a recommendation from the
National Academy of Sciences, its primary mission is to understand the
oceans and their interaction with the Earth as a whole, and to communicate
a basic understanding of the oceans’ role in the changing global
environment. For more information, please visit www.whoi.edu.*

Originally published: June 20, 2012

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