Andrea Thompson, livescience.com Yahoo News 12 Mar 09;
Rapid climate changes along the Antarctic Peninsula have caused a simultaneous shift in the biological productivity of the area, finds a new study that could explain why some penguins and other species there are on the decline.
The western portion of the Antarctic Peninsula (the northernmost part of the continent) has experienced 4.5 degrees Fahrenheit (2.5 degrees Celsius) of warming over about the last 30 years - more than anywhere else on the planet - and declining sea ice coverage.
This warming caused a shift from the usual cold, dry climate of the area to warmer, wetter conditions, at least in the northern parts of the peninsula, in the past few decades.
Along with this regional climate change , researchers have noticed that populations of Adelie penguins and krill - both of which thrive in a cold, dry climate - have moved southward (poleward). Meanwhile other species, particularly Chinstrap penguins, are taking over the northern areas.
Martin Montes-Hugo of Rutgers University in New Jersey, along with his colleagues, suspected that the migration of the penguins could be related to changes at the base of the Antarctic food chain, namely phytoplankton.
Using data from 30 years of satellite coverage and field studies, they determined that levels of phytoplankton off the western shelf of the peninsula have declined by 12 percent over that time.
"We're showing for the first time that there is an ongoing change on phytoplankton concentration and composition along the western shelf of the Antarctic Peninsula that is associated with a long-term climate modification," Montes-Hugo said. "These phytoplankton changes may explain in part the observed decline of some penguin populations."
The results of the study, funded in part by the National Science Foundation, are detailed in the March 13 issue of the journal Science.
"Now we know that climate changes are impacting at the base of the food web and forcing their effects on up through the food chain," said study team member Hugh Ducklow of the Marine Biological Laboratory in Woods Hole, Mass.
Climate change effects seen in Antarctic winds
Yahoo News 12 Mar 09;
WASHINGTON – Changing wind patterns linked to global warming are altering the food chain in Antarctica and may lead to further increases in greenhouse gases in the atmosphere.
The most basic food, plankton, is declining in the northern portions of the Antarctic peninsula reaching toward South America, researchers report in Friday's edition of the journal Science.
At the same time, populations of Adelie penguins, who require a colder climate, have dropped sharply in that region, while warmer-weather chin-strap penguins have increased.
"We're showing for the first time that there is an ongoing change on phytoplankton concentration and composition along the western shelf of the Antarctic Peninsula that is associated with a long-term climate modification. These phytoplankton changes may explain in part the observed decline of some penguin populations," Martin Montes-Hugo, a marine scientist at Rutgers University, said in a statement.
The change reflects shifting patterns of cloud cover, ice formation and winds, the report said.
A separate report in the same edition of Science raises the possibility that new wind patterns could result in more upwelling of deep water in the region, which would then release stored carbon dioxide, potentially increasing global warming.
"The faster the ocean turns over, the more deep water rises to the surface to release CO2," said Robert Anderson, a geochemist at Columbia University's Lamont-Doherty Earth Observatory. "It's this rate of overturning that regulates CO2 in the atmosphere."
"Mad" Microplants Show Antarctic Climate Change
Deborah Zabarenko, PlanetArk 13 Mar 09;
WASHINGTON - You just don't want to make phytoplankton mad.
These microscopic sea plants are at the bottom of the food chain in the waters that surround the Antarctic peninsula, and when they're unhappy, everything that depends on them suffers, including fish, penguins and possibly, eventually, people.
A new study published on Thursday in the journal Science indicates that some of these Antarctic phytoplankton have become increasingly grumpy over the last 30 years.
Like most plants, phytoplankton need food and sunlight to survive. For some that live off the west coast of the Antarctic peninsula, getting these essentials has been an increasing challenge, with a 12 percent decrease in phytoplankton populations seen in the last three decades.
U.S. researchers figured this out by looking at satellite data and tracking the amount of chlorophyll -- a sign of phytoplankton photosynthesis -- in the Southern Ocean off the Antarctic peninsula, a long tail of land that juts out from the main body of the continent and points toward South America.
This area is a good place to look for signs of climate change, because it is warming faster than any other place on Earth in the winter.
Phytoplankton are excellent markers for climate change because they respond quickly, sometimes in as little as a day, to varying environmental conditions, and because so much of the food chain relies on their survival.
SUNLIGHT MAKES PHYTOPLANKTON HAPPY
Because atmospheric circulation patterns are shifting over the peninsula -- probably due to climate change -- there are now cloudy skies where there used to be sunshine and vice versa, said study co-author Martin Montes-Hugo of Rutgers University.
In the southern part of the peninsula, the clouds are decreasing and sunlight is melting the sea ice, freeing up more open water that sunlight can shine through, Montes-Hugo said by telephone.
"You have more open water and so you have light penetration, so the phytoplankton is happy in the south," he said, because like most plants, phytoplankton need sunlight for photosynthesis.
In the northern part of the peninsula closer to the warm equator there are more clouds, and sea ice is even more reduced than in the south. Changing atmospheric patterns are whipping up increasing winds in the area, churning the ocean water, which enables the phytoplankton to go deeper. At these deeper levels, the little plants can catch less sunshine.
"This makes phytoplankton mad," Montes-Hugo said. "It's not good for phytoplankton because you have less light."
Phytoplankton, like other plants, absorb the climate-warming greenhouse gas carbon dioxide; less phytoplankton means less of this gas will be absorbed.
A decrease in phytoplankton along the Antarctic peninsula results in less food for krill, the tiny crustaceans that small fish eat, and on up the food chain to Adelie penguins and other creatures.
Adelie penguins are moving southward because the extreme Antarctic climate they require is no long present in parts of the peninsula; Chin-strap penguins that can tolerate warmer temperatures are moving into the area, Montes-Hugo said.
(Editing by Philip Barbara)
