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Palmer LTER Map
Photo Credit: Hugh Ducklow/Palmer LTER
A map of the Antarctic Peninsula shows the core study region of the Palmer LTER in the blue box. The entire survey region is shown in the red box. The extended regional grid, based on satellite studies, is marked by the black line. The arrow points to Charcot Island, proposed site of new detailed process studies. Lines are spaced 100 kilometers apart and station spacing is 20 kilometers.

Heading south

A project such as SASSI represents a philosophical shift for the PAL LTER group as it prepares to enter a new, six-year funding cycle for the program next austral summer. The team will focus less on data collection and surveys, and more on understanding processes, developing models for prediction purposes, and using new instruments like the moorings for year-round observations.

“We want to find out not only what the changes have been [on the peninsula] but exactly how and why they’re happening,” explained Ducklow, a marine ecologist and co-director of The Ecosystems Center at the Marine Biological Laboratory in Woods Hole, Mass.

Martinson’s moorings are one component. Another new addition is an autonomous underwater vehicle (AUV) called a Slocum glider. The submersible robot, tested on the 2007 LTER cruise, will be able to carry a number of sensors that measure things like seawater salinity and temperature. Next season, the researchers hope to launch a small fleet of the AUVs.

“We’re trying to get away from what you see during one month from the ship,” Ducklow explained. “We’re going to get a vastly expanded spatial and temporal view of properties in our region.”

However, the biggest shift in the long-term study may prove to be more strategic than philosophical. The PAL LTER scientists have proposed extending their study area farther south along the peninsula, where they believe the ecosystem has seen less effect from climate change.

“By going farther south, into an area where the warming hasn’t really migrated into yet, we hope to have a better insight into what things used to be like,” Ducklow said. “We’ll be in place down there with observations over the next decade when the climate change carpet continues to unfold farther to the south.”

Fraser, a seabird ecologist from the Polar Oceans Research Group in Montana, said the prospect of moving into this sort of virgin territory is exciting because by the time the PAL LTER began in 1990, a process the scientists refer to as climate migration had already begun. Climate migration assumes that whole ecosystems will shift to a new location that better matches the original climate and environment.

“We can test very specific hypotheses about how we think that system is going to change as it warms due to climate migration,” Fraser said. “We are really seeing the entire mega-fauna of the Subantarctic starting to move into our region and displacing … polar species like Weddell seals and Adélie penguins.”

In fact, except for a more permanent ice cover, the new site to the south possesses similar characteristics to the current study area, even down to the bathymetry, the underwater topography of the area. A grid of deep canyons off Charcot Island mirrors a similar feature farther north. That’s important because the researchers believe the canyons play a role in the upwelling event driving the warm water onto the continental shelf.

“We want to be on the ground floor of change in that area,” Fraser said of the southern expansion. “In other words, we want to document it from the beginning.”

The PAL LTER scientists might have missed that chance in 1990, but Martinson noted the current study area has been a unique experience. “The opportunity to actually have a full sampling program in place in an area undergoing change this dramatic is once in a hundred lifetimes. It’s just pure serendipity that we’re in the right place at the right time to monitor exactly how this physical change is impacting the ecosystem.”

NSF-funded research in this story: Hugh Ducklow, The Ecosystems Center at the Marine Biological Laboratory; Doug Martinson, Lamont-Doherty Earth Observatory at Columbia University; and Bill Fraser, Polar Oceans Research Group.

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