Antarctic Long-Term Ecological Research site turns 30

Researchers have documented significant ecological changes to the Antarctic Peninsula thanks to the long-running National Science Foundation program

The Long-Term Ecological Research site at Palmer Station, Antarctica, celebrates its 30th field season this year. Thanks to this long-running research program, scientists have consistently tracked environmental changes taking place along the Antarctic Peninsula, one of the fastest-warming regions on Earth, over the past several decades. Researchers have also seen how those changes have rippled through the food web, affecting everything from microscopic ocean plants and tiny crustaceans to penguins and other seabirds and marine mammals.

Data collected from the Palmer LTER helps researchers understand not only how climate change is disturbing the marine ecosystem of the Antarctic Peninsula, but also gives them an idea of what the coldest places on Earth might look like in the coming decades.

“I think the LTER is going to help guide us in understanding where the polar regions of this planet are going to go,” said Oscar Schofield, an oceanographer at Rutgers University and lead Principal Investigator of the Palmer LTER. “If you didn't have this long-term dataset, you're not in a position to understand why the ecology changes.”

How LTER began

The National Science Foundation established the LTER network in 1980 so researchers could study environmental and ecological changes that happen over the course of decades. Ecologist John Magnuson dubbed these changes “the invisible present” because they're hard for any one person to make sense of in a lifetime.

Photo Credit: Mike Lucibella

A molting Gentoo penguin flaps its wings on a patch of moss near the coastline at Cierva Point along the Antarctic Peninsula.

“It is the unusual person who senses with any precision changes occurring over decades,” Magnuson wrote in a 1990 paper. “At this time scale, we are inclined to think of the world as static, and we typically underestimate the degree of change that does occur.”

The LTER network started with six locations for scientists to conduct research. The goal was to collect similar data year after year in a variety of ecosystems, analyze what long-term changes were happening, and eventually compare what was happening at each site to the others. Additional locations were added over the years, and the LTER network now consists of more than 30 research sites throughout the United States, Tahiti, and Antarctica, each focused on a different ecosystem.

NSF selected Palmer Station to be the first LTER site in Antarctica in 1990, and the first field season for researchers started the following year. The initial goal was to monitor sea ice and ocean conditions from year to year and observe populations of penguins and other animals that call the Antarctic Peninsula home.

Researchers had already been observing penguins, seals, and whales around Palmer Station at that time, but joining the LTER network allowed them to track many components of the Antarctic Peninsula marine ecosystem simultaneously.

The core idea of LTER research at Palmer Station is that sea ice is critical to the ecology of the region, according to Schofield. How much ocean is covered by ice affects how much food and habitat is available for animals like penguins and seals that call the peninsula home.

“We've been tracking how food webs are changing as you take away this structural element,” he said.

A change in sea ice

Palmer LTER has captured major environmental changes in the Antarctic Peninsula region over the past 30 years. Interestingly, individual researchers have seen increasingly visible changes during this time, contrary to what Magnuson suggested in 1990. Sea ice has declined, glaciers have retreated, and the weather has overall become warmer, wetter, and stormier.

“Palmer station now - at least our study area - doesn't look anything at all like it did when I first started,” said Bill Fraser, an ecologist with the Polar Oceans Research Group who has been studying Adélie penguins around the Antarctic Peninsula since the mid-1970s. “It is completely different. You can just about pick the variable and it's changed in some way.”

When Fraser first started doing research at Palmer Station, sea ice was predictable, the weather was consistently cold, and it rarely rained.

“Rain was something you talked about at dinner,” he said. “It was always snow.”

But as time progressed, Fraser saw the system start to change. There was more humidity in the air, summer precipitation switched from snow to rain, and the sea ice became less predictable from season to season.

The sea ice season, which was historically around six months long, is now around three to four months long, said Sharon Stammerjohn, a climate scientist with the Institute for Arctic and Alpine Research at the University of Colorado Boulder who has studied sea ice around the Antarctic Peninsula.

In addition, the Marr Piedmont Glacier, which sits on Anvers Island behind Palmer Station, has retreated by hundreds of meters, exposing previously hidden islands and mountain peaks.

Stammerjohn returned to Palmer Station in 2017 for the first time since 1994 and was stunned at how different the landscape looked. “I was shocked to see how much the glacier had retreated,” she said. “The change was just phenomenal.”

Major ecological shifts

The sea ice changes have had major impacts to the food web in the peninsula area. The biggest visible change researchers have noted is the shift in penguin species living on the peninsula. Historically, the area was home to thousands of breeding pairs of Adélie penguins. In 1975, there were about 15,000 breeding pairs of Adélie penguins around Palmer Station. Now there are less than 2,000 breeding pairs, according to Fraser.

Photo Credit: Jeffrey Keitzmann (2002 image) and Cynthia Spence (2015 image).

These images show how far the Marr Ice Piedmont, the glacier behind Palmer Station, retreated from 2002 to 2015.

As Adélie penguin populations on the peninsula have shrunk, sub-Antarctic species like Chinstrap and Gentoo penguins have migrated in. Chinstraps and Gentoos historically bred on islands in the South Atlantic Ocean, but they have been moving south along the Antarctic Peninsula over the past several decades. In 1975, there were almost no Chinstrap or Gentoo penguins in the Palmer area; now, there are more than 3,500 breeding pairs of Gentoos and several hundred pairs of Chinstraps.

“As things warm up, species move south, so the system will go from Antarctic to sub-Antarctic,” said Maria Vernet, one of the NSF Antarctic Organisms and Ecosystems Program Officers. “And that's what's happening at the tip of the peninsula.”

Adélie penguins evolved in a polar desert and their life histories are tied to sea ice. So the changes to the peninsula have caused Adélie populations to plummet while Chinstraps and Gentoos have flourished, being more adapted to the warmer, wetter conditions.

“Here we have an environment with no sea ice or very little sea ice, enormous amounts of rain in the summer, and incredible amounts of snow in the winter and the spring,” Fraser said. “That environment is not conducive to the life history of an Adélie penguin. They just can't make it in these really wet, snowy conditions.”

Changing species demographics aren't unique to Palmer Station - researchers see these effects in many different ecosystems, thanks to the LTER network.

“A common response over several of the LTER sites is fundamental change in species distributions,” said Karla Heidelberg, one of the NSF Antarctic Organisms and Ecosystems Program Officers. “We're tipping the scales to where the system used to be favored by one organism, it's now favored by a different organism.”

The peninsula's future

The Antarctic Peninsula is at the boundary between a cold, dry polar climate and a warmer, wetter subpolar climate. The boundary at which those environments meet has been moving south as warmer temperatures push further into Antarctica due to climate change, and LTER researchers predict it will continue to do so in the future.

“Palmer Station is at that hinge point right now - some years it looks like a hotter north some years it looks like a colder south,” Schofield said. “We expect eventually that warmer northern climate to dominate much more over time. And that will ripple through the food web.”

Fraser predicts that as the peninsula warms further, more sub-Antarctic species will migrate in, including elephant seals, fur seals, and brown skuas, seabirds that prey on Adélie penguins and their chicks.

“I think it's going to be a really different system, even different than it is today,” Fraser said. “I don't see that we're going to go back to the polar system that we once had down there.”

Thanks to the LTER network, researchers will continue tracking these changes over the coming decades.

“This program is a great example of the value of long-term science,” Heidelberg said. “It's a big commitment for NSF, but it's a commitment we're willing to continue because we see the value in better understanding how the environment changes with a changing climate.”

This research is supported by the National Science Foundation, which manages the U.S. Antarctic Program.