Climate-related Changes on the Antarctic Peninsula Being Driven from the Top and the Bottom of the Ecosystem

Scientists have long established that the Antarctic Peninsula is one of the most rapidly warming spots on Earth. Now, new research using detailed satellite data indicates that the changing climate is affecting not just the penguins at the apex of the food chain, but simultaneously the microscopic life that is the base of the ecosystem.

The research was published in the March 13 edition of Science magazine by researchers with the National Science Foundation's (NSF) LTER (Long Term Ecological Research) program. The LTER, which has 26 sites around the globe, including two in Antarctica, enables tracking of ecological variables over time, so that the mechanisms of climate change impact on ecosystems can be revealed. The specific findings were made by researchers with the Palmer LTER, using data collected near Palmer Station and from the research vessel Laurence M. Gould. Both Palmer Station and the Laurence M. Gould are operated by NSF's Office of Polar Programs.

Hugh Ducklow, of the Marie Biological Laboratory at Woods Hole, the principal investigator for the Palmer LTER project, said that the new findings are scientifically significant, but they also are consistent with the climate trends on the Peninsula and other observed changes.

However, it took new scientific tools and analytical work by post-doctoral fellow Martin Montes Hugo to verify scientifically what scientists had been inferring from other changes for some time.

"I have to say the findings weren't a surprise; I think with the weight of all the other observations that we had on changes happening to organisms higher up in the food chain, we thought that phytoplankton weren't going to escape this level of climate change," Ducklow said. "But it took Martin to have all the right tools and the abilities to go in and do the analysis and prove what we suspected."

Those data, gathered over years, were essential to tracking patterns that supported the new findings.

"That's the beauty of the LTER program," he added.

Over the past 50 years, winter temperatures on the Peninsula have risen five times faster than the global average and the duration of sea-ice coverage has decreased. A warm, moist maritime climate has moved into the northern Peninsula region, pushing the continental, polar conditions southward.

As a result, the prevalence of species that depend on sea ice, such as Adelie penguins, Antarctic silverfish and krill, has decreased in the Peninsula's northern region, and new species that typically avoid ice, such as Gentoo and Chinstrap penguins, and lanternfish are moving into the habitat.

The LTER researchers show that satellite data on ocean color, temperature, sea ice and winds, indicate that phytoplankton at the base of the food chain are also responding to changes in sea-ice cover and winds driven by climate change. However, there are contrasting changes in northern and southern regions, and the satellite and ground-based data provide insights into the forcing mechanisms for each region.

The researchers weren't surprised that primary productivity in the waters of the Peninsula has changed dramatically over the last 20 years. But the contrasting changes in the north and south were a surprise.