Comprehensive research and detailed satellite data have led scientists to believe that the changing climate is making its drastic presence felt not just on penguins (at the apex of the food chain) but also on the microscopic life in Antarctica (at the icy base of the southern ecosystem).
The research was carried out by scientists 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.
According to Hugh Ducklow, of the Marie Biological Laboratory at Woods Hole, the principal investigator for the Palmer LTER project, the new findings are scientifically significant, but they also are consistent with the climate trends on the Peninsula and other observed changes.
"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," 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.
In the north, where ice-dependent species are disappearing, sea ice cover has declined and wind stress has increased.
The wind intensity and reduced sea ice causes greater mixing of the surface ocean waters, which results in a deepening of the surface mixed layer that lowers primary productivity rates and causes changes in phytoplankton species.