The comprehensive survey, the first in at least 24 years, was undertaken by Oceanites, a non-profit group that closely monitors penguins and other Antarctic seabirds, in collaboration with researchers from NASA and Stony Brook University in New York, reports CBS News.
In the Oceanites Survey, population size and population trends were summarized for the five penguin species that breed on the continent, using data collected from 660 locations across the continent, as well as 101 sources of on-the-ground colony counts and satellite photo analyses.
The survey shows a striking 50 percent decline in two penguin populations, the Adélies, and chinstraps, while the gentoo population has increased by 40 percent. The survey also identifies future changes that will affect the penguin populations. The survey report specifically looked at the Antarctic Peninsula, which has warmed an average of five degrees Fahrenheit over the last 60 years.
Penguins – The canaries in the coal mine
“In one generation, I have personally witnessed the precipitous decline of once-abundant Adélie and chinstrap penguin populations,” Oceanites founder and president Ron Naveen said in a statement. “These iconic birds are literally canaries in the coal mine. They provide critical insights into the dramatic changes taking place in the Antarctic.”
Naveen told Scientific American that the change in the populations of the three species was possibly the result of rapid warming in the peninsula during the second half of the 20th century, even though the region has cooled slightly since 1990.
Naveen speculates that melting glaciers and ice sheets could easily cause a change in the amount of krill and fish, a source of food for the penguins. He points out that the gentoos appear to have adapted to the change easier than the Adélies, which may be why they are thriving in the region.
Michelle LaRue, a research ecologist at the University of Minnesota, confirms the importance of sea ice for organisms like krill. “Krill need sea ice to survive,” she explains. She points out there is a strong correlation between reduced sea ice and decreased krill populations.
There is another indication that a change in temperature on the peninsula may be having an impact on reduced Adélies populations. Naveen notes that in East Antarctica, on the opposite side of the continent from the peninsula, Adélie numbers have actually grown. “it’s colder—there has not been a similar warming trend.”
Marconi and Emperor penguins are the other two species that were included in the survey, but there is not enough long-term population data on them to make any projections for their future. All five species are dependent on krill and fish for survival and are also important prey animals for leopard seals.
Antarctica’s penguins
There are five penguin species breeding in Antarctica: emperor, Adélie, chinstrap, gentoo, and macaroni. The emperor and Adélie are the only two which breed around the entire continent, while the other three are restricted to the northern sections of the Antarctic Peninsula (in addition to also breeding north of the Antarctic continent).
“We can now use advanced satellite technology and data analyses to better understand how these penguin populations are changing,” said associate professor Heather Lynch, who directs The Lynch Lab for Quantitative Ecology at Stony Brook University.
