Monday, February 15, 2016

Antarctica’s most populous colony of Adélie penguins once may have been nearly twice the size it is today, UNCW biology and marine biology professor Steven D. Emslie and his research team discovered on a recent trip to the continent. Clues about why the colony grew so large and what has since caused a population decline could help scientists chart the penguins’ response to changes in climate and food resources.

During a mid-January research excursion to Cape Adare in the northern Ross Sea, Emslie found evidence that the colony, consisting of more than 338,000 breeding pair on a lower terrace, had once also covered the vast upper terrace. As large as that number sounds, Emslie conservatively estimates the former “supercolony” at Cape Adare once included more than 500,000 breeding pairs, or more than 1 million penguins.

His assessment, based on an examination of abandoned nesting sites, stems from collaborative research conducted by UNCW, Louisiana State University and the University of California at Santa Cruz under grants from the National Science Foundation totaling nearly $1.28 million. The University of Saskatchewan also is a participant in the research.

Emslie hypothesizes there may have been a huge influx of penguins to the colony at Cape Adare beginning about 2,000 years ago, followed by a decrease to its current number. The penguins apparently abandoned a large part of their southern Ross Sea area breeding ground, possibly forced north to Cape Adare as a climate shift caused ice to block access to the beach for nesting.

Emslie’s research partner at LSU, Michael Polito ’01, ’12 Ph.D., is an assistant professor of oceanography and coastal sciences and principal investigator for the overall project. UNCW graduate student Ashley McKenzie also helped collect samples on this trip.

The team will use radiocarbon dating to pinpoint the age of the nests and stable isotope analysis to determine the penguins’ diets at the time the upper-terrace colony was active. Analyzing that information will allow scientists to better understand how these penguins and the ecosystems on which they depend will respond to contemporary challenges such as global warming and expanded commercial fishing, Emslie and Polito explained.

The continent’s frigid climate is ideal for researching the progress of species over tens of thousands of years, Emslie said. “Only in Antarctica do you find the long-term preservation of tissues in soil – frozen in time – that provide so much information about living species in the same place where they still occur today.”

Emslie has kept a blog of his trips to Antarctica, as well as photos and a video showing the remnants of the supercolony at Cape Adare. Visit the UNCW research page for a fuller description of the project.

-- Tricia Vance

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