Understanding Change in the Antarctic

The Antarctic Peninsula is warming significantly faster than the global average, which is already leading to profound changes to the region’s food web.

Curious king penguins investigate the gear used to take sediment cores from ponds around penguin colonies. Cores help reconstruct the occupation history of penguins and seals.

Lights of the Ocean Endeavor shimmer as the expedition team returns to the ship after an evening identifying humpback and southern right whales in Cierva Cove, Antarctic Peninsula.

Professor McMahon stops for a selfie while guiding guests back to the zodiacs after a great day of observing penguins in their natural habitat on Carcass Island, Falkland Islands (Islas Malvinas).

The Antarctic food web in action: a 3-meter-long leopard seal seeks its next meal—an unlucky macaroni penguin entering the waters of Royal Harbor, South Georgia Island.

A black-browed albatross feeds its chick with a regurgitated mixture of fish, squid and krill that it foraged from the productive waters around the Falkland Islands (Islas Malvinas).

A whale’s tail signals an imminent deep dive, potentially to 100 meters or more in search of krill and small fish, in the frigid waters of Cierva Cove, Antarctic Peninsula.

In February, GSO professor Kelton McMahon participated in an Antarctic research cruise as part of a multi-year project funded by the National Science Foundation (NSF). The goal: to study how the Southern Ocean food web has responded to environmental changes in the past, and predict how the ecosystem might respond to a changing climate in the future.

Penguins play a pivotal role in Dr. McMahon’s research. The charismatic creatures serve as sentinel species for environmental change, and they occupy a central node in the Southern Ocean food web, recording geochemical clues about diet and migration patterns in their tissues. Dr. McMahon spent three weeks in the Antarctic gathering samples of penguin feathers and eggshells and conducted paleontological excavations to collect penguin feathers and eggshells that are hundreds to thousands of years old.

Now Dr. McMahon is working with his students at the newly built Ocean Ecogeochemistry Laboratory at GSO to compare the isotope values of modern penguin tissues to historic museum archives and ancient excavated samples. With his national and international research partners, Dr. McMahon will use these data to test hypotheses about how both historic whaling in the 1800s and early 1900s and rapid warming in the past century have altered the food web structure and population dynamics of Antarctic penguins.

Graduate School of Oceanography

Understanding Change in the Antarctic

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