Author: Carolyn Gramling / Source: Science News
PORTLAND, ORE. — Penguins preserve records of Antarctic environmental change. The birds’ feathers and eggshells contain the chemical fingerprints of variations in diet, food web structure and even climate, researchers reported February 12 at the American Geophysical Union’s 2018 Ocean Sciences Meeting.
The Antarctic environment has changed dramatically in recent decades. Overfishing has led to a decline in krill, small swimming crustaceans that are a key food source for birds, whales, fish and penguins in the Southern Ocean. Climate change is altering wind directions, creating open water regions in the sea ice that become hot spots for life.
These changes have cascading effects on food webs and on the cycling of nutrients. “Penguins are excellent bioarchives of this change,” says Kelton McMahon, an oceanic ecogeochemist at the University of Rhode Island in Kingston.
Penguins are at the heart of the Antarctic food web, and their tissues are known to capture details about what they’ve eaten. Different food sources contain different proportions of carbon and nitrogen isotopes, forms of the elements with different numbers of neutrons. For example, food sources such as krill and fish have different amounts of nitrogen-15 relative to nitrogen-14. The tissues of penguins, such as feathers and eggshells, preserve these proportions.
Previous studies had already noted a large shift in isotopic values in penguin tissues in the last 80 years, but those studies couldn’t distinguish between shifts in the penguins’ diet versus climate-related shifts in the isotopic values of the microscopic creatures at the very bottom of the food web.
So McMahon and his colleagues created a tool to make this distinction — and ultimately to…The post Look to penguins to track Antarctic changes appeared first on FeedBox.