The Antarctic Peninsula’s beauty is renowned worldwide. For millennia, the entire length of the Western Antarctic Peninsula has supported a classic polar food web featuring ice-dependent species like Adélie penguins, crabeater and Weddell seals, and whales, as well as ice-avoiding species like gentoo penguins and fur seals. Much of that food web depends on a small, but mighty crustacean, which thrive in polynyas.
Krill - Small But Mighty
Many of the iconic Antarctic species share a taste for krill - the tiny crustacean responsible for converting phytoplankton blooms into energy rich food. In addition to supporting marine biodiversity, krill regulate the global carbon cycle and provide economic resources by supporting commercial fisheries. While individually small, collectively krill are one of the most important species in the Antarctic ecosystem and the backbone of the food web.
Climate change is now rewriting the rules and is splitting the Peninsula ecosystem into two distinct regimes: the Northern Peninsula and the Southern Peninsula.
A Changing Ecosystem: The Northern Peninsula
Krill, along with many other Antarctic species, are tied to sea ice. As the ice disappears in more northern waters, these species follow the ice south. What was once a resilient polar ecosystem on the Northern Peninsula is transforming into something new — one less defined by ice, less dominated by krill, and more fragile in the face of warming seas. This shift can be traced back to the loss of sea ice.
Adélie penguins, one of the most iconic ice-dependent species, tell this story most clearly. Colonies that once numbered in the tens of thousands are declining, with several projected to become endangered or even vanish altogether in coming decades. Meanwhile, gentoo penguins and fur seals, species that avoid ice, are moving in and expanding southward.
A Changing Ecosystem: The Southern Peninsula
For now, the colder climate of the southern Antarctic Peninsula has kept it more protected than the rapidly warming north. Winter sea ice still reliably forms here, and that stability helps sustain krill and the species that depend on them. In fact, some of these southern regions may offer habitat refuge into the future. Models suggest that waters in the Southern Peninsula could remain productive into the next century, especially for krill.
Conservation
There is currently a marine protected area (MPA) proposed for the Antarctic Peninsula which would provide a safeguard for this critical region and the array and abundance of life that lives there. This proposal is specifically designed to protect Antarctic krill during important life history stages, and to provide climate refugia for this keystone species. As the north warms, the southern region encompassed by the MPA provides critical habitat, providing an opportunity for krill to adapt.
