Krill: Key to a Healthy Southern Ocean

Krill may be tiny, but their role in the Southern Ocean ecosystem is huge. These crustaceans are the center of the Antarctic marine food web, serving as a main food source for many of the region’s iconic animals, including blue whales; fur seals; and gentoo, chinstrap, and Adélie penguins. Even species that don’t eat krill—such as leopard seals, which feed mainly on penguins—rely indirectly on these crustaceans.

Because the abundance and location of krill affect almost every other animal in the Southern Ocean, proper management is essential to keep the region’s ecosystem balanced. But an increase in industrial fishing of krill has intensified competition for the linchpin species, particularly in penguin foraging grounds near the Antarctic Peninsula and in the Scotia Sea. The Antarctic Peninsula, where the krill fishery concentrates, is one of the fastest-warming regions in the world, and changes in the krill population—and the broader food web—are a direct result of rising ocean temperatures and reduced sea ice.

Beyond their importance in the food web, krill provide another critical service in the Southern Ocean: They are a critical global carbon sink, helping to mitigate climate change. Each year, they are able to store and move to the bottom of the ocean an amount of carbon equivalent to that produced by 35 million cars.

To counter the rising threats to krill, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), the management body charged with conserving biodiversity in Antarctica’s Southern Ocean, is considering a proposal put forth by Argentina and Chile in 2018 to establish a large marine protected area (MPA) in the Antarctic Peninsula region. Studies show that designating an MPA there would create a climate refuge for krill and other species and would protect the region’s unique marine ecosystem for generations to come. CCAMLR is also developing a long-term ecosystem-based fisheries management system for the krill fishery, which can work in conjunction with the MPA to sustain the interdependent relationships between this forage species and its predators, especially penguins, around the Antarctic Peninsula.