Surrounding the continent of Antarctica, the Southern Ocean plays an outsized role in the fight against climate change. It is one of the largest regional ocean sinks for atmospheric CO2, partly due to Antarctic krill, small crustaceans at the center of the region’s food web.
Krill swarms feed on carbon-capturing algae near the surface of the water, then swim to lower depths, dropping their carbon-filled waste in the water at the bottom of the ocean. In this way, they act as a giant conveyor belt, constantly moving carbon down from the surface. Krill swarms can number in the trillions of individuals, and the carbon they store in the deep ocean is equivalent to the yearly emissions of 35 million cars.
Unfortunately, krill and the species that depend on them are under increasing threat, both from climate change and localized industrial fishing.