Antarctic krill – shrimp-like crustaceans that inhabit the icy waters surrounding Antarctica – may be small (around 5cm) but they have an enormous total biomass, similar to that of the global human population. However, while humans pump ever more carbon into the atmosphere, krill are working in reverse. They are nature’s heroes, helping to transport carbon out of the atmosphere and store it deep inside the ocean.
Krill are best known for the key role they play in Southern Ocean ecosystems. They are central in its unique food web, linking the energy fixed by microscopic marine plants called phytoplankton to a wide range of iconic species including penguins, seals, whales, fish and squid. Krill are also fished commercially, and this major industry is valued at around US$0.3 billion per year (£0.28 billion).
Not only are they important for the food web and fisheries, our recent study finds they store at least 20 million tonnes of carbon in the deep ocean annually, equating to US$4-46 billion depending on the price of carbon. (By converting estimates of carbon sequestration to dollar values, our study enables a better comparison with other marine environments.)
