Tiny Antarctic creatures provide US$8.6 billion of carbon storage via their poo

A new analysis by an Imperial researcher for WWF shows krill play a vital role in keeping carbon out of the atmosphere.

The analysis, conducted by Dr Emma Cavan from the Department of Life Sciences (Silwood Park) at Imperial, suggests krill should be valued beyond their worth as a fished resource.

Life on Earth clearly has an important role in carbon cycling and sequestration. Dr Emma Cavan

Krill are small but extremely numerous crustaceans that live in the Antarctic seas. They eat phytoplankton – microscopic plants that take carbon out of the atmosphere when they perform photosynthesis. When krill excrete faeces or moult their exoskeletons, this carbon is locked away in the deep sea.

The new report found that these processes sink the equivalent of 23 megatonnes of carbon annually in just one area of the Southern Ocean. Keeping this carbon out of the atmosphere, which would otherwise contribute to global heating, is now estimated to be worth US$15.2 billion per year - $8.6bn for the faeces and an additional US$6.6 billion for the shedding of exoskeletons.

This is in contrast to the annual worth of the Antarctic krill fishery, which is 60 times lower at about US$0.25 billion. The report ‘Antarctic krill: Powerhouse of the Southern Ocean’, was released today by the World Wide Fund for Nature (WWF).

Important role

Dr Cavan said: “We have valued just some of the ways that adult krill can store carbon showing their relevance to society. The numbers we report here will likely only increase once we are able to include other aspects of carbon storage by adult and larval krill in our assessments, such as sinking dead bodies and migration. Life on Earth clearly has an important role in carbon cycling and sequestration.”

Krill are harvested to make aquaculture feed, livestock and pet feed, and supplements for human consumption. They are also important natural prey for whales, seals, penguins and birds, which are sometimes caught as bycatch in krill fishing operations.

Management of krill fishing in the Southern Ocean is currently considered sustainable, but centres on making sure there are enough krill to support natural predators, and that the fishing of krill itself is able to continue year after year.

However, little attention has been given to assessing the significance of krill to the carbon cycle. The report recommends prioritising improved protection of Antarctic krill rather than expanded industrial harvesting.

Report co-author Emily Grilly, Antarctic Conservation Manager at WWF, said: “Emerging research is revealing that Antarctic krill play an important role in the global carbon cycle and their worth in the ecosystem is valuable not only to wildlife, but also humanity.

“Krill are individually small but collectively mighty. That certainly applies to their ability to store carbon and help maintain stable climatic conditions that are beneficial for humanity. Antarctic krill are worth more to nature and people left in the ocean than removed.”

Rhona Kent, Polar Oceans Specialist at WWF UK, said: “The Southern Ocean is the largest blue carbon sink in the world and has taken up about 40% of the carbon dioxide released as a result of human activity. As outlined in this report, we are just beginning to understand the role that key species such as Antarctic krill play in the process of carbon capture and storage.”

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Read the full report on the WWF website.