Krill could be vital in climate change battle, say British Antarctic Survey researchers

They could turn out to be a significant accomplice in the battle against climate change.

Vast swarms of krill in the Southern Ocean are now believed to remove double the amount of carbon from the atmosphere than previously assumed by global models.

Scientists have been aware that krill produce carbon-rich faecal pellets that sink in the water column and transfer carbon from the atmosphere to the deep ocean.

But now researchers at the British Antarctic Survey in Cambridge have found that the process of moulting, in which they shred their exoskeletons, performs a similar function.

Dr Clara Manno, a marine ecologist at BAS and lead author of the paper published in Nature Communications last Friday, says: “This is exciting news because it almost doubles the previous estimate of how much atmospheric carbon is transported into deep ocean layers by krill.

“Our study reveals that large krill swarms could remove a significant amount of carbon from the atmosphere. Over the entire ocean, krill transfer 0.3 tonnes of carbon daily – equivalent to the daily domestic CO2 emissions of the UK.”

Antarctic krill (Euphausia superba) represent some of the highest concentrations of animal biomass in the world’s oceans – estimated to be more than 150 million tonnes. They are the main diet for whales, penguins and seals and also harvested for food by humans.

Working in the north Scotia Sea, in the Southwest Atlantic Sector of the Southern Ocean, where more than 50 per cent of all Antarctic krill are located, researchers collected krill moults over a year using a trap moored close to the seabed.

Co-author and ecologist Prof Geraint Tarling said: “Krill are really unusual crustaceans in moulting so frequently. In fact, they renew their exoskeleton every 10 to 14 days, releasing their old ones to sink towards the seabed, and taking carbon with it.

“We are trying to understand the impact of environmental change on krill stocks, not only as they are a key food source for the whales, seals and penguins that inhabit the Southern Ocean, but perhaps now as they are a more important method of removing carbon from the atmosphere.”

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