Regardless of doubts over the climate fixation with trace gases in the atmosphere, the workings of nature’s oceanic carbon cycle are worth investigating. The study says ‘The carbon sequestration potential of open-ocean pelagic ecosystems is vastly under-reported compared to coastal vegetation ‘blue carbon’ systems’, and ‘it is likely that Antarctic krill is amongst the world’s most important carbon-storing organisms.’
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Small marine crustaceans are as valuable as key coastal habitats for storing carbon and should be similarly protected, according to new research.
The study shows that a single species, Antarctic krill, store similar amounts of carbon to key ‘blue carbon’ habitats such as mangroves, saltmarshes and seagrasses, says Eurekalert.
However, krill are also impacted by global heating and potential overfishing, so should be considered for similar protections as other important habitats, say the researchers.
Krill are eaten by larger animals in the Southern Ocean around Antarctica such as whales, seals and penguins, but are also fished for food and fishing bait, and for use in aquaculture and dietary supplements.
Lead author Dr Emma Cavan, from the Department of Life Sciences at Imperial College London, said: “For the past decade we have been piecing together the role krill have in carbon cycling, finally resulting in this amazing finding that krill, and their poo, store similar amounts of carbon as some coastal marine plants.
“I hope this means we can now work towards conserving krill and their valuable Southern Ocean ecosystem with the same gumption as we are seagrasses and mangroves.”
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Serious value
Marine life has an important role in locking carbon away from the atmosphere in ocean systems, and the term ‘blue carbon’ was coined over a decade ago to describe the important role of coastal marine plants in this process.
However, the ocean has other ways to store carbon, away from the coasts, and one of these is through animals like krill. Krill are small (around 6cm) but extremely numerous crustaceans that live in the Antarctic seas.
They eat phytoplankton – microscopic plants that take carbon out of the atmosphere as they perform photosynthesis. When krill poo or moult their exoskeletons, the carbon they have absorbed sinks into the deep sea where it can stay for a very long time.
The new study shows that Antarctic krill lock at least 20 million tonnes of carbon into the deep ocean annually, which equates to $4-46 billion of storage value, depending on the price of carbon.
Co-author Professor Angus Atkinson, from Plymouth Marine Laboratory, said: “Antarctic krill are well known for being at the centre of the unique Southern Ocean ecosystem and supporting an important fishery. But this study paints another picture of krill – on their key role in storing carbon.”
Krill power
The power of krill for storing carbon comes from their huge populations, forming swarms of up to 30 trillion individuals that produce showers of large, fast-sinking faecal pellets and other waste products.
Co-author Dr Anna Belcher, based at the UK Centre for Ecology & Hydrology, added: “One of the amazing things about krill is that they form massive swarms, which can be over a kilometre in length. This drives a huge ‘rain’ of krill poo after feeding, making krill globally important for locking carbon away from the atmosphere. So, let’s make sure we look after these amazing crustaceans!”
The study also revealed that the depths that these waste products need to reach to remain stored away for at least 100 years were surprisingly shallow (average depth 381 metres), further enhancing their potential. In combination, these factors make the carbon storage from krill similar to that from coastal blue carbon plant stores.
Full article here.
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Image: The ocean carbon cycle [credit: IAEA]
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September 18, 2024 at 04:49AM
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