References
[1] Manno, C., et al. (2020). Continuous moulting by Antarctic krill drives major pulses of carbon export in the north Scotia Sea, Southern Ocean. Nature Communications, 11, 6051. https://doi.org/10.1038/s41467-020-19956-7
[2] Cavan, E. L., Belcher, A., Atkinson, A., et al. (2019). The importance of Antarctic krill in biogeochemical cycles. Nature Communications, 10(1), 4742. https://doi.org/10.1038/s41467-019-12668-7
[3] Cavan, E. L., Mackay, N., Hill, S. L., Atkinson, A., Belcher, A., & Visser, A. (2024). Antarctic krill sequester similar amounts of carbon to key coastal blue carbon habitats. Nature Communications, 15(1), 7842. https://doi.org/10.1038/s41467-024-52135-6
[4] Greenspoon, L., Krieger, E., Sender, R., et al. (2023). The global biomass of wild mammals. Proceedings of the National Academy of Sciences, 120(10), e2204892120. https://doi.org/10.1073/pnas.2204892120
[5] Siegel, V. (2016). Biology and ecology of Antarctic krill. Advances in Polar Ecology. https://doi.org/10.1007/978-3-319-29279-3
[6] Atkinson, A., Hill, S. L., Pakhomov, E. A., et al. (2019). Krill (Euphausia superba) distribution contracts southward during rapid regional warming. Nature Climate Change, 9(2), 142–147. https://doi.org/10.1038/s41558-018-0370-z
[7] Meyer, B., Arata, J. A., Atkinson, A., et al. (2025). Adjusting the management of the Antarctic krill fishery to meet the challenges of the 21st century. Proceedings of the National Academy of Sciences, 122(37), e2412624122. https://doi.org/10.1073/pnas.2412624122
Antarctic Krill
These tiny crustaceans lock at least 20 million tonnes of carbon into the deep ocean every year - rivalling the carbon storage capacity of salt marsh, mangroves and seagrass.
At just six centimetres long, Antarctic krill are easy to overlook. But scientists are finding that this small, shrimp-like creature plays an outsized role in regulating the ocean's carbon cycle.
Krill feed on phytoplankton (carbon-rich algae) near the ocean surface. What they eat, they eventually excrete - and what they excrete sinks. Their dense faecal pellets carry carbon from the surface down into the deep ocean, where it can no longer escape into the atmosphere. Krill also mould (shed their shells) continuously as they grow, and these so-called exuviae sink too, contributing a comparable amount of carbon to the deep as the faecal pellets themselves [1]. When krill die, their sinking carcasses add yet another pulse of carbon to the deep. Across all these pathways, that carbon stays locked away for at least 100 years [2]. A 2024 study published in Nature Communications calculated that Antarctic krill sequester a comparable amount of carbon through their sinking faecal pellets alone as the world's key coastal blue carbon habitats - seagrass beds, salt marshes and mangrove forests [3]. Thus, the study estimates that the carbon storage provided by krill represents an ecosystem service worth billions of dollars to society.
But the little crustaceans are more than a carbon store. With an estimated biomass of 340–540 million tonnes, they are among the most abundant wild animals on Earth [4], and they are the primary food source for seals, penguins, seabirds and whales across the Southern Ocean [5]. They are the base on which almost all Antarctic life is built. Even animals that don't have krill on their menu depend on animals that do.
Both roles are now under pressure. Warming seas and shrinking sea ice, driven by climate change, are pushing krill populations southward and degrading the habitats their larvae depend on. Since the 1970s, the core krill distribution around the Antarctic Peninsula has shifted approximately 440 km southward [6]. At the same time, the krill fishing industry continues to grow, with catch limits that do not adequately account for the pressures climate change is placing on krill populations [7].
When krill decline, the ocean loses part of its capacity to store carbon, sustain its food webs, and buffer against climate change. Understanding and protecting Antarctic krill is therefore inseparable from protecting the ocean's role in the global climate system.
Antarctic Krill
These tiny crustaceans lock at least 20 million tonnes of carbon into the deep ocean every year - rivalling the carbon storage capacity of salt marsh, mangroves and seagrass.
At just six centimetres long, Antarctic krill are easy to overlook. But scientists are finding that this small, shrimp-like creature plays an outsized role in regulating the ocean's carbon cycle.
Krill feed on phytoplankton (carbon-rich algae) near the ocean surface. What they eat, they eventually excrete - and what they excrete sinks. Their dense faecal pellets carry carbon from the surface down into the deep ocean, where it can no longer escape into the atmosphere. Krill also mould (shed their shells) continuously as they grow, and these so-called exuviae sink too, contributing a comparable amount of carbon to the deep as the faecal pellets themselves [1]. When krill die, their sinking carcasses add yet another pulse of carbon to the deep. Across all these pathways, that carbon stays locked away for at least 100 years [2]. A 2024 study published in Nature Communications calculated that Antarctic krill sequester a comparable amount of carbon through their sinking faecal pellets alone as the world's key coastal blue carbon habitats - seagrass beds, salt marshes and mangrove forests [3]. Thus, the study estimates that the carbon storage provided by krill represents an ecosystem service worth billions of dollars to society.
But the little crustaceans are more than a carbon store. With an estimated biomass of 340–540 million tonnes, they are among the most abundant wild animals on Earth [4], and they are the primary food source for seals, penguins, seabirds and whales across the Southern Ocean [5]. They are the base on which almost all Antarctic life is built. Even animals that don't have krill on their menu depend on animals that do.
Both roles are now under pressure. Warming seas and shrinking sea ice, driven by climate change, are pushing krill populations southward and degrading the habitats their larvae depend on. Since the 1970s, the core krill distribution around the Antarctic Peninsula has shifted approximately 440 km southward [6]. At the same time, the krill fishing industry continues to grow, with catch limits that do not adequately account for the pressures climate change is placing on krill populations [7].
When krill decline, the ocean loses part of its capacity to store carbon, sustain its food webs, and buffer against climate change. Understanding and protecting Antarctic krill is therefore inseparable from protecting the ocean's role in the global climate system.