Antarctic krill vertical migrations modulate seasonal carbon export
A J R Smith1,2, S Wotherspoon2, L Ratnarajah1
1Australian Antarctic Program Partnership, Institute for Marine and Antarctic Studies, University of Tasmania, nipaluna/Hobart, Tasmania, Australia.
Science (New York, N.Y.)
|January 23, 2025
Summary
Antarctic krill (Euphausia superba) vertical migration significantly impacts ocean carbon cycling. Models must account for seasonal migration patterns to accurately estimate carbon export, preventing overestimations in climate change assessments.
Area of Science:
- Marine biology
- Biogeochemistry
- Oceanography
Background:
- Vertical migration of marine organisms is a key pathway for biological carbon export.
- Biogeochemical models often oversimplify carbon cycling by migrating species due to limited data.
- Antarctic krill (Euphausia superba) play a significant role in Southern Ocean carbon dynamics.
Purpose of the Study:
- To quantify particulate organic carbon (POC) flux from Antarctic krill fecal pellets.
- To assess the contribution of krill vertical migration to deep-ocean carbon export.
- To improve the representation of krill's role in carbon cycling within biogeochemical models.
Main Methods:
- Utilized a numerical model integrated with one year of acoustic observations from East Antarctica.
- Estimated total POC flux based on krill fecal pellet production.
- Analyzed the depth and seasonality of krill migration patterns.
Main Results:
- Total POC flux from krill fecal pellets was estimated at 9.68 mg C m-2 day-1.
- A maximum of 25% of krill migrated below 200 m, exhibiting strong seasonality.
- Seasonal deep migrations transported less than 10% (1.28 mg C m-2 day-1) of the total krill POC flux to the deep ocean.
Conclusions:
- Krill vertical migration exhibits significant seasonality, influencing the magnitude and timing of carbon export.
- Accurate carbon flux estimates require incorporating the seasonal dynamics of krill migration.
- Failure to account for seasonality in models can lead to overestimations of carbon export, impacting climate policy.
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