Surface aggregations of Calanus finmarchicus during the polar night

Abstract While marine ecosystems in polar areas were thought to be mostly inactive during the polar night, recent observations in the Arctic highlight that dynamic biological interactions occur across all trophic levels. One particularly interesting observation made repeatedly is the occurrence of C...

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Bibliographic Details
Published in:ICES Journal of Marine Science
Main Authors: Espinasse, Boris, Daase, Malin, Halvorsen, Elisabeth, Reigstad, Marit, Berge, Jørgen, Basedow, Sünnje L
Other Authors: Woodson, Brock C, Norwegian Research Council, NRC, Tromsø Forskningsstiftelse, European Union
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press (OUP) 2022
Subjects:
Ecology
Aquatic Science
Ecology, Evolution, Behavior and Systematics
Oceanography
Arctic
Calanus finmarchicus
Climate change
polar night
Sea ice
Copepods
Online Access:http://dx.doi.org/10.1093/icesjms/fsac030
https://academic.oup.com/icesjms/article-pdf/79/3/803/43513510/fsac030.pdf
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Summary:Abstract While marine ecosystems in polar areas were thought to be mostly inactive during the polar night, recent observations in the Arctic highlight that dynamic biological interactions occur across all trophic levels. One particularly interesting observation made repeatedly is the occurrence of Calanus finmarchicus, a key species at the base of the food web, in the upper part of the water column in early January. This contrasts with the confirmed life cycle of this copepod, which predicts descent to overwintering depths in autumn and ascent at the end of the winter. Here, we compiled 6 years of data from the polar night to explore this unusual behaviour and to investigate the underlying mechanisms that may cause these surface aggregations. Highest abundance of C. finmarchicus in surface waters was closely related to Polar Surface Water in the vicinity of the sea ice edge. A total of six hypotheses are assessed to explain this distribution pattern, which includes passive transport and active behaviour as a way to improve survival chances or food access. In the context of climate change and sea ice decrease, the presence of lipid-rich copepods in cold surface waters could be a key parameter in driving the spatial distributions of top predators in the Arctic.

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