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Suitability of the Coralline Alga Clathromorphum compactum as an Arctic Archive for Past Sea ice Cover
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  • Natasha Leclerc,
  • Jochen Halfar,
  • Steffen Hetzinger,
  • Phoebe Chan,
  • Walter Adey,
  • Alexandra Tsay,
  • Eric Brossier,
  • Andreas Kronz
Natasha Leclerc
University of Toronto

Corresponding Author:natasha.leclerc@mail.utoronto.ca

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Jochen Halfar
University of Toronto at Mississauga
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Steffen Hetzinger
Universit├Ąt Hamburg
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Phoebe Chan
University of Bergen and Bjerknes Centre for Climate Research
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Walter Adey
Department of Botany, Smithsonian Institution
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Alexandra Tsay
University of Geneva
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Eric Brossier
Association Nord-Est
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Andreas Kronz
Universitaet Goettingen
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Abstract

Arctic sea ice cover has been steeply declining since the onset of satellite observations in the late 1970s. However, the available annually resolved sea ice data prior to this time are limited. Here, we evaluated the suitability of annual trace element (Mg/Ca) ratios and growth increments from the long-lived annual increment-forming benthic coralline red alga, Clathromorphum compactum, as high-resolution sea ice cover c. It has previously been shown that growth and Mg/Ca of C. compactum are strongly light controlled and therefore greatly limited during polar night and underneath sea ice cover. We compare algal data from 11 sites collected throughout the Canadian Arctic, Greenland and Svalbard, with satellite sea ice data. Our results suggested that algal growth anomalies most often produced better correlations to sea ice concentration than Mg/Ca alone or when averaging growth and Mg/Ca anomalies. High Arctic regions with persistently higher sea ice concentrations and shorter ice-free seasons showed strongest correlations between algal growth anomalies and satellite sea ice concentration over the study period (1979-2015). At sites where ice breakup took place prior to the return of sufficient solar irradiance, algal growth was most strongly tied to a combination of solar irradiance and other factors such as temperature, suspended sediments, phytoplankton blooms and cloud cover. These data are the only annually resolved in situ marine proxy data known to date and are of utmost important to gain a better understanding of the sea ice system and to project future sea ice conditions.
Jan 2022Published in Paleoceanography and Paleoclimatology volume 37 issue 1. 10.1029/2021PA004286