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Monday March 11, 2024, 5pm GMT+1


Sara Harðardóttir1,2,17, James S. Haile3, Jessica Louise Ray4, Audrey Limoges1,5, Nicolas Van Nieuwenhove1,5, Catherine Lalande6, Pierre-Luc Grondin6,7, Rebecca Jackson1,3, Katrine Sandnes Skaar4, Maija Heikkilä8, Jørgen Berge9,10, Nina Lundholm11, Søren Rysgaard12,13,14, Marit-Solveig Seidenkrantz15, Stijn De Schepper4,16, Eline D. Lorenzen3, Guillaume Massé2,7, Connie Lovejoy2,7, Sofia Ribeiro1

Millennial-scale variations in Arctic sea ice are recorded in sedimentary ancient DNA of the microalga Polarella glacialis

1Glaciology and Climate Department, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
2Département de Biologie, Université Laval, Québec, Québec, Canada.
3Globe Institute, University of Copenhagen, Copenhagen, Denmark.
4NORCE Norwegian Research Centre AS, Climate & Environment Department, Bergen, Norway.
5Department of Earth Sciences, University of New Brunswick, Fredericton, Canada.
6Amundsen Science, Université Laval, Québec City, Canada.
7Takuvik International Research Laboratory, Université Laval, Québec, Québec, Canada.
8Helsinki Institute of Sustainability Science, University of Helsinki, Finland.
9Department of Arctic and Marine Biology, UiT, The Arctic University of Norway, Tromsø, Norway.
10Centre for Autonomous Marine Operations and Systems, Department of Biology, Norwegian University of Science and Technology, NTNU, Norway.
11The Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
12Greenland Climate Research Centre, Greenland Institute of Natural Resources, Nuuk, Greenland.
13Arctic Research Centre, Department of Biology, Aarhus University, Aarhus C, Denmark.
14Centre for Earth Observation Science, University of Manitoba, Winnipeg, Canada.
15Paleoceanography and Paleoclimate Group, Arctic Research Centre, and Climate Centre, Department of Geosciences, Aarhus University, Aarhus, Denmark.
16Bjerknes Centre for Climate Research, Bergen, Norway.
17Marine and Freshwater Research Institute. Hafnarfjörður, Iceland.


Sea ice is a critical component of the Earth’s Climate System and a unique habitat. Sea-ice changes prior to the satellite era are poorly documented, and proxy methods are needed to constrain its past variability. Here, we demonstrate the potential of sedimentary DNA from Polarella glacialis, a sea-ice microalga, for tracing past sea-ice conditions. We quantified P. glacialis DNA (targeting the nuclear ribosomal ITS1 region) in Arctic marine and fjord surface sediments and a sediment core from northern Baffin Bay spanning 12,000 years. Sea ice and sediment trap samples confirmed that cysts of P. glacialis are common in first-year sea ice and sinking particulate matter following sea-ice melt. Its detection is more efficient with our molecular approach than standard micropaleontological methods. Given that the species inhabits coastal and marine environments in the Arctic and Antarctic, P. glacialis DNA has the potential to become a useful tool for circum-polar sea-ice reconstructions.