12 Jan 2023
12 Jan 2023
Status: this preprint is currently under review for the journal BG.

Lichen species across Alaska produce highly active and stable ice nucleators

Rosemary J. Eufemio1,2, Ingrid de Almeida Ribeiro3, Valeria Molinero4, Mischa Bonn5, Todd L. Sformo3, Gary A. Laursen6, Janine Fröhlich-Nowoisky7, and Konrad Meister1,2,7 Rosemary J. Eufemio et al.
  • 1Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA
  • 2Biomolecular Sciences Graduate Programs, Boise State University, Boise, ID 83725, USA
  • 3University of Utah, 84112 Salt Lake City, UT, United States
  • 4Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
  • 5High Latitude Mycological Research Institute, University of Montana, Missoula, MT 59801, USA
  • 6Max Planck Institute for Chemistry, 55128 Mainz, Germany
  • 7Max Planck Institute for Polymer Research, 55128 Mainz, Germany

Abstract. Forty years ago, lichens were identified as extraordinary biological ice nucleators (INs) that enable ice formation at temperatures close to 0 °C. By employing INs, lichens thrive in freezing environments that surpass the physiological limits of other vegetation, thus making them the majority of vegetative biomass in northern ecosystems. Aerosolized lichen INs might further impact cloud glaciation and have the potential to alter atmospheric processes in a warming Arctic. Despite the ecological importance and formidable ice nucleation activities, the abundance, diversity, sources, and role of ice nucleation in lichens remain poorly understood. Here, we investigate the ice nucleation capabilities of lichens collected from various ecosystems across Alaska. We find ice-nucleating activity in lichen to be widespread, particularly in the coastal rainforest of Southeast Alaska. Across 29 investigated lichen, all species show ice nucleation temperatures above −15 °C and ~30 % initiate freezing at temperatures above −6 °C. Concentration series of lichen ice nucleation assays in combination with statistical analysis reveal that the lichens contain two subpopulations of INs, similar to previous observations in bacteria. However, unlike the bacterial INs, the lichen INs appear as independent subpopulations resistant to freeze-thaw cycles and against temperature treatment. The ubiquity and high stability of the lichen INs suggest that they can impact local atmospheric processes and that ice nucleation activity is an essential trait for their survival in cold environments.

Rosemary J. Eufemio et al.

Status: open (until 23 Feb 2023)

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  • RC1: 'Comment on bg-2022-239', Anonymous Referee #1, 22 Jan 2023 reply

Rosemary J. Eufemio et al.

Rosemary J. Eufemio et al.


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Short summary
Lichens, the dominant vegetation in the Arctic, contain ice nucleators (INs) that enable freezing close to 0 °C. Yet the abundance, diversity, and function of lichen INs is unknown. Our screening of lichens across Alaska reveal that most species have potent INs. We find that lichens contain two IN populations which retain activity under environmentally relevant conditions. The ubiquity and stability of lichen INs suggests that they may have considerable impacts on local atmospheric patterns.