Lichen species across Alaska produce highly active and stable ice nucleators
<p>Forty years ago, lichens were identified as extraordinary biological ice nucleators (INs) that enable ice formation at temperatures close to 0 <span class="inline-formula"><sup>∘</sup></span>C. By employing INs, lichens thrive in freezing environments that...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-07-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/2805/2023/bg-20-2805-2023.pdf |
| Summary: | <p>Forty years ago, lichens were identified as extraordinary biological ice
nucleators (INs) that enable ice formation at temperatures close to
0 <span class="inline-formula"><sup>∘</sup></span>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 <span class="inline-formula">−15</span> <span class="inline-formula"><sup>∘</sup></span>C, and <span class="inline-formula">∼30</span> %
initiate freezing at temperatures above <span class="inline-formula">−6</span> <span class="inline-formula"><sup>∘</sup></span>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.</p> |
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| ISSN: | 1726-4170 1726-4189 |