Glacier and ice sheet host diverse communities of microorganisms who thrive on the ice surface despite numerous stresses including freeze-thaw cycles, high UV irradiance, resource limitation and freezing temperatures. Some microbes become 'dormant' to cope with stress - persisting in a reversible state of low metabolic activity. But despite dormancy being common in nature, its prevalence is largely unknown on glaciers. In 2019 we went to Greenland & Iceland to study melting glacier surfaces, their microbes, and measured dormancy responses. We used BONCAT incubations, amplicon and metatranscriptomic sequencing, and ecological modelling to investigate active and dormant microbes and state-switching responses. We found that glacier surface microbial communities are comprised of both active and inactive organisms, which are capable of state-switching on timescales similar to the freeze–thaw cycles experienced on glacier surfaces. The fast state-switching responses may be particularly important considering future climate change - since short but extreme warming events (e.g. during winter) might trigger reactivation of dormant microbes & alter the structure, functioning and carbon cycling of these systems.
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Bradley J, Trivedi C, Winkel M, Mourot R, Lutz S, Larose C, Keuschnig C, Doting E, Halbach L, Zervas A, Anesio A, Benning L. (2023) Active and dormant microorganisms on glacier surfaces. Geobiology. doi: 10.1111/gbi.12535