Disappeared ice, vanishing life: The end of the largest glacier of the Bergamo Alps (Italy) and the consequences for its endemic biodiversity

To date, the direct effects of complete glacier disappearance on the specialized fauna associated with this habitat have never been investigated in situ. The Trobio glacier, once the largest in the Bergamo Alps (Italy), completely vanished in 2023 due to climate-induced retreat. This study reconstructs Trobio glacier’s evolution from the Little Ice Age to its disappearance and assesses the impact of glacier extinction on two cryophilic endemic terrestrial arthropod species: the ground beetle Nebria tresignore and the springtail Desoria orobica. Historical maps, literature and recent field data were used to trace glacier changes, while biological surveys evaluated species occurrence to be compared with past (last 10 years) records. These data reveal a direct link between the recorded glacier retreat and species elevational shift: Nebria tresignore shifted upslope about 30 m a-1 following glacial retreat. Desoria orobica showed a dramatic population collapse, with average densities dropping from 80 to < 4 individuals per sample since 2020, likely due to the deeply modified glacial environment. These findings highlight the vulnerability of glacier-dependent biodiversity and the urgent need to document glacier extinction and to identify and protect microrefugia for cold-adapted species in rapidly changing alpine environments.