Abstract
The assessment of algal biodiversity in mountain glaciers is timely and critical. In this study, we evaluated the biodiversity of algae on an alpine glacier and their spatio-temporal variability in seven supraglacial habitats (snow, bare ice, bédières, water of cryoconite holes, dirt cones, sparse sediment, and cryoconite) over two years. Biovolume, diversity, and community structure were investigated using microscopy observations, providing a comprehensive quantitative and qualitative assessment of the algae dynamics. Algal communities were highly spatially and temporally variable. The community dynamics at the glacier scale were complex and structured by diverse ecological processes. The difference in species richness explained the major part (82.5%) of the variation in algal community composition among habitats. The snow was characterized by the higher local contribution to beta diversity (LCBD) values and by high replacement values. This habitat typically supported unique combinations of species and contributed greatly to glacier biodiversity (with 6 associated indicator taxa). Dirt cones, sparse sediment, and cryoconite communities showed high rates of species replacement, while the communities of bare ice, bédières, and water of cryoconite holes showed lower species richness. Bare ice was characterized by the lowest richness, due to the large dominance of Mesotaenium berggrenii, which bloomed at the end of the ablation period (biovolume 6 to 14-fold higher at late summer 2023 than in the other dates). Under warmer conditions, the forecasted decrease of snow and ice mass may remove the habitats that contribute most to the total biodiversity of the glacier, affecting the overall community dynamics and impacting the surrounding environments that benefit from the glacier’s resources.
Similar content being viewed by others
High prevalence of parasitic chytrids infection of glacier algae in cryoconite holes in Alaska
Impacts of deglaciation on biodiversity and ecosystem function
Evolution of snow algae, from cosmopolitans to endemics, revealed by DNA analysis of ancient ice
Data availability
Data are available on the following https://doi.org/10.5281/zenodo.16939622.
References
Anesio, A. M. & Laybourn-Parry, J. Glaciers and ice sheets as a biome. Trends Ecol. Evol. 27, 219–225 (2012).
Vitasse, Y. et al. Phenological and elevational shifts of plants, animals and fungi under climate change in the European alps. Biol. Rev. 96, 1816–1835 (2021).
Hotaling, S., Hood, E. & Hamilton, T. L. Microbial ecology of mountain glacier ecosystems: biodiversity, ecological connections and implications of a warming climate. Environ. Microbiol. 19, 2935–2948 (2017).
UN. General Assembly (77th sess.: 2022–2023). International Year of Glaciers’ Preservation, 2025: resolution/adopted by the General Assembly. https://digitallibrary.un.org/record/3998543
Zemp, M. et al. Community estimate of global glacier mass changes from 2000 to 2023. Nature 639, 382–388 (2025).
Huss, M. et al. Toward mountains without permanent snow and ice. Earth’s Future 5, 418–435 (2017).
Pepin, N. C. et al. Climate changes and their elevational patterns in the mountains of the world. Rev. Geophys. 60, eRG000730 (2022). (2020).
Milner, A. M. et al. Glacier shrinkage driving global changes in downstream systems. Proc. Natl. Acad. Sci. 114, 9770–9778 (2017).
Cauvy-Fraunié, S. & Dangles, O. A global synthesis of biodiversity responses to glacier retreat. Nat. Ecol. Evol. 3, 1675–1685 (2019).
Crosta, A. et al. Ecological interactions in glacier environments: a review of studies on a model alpine glacier. Biol. Rev. 100, 227–244 (2025).
Fjellberg, A. Paraxenylla norvegica sp. nov., the most Northern species of the genus (Collembola, Hypogastruridae). Zootaxa 2384, 65 (2010).
Valle, B. et al. The Unexplored Biodiversity of ‘Glacier Fleas’ (Hexapoda: Collembola): Taxonomy, Distribution and Ecology in the European Alps and Apennines. J. Zool. Syst. Evolutionary Res. 1616350 (2025).
Gobbi, M. & Lencioni, V. Glacial biodiversity: lessons from ground-dwelling and aquatic insects. Glaciers Polar Environ. 143 (2021).
Valle, B. et al. Biodiversity and ecology of plants and arthropods on the last preserved glacier of the apennines mountain chain (Italy). Holocene 32, 853–865 (2022).
Valle, B. et al. Glacial biodiversity of the southernmost glaciers of the European alps (Clapier and Peirabroc, Italy). J. Mt. Sci. 19, 2139–2159 (2022).
Steinbauer, M. J. et al. Topography-driven isolation, speciation and a global increase of endemism with elevation. Glob. Ecol. Biogeogr. 25, 1097–1107 (2016).
Muellner-Riehl, A. N. Mountains as evolutionary arenas: Patterns, emerging Approaches, paradigm Shifts, and their implications for plant phylogeographic research in the Tibeto-Himalayan region. Front Plant. Sci. 10, (2019).
Bosson, J. B. et al. Future emergence of new ecosystems caused by glacial retreat. Nature 620, 562–569 (2023).
Anesio, A. M., Hodson, A. J., Fritz, A., Psenner, R. & Sattler, B. High microbial activity on glaciers: importance to the global carbon cycle. Glob. Change Biol. 15, 955–960 (2009).
Wadham, J. L. et al. Ice sheets matter for the global carbon cycle. Nat. Commun. 10, 3567 (2019).
Wadham, J. L., Tranter, M., Tulaczyk, S. & Sharp, M. Subglacial methanogenesis: A potential Climatic amplifier? Global Biogeochem. Cycles 22, (2008).
Hood, E. et al. Glaciers as a source of ancient and labile organic matter to the marine environment. Nature 462, 1044–1047 (2009).
Hodson, A. et al. Glacial ecosystems. Ecol. Monogr. 78, 41–67 (2008).
Franzetti, A. et al. Temporal variability of bacterial communities in cryoconite on an alpine glacier. Environ. Microbiol. Rep. 9, 71–78 (2017).
Musilova, M., Tranter, M., Bennett, S. A., Wadham, J. & Anesio, A. M. Stable microbial community composition on the Greenland ice sheet. Front Microbiol. 6, (2015).
Takeuchi, N. Seasonal and altitudinal variations in snow algal communities on an Alaskan glacier (Gulkana glacier in the Alaska range). Environ. Res. Lett. 8, 035002 (2013).
Chen, Y. et al. Temporal variation of bacterial community and nutrients in Tibetan glacier snowpack. Cryosphere 16, 1265–1280 (2022).
Franzetti, A. et al. Potential sources of bacteria colonizing the cryoconite of an alpine glacier. PLOS ONE. 12, e0174786 (2017).
Lutz, S., Anesio, A. M., Edwards, A. & Benning, L. G. Linking microbial diversity and functionality of Arctic glacial surface habitats. Environ. Microbiol. 19, 551–565 (2017).
Hoham, R. W. & Remias, D. Snow and glacial algae: A Review1. J. Phycol. 56, 264–282 (2020).
Stibal, M. et al. Glacial ecosystems are essential to Understanding biodiversity responses to glacier retreat. Nat. Ecol. Evol. 4, 686–687 (2020).
Hågvar, S. et al. Ecosystem birth near melting glaciers: A review on the pioneer role of ground-dwelling arthropods. Insects 11, (2020).
Di Mauro, B. et al. Glacier algae foster ice-albedo feedback in the European alps. Sci. Rep. 10, 4739 (2020).
Cook, J., Edwards, A., Takeuchi, N. & Irvine-Fynn, T. Cryoconite: The dark biological secret of the cryosphere. Progress Phys. Geography: Earth Environ. 40, 66–111 (2016).
Boetius, A., Anesio, A. M., Deming, J. W., Mikucki, J. A. & Rapp, J. Z. Microbial ecology of the cryosphere: sea ice and glacial habitats. Nat. Rev. Microbiol. 13, 677–690 (2015).
Paul, F. et al. Glacier shrinkage in the alps continues unabated as revealed by a new glacier inventory from Sentinel-2. Earth Syst. Sci. Data. 12, 1805–1821 (2020).
Senese, A., Leidi, M. & Diolaiuti, G. A new enhanced temperature-index melt model including net solar and infrared radiation. Geografia Fisica E Dinamica Quaternaria. 44, 3–12 (2021).
Dory, F. et al. Morphological diversity of microalgae and cyanobacteria of cryoconite holes in Northern Victoria Land, Antarctica. J. Glaciol. 71, e37 (2025).
Utermöhl, H. Methods of collecting plankton for various purposes are discussed. SIL Commun. 1953–1996. 9, 1–38 (1958).
Komárek, J. & Anagnostidis, K. Süßwasserflora Von Mitteleuropa: Cyanoprokaryota (Spektrum, Akad., 2005).
Ettl, H. & Gärtner, G. Süßwasserflora von Mitteleuropa, Bd. 10: Chlorophyta II. (1999).
Laplace-Treyture, C., Derot, J., Prévost, E., Le Mat, A. & Jamoneau, A. Phytoplankton morpho-functional trait dataset from French water-bodies. Sci. Data 8, 40 (2021).
Druart, J. C. & Rimet, F. Protocoles d’analyse du phytoplancton de l’inra: prélèvement, dénombrement et biovolumes. INRA-Thonon Rapport SHL. 283, 96 (2008).
R Development Core Team. R: A language and environment for statistical computing and graphics. (2018).
Oksanen, J. et al. Package ‘vegan’. Community ecology package, version 2, 1–295 (2013).
Clarke, K. R. & Warwick, R. M. Similarity-based testing for community pattern: the two-way layout with no replication. Mar. Biol. 118, 167–176 (1994).
Ricotta, C. & Podani, J. On some properties of the Bray-Curtis dissimilarity and their ecological meaning. Ecol. Complex. 31, 201–205 (2017).
Legendre, P. & Gallagher, E. D. Ecologically meaningful transformations for ordination of species data. Oecologia 129, 271–280 (2001).
Legendre, P. & Legendre, L. Numerical ecology: developments in environmental modelling. Developments Environ. Modelling 20, 1–853 (1998).
Kuznetsova, A., Brockhoff, P. B. & Christensen, R. H. B. LmerTest package: tests in linear mixed effects models. J. Stat. Softw. 82, 1–26 (2017).
Lenth, R., Singmann, H., Love, J., Buerkner, P. & Herve, M. Package Emmeans. R package version 4.0–3. Am. Statistician (2018).
Dray, S. et al. Package ‘adespatial’. R Package 2018, 3–8 (2018).
Schmera, D., Podani, J. & Legendre, P. What do beta diversity components reveal from presence-absence community data? Let Us connect every indicator to an indicandum! Ecol. Ind. 117, 106540 (2020).
Csárdi, G. et al. Igraph: network analysis and visualization. 2.2.1 (2006). https://doi.org/10.32614/CRAN.package.igraph
De Cáceres, M., Legendre, P. & Moretti, M. Improving indicator species analysis by combining groups of sites. Oikos 119, 1674–1684 (2010).
Hill, M. J. et al. Local contributions to beta diversity in urban pond networks: implications for biodiversity conservation and management. Divers. Distrib. 27, 887–900 (2021).
Legendre, P. Interpreting the replacement and richness difference components of beta diversity. Glob. Ecol. Biogeogr. 23, 1324–1334 (2014).
Remias, D., Lütz-Meindl, U. & Lütz, C. Photosynthesis, pigments and ultrastructure of the alpine snow alga Chlamydomonas nivalis. Eur. J. Phycol. 40 (3), 259–268 (2005).
Brown, S. P., Olson, B. J. S. C. & Jumpponen, A. Fungi and algae co-occur in snow: an issue of shared habitat or algal facilitation of heterotrophs? Arct. Antarct. Alp. Res. 47 (4), 729–749 (2015).
Shamurailatpam, M. S., Ramanathan, A. & Raju, N. J. Nutrient dynamics in the Polar ice sheets and mountain glaciers. 381–406 (2022). https://doi.org/10.1002/9781119870562.ch17
Schuler, C. G. & Mikucki, J. A. Microbial ecology and activity of snow algae within a Pacific Northwest snowpack. Arct. Antarct. Alp. Res. 55 (1), 2233785 (2023).
Kawecka, B. Ecology of snow algae. Polish Polar Res. 7, (1986).
Kawecka, B. Biology and ecology of snow algae. Acta Hydrobiol. 23, 211–215 (1981).
Hartmann, D. L. Global Physical Climatology. Newnes. Vol.103, (2015).
Stibal, M., Elster, J., Šabacká, M. & Kaštovská, K. Seasonal and diel changes in photosynthetic activity of the snow alga Chlamydomonas nivalis (Chlorophyceae) from Svalbard determined by pulse amplitude modulation fluorometry. FEMS Microbiol. Ecol. 59, 265–273 (2007).
Stibal, M., Šabacká, M. & Kaštovská, K. Microbial communities on glacier surfaces in Svalbard: impact of physical and chemical properties on abundance and structure of cyanobacteria and algae. Microb. Ecol. 52, 644–654 (2006).
Remias, D. et al. Characterization of an UV- and VIS-absorbing, purpurogallin-derived secondary pigment new to algae and highly abundant in Mesotaenium berggrenii (Zygnematophyceae, Chlorophyta), an extremophyte living on glaciers. FEMS Microbiol. Ecol. 79, 638–648 (2012).
Remias, D., Holzinger, A. & Lütz, C. Physiology, ultrastructure and habitat of the ice alga Mesotaenium berggrenii (Zygnemaphyceae, Chlorophyta) from glaciers in the European Alps. Phycologia 48 (4), 302–312 (2009).
Siddiqui, K. S. et al. Psychrophiles. Annu. Rev. Earth Planet. Sci. 41, 87–115 (2013).
De Maayer, P., Anderson, D., Cary, C. & Cowan, D. A. Some like it cold: Understanding the survival strategies of psychrophiles. EMBO Rep. 15, 508–517 (2014).
Krug, L., Erlacher, A., Markut, K., Berg, G. & Cernava, T. The Microbiome of alpine snow algae shows a specific inter-kingdom connectivity and algae-bacteria interactions with supportive capacities. ISME J. 14, 2197–2210 (2020).
Joint, I. et al. Cell-to-Cell communication across the Prokaryote-Eukaryote boundary. Science 298 (5596), 1207–1207 (2002).
Croft, M. T., Warren, M. J. & Smith, A. G. Algae need their vitamins. Eukaryot. Cell. 5 (8), 1175–1183 (2006).
Amavizca, E. et al. Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus. Sci. Rep. 7, 41310 (2017).
Yang, G. L. et al. Differences in bacterial diversity and communities between glacial snow and glacial soil on the Chongce ice Cap, West Kunlun mountains. Sci. Rep. 6, 36548 (2016).
Xing, T., Liu, K., Ji, M., Chen, Y. & Liu, Y. Bacterial diversity in a continuum from supraglacial habitats to a proglacial lake on the Tibetan plateau. FEMS Microbiol. Lett. 371, fnae021 (2024).
Jia, P. et al. Habitat changes due to glacial freezing and melting reshape microbial networks. Environ. Int. 189, 108788 (2024).
Williamson, C. J. et al. Ice algal bloom development on the surface of the Greenland ice sheet. FEMS Microbiol. Ecol. 94, fiy025 (2018).
Stibal, M. et al. Algae drive enhanced darkening of bare ice on the Greenland ice sheet. Geophys. Res. Lett. 44, 11463–11471 (2017).
Kohshima, S. et al. Estimation of net accumulation rate at a Patagonian glacier by ice core analyses using snow algae. Glob. Planet Change 59, 236–244 (2007).
Pittino, F. et al. Bacterial communities of cryoconite holes of a temperate alpine glacier show both seasonal trends and year-to-year variability. Ann. Glaciol. 59, 1–9 (2018).
Sommer, C. et al. Rapid glacier retreat and downwasting throughout the European alps in the early 21st century. Nat. Commun. 11, 3209 (2020).
Fugazza, D. et al. Combination of UAV and terrestrial photogrammetry to assess rapid glacier evolution and map glacier hazards. Nat. Hazards Earth Syst. Sci. 18, 1055–1071 (2018).
Belloni, V., Fugazza, D., Hanson, K., Scaioni, M. & Di Rita, M. Assessing glacier thickness changes with multi-temporal UAV-derived dems: the evolution of Forni Glacier over the period 2014–2022. Int. J. Appl. Earth Obs. Geoinf. 140, 104547 (2025).
Acknowledgements
This study was co-funded by PRIN-2022 Grant 2022TT8XHN ‘Cold Case: the disappearing biodiversity of Italian glaciers’. We are grateful to the administration of Stelvio National Park for their support and to the staff of Forni and Branca Refuges for their warm welcome and support during field work.
Author information
Authors and Affiliations
Contributions
F.D.: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Resources, Software, Visualization, Writing (original draft preparation). R.A. and A.F.: Funding acquisition, Project administration, Resources, Supervision, Validation, Writing (review and editing). A.A., G.D., F.F., A.F., D.F., M.G., V.L., T.L., F.S.M., V.N., F.P., F.P., A.S., M. S., L. M.T., B.V., L.V., and M.C.: Resources, Validation, Writing (review and editing). B.L.: Conceptualization, Resources, Supervision, Validation, Writing (review and editing).
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Supplementary Material 1
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Reprints and permissions
About this article
Cite this article
Dory, F., Ambrosini, R., Ahmad, A. et al. Spatial and temporal variability of supraglacial algae on an Alpine glacier (Forni Glacier, Italy).
Sci Rep (2026). https://doi.org/10.1038/s41598-026-36705-w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-36705-w
Keywords
- Algae biodiversity
- Biovolume
- Community composition
- Glacier
- Italian Alps
Source: Ecology - nature.com
