Bacterial communities of cryoconite holes of a temperate alpine glacier show both seasonal trends and year-to-year variability

• Published in: Annals of Glaciology
• Main Authors: PITTINO, FRANCESCA, Maurizio MAGLIO, Isabella GANDOLFI, Roberto Sergio AZZONI, Guglielmina DIOLAIUTI, Roberto AMBROSINI, Andrea FRANZETTI
• Other Authors: Pittino, F, Maurizio, M, Gandolfi, I, Roberto Sergio AZZONI, Guglielmina, D, Ambrosini, R, Franzetti, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2018
• Subjects: climate change; ice biology; microbiology; Annals of Glaciology
• Online Access: http://hdl.handle.net/10281/204459; https://doi.org/10.1017/aog.2018.16; https://www.cambridge.org/core/journals/annals-of-glaciology/article/bacterial-communities-of-cryoconite-holes-of-a-temperate-alpine-glacier-show-both-seasonal-trends-and-yeartoyear-variability/E3A0F4D4CFEBF5C0893476469CA873CF

Cryoconite holes are small depressions of the glacier surface filled with melting water and with a wind-blown debris on the bottom. These environments are considered hot spots of biodiversity and biological activities on glaciers and host communities dominated by bacteria. Most of the studies on cryoconite holes assume that their communities are stable. However, evidence of seasonal variation in cryoconite hole ecological communities exists. We investigated the variation of the bacterial communities of cryoconite holes of Forni Glacier (Central Italian Alps) during the melting seasons (July-September) 2013 and 2016, for which samples at three and five time-points, respectively were available. Bacterial communities were characterized by high-throughput Illumina sequencing of the hypervariable V5-V6 regions of 16S rRNA gene, while meteorological data were obtained by an automatic weather station. We found consistent trends in bacterial communities, which shifted from cyanobacteria-dominated communities in July to communities dominated by heterotrophic orders in late August and September. Temperature seems also to affect seasonal dynamics of communities. We also compared bacterial communities at the beginning of the melting season across 4 years (2012, 2013, 2015 and 2016) and found significant year-to-year variability. Cryoconite hole communities on temperate glaciers are therefore not temporally stable.