24 February 2023 | 14:00 - 15:30 (GMT+1)
Open Session - HYBRID
Room: Hörsaal 5
Session Conveners: Fabiana Canini (University of Tuscia, Italy); Laura Zucconi (University of Tuscia, Italy)
Session Description:
The Arctic, Antarctic, and Alpine habitats are experiencing the fastest warming rates on the planet. Warming is leading to longer ice-free seasons in the Arctic and Alpine regions, as well as an overall greening of terrestrial areas leading to increased microbial activity, which could have dramatic effects on the degradation of carbon pools in permafrost and positive feedback to global climate change. Climate change in Antarctica, on the other hand, is expected to result in the extinction of unique and well-adapted terrestrial ecosystems, owing to changes in temperature and precipitation regimes, as well as in physicochemical properties and the invasion of allochthonous, more competitive species. Given the crucial role of microorganisms in biogeochemical cycles, understanding the diversity and ecology of terrestrial ecosystems of these highly threatened environments, including the ecological drivers that shape their diversity, and their functionality, may be a key to understanding how biogeochemical cycles will respond to large-scale environmental changes. In this light, this session invites abstract submissions dealing with the diversity and functional adaptations of Arctic, Antarctic, and Alpine terrestrial ecosystems in relation to different environmental conditions, with the aim to shedding light on the potential effects of climate change on these ecosystems.
Presentations:
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unfold_morePolar and Alpine soils: little explored habitats harbouring cold-adapted fungal life - Keynote Presentation
Pietro Buzzini1; Ciro Sannino1; Luigimaria Borruso2; Gianmarco Mugnai1; Alessandro Bernetti1; Daniele Andreani1; Benedetta Turchetti1
1University of Perugia (Italy); 2Free University of Bozen (Italy)Abstract:
Polar and Alpine cold habitats harbour the life of both psychrophilic and psychrotolerant microorganisms, which have developed specific mechanisms of cold adaptation. The impact of global warming on cold habitats (e.g., Antarctica, Alpine glaciers, etc.) is amplifying every year. Therefore, they can be considered sentinel areas for studying the effect of climate changes on cold-adapted microbial diversity.
Soil, permafrost, brine, ice and debris samples were collected from Antarctic and Alpine sites. Fungal (yeasts and filamentous fungi) diversity was investigated via NGS targeting of ITS region (Illumina Miseq). Bioinformatic analysis of raw sequences was performed by Qiime 2 (https://qiime2.org/). The taxonomic assemblage of fungal communities and their interaction with abiotic parameters were studied by diversity indices, linear discriminant analysis effect size (LEfSe) and Pearson correlations.
OTUs (classified at the genus level) ascribed to Ascomycota predominated among filamentous fungi, while Basidiomycota dominated among yeasts. At the phylotype level, yeasts dominated the fungal communities: the most frequently found genera were Candida, Glaciozyma, Leucosporidium, Malassezia, Naganishia and Sporobolomyces. The analysis of diversity revealed a high phylogenetic differentiation among samples even at the small-scale level. Salinity, conductivity, pH and the concentration of organic C showed a significant (p < 0.05) impact on the abundance of some fungal genera.
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unfold_moreArctic tundra microbiomes in relation to relative humidity and soil properties
Lotte De Maeyer1; Christophe V.W Seppey2; Bjorn Tytgat1; Mette M. Svenning3; Elie Verleyen1
1Ghent University; 2University of Potsdam; 3UiT The Arctic University of NorwayAbstract:
High-Arctic tundra soils are major carbon reservoirs expected to increasingly impact the global climate through the microbial breakdown of stored organic matter. How environmental factors affect Arctic soil microbiomes remains poorly understood and local conditions may ultimately alter their contributions to climate change. Here we studied surface and subsoil microbial communities along 2 moisture gradients in Kongsfjorden (79° N, Svalbard) using amplicon sequencing targeting Bacteria, Eukarya and Fungi.Relative humidity (RH) was by far the most important factor structuring the surface communities for Bacteria, Eukarya and Fungi and significantly explained 14.2%, 13.9% and 9.0% of the variation in their respective composition. By contrast, in the subsoil communities, soil texture (silt content) was at least equally important as relative humidity in structuring bacterial, eukaryotic and fungal communities, with CN-ratio also co-structuring the former two. A network analysis revealed distinct associations of co-occurring OTUs for both the surface and subsoil communities. We conclude that relative humidity and other abiotic factors have different effects on surface versus subsoil microbial communities in high-Arctic tundra soils. The potential impact of climate change through i.a. shifting moisture availability in these soils may therefore result in contrasting effects between surface and subsoil microbial communities.
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unfold_moreSoil microbial responses to long-term warming experiments in alpine Dryas octopetala heath
Federica D'Alò1; Gabriele Tosadori2; Jana Voriskova2; Silvano Onofri1; Ruben Roos4; Kari Klanderud4
1University of Tuscia; 2Institute of Microbiology of the Czech Academy of Sciences; 3University of Tuscia; 4Norwegian University of Life SciencesAbstract:
During the last century, high altitude and latitude regions on Earth experienced rapid climate warming at rates much higher than other areas. Rising temperatures are causing vegetation changes in alpine and arctic areas, such as shrub encroachment into the tundra, an increase in plant species richness towards mountain summits and higher latitudes, and an increase in the dominance of warm-adapted plant species. These changes may induce changes in plant-associated soil microbial diversity and functioning, as well as on biogeochemical processes, such as nutrient cycling and C fluxes and storage. Open top chambers are warming devices frequently used to improve an increase in air and soil temperature, in order to evaluate the effect of this parameter on both plant and soil communities. Previous research reported that one or two decades of warming are required before pronounced changes in soil parameters occur, while microbial enzyme activity and biomass become visible on a shorter time scale. In this study, we examined how two decades of experimental warming by open top chambers (OTCs) have affected the microbial community structure and function in an alpine Dryas octopetala heath near Finse, in Norway. OTCs passively increase the ambient temperature inside them to simulate future warming scenario; the paired plots outside the OTCs act as control plots, representing the current conditions. Soil from 20 plots (10 OTCs and 10 controls) was collected and analysed for physicochemical properties, microbial biomass, extracellular enzyme activity and by amplicon sequencing of 16S rDNA and ITS region, in order to assess changes in bacterial and fungal community composition and function.
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unfold_moreDiversity and functional genetic potential of polar lake microbiomes
Jill De Visscher1; Bjorn Tytgat1; Elie Verleyen1; Wim Vyverman1; Anne Willems1; Annick Wilmotte2
1Ghent University; 2University of LiègeAbstract:
Benthic microbial communities play key functional roles in polar lake ecosystems. Knowledge of microbiome biodiversity has increased recently, showing strong differences in taxonomic composition between Arctic and (sub)Antarctic regions. However, their genetic functional potential remains poorly understood. Here we applied shotgun metagenomic sequencing to study 17 microbial mat communities in Arctic and (sub)Antarctic lakes.Taxonomy and metabolism were studied with SSU ribosomal and functional genes, respectively. Lakes were typically dominated by Proteobacteria, except in East-Antarctica where Cyanobacteria generally dominate. Bacteroidota are more abundant in deep water habitats in the Transantarctic Mountains lakes, which is likely related to differences in conductivity. Cold stress responsive genes were highly abundant in all lakes. Clear trade-offs between pathways are present in some lakes and are likely related to differences in local environmental conditions. In some East-Antarctic lakes, oxygenic photosynthesis and the Calvin cycle are preferred over other carbon fixation pathways, which is probably due to the dominance of Cyanobacteria. Remineralization genes were found in lakes with catchment vegetation. We conclude that functional differences in polar lake microbial mat communities are mainly related to local conditions, yet that cold stress responsive genes are dominant in each microbial mat. This underlines the specific adaptation of these biota to extreme polar conditions.
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unfold_moreAnimals in cryoconite ecosystem, do they matter?
Krzysztof Zawierucha1, Dariusz Ignatiuk2, Ewa Poniecka3, Elizabeth Bagshaw4, Tereza Novotna-Jaromerska5, Miroslawa Pietryka6, Dorota Richter6, Olena Nahimova1, Piotr Klimaszyk1, Roberto Ambrosini7, Andrea Franzetti8, Artur Trzebny1, Jakub Buda1,
1Adam Mickiewicz University in Poznań; 2University of Silesia in Katowice; 3University of Warsaw; 4Cardiff University; 5Charles University; 6Wrocław University of Environmental and Life Science; 7University of Milan; 8University of Milano-BicoccaAbstract:
Cryoconite is a mixture of mineral and organic matter on the glacier surface. Cryoconite holes are small, water-filled reservoirs in the glacial ice with the layer of cryoconite at their bottom. Due to their simplicity (stable temperature, truncated food webs, few species of grazers), they serve as a natural laboratory for studies of the biogeochemistry and ecology of glacier’s surface. Cryoconite holes are dominated by two groups of invertebrates: tardigrades and rotifers. Although these animals are common worldwide, their role in shaping cryoconite holes ecosystems is poorly known. Using field and laboratory approaches, we tested the effects of tardigrades and rotifers on the biomass of primary producers, organic matter (OM) production, and oxygen concentration in cryoconite holes. Additionally, we investigated the food choice of these apex consumers. In our study, we used stable isotopes (δ13C and δ15N) and metabarcoding (16S rDNA, 18S rDNA and ITS-1) for searching for food sources, microsensors for measurements of oxygen, and Lost on Ignition for measurements of OM. We found that (i) photoautotrophs in cryoconite holes may be controlled by tardigrades, (ii) invertebrates consume a broad range of food in cryoconite, (iii) invertebrates have an impact on the organic matter content in cryoconite, and (iv) animal abundance are related to oxygen conditions in cryoconite holes.