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The occurrence of mycothalli, symbioses between liverworts and fungi bearing similarities to mycorrhizas, is poorly documented in sub-Antarctica, and biogeographical patterns in Serendipita, one of the main fungal genera forming the symbiosis, remain understudied. Here, 83 specimens of 16 leafy liverwort species in eight families were hence sampled from 12 sites on the Thatcher Peninsula on sub-Antarctic South Georgia and were examined for mycothalli. Staining and epifluorescence microscopy were used to enumerate fungal structures in liverwort tissues, and PCR amplification and sequencing of fungal ribosomal DNA were used to determine the taxonomic and biogeographical affinities of the fungi present in plants. Stained hyphal coils, a defining feature of the symbiosis, were found to be frequent (>40 % of stem length colonised) in Barbilophozia hatcheri (Anastrophyllaceae), Cephaloziella varians (Cephaloziellaceae) and Lophoziopsis excisa (Lophoziaceae). Analyses of fungal ITS2 region sequences showed that a single species of Serendipita, based on a 3 % cut-off for sequence divergence, was a frequent colonist of B. hatcheri, C. varians and L. excisa, and that a further 18 basidiomycete and ascomycete taxa colonised other liverwort species. Principal component analysis and analysis of variance indicated that the presence of the Serendipita species was positively associated with the occurrence of stained hyphal coils in stem epidermal cells. Phylogenetic analyses, incorporating worldwide accessions from leafy liverwort-associated Serendipita, showed that the same species, which also occurs in Chile, mainland Europe and on Svalbard, is apparently the sole symbiont of sub- and maritime Antarctic leafy liverworts, and indicated much higher species richness of the genus outside Antarctica.

For more than five decades, research has been conducted at Ny-Ålesund, in Svalbard, Norway, to understand the structure and functioning of High-Arctic ecosystems and the profound impacts on them of environmental change. Terrestrial, freshwater, glacial and marine ecosystems are accessible year-round from Ny-Ålesund, providing unique opportunities for interdisciplinary observational and experimental studies along physical, chemical, hydrological and climatic gradients. Here, we synthesize terrestrial and freshwater research at Ny-Ålesund and review current knowledge of biodiversity patterns, species population dynamics and interactions, ecosystem processes, biogeochemical cycles and anthropogenic impacts. There is now strong evidence of past and ongoing biotic changes caused by climate change, including negative effects on populations of many taxa and impacts of rain-on-snow events across multiple trophic levels. While species-level characteristics and responses are well understood for macro-organisms, major knowledge gaps exist for microbes, invertebrates and ecosystem-level processes. In order to fill current knowledge gaps, we recommend (1) maintaining monitoring efforts, while establishing a long-term ecosystem-based monitoring programme; (2) gaining a mechanistic understanding of environmental change impacts on processes and linkages in food webs; (3) identifying trophic interactions and cascades across ecosystems; and (4) integrating long-term data on microbial, invertebrate and freshwater communities, along with measurements of carbon and nutrient fluxes among soils, atmosphere, freshwaters and the marine environment. The synthesis here shows that the Ny-Ålesund study system has the characteristics needed to fill these gaps in knowledge, thereby enhancing our understanding of High-Arctic ecosystems and their responses to environmental variability and change.

Mineral extraction is known to affect soil fungi in polar environments, but it is unknown how long these effects persist. Here, by amplifying the internal transcribed spacer regions of rRNA genes in soil fungi, we compared soil fungal community in intact natural tundra with that in a nearby former coal mining area, abandoned 52 years previously, on Svalbard in the High Arctic. Compared with those in intact tundra, soils in the former mining area were more acidic and had lower plant coverage. Despite of similar diversity in the two areas, the fungal community was dominated by Basidiomycota in the intact tundra, but by Ascomycota in the former mining area. Ectomycorrhizal genera formed a major part of the tundra community, but were notably less abundant in the mining area. The principal variation among samples was soil pH. Surprisingly, network connectivity analysis indicated that the fungal community in the former mining area had greater network connectivity than that in the tundra area. Overall, the ecosystem in the former mining area has made only limited recovery towards the natural tundra state even after more than five decades. It is unclear whether the recovery of the fungal community is limited more by the low primary productivity, slow migration of fungi and plants, or slow changes in soil parameters. Our findings emphasize the susceptibility of polar ecosystems to disturbance, given their particularly slow recovery back towards the natural state. © 2022 Soil Science Society of China.

Previous studies have shown changes to the frequencies of hyphal coils and other fungal structures in leafy liverwort tissues across latitudinal transects through Antarctica. Although suggestive of a role of temperature in determining the frequencies of fungal structures, these studies could not exclude the possibility that other factors which alter at lower latitudes—notably liquid water availability—were responsible for the observed patterns of fungal colonisation. Here, in a field experiment in maritime Antarctica, the effects of warming with open top chambers (OTCs) on the frequencies of fungal structures in the leafy liverwort Cephaloziella varians were determined. At five samplings of the experiment taking place 5–10 years after its deployment, OTCs, which increased the summertime temperature of C. varians mats by 1.1 °C, but had no measurable effects on mat moisture concentration, were found to double the frequencies of fine hyphal coils in liverwort tissues. Over the duration of the experiment, the OTCs also significantly increased the frequency of rhizoids on C. varians stems, but had no effects on the frequencies of coarse hyphal coils, dark septate hyphae, hyaline septate hyphae, or hyphal colonisation of rhizoids. Given that C. varians can be recovered from frozen peatbank cores, it is proposed that the abundance of fine hyphal coils in its tissues might be used as a signal of recent climate warming on the Antarctic Peninsula.

BackgroundThe emergence of antibiotic-resistant pathogens has created an urgent need for novel antimicrobial treatments. Advances in next-generation sequencing have opened new frontiers for discovery programmes for natural products allowing the exploitation of a larger fraction of the microbial community. Polyketide (PK) and non-ribosomal pepetide (NRP) natural products have been reported to be related to compounds with antimicrobial and anticancer activities. We report here a new culture-independent approach to explore bacterial biosynthetic diversity and determine bacterial phyla in the microbial community associated with PK and NRP diversity in selected soils.ResultsThrough amplicon sequencing, we explored the microbial diversity (16S rRNA gene) of 13 soils from Antarctica, Africa, Europe and a Caribbean island and correlated this with the amplicon diversity of the adenylation (A) and ketosynthase (KS) domains within functional genes coding for non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), which are involved in the production of NRP and PK, respectively. Mantel and Procrustes correlation analyses with microbial taxonomic data identified not only the well-studied phyla Actinobacteria and Proteobacteria, but also, interestingly, the less biotechnologically exploited phyla Verrucomicrobia and Bacteroidetes, as potential sources harbouring diverse A and KS domains. Some soils, notably that from Antarctica, provided evidence of endemic diversity, whilst others, such as those from Europe, clustered together. In particular, the majority of the domain reads from Antarctica remained unmatched to known sequences suggesting they could encode enzymes for potentially novel PK and NRP.ConclusionsThe approach presented here highlights potential sources of metabolic novelty in the environment which will be a useful precursor to metagenomic biosynthetic gene cluster mining for PKs and NRPs which could provide leads for new antimicrobial metabolites.

Soil microbial communities in the Arctic, one of the most rapidly warming regions on Earth, play an important role in a range of ecological processes. This report describes initial studies of natural soil bacterial diversity at a High Arctic site on Svalbard, as part of a long-term field environmental manipulation study. The impact of increased soil temperature and water availability on soil microbial communities was investigated. The manipulation experiment, using open-top chambers, was installed in late summer 2014, and the soils were sampled soon after snow melt in July 2015. High throughput sequencing of 16S rRNA genes showed relatively uniform diversity across the study area and revealed no significant initial effect of treatments on bacterial communities over the first 10-month autumn–winter–spring manipulation period.