Sensitivity analysis of a King George Island outlet glacier, South Shetlands, Antarctica.

The Lange glacier is an outlet glacier situated in the Admiralty Bay, King George Island, Peninsula Antarctica. It retreated about 1 km since the 1950s. Although recent observations do not show any significant change at the ice-ocean margin, it is not clear whether this glacier has reached a new steady state or whether it is still adjusting to new climate conditions. By combining a three-dimensional glacier model with satellite and in-situ datasets, we investigate the sensitivity of Lange glacier to perturbations in flow rate factor, friction coefficient, surface mass balance, and calving front position. The (time-dependent) perturbation experiments show that the glacier is more sensitive to changes in surface mass balance and in flow rate factor. These results suggest that the climate variability of this region plays an important role on the glacier's dynamics, and that measurements of englacial temperature will improve the reliability of future modeling efforts. Our model shows that the position of the ice front exerts a strong control on the glacier flux. In our time-dependent simulation, the impacts of the observed front retreat on the glacier's dynamics persist beyond the present date. This suggests that Lange is likely still adjusting to past perturbations at its terminus.

Fungi in the Antarctic Cryosphere: Using DNA Metabarcoding to Reveal Fungal Diversity in Glacial Ice from the Antarctic Peninsula Region.

We assessed fungal diversity present in glacial from the Antarctic Peninsula using DNA metabarcoding through high-throughput sequencing (HTS). We detected a total of 353,879 fungal DNA reads, representing 94 genera and 184 taxa, in glacial ice fragments obtained from seven sites in the north-west Antarctic Peninsula and South Shetland Islands. The phylum Ascomycota dominated the sequence diversity, followed by Basidiomycota and Mortierellomycota. Penicillium sp., Cladosporium sp., Penicillium atrovenetum, Epicoccum nigrum, Pseudogymnoascus sp. 1, Pseudogymnoascus sp. 2, Phaeosphaeriaceae sp. and Xylaria grammica were the most dominant taxa, respectively. However, the majority of the fungal diversity comprised taxa of rare and intermediate relative abundance, predominately known mesophilic fungi. High indices of diversity and richness were calculated, along with moderate index of dominance, which varied among the different sampling sites. Only 26 (14%) of the total fungal taxa detected were present at all sampling sites. The identified diversity was dominated by saprophytic taxa, followed by known plant and animal pathogens and a low number of symbiotic fungi. Our data suggest that Antarctic glacial ice may represent a hotspot of previously unreported fungal diversity; however, further studies are required to integrate HTS and culture approaches to confirm viability of the taxa detected.

Statistical modeling of sea ice concentration in the northwest region of the Antarctic Peninsula.

Sea ice is one of the main components of the cryosphere that modifies the exchange of heat and moisture between the ocean and atmosphere, regulating the global climate. In this sense, it is important to identify the concentration of sea ice in different regions of Antarctica in order to measure the impact of environmental changes on the region's ecosystem. The objective of this study was to evaluate the performance of the multiple linear regression and Box-Jenkins methods for predicting the concentration of sea ice along the northwest coast of the Antarctic Peninsula. Sea ice concentration data from May to November for the period 1979-2018 were extracted from passive remote sensors including a scanning multichannel microwave radiometer, special sensor microwave imager, and special sensor microwave imager/sounder. Meteorological variables from the atmospheric reanalysis model ERA5 of the European Center for Medium-Range Weather Forecasts were used as predictor variables, and the leave-one-out cross-validation technique was used to calibrate and validate the models. It was found that both statistical models have similar performance when analyzing residual analysis results, root mean square error of cross-validation, and final accuracy and residual standard deviation, these responses being related to the regionalization of the study area and to the Box-Jenkins presents strong, homogeneous, and stable correlations in the time series modeled for each pixel.

Fungi in glacial ice of Antarctica: diversity, distribution and bioprospecting of bioactive compounds.

We identified cultivable fungi present in the glacial ice fragments collected in nine sites across Antarctica Peninsula and assessed their abilities to produce bioactive compounds. Three ice fragments with approximately 20 kg were collected, melted and 3 L filtered through of 0.45 µm sterilized membranes, which were placed on the media Sabouraud agar and minimal medium incubated at 10 °C. We collected 66 isolates classified into 27 taxa of 14 genera. Penicillium palitans, Penicillium sp. 1, Thelebolus balaustiformis, Glaciozyma antarctica, Penicillium sp. 7, Rhodotorula mucilaginosa, and Rhodotorula dairenensis had the highest frequencies. The diversity and richness of the fungal community were high with moderate dominance. Penicillium species were present in all samples, with Penicillium chrysogenum showing the broadest distribution. P. chrysogenum, P. palitans, and Penicillium spp. had trypanocidal, leishmanicidal, and herbicidal activities, with P. chrysogenum having the broadest and highest capability. 1H NMR signals revealed the presence of highly functionalized secondary metabolites in the bioactive extracts. Despite extreme environmental conditions, glacial ice harbours a diverse fungal community, including species never before recorded in the Arctic and Antarctica. Among them, Penicillium taxa may represent wild fungal strains with genetic and biochemical pathways that may produce new secondary bioactive metabolites.

Functional diversity of microbial communities in soils in the vicinity of Wanda Glacier, Antarctic Peninsula.

Microbial functional diversity in four soils sampled in the vicinity of Wanda Glacier, Antarctic Peninsula, was determined using Biolog EcoPlates at 5°C and 25°C. Comparisons of the patterns of substrate utilization and the diversity index showed differences in community composition, reflecting the heterogeneous distribution of microorganisms in this environment. Differences in microbial diversity may be related to soil chemical properties. Higher incubation temperature influenced the overall microbial diversity, reducing richness due to the selection of psychrotrophic microorganisms. To our knowledge, this is the first study with microbial communities from Wanda Glacier and contributes to understanding the microbial diversity of Antarctic environments.