Search Results (3)

Byers Peninsula is considered one of the largest ice-free areas in maritime Antarctica. Since 2006, the Spanish Polar Program has taken part in a large number of environmental studies involving the effects of climate change on biological life cycles, limnology, and microbiology. Soils from maritime Antarctica are generally weakly developed and have chemical, physical, and morphological characteristics that are strongly influenced by the parent material. However, biological activity during the short Antarctic summer promotes intense transference of nutrients and organic matter in areas occupied by different species of birds and marine mammals. Mapping and monitoring those areas that are highly occupied by various species could be very useful to create models prepared from satellite images of the edaphic properties. In this approach, deep learning and linear regression models of the soil properties and spectral indexes, which were considered as explicative variables, were used. We trained the models on soil properties closely related to biological activity such as dissolved organic carbon (DOC) and the iron fraction associated with the organic matter (Fe). We tested the best approach to model the spatial distribution of DOC, Fe, and pH by training the linear regression and deep learning models on Sentinel-2 and WorldView-2 images. The most robust models, the pH model built with the deep learning approach on Sentinel images (MAE of 0.51, RMSE of 0.70, and R2 with a residual of −0.49), the DOC model built with linear regression on Sentinel images (MAE of 189.39, RMSE of 342.23, and R2 with a residual of 0.0), and the organic Fe model built with deep learning (MAE of 116.20, RMSE of 209.93, and R2 of −0.05), were used to track possible areas with ornithogenic soils, as well as areas of Byers Peninsula that could be supporting the highest biological development. Full article

A summer survey was conducted on the bacterioplankton communities of seven lakes from Byers Peninsula (Maritime Antarctica), differing in trophic and morphological characteristics. Predictions of the metabolic capabilities of these communities were performed with FAPROTAX using 16S rRNA sequencing data. The versatility for metabolizing carbon sources was also assessed in three of the lakes using Biolog Ecoplates. Relevant differences among lakes and within lake depths were observed. A total of 23 metabolic activities associated to the main biogeochemical cycles were foreseen, namely, carbon (11), nitrogen (4), sulfur (5), iron (2), and hydrogen (1). The aerobic metabolisms dominated, although anaerobic respiration was also relevant near the lakes’ bottom as well as in shallow eutrophic lakes with higher nutrient and organic matter contents. Capacity for using carbon sources further than those derived from the fresh autochthonous primary production was detected. Clustering of the lakes based on metabolic capabilities of their microbial communities was determined by their trophic status, with functional diversity increasing with trophic status. Data were also examined using a co-occurrence network approach, indicating that the lakes and their catchments have to be perceived as connected and interacting macrosystems, where either stochastic or deterministic mechanisms for the assembling of communities may occur depending on the lake’s isolation. The hydrological processes within catchments and the potential metabolic plasticity of these biological communities must be considered for future climate scenarios in the region, which may extend the growing season and increase biomass circulation. Full article

Here we present a comprehensive review of the diversity revealed by research in limnology and microbial ecology conducted in Byers Peninsula (Livingston Island, South Shetland Islands, Antarctica) during the last two decades. The site constitutes one of the largest ice-free areas within the Antarctic Peninsula region. Since it has a high level of environmental protection, it is less human-impacted compared to other sites within the South Shetland archipelago. The main investigations in Byers Peninsula focused on the physical and chemical limnology of the lakes, ponds, rivers, and wetlands, as well as on the structure of their planktonic and benthic microbial communities, and on the functional ecology of the microbial food webs. Lakes and ponds in Byers range along a productivity gradient that extends from the less productive lakes located upland to the eutrophic coastal lakes. Their planktonic assemblages include viruses, bacteria, a metabolically diverse community of protists (i.e., autotrophs, heterotrophs, and mixotrophs), and a few metazooplankton species. Most of the studies conducted in the site demonstrate the strong influence of the physical environment (i.e., temperature, availability of light, and water) and nutrient availability in structuring these microbial communities. However, top-down biotic processes may occur in summer, when predation by zooplankton can exert a strong influence on the abundance of protists, including flagellates and ciliated protozoa. As a consequence, bacterioplankton could be partly released from the grazing pressure exerted by these protists, and proliferates fueled by external nutrient subsidies from the lake’s catchment. As summer temperatures in this region are slightly above the melting point of water, biotic processes, such as those related to the productivity of lakes during ice-free periods, could become even more relevant as warming induced by climate change progresses. The limnological research carried out at the site proves that Byers Peninsula deserves special attention in the framework of the research in extreme environments. Together with nearby sites, such as Signy Island, Byers Peninsula comprises a featuring element of the Maritime Antarctic region that represents a benchmark area relative to the global distribution and diversity of aquatic microorganisms. Full article