Deception Island Research Articles

Biotechnological potential in agriculture of soil Antarctic microorganisms revealed by omics approach.

The biotechnological potential for agricultural applications in the soil in the thawing process on Whalers Bay, Deception Island, Antarctica was evaluated using a metagenomic approach through high-throughput sequencing. Approximately 22.70% of the sequences were affiliated to the phyla of the Bacteria dominion, followed by 0.26% to the Eukarya. Proteobacteria (Bacteria) and Ascomycota (Fungi) were the most abundant phyla. Thirty-two and thirty-six bacterial and fungal genera associated with agricultural biotechnological applications were observed. Streptomyces and Pythium were the most abundant genera related to the Bacteria and Oomycota, respectively. The main agricultural application associated with bacteria was nitrogen affixation; in contrast for fungi, was associated with phytopathogenic capabilities. The present study showed the need to use metagenomic technology to understand the dynamics and possible metabolic pathways associated with the microbial communities present in the soil sample in the process of thawing recovered from the Antarctic continent, which presented potential application in processes of agro-industrial interest.

Marine microbial community taxonomic and functional indicators to volcanic and anthropogenic stressors in Deception Island, Antarctica

In recent years, the growth in Antarctic tourism has stimulated research on the anthropogenic impacts on the region, boosted by advances in OMIC technologies applied to polar microbial communities. This study aimed to assess the human impacts on marine prokaryotic and viral communities of Deception Island by identifying potential taxonomic, functional, and resistome indicators of both anthropogenic and natural/volcanic pressures. Proteobacteria, Bacteroidetes, and Actinobacteria were the dominant phyla, with notable variations attributed to volcanic activity and anthropogenic pressure. The abundance of Euryarchaeota in regions with increased volcanic activity underlines their adaptability to extreme conditions. Their mercury resistance coupled with their ability to cope with toxic heavy metals is a critical component in managing volcanic mercury concentrations. Actinobacteria, Cyanobacteria, Planctomycetes, and Synergistetes showed distinctive abundance patterns with potential ecological implications related to volcanic environments. Functional analyses revealed the enrichment of functions associated with metal-based, hydrocarbon degradation, and nitrogen metabolism. Submarine volcanic vents contributed significantly to the shape of functional diversity. Identification of specific functions related to nosocomial infections and gastroenteritis highlights the impact of anthropogenic activities on functional traits. Antibiotic resistance genes (ARGs) showed nuanced patterns influenced by both anthropogenic pressure and volcanic activity. Actinobacteria were correlated with increased ARG abundance, which was enhanced by wastewater disposal. Remarkably, Fumarole Bay showed an increased prevalence of certain ARGs, despite a lower anthropogenic impact, suggesting a unique selective pressure induced by volcanic activity. The responsiveness of these indicators to varying levels of pressure characterizes them as valuable tools for assessing and mitigating anthropogenic impacts on the marine waters of Deception Island.

Employing automated electrical resistivity tomography for detecting short- and long-term changes in permafrost and active-layer dynamics in the maritime Antarctic

Abstract. Repeated electrical resistivity tomography (ERT) surveys can substantially advance the understanding of spatial and temporal freeze–thaw dynamics in remote regions, such as Antarctica, where the evolution of permafrost has been poorly investigated. To enable time-lapse ERT surveys in Antarctica, an automated ERT (A-ERT) system is required, as regular site visits are not feasible. In this context, we developed a robust A-ERT prototype and installed it at the Crater Lake CALM-S site on Deception Island, Antarctica, to collect quasi-continuous ERT measurements. We developed an automated data processing workflow to efficiently filter and invert the A-ERT datasets and extract the key information required for a detailed investigation of permafrost and active-layer dynamics. In this paper, we report on the results of two complete year-round A-ERT datasets collected in 2010 and 2019 at the Crater Lake CALM-S site and compare them with available climate and borehole data. The A-ERT profile has a length of 9.5 m with an electrode spacing of 0.5 m, enabling a maximum investigation depth of approximately 2 m. Our detailed investigation of the A-ERT data and inverted results shows that the A-ERT system can detect the active-layer freezing and thawing events with high temporal resolution. The resistivity of the permafrost zone in 2019 is very similar to the values found in 2010, suggesting the stability of the permafrost over almost 1 decade at this site. The evolution of thaw depth exhibits a similar pattern in both years, with the active-layer thickness fluctuating between 0.20–0.35 m. However, a slight thinning of the active layer is evident in early 2019, compared to the equivalent period in 2010. These findings show that A-ERT datasets, combined with the new processing workflow that we developed, are an effective tool for studying permafrost and active-layer dynamics with very high resolution and minimal environmental disturbance. The ability of the A-ERT setup to monitor the spatiotemporal progression of thaw depth in two dimensions, and potentially in three dimensions, and to detect brief surficial refreezing and thawing of the active layer reveals the significance of the automatic ERT monitoring system to record continuous resistivity changes. An A-ERT monitoring setup with a longer profile length can investigate greater depths, offering effective monitoring at sites where boreholes are costly and invasive techniques are unsuitable. This shows that the A-ERT setup described in this paper can be a significant addition to the Global Terrestrial Network for Permafrost (GTN-P) and the Circumpolar Active Layer Monitoring (CALM) networks to further investigate the impact of fast-changing climate and extreme meteorological events on the upper soil horizons and to work towards establishing an early warning system for the consequences of climate change.

Hydrothermal alteration of seawater biogeochemistry in Deception Island (South Shetland Islands, Antarctica)

Hydrothermal alteration of seawater biogeochemistry in Deception Island (South Shetland Islands, Antarctica)

Antarctic Spore-Forming Microorganisms from Deception Island Inhibit the Growth of Various Bacterial Strains

Antarctic microbes have evolved and adapted unique strategies to survive in the harsh polar environment. Apart from the ability to adapt to the low nutrient soil content and extremely dry and cold polar environment, a particular strategy used by Antarctic bacteria is the production of antimicrobial compounds that can eliminate rivals in the same niche, giving them a competitive edge over other microbes. In contrast, it is unclear whether spore-forming microbes possess similar antimicrobial properties as one of their survival strategies, especially those from the Antarctic volcanic Deception island in the West Antarctic. Hence, this study aims to isolate and characterize the spore-forming microbes in Deception Island, Antarctica, as well as to identify the ones that are equipped with the ability to inhibit other microorganisms. Microbes were isolated using various growth media and were segregated into clusters based on their random amplified polymorphic DNA (RAPD) fingerprints. A total of 90 strains were isolated and clustered into 30 groups at a similarity of 60%. Representative strains from each cluster were assayed for antimicrobial activities against 13 Gram-positive and Gram-negative test bacteria comprising human pathogens. Twenty-five strains exhibited the ability to inhibit at least one test bacterium. The four strains, A60, Im31, Im32 and Im33 that showed the strongest inhibitory activities were subjected to 16S or 18S rDNA sequencing and analysis to identify them. They were identified as Pseudogymnoascus, Bacillus, Leohumicola, and Talaromyces spp. The ability of the aforementioned microbes to thrive in harsh environments and compete with fierce competitors for scarce nutrients is probably due to their ability to produce antimicrobial compounds that target and kill their rivals.

Recombinant Expression and Characterization of a Novel Thermo-Alkaline Lipase with Increased Solvent Stability from the Antarctic Thermophilic Bacterium Geobacillus sp. ID17.

Lipases are enzymes that hydrolyze long-chain carboxylic esters, and in the presence of organic solvents, they catalyze organic synthesis reactions. However, the use of solvents in these processes often results in enzyme denaturation, leading to a reduction in enzymatic activity. Consequently, there is significant interest in identifying new lipases that are resistant to denaturing conditions, with extremozymes emerging as promising candidates for this purpose. Lip7, a lipase from Geobacillus sp. ID17, a thermophilic microorganism isolated from Deception Island, Antarctica, was recombinantly expressed in E. coli C41 (DE3) in functional soluble form. Its purification was achieved with 96% purity and 23% yield. Enzymatic characterization revealed Lip7 to be a thermo-alkaline enzyme, reaching a maximum rate of 3350 U mg-1 at 50 °C and pH 11.0, using p-nitrophenyl laurate substrate. Notably, its kinetics displayed a sigmoidal behavior, with a higher kinetic efficiency (kcat/Km) for substrates of 12-carbon atom chain. In terms of thermal stability, Lip7 demonstrates stability up to 60 °C at pH 8.0 and up to 50 °C at pH 11.0. Remarkably, it showed high stability in the presence of organic solvents, and under certain conditions even exhibited enzymatic activation, reaching up to 2.5-fold and 1.35-fold after incubation in 50% v/v ethanol and 70% v/v isopropanol, respectively. Lip7 represents one of the first lipases from the bacterial subfamily I.5 and genus Geobacillus with activity and stability at pH 11.0. Its compatibility with organic solvents makes it a compelling candidate for future research in biocatalysis and various biotechnological applications.

Experimental and computational investigation of passive heat exchangers to enhance the performance of a geothermal thermoelectric generator

Thermoelectric devices hold significant promise for generating electricity from geothermal heat, enabling the powering of measuring equipment in remote locations without the need for moving parts. Nevertheless, most developed geothermal thermoelectric generators employ fans and pumps to enhance heat transfer, thereby compromising the robustness and reliability inherent to thermoelectricity. Furthermore, there is a lack of research on passive heat exchangers for geothermal thermoelectric generators, particularly in studying their operation under a wide range of meteorological conditions. Therefore, this paper conducts a comprehensive analysis of passive heat exchangers for the cold side of the generators. Phase-change-based heat exchangers differing in their length and fluid are studied experimentally, along with a fin dissipator. Additionally, the influence of wind velocity on heat transfer and mechanical requirements is further explored through a Computational Fluid Dynamics model. The most significant outcome is quantifying the impact of the design parameters and operational variables on the electrical production of the thermoelectric generator. Accordingly, this research aims to broaden the application of these generators to extreme environments, such as Deception Island in Antarctica. Under average operational conditions, generators incorporating 400mm water heat pipes generate 0.95W per thermoelectric module, while those incorporating heat pipes with methanol achieve an average of 0.70W. Moreover, water and methanol-based systems produce 120% and 60% more power than generators using a fin dissipator. Nonetheless, for temperatures beyond -6.5°C, water might freeze and the methanol-based heat exchangers become more suitable.

Unlocking the biosynthetic potential and taxonomy of the Antarctic microbiome along temporal and spatial gradients.

Extreme environments, such as Antarctica, select microbial communities that display a range of evolutionary strategies to survive and thrive under harsh environmental conditions. These include a diversity of specialized metabolites, which have the potential to be a source for new natural product discovery. Efforts using (meta)genome mining approaches to identify and understand biosynthetic gene clusters in Antarctica are still scarce, and the extent of their diversity and distribution patterns in the environment have yet to be discovered. Herein, we investigated the biosynthetic gene diversity of the biofilm microbial community of Whalers Bay, Deception Island, in the Antarctic Peninsula and revealed its distribution patterns along spatial and temporal gradients by applying metagenome mining approaches and multivariable analysis. The results showed that the Whalers Bay microbial community harbors a great diversity of biosynthetic gene clusters distributed into seven classes, with terpene being the most abundant. The phyla Proteobacteria and Bacteroidota were the most abundant in the microbial community and contributed significantly to the biosynthetic gene abundances in Whalers Bay. Furthermore, the results highlighted a significant correlation between the distribution of biosynthetic genes and taxonomic diversity, emphasizing the intricate interplay between microbial taxonomy and their potential for specialized metabolite production.IMPORTANCEThis research on antarctic microbial biosynthetic diversity in Whalers Bay, Deception Island, unveils the hidden potential of extreme environments for natural product discovery. By employing metagenomic techniques, the research highlights the extensive diversity of biosynthetic gene clusters and identifies key microbial phyla, Proteobacteria and Bacteroidota, as significant contributors. The correlation between taxonomic diversity and biosynthetic gene distribution underscores the intricate interplay governing specialized metabolite production. These findings are crucial for understanding microbial adaptation in extreme environments and hold significant implications for bioprospecting initiatives. The study opens avenues for discovering novel bioactive compounds with potential applications in medicine and industry, emphasizing the importance of preserving and exploring these polyextreme ecosystems to advance biotechnological and pharmaceutical research.

Fine-scale phylogenetic diversity gradients support the Antarctic geothermal refugia hypothesis

Abstract The possible role of geothermal areas, such as volcanoes, in fostering biodiversity in Antarctica has received considerable recent attention. Under a geothermal refugia hypothesis, diverse life could be supported near or at geothermal sites, and we should see decreasing diversity and/or patterns of nestedness moving away from ‘hotspots’. Although there is evidence that geothermal areas have played a role in the persistence of some terrestrial species through glacial periods in Antarctica, the spatial scales at which such refugia operate is not clear. We sampled sediment from a range of locations across volcanic Deception Island in the Maritime Antarctic and used eDNA metabarcoding approaches (targeting a region of the 28S marker) to assess patterns of diversity in relation to thermal gradients. We found that although colder sites harboured significantly greater taxonomic richness than warmer sites, phylogenetic diversity was lower at colder sites (i.e. taxa at colder sites tend to be more evolutionary close to each other). We infer that increased selective processes in low-temperature environments have reduced phylogenetic diversity, supporting a hypothesis of geothermal locations acting as refugia for diverse taxa, even on fine spatial scales, in cold-climate regions such as Antarctica.

Soil cover shapes organic matter pools and microbial communities in soils of maritime Antarctica

Bryophytes and biological soil crusts (biocrusts) are the two major biological soil cover types of maritime Antarctica and play a crucial role for key ecosystem functions in the barely vegetated and little developed soils. Besides their profound impacts on nutrient cycling, they also provide habitats and activity hotspots for unique soil microbial communities. Yet, the effects of biological soil cover on the physical and chemical soil environment and belowground microbial communities have not been comprehensively studied in this fragile ecosystem.We here address the research question how biocrusts and mosses shape the quantity and structure of the soil organic matter pool, and the activity and composition of subjacent microbial communities. Towards this end, we sampled soils under two common, but physiologically distinct moss species, Polytrichastrum alpinum and Sanionia unicinata, and adjacent biological soil crusts at two sites on Deception Island, South Shetland Islands.We found that biocrusts and mosses differentially influenced central soil properties and subjacent soil microbial communities. All major SOM compound groups (carbohydrates, aromatics and phenols, lipids, N-containing polymers) as well as microbial biomass were more abundant in soil under biocrusts. However, microbial mass-specific growth rates were higher in soil under mosses. Our results showed moss-species-specific effects in addition to effects of soil cover type, as P. alpinum affected the activity and structure of soil microbial communities and the composition of soil organic matter stronger than S. unicinata.Our study highlights the interconnectedness between soil cover and soil biogeochemistry, which is crucial for deepening our understanding of belowground functioning in Antarctic soils. This linkage is of particular importance in the context of ongoing rapid climate change on the Antarctic Peninsula, as future shifts in the distribution and abundance of soil cover may substantially impact multiple soil processes in this vulnerable ecosystem.

Antarctic marine sediment as a source of filamentous fungi-derived antimicrobial and antitumor compounds of pharmaceutical interest.

Antarctica harbors a microbial diversity still poorly explored and of inestimable biotechnological value. Cold-adapted microorganisms can produce a diverse range of metabolites stable at low temperatures, making these compounds industrially interesting for biotechnological use. The present work investigated the biotechnological potential for antimicrobial and antitumor activity of filamentous fungi and bacteria isolated from marine sediment samples collected at Deception Island, Antarctica. A total of 89 microbial isolates were recovered from marine sediments and submitted to an initial screening for L-glutaminase with antitumoral activity and for antimicrobial metabolites. The isolates Pseudogymnoascus sp. FDG01, Pseudogymnoascus sp. FDG02, and Penicillium sp. FAD33 showed potential antiproliferative action against human pancreatic carcinoma cells while showing no toxic effect on non-tumor cells. The microbial extracts from unidentified three bacteria and four filamentous fungi showed antibacterial activity against at least one tested pathogenic bacterial strain. The isolate FDG01 inhibited four bacterial species, while the isolate FDG01 was active against Micrococcus luteus in the minimal inhibitory concentration of 0.015625μgmL-1. The results pave the way for further optimization of enzyme production and characterization of enzymes and metabolites found and reaffirm Antarctic marine environments as a wealthy source of compounds potentially applicable in the healthcare and pharmaceutical industry.

Improvements in the Estimation of Air Temperature with Empirical Models on Livingston and Deception Islands in Maritime Antarctica (2000–2016) Using C6 MODIS LST

Temperature analysis is of special interest in polar areas because temperature is an essential variable in the energy exchange between the Earth’s surface and atmosphere. Although land surface temperature (LST) obtained using satellites and air temperature (Ta) have different physical meanings and are measured with different techniques, LST has often been successfully employed to estimate Ta. For this reason, in this work, we estimated Ta from LST MODIS collection 6 (C6) and used other predictor variables. Daily mean Ta was calculated from Spanish State Meteorological Agency (AEMET) stations data on the Livingston and Deception Islands, and from the PERMASNOW project stations on Livingston Island; both islands being part of the South Shetland Islands (SSI) archipelago. In relation to our previous work carried out in the study area with collection 5 (C5) data, we obtained higher R2 values (R2CV = 0.8, in the unique model with Terra daytime data) and lower errors (RMSECV = 2.2 °C, MAECV = 1.6 °C). We corroborated significant improvements in MODIS C6 LST data. We analyzed emissivity as a possible factor of discrepancies between C5 and C6, but we did not find conclusive results, therefore we could not affirm that emissivity is the factor that causes differences between one collection and another. The results obtained with the applied filters indicated that MODIS data can be used to study Ta in the area, as these filters contribute to the reduction of uncertainties in the modeling of Ta from satellites.

New approaches and error assessment to snow cover thickness and density using air temperature data at different heights

Snow poles are inexpensive systems composed of a wooden mast with temperature sensors affixed at varying heights with the purpose of estimating the snow depth. They are frequently utilised in cold, remote regions where the maintenance of complex monitoring instruments becomes impractical. In this study, snow cover thickness is determined using different methods, based on the thermal behaviour of air temperature measured by a snow pole on Deception Island, Antarctica. The methods are compared to high-resolution measurements of snow depth obtained using an ultrasonic sensor at the same site. A new modified method is proposed and shown to give the best results. Errors and sensitivity to chosen thresholds of the various methods have been compared. Sensitivity tests have been also conducted to evaluate the impact of missing data from some of the sensors. Finally, the insulating effect on the thermal signal produced by the snow is used to obtain information on the snowpack density. Promising results have been found from this effort, opening new possibilities for the usage of snow poles and may lead to future studies.

Assessing aerial biodiversity over Keller Peninsula, King George Island, Maritime Antarctica, using DNA metabarcoding

Abstract Antarctic ice-free areas are dominated by wind-dispersed organisms. However, which organisms arrive and circulate in Antarctica and how remain poorly understood. Due to their proximity to South America and less extreme conditions, the South Shetland Islands are likely to receive higher diaspore numbers. One possible consequence of climate change is that newcomers will be able to colonize ice-free areas, altering community compositions and impacting the native biota. We used DNA metabarcoding to identify non-fungal eukaryotic DNA present in the air that could potentially reach and circulate in Antarctica. Air was sampled near the Brazilian Comandante Ferraz Antarctic Station on King George Island between December 2019 and January 2020. Sequences representing a total of 35 taxa from 10 phyla and 3 kingdoms were assigned: Chromista (Ciliophora, Cercozoa, Haptophyta and Ochrophyta), Plantae (Chlorophyta, Bryophyta and Magnoliophyta) and Animalia (Mollusca, Arthropoda and Chordata). The most diverse group were the plants (26 taxa), followed by Chromista (6 taxa). The most abundant sequences represented the green algae Chlamydomonas nivalis. The two angiosperm sequences represent exotic taxa; Folsomia is also exotic and was recorded only on Deception Island. Metabarcoding revealed the presence of previously undocumented airborne diversity, suggesting that the Antarctic airspora includes propagules of both local and distant origin.

Spatiotemporal Evolution of the Land Cover over Deception Island, Antarctica, Its Driving Mechanisms, and Its Impact on the Shortwave Albedo

The aim of this work is to provide a full description of how air temperature and solar radiation induce changes in the land cover over an Antarctic site. We use shortwave broadband albedo (albedo integrated in the range 300–3000 nm) from a spaceborne sensor and from field surveys to calculate the monthly relative abundance of landscape units. Field albedo data were collected in January 2019 using a portable albedometer over seven landscape units: clean fresh snow; clean old snow; rugged landscape composed of dirty snow with disperse pyroclasts and rocky outcrops; dirty snow; stripes of bare soil and snow; shallow snow with small bare soil patches; and bare soil. The MODIS MCD43A3 daily albedo products were downloaded using the Google Earth Engine API from the 2000–2001 season to the 2020–2021 season. Each landscape unit was characterized by an albedo normal distribution. The monthly relative abundances of the landscape units were calculated by fitting a linear combination of the normal distributions to a histogram of the MODIS monthly mean albedo. The monthly relative abundance of the landscape unit consisting of rugged landscape composed of dirty snow with dispersed clasts and small rocky outcrops exhibits a high positive linear correlation with the monthly mean albedo (R2 = 0.87) and a high negative linear correlation with the monthly mean air temperature (R2 = 0.69). The increase in the solar radiation energy flux from September to December coincides with the decrease in the relative abundance of the landscape unit composed of dirty snow with dispersed clasts and small rocky outcrops. We propose a mechanism to describe the evolution of the landscape: uncovered pyroclasts act as melting centers favoring the melting of surrounding snow. Ash does not play a decisive role in the melting of the snow. The results also explain the observed decrease in the thaw depth of the permafrost on the island in the period 2006–2014, resulting from an increase in the snow cover over the whole island.

Astrobiological implications of the organic and inorganic cyanide utilization by a novel Antarctic hyperthermophilic Pyrococcus strain.

Organic and inorganic cyanides are widely distributed in nature, yet not much is known about the ability of microorganisms to use these compounds as a source of nitrogen and/or carbon at high temperatures (>80°C). Here we studied the capacity of organic and inorganic cyanides to support growth of an hyperthermophilic Pyrococcus strain isolated from Deception Island, Antarctica. This microorganism was capable of growing with aromatic nitriles, aliphatic nitriles, heterocyclic nitriles, amino aromatic nitriles and inorganic cyanides as nitrogen and/or carbon source. This is the first report of an hyperthermophilic microorganism able to incorporate these compounds in its nitrogen and carbon metabolism. Based on enzymatic activity and genomic information, it is possibly that cells of this Pyrococcus strain growing with nitriles or cyanide, might use the carboxylic acid and/or the ammonia generated through the nitrilase enzymatic activity, as a carbon and/or nitrogen source respectively. This work expands the temperature range at which microorganisms can use organic and inorganic cyanides to growth, having important implications to understand microbial metabolisms that can support life on Earth and the possibility to support life elsewhere.

Energy characterization of buildings in polar climate: Case study of Gabriel de Castilla Antarctic station

In this paper, we present the energy characterization of two habitable modules at the Spanish station “Gabriel de Castilla”, located on Deception Island, Antarctica. The analysis includes profiles of energy consumption for space heating and domestic hot water, as well as indoor air conditions, which were all recorded during one month of Antarctic summer. Additionally, the measurement of walls’ transmittance and air infiltrations, together with thermography analysis, enabled evaluating the conservation state of the buildings’ envelope. Upon analyzing all this data, it is evident that there is potential to enhance the design of future modules, improving the thermal comfort while significantly reducing the energy consumption. This will contribute to decrease the logistics and environmental impacts of these research stations, crucial considerations in human activity on the Antarctic continent.

Intra and interspecific differences in desiccation tolerance in native and alien Antarctic springtails in geothermal grounds.

The extreme low humidity and temperatures in Antarctica make it one of the harsher areas for life on our planet. In a global change context, environmental barriers that prevented the arrival of alien species in Antarctica are weakening. Deception Island, one of the four active volcanoes of Antarctica, is especially vulnerable to the impacts of alien species. Geothermal areas (GA) in this Island offer unique microclimatic conditions that could differentially affect native and alien soil arthropods. Here we explore the desiccation tolerance of a native (Cryptopygus antarcticus) and an alien (Proisotoma minuta) springtail (Collembola) species to these extreme environmental conditions. GA and non-geothermal areas (NGA) were selected to evaluate intra- and interspecific variation in desiccation tolerance. Populations of P. minuta from GA had greater desiccation tolerance than populations from NGA. However, desiccation tolerance of C. antarcticus did not differ between GA and NGA. This native species had greater desiccation tolerance than the alien P. minuta, but also greater body size. Our findings show that the alien P. minuta responds differently to environmental conditions than the native C. antarcticus. Furthermore, body size may influence desiccation tolerance in these two springtail species.

Evaluation and Modelling of the Coastal Geomorphological Changes of Deception Island since the 1970 Eruption and Its Involvement in Research Activity

Deception Island is an active volcano with a submerged caldera open to the sea called Port Foster. Several post-caldera-collapsed volcanic events, as well as hydrodynamics, have changed its inner coastline, shaping new volcanic deposits. A hydrodynamic model is presented to predict accretion and erosion trends in this bay, which could have an impact on the mobility of researchers and tourists. New historical orthophotos and spatio-temporal differences between digital elevation and bathymetric models were used for validation purposes. The model reveals that the south-facing coast is more susceptible to erosion, while the east- or west-facing coast experiences sedimentation. A visual study for the periods 1970–2003 and 2003–2020 in Port Foster obtained similar annual erosion/accretion lineal rates (0.3–2 m/year) in the areas not affected by the last eruptive period, as well as increases of 0.023 km2/year and 0.028 km2/year of the inner bay and coastal sedimentation rates of 0.007 km2/year and 0.002 km2/year, respectively. Only part of the significant total volume loss is received within the bay, including its own erosion, and accumulates on the bay bottom. This is largely because the volume input is composed of snow, and it is also due to the transfer of material outside to balance the figures.

Skeletal Mg content in common echinoderm species from Deception and Livingston Islands (South Shetland Islands, Antarctica) in the context of global change

Echinoderms with high levels of magnesium (Mg) in their skeletons may be especially sensitive to ocean acidification, as the solubility of calcite increases with its Mg content. However, other structural characteristics and environmental/biological factors may affect skeletal solubility. To better understand which factors can influence skeletal mineralogy, we analyzed the Mg content of Antarctic echinoderms from Deception Island, an active volcano with reduced pH and relatively warm water temperatures, and Livingston Island. We found significant interclass and inter- and intraspecific differences in the Mg content, with asteroids exhibiting the highest levels, followed by ophiuroids and echinoids. Specimens exposed to hydrothermal fluids showed lower Mg levels, which may indicate local environmental effects. These patterns suggest that environmental factors such as seawater Mg2+/Ca2+ ratio and temperature may influence the Mg content of some echinoderms and affect their susceptibility to future environmental changes.