Blood Falls is a unique feature that appears at the snout of the Taylor Glacier in the upper Taylor Valley, East Antarctica. It is an iron-rich brine that occasionally gets expulsed from a subglacial source due to the weight and movement of the overlying glacier. The brine that emanates stains the glacier as it oxidizes at the surface and flows towards the West Lobe of Lake Bonney (WLB). Recent work (Spigel et al. 2018, Lawrence et al. 2020) has shown that, besides the Blood Falls contribution, the brine enters the WLB all along the front of Taylor Glacier, creating cold water anomalies at the depth where this subglacial brine’s density is matched by the surrounding lake water. Mikucki et al. (2015) detected substantial brine at the base of Taylor Glacier using an airborne transient electromagnetic sensor. Badgeley et al. (2017) used radio echo sounding to delineate the brine further and to show that there are subglacial flow pathways that direct the brine to the centre and south side of Taylor Glacier’s snout, in addition to what flows from Blood Falls.

Reproductive synchrony is common in populations that inhabit seasonal environments where reproductive timing is important to offspring survival. Weddell seals (Leptonychotes weddellii) reproduce in strongly seasonal Antarctic environments and are known to exhibit reproductive synchrony that varies by latitude, whereby more southerly populations give birth later. The Erebus Bay population of Weddell seals is the southernmost mammal population in the world, and birth-date synchrony has been demonstrated in this population. Various life history correlates including sex, maternal age and reproductive status have been identified as predictors of birth timing, but all prior work has been done on pups born to locally born mothers. Immigrant females originating from unknown sites in more northerly locations also produce pups in Erebus Bay and may have different birth timing due to the earlier average birth dates in their natal colonies. Using 22 years of capture-mark-recapture data for Weddell seals in Erebus Bay, we aimed to assess whether the timing of birth dates for pups born to immigrant mothers differs from that of pups born to locally born mothers. To our knowledge, this is the first time that such a comparison has been studied in a wild population. Birth dates were examined using Bayesian linear regression. We analysed birth dates from 7539 pups (4932 from locally born mothers, 2607 from immigrant mothers) born to 2210 mothers (1254 locally born, 956 immigrant) and found that there were no biologically impactful differences in the birth dates of pups born to locally born or immigrant mothers. Additionally, birth-date patterns for immigrant mothers were similar to those for locally born mothers with respect to various traits. Our results demonstrate that immigrant Weddell seal mothers can synchronize birth timing with locally born mothers. More research is required to understand the underlying mechanisms that allow for immigrant seals to achieve birth-date synchrony.

Antarctic ice-free coastal environments, like the Vestfold Hills (East Antarctica), are shaped by a complex interplay of physical processes. This study synthesizes new data and existing research from the Vestfold Hills across marine, terrestrial and cryosphere science, meteorology, geomorphology, coastal oceanography and hydrology to explore interconnected processes ranging from icescape morphology and sediment transport to ocean-floor scouring and ocean-atmosphere interactions. Coastal landforms and habitats result from the interaction of marine dynamics with the aeolian and fluvial transport of glacially derived sediments and geomorphic features. Rocky shorelines dominate the region, and extensive fjords are prominent coastal features, whereas intertidal sediments and beaches are scarce. The marine environment is characterized by slow currents, low-energy waves, annually variable land-fast ice, irregular sedimentation rates and a geomorphologically complex shoreline. Aeolian and fluvial sediment deposition into coastal waters and onto sea ice can significantly impact local ecological and physical processes. Human activity further modifies these dynamics. Ice-free coastal areas such as the Vestfold Hills are predicted to experience substantial environmental shifts due to climate change. Wind speeds, temperature and precipitation are increasing in the Vestfold Hills. Retreating grounded ice sheets are likely to expand this coastal area and increase meltwater and sediment inputs into nearshore marine systems. Concurrently, changes in sea-ice extent, thickness and/or duration may profoundly alter the structure and function of this coastal environment.

Here we describe a new springtail species found on Byers Peninsula, Livingston Island. The new species, Folsomotoma punctata, is known from sub-Antarctic South Georgia, but this is a first occurrence of this species for the South Shetland Islands and the Maritime Antarctic, increasing the total species number to 15. Considering the widespread distribution of F. punctata across Byers Peninsula, it seems most likely that this species has been present for a long time. That it was only now reported reflects the limited arthropod surveys conducted in this region of the South Shetland Islands, and highlights the need for more thorough and high spatial resolution systematic surveys across different vegetation and habitats to better understand the terrestrial biodiversity patterns in Antarctica.

The finding of an incorrect non-Antarctic locality assigned to a specimen of Trematomus loennbergii at the Natural History Museum, London, led to the discovery of two (of three) syntype specimens, previously considered missing, of this species. The third syntype, a larger specimen in better condition, is designated as the lectotype of T. loennbergii; the two newly discovered specimens, re-identified as Trematomus pennellii, become paralectotypes.

Emperor penguins are highly reliant on stable fast ice for successful breeding, and some studies project possible quasi-extinction for most colonies by 2100 due to future sea-ice loss. To better understand the future response of emperor penguins to ocean-climate warming and the possibility of major changes to their habitat, it is essential to better understand how colonies have responded to past changes in ice conditions. In this study, we identify the historical locations of the SANAE, Astrid and Mertz colonies in all available Landsat 4–9, Advanced Spaceborne Thermal Emission and Reflections satellite (ASTER) and Sentinel-2 imagery for the period 1984–2024. We record the location and surface type of the colonies’ breeding locations each year while also recording major calving events, early fast-ice breakouts, distance to the fast-ice edge, and colony location span within a season. The results show that colonies usually return to approximately the same sites annually, but we observe variations due to major calving events. Following such events at Mertz (2010) and SANAE (2011), colonies relocate to different sites, where they may be more vulnerable to early fast-ice breakout or must travel longer distances to the fast-ice edge. In subsequent years, the colonies eventually return to sites close to their original location. Additionally, we observe early fast-ice breakouts that may impact breeding success at Mertz and SANAE colonies, including as early as September at Mertz (2016). Such breakouts coincide with both broader sea-ice lows and variations in colony location. Furthermore, all three colonies move onto the adjacent ice shelf in some years (and at Astrid and Mertz, also icebergs), including when stable fast ice is available, suggesting that this behaviour may be more common than previously thought. Observation of these behaviours contributes to broader understanding of emperor penguins’ adaptability and will aid future efforts to model the response of the species to ice loss.

Poikilothermic and short-lived drifter species such as zooplankton are highly responsive to climate-driven changes and frontal systems in the Southern Ocean. To understand these changes, ongoing assessment of zooplankton is essential. Changes in abundance, biomass and species composition of zooplankton in the Indian sector of the Southern Ocean were assessed during the austral summer of 2022/2023 using a ring net that was towed obliquely from an average depth of 200 m to the surface. Thirty-six zooplankton taxa were identified at seven stations, with copepods constituting 64% of the population across 23 species. Zooplankton abundance and biomass were higher in Transect 2 (60–64°S) compared to Transect 1 (50–54°S). A cluster analysis revealed four zooplankton community groups. Notably, the distribution patterns of non-copepod taxa appeared to be influenced by diel vertical migration behaviour, which was closely tied to seasonal dynamics and the timing of sampling. This study improves our understanding of how different oceanographical fronts and behavioural patterns shape zooplankton communities in the Southern Ocean, emphasizing the need for improved sampling to include smaller zooplankton species and to better resolve temporal dynamics.

The diverse cutthroat eel family Synaphobranchidae comprises 13 genera and 57 species of mostly deep-sea fishes documented from all oceans. Here, we report on the catch of a single synaphobranchid specimen in the Kong Haakon VII Sea off Dronning Maud Land, representing the first record of the genus Ilyophis in the Southern Ocean. The specimen was trawled at a depth of 1500 m during the 2019 joint expedition of the Norwegian Polar Institute, Institute of Marine Research (Norway), the University of Bergen (Norway), the Arctic University of Norway, the University of Science and Technology (Norway) and the Stellenbosch University (South Africa) onboard the Norwegian research vessel Kronprins Haakon. The specimen is deposited in the ichthyological collection of the University Museum Bergen. In this study, we tentatively identify the specimen as Ilyophis cf. maclainei based on an integrative taxonomic approach. Phylogenetic analysis of mitochondrial partial cytochrome oxidase I places the Antarctic specimen in a clade of sequences deposited in Barcode of Life Data System (BOLD) as Ilyophis sp., Ilyophis cf. brunneus and Ilyophis brunneus. Morphological data show overlaps in some morphometric and meristic characters with I. brunneus and the recently described I. maclainei - with no genetic samples currently being available for the latter. Our analysis reveals taxonomic issues within I. brunneus and the need for increased sampling and a worldwide taxonomic revision of I. brunneus. The full mitochondrial DNA of the Antarctic specimen is reconstructed as a resource for future research.

Dry permafrost underlain by ice-cemented permafrost has been reported in several locations in Antarctica. Initially thought to be relic ice, it is now understood that this subsurface ice is in equilibrium with the surface conditions, although it is not in equilibrium with the atmosphere. We use year-round data from University Valley in the Dry Valleys and Elephant Head in the Ellsworth Mountains to investigate the seasonal variations in water vapour flux that control the depth to the ice table under dry permafrost. Our analysis shows that the mean annual water vapour density of the soil surface exceeds the atmospheric value by a factor of up to ~2 due to summer snow. The attenuation and phase shift of the annual temperature cycle with depth result in colder temperatures at the ice table than at the surface of the soil in summer. We conclude that this temperature gradient, combined with the summer snow, provides the flux of water to the ice table necessary to maintain the ice. In University Valley, reducing the snow days by 40% moves the stability depth of the ice table from 42 to 66 cm. Increasing the snow days by 60% shifts the ice table to 17 cm. These variations can explain the observed gradient in the depth to the ice table in University Valley.

Located in the central part of the Western Antarctic Peninsula, the Argentine Islands-Kyiv Peninsula region is a hotspot of moss diversity, with 51 species and one variety currently known. However, no studies have specifically addressed the distribution of rare mosses in this region. Applying the only definition of moss rarity currently available for Antarctica, we identify very rare (one to two unique occurrences) and rare (three to five unique occurrences) moss species in the region and present a biogeographical analysis of their spatial distribution with corresponding maps, based on a comprehensive synthesis of archival published occurrence data. Of the 51 recorded species, 23 were classified as locally very rare or rare. Cape Tuxen, Galindez Island, Darboux Island and Cape Pérez hosted the highest concentrations of rare moss diversity, with eight, seven, seven and six species, respectively. Five rare species were recorded at Petermann Island, four at Booth and Lahille islands and three each at Diorite, ‘Eight’ and Uruguay islands. Additionally, several locations hosted species with unique characteristics, including their only known occurrence in the Antarctic Peninsula or at their known range edge. Very rare and rare species assemblages showed only partial overlap among sites: the four most species-rich sites shared several taxa, but no species occurred at all sites. Uruguay, Diorite and ‘Eight’ islands together represented a full moss species pool of the four most species-rich sites. In addition, some sites supported distinct species not recorded elsewhere in the region. Notwithstanding the limitations of the available survey data, these findings highlight the regional significance of the Argentine Islands-Kyiv Peninsula region within the Western Antarctic Peninsula for moss diversity in terms of the recognized criteria required for developing proposals for formal protection under the Antarctic Treaty.

Maritime Antarctica experiences less extreme environmental conditions than much of the Antarctic continent and has further been impacted by considerable warming in recent decades. While inventories exist of macroscopic Antarctic biodiversity, and there is some information available on culturable microorganisms, much less is known about the presence of other cryptic eukaryotic organisms. DNA metabarcoding provides a method for assigning the DNA of multiple different organisms simultaneously from environmental samples. In this study, we used DNA metabarcoding to investigate the environmental DNA (eDNA) diversity of non-fungal eukaryotic organisms associated with rocks in the South Shetland Islands. Five sampling points were selected from a stratigraphic profile at Mazurek Point, King George Island. Collected rock samples were pulverized, total DNA was extracted and amplicons were generated using ITS2 primers, then these were sequenced using an Illumina MiSeq system. Sequences representing five kingdoms and nine phyla were retrieved. Viridiplantae was the most diverse and abundant group, with 42 assigned taxa, followed by Chromista, with 22 assigned taxa. The precise lithology did not influence the assigned diversity. The majority of assigned taxa are widespread and plausibly present in the area, but some are not known from Antarctica, including some from tropical regions. The latter assignments probably result from the limitations of the databases used, although in some cases they may indicate evidence of anthropogenically associated or naturally dispersed DNA-containing material.

The highest-elevation and a far southern pond in the Transantarctic Mountains is briefly documented. The small pond, at an elevation of ~2350 m, was frozen when it was visited in the 1963–1964 field season, and satellite imagery suggests it has remained frozen since 2010. A second frozen pond is noted, but its precise location is uncertain.

Many authors have studied the biogeography of the Southern Ocean (SO), defined its limits and proposed their division into biogeographical zones and provinces. In this work we analyse the biogeography of sea slugs in a broad sense (Mollusca, Gastropoda, Heterobranchia) in the different areas and zones of the SO below 41°S. Most of the published scientific publications, databases and technical reports where records of benthic sea slugs appear in the SO have been analysed in addition to our own records, cataloguing a total of 355 different benthic species. The following areas and zones of the SO have been considered: Antarctica (Weddell Sea, West Antarctica, Ross Sea, East Antarctica), the sub-Antarctic zone (Falkland Islands, South Georgia Island, South Orkney Islands, South Sandwich Islands, Bouvet Island, Crozet and Prince Edward islands, Kerguelen Islands, Macquarie Island), southern South America (Patagonia/Magellan), Tasmania and New Zealand (South Island). A presence/absence table for all recorded species in the different zones has been compiled, and the differences and similarities between them have been calculated using the Sorensen index. The best representation has been obtained by classifying the zones into five groups: G1 (the four Antarctic zones, South Georgia Island, South Sandwich Islands, South Orkney Islands), G2 (Kerguelen Islands, Crozet and Prince Edward islands and Macquarie Island), G3 (Falkland Islands and Patagonia/Magellan), G4 (Tasmania and New Zealand’s South Island) and G5 (Bouvet Island). In addition, the concordance between the non-hierarchical classification (K-mean) and the hierarchical classification obtained using the WARD and UPGMA cluster analysis methods has been verified. The representative and distinctive species of each of these groups are indicated. In this work, as regards benthic sea slugs, the biogeographical affinities between the Antarctic zones and some of the sub-Antarctic zones are confirmed, as well as between the fauna of these molluscs in the Patagonian/Magallan zone and the Falkland Islands, while the affinities between the other zones need further confirmation when more species records become available.

There is clear evidence that rapid warming has been fuelling significant changes in the ocean and cryosphere in the Antarctic Peninsula region. Less is known about how terrestrial biological ecosystems, particularly plants, are responding to warming and hydroclimatic change. We show that high evaporative environmental conditions and microclimate associated with topography lead to humidity-dependent evaporative effects on the oxygen isotope ratios (δ18O) of moss waters and α-cellulose in the northern Antarctic Peninsula, based on a spatial (> 400 km) isotopic survey at 14 sites over 24 days during summer 2020. The δ18O of moss waters define a water line of δ2H = 4 × δ18O + 37 for Polytrichum strictum and δ2H = 3.8 × δ18O + 38.9 for Chorisodontium aciphyllum, indicating enrichment compared to line slopes ranging from 6.7 to 8.5 for snow, standing water, previous published snapshots of moss waters and the long-term local meteoric water lines along the Antarctic Peninsula. The δ18O of moss waters negatively correlated with relative humidity (which ranged from ~50% to 100%) and not with temperature or latitude, where a higher δ18O indicates increased evaporative enrichment or dry conditions. A positive correlation between the δ18O of moss waters and α-cellulose (ρ = 0.397, P = 0.011) for P. strictum (ρ = 0.533, P = 0.007) but not C. aciphyllum suggests that the high evaporative conditions from the season imprinted on the cellulose. Lastly, we found significant positive correlations between topographic aspect (north-exposedness) and the δ18O of moss waters (ρ = 0.569, P < 0.001) and α-cellulose (ρ = 0.579, P < 0.001), indicating that irradiance on north-facing slopes promotes drier conditions and evaporative enrichment. Topographic aspect (and resulting microclimate) is an important and predictable determinant of the δ18O of moss waters and α-cellulose. This study highlights that mosses are sensitive recorders of climatic and non-climatic conditions in polar terrestrial ecosystems.

The McMurdo Dry Valleys in the Ross Sea Region of Antarctica represent a globally unique desert ecosystem where water availability is likely to change under global warming scenarios, thus influencing the distribution and abundance of biota. Using the Random Forest machine learning model, we focused on the spatial distribution of macroscopic terrestrial biota (moss, cyanobacteria, lichen, springtails and mites) in the Dry Valleys. A wetness index, explicitly driven by satellite-derived glacier surface temperatures and meltwater routing, was used along with biological survey data collected over six field seasons (2009–2014) as part of the New Zealand Terrestrial Biocomplexity Survey (n = 886 sites). Our analyses use the full extent of survey data available and include the larger Taylor, Wright and Victoria valleys, as well as data from the previously studied Miers, Marshall and Garwood valleys. The overall model accuracies were mixed (kappa statistic: 0.34% and 17.3% variance explained). However, the resulting predictive maps derived from the model and the influence of the different explanatory variables align with field observations and theoretical expectations. The models show that distance from coast was an important driver for the biota, as well as elevation and temperature. The predictive maps provide an initial model of the distribution of biota in the Dry Valleys and can guide future sampling as well as inform conservation and management strategies. Our research highlights the importance of biological survey data for use in spatial predictive modelling as well as the need to obtain representative samples from a wide range of different habitats (e.g. wet vs dry).

In 1988, meteorological measurements started at the Spanish research station Juan Carlos I (JCI) on Livingston Island. A second station - Gabriel de Castilla (GdC) - was installed in 2005 on Deception Island. These long-term measurements improved our climatological understanding of the western region of the South Shetland Islands (SSI), a region that has received less attention than the more station-populated King George Island in the central SSI. Here, we present a complete climatological analysis of these stations after undertaking a full quality control process of the data. This analysis covers temperature, wind, precipitation, radiation, relative humidity and pressure, as well as trends and variability. The results show: 1) the stations along the western SSI coastline, particularly JCI, are warmer than those on the central SSI, especially in summer, 2) at GdC, winters are colder due to stagnant cold air pooling within the Deception Island caldera, 3) the importance of island orography in shaping local climatology, especially regarding wind patterns, and 4) the critical need to correct precipitation measurements for undercatchment of solid precipitation by common pluviometers. This study provides a climatological framework to support further research conducted in the region.

Deception Island is an active, caldera-forming volcano whose surveillance is critically constrained by its extreme Antarctic isolation, scarce resources and limited seasonal human access. This study addresses these challenges by presenting an innovative Global Navigation Satellite Systems (GNSS) geodetic surveillance framework specifically adapted for such a remote environment. Our approach establishes a key operational distinction between non-real-time monitoring and near-real-time surveillance via a semi-continuous wireless network. We effectively resolve the inherent trade-off between promptness and precision by applying signal enhancement methods (e.g. Kalman filtering) to maintain millimetric accuracy in deformation detection, even when utilizing the high sampling rates (1 Hz) essential for rapid assessment. The resulting model allows for the rigorous isolation of the local volcanic signal from the complex regional tectonic kinematics. Crucially, data analysis reveals recurrent 3 year cycles of inflation and deflation in the magmatic system, strongly correlated with seismicity, which validates ground deformation as a reliable volcanic precursor. The primary practical advance is the validation of a dual-term hazard forecasting system: 1) mid-term (months) forecasts based on long-term time-series analysis to facilitate safe inter-campaign operations and 2) short-term (days) forecasting during periods of unrest using ground displacement acceleration, complemented by a magma injection model to predict the spatial location of potential vent openings. This validated and technologically adjusted framework provides an optimized and transferable template for continuous geodetic surveillance in other isolated, active polar volcanoes.