The numerous ephemeral glacial meltwater streams that flow during the summer in the McMurdo Dry Valleys of South Victoria Land, Antarctica, provide habitats for microbial mats. One of the common mat types is composed of Chlorophyta (colloquially known as a ‘green mat’ due to its colour). While the presence of these mats is regularly monitored, their taxonomic makeup is still under investigation. Using 18S rRNA gene sequencing, the composition of the chlorophyte-dense mats from between rocks and in the main channel from several streams across two valleys was examined. Samples were maintained in native stream water, and select samples from representative locations were transferred to Bristol Medium. The appearance of other eukaryotic species - diatoms and tardigrades - in these green mats completed this integrated study. The results show that the relative abundance of Chlorophyta was significantly increased with the introduction of inorganic nitrogen from Bristol Medium. Chlorophyte taxa in the Hazenia and Pleurastrum genera dominated the samples across both sample types (rock or exposed) and treatments (Antarctic water or Bristol Medium). Furthermore, a reduction in overall sample diversity was observed in samples in Bristol Medium, suggesting preferential nitrogen utilization by these chlorophytes.

Leopard seals (Hydrurga leptonyx) lead solitary lives, mainly associated with sea ice, and they are parasitized by the sucking louse Antarctophthirus ogmorhini, one of the few known marine insects and probably the only group adapted to survive in deep-ocean environments. A challenge for seal lice is that their eggs do not survive underwater, requiring them to complete their life cycle during the host’s reproductive or moulting season. We investigated the infestation parameters of A. ogmorhini in leopard seals on the Danco Coast, Antarctic Peninsula, estimating prevalence and mean abundance, comparing by sex, age class and interannual variability and determining the relationship between these parameters and the body condition of the seals. Over four field seasons (2014, 2015, 2019 and 2020), we collected data from 50 seals: 12 females and 38 males, including 47 adults and 3 juveniles. The overall prevalence (14%) was the lowest recorded for an Antarctic seal, with higher rates in juveniles (33.3%) than adults (12.8%) and in males (15.8%) compared with females (8.3%). Generalized linear models analysis, considering body condition and interannual variability, did not reveal a strong correlation between body condition and lice infestation. Although no strong correlation was found, there is some indication that seals in poorer condition may be more heavily infested.

We evaluated the physiological condition of the Pygoscelis penguins at Isla 25 de Mayo/King George Island (Antarctica Peninsula). Samples were collected from adults and chicks of Adélie (Pygoscelis adeliae, n = 20 each), gentoo (Pygoscelis papua, n = 20 chicks and n = 24 adults) and chinstrap penguins (Pygoscelis antarcticus, n = 18 each). We analysed haematological and biochemical parameters as indicators of health, immune response and nutrition. Gentoo penguin chicks exhibited higher haematocrits, indicating development linked to erythropoiesis and reticulocyte release from bone marrow or signalling dehydration related to fasting periods in chicks. Adélie penguins had increased total leukocyte counts, basophils and eosinophils, whereas gentoo penguins showed elevated heterophils and decreased lymphocytes, resulting in a higher heterophil/lymphocyte ratio stress index, possibly due to the impact of human activities. Chinstrap penguins from a remote area exhibited the lowest heterophil/lymphocyte ratio values. Adélie penguins showed more erythrocytic nuclear abnormalities, indicating sensitivity to environmental deterioration due to human impacts. The biochemical results were less consistent; Adélie penguins had higher cholesterol, whereas gentoo penguins had elevated triglycerides. Gentoo penguins showed dietary adaptability based on prey availability in this area. Our findings highlight the vulnerability of Adélie penguins and contribute to a 20 year physiological monitoring dataset for Antarctic penguins, which will aid future comparative studies.

Antarctic glaciers have been considered classically uninhabited. However, they constitute an authentic biome and are populated by microorganisms that not only survive in them but also maintain an active metabolism. The South Shetland archipelago is a good study model to observe the diversity and evolution of the microbial populations that inhabit its glaciers. From a geological point of view, this archipelago is of considerable interest due to the intense and relatively recent volcanic eruptions on Deception Island. Additionally, it has been a place of transit for human and animal populations over time. All of these factors have influenced the composition and diversity of the microbial communities inhabiting the glacial ice. Among these microorganisms, a great diversity of bacteria, archaea, viruses and microeukaryotes such as algae and unicellular fungi have been identified thanks to high-throughput technologies. These cold-adapted microorganisms develop molecular mechanisms of adaptation to the extreme environment they inhabit and contribute to global energy cycles through the processing of organic and inorganic compounds. This review summarizes current knowledge on the biodiversity, ecology and molecular mechanisms of adaptation of cold-adapted microorganisms, and it details the specific characteristics of the microbial populations housed in the Antarctic glaciers in the South Shetland archipelago.

Submarine landforms in polar fjords provide essential insights into glacier responses to climate change in the Maritime Antarctic. This work aims to reconstruct the groundline of a palaeo-ice stream throughout the Holocene in Admiralty Bay, King George Island. The landforms were investigated using multi-resolution topobathymetric data based on seismic and multibeam surveys. The inner sector features shallow moraine banks and elongated glacial lineations, in contrast to the deeper moraine banks observed in the middle and outer regions of the fjord. Elongated glacial lineations indicate a north-east to south-west ice flow and a wet-based thermal regime. At ~9000 years bp, the grounding line was at the Admiralty Bay fjord’s mouth. In the middle of the fjord, a prominent morainal bank reveals the palaeoglacier’s grounding line. The grounding line significantly changed position after this stillstand in response to climatic variability (Mid-Holocene, at 4500–2800 years bp) and was conditioned by the deep bathymetry. The continued retreat of the ice in the Holocene possibly led to a division of the palaeo-ice stream into outlets or tidewater glaciers. MB7 and MB9 indicate the position of the grounding line during a major stillstand at the end of the inlets. The bedrock topography and fjord geometry influenced the deglaciation pattern of Dobrowolski Glacier in Martel Inlet, and the moraine banks recorded two final major stillstands. The retreat rates in Martel Inlet have increased due to the loss of anchoring points and rising temperatures after the Neoglacial period. The morainal banks present in the proximal environments at Martel Inlet are smaller, discontinuous and spaced, indicating the retreat behaviour in the last 7 decades.

Population monitoring provides information on species conservation status. We reassess the status of the southern elephant seal population at Macquarie Island. The number of cows on the isthmus, ~20% of the total population, correlated with counts for the whole island (i.e. they reliably indicate island-wide trends). Cow numbers within the isthmus decreased from ~9400 in 1949 to ~2550 in 2023 at −1.1% year−1, similar to the −0.8% year−1 from 1984 to 2023 when counts were made annually (before 1984, counts were less systematic). This contrasts with all other southern elephant seal populations, which are either stable or increasing. There was also considerable year to year variability (± 350 cows year−1) in the numbers of cows ashore, indicating individuals skipping breeding. Counting errors may contribute to this variability but are unlikely given that the isthmus study area harems are small, typically < 200 cows. We found no link between cow numbers and summer ocean conditions using the Southern Annular Mode as a proxy (i.e. prior to blastocyst implantation), and it remains unclear what is causing this variation. Nonetheless, several other studies have suggested changing prey conditions during the winter are the most likely cause of this overall and ongoing decrease.

Soft-bottom areas are among the least explored ecosystems in Antarctica. To improve our understanding of these environments, we performed a preliminary assessment of the marine macrobenthic fauna in False Bay, Livingston Island, near Huntress Glacier (South Shetland Islands, Antarctica). Fourteen Van Veen grabs (0.018 m2 area) were deployed at two stations within the bay at depths of 174–210 m. The samples provided values up to 159 556 individuals m-2 within 15 major taxonomic groups. Annelida Polychaeta was predominant (~93%), followed by Ophiuroidea and Bivalvia at the external station and Bivalvia and Amphipoda at the internal site. Maldanid polychaetes, particularly Maldane sarsi antarctica, constituted 84.62–90.74% of the samples. Total biomass was 6673.25 grams of wet weight per square metre, mainly from Ascidiacea, Polychaeta, Holothuroidea and Ophiuroidea. Approximately 12% of the macrofauna inhabited the sediment (epifauna), while 88% lived into the sediments (infauna). Regarding feeding modes, specimens were detritivores (77.91–82.71%), suspension-feeders (7.59–13.37%) and, infrequently, predators (4.07–5.07%) and grazers (4.63–4.65%). According to the compilation of occurrence records in the Southern Ocean, M. sarsi antarctica has a circum-Antarctic distribution. Furthermore, the population of this species in False Bay appears to be stable and undisturbed with a normal distribution in size structure, with a higher proportion of individuals at intermediate sizes (2.85–4.26 cm). This study provides for the first time detailed descriptions of the macrofauna from the soft bottoms of False Bay, representing a preliminary effort to monitor ecological shifts in this critically important and understudied region, which is experiencing rapid environmental changes within Antarctic marine ecosystems.

Airborne investigations are a keystone for understanding the Antarctic environment across many scientific disciplines. Over the past decade and more, the use of drones has been proposed as a means to enhance this airborne capability. Small quadcopter/multi-rotor drones, typically flown within visual line of sight, have become a well-established and routinely deployed technology. However, larger fixed-wing uncrewed aerial vehicles (UAVs) capable of beyond-visual-line-of-sight missions similar to traditional crewed aircraft have not been routinely deployed. Here, we report on the first deployment of a large (10 m wingspan) UAV for scientific data collection from Rothera Research Station, Antarctica. The platform, a Windracers Ultra, flew 2978 km over 25 missions, collecting a range of scientific observations including visual and hyperspectral imagery, atmospheric turbulence data and gravity and magnetic data. All science missions were carried out beyond visual line of sight and were up to 2.25 h/260 km long. Missions included coordination with and operation alongside crewed aircraft. Our field season has successfully demonstrated that large UAVs can play a significant role in Antarctic data collection, working alongside crewed aviation to improve our understanding of Antarctica.

This study investigated the temporal and spatial variability of temperature, salinity, pH and suspended particulate matter (SPM) in surface water from Admiralty Bay, Antarctic Peninsula. The study aimed to understand how water parameters were affected during high meltwater runoff in the summer of 2019/2020, to verify the influence of rapid temperature changes from the spring and summer of 2022/2023 and to identify the sources of SPM. In January 2020, the water temperature and salinity in the region were influenced by rapid shifts in environmental conditions, while pH and SPM remained similar to previous years. The same pattern was observed in the summer of 2022/2023, with only water temperature and salinity varying towards the end of the summer. The SPM concentrations were mainly influenced by wind speed. Spatially, there was no sectorization between different inlets, with specific sites influenced by meltwater and higher SPM values. The study suggests that strong winds are the primary factor influencing SPM resuspension in Admiralty Bay, with atmospheric deposition and meltwater also contributing. This dynamic variability in the water column highlights the need to closely monitor the water’s physicochemical parameters and the influence of atmospheric conditions. This study contributes to our understanding of the SPM sources on the Antarctic coast.

In the coming decades, Antarctica will face a range of challenges linked to transnational issues such as climate change, plastics pollution and geopolitical tension. Such challenges make it increasingly important for the Antarctic sector to ensure that there is broad public support for the ongoing political and environmental stewardship of the southern polar region. Initiatives such as the 2032–2033 International Polar Year offer a unique opportunity to enhance public knowledge of and investment in Antarctic research, but little is currently known about how well-suited the Antarctic sector is to the work of public engagement. In this paper, we present the results of an exploratory survey (n = 76) conducted in 2022–2023 to examine the Antarctic sector’s capacity to engage with the public. We find that, while public engagement work is certainly happening in the Antarctic sector, it is often ad hoc and under-resourced, and the skillset associated with engagement work is commonly undervalued. In order to capitalize on the opportunities presented by the next International Polar Year, we recommend that the organizations within the Antarctic sector collaborate on a joint public engagement strategy.

Reducing plastic pollution of the Antarctic environment is a priority for the Antarctic Treaty Consultative Meeting (ATCM) and Council of Managers of National Antarctic Programs (COMNAP). Polyester flags mounted on bamboo poles are commonly used by governmental and tourism operators as markers of safe travel routes, scientific equipment and depots in snow-covered areas. Polar environmental conditions can rapidly degrade polyester flags, resulting in plastic release into the environment. This study aimed to quantify the degree of polyester flag degradation and investigate alternative, less polluting flag types. Pre-weighed flags of four types - standard polyester, hemmed polyester, organic cotton canvas and Ventile${}^\circledR $ (a tight-weave cotton fabric) - were deployed close to Rothera Research Station, Antarctic Peninsula, from February 2023 to January 2024, after which any changes in weight were recorded. On average, each standard polyester flag lost 25.5% (± standard error (SE) 0.8) of its weight, equating to the release of 8.3 g of plastic into the environment; however, hemming the flag reduced this loss to 13.3% (± SE 3.7). Ventile${}^\circledR $ was almost as durable as unhemmed polyester (loss of 26.9% (± SE 3.8)), whereas cotton canvas was the least durable (loss of 44.1% (± SE 4.3)). Switching from standard polyester to Ventile${}^\circledR $ flags would prevent the annual release of > 8.3 kg of plastic into the environment around Rothera Research Station, and potentially ~300 kg across all Antarctic operator activities. This is a conservative estimate compared to a potential additional 800 kg of plastic that could be lost to the environment due a high proportion of deployed flags not being recovered. Further investigations to identify cost-effective sustainable flag materials are recommended to comply with ATCM and COMNAP recommendations concerning plastic management in Antarctica.

Primary production is fundamental to ecosystems, and in many extreme environments production is facilitated by microbial mats. Microbial mats are complex assemblages of photo- and heterotrophic microorganisms colonizing sediment and soil surfaces. These communities are the dominant producers of the McMurdo Dry Valleys, Antarctica, where they occupy lentic and lotic environments as well as intermittently wet soils. While the influence of microbial mats on stream nutrient dynamics and lake organic matter cycling is well documented, the influence of microbial mats on underlying soil is less well understood, particularly the effects of microbial mat nitrogen and carbon fixation. Taylor Valley soils occur across variable levels of inorganic phosphorus availability, with the Ross Sea drift containing four times that of the Taylor drifts, providing opportunities to examine how soil geochemistry influences microbial mats and the ecological functions they regulate. We found that inorganic phosphorus availability is positively correlated with microbial mat biomass, pigment concentration and nitrogen fixation potential. Additionally, our results demonstrate that dense microbial mats influence the ecological functioning of underlying soils by enriching organic carbon and total nitrogen stocks (two times higher). This work contributes to ongoing questions regarding the sources of energy fuelling soil food webs and the regional carbon balance in the McMurdo Dry Valleys.

Antarctic terrestrial ecosystems, covering less than 1% of the continent, are under increasing anthropogenic threats, particularly from climate change and tourism. This study focuses on the impact of human trampling on soil microbial communities in Barrientos Island (South Shetlands archipelago), a frequently visited location. Soil samples were collected within and at the edge of two established paths representing varying levels of human disturbance. Physical and chemical analyses revealed significant differences between the paths, potentially creating anaerobic conditions favorable for specific microbial taxa. Thus, microbial communities also differed between the paths. Aerobic heterotrophic taxa were dominant in the less disturbed path, while anaerobic taxa such as Bacteroidetes vadinHA17 thrived in the more compacted path. Although alpha diversity indices did not differ, beta diversity analyses showed notable distinctions, particularly between the paths rather than trampled and untrampled areas. These findings suggest that microbial communities may recover following the stop of human activity, but also that indigenous microbial communities or other overlooked factors may be influencing the recovery potential. This study thus offers a starting point for similar research, as it highlights the need for further investigation to determine whether human trampling or other environmental factors are primarily responsible for these differences.