Although there is increasing evidence that birds have individual chemical profiles that can be used in different social contexts, partner scent recognition has only been explored in procellariiform seabirds, a group of birds known for their highly developed olfactory system. However, olfaction is not restricted to Procellariiformes, and birds with smaller olfactory bulbs can also use chemical cues in different social contexts. More evidence from different bird groups is needed to disentangle whether olfaction plays a general role in partner recognition. We performed a choice experiment to examine whether chinstrap penguins Pygoscelis antarcticus can discriminate the scent of their partner from the scent of other conspecifics. Our results do not suggest a preference of penguins for the scent of their partners. Our results highlight the need to carry out additional studies to determine the mechanisms underlying partner recognition in penguins.

A rock cairn, with two matchbooks buried beneath, was found on the summit of the highest hill on Thomas Island, Bunger Hills, East Antarctica. The matchbooks are most likely from United States World War II-era ration packs, which were distributed to various military and civilian expeditions from the mid-1940s into the 1950s. Bunger Hills was first visited by United States Navy ‘Operation Highjump’ in February 1947, when a seaplane most likely landed on a marine inlet, rather than a lake as reported previously. Thomas Island was first visited by United States Navy ‘Operation Windmill’ in January 1948, when a survey point was established, and it is probably this location that is marked by the rock cairn. The matchbooks were replaced beneath the cairn and the rocks replaced. Just over 76 years had elapsed between burial of the matchbooks, construction of the cairn and their rediscovery.

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.

Increases in atmospheric CO2 have led to more CO2 entering the world’s oceans, decreasing the pH in a process called ’ocean acidification’. Low pH has been linked to impacts on macroalgal growth and stress, which can alter palatability to herbivores. Two common and ecologically important macroalgal species from the western Antarctic Peninsula, the unpalatable Desmarestia menziesii and the palatable Palmaria decipiens, were maintained under three pH treatments: ambient (pH 8.1), near future (7.7) and distant future (7.3) for 52 days and 18 days, respectively. Discs of P. decipiens or artificial foods containing extracts of D. menziesii from each treatment were presented to the amphipod Gondogeneia antarctica in feeding choice experiments. Additionally, G. antarctica exposed to the different treatments for 55 days were used in a feeding assay with untreated P. decipiens. For D. menziesii, extracts from the ambient treatment were eaten significantly more by weight than the other treatments. Similarly, P. decipiens discs from the ambient and pH 7.7 treatments were eaten more than those from the pH 7.3 treatment. There was no significant difference in the consumption by treated G. antarctica. These results suggest that ocean acidification may decrease the palatability of these macroalgae to consumers but not alter consumption by G. antarctica.

Penguins include 18 species of seabirds distributed in the Southern Hemisphere. Climate change is a growing problem that affects penguins, especially those living in Antarctica, making them some of the most currently endangered species. Loss of habitat, commercial fishing and infectious diseases spread by anthropogenic activities in the Southern Ocean are threats facing penguins. In addition, environmental changes affect the distribution of free-living species that act as intermediate hosts for parasites (e.g. krill, fish) and consequently their transmission dynamics and distribution. The present work aims to provide an update on macro- and microparasites recorded in all penguin species in wildlife. Based on published records from penguins, we provide a list of 157 parasite taxa recorded in all penguin species. The list includes 54 helminths, 45 arthropods, 39 bacteria and 19 protozoa reported in 207 scientific publications. Most papers were focused on the genus Spheniscus. In the analysis, we identify the distribution of parasites among hosts to better predict the disease risk facing their populations worldwide. Some pathogenic effects of the parasites found are discussed.

During a 2019 Chilean Antarctic Scientific Expedition (ECA 55) studying crustose coralline algae (CCA) diversity on the Antarctic Peninsula, bleaching of these algae was observed for the first time in this region. Here, we present initial findings on the physiological state of bleached and normally pigmented CCA (Clathromorphum sp.) assessed using chlorophyll-a fluorescence induction pulse amplitude modulation. The study site experienced high light exposure and salinity in the water column. Our analyses found that bleached CCA have relatively healthy photophysiology responses but lower photosynthetic efficiency, which could be associated with the low salinities recorded in the study area. However, seasonal monitoring and mesocosm experiments across the southern polar latitudes are urgently required to confirm this hypothesis.

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.

Sub-Antarctic marine life exhibits unique ecological traits and pronounced endemicity levels. Despite their ecological uniqueness and high conservation value, studies on sub-Antarctic benthic communities are scarce. Using underwater video imagery, we assessed the nearshore diversity and structure of faunal and algal communities of the Crozet archipelago along 12 scuba and remotely operated vehicle transects performed at Baie du Marin and Crique du Sphinx (Ile de la Possession). The influence of habitat types on species distribution was evaluated in relation to the setting up of submarine cables. A total of 51 faunal (mainly represented by Echinodermata and Porifera) and 14 algal (mainly represented by Rhodophyta) taxa were identified. The high habitat heterogeneity found in shallow waters (from 0 to 20 m depth) enhances the species richness and diversity, whereas deeper (> 20 m depth) areas were dominated by large sandy stretches and a lower diversity. Rocky habitats had the highest richness and diversity values, promoting local diversity. Submarine cables act as a hard substrate for species, whose suspended sections influence the composition and structure of benthic communities. This study improves our limited knowledge of benthic habitats and diversity from Crozet and constitutes a baseline for further monitoring of marine communities for conservation strategies related to this part of the French Southern Territories National Nature Reserve.

Antarctica is populated by a diverse array of terrestrial fauna that have successfully adapted to its extreme environmental conditions. The origins and diversity of the taxa have been of continuous interest to ecologists since their discovery. Early theory considered contemporary populations as descendants of recent arrivals; however, mounting molecular evidence points to firmly established indigenous taxa far earlier than the Last Glacial Maximum, thus indicating more ancient origins. Here we present insights into Antarctica's terrestrial invertebrates by synthesizing available phylogeographic studies. Molecular dating supports ancient origins for most indigenous taxa, including Acari (up to 100 million years ago; Ma), Collembola (21–11 Ma), Nematoda (~30 Ma), Tardigrada (> 1 Ma) and Chironomidae (> 49 Ma), while Rotifera appear to be more recent colonizers (~130 Ka). Subsequent population bottlenecks and rapid speciation have occurred with limited gene transfer between Continental and Maritime Antarctica, while repeated wind- or water-borne dispersal and colonization of contiguous regions during interglacial periods shaped current distributions. Greater knowledge of Antarctica's fauna will focus conservation efforts to ensure their persistence.

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.

Polar ecosystems are threatened by non-native plants, and this risk will increase with climate warming. Non-native plant growth depends on Antarctic environmental conditions and substrates, but these influences are poorly quantified. Under laboratory conditions we quantified the growth of Holcus lanatus, Trifolium repens and Taraxacum officinale across nine sub-Antarctic and Maritime Antarctic substrates with varying characteristics. This included, among others, variation in carbon (0.2–27.0%), nitrogen (0.03–2.1%) and phosphorus (0.04–0.54%) contents, under simulated Antarctic conditions (2°C) and a warming scenario. Legacy effects from an established non-native chironomid midge (Eretmoptera murphyi) and non-native grasses were included. H. lanatus and T. repens grew best in organic- and nutrient-rich substrates, while T. officinale growth was poorly correlated with substrate characteristics. Warming increased plant size by one to three times, but inconsistently across species and substrates, suggesting that climate change impacts on plant growth will vary across the Maritime Antarctic. A variable response was also observed in the legacy effects of E. murphyi, while non-native grasses increased H. lanatus and T. repens plant size, but not that of T. officinale. Plant growth was positively correlated with substrate organic and phosphorus content, and this information was used to trial a novel approach to identifying sites ‘at risk’ from plant invasions in the Maritime Antarctic.

Recent studies have revealed significant hidden diversity and a high incidence of cryptic speciation in Antarctic marine gastropods. Originally, philinoid cephalaspideans in the Southern Ocean were classified within the genus Philine. However, molecular and morphological studies have shown that three genera encompass all known diversity instead. These are Antarctophiline, Waegelea and Spiraphiline, the first two belonging to the recently erected family Antarctophilinidae. In this study, 55 specimens were collected from the South Shetland Islands, across the South Atlantic Antarctic Ridge to Bouvet Island, and from the South Sandwich Islands and Bransfield Strait, between 134 and 4548 m depth. We conducted morpho-anatomical and phylogenetic analyses to describe two new Antarctophiline species: Antarctophiline abyssalis sp. nov. and Antarctophiline malaquiasi sp. nov. Molecular results support the validity of the two distinct species, consistent with observed morpho-anatomical differences in the digestive system (i.e. the shape of gizzard plates and salivary glands), shell shape and other external characters. Additionally, we evaluate the morphological affinities of the most common Antarctic species, Antarctophiline alata, throughout its distribution range. Overall biogeographical distributions are discussed in a systematic context. Our study is yet another example of how Antarctica keeps revealing itself as a cornerstone of gastropod diversity.

Marambio (Seymour) Island is located in the James Ross Archipelago east of the Antarctic Peninsula. Although several research groups have carried out studies on the biodiversity on the island for decades, surveys of bryophytes have not been developed. That is why there are currently only six species of mosses recorded in the northern part of the island. During the 2021–2022 summer Antarctic field trip, 15 mosses species were surveyed in Marambio Island. Of the total number of collected species, nine are reported for the first time for Marambio Island. For the remaining four species, their distributions are now expanded to Marambio Island.

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.

We report here an isolated insect forewing from Triassic deposits of the Eisenhower Range, northern Victoria Land, Antarctica. Based on the reduced venation (e.g. well-developed pterostigma, Rs dichotomously branched, Rs and M vein with five branches each), we tentatively identify the specimen as belonging to Permochoristidae (Mecoptera). However, due to incomplete preservation of the forewing, we prefer a determination under open nomenclature until more material of this taxon is available. The new specimen represents the first insect described from the Triassic of Antarctica and the first fossil record of Mecoptera in the continent, supporting the worldwide distribution and a greater diversity of the family during Triassic times.

In the sub-Antarctic, where food webs are relatively simple and species richness is low, the introduction of predators can be devastating, as native prey may lack sufficient defences and native predators may be less competitive. Merizodus soledadinus Guerin-Meneville, 1930 is a predatory carabid beetle that has been introduced to two sub-Antarctic islands. This ground beetle is known to threaten native insect populations; however, the full extent of its impacts in its introduced ranges is unknown because of its poorly described dietary breadth. As invasive predator impacts depend strongly on their dietary preferences and behaviour, we performed experiments to study the responses of this beetle to olfactory cues and sub-Antarctic diet. We studied the responses of M. soledadinus to olfactory cues to understand whether this species relies on odour to locate prey or different habitats, but we found no significantly different responses to different stimuli. We found that M. soledadinus attacked and consumed mostly juvenile forms of invertebrates from diverse phylogenetic lineages, indicating that many native species may be at risk from this predator and that attack by multiple individuals increased their success with hunting difficult prey. Our findings reveal that M. soledadinus has a wide dietary breadth, which has probably contributed to its successful establishment in multiple novel communities. We discuss the implications of our results for the ecology and conservation of terrestrial macroinvertebrate communities in its colonized range, where limited options exist to prevent further spread of this invader.

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.

This work provides a comprehensive examination of microplastic air pollution in Antarctica. Due to atmospheric microplastics’ emerging importance, analytical procedures and health effects are discussed. Microplastic pollution poses an increasing threat to the unique and delicate Antarctic ecosystem, potentially triggering harmful consequences not only for the local ecosystem and fauna, but also for human health and well-being, given the severe implications of microplastic pollution for global scenarios such as imminent worldwide warming and the melting of polar ice. Numerous investigations have now exposed the extent of microplastic pollution in the Antarctic and the prevalence of both nano- and microplastics in this region, a significant storehouse of the planet’s freshwater. This work also highlights the challenges of assessing the hazards that microplastics, particularly the nanoscale variants, may pose to human health and life maintenance. The results of this work suggest that global mechanisms of microplastic pollution mitigation are critical to microplastic transportation to the Antarctic reaches. This overview provides a better understanding of microplastic pollution in Antarctica while highlighting the urgency of more comprehensive research in this area to elucidate more precisely the short-, medium- and long-term effects of the arrival of these emerging contaminants in the Antarctic.

The Antarctic active volcano Deception Island has been the subject of extensive geological, geophysical and geomorphological research, including studies on its volcanic history. Since the initial geoscientific research, many authors have included lineament traces (in general considered as faults) in the maps, schemes and figures accompanying their publications. In the last 3 decades, several papers have contributed to improving our understanding of the volcano’s structure. In some cases, the fracture network was identified, measured and analysed and general models of the island’s structure were developed. However, the various authors have not always used consistent methodologies for lineament mapping, presenting significant disparities in the obtained results. This paper analyses previously interpreted lineaments and integrates existing geophysical, geological and morphostructural evidence, along with original field data, to establish a morphostructural model through a coherence and uncertainty analysis. The lineaments determined on Deception Island exhibit three preferred directions: NE-SW, ESE-WSW and SSE-NNW. However, the fractures measured in the field generally show a radial distribution, although there are two preferred directions: NNE-SSW and SE-NW. A synthetic map of Deception Island’s lineaments is presented, indicating which are the lineaments that should be considered tectonic-volcanic fractures among the other existing lineaments.

As a result of analysis of the ice cover, geological structure and tectonics of the underlying rocks in the Lake Vostok area of Antarctica, a layered sub-horizontal structure of the ice cover and a distribution of the parameters of the ice composition were established. The physical and mechanical properties of the underlying rocks were determined experimentally. Complex tectonics revealed an increase in geothermal flow in the Vostok Basin region, which plays a role in the evolution of the Earth's crust and in shaping the morphology of its physical properties. A three-dimensional geomechanical model of the unified system ‘glacier-Lake Vostok-bedrock ’ was constructed and investigated. Regularities in the changes to the stress-strain state were revealed. Zones of development of plastic deformation in the ice cover along the perimeter of Lake Vostok and their distribution over the lake were established, which were confirmed by results from field observations. Modelling of geomechanical processes shows that the change in the mechanical state of the Earth's crust, taking into account the creep deformation of the ice sheet, relates more to nonlinear dynamic systems, which are characterized by unstable changes and should be considered as fractal systems.