Pringlea antiscorbutica R. Br. (Brassicaceae) and Ranunculus moseleyi Hook. f. (Ranunculaceae) are two species endemic to the subantarctic phytogeographical zone of the south Indian Ocean (Marion and Prince Edward, Crozet, Kerguelen and Heard Islands) (Chastain 1958). The first species is the well-known “Kerguelen cabbage”, and for this taxonomic anomaly a monospecific genus was created (Hooker 1848). The only chromosome count available is by Hamel (1951). The second species Ranunculus moseleyi was first believed to be a strict endemic of the Kerguelen Islands, and then apparently was recorded on Crozet and Marion Islands (Greene & Walton 1975).

Palaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ3) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ3 are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ3 orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

A small freshwater pond near Palmer Station, Anvers Island, (64° 45'S, 64° 05'W) was sampled every 6 h over a 24 h period during the late austral summer to examine changes in both neuston and plankton population levels and activity. Total bacteria using acridine orange and epifluorescence microscopy, counts of viable colony-forming units, and chlorophyll a were determined. Activity was estimated by measuring the rate of 3H-thymidine incorporation. The data indicate that over this time period the bacterioneuston populations went through a diel fluctuation and temperature may be an important factor in this cycle. Although the bacterioneuston populations were often more numerous than corresponding plankton populations, subsurface bacteria appeared to be metabolically more active.

The aim of this work was to investigate the effect of different fractions of UVR on two Antarctic marine bacteria (Arthrobacter UVvi and FCB-related UVps strains) and to study the relationship between the bacterial viability and the UVB dose. Ten experiments exposing strains to natural solar radiation were conducted in Potter Cove, South Shetland Islands. The effect of different UVR wavelengths on viability was analysed by using cultures in quartz bottles covered with interferential filters. Six treatments were performed: DARK, PAR (with UVR shielded off), UVA360, UVA320, UVB305 and UVB280. In all UVR treatments, strains showed significant losses of viability under high and moderate irradiance and no differences were observed between UV treatments. Under high UVB dose (15.0 kJ m−2 received in only two hours), the effect of UVB treatments was significantly higher than that observed under UVA treatments. However, UVA caused a significant reduction on bacterial viability. Survival rates were negatively correlated with integrated UVB dose, FCB-related UVps being more sensitive than Arthobacter UVvi. The similar values observed in viability when the same dose was received in different time periods suggested that DNA repair mechanisms are not much effective in these strains. The different response to the UV wavelength ranges studied here suggests that changes in the spectral composition of natural radiation could differentially affect the components of Antarctic marine bacterial communities.

When scientists from HMS Challenger dredged animals from over 5km depth, they finally laid to rest the azoic hypothesis of Edward Forbes, that life could not exist in cold dark depths of theocean, and thereby opened the doors to true deep-sea biology. The past decade has witnessed a furthersea change in our view of marine diversity, if I may be permitted the pun, a change driven to a largeextent by improved knowledge from Antarctica. For many years we viewed the tropics as the enginesof diversity; species arose in warm clear seas, especially those associated with coral reefs, and spreadslowly to populate the harsher high latitudes. Early studies of the isopod fauna had also suggested thatat least some organisms living on the continental shelf of Antarctica may have originated in the deepsea. After a period of intense work, much of it under the auspices of the SCAR EASIZ (Ecology of theAntarctic Sea Ice Zone) and more recently the EVOLANTA(Evolution in Antarctica) programmes, wecan now modify both hypotheses, with powerful implications for our understanding of global marinediversity. The marine invertebrate fauna of the Antarctic continental shelf is now better described thanmight be thought, and the total fauna may well exceed 17000 taxa. Interestingly, there are very fewplaces in the world with comparable data, but we can say that the fauna has had a long history ofevolution in situ and is not simply a last refuge for taxa that originated elsewhere.

Measurements of snow accumulation are critical for reliable prediction of future ice mass loss and hence projections of sea level change. However, there are currently very few published in situ measurements of snow accumulation in the Pine Island–Thwaites glacier catchment of the Amundsen Sea Embayment, and none from low elevation sites west of 100.77° longitude. Here measurements of snow accumulation over an 11 month period in 2016 are reported for six sites in the Pine Island–Thwaites glacier catchment. The average accumulation rates of 0.10±0.01 to 1.26±0.22 m w.e. yr-1 are comparable with those derived from airborne radar for the period 1985–2009, suggesting very high rates of snowfall, particularly in the vicinity of the grounding line.

Because of its remoteness, Marie Byrd Land is among the most inaccessible and least visited parts of Antarctica. However, it contains a very poorly studied, large Cenozoic alkaline volcanic province and an outstanding record of volcanism coeval with glaciation (LeMasurier & Thomson 1990). This short note describes the results of the second of two planned periods of fieldwork, which form part of the West Antarctic Volcano Exploration (WAVE) project. The background to WAVE and preliminary results of the 1989–1990 fieldwork are described in Smellie et al. (1990) and McIntosh et al. (1990). The studies described here took place between 2 November 1990 and 11 January 1991.

Laccases are enzymes from the multi-copper oxidase family that have gathered a lot of attention due to their wide range of substrates, their interspecies variability and their still elusive mechanism of action. The presence of four copper atoms in their active site makes them an interesting model for the study of the relationship between the structure and function of proteins. It is possible to find them in fungi, plants and prokaryotes. Bacterial laccases display many advantages over fungal laccases in terms of their application. They have, in general, a greater thermal stability and a different pH profile, which contributes to widening their field of possible application. In the present work, a novel laccase from an Antarctic microorganism, Geobacillus sp. ID17, is purified and characterized. This is the first Antarctic bacterial laccase to be functionally described. It was found to be active at neutral pH and to have greater activity at 55°C. Its catalytic constants are in the order of other bacterial laccases. Screening for different potential substrates was also performed, showing that this novel laccase is more selective than commercial laccases. This enzyme could find potential application in the generation of gallic acid polymers or in organic synthesis in contexts where meticulous substrate discrimination is needed.

Alpine-type valley and cirque glaciers occur in many massifs in the northern Prince Charles Mountains. A total of forty-seven glaciers have been investigated using maps and aerial photographs, and in the summer of 1991–92 seventeen of these were examined in the field. The distribution of these glaciers and their present-day snowline line altitudes appear to be influenced by their location with respect to snow-bearing winds, particularly the summer winds that bring moisture from the open waters of Prydz Bay. Moraine morphologies indicate that these glaciers advance and retreat out-of-phase with the larger ice sheet outlet glaciers. During the last glacial maximum the alpine-type glaciers retreated while the ice sheet outlet glaciers showed a minor expansion. This is believed to be due to the alpine-type glaciers being starved of snowfall as the expanded last glacial maximum sea-ice cover around the continent would have removed their maritime moisture sources. Recent contrasts in the behaviour of the alpine glaciers may reflect changes in summer sea ice extent in Prydz Bay.

Like every other continent in the world, Antarctica has been affected by the COVID-19 pandemic, in an imagined as well as a practical sense. Antarctica is a mediated experience; that is, most of us experience the place through films, novels, music, visual arts and the media. We present an analysis of media articles from eight countries over three time periods - pre-COVID-19 outbreak (October–December 2019), shortly after the pandemic hit the headlines (March–May 2020) and when the virus was established (October–December 2020) - to discover how COVID-19 may have changed Antarctic discourse. Our study shows that representations of Antarctica have been affected by the pandemic, in some instances reinforcing existing ideas and in other cases bringing new ideas to the fore. Based on our findings, we believe that COVID-19 has begun to change representations of Antarctica, stepping us away from the prevailing Antarctic hero narrative and providing a more contemporary understanding of the Antarctic experience. We argue that this may increase our motivation to engage with Antarctic issues, with associated implications for future global stewardship of the region.

Chinstrap penguins (Pygoscelis antarcticus) show little sexual dimorphism and sexing by direct observation can be difficult. Through molecular techniques, male and female adults were identified at Stinker Point, Elephant Island, South Shetland Islands, in the 2011–12 and 2012–13 breeding seasons. In the assessment of sexual dimorphism using morphological characteristics, males were 6.0–9.4% larger than females. From the most significant morphological measurements, a discriminant function was formulated that classified 80.6% of the birds correctly. In addition, our data on bill length and depth were compared with those in the literature to evaluate sexual dimorphism between different breeding locations and to test the performance of the discriminant function. There were no differences in sexual dimorphism between breeding locations. However, the discriminant function should be used with caution because some penguins may be misclassified. Therefore, when there is doubt about the accuracy of morphometric approaches, application of molecular sexing techniques is recommended.

Microwave radiometer SSM/I (Special Sensor Microwave Imager) data and scatterometer QuikSCAT (Quick Scatterometer) data have been widely used for near-surface snow melt detection based on their sensitivity to liquid water present in snow. The SSM/I data have high reliability and the QuikSCAT data have high spatial resolution. In order to improve the accuracy of Antarctic near-surface snow melt detection, we propose a new method based on the synergy of SSM/I and QuikSCAT data, i.e. the snow melt physical model incorporates the complementary advantages of both datasets. Based on comparisons with temperature data from three automatic weather stations, the proposed algorithm improved the accuracy of snow melt detection. The algorithm could also be applied to other regions, which would provide further evidence to support its use and additional data to document changes in the Antarctic due to global climate change.

Cetacean fossils have been recorded from middle and late Eocene deposits on Seymour Island since the beginning of the twentieth century and include fully aquatic Basilosauridae and stem Neoceti. Here, we report a small cetacean vertebra tentatively referred to as Neoceti from the late Eocene of Seymour Island. It shows a mosaic of traits, some of which are characteristic of early Neoceti (anteroposteriorly long transverse processes; a ventral keel on the ventral side of the centrum; thin pedicles of the neural arch), whereas others are shared with Basilosauridae (low-placed bases of the transverse processes). However, some traits are unique and may be autapomorphic: presence of separate prezygapophyses on the vertebra at the thoracic/lumbar boundary and a proportionally short centrum. Both traits imply a fast swimming style, which is characteristic of modern dolphins rather than Eocene cetaceans. Thus, this specimen can be identified as Neoceti indet., with some hypothetical odontocete affinities. Along with a few other Eocene whale taxa, it seems to be among the earliest known members of Neoceti on Earth. The finding of small and fast-swimming Neoceti in Antarctica also demonstrates early diversification of cetaceans and ecological niche partitioning by them dating back as early as the late Eocene.

This article is devoted to the assessment of trends of atmospheric air pollution and atmospheric impacts on the environment in the oases of the Thala Hills, Enderby Land, East Antarctica. Estimates of annual emissions of SO2, nitrogen oxides (NOx), inhalable particulate matter with a diameter of ≤ 10 μm (PM10) and CO and their dynamics over 56 years of Thala Hills exploration are given, as well as levels of surface air concentrations of SO2, NOx, PM10 and PM10 atmospheric depositions using air dispersion modelling. It is shown, in particular, that average annual emissions of NOx, PM10 and CO peaked in the early 1990s and have decreased 30.9 times by now. Sulphur dioxide emissions were highest in the late 1960s–late 1970s and decreased 270 times since then. Results of comparisons of modelled air concentrations and depositions with the available data on the measurement of surface air pollutant concentrations and atmospheric depositions are presented. Sources of uncertainties in the estimates of emissions, ground-level concentrations and depositions are described. Proposed approaches can be used to assess the cumulative impacts of ongoing and planned activities on atmospheric air and on other components of the environment through assessing the atmospheric air in the Antarctic Treaty area.

This paper examines two strong or gale-force wind events which began suddenly at Platcha, near the Antarctic ice sheet edge in the Vestfold Hills of East Antarctica, and at a later time were recorded at Davis after progressing slowly across the intervening 25 km of relatively low hills.

In order to continuously monitor the phytoplankton growth in Antarctic coastal waters, an online mooring system was deployed in Great Wall Bay (unofficial name), King George Island, and both chlorophyll a (chl a) concentrations and environmental variables were monitored in a period between December 2010 and March 2011. Water temperatures showed a significant increasing trend (0.27–2.52°C), whereas the salinities displayed a decreasing trend (34.19–33.86). In general, phytoplankton biomass accumulated from mid-December and two significant blooms developed in January (3.18 μg l-1 and 4.75 μg l-1) and were then maintained at a relatively high level, with a transient bloom in late February (4.93 μg l-1). Sea-ice meltwater and terrestrial freshwater input caused by the increase of temperature played an important role in inducing phytoplankton blooms in early summer. The variation and stratification of temperature and salinity signals in different water layers, without total mixing, suggested lateral intrusion of oceanic waters with alternating levels of temperature and salinity and, presumably, phytoplankton as well. Meanwhile, chl a concentrations initially decreased with an increase in irradiance, indicating the shade-adapted characteristic of phytoplankton in early summer, and then gradually adapted to the increasing irradiance. Our results demonstrated the effectiveness and reliability of the online coastal mooring system for the monitoring of Antarctic coastal phytoplankton bloom and environmental conditions.

Throughout the Transantarctic Mountains, Early Jurassic silicic magmatism preceding the emplacement of the Ferrar flood-basalt province (Heimann et al. 1994) is documented by the increasing input of silicic ash into otherwise epiclastic, fluviolacustrine deposits of the Beacon Supergroup (see Elliot et al. 2017). Vertebrate biostratigraphy and radiometric analyses indicate a Sinemurian to Pliensbachian age span for silicic volcaniclastic deposits in the central Transantarctic Mountains (CTMs) (Elliot et al. 2017). For northern Victoria Land (NVL), radiometric geochronology and palynostratigraphy revealed that explosive silicic volcanism began with minor pulses during the early Sinemurian (c. 195 Ma) and reached a peak phase beginning in the middle Pliensbachian (c. 187 Ma) (Bomfleur et al. 2014). A basin-wide correlation of these widely separated age frameworks has so far been hampered by the scarcity of data on coeval deposits in southern Victoria Land (SVL). Here, we present new palynostratigraphic data from mixed epiclastic–volcaniclastic deposits in the Prince Albert Mountains that provide supporting evidence for the widespread synchronicity of silicic volcanic episodes preceding Ferrar magmatism.