An isolated partial right dentary (BAS D.515.2) collected by the British Antarctic Survey prompted a re-evaluation of gadiform remains from the La Meseta Formation (conventionally middle Eocene) of Isla Marambio (Seymour Island), Antarctic Peninsula. Modern gadiforms (hakes and cods) range from the Arctic to Antarctic, inhabiting deep sea benthic, shore, estuarine, and freshwater environments. Based on a fossil record primarily composed of otoliths, they are known to extend back to the Eocene and Oligocene. The new specimen was recovered from the fossil penguin locality D.515. It is characterized by a single row of sharp, ankylosed teeth set upon robust bony pedestals. The surface anterior to the mental foramen exhibits ascending and descending ridges with slightly rugose texture. The ascending ridge is fractured, but partially covers the lateral aspect of the tooth row. BAS D.515.2 is unlike the dentary of macrourid gadiforms, also recovered from the Eocene of Antarctica. BAS D.515.2 preserves several features similar to previously published accounts of the gadiform “†Mesetaichthys” from Isla Marambio. These specimens are probably the same taxon and their combined character suite indicates it is a member of Merluccidae. Thus, these are the only non-otolithic skeletal specimens of an Eocene hake known outside of the London Clay's †Rhinocephalus.

Ozone concentration measurements were made during December from 2001–2005 to quantify the contributions of different processes to near-surface ozone concentrations (O3) in Terra Nova Bay, Antarctica. The average O3 concentration was 20.3 ppbv. On days characterized by high solar radiation fluxes (HSR), significantly higher concentrations of O3 (21.3 ppbv) were recorded compared to days with low solar radiation fluxes (LSR days, 16.8 ppbv). High O3 concentrations could be related to strong winds from SW–NW. Three-dimensional back-trajectories show that air from the interior of the continent could affect O3 at Terra Nova Bay. Moreover, during HSR days, high O3 concentrations were also recorded in connection with weak circulation, suggesting that emissions from the Italian base (located 2 km north) could also represent a significant source of O3. To clarify the role of local pollution in Terra Nova Bay, O3 values were also calculated using the photochemical steady state (PSS) approximation under clear sky and cloudy conditions.

In Antarctica, crabeater seals tend to strand as immature animals with disorientation, due to their inexperience, given as the probable cause. In 2012 and 2013, we examined a group of 80 mummified crabeater seals on Seymour Island (Marambio). The age and gender of 28 seals was determined, and virology and stomach content analyses were performed in order to determine the cause of stranding. Around 82% of the seals examined were adults and 79% were females, some of which were pregnant. All of the seals sampled tested negative for Morbillivirus, suggesting that the stranding was not related to the mass mortality event reported in the 1950s in the region. Most seals had empty stomachs and thin blubber suggesting that they died from starvation. The state of the carcasses suggests multiple stranding events. Most of the seals were located along an ice-covered stream, suggesting that this may act as a ‘natural trap’, isolating the seals from the open ocean. This is exceptional as it is the first report of mostly adult female seals to strand in Antarctica and refutes the theory that only young animals are prone to stranding.

Predictions of the future emperor penguins population, linked to anthropogenic climate change, are stark. Current models suggest that if CO2 emissions continue to rise at present rates, almost all colonies will be quasi-extinct by the end of the century (Jenouvrier et al. 2021). The monitoring of populations is crucial to tracking these changes and, if possible, implementing conservation measures. Recent work using satellite imagery to discover, track and monitor emperor penguin populations has proved to be a key technology in understanding the locations, numbers and trends of the species (Barbraud & Weimerskirch 2001, Trathan et al. 2020, Jenouvrier et al. 2021). It also enables the discovery of unrecorded breeding sites (Fretwell et al. 2009), although there are inherent difficulties in determining what constitutes a new or undiscovered breeding colony (see Supplemental Material S1). In 2019, eight previously unreported emperor penguin breeding sites were found using the European Space Agency's Sentinel-2 satellite, a medium-resolution satellite with a spatial resolution of 10 m per pixel (Fretwell & Trathan 2021), bringing the number of known extant breeding locations to 61. Here, I report on the discovery of a further four breeding sites using Sentinel-2 and Maxar WorldView-2 imagery.

Fluxes of dissolved oxygen and nutrients and vertical fluxes of particulate organic elements were investigated in the subtidal benthic environment of Marian Cove, King George Island, Antarctica, using in situ benthic chambers and near-bottom sediment traps. Fluxes of dissolved oxygen, ammonium, phosphate, and silicate were comparable to those measured in temperate regions. Sediment oxygen consumption was a good indicator of organic respiration and elemental efflux at the benthic boundary layer of Marian Cove, with good positive correlations with ammonia (r2 = 0.67), phosphate (r2 = 0.57), and the C:N:P ratio (106:11.5:1.15) in the chamber water. A positive relationship (r2 = 0.58) between settling particulate organic carbon flux and chl a concentration suggests that water column biomass and production are direct sources of settling particles. According to element budgets in summer assessed using the fluxes, Jin and the sum of Jout and Jburial were 15.9 ± 8.1 and 22.6 ± 8.2 mmol m-2 d-1 for carbon, 2.02 ± 0.54 and 2.46 ± 0.82 mmol m-2 d-1 for nitrogen, 0.07 ± 0.03 and 0.23 ± 0.08 mmol m-2 d-1 for phosphorus, and 12.4 ± 2.7 and 13.5 ± 5.0 mmol m-2 d-1 for silicon, respectively. There was a broad balance between sediment organic input and remineralized output for carbon and nitrogen at the benthic boundary layer of Marian Cove.

In Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do so, we compared mandible morphology in nine species spanning seven families and five functional groups (grazers, suspension feeders, generalist predators, specialist predators and scavengers). Mandible morphology adequately depicted some aspects of amphipod trophic ecology, such as the trophic level at which animals feed or their degree of dietary specialization. On the other hand, links between mandible morphology and amphipod diet were seldom unambiguous or straightforward. Similar adaptations were found in distinct functional groups. Conversely, mandible morphology could vary within a single functional group, and phylogenetic effects sometimes complicated the interpretation of form-function relationships. Overall, mandible morphology on its own was generally not sufficient to precisely predict amphipod feeding strategies. However, when combined with other methods (e.g. gut contents, trophic markers), it constitutes a valuable source of information for integrative studies of amphipod ecological diversity in the Southern Ocean.

Atmospheric carbon monoxide and methane were studied spectroscopically in the Arctic and Antarctic. Seasonal variations of CO are evident in both polar regions, absolute values of abundance being three times larger in the Arctic than in the Antarctic. Increasing concentration trends were confirmed for both gases: 0.8% per year for Antarctic CO, 0.5% per year for Antarctic CH4 and 3.1% per year for Arctic CH4.

New outcrops of Hope Bay Formation and Larsen Basin rocks have been exposed by recent ice-retreat on Tabarin Peninsula, northern Antarctic Peninsula. Quartzose, very low-grade metasedimentary rocks, cropping out at Balegno Nunatak (63°28′53″S, 57°00′31″W) are assigned to the Permian–Triassic Hope Bay Formation, and dioritic rocks are assigned to the Antarctic Peninsula batholith. Sedimentary rocks exposed at Rubulis Nunatak (63°30′52″S, 57°07′29′W) closely resemble Lower Cretaceous sedimentary rocks cropping out at nearby Troilo Nunatak, western Tabarin Peninsula. These rocks are correlated with the lower Gustav Group (?Barremian–Coniacian) of the Larsen Basin. This new record confirs that the Larsen Basin extends over southern Tabarin Peninsula, where basin sediments are thought to be faulted against sediments of the Antarctic Peninsula magmatic arc.

At Pitt Point, the east coast of Graham Land (Antarctic Peninsula), the Early to Middle Jurassic (Toarcian–Aalenian) rhyolite dykes form two coevally emplaced NNE–SSW and E–W trending sets. The nearly perpendicular dyke sets define a large-scale chocolate-tablet structure, implying biaxial principal extension in the WNW–ESE and N–S directions. Along the nearby north-eastern slope of Mount Reece, the WNW–ESE set locally dominates suggesting variations in the direction and amount of extension. Magnetic fabric in the dykes, revealed using the anisotropy of magnetic susceptibility (AMS) method, indicates dip-parallel to dip-oblique (?upward) magma flow. The dykes are interpreted as representing sub-volcanic feeder zones above a felsic magma source. The dyke emplacement was synchronous with the initial stages of the Weddell Sea opening during Gondwana break-up, but it remains unclear whether it was driven by regional stress field, local stress field above a larger plutonic body, or by an interaction of both.

Landforms of Marine Plain in the Vestfold Hills contrast with those of most in the Vestfold Hills. They include consistent land surfaces at 40+ m and 25 m, characteristics controlled by orientation of rock features, and imprints of phases of glaciation, deglaciation and marine and freshwater inundation. The 40+ m surface is widespread in the Vestfold Hills and has been noted previously. The 25 m level was an earlier coastline, is more localized and marked by water rounded boulders; it serves to differentiate clearly between two terrains of different relief and erratic distribution. The Pliocene sedimentary rocks below the 25 m level have been dislocated, probably during an interval of glaciotectonism caused by northward movement of sediments under an ice load due to northern extension of the Sørsdal Glacier or expansion of the East Antarctic Ice Sheet some time after the mid-Pliocene. Soil development is active. These features are accompanied by the normal aspects of a glaciated landscape such as glacial striations, sand wedges, erratics, and patterned ground. Wind has been important in transporting sand and developing honeycomb weathering on exposed rock faces.

Proteases are widely used in industrial processes, and the discovery of new, more kinetically efficient proteases can have a positive impact on industry. Enzymes from Antarctic microorganisms exhibit cold-adaptive properties, making them useful in biotechnology. The cold and harsh environment of Antarctica makes it a valuable source for new biotechnologically related enzymes. In this study, we characterized two cold-adapted proteases purified from Pseudoalteromonas issachenkonii P14M1-4 and Flavobacterium frigidimaris ANT34-7, isolated from King George Island, Antarctica, and compared these with proteases from the non-cold-adapted bacteria Bacillus licheniformis and Geobacillus stearothermophilus. The best temperature growing conditions were used for protease purification and characterization. The protease from P. issachenkonii P14M1-4 was identified as a 40–43 kDa metal-dependent subtilisin-like serine protease and the protease from F. frigidimaris ANT34-7 was identified as a 28 kDa metalloprotease. The enzymes showed an optimum temperature of between 35°C and 40°C and an optimum pH in the neutral to alkaline range. Their activation energies, catalytic constants and growth capacities at different temperatures categorize them as cold-adapted enzymes. We conclude that the characteristics exhibited by these proteases make them useful for biotechnological purposes requiring high activity at low temperatures. Moreover, to the best of our knowledge, this is the first characterization of a cold-adapted protease from F. frigidimaris.

This study investigates the microclimate and hydrology of debris-laden ice surfaces in the Taylor Valley, Antarctica, in early summer, focusing on the onset of melt. Measurements of energy and mass fluxes were made on an outwash fan and in moraines near the terminus of Taylor Glacier. The surface microclimate was strongly controlled by absorbed solar radiation, with a low albedo of 0.17. Seasonal warming of the substrate led to an abrupt shift in thermal and hydrological patterns as temperatures exceeded freezing point. Within a week the Bowen ratio switched from 2.05 to 0.48 and mass losses to the atmosphere increased four-fold from 0.39 to 1.6 mm d-1. Melt onset also produced complex ground temperature patterns with strong diurnal damping below the freezing front. These patterns were caused by phase changes in the freezing front, coupled with an abundant water supply from local runoff. Of secondary importance to the surface energy balance and mass fluxes was the effect of local winds on boundary layer characteristics. This resulted in larger mass losses during the more turbulent, warmer and drier down-valley flows.

The risks posed by a range of acoustic scientific instruments were assessed by the construction of matrices of scale and likelihood. We recognized six levels of impact ranging from none or short term, minimal behavioural response (Level 1) to multiple injuries and fatalities and/or compromised populations (Level 6) and six levels of likelihood ranging from “Expected in almost all instances” (Level 1) to “cannot see how it could happen” (Level 6). Typical scientific instruments ranging from acoustic releases to large air gun arrays were assessed. To provide a perspective for the risks of scientific operations, other activities were also ranked. These included large chemical explosions, submarine detection sonars implicated in some mass strandings of cetaceans and normal Antarctic shipping activities. The conclusion reached was that most scientific instruments pose a similar or lower risk than normal shipping operations. High source-level equipment poses some risk to individual animals' hearing and so should be mitigated. Likewise, survey planning should be designed to avoid trapping animals in narrow, constricted sea ways. Long term, cumulative impacts are still difficult to detect in areas with greater anthropogenic noise than the Antarctic but we concluded that any possible long term impacts should be mitigated by maintaining the low levels of activity using high source-level equipment through data sharing and survey planning.

The shape (derived from landmark-based geometric morphometrics), condition (Fulton index) and diet (determined through gut content analysis) were described for the pike icefish Champsocephalus esox (Channichthyidae) from Última Esperanza sound, south-west Patagonia, Chile. Based on the length-weight relationship, females were heavier at length than males. Nevertheless, the Fulton index was similar between males and females. The morphospace of C. esox showed high intraspecific variability in the dorsoventral position of the tip of the snout, anus and the ventral insertion of the pectoral fin, as well as the anteroposterior position of the premaxilla, opercle and anus. This indicates the existence of phenotypic plasticity, leading to specimens with larger jaws and heads but shorter trunks, or specimens with shorter jaws and heads but larger trunks. This phenotypic plasticity was independent of size and sex. The feeding incidence was similar between sexes (34.1% and 47.2% for males and females, respectively). Diets consisted of only fish, small notothenioids of the genus Patagonotothen (P. tessellata, P. cornucola and P. sima), showing similarities between males and females. Finally, C. esox is the second notothenioid species, and the first outside of Antarctica, to display phenotypic plasticity in its body shape.

Following a report of supposed fragments of calcareous dinoflagellate cysts from a Pleistocene drill core (CRP-1) recovered in the Ross Sea, Antarctica, sediments of the same core were re-investigated for their microfossil content. Besides common foraminifera and other microfossils, rare complete cysts of calcareous dinoflagellates were found. All cysts belong to the species Caracomia arctica (Gilbert & Clark, 1983) Streng, Hildebrand-Habel & Willems, 2002, a taxon characteristic of late Neogene high latitude, coldwater environments. Two morphotypes can be distinguished, C. arctica f. arctica and C. arctica f. rossensis, of which the latter is described as a new form. The presence of C. arctica strengthens diatom-based palaeoenvironmental reconstructions of periodical sea ice-free conditions at the time of deposition. Accordingly, cysts of C. arctica are interpreted as resting cysts that allow survival during harsh intervals of the high latitude environment. Previously reported calcareous dinoflagellates cyst fragments from these sediments are re-interpreted as test fragments of bilamellar foraminifera, which represent the most common group of foraminifers in the sediments.

We carried out a study to investigate the presence of some protozoan parasites (Cryptosporidium sp., Giardia sp., Toxoplasma gondii) on three species of Antarctic penguins: Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua) and chinstrap (Pygoscelis antarctica) from different locations along the Antarctic Peninsula and the South Shetland Islands. Swabs and faeces samples were analysed by PCR assay for Cryptosporidium sp. and Giardia sp. while Toxoplasma was studied using serological methods from blood samples. We did not detect the presence of these organisms in the species studied. However, based on the upper values of the confidence intervals of the observed prevalence, their presence cannot be completely excluded.

We performed an artificial pool experiment in the Antarctic multi-year land-fast ice to examine and simulate the effect of sea ice melting on physical and biogeochemical components of the sea ice field. The input of snow and ice meltwater resulted in warmer, low salinity water at the surface of the pool and probably stratification of the less dense water. Current speed measurements also pointed to water stratification within the pool. Rapid phytoplankton growth in the pool resulted in drastic decreases in concentrations of dissolved inorganic carbon and nutrients (NO3- and Si(OH)4) in the surface waters of the pool, particularly depleted for NO3-. There was high correlation between variations of dissolved inorganic carbon and nutrient concentrations, but the apparent uptake ratios of these components deviated from that generally applied to marine phytoplankton. The sequence of changes in the physical and biogeochemical components of the pool water suggests that the onset of rapid phytoplankton growth was closely related to the water stratification, which provided stable conditions for phytoplankton bloom even though the supply of nutrients from under-ice water would have declined.