The Antarctic plunderfishes Artedidraco lönnbergi and A. skottsbergi are small, bottom dwelling species inhabiting the continental shelf of the High Antarctic Zone. During cruise 97–9 of the US RV Nathaniel Palmer during the summer in the south-western Ross Sea, samples of both species were collected by means of bottom trawling. On the basis of macroscopic and histological analysis, we present the first data on the reproductive characteristics of these two plunderfishes, including gametogenesis, spawning period and absolute fecundity. Histologically, we found immature (stage I and II) and mature (stage V) females in both species, whereas developing females (stage III) were found only in A. skottsbergi. All examined male specimens of A. skottsbergi were in the final stage of spermatogenesis (stage III), whereas male A. lönnbergi were immature (stage I), mature (stage IV) and post-reproductive (stage V) individuals. In both species, spawning takes place in summer during December and January. Absolute fecundity was very low, with less than 100 and 200 oocytes in A. lönnbergi and A. skottsbergi, respectively. These data are compared with those reported in literature for other artedidraconids.

The sulphate ion (SO42-) is one of major species in freshwater as well as seawater, originating from various natural and anthropogenic processes (Krouse & Mayer 2000). Compared to the Northern Hemisphere, where human activities affect the sulphate concentration and isotopic signatures, the contribution of anthropogenic sulphate is likely to be negligible in freshwater and ice cores in the Antarctic region (Patris et al. 2002). This means that the sulphur and oxygen isotope compositions of the dissolved sulphate could hint at information on the sources, formation and deposition due to various natural processes and sulphur cycling in the Antarctic region, especially for the dissolved sulphate in surface waters such as ponds and creeks (Patris et al. 2000, Kim et al. 2017). Here we report the ion concentration and sulphur and oxygen isotope compositions of the dissolved sulphate in freshwater from King George Island in the Antarctic Peninsula, which provide implications regarding the sources of the dissolved sulphate and the sulphur cycling in the Antarctic region.

Global human activities, such as greenhouse emissions and pollution, are promoting global warming, environmental changes and biodiversity reduction. Pristine environments such as those of Antarctica are not immune to these phenomena, as is noticeable from the increasing pace of the temperature shift registered within the continent in recent decades. In this study, we describe the first de novo transcriptome analysis of the endemic Antarctic springtail (= collembolan) Cryptopygus terranovus and we evaluate its global gene expression response following a mid-term exposure of 20 days to 18°C. Expression data are compared with wild specimens sampled from their native environment to outline the molecular mechanisms triggered by the thermal exposure. Although individual plasticity in transcript modulation is assessed, several pathways appear to be differentially modulated in springtails subjected to the heat treatment vs wild specimens. Through enrichment analysis, we show that protein catabolism, fatty acid metabolism and a sexual response characterized by spermatid development are induced, while carbohydrate consumption, lipid catabolism and tissue development are downregulated in treated samples compared to controls.

Two new species of Paramunnidae (Crustacea, Isopoda, Asellota) from the South Shetland Islands (sub-Antarctic) are described. Austrosignum escandellae sp. nov. has long eyestalks, dorsum slightly sculpted (transverse bumps on pereonites 1–5), and lateral margins of pereonites rounded. The closest species is A. spinosum Kussakin, 1982 that also shows dorsum sculpted. The main differences are the ocular peduncle (short in A. spinosum) and the lateral margins of pereonites (pointed in A. spinosum). Coulmannia ramosae sp. nov. differs from the other two species of this genus (C. australis Hodgson, 1910 and C. frigida Hodgson, 1910) in that only the margins of pereonites 2–4 are expanded (into one point). A discussion of the Austrosignum/Munnogonium complex is provided with a comparative table of the species involved.

A detailed stratigraphical, palaeoecological and geomorphological reconstruction of a fjord head on South Georgia (Husvik, Stromness Bay) is presented. Six sites were chosen to reconstruct the lithostratigraphy of the area by means of coring. A maximum depth of 11 m was attained and the sediments encountered vary from coarse gravel over sands to fine silts with, in some cases, intercalated peat layers. Diatom analysis allowed determination of whether the sedimentological units were deposited in a marine or freshwater environment. Six radiocarbon dates constrain the chronology. Deglaciation of the area was completed in the early Holocene and the postglacial geomorphological evolution of Husdal (unofficial name) was controlled by fluvio-deltaic deposition and sea level changes. Relative sea level rise was faster than, or kept pace with the isostatic rebound of the land. Our results challenge the presence of Late Glacial and Holocene raised beach deposits in the area as reported in earlier geomorphological studies.

The current political regime for the Antarctic stemmed from the activities of the non-governmental International Council of Scientific Unions (ICSU) in planning and implementing the IGY (1957–58); subsequently the Antarctic Treaty came into force in 1961. The Treaty promotes freedom of scientific research and international co-operation and in the first two decades of its existence this was an undisputed priority. SCAR, a committee of ICSU, is a non-political organization, which initiates, promotes and co-ordinates scientific research in the Antarctic. SCAR has always attached the highest importance to environmental protection and for over thirty years has readily accepted an advisory role in relation to the Treaty System. One Convention (CCAS on seals) has a built-in advisory role for SCAR - an unusual, probably unique function for an NGO. Another (CCAMLR on marine resources) often seeks advice from SCAR. The success of the Antarctic Treaty System owes much to SCAR.

The waters along the West Antarctic Peninsula (WAP) have experienced warming and increased freshwater inputs from melting sea ice and glaciers in recent decades. Challenges exist in understanding the consequences of these changes on the inorganic carbon system in this ecologically important and highly productive ecosystem. Distributions of dissolved inorganic carbon (CT), total alkalinity (AT) and nutrients revealed key physical, biological and biogeochemical controls of the calcium carbonate saturation state (Ωaragonite) in different water masses across the WAP shelf during the summer. Biological production in spring and summer dominated changes in surface water Ωaragonite (ΔΩaragonite up to +1.39; ~90%) relative to underlying Winter Water. Sea-ice and glacial meltwater constituted a minor source of AT that increased surface water Ωaragonite (ΔΩaragonite up to +0.07; ~13%). Remineralization of organic matter and an influx of carbon-rich brines led to cross-shelf decreases in Ωaragonite in Winter Water and Circumpolar Deep Water. A strong biological carbon pump over the shelf created Ωaragonite oversaturation in surface waters and suppression of Ωaragonite in subsurface waters. Undersaturation of aragonite occurred at < ~1000 m. Ongoing changes along the WAP will impact the biologically driven and meltwater-driven processes that influence the vulnerability of shelf waters to calcium carbonate undersaturation in the future.

Mixing in Ellis Fjord, Vestfold Hills, East Antarctica, is controlled by processes which are influenced by the extent of ice formation. A study of water temperature and salinity at a site near the middle of the fjord was undertaken from May 1994 to February 1995 after a summer (1993–94) in which the ice cover of the fjord was largely retained. Vertical mixing resulting from the exclusion of salt during the limited winter formation of ice was insufficient to mix completely the non-meromictic basins of the fjord. In contrast, a previous study during a winter with far more ice production recorded much stronger vertical mixing throughout the fjord. Warming and freshening of the fjord during the 1994–95 summer, when the ice again did not melt significantly, was attributable to the flow of warmer, less saline water along the fjord. This process was probably related to the formation of tidal jets at the narrow and shallow entrance to the fjord, and was thus influenced by the ice conditions around the entrance. These jets would also have introduced significant amounts of extra-fjord water (along with any resident biota) into the fjord.

The Wilkes Subglacial Basin (WSB), the largest subglacial basin in East Antarctica, is a topographic depression of continental proportions that lies beneath the East Antarctic continental ice sheet. Discovered by the US Victoria Land Traverse 1959–60, the origin of the WSB and the influence of palaeoclimate on its overlying continental ice sheet have remained uncertain since the time of its discovery. Most explanations of origin favour lithospheric structural control as a function of tectonic activity. Lithospheric flexure due to thermally or isostatically induced uplift of the Transantarctic Mountains was suggested in the 1980s. Lithospheric extension and rifting was proposed in the 1990s. More recent investigations have revealed the presence of fold and thrust belts, casting doubt on flexural and extensional hypotheses as the primary mechanisms, suggesting instead a compressional scenario. While remaining inconclusive, these tectonic mechanisms in one form or another, or in combination, are now believed to have provided the structural control for the origin of the WSB. Not yet comprehensively examined, however, is the role of non-tectonic processes in the formation of the WSB, as they may have influenced the size, configuration, subglacial sedimentation and subglacial topography of the WSB. In this paper we review the tectonic hypotheses and examine post-tectonic climate change along with glacial and marine processes as potentially significant factors in the present condition and configuration of the WSB. In the process, we find that there are a number of features not included in previous investigations that may have been major factors in the modification of the subglacial basin.

Visitor Site Guidelines are the principal instruments guiding tourist activities and behaviour at intensively visited sites. These instruments attempt to minimize tourist impacts on Antarctic wildlife, including penguins. However, some recommendations still need to be reinforced by empirical research. Although penguins have enjoyed considerable research attention, a knowledge gap still exists regarding penguins' behavioural responses to realistic tourist activities, including talking sound, viewing distance and movement speed. To fill this gap, we conducted a series of experiments to simulate these activities on two penguin species breeding at an intensively visited site during the 2019–2020 season. We performed 106 replicates of passive and active human presence treatments. Responses varied between species, but active human presence consistently triggered significantly higher responses of strong vigilance behaviour. Our results reinforce Visitor Site Guidelines' recommendations of keeping quiet, moving slowly and increasing viewing distance if changes in behaviour are observed. We also recommend adopting a more conservative viewing distance in the early breeding season. Additional management-orientated empirical studies are needed, including on different species, sites and stages of the breeding season, as such results are valuable for strengthening tourism guidelines and assessing the efficacy of management measures under a post-COVID-19 scenario of increasing Antarctic tourism.

A key element in Antarctic conservation over the past forty years has been area protection. In pursuit of this and the protection of continuing scientific investigations 59 protected areas have so far been agreed by the Antarctic Treaty Consultative Meetings. Although both flora and fauna have been protected under this regime there has only been the habitat matrix devised by SCAR as a guide to selection of areas. What could we do to improve the process of identification and selection?

The first systematic sampling in the Southern Ocean to capture cephalopods took place 120 years ago aboard HMS Challenger. Over the next century taxonomic knowledge was advanced by expeditions including the Mission du Cap Horn (France), the Valdivia Deep Sea Expedition (Germany), the Discovery expeditions (UK) the Eltanin (USA) and Academic Knipovitch (USSR). Over the last decade Southern Ocean cephalopod research has at last progressed beyond the descriptive phase and is rapidly joining other fields of Antarctic marine biology in its concerns with population biology and trophic systems, Although much taxonomic work remains to be done, ecological studies on the role of cephalopods in the diet of predators has been facilitated by advances in the identification of cephalopod beaks, development of opening-closing nets has allowed fine-scale distribution studies, and as methods for the study of growth, diet and biochemical genetics have advanced, so these have been applied to Southern Ocean cephalopods.

Meteoric water that interacted with minerals during retrogressive metamorphism and hydrothermalism in the late-stage of mountain building processes contains hydrogen and oxygen isotopes that are potential proxies for palaeoelevation reconstruction in Antarctica. The effects of temperature on meteoric isotopic signatures, meteoric crustal infiltration processes, and the mechanisms of capture and preservation of meteoric δD and δ18O values in rock-forming minerals are discussed. Special emphasis is given to Antarctica’s geographical high-latitude position and climatic fluctuations over time and to the highmountain ranges of continental Antarctica, which were tectonically active regions in the past. In this context, a new compilation of recent Antarctic snow and ice δD and δ18O data is presented, by which we demonstrate that net elevations versus isotopic depletions are positively correlated for continental Antarctica - a prime requisite when estimating palaeoelevations.