Contrary to earlier beliefs, crustaceans are present in ice-covered lakes of Antarctica. Interpretation of the significance of this has been hampered by the absence of robust identification of taxa present. We examine cyclopoid copepods from three widely separated lakes. All belong to the michaelseni group of the genus Diacyclops, which is widespread across Continental Antarctica, but do not fit into any existing species. Two new species were identified from eastern Antarctica, D. walkeri from Pineapple Lake (Vestfold Hills) and D. kaupi from Transkriptsii Gulf (Bunger Hills). Most significant was a dense population of a new epibenthic species (D. joycei) associated with microbial mats in Lake Joyce, one of the smaller McMurdo Dry Valleys lakes. This represents the first record of adult cyclopoid copepods from the ice-covered lakes of the Transantarctic Mountains. Continental Antarctica is the centre of diversity for this group of crustaceans and we argue that this is better explained by persistence through past glacial advances rather than by recent post-glacial colonization. The existence of a species endemic to Lake Joyce but apparently absent from other Dry Valleys lakes is discussed in relation to our understanding of the history of the McMurdo Dry Valleys lakes and their faunas.

The ecological drivers underlying breeding performance are expected to differ across the geographical range of seabird species, but few studies have compared trade-offs between colonies with different local conditions. During chick-rearing (2000–01), we compared the foraging trips, diet and breeding parameters of two Adélie penguin colonies in the Ross Sea, at Edmonson Point (EdPo; ~2000 breeding pairs) and Inexpressible Island (InIs; ~24 000 breeding pairs). Penguins from InIs travelled farther and performed longer feeding trips. The quantity of food brought to the nest was the same for the two colonies, but penguins from InIs brought more fish and less krill. Eggs hatched earlier at EdPo. Breeding success did not differ, but chick weight during hatching–fledging was greater at InIs. Despite worse weather conditions at InIs, the larger proportion of high-energy food brought by penguins from InIs (i.e. fish) may explain their offspring‘s better performance. In addition, the persistence of fast ice at EdPo may have led to greater energy expenditure of breeding individuals, possibly reducing chick growth. The greater intraspecific competition expected at InIs may have been reduced by longer foraging trips and/or counteracted by the more nutritious diet. Our findings reveal complex trade-offs between foraging effort and environmental constraints in determining the breeding performance of Adélie penguins.

The Antarctic terrestrial ecosystem is relatively simple and has low plant diversity. Taking into account the current effects of climate change and the exponential increase in visitors during the past 50 years, this ecosystem is very vulnerable to the arrival of non-native species. Fildes Peninsula, King George Island, is an area of high human impact due to the scientific and logistical activities that occur there making the area particularly interesting for the arrival of non-native species. In this study, we determine the spectrum of seeds arriving to the peninsula and being deposited in the topsoil. Soil samples were collected and analysed in order to identify and quantify plant material. The results indicate that there is a direct relationship between the sites where seeds were found and areas with higher levels of human activity on the peninsula. Eight species were identified, with the most common being Hypochaeris radicata and Senecio jacobaea. Seed quantification indicated that areas of high human activity are most vulnerable to the invasion and establishment of non-native species. This study is the first to demonstrate the presence of non-native seeds in the topsoil at Fildes Peninsula, Antarctica.

Continental freshwater lakes of Antarctica are characterized by species-poor biota (Heywood 1977). The plankton is dominated by algae, bacteria and protozoa (Koob & Leister 1972, Parker et al. 1982, Laybourn-Parry et al. 1991). Three species of micro-crustacea have been reported from Eastern Antarctica, the cladoceron Daphniopsis studeri, Ruhe and two copepods, Acanthocyclops mirnyi, Borutsky & Vinogradov, and Boeckella poppei, Mrazek (Borutsky & Vinogradov 1957, Akatova 1964, Bayley & Burton 1993). The origin of D. studeri in lakes of the Vestfold Hills has been documented (Laybourn-Parry & Marchant 1992) and it is generally thought that populations are derived from subantarctic islands and mainland South America. Populations of D. studeri from three freshwater lakes of the Vestfold Hills, have been studied in more detail in a preliminary survey of its occurrence and basic life cycle (Laybourn-Parry & Marchant 1992) during which it was observed that the population consisted entirely of parthenogenic females appearing to produce only subitaneous eggs. Herbert (1981) reported that some Arctic and Antarctic cladocerans were capable of producing ephippial (wintering) eggs asexually. D. studeri also occurs in some of the brackish lakes of the Vestfold Hills with salinities of <4 ppt. These populations were found to possess male individuals (J. Gibson, personal communication 1991) suggesting a sexual cycle and production of resting eggs. There is no evidence of this in the freshwater lakes of the region.

The Mesozoic-Cenozoic volcanic arc of the Antarctic Peninsula is represented on Adelaide Island by a sedimentary and volcanic succession intruded by plutons. 40Ar-39 Ar step-heating age spectra have been obtained from volcanic rocks and hornblende separates from sedimentary clasts of plutonic origin. These spectra show evidence for some argon loss, but, in general, have plateau ages which are consistent with the mapped stratigraphy and with other geochronological controls, suggesting that they approximate to original ages. As a result the following events in the evolution of Adelaide Island can be recognized:

1) mostly marine Mesozoic sedimentation, 2) Early Cretaceous (c. 141 Ma) plutonism (recorded in clasts from conglomerates), 3) Cretaceous volcanism, 4) Late Cretaceous (possibly Tertiary) sedimentation, 5) Early Tertiary volcanism, which was acidic in eastern outcrops and intermediate elsewhere, and 6) Eocene intermediate volcanism and deposition of arc-derived conglomerates. Volcanism was possibly coeval with known Palaeocene-Eocene plutonic activity on Adelaide Island (part of the Antarctic Peninsula Batholith) and with volcanism of similar age in northern Alexander Island and the South Shetland Islands. The volcanism on Adelaide Island and the South Shetland Islands, at least, was associated with a westward migration of the Antarctic Peninsula arc.

Deception Island is an active volcano located in Bransfield Strait. Its volcanic activity is linked to the presence of gravity anomalies that influence the definition of the geoid. In this paper, a precise undulation geoid model (GeoiDEC14) has been computed from GPS, gravimetric and levelling measurements. GeoiDEC14 highlights local anomalies of the island that match with hot spots, such as the minimum values shown in Fumarole Bay and Whalers Bay (fumarole areas), or the maximum values found in the remains of lava at Colatinas, Black Glacier and Murature Point. Comparison of GeoiDEC14 with global models always shows negative values due to an average of 18.80 m for our model compared to 19.80–20.60 m for models such as ITSG-Grace2014s, EGM08, AIUG-Grace03s or EGM96. This difference is due to the lack of resolution of global models and to the volcanic activity on the island. To confirm the results, the same measurements were taken on nearby Livingston Island. The values of geoid undulation on this island reaffirm the lack of detail in the global geoid in the area, presenting an average of 18.90 m, similar to the average value of GeoiDEC14.

An allochthonous block of the Nordenskjöld Formation from north-west James Ross Island, Antarctic Peninsula has yielded a diverse marine palynoflora. Dinoflagellate cyst assemblages from the 185 m thick sequence are described and compared with similar microfloras previously described from Australia, Papua New Guinea and Madagascar. A mid Tithonian (Late Jurassic) age is suggested for the section. One new genus, Helbydinium gen. nov. and four new species, Helbydinium scabratum sp. nov., Leptodinium acneum sp. nov., Leptodinium posterosulcatum sp. nov. and Rhynchodiniopsis foveata sp. nov. are described.

The Trinity Peninsula Group (TPG) of northern Graham Land, a weakly metamorphosed thick sequence of predominantly quartz- and feldspar-rich greywacke, has tentatively been correlated with metasedimentary rocks exposed along the Bowman Coast of Graham Land (Stubbs 1968). The base of the TPG is not observed but the Bowman Coast rocks, here newly defined as the Bowman Coast Succession (BCS), is proximal to high-grade gneisses, which may represent the local basement. Recent geological mapping along the Bowman Coast has allowed a revision of the local geology (Fig. 1) and this note focuses on the relationship of the BCS with the adjacent gneisses.

Fossil diatom-bearing marine sediment cores recovered from Prydz Channel, Prydz Bay, record episodes of glacial advance and retreat in the bay. Diatom frustules are abundant, well preserved, and the species composition is diverse in two biogenic sediment units composed of siliceous diatom ooze (SMO-1 and SMO-2). Between SMO-1 and SMO-2 a terrigenous unit (T) is present, composed of muddy diamicton and sandy silty clay, which contains poorly preserved rare diatoms. The SMO units are interpreted to represent an open marine setting with seasonal sea ice cover; the T unit is interpreted to represent glacial ice expansion from the Amery Ice Shelf over the site. Based on an age model developed previously for other cores from Prydz Channel with analogous stratigraphies, we interpret our record to be late Quaternary through Holocene in age. The T unit records the Last Glacial Maximum (LGM) in Prydz Bay; the SMO-1 and SMO-2 units record interstadial episodes that are post- and pre-LGM respectively. Extinct diatom taxa in the T and SMO-2 units indicate reworked sediment sourced from two different-aged deposits. Our results provide both a new interpretation of late Quaternary deposition in Prydz Channel and support for previous studies in this region.

Myxomycetes (plasmodial slime moulds) are best known from temperate and boreal forests, where they are commonly found in association with decaying coarse woody debris and leaf litter on the forest floor (Martin & Alexopoulos 1969). There have been only a few reports of myxomycetes from either the continent of Antarctica or the subantarctic islands. In what apparently represents the first record of a myxomycete from the south polar region, Horak (1966) described a new species, Diderma antarcticolum Horak, from material collected on the Antarctic Peninsula (64°53′S, 62°53′W). Later, Ing & Smith (1980,1983) reported Didymium dubium Rost., Lamproderma arcyrioides (Sommerf.) Rost., Stemonitopsis (Comatricha) subcaespitosa (Peck) Nann.- Brem. and Diderma niveum (Rost.) Macbr. from South Georgia (54–55°S, 36–38°W). They also indicated that the latter species was known from Signy Island, South Orkney Islands (60°43′S, 45°36′W) and the Antarctic Peninsula (65°16′S, 64°08′W) as well as South Georgia.

The temporal changes in dissolved inorganic (DIC) and organic carbon concentrations (DOC) were monitored from late autumn to spring 2006 in the Scholaert Channel, West Antarctic Peninsula. Surface DIC spanned a small range (2163.3 to 2194.5 μmol kg-1), increasing from late autumn to winter and then decreasing in spring. An excess of DOC (7.0–63.6 μmol l-1), against a deepwater background concentration of 44 μmol l-1, existed in the surface mixed layer throughout the sampling period. Mass-balance budgeting indicates that the DIC dynamics were primarily governed by remineralization in winter and by primary production in spring despite very low biomass of both autotrophic and heterotrophic organisms. The net community production (7.3 mmol C m-2 d-1) in spring was mainly partitioned to DOC accumulation (3.6 mmol m-2 d-1) and downward export of particulate organic carbon (POC) (2.9 mmol m-2 d-1) rather than POC accretion (0.8 mmol m-2 d-1) in the surface mixed layer. The study area acted as a source of CO2 to the atmosphere in winter (∼0.8 mmol m-2 d-1) and a sink in spring (2.3–5.3 mmol m-2 d-1), and hence was not a one-way CO2 sink as had been previously hypothesized for marginal sea ice zones.

In this study, we aim to analyse the glacier dynamics of land-terminating glaciers in King George Island (Antarctica) between 1956 and 2018. Glacial fluctuations are estimated using space-borne remote sensing data (SPOT, Landsat, PlanetScope, Sentinel-1, Sentinel-2, WorldView-2 and TanDEM-X). The eastern sector of Warszawa Icefield witnessed continuous glacier retreat during 1979–2018 (surface loss of 30%). The decreases in the ice-covered areas of the Tower, Windy, Ecology, Baranowski and Sphinx glaciers were 70%, 31%, 25%, 25% and 21%, respectively, with their accumulation area ratios (AARs) exhibiting negative mass balances. The winter air temperature was cooler during the 1970s with warming trends in the 1980s and early 2000s followed by a cooling trend until the present day. However, the annual time series has shown high interannual variability in air temperature during these periods. We show that the AAR, dimensions, length, frontal elevation, maximum elevation, slope and changes in the terminus position influence the glacier response to climate change at various timescales. Furthermore, three geomorphic activity intensity zones and a complete paraglacial sequence are identified while contrasting the proglacial systems. Overall, subglacial deposits predominate and indicate that meltwater flows on the bed, producing wet-based thermal regimes.

Semi-continuous, linear accumulations of poorly-sorted debris are present on the surface of the remnant Larsen-A Ice Shelf, Antarctic Peninsula. These accumulations form a complex of debris bands extending parallel to the front of the ice shelf for several kilometres. Landsat imagery shows that the debris bands originated as lateral moraines along the Nordenskjöld Coast. Almost 80% of clasts sampled from these debris accumulations have shape/roundness characteristics consistent with glacier transport in the zone of basal traction. Angular and very angular clasts account for 15% and 22% of clasts in the pebble- and cobble/boulder-sized fractions, respectively, and originated by rockfall from valley/nunatak sides, with subsequent passive glacier transportation. Lithological analysis indicates that the debris is derived locally from the Nordenskjöld Coast, Cape Fairweather region and interior of the Antarctic Peninsula. Episodic melt-out and resedimentation of this debris from the front of the ice shelf would deliver pulses of coarse-grained sediment to the sea floor. Therefore, coarse-grained debris can also be released along the calving margin of small polar ice shelves fringing mountainous terrain, and could potentially be confused with sediment deposited at the grounding line of Antarctic ice-shelves. Sedimentological criteria to differentiate between these environments are proposed in this paper.

Large glacial boulders, up to several metres in diameter, resting on the lake ice are a remarkable feature of Lake Untersee (71°21'S, 13°28'E), an ice-dammed, perennially frozen freshwater lake in the Ottovon-Gruber-Gebirge (Gruber Mountains) of central Queen Maud Land, East Antarctica. A geodetic survey of such ice-rafted boulders was made over two summer seasons to determine the direction and velocity of their movement. They are transported between 3.9 and 11.1 m annually and the residence time of the boulders is estimated at approximately 500 years. Lake Untersee must have been permanently covered with lake ice for at least that long.

Many lichens have extensive distributional ranges covering several climatic zones and are able to colonize extreme habitats, including high alpine and polar regions. Cladonia borealis, one of the dominant lichen species on King George Island, is a cosmopolitan species inhabiting polar, subpolar, and alpine areas. It is usually found on soil, humus, and mosses, and is morphologically highly diverse. To understand the phylogeographic history of C. borealis on King George Island, we compared specimens from there with specimens from Norway and Chile. We conducted phylogenetic and haplotype network analyses of the partial SSU, ITS1-5.8S-ITS2, and partial LSU rDNA sequences including intron sequences in LSU rRNA genes. Nuclear rDNA locus of C. borealis from King George Island was separated into two monophyletic lineages. It is suggested that they originated in multiple independent introduction events after long-distance dispersal from other continents.

In austral summer 2004 benthic macrofauna was sampled along a latitudinal gradient along the northern Victoria Land coast (Ross Sea). An Agassiz trawl was used for semi-quantitative data collection of macrozoobenthos at depths from 84 to 537 m. Multivariate analysis of abundance of higher taxonomic units discriminated between the four sample sites along the latitudinal gradient. A SIMPROF analysis emphasized these geographical clusters, as the samples showed no significant differences within each cluster. A change in community structure with depth was not observed. The dominant taxonomic groups along the Victoria Land coast were Echinodermata (39%), Arthropoda (24%), Polychaeta (14%), and Mollusca (12%), not accounting for colonial organisms. Thus, the overall structure of the benthic community off the Victoria Land coast is comparable to other Antarctic regions and shows a closer relationship to the eastern Weddell Sea shelf, which may be attributable to the extensive impact of grounded ice affecting both areas.

Allozyme differentiation was investigated at 23 putative enzyme coding loci in 16 ommastrephid squids to identify species and to assess genetic relationships. The species examined were Illex illecebrosus, I. coindetii, I. argentinus, Todaropsis eblanae, Todarodes sagittatus, T. angolensis, T. filippovae, T. pacificus pacificus, Nototodarus sloanii, N. gouldi, Martialia hyadesi, Ommastrephes bartramii, Sthenoteuthis pteropus, S. oualaniensis, Eucleoteuthis luminosa, and Dosidicus gigas. A dendrogram based on Nei's genetic distance between the species closely approximates to the latest systematics based on morphological characters, but the positions of M. hyadesi and T. eblanae were considerably distant from all other species. The results demonstrate the benefits of further biochemical analysis to an understanding of the systematics of the ommastrephid squids.

A fine-scale survey of the distribution of free-living terrestrial arthropods in the Stillwell Hills region of Kemp Land, East Antarctica, was carried out between 22 December 1996 and 27 January 1997. Three species, all Acari, were recorded: Protereunetes maudae Strandtmann, Nanorchestes triclivatus Booth and N. lalae Strandtmann. Population densities varied from 0 to 6802 ind. m−2 with a mean of 954 ind.m−2. The favoured microhabitat was found to be beneath stones in damp locations on north- and west-facing slopes. Sites with microalgal growth supported more microarthropods than sites with mosses, lichens and macroalgae. Arid and saline habitats, including such sites as wind-sweptridges and the seashore, were found to lack microarthropods. Thermal and humidity profiles above and below the ground surface were recorded to investigate the microenvironments of Acari. Special attention was focused upon the moderating role of snow thickness, vegetation cover, aspect and vertical depth in the soil profile. These microclimate data suggest that Acari are able to avoid the extremes of low temperature experienced at macroclimate level but that heat stress and desiccation may play important limiting roles.

The direction and velocity of iceberg drift were measured during 1987 by photogrammetric methods. Drift along the southern coast of King George Island followed the NE and ENE directions of wind and water currents. The highest mean velocities (0.6–0.8 ms−1) were recorded in March and April, and the lowest velocities (0.1–0.2 ms−1) in winter, from May–July. From August–October velocities (0.4–0.6 ms−1) were higher than in November to December (0.4–0.5 ms−1). The waters flowing into Admiralty Bay came from the western part of the Bransfield Strait.