Chemically defended benthic macroalgae that dominate shallow, hard bottom communities along the western Antarctic Peninsula support very high densities of mesograzers, particularly amphipods but also small gastropods. Previous studies have demonstrated that the macroalgae and amphipods form a mutualistic relationship. The chemically defended macroalgae provide the amphipods with a refuge from predation while the macroalgae benefit from the amphipods greatly reducing surface fouling by smaller algae. One of the three most important macroalgae in terms of overstory cover, Himantothallus grandifolius, forms huge blades that can carpet the benthos. Field observations suggest that gastropods may be higher in relative abundance in proportion to amphipods on H. grandifolius than on other overstory macroalgae. The present study documents the finding that natural abundances of gastropods on H. grandifolius maintained in mesocosms reduce fouling by microscopic algae, primarily diatoms. However, amphipods are probably also important in keeping the macroalga clean of diatoms in nature. In a smaller scale experiment, three gastropod species were differentially effective at reducing diatom coverage on H. grandifolius. The hypothesis that gastropods benefit from associating with H. grandifolius in potentially gaining a refuge from sea-star predation was also tested but not supported by the experimental results.

Haemoglobin carries oxygen from the environment to tissues; in vertebrates, it is contained in specialized cells, called erythrocytes. Over the last century, the study of the chemical properties of this haemoprotein has provided a wealth of information. One of its most important and ancient physiological features is the Root effect, found in many teleost fish (and some amphibians). The Root effect corresponds to an extreme pH sensitivity and can be described as an exaggerated Bohr effect: it dictates to what extent the oxygen tension can be raised in acid-producing tissues. It is likely that the eye choroid rete represents the most ancient anatomical structure associated with the presence of Root effect haemoglobins. This review describes our overall understanding of the molecular properties, biological occurrence, physiological role and evolutionary origin of Root effect haemoglobins. The current knowledge of the structural properties of Root effect haemoglobins is discussed in the light of recent results obtained on the haemoglobins of the coldadapted notothenioids Trematomus newnesi and T. bernacchii.

The temporal and spatial variability of oceanographic properties in Potter Cove was analysed for the 2010–17 summer periods. This was linked with meteorological parameters and sea ice. The water column structure presented significant differences in turbidity between two areas (away from and closer to the Fourcade Glacier). The recent retreat has been transforming it into a land terminating glacier. Therefore, correlations obtained between oceanographic properties near the glacier and meteorological parameters reveal that atmospheric conditions are the main forcing of the Potter system, in agreement with previous studies. Also, high turbidity values within deeper waters in 2013 and 2014 were probably related to resuspended glacial sediment input into the cove. Interannual variability observed in the local parameters was connected to ENSO and SAM, reflecting a larger connection with ENSO, mainly in longer timescales. Colder waters during the 2010 and 2016 El Niño phases could be related to lower air temperature. In summer 2010 during a negative SAM phase, colder, more saline and low turbid waters were observed. Alternatively, in 2012 during La Niña and positive SAM, warmer, fresher and more turbid conditions were found with high vertical stratification. Finally, during 2015 (positive SAM), warmer and low salinity waters were observed.

The soils of the McMurdo Dry Valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain active biological communities that contribute to the biogeochemical processes. We have used ester-linked fatty acid (ELFA) analysis to investigate the effects of additions of carbon and nitrogen in glucose and ammonium chloride, respectively, on the soil microbial community in a field experiment lasting three years in the Garwood Valley. In the control treatment, the total ELFA concentration was small by comparison with temperate soils, but very large when expressed relative to the soil organic carbon concentration, indicating efficient conversion of soil organic carbon into microbial biomass and rapid turnover of soil organic carbon. The ELFA concentrations increased significantly in response to carbon additions, indicating that carbon supply was the main constraint to microbial activity. The large ELFA concentrations relative to soil organic carbon and the increases in ELFA response to organic carbon addition are both interpreted as evidence for the soil microbial community containing organisms with efficient scavenging mechanisms for carbon. The diversity of the ELFA profiles declined in response to organic carbon addition, suggesting the responses were driven by a portion of the community increasing in dominance whilst others declined.

In the Bunger Hills, mapping of glacial drift sheets and examination of striae patterns and other palaeo-ice flow direction indicators show that the largely ice-free region records the imprint of ice sheet expansion(s) during the late Cenozoic. In particular, ice moulded features and striae in southern Bunger Hills suggest formation during at least two episodes of ice sheet expansion, although whether they were formed during separate events or merely different phases of the same expansion of the ice sheet is not able to be discerned at present. The older event relates to thin ice with flow constrained by the topography, whilst the younger event relates to regional expansion of thick ice across the area. Discrimination of the order of emplacement of the cross-cutting striae patterns is possible at a number of sites. Palaeo-ice flow indicators confirm that ice sheet expansion over southern Bunger Hills was purely from the southern and eastern margins, although minor advances of the north-east flowing Edisto Glacier onto coastal areas occurred following retreat of the last extensive ice sheet phase.

Sub-surface pressure (SSP) data from tide gauges at three bases on the Pacific coast of the Antarctic Peninsula, together with SSP information from a bottom pressure recorder deployed on the south side of the Drake Passage, have been used to study the relationships between SSP, Drake Passage transport, and the strength of Southern Ocean zonal winds as represented by the Southern Annular Mode. High correlations were obtained between all parameters, confirming results obtained previously with independent data sets, and demonstrating the value of information from the permanent Rothera base, the southern-most site considered. These are important findings with regard to the design, installation and maintenance of observation networks in Antarctica. In particular, they provide the necessary justification for Antarctic Peninsula tide gauge infrastructure investment in the lead up to International Polar Year. Data delivery from Rothera and Vernadsky is currently being improved and should soon enable the first near real-time system for monitoring Drake Passage transport variability on intraseasonal timescales, an essential component of a Southern Ocean Observing System.

We provide the first comprehensive account of habitat preference, mating, oviposition and developmental stages of Parochlus steinenii. There are eight records from the South Shetland Islands. On King George Island, none out of 40 temporary ponds and 9% out of 44 lakes with variable water levels were inhabited by P. steinenii. By contrast, 94% of 52 lakes with stable water levels were occupied, for 92% of which breeding was confirmed. Lakes were occupied independently of their height above sea level ranging from 5 to 115 m. The midges aggregated at two different microhabitats at the shoreline of lakes. Terrestrial swarms of more than 5000 individuals at open wind sheltered rocks were strongly dominated by males. Their mean density was 40, their maximum 150 ind. cm−2. Aggregations under stones at the water edge showed a female-biased or equal sex ratio; their densities seasonally increased from 0.17 to 2.02 ind. cm−2. Female midges produced one to four egg batches totalling on average 247 eggs/female. Four larval stages can be clearly discriminated by head length. Our data on the habitat preferences and the high reproductive output predict that P. steinenii will rapidly colonize habitats that become available in the course of the regional warming of the Antarctic Peninsula region.

The age and conditions of metamorphism in the Highjump Archipelago, East Antarctica, are investigated using samples collected during the 1986 Australian Antarctic expedition to the Bunger Hills–Denman Glacier region. In situ U-Pb dating of monazite from three metasedimentary rocks yields ages between c. 1240–1150 Ma and a weighted mean 207Pb/206Pb age of 1183±8 Ma, consistent with previous constraints on the timing of metamorphism in this region and Stage 2 of the Albany–Fraser Orogeny in south-western Australia. This age is interpreted to date the development of garnet ± sillimanite ± rutile-bearing assemblages that formed at c. 850–950°C and 6–9 kbar. Peak granulite facies metamorphism was followed by decompression, evidenced largely by the partial replacement of garnet by cordierite. These new pressure–temperature determinations suggest that the Highjump Archipelago attained slightly higher temperature and pressure conditions than previously proposed and that the rocks probably experienced a clockwise pressure–temperature evolution.

The northern Victoria Land coastal marine environment was investigated during the late summer 2004, within the framework of the Latitudinal Gradient Project (LGP), to describe the physical, chemical and biological patterns of the water column and their relationship with the pelagic and benthic compartments, and to determine to what extent they change with latitude. A latitudinal gradient from Cape Adare to the Terra Nova Bay–Cape Russell area was determined on the basis of abiotic and trophic factors. Cape Adare had lower values of organic matter (particulate organic carbon < 150 μg l−1) available for the benthic communities, but this organic matter had good trophic quality. In Terra Nova Bay the particulate organic matter was quantitatively higher (organic carbon > 400 μg l−1), presumably reaching the bottom via faecal pellets, but was more detrital, although its nutritive value was still high (carbon protein content nearly 40%), as confirmed by the great quantity of phytopigments in the sediments (> 4.0 μg g−1). The benthic communities changed with latitude as well, partially reflecting the environmental and trophic gradient, but also showing a large within-area variability (except for the Cape Adare area), due to a complex array of variables that did not change with latitude.

The statolith microstructure was examined from seven species of seven families of Antarctic squid captured in Prydz Bay (n=23). Five of the species (Kondakovia longimana, Psychroteuthis glacialis, Brachioteuthis sp., Mastigoteuthis psychrophila, Galiteuthis glacialis) had very clear statolith growth increments which could be enumerated from the nucleus to the statolith margin. These increments were similar in appearance to daily statolith increments in other temperate and tropical squids. Psychroteuthis glacialis also had two distinct zones which may reflect growth during the pelagic and demersal phases of the life cycle. Total statolith increment counts were not possible on two of the species (Bathyteuthis abyssicola and Alluroteuthis antarcticus). The statolith microstructure of Bathyteuthis abyssicola had some very faint increments near the nucleus but increments were not visible in most of the statolith microstructure, while the statolith microstructure of A. antarcticus was indistinct in the nuclear region (possibly due to the formation of a second primordium during ontogenesis). Future research may reveal that statolith increments are useful tools for Antarctic squid age and growth studies.

From at least the Early Jurassic to the Miocene, eastward subduction of oceanic crust took place beneath the Antarctic Peninsula. Magmatism associated with the subduction generated a N-S linear belt of volcanic rocks known as the Antarctic Peninsula Volcanic Group (APVG), and which erosion has now exposed at about the plutonic/volcanic interface. Large central volcanoes from the APVG are described here for the first time. The structures are situated in north-west Palmer Land within the main Mesozoic magmatic arc. One centre, Zonda Towers, is recognized by the presence of a 160 m thick silicic ignimbrite, containing accidental lava blocks up to 25 m in diameter. This megabreccia is interpreted as a caldera-fill deposit which formed by land sliding of steep caldera walls during ignimbrite eruption and deposition. A larger centre, Mount Edgell-Wright Spires, is dominated by coarse-grained debris flow deposits and silicic ignimbrites which, with minor lavas and fine-grained tuffs, form a volcanic succession some 1.5 km thick. Basic intermediate and silicic sills c. 50 m thick intrude the succession. A central gabbro-granite intrusion is interpreted to be a high-level magma chamber of the Mount Edgell volcano.

Diatom assemblages from four different substrates from a stream on Byers Peninsula were analysed during the summer. The substrate type was the main factor explaining the variability in the diatom assemblages. Sandy biofilms showed a higher diversity and a greater number of endemic species. Two main hydrological regimes were observed: 1) a hydrologically unstable period with high variability in stream flow and successive freezing and thawing periods, 2) a late summer hydrologically stable period, characterized by low stream velocity and variability. The structure of the diatom communities was different between the two hydrological periods, although the substrate modulated the difference. The diatom assemblages showed low similarity among the substrates and high dominance of endemic species during early summer. The late summer community showed high dominance of motile cosmopolitan species on all substrate types. As the length of both hydrological regimes would ultimately be driven by climatic variability, the predicted climate warming could reduce overall stream diversity. Hence, subtle changes could alter the length of both hydrological periods. The relationship between diatom species association with different substrates and hydrological regimes could be relevant for tracking past climate variability using diatom palaeorecords.

Quantitative real time PCR is the most sensitive and widely used method for the analysis of gene expression. The choice of one or several reference genes is very important for a normalization process, which should not fluctuate under stress conditions, to reduce error rate and bias during experimental procedure. In the present study, the expression stability of nine reference genes (two actins, two tubulins, two elongation factor 1α, two ubiquitins, and cyclophilin) during abiotic stresses such as cold, salt, and PEG treatments, was evaluated on Deschampsia antarctica plants using geNorm software. Results from various experimental conditions indicated that cyclophilin and elongation factor 1α were the most stable genes in the leaf and the root, respectively. The expression of the other reference genes varied under stress. The relative quantification of the TACR7 gene varied according to the kind and the number of reference genes used, suggesting the importance of considering the implications of a combination of reference genes under different stress conditions and in different tissues.

The Antarctic Pearlwort, Colobanthus quitensis (Kunth.) Bartl. (Caryophyllaceae) is one of the two native vascular plant species that have successfully colonized the maritime Antarctic during the Holocene (Smith 1984). Within the Antarctic biome, it is only found on the Antarctic Peninsula and on islands in the maritime Antarctic (Smith 1984). Its distribution also includes South Georgia (sub-Antarctic), the Falkland Islands, and sites along the Andes, reaching c. 10°N in Mexico (Moore 1970). Moore (1970) observed that C. quitensis is self-compatible and appears to be largely, if not entirely, self-pollinated. Convey (1996), found that maritime Antarctic C. quitensis showed lower allocation to seed production than plants from sub-Antarctic sites.

Minette dykes intersect the Precambrian crystalline basement of Schirmacher Oasis, East Antarctica. The rocks have intermediate to basic compositions, showing shoshonitic to ultrapotassic character. The samples show enhanced concentrations of compatible elements and high mg# combined with extreme enrichments in LILE (especially Ba) and LREE. Mantle-normalized trace element patterns are characterized by coupled relative depletions of Nb and Ti and strong fractionations between LILE and HFSE. The minettes display fractionated chondrite-normalized REE patterns with high and varying LREE concentrations in contrast to relative low and nearly constant HREE contents. High magma-ascent and cooling rates of lamprophyric magmas argue against a fundamental change of the primary geochemical signatures in minette magmas by interactions with the continental crust during ascent. The major and trace element abundances of the studied minettes point to varying degrees of partial melting of a mantle source, which was enriched in LILE and LREE during or before the melting event. Incompatible element signatures argue for the involvement of subducted pelagic sediments.

Uptake and loss of water by six lichen species from the Argentine Islands, Antarctic Peninsula, were studied in their natural habitat and in laboratory studies. Under field conditions, during a period of rain, uptake of moisture ranged from 15% d w h−1 for Usnea antarctica to almost 90% for Mastodia tesselata. Loss rates after the rain ceased were lower than the uptake rates and ranged from 8.5% d w.h−1 in Umbilicaria decussata to 38.8% in M. tesselata. A comparison of thalli of M. tesselata from the shoreline with thalli collected further inland showed significant differences in maximum water content and in rates of water loss and uptake between thalli from these sites, which could be ascribed to the presence of salt in the thalli of M. tesselata from the shore. Thallus samples of Usnea antarctica collected from an exposed site showed lower uptake rates and higher loss rates of water than samples collected from a more sheltered site. Under laboratory conditions the maximum moisture content ranged from 67% in Usnea antarctica to 391% in M. tesselata. Exposed to an atmosphere of c. 40% relative humidity and c. 15°C, lichen thalli lost their water during the first hour of the experiment at rates ranging from 34% of the maximum moisture content in Umbilicaria propagulifera to 70% in U. decussata. Rates of water loss diminished with time, and after 4–6 hours equilibrium was reached, with water contents of 14–16% of thallus dry weight. The microclimate is the driving force for the thallus water regime. Specific differences in rates of water loss and water uptake depend on the morphology and anatomy of the lichen thalli. The results of the laboratory experiments agree with those from the field study. However, local differences in microclimatic or other environmental factors can be responsible for significant differences in the water regime of thalli of the same species, a result which can only be obtained from field studies.

Well-preserved vertebrate microremains are abundant in the residues from a calcareous grey siltstone in the karawaka biozone (?late Givetian) of the Aztec Siltstone at Mount Crean, Lashly Mountains, Antarctica. Acanthodians are represented by scales of acritolepid Pechoralepis juozasi sp. nov., climatiid Nostolepis sp. cf. N. gaujensis Valiukevičius, diplacanthid Milesacanthus antarctica Young & Burrow, and an undetermined acanthodiform. The acanthodian assemblage resembles those from early Frasnian carbonates of central Iran. Chondrichthyan elements in the fauna include rare teeth of Aztecodus harmsenae Long & Young and Antarctilamna prisca Young, ctenacanthoid-type scales and branchial denticles which are possibly from Antarctilamna, and scales of an indeterminate chondrichthyan. An isolated set of acanthodid acanthodiform jaws from the uppermost ‘phyllolepid’ biozone of the Aztec Siltstone at Mount Ritchie, Warren Range, Antarctica is also described.

Roots of nine of the 12 vascular plant species present on sub-Antarctic Heard Island were examined for mycorrhizae. All species examined had some type of mycorrhization with most possessing associations with vesicular-arbuscular mycorrhizae or dark septate mycorrhizae. The degree of mycorrhization varied considerably across sites. Sampled plants were growing on either morainic or beach substrates with some areas exposed only in the last century. As mycorrhizae are known to play an important role in the nutrient uptake by host-plants, these results support the idea that mycorrhizae can influence the capacities of plants to colonize in cold and low-nutrient environments such as sub-Antarctic glacier forelands. Comparisons with data from other sub-Antarctic islands are made.

Lac d'Armor (49°27′S, 69°42′E) is a medium-sized, fjord-type lake located on the ‘Grande Terre’ island of the Kerguelen archipelago. A dense grid of high-resolution reflection seismic profiles was collected from this lake basin. The seismic stratigraphic facies reveal a last deglaciation to Holocene infill comparable to the seismic facies found in other glacigenic lakes all over the world. Remarkable features in the seismic stratigraphy are mounded structures found at the southern edge of both sub-basins. The sediment mounds can be interpreted as sediment drifts created by wind-induced bottom currents. The onset of the build-up of these drifts initiated at some point in the Holocene and indicates a strengthening of the southern Westerlies, which are currently the dominant winds on this island.