We present geochronological and geochemical data for eight plutonic rocks from five locations in the Pine Island Bay area of West Antarctica, collected during RV Polarstern expedition ANT-XXIII/4. Ar-Ar laser method dating yielded closure temperatures ages of c. 147–98 Ma for dioritic and granitic plutonic rocks and an age range of c. 97–95 Ma for granitoid and trachyandesitic dykes. Major and trace element compositions indicate that all rocks have an I-type subduction-related chemistry. There are no A-type granitic rocks in our dataset, and none are yet reported from the Pine Island Bay area. Our results confirm earlier models of post 100 Ma subduction on this part of the Gondwana margin.

Changes of glaciers and snow cover in polar regions affect a wide range of physical and ecosystem processes on land and in the adjacent marine environment. In this study, we investigated the potential of 11-day repeat high-resolution satellite image time series from the TerraSAR-X mission to derive glaciological and hydrological parameters on King George Island, Antarctica, between 25 October 2010 and 19 April 2011. The spatial pattern and temporal evolution of snow cover extent on ice-free areas can be monitored using multi-temporal coherence images. Synthetic aperture radar (SAR) coherence is used to map glacier extent of land-terminating glaciers with an average accuracy of 25 m. Multi-temporal SAR colour composites identify the position of the late summer snow line at ~220 m a.s.l. Glacier surface velocities are obtained from intensity feature-tracking. Surface velocities near the calving front of Fourcade Glacier were up to 1.8±0.01 m d-1. Using an intercept theorem based on fundamental geometric principles together with differential GPS field measurements, the ice discharge of Fourcade Glacier was estimated at 20 700±5500 m3 d-1 (corresponding to ~19±5 kt d-1). The rapidly changing surface conditions on King George Island and the lack of high-resolution digital elevation models for the region remain restrictions for the applicability of SAR data and the precision of derived products. Supplemental data are available at http://dx.doi.org/10.1594/PANGAEA.853954.

The mental barbel, an important diagnostic character among notothenioid fishes of the family Artedidraconidae, is highly variable in Pogonophryne scotti. A collection of 92 specimens of this species from the South Orkney Islands, comprising both sexes and a wide range of sizes, was studied to determine intraspecific variation in barbel size, shape and ornamentation (development of papillae and folds, especially on the tip). Four distinct barbel types, based on external morphology, are represented in this material: scotti (4.3%), phyllopogon (28.3%), dolichobranchiata (4.3%) and brainlike (38.1%). Indeterminate barbels (25.0%), observed in specimens of both sexes and all sizes, exhibit varying degrees of ornamentation and suggest that all barbel types represent the range of variability in P. scotti. There is no correlation between sex and barbel type. Barbels exhibit negative allometric growth relative to body size. Specimens of at least 119 mm SL generally exhibit greater development of the terminal expansion, resulting in a convoluted brainlike appearance previously unrecorded for P. scotti. Indeterminate and phyllopogon barbels are most common among specimens of 119–210 mm SL. All barbel types are similar histologically. A core of pseudocartilage is surrounded by connective tissue, and the entire barbel is well supplied with blood vessels and nerves. Papillae and folds are dermal projections covered by epidermis. The variation exhibited by the barbel of P. scotti. formerly served as the basis for distinguishing this species from the invalid species P. phyllopogon and P. dolichobranchiata. Such intraspecific variation is atypical for Pogonophryne but underscores the need to fully validate any taxonomic character.

Allan Hills nunatak, south Victoria Land, Antarctica, exposes an exceptional example of a shallow depth (< 500 m) intrusive complex formed during the evolution of the Ferrar large igneous province (LIP). Dyke distribution, geometries and relationships allow reconstruction of its history and mechanics of intrusion. Sills interconnect across host sedimentary layers, and a swarm of parallel inclined dolerite sheets is intersected by a radiating dyke-array associated with remnants of a phreatomagmatic vent, where the dolerite is locally quenched and mixed to form peperite. Intrusion geometries, and lack of dominant rift-related structures in the country rock indicate that magma overpressure, local stresses between mutually interacting dykes and vertical variations of host rock mechanical properties controlled the intrusive process throughout the thick and otherwise undeformed pile of sedimentary rocks (Victoria Group). Dolerite sills connected to one another by inclined sheets are inferred to record the preferred mode of propagation for magma-carrying cracks that represent the shallow portions of the Ferrar LIP plumbing system.

Mount Willing in the Prince Charles Mountains (East Antarctica) is part of the Fisher Volcano–plutonic complex which formed as part of the global-scale Grenvillian mobile belt system. Mount Willing is composed of four rock complexes: 1) a metamorphic sequence, 2) gabbro intrusions, 3) deformed felsic intrusives, and 4) abundant post-metamorphic dykes and veins. Three rock types constitute the metamorphic sequence: amphibole–biotite felsic plagiogneiss, mafic to intermediate biotite–amphibole schist, and biotite paragneiss. The bulk composition of the mafic schists classifies them as tholeiitic basalts, and rarely as basaltic andesites or andesites. Index mg ranges widely from 47 to 71. Concentrations of TiO2, P2O5, and high-field strength elements are high in some rocks. These rocks are thought to have been derived from enriched (subcontinental) mantle sources. Sm–Nd and U–Pb isotopic data indicate a series of Mesoproterozoic thermal events between 1100 and 1300 Ma. In particular, these events occurred at 1289 ± 10 Ma (volcanic activity), at 1177 ± 16 Ma (tonalite intrusion), at 1112.7 ± 2.4 and at 1009 ± 54 Ma (amphibolite facies metamorphic events). Rb–Sr systematics also indicates a thermal overprint at 636 ± 13 Ma. Mafic schists show low initial 877Sr/86Sr ratios between 0.7024 and 0.7030. Felsic rocks show higher Sri values between 0.7037 and 0.7061. Basaltic andesite metavolcanic and plutonic rocks form a calc-alkaline evolutionary trend, and probably originated from subduction-modified mantle sources in a convergent plate margin environment. An oceanic basin may have existed in central Prince Charles Mountains about 1300 Ma ago and was closed as a result of continental collision around 1000 to 800 Ma.

Surface mineralogical compositions and their association to modern processes are well known from the east Atlantic and south-west Indian sectors of the Southern Ocean, but data from the interface of these areas - the Prydz Bay–Kerguelen region - is still missing. The objective of our study was to provide mineralogical data of reference samples from this region and to relate these mineralogical assemblages to hinterland geology, weathering, transport and depositional processes. Clay mineral assemblages were analysed by means of X-ray diffraction technique. Heavy mineral assemblages were determined by counting of gravity-separated grains under a polarizing microscope. Results show that by use of clay mineral assemblages four mineralogical provinces can be subdivided: i) continental shelf, ii) continental slope, iii) deep sea, iv) Kerguelen Plateau. Heavy mineral assemblages in the fine sand fraction are relatively uniform except for samples taken from the East Antarctic shelf. Our findings show that mineralogical studies on sediment cores from the study area have the potential to provide insights into past shifts in ice-supported transport and activity and provenance of different water masses (e.g. Antarctic slope current and deep western boundary current) in the Prydz Bay–Kerguelen region.

In this paper we report the first characterization of cultivable bacteria obtained from the Antarctic sea urchin Sterechinus neumayeri. The coelomic fluid was obtained from a pool of sea urchins which was plated onto different media to isolate the bacteria. A total of 42 isolates of psychrotrophic and aerobic γ-Proteobacteria (59.5%), Flavobacteria (33.3%) and Actinomycetes (7.2%) were isolated and sequenced. These bacteria were exposed to heavy metals and antibiotics, where 38 strains were analysed by the minimal inhibitory concentration method. Antibiotic resistance was detected in 44% of cultivable strains, and a further 13% presented co-resistance to antibiotics and heavy metals. The genera of bacteria that showed an increased resistance and co-resistance to metals and antibiotics were Flavobacterium, Psychrobacter and Pseudomonas. Additionally, 30.9% of isolated bacterial strains contained plasmids, which are probably related to resistance and co-resistance to metals. These results indicate that sea urchin-associated bacteria could be reservoirs for antibiotic resistance genes.

Specimens of Prasiola collected from habitats not experiencing nutrient enrichment from birds are considered to be P. calophylla. The alga has three distinct growth forms; uniseriate filaments, narrow ribbons and expanded sheets. Reproduction is by aplanospores and fragmentation of the thallus. The known Antarctic distribution is disjunct with only two records outside Victoria Land. However, it is widespread in the latter region. The alga is absent from areas where there are high salt concentrations in waters and soils. Elsewhere it is common in streams and on water-flushed ground as well as occurring on terminal ice-faces of glaciers and as chasmoendolithic growths. Ribbons are found mostly on the lower surfaces of stones, and uniseriate filaments on the exposed surfaces of the stream beds of seasonal melt streams. Expanded sheets occur in less vigorous water flows. There is a need for further culture and field studies in order to understand the factors which control morphological development and distribution patterns.

Two surveys were carried out in the Ross Sea region during February and March 2004 and 2008 from the New Zealand RV Tangaroa. Fishes were sampled on the continental shelf and slope of the Ross Sea, and on adjacent seamounts to the north, mainly using a large demersal fish trawl and a large mesopelagic fish trawl. Parts of the shelf and slope were stratified by depth and at least three random demersal trawls were completed in each stratum, enabling biomass estimates of demersal fish to be calculated. Fish distribution data from these two surveys were supplemented by collections made by observers from the toothfish fishery. A diverse collection of over 2500 fish specimens was obtained from the two surveys representing 110 species in 21 families. When combined with previous documented material this gave a total species list of 175, of which 135 were from the Ross Sea shelf and slope (to the 2000 m isobath). Demersal species-richness, diversity and evenness indices all decreased going from the shelf to the slope and the seamounts. In contrast, indices for pelagic species were similar for the slope and seamounts/abyss but were much lower for the shelf.

Currently, a substantial proportion of Antarctic research is carried out through deployment of field camps, but little detailed information on the running of these facilities is often available. The remoteness of camps and the fragility of local Antarctic terrestrial ecosystems make the running of sustainable, low impact field science and logistics in ice-free areas a challenge for environmental managers. In this study we examined the environmental management at the Spanish camp within Antarctic Specially Protected Area (ASPA) No. 126 Byers Peninsula, Livingston Island, South Shetland Islands. Firstly, the input of materials and generation of pollution associated with the camp during a ten year period of operation was quantified. Examination of greenhouse gas emissions shows a mean of 14 t CO2 equivalent per researcher associated with transportation of people to the site, plus 44 t CO2 equivalent per researcher, associated with transportation of cargo to the field site. Secondly, the cumulative trampling footprint across Byers Peninsula and associated local impacts were recorded. Results showed the pattern of human movement within the ASPA and how activities concentrated around the field camp site. At the same time every effort was taken to ensure scientific outputs from research activities within the ASPA were maximized. Practical recommendations on operational logistics are discussed to minimize environmental impacts and optimize scientific benefits.

Satellite transmitters were attached to eight adult spectacled petrels Procellaria conspicillata Gould captured during the early incubation period at their breeding grounds on Inaccessible Island, one of the Tristan da Cunha Islands in the central South Atlantic Ocean. Data on their at-sea distribution was obtained for up to six months. All birds remained within the South Atlantic from 24–44°S, with most between 25 and 40°S. Breeding birds mainly foraged in oceanic waters, but failed breeders or non-breeders concentrated their foraging activity over the Rio Grande Rise and the Walvis Ridge and along the shelf break off the east coast of South America. Little foraging occurred along the Benguela shelf break off southern Africa. Non-breeders favoured relatively warm water with low chlorophyll concentrations, reducing the risk of bycatch in fisheries. Tracked birds spent 16% of their time in areas with high levels of tuna longline fishing activity, with overlap greater for non-breeding birds (22%) than breeding birds (3%). Birds in this study foraged in shallower waters along the continental shelf edge off South America than spectacled petrels tracked in this area in winter, potentially increasing their risk of exposure to demersal longline fisheries in this area in summer.

Measurement of light intensity transmission was carried out on an ice core S100 from coastal Dronning Maud Land (DML). Ice lenses were observed in digital pictures of the core and recorded as peaks in the light transmittance record. The frequency of ice layer occurrence was compared with climate proxy data (e.g. oxygen isotopes), annual accumulation rate derived from the same ice core, and available meteorological data from coastal stations in DML. The mean annual frequency of melting events remains constant for the last ∼150 years. However, fewer melting features are visible at depths corresponding to approximately 1890–1930 AD and the number of ice lenses increases again after 1930 AD. Most years during this period have negative summer temperature anomalies and positive annual accumulation anomalies. The increase in melting frequency around ∼1930 AD corresponds to the beginning of a decreasing trend in accumulation and an increasing trend in oxygen isotope record. On annual time scales, a relatively good match exists between ice layer frequencies and mean summer temperatures recorded at nearby meteorological stations (Novolazarevskaya, Sanae, Syowa and Halley) only for some years. There is a poor agreement between melt feature frequencies and oxygen isotope records on longer time scales. Melt layer frequency proved difficult to explain with standard climate data and ice core derived proxies. These results suggest a local character for the melt events and a strong influence of surface topography.

Aeromagnetic data collected on the GANOVEX IV and GANOVEX VI expeditions are combined in this report to give a synoptic view of the western Ross Sea, Antarctica. The addition of the new GANOVEX VI data allows the identification of the southern boundary of the “Ross Sea Unit” — a magnetic unit containing rift-fabric anomalies of the West Antarctic rift system in the Victoria Land basin. Although this boundary has a similar WSW–ENE orientation to the northern boundary, as identified in the GANOVEX IV survey, the newly identified southern magnetic unit (called the “Ross Island and Ice Shelf Edge Unit”) includes evidence of the S–N rift-fabric that is not found in the north, i.e. the rift-fabric continues farther south. The linear boundaries themselves are interpreted as transfer faults as proposed by previous workers for the tectonic development of the Ross Sea area.

Trematomus newnesi inhabited inshore (<20 m) subzero waters in McMurdo Sound where it fed in the water column on Euphausia crystallorophias and fishes. This sample included the largest reported specimens of this species. The length–weight relationship was Weight = 3.17 × 10−6 (Standard Length)3.34, n = 67, r2 = 0.95. The population was phenotypically plastic, with two distinct morphs easily separated by visual inspection – the typical morph and a large mouth/broad headed morph comprising 28% of the sample. The large mouth morph had a wider and blunter head, longer upper jaw, wider gape, more heavily ossified jaws and darker colouration. To document this morphology, four views of the head are illustrated. Inference from morphology and measurements suggested that the large mouth morph was more benthic than the typical semipelagic morph. Museum specimens from Cape Adare confirmed the presence of the large mouth morph 700 km north of McMurdo Sound. This is the first clear example of phenotypic plasticity in any species of marine fish and its discovery extends the bounds of the nototheniid adaptive radiation to the population level. This finding suggests ecological and evolutionary parallels between the inshore waters of the high Antarctic shelf and the low diversity ichthyofaunas of Arctic, boreal and some temperate lakes. Although there is no data on genetic diversification, an alternate interpretation of the phenotypic plasticity is that the large mouth morph is a cryptic or sibling species.

Byers Peninsula, Livingston Island, was one of the first sites in Antarctica designated for environmental conservation and scientific protection. Research on Byers Peninsula has been predominantly international, with 88 indexed publications (93% of them published during last 20 years) from 209 authors affiliated to 110 institutions from 22 nations, all of which are signatories to the Antarctic Treaty. Palaeontological research represented 20% of the published articles. The variety of freshwater bodies within the area has made Byers Peninsula a reference site for limnological studies (24% of papers). The site also contains numerous outcrops and periglacial features relevant to geology, stratigraphy and geomorphology (29%). Terrestrial biodiversity is extraordinarily high for lichens, bryophytes and invertebrates (15% of articles). Only 5% of the publications concern research on human activities, including both archaeology and impact monitoring. Glaciology, meteorology and climatology studies represent only 7% of papers. This work highlights the international and multidisciplinary nature of science conducted on Byers Peninsula in order to promote international cooperation and to provide information relevant for environmental management and conservation.

This paper reports on the remapping of a carefully documented vegetation plot at Cape Hallett (72°19′S 170°16′E) to provide an assessment of the rates of vegetation change over decadal time scales. E.D. Rudolph, in 1962, mapped in detail the vegetation of a site approximately 28 m by 120 m at Cape Hallett, Victoria Land, Antarctica. This site was relocated and remapped in January 2004 and changes were assessed using GIS techniques. This appears to be the longest available time period for assessing vegetation change in Antarctica. The analysis indicated that considerable change had occurred in moss and algae distribution patterns and this seems to have been caused by increased water supply, particularly in wetter areas. There was also evidence of some change in lichen distribution. The extent of the change indicates that vegetation cover can be used for monitoring change in areas as extreme as the Ross Sea region. For this analysis to be successful it was important that the mapping techniques used were totally explicit and could easily be replicated. Fortunately, Rudolph had defined his cover classes and the site was also clearly marked. The application of GIS mapping techniques allows the mapping to be more explicitly defined and easily replicated.

This study concerned the fragility of maritime Antarctic soils under increasing temperature, using the C dynamics and structural characteristics of humic substances as indicators. Working with four representative soils from King George Island (Lithic Thiomorphic Cryosol (LTC1 and LTC2), Ornithogenic Cryosol (OG) and Gelic Organosol (ORG)) we evaluated the total organic C and nitrogen contents, the oxidizable C and humic substances. Soil samples were incubated to assess the amount of C potentially mineralizable at temperatures typical of an Antarctic summer (5–14°C). Humic acids showed a higher aliphatic character and a smaller number of condensed aromatic groups, which suggests that these molecules from Antarctic soils are generally less resistant to microbial degradation than humic acids molecules from other regions. Based on 13C NMR spectra of MAS and CP/MAS, samples of soil humic acids of mineral soils (LTC1 and LTC2) have a higher content of aliphatic C, and heteroatom C, with lower levels of carbonyl and aromatic C, when compared with organic matter-rich soils (OG and ORG). Increasing incubation temperature led to a higher rate of mineralizable C in all soils. A sequence of soil fragility was suggested - LTC1 and LTC2 > OG > ORG - which showed a correlation with the Q10 coefficient and the ratio of labile and recalcitrant C fractions of soil organic matter (R2 = 0.83).

High resolution firn core records of the oxygen isotope ratio (δ18O) and trace chemical species were extracted from a high accumulation site on Law Dome, East Antarctica. Inter-core comparisons were conducted and regional events identified in cores 5 km apart. High resolution dating of one of the firn cores was established using a co-located Automatic Weather Station (AWS) equipped with a snow accumulation sensor, allowing dating of individual precipitation events in the firn core record. Variations in the δ18O and trace chemical records were compared with meteorological conditions at the mesoscale and the synoptic-scale. Particular focus was given to an abrupt change in sea salt concentrations and δ18O within a depth range that appears from AWS accumulation data to have been deposited over a 24 hour period. The abrupt change in the firn core record was found to be consistent with an abrupt change in meteorological conditions. Direct comparisons between high resolution firn core records and meteorological conditions will greatly facilitate the interpretation of signals preserved in deep ice cores.

Meltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to > 80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3–5 to > 60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0–15% of the volume of each pond was still liquid, although this represented 5–35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period.