Byrd Glacier has one of the largest ice catchment areas in Antarctica, delivers more ice to the Ross Ice Shelf than any other ice stream, and is the fastest of these ice streams. A force balance, combined with a mass balance, demonstrates that stream flow in Byrd Glacier is transitional from sheet flow in East Antarctica to shelf flow in the Ross Ice Shelf. The longitudinal pulling stress, calculated along an ice flowband from the force balance, is linked to variations of ice thickness, to the ratio of the basal water pressure to the ice overburden pressure where Byrd Glacier is grounded, and is reduced by an ice-shelf buttressing stress where Byrd Glacier is floating. Longitudinal tension peaks at pressure-ratio maxima in grounded ice and close to minima in the ratio of the pulling stress to the buttressing stress in floating ice. The longitudinal spacing of these tension peaks is rather uniform and, for grounded ice, the peaks occur at maxima in surface slope that have no clear relation to the bed slope. This implies that the maxima in surface slope constitute a “wave train” that is related to regular variations in ice-bed coupling, not primarily to bed topography. It is unclear whether these surface “waves” are “standing waves” or are migrating either upslope or downslope, possibly causing the grounding line to either retreat or advance. Deciding which is the case will require obtaining bed topography in the map plane, a new map of surface topography, and more sophisticated modeling that includes ice flow linked to subglacial hydrology in the map plane.

Antarctic toothfish Dissostichus mawsoni and Weddell seals Leptonychotes weddellii are important mesopredators in the waters of the Antarctic continental shelf. They compete with each other for prey, yet the seals also prey upon toothfish. Such intraguild predation means that prevalence and respective demographic rates may be negatively correlated, but quantification is lacking. Following a review of their natural histories, we initiate an approach to address this deficiency by analysing scientific fishing catch per unit effort (CPUE; 1975–2011 plus sporadic effort to 2018) in conjunction with an annual index of seal abundance in McMurdo Sound, Ross Sea. We correlated annual variation in scientific CPUE to seal numbers over a 43 year period (1975–2018), complementing an earlier study in the same locality showing CPUE to be negatively correlated with spatial proximity to abundant seals. The observed relationship (more seals with lower CPUE, while controlling for annual trends in each) indicates the importance of toothfish as a dietary item to Weddell seals and highlights the probable importance of intra- and inter-specific competition as well as intraguild predation in seal-toothfish dynamics. Ultimately, it may be necessary to supplement fishery management with targeted ecosystem monitoring to prevent the fishery from having adverse effects on dependent species.

The identification and quantification of Antarctic Pygoscelis penguin colonies depends increasingly on recognition of the characteristic optical properties of guano deposits, but almost all knowledge of these properties until now has been compromised by resolution and atmospheric propagation effects. Here we present hyperspectral reflectance data in the range 350–2500 nm, collected in situ from fresh guano deposits in Pygoscelis penguin colonies on Signy Island, South Orkney Islands. The period of data collection included the transition from predominantly white guano to the pink coloration characteristic of a krill-rich diet. The main identifiable features in the spectra are a broad absorption feature centred around 550 nm, responsible for the pink coloration and identified with the pigment astaxanthin, as well as several water absorption features. Variations in these features are responsible for differentiation between spectra. From these results we propose two spectral indices suitable for use with satellite data, one of which responds to the presence of astaxanthin in the guano and the other to water. Our results do not allow us to differentiate between penguin species from their guano, but do suggest that the breeding phenology of Pygoscelis penguins could be determined from a time series of multispectral imagery.

Lithium distributions in lake and pond waters of the McMurdo Dry Valleys of southern Victoria Land, Antarctica were studied to elucidate the origin of dissolved salts and the evolutionary history of the lakes and ponds. The EfLi [(Li/Cl)sample/(Li/Cl)seawater] values of the bottom waters in Lakes Bonney and Fryxell were higher than unity (EfLi=4–7), indicating that the salts originated from sea salts (probably relict seawater) and have been subsequently modified by the contribution of meltwaters containing atmospheric fallout and/or rock and soil weathering products. In contrast, extremely high Li concentrations with high EfLi values in the Don Juan Pond water (EfLi = 180) and the bottom waters of Lake Vanda (EfLi = 40) suggest that the salts originated from deep groundwaters influenced mainly by saline water-rock interactions, as supported by the dissolution experiments of granite in NaCl solution. The low Li concentrations of pond waters with high EfLi values in the Labyrinth indicate that the salts are derived from atmospheric fallout. The decrease of the EfLi values with the increase of Cl concentrations can be explained by the repeated cycles of the migration of Li into the ice phase and subsequent ablation of surface ice, as indicated by seawater freezing experiments.

The petrography and mineralogy of Iherzolite nodules from an intrusive body of alkaline-ultrabasic rocks on Jetty Peninsula. The nodules are massive with a porphyritic hypidiomorphic granular texture. The main rock-forming minerals are: olivine, pyroxene, garnet and chrome spinel. The nodules are coarse granular spinel-garnet Iherzolites that are chemically similar to pyrope peridotite from Krezemze, Czechoslovakia, and pyrope-bearing peridotite from alkaline ultrabasites of Yakutia, USSR. The Al2O3 content in enstaties and Ca/(Ca + Mg) ratio in co-existing chrome diopside suggest that equilibrium conditions of the mantle mineral assemblage are: T = 875–900°C, P = 20–24 kbar, conditions typical of the spinel-pyrope facies of the upper mantle. Depths of withdrawal of the inclusions do not exceed 60–75 km. Available age determinations of the intrusive alkaline-ultrabasic rocks (145–150 Ma) suggest that alkaline-ultrabasic magmatism and withdrawal of plutonic nodules were related to rifting which resulted in the breakup of the Gondwana supercontinent in the late Mesozoic.

We analysed histological characteristics of gonads and reproductive effort of the small deep-living dragonfishes Akarotaxis nudiceps (Waite) and Bathydraco marri Norman collected in the south-western Ross Sea. From a macroscopic point of view, most specimens of B. marri were juveniles in early stages of gonad maturity, except for a maturing female. Conversely, the sample of A. nudiceps was composed of both immature and adult fish in different stages of maturity. A single A. nudiceps female was mature with a gonadosomatic index of 9.8%. Its absolute and relative fecundity was 260 oocytes and 31.5 oocytes g−1 TW, respectively, with a mean size of ripe oocytes of 1.9 mm. Gametogenesis in both species closely resembled that observed in other notothenioids, with females possessing two well-defined groups of oocytes. One group consisted of previtellogenic oocytes as a reserve stock while the other group was maturing oocytes to be ovulated in the current spawning season. A distinctive feature of oogenesis in recovering and maturing females of A. nudiceps was the presence of both postovulatory follicles in different stages of reabsorption and atretic oocytes. Based on low absolute fecundity, it is possible that A. nudiceps provides parental care and egg guarding.

We identified two ice-binding protein (IBP) sequences, named EFsymbAFP and EFsymbIBP, from a putative bacterial symbiont of the Antarctic psychrophilic ciliate Euplotes focardii. EFsymbAFP is 57.43% identical to the antifreeze protein (AFP) from the Stigmatella aurantiaca strain DW4/3-1, which was isolated from the Victoria Valley lower glacier. EFsymbIBP is 53.38% identical to the IBP from the Flavobacteriaceae bacterium strain 3519-10, isolated from the glacial ice of Lake Vostok. EFsymbAFP and EFsymbIBP are 31.73% identical at the amino acid level and are organized in tandem on the bacterial chromosome. The relatively low sequence identity and the tandem organization, which appears unique to this symbiont, suggest an occurrence of horizontal gene transfer (HGT). Structurally, EFsymbAFP and EFsymbIBP are similar to the AFPs from the snow mould fungus Typhula ishikariensis and from the Arctic yeast Leucosporidium sp. AY30. A phylogenetic analysis showed that EFsymbAFP and EFsymbIBP cluster principally with the IBP sequences from other Antarctic bacteria, supporting the view that these sequences belong to an Antarctic symbiontic bacterium of E. focardii. These results confirm that IBPs have a complex evolutionary history, which includes HGT events, most probably due to the demands of the environment and the need for rapid adaptation.

Retention of mineral elements in precipitation by mosses and lichens involving ion exchange and chelation mechanisms is a source of nutrients for these biota growing on rocks and nutrient poor soils (Brown 1987, Crittenden 1989). In qualitative work not involving nitrogen (N) Allen et al. (1967) demonstrated that fresh Antarctic mosses treated with hydrochloric acid could retain Na, P, Ca and K after leaching with concentrated solution of these elements. Ahumic fellfield soils are widespread in Antarctica and support sparse plant growth. This short note reports the results of work designed to show that fellfield soils and plants may obtain most of their N from atmospheric precipitation.

The McMurdo Dry Valleys of Antarctica are a climate-sensitive ecosystem, where future projected climate warming will increase liquid water availability to release soil biology from physical limitations and alter ecosystem processes. For example, many studies have shown that CO2 flux, an important aspect of the carbon cycle, is controlled by temperature and moisture, which often overwhelm biotic contributions in desert ecosystems. However, these studies used either single-point measurements during peak times of biological activity or diel cycles at individual locations. Here, we present diel cycles of CO2 flux from a range of soil moisture conditions and a variety of locations and habitats to determine how diel cycles of CO2 flux vary across gradients of wet-to-dry soil and whether the water source influences the diel cycle of moist soil. Soil temperature, water content and microbial biomass significantly influenced CO2 flux. Soil temperature explained most of the variation. Soil CO2 flux moderately increased with microbial biomass, demonstrating a sometimes small but significant role of biological fluxes. Our results show that over gradients of soil moisture, both geochemical and biological fluxes contribute to soil CO2 flux, and physical factors must be considered when estimating biological CO2 flux in systems with low microbial biomass.

This paper presents the first fossil penguin from East Antarctica, and the only one known south of the Antarctic Circle. It is represented by two well-preserved elements of the wing skeleton, humerus and radius, obviously assignable to the extant genus Spheniscus. They were found in the glaciomarine succession of the Fisher Bench Formation (Fisher Massif, Prince Charles Mountains, Mac. Robertson Land), which was dated using Strontium Isotope Stratigraphy to be Late Miocene in age (10.2 Ma). They are only slightly younger than the oldest remains undoubtedly attributable to this taxon. The X-ray diffraction and Fourier Transform Infrared Spectroscopy indicate diagenetic alteration of the original bone bioapatite under dominantly marine conditions. The Late Miocene was a period of ice margin retreat and marine incursion into the Lambert embayment that followed Middle Miocene cooling of the Antarctic climate. The fossils strongly suggest that variable climatic and environmental conditions in East Antarctica may have been an important factor in the evolution of penguins there during the Neogene.

A new fossil teleost, belonging to the family Aspidorhynchidae Nicholson & Lydekker, Aspidorhynchus antarcticus sp. nov., was obtained from a block of reworked Upper Jurassic tuffaceous mudstone in the lower (Albian) part of the mid-Cretaceous Whisky Bay Formation of James Ross Island, Antarctic Peninsula. Additional material, assignable to Aspidorhynchus sp., was collected from in situ Upper Jurassic marine rocks (Nordenskjöld Formation) at Longing Gap, northern Antarctic Peninsula. Not only is this the first reported occurrence of the family from Antarctica, it is also the first unequivocal record of Aspidorhynchus outside Europe; prior to this discovery, the genus had only been reported with certainty in marine deposits from the Middle Jurassic to Lower Cretaceous of England, France and Germany. This is the earliest neopterygian fish so far recovered from marine rocks in the Antarctic.

A new fossil agnathan, Turinia antarctica sp. nov., based on numerous isolated scales, comes from the lower fish-bearing beds of the Aztec Siltstone. Scales from moraine at Mount Suess, originally described as selachian or psammosteid heterostracan, are referred to the new species which shows close affinity with T. gondwana from Bolivia and T. cf. hutkensis from Iran. Reassessment of the biostratigraphy of Middle Devonian turiniid scales suggests that the lower part of the Aztec Siltstone may be of Eifelian age.

The female attendance behaviour of Antarctic fur seals (Arctocephalus gazella) and subantarctic fur seals (A.tropicalis), which breed sympatrically on subantarctic Marion Island, was investigated. Over the same period after the breeding season, the mean duration of feeding trips to sea, and percentage of time spent at sea, did not differ significantly between lactating females of the two species. The difference in mean duration of shore visits was significant and the longer onshore attendance of A. tropicalis probably related to the lower demand by their pups which grow at a slower rate. The subpolar maternal adaptations of A. gazella were unchanged under the more temperate environment at Marion Island, and it remains to be established unequivocally whether conditions there are limiting to the species.

Introduced house mice Mus musculus L. have been discovered to be major predators of chicks of the Tristan albatross Diomedea dabbenena L. and Atlantic petrel Pterodroma incerta Schlegel and to also predate great shearwater Puffinus gravis O'Reilly chicks at Gough Island, and similar predatory behaviour has been reported for house mice on Marion Island. Observations on Gough Island over three breeding seasons of nesting Atlantic yellow-nosed albatrosses Thalassarche chlororhynchos Gmelin and dark-mantled sooty albatross Phoebetria fusca Hilsenberg indicate that house mice are also preying on these two species: the first records of mice preying upon summer-breeding albatross species on Gough Island. Predation on these two albatross species appears to be relatively rare (∼2% for the Atlantic yellow-nosed albatrosses) and ongoing monitoring is required to ascertain if the impact of mice is increasing. Conservation actions to eradicate mice from Gough Island will be of benefit to these species and other species that are being impacted by this invasive species.

Snow samples taken at various distances from the emperor penguin (Aptenodytes forsteri) colony near Halley station were analysed by ion chromatography. Extremely high ammonium concentrations were encountered at the colony itself, but fell off sharply with distance from the colony, reaching background levels within a few kilometres of the colony. A seasonal effect was also seen, with the highest concentrations found in spring when the colony was at its most active. Levels of potassium and other sea-salt ions were also elevated near the colony. The ratio of sodium to potassium was lower than that found in bulk seawater, and closer to that found in the penguin's food source, indicating that the increased concentrations are due to emissions from the penguins and not merely to the proximity of open seawater to the site. The colony thus has a significant effect on the composition of the nearby snow, but this effect is strongly localised and is not likely to significantly influence snow chemistry at inland ice core drilling sites.

Recently, the Antarctic Peninsula has received more attention due to the pronounced warming in that region. Non-glaciated coastal areas on the Peninsula can be significant energy sources for the atmosphere when they are exposed during summer despite the high degree of cloud associated with the frequent passage of low pressure systems. An eddy covariance system was established in December 2002 to evaluate the turbulent energy exchanges between the atmosphere and a non-glaciated coastal area on King George Island. Monthly average downward shortwave radiation was less than 210 Wm-2 in summer. Due to the low albedo of 0.12, monthly average net radiation reached > 130 Wm-2, a magnitude that was significantly larger than the reported magnitudes of < ~70 Wm-2 at glaciated areas with a high albedo on the Peninsula. The sum of monthly average sensible heat (< 64 Wm-2) and latent heat (< 20 Wm-2) fluxes amounted up to ~80 Wm-2, which was an order of magnitude larger than those at glaciated areas on the Antarctic Peninsula. Given that non-glaciated areas should be enlarged if the warming continues, more attention may need to be paid to the role of non-glaciated areas in the local climate to predict climate change on the Antarctic Peninsula.

We describe a new chimaeriform fish, Callorhinchus torresi sp. nov., from the uppermost Cretaceous (late Maastrichtian) of the López de Bertodano Formation, Isla Marambio (Seymour Island), Antarctica. The material shows it is distinct from currently known fossil and extant species of the genus, whereas the outline of the tritors (abrasive surfaces of each dental plate) shows an intermediate morphology between earlier records from the Cenomanian of New Zealand and those from the Eocene of Isla Marambio. This suggests an evolutionary trend in tritor morphology in the lineage leading to modern callorhynchids, during the Late Cretaceous-Palaeogene interval.

Palaeopalynological studies form an integral part of the geological investigation of the Late Paleozoic sedimentary history of Dronning Maud Land. During the examination of organic residues prepared from different localities at Heimefrontfjella, the freshwater green alga Botryococcus was found. Exceptionally well-preserved colonies of Botryococcus were recorded in several samples at two sections of Early Permian age, Lidkvarvet and Locality A. These colonies vary in form and stage of development. By analogy with observations on recent material the following palaeoecological conclusions are drawn: 1) varying environmental and climatic conditions over a length of time existed at Lidkvarvet, and 2) very short ephemeral aquatic conditions existed intermittently at Locality A.

Data on the distribution, abundance and population structure of krill in the Prydz Bay area during January–February 1985 are considered in relation to hydrography and phytoplankton standing stocks. Stratified mean density and biomass estimated for the whole surveyed area from RMT-8 hauls were among the lowest recorded (3.3 individuals 1000 m−3 and 3.1 g 1000 m−3) confirming Prydz Bay as a low krill abundance area in the Southern Ocean. Age cohorts 1+ to 4+ were present, the size of the animals increased from south to north and juveniles were mostly found in surface waters near the pack-ice. Adults were in an active reproductive phase: 98% of the females were mated and 35% were ready to spawn whereas 86% of the males carried spermatophores. Breeding was taking place in oceanic waters over deep zones with the spawning season limited to January-April. Phytoplankton biomass was also very low in the area (mean of 29 mg Chl a m−2 in the upper 200 m) and currents speed low, never reaching 10 cm s−1. Krill distribution was strongly related to water circulation pattern but not related to phytoplankton distribution.