Uncertainty exists over the importance of Antarctic toothfish (Dissostichus mawsoni) as prey of top predators in the Ross Sea. In this paper we assess relative weight given to direct, observational evidence of prey taken, as opposed to indirect evidence from scat and biochemical analysis, and conclude that toothfish are important to Weddell seals (Leptonychotes weddellii). The seals eat only the flesh of large toothfish and therefore they are not detected in scat or stomach samples; biochemical samples have been taken from seal sub-populations where toothfish seldom occur. Using direct observations of non-breeding seals away from breeding haulouts in McMurdo Sound, 0.8–1.3 toothfish were taken per day. Based on these and other data, the non-breeding portion of the McMurdo Sound seal population, during spring and summer, consume about 52 tonnes of toothfish. Too many unknowns exist to estimate the non-trivial amount consumed by breeders. We discuss why reduced toothfish availability to Weddell seals, for energetic reasons, cannot be compensated by a switch to silverfish (Pleuragramma antarcticum) or squid. The Ross Sea toothfish fishery should be reduced including greater spatial management, with monitoring of Weddell seal populations by CCAMLR. Otherwise, probable cascades will lead to dramatic changes in the populations of charismatic megafauna.

In order to establish the environmental status of areas close to Antarctic stations it is necessary to document levels of contaminants present in these sites. Several petrogenic and pyrogenic sources have been reported for polycyclic aromatic hydrocarbons (PAHs) in Antarctica. In this work, levels of 25 PAHs were measured in suspended particulate matter (SPM), surface sediment and marine organisms (fish Notothenia coriiceps, bivalve Laternula elliptica and gastropod Nacella concinna) from Potter Cove. Total PAH levels from SPM were low and similar in all sites studied (30–82 ng g-1 dw), phenanthrene being the dominant compound (68–84%). The exception was an area close to the wharf where significantly higher values of light PAHs such as naphthalene, acenaphthylene, 2,3,5-trimethylnaphthalene and fluorene were detected, indicating the influence of recent fuel spills. PAH concentrations in surface sediments were generally low (37–252 ng g-1 dw) except for two sites (1762 and 1908 ng g-1 dw) which suggested an accumulation process associated with the water circulation pattern. Liver tissue of N coriiceps presented significantly higher PAH levels (257 ng g-1 dw) compared with gonads. The pattern of individual compounds from substrates and organisms suggests a petrogenic and low-temperature combustion origin.

Despite several works that have documented patterns of diversity in deep sea organisms, trends of diversity and the processes responsible for such trends still remain unclear. To date very few studies have documented the effects of variables such as latitude and longitude in deep-sea organisms in the Antarctic region. We explored the spatial patterns of diversity of benthic gastropods and bivalves in an extensive region about 2200 km long and 500 km wide from the South Shetland Islands to the Bellingshausen Sea in West Antarctica. A total of 134 species from 54 sites was recorded. Alpha diversity and beta diversity (measured as Whittaker’s and Bray-Curtis similarity indices) were highly variable among areas. None of the species richness estimators measured as Sobs, Chao2, Jacknife1 and Jacknife2, stabilized towards asymptotic values in any area. The number of rare species was large with almost half of species represented by 1 or 2 individuals (41%) and most species (62%) restricted to 1 or 2 sites. The partial Mantel test revealed that similarity between sites increased with the decrease of depth differences, but not with horizontal separation.

Western Wright Valley, from Wright Upper Glacier to the western end of the Dais, can be divided into three broad geomorphic regions: the elevated Labyrinth, the narrow Dais which is connected to the Labyrinth, and the North and South forks which are bifurcated by the Dais. Soil associations of Typic Haplorthels/Haploturbels with ice-cemented permafrost at < 70cm are most common in each of these geomorphic regions. Amongst the Haplo Great Groups are patches of Salic and Typic Anhyorthels with ice-cemented permafrost at > 70 cm. They are developed in situ in strongly weathered drift with very low surface boulder frequency and occur on the upper erosion surface of the Labyrinth and on the Dais. Typic Anhyorthels also occur at lower elevation on sinuous and patchy Wright Upper III drift within the forks. Salic Aquorthels exist only in the South Fork marginal to Don Juan Pond, whereas Salic Haplorthels occur in low areas of both South and North forks where any water table is> 50 cm. Most soils within the study area have an alkaline pH dominated by Na+ and Cl- ions. The low salt accumulation within Haplorthels/Haploturbels may be due to limited depth of soil development and possibly leaching.

New reference gravity values are provided for gravity base stations at McMurdo Station and Scott Base. The new values are obtained by a relative survey including the Hut Point base station (an International Satellite Triangulation station; 77.8448°S, 166.6418°E; 982975.65 mGal) located 110 m north of Scott’s 1901 Discovery Hut at McMurdo Station. This site is the only remaining station tied by previous surveys to the now defunct SATGRAV base Station located in the former Building 57, which was, in turn, measured by an absolute meter in 1995. New values are 982970.41 mGal for the THIEL-1 Station (77.8490°S, 166.6794°E) at McMurdo Station, 982973.40 mGal for the MMD-N Station (77.8491°S, 166.7567°E) at Scott Base, and 982977.83 mGal for the newly established SBG-1 Station (77.8499°S, 166.7667°E) under the flagpole at Scott Base. Our difference values are very consistent with previous surveys, including Nakagawa’s value for MMD-N at Scott Base, which is within 0.2 mGal of our new value.

In situ cosmogenic 10Be exposure dating, radiocarbon determinations, salt and sediment geochemistry, and rock weathering observations indicate that parts of Larsemann Hills, East Antarctica have been subaerially exposed throughout much of the last glacial cycle, with the last glaciation occurring prior to 100 ka bp. Salt-enhanced subaerial weathering, coupled with a paucity of glacial erratics, made exposure age dating challenging. Rapid subaerial surface lowering in some places means that some exposure ages may underestimate the true age of deglaciation. Despite this uncertainty, the data are consistent with the absence of overriding by a thick ice sheet during the Last Glacial Maximum ∼20–18 ka bp.

The Weddell Sea is one of the key regions of the Southern Ocean with respect to climate as most of the Antarctic Bottom Water (AABW) that occupies the world ocean deepest layers is likely to originate from this region. This study applies the Optimum Multiparameter water mass analysis to the Weddell deep waters in order to investigate their distribution and variability. The dataset used is based on the WOCE repeat sections in the area (SR04 and A12) from 1984 to 1998. The mean water mass distribution is consistent with previous knowledge of the region, along with high interannual variability. Regarding the temporal variability, it seems that the years of maximum Weddell Sea Deep Water (WSDW) contribution correspond to the lowest levels of Weddell Sea Bottom Water (WSBW), and vice versa. In order to identify possible forcing mechanisms for such variability, the water mass temporal anomalies were compared with oceanic and atmospheric modes of variability in that region such as the Southern Annular Mode (SAM). An apparent correlation between the SAM index temporal gradients and WSBW anomalies indicate that the Weddell Sea export of dense waters to the world ocean may be linked to that index on several time scales.

This study estimates energy and mass balance at the edge of the Antarctic ice sheet close to a non-glaciated area. An automatic weather station was installed on the ice sheet, near an ice free area of Schirmacher Oasis in Dronning Maud Land, East Antarctica. Hourly snow-meteorological parameters were recorded and observed during the summer of the year 2007–08. Hourly radiative and turbulent energy fluxes were estimated at the ice surface. An ultrasonic sensor was used to measure accumulation or ablation at the glacier surface. Ground Penetrating Radar was also used to measure the changes in ice thickness at the observation point. The net radiative flux was the main heat source and the latent heat flux was the main heat sink for the ice sheet with seasonal average values of 98 W m-2 and -86.7 W m-2 respectively. There was a high ablation rate for the ice sheet near the non-glaciated area with a seasonal mean of 0.0172 m w.e. per day. Over the period 10 November 2007–7 February 2008 the mass balance was -1.53 m w.e. Good correlation (r2 = 0.97) was observed between estimated and observed hourly ablation of the glacier. Sublimation and melt processes contributed 16.5% and 83.5% respectively to the net summer ablation.