We add comments to a recent series of publications in peer-reviewed journals concerning the distribution of large Antarctic toothfish (Dissostichus mawsoni) found over the inner shelf of the Ross Sea. We note that earlier fish ecologists advanced innovative hypotheses invoking physical–biological interactions with life history, and that these, far from being disproved, have been relegated by more immediately pressing management concerns. We argue that, despite the considerable advances achieved by research groups working on D. mawsoni, an understanding of distribution and abundance is incomplete without reference to the physical structure that supports their life history. We briefly consider hypotheses highlighted by the recent literature in the context of major features of the shelf circulation in the Ross Sea, in particular intrusions of modified Circumpolar Deep Water along trough systems. We suggest physical–biological interactions that may be involved and call for improvements in the monitoring programme that can help test between the competing hypotheses.

Population growth of the southern giant petrel Macronectes giganteus from South America has been linked with an increase in fishing activities. It was demonstrated recently that a population from Elephant Island, Antarctic Peninsula, largely overlaps its non-breeding distribution with zones of high fishing intensity off South America. This study investigated the assumption that the increase in this population since the 1980s is related to an increase in fisheries off South America. Our results show that the population size is proportional to the increase in demersal and squid fisheries. These fisheries produce a considerable amount of discards, which can be used by non-breeding southern giant petrels as a food source during unfavourable conditions in winter. This may enhance the adult survival rates with potential carry-over effects on population size. Our study shows that we need to further understand the effects of fishery discards/offal on scavenging seabirds of the Southern Ocean, and highlights the importance of understanding the carry-over effects of seabird–fisheries interactions during the non-breeding phase in population dynamics.

Adélie penguins (Pygoscelis adeliae) are responding to ocean–climate variability throughout the marine ecosystem of the western Antarctic Peninsula (WAP) where some breeding colonies have declined by 80%. Nuclear and mitochondrial DNA (mtDNA) markers were used to understand historical population genetic structure and gene flow given relatively recent and continuing reductions in sea ice habitats and changes in numbers of breeding adults at colonies throughout the WAP. Genetic diversity, spatial genetic structure, genetic signatures of fluctuations in population demography and gene flow were assessed in four regional Adélie penguin colonies. The analyses indicated little genetic structure overall based on bi-parentally inherited microsatellite markers (FST =-0.006–0.004). No significant variance was observed in overall haplotype frequency (mtDNA ΦST =0.017; P=0.112). Some comparisons with Charcot Island were significant, suggestive of female-biased philopatry. Estimates of gene flow based on a two-population coalescent model were asymmetrical from the species’ regional core to its northern range. Breeding Adélie penguins of the WAP are a panmictic population and hold adequate genetic diversity and dispersal capacity to be resilient to environmental change.

High-performance thin layer chromatography was performed to investigate the potential presence of four phthalic acid esters, dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and dioctyl phthalate (DEHP), in Antarctic krill. The results revealed that in freeze-dried Antarctic krill levels of DBP (0.1043±0.0005 mg g-1 (104.3±0.05 mg kg-1)) were high. The structure of DBP in Antarctic krill was determined by gas chromatography-mass spectrometry. Its existence is of concern based on demonstrated harmful effects to animals and plants as Antarctic krill is a key part of the food chain in Antarctic coastal marine ecosystems. The adverse effects of DBP on Antarctic krill and the source of DBP should be explored in further research.

Within Antarctica there are large gradients both in climate and in vegetation which offer opportunities to investigate links between the two. The activity (% total time active) of lichens and bryophytes in hydric and xeric environments was monitored at Livingston Island (62°39'S). This adds a northern site with a maritime, cloudy climate to previous studies in the southern Antarctic Peninsula and the Dry Valleys (78°S). Annual activity increases northwards from less than 1% to nearly 100%. There is a major and consistent difference between hydric sites which, with snow melt, can be 100% active in summer months even in the Dry Valleys, and xeric sites which, depending on precipitation, rarely exceed 80% activity even at Livingston Island. Mosses dominate hydric sites and lichens the xeric sites all along the gradient. Mean temperatures when active are 2–4°C at all sites, as liquid water is required. Light is a potential major stress reaching 880 µmol m-2 s-1 when active in continental sites. The lack of extremes in temperatures and light combined with high activity levels means that summer at Livingston Island is one of the better sites for lichen and bryophyte growth in the world.

Biogeographical patterns among deep sea benthic communities in the Drake Passage remain poorly understood as a consequence of poor sampling resolution and the spatial remoteness of many sea floor features. Hard-bottom features, including at least 20 seamounts, remain uncharacterized with respect to their benthic megafaunal community assemblages. Here, we present community assemblage patterns from several locations across the Drake Passage to better understand the faunal relationships between deep sea floor communities in the region. Towed camera surveys were conducted on nine topographical features ranging from shelf environments on the southern Chilean Margin, the western Antarctic Peninsula shelf and seamounts in the central Drake Passage. These are the first quantitative measurements of megafaunal abundance at two seamount complexes in the central Drake Passage and multivariate analyses are used to examine the factors influencing species distributions. Three biogeographical groupings were identified based on species assemblages and environmental variables specific to major water mass boundaries in the region: sub-Antarctic Mode Water (318–523 m), Antarctic Intermediate Water (504–1128 m) and Circumpolar Deep Water (1837–3034 m). Further examination of megafaunal associations between sea floor structures may provide clues as to how sub-Antarctic communities are connected throughout the greater Southern Ocean.

A 9.24 m sediment core, GA-2, was collected on the coastal platform of Grande Valley, a relatively narrow and shallow fjord in Fildes Peninsula, King George Island, Antarctica. The sediment was formed between 6600 and 2000 cal. yr bp according to accelerator mass spectrometry (AMS) 14C dating of five bulk sediment samples. The comprehensive proxy indicators (grain size, loss on ignition at 550°C, magnetic susceptibility, elements) were analysed, and three separate depositional environments and an alternating climate change pattern were identified. Grande Valley experienced a warm marine environment between 6600 and 5800 cal. yr bp, a minor cooling between 5800 and 4800 cal. yr bp, the transition from cool to warm during 4800–4400 cal. yr bp, a mid-Holocene climatic optimum between 4400 and 2700 cal. yr bp, and the onset of the Neoglacial at 2700 cal. yr bp. This study reconstructed the environmental history of Grande Valley during the mid–late Holocene, provides the missing marine record of historical climate for the western coast of Fildes Peninsula and lays the foundation for further study of the climate and environment changes therein. Our finding that the sea level was c. 12 m a.m.s.l. at 2000 cal. yr bp allows for detailed reconstruction of Holocene sea level variations.

We report here the discovery of a boulder pavement cropping out at the base of the Hobbs Glacier Formation (Miocene), on the northern sector of Seymour Island (Isla Marambio), West Antarctica, along the contact with the underlying La Meseta Formation (Eocene). The feature described has many points in common with boulder pavements developed in tidal-marine environments. The clasts of the pavement are mostly boulders and bear up to three sets of glacial striae on their bevelled truncated surfaces, but are not elongate parallel to them or bullet shaped. No diamictite body was identified associated with the boulder pavement. These features differ from those of boulder pavements described from terrestrially glaciated Cenozoic deposits and may indicate a shallow glaciomarine environment for the late Cenozoic of Seymour Island.

Microwave radiometer SSM/I (Special Sensor Microwave Imager) data and scatterometer QuikSCAT (Quick Scatterometer) data have been widely used for near-surface snow melt detection based on their sensitivity to liquid water present in snow. The SSM/I data have high reliability and the QuikSCAT data have high spatial resolution. In order to improve the accuracy of Antarctic near-surface snow melt detection, we propose a new method based on the synergy of SSM/I and QuikSCAT data, i.e. the snow melt physical model incorporates the complementary advantages of both datasets. Based on comparisons with temperature data from three automatic weather stations, the proposed algorithm improved the accuracy of snow melt detection. The algorithm could also be applied to other regions, which would provide further evidence to support its use and additional data to document changes in the Antarctic due to global climate change.