In the summer of 1995/96, 25 southern elephant seals, Mirounga leonina, were stomach lavaged at Stranger Point, King George Island, South Shetland Islands. Cephalopod remains were present in 72% of the individuals sampled (n = 18). Seven species of squid and three of octopus were identified. The squid Psychroteuthis glacialis was the most important prey in terms of numbers (77%), biomass (80.8%) and frequency of occurrence (94.4%). Next in importance in terms of mass was the squid Alluroteuthis antarcticus (7.8%) in the diet of females and the octopodid Pareledone ?charcoti in the diet of males (13.2%). Females preyed on a wider variety of squid taxa than males (7 vs 3) but octopodids occurred only in stomach contents from males. The predominance of P. glacialis in the prey of the South Shetland Islands elephant seals can be explained by the southerly location of the foraging areas of this population compared to South Georgia, Heard and Macquarie islands, where the diet of southern elephant seals has previously been analysed. Psychroteuthis glacialis is the predominant squid in waters close to the Antarctic continent.

The current status of Antarctic Odontocetes – sperm whales Physeter catodon, killer whales Orcinus orca, long-finned pilot whales Globicephala melaena, hourglass dolphins Lagenorhynchus cruciger and poorly known species of beaked whales (family Ziphiidae)–were studied in Anatarctic waters using data gathered in sighting surveys conducted from 1976/77 to 1987/88. Temporal variation in density demonstrated the different migration patterns by species, especially between sperm whale and killer whale. Spatial distributions during mid-summer demonstrated different peaks of occurrence for each species by latitude that suggest possible segregation between the species. Killer whales occur mainly in the very southernmost areas, sperm whales in the southern half of the study area, beaked whales (mostly southern bottlenose whales Hyperoodon planifrons) ranged over a wide area, and long-finned pilot whales and hourglass dolphins were mainly in the northern regions of Antarctic waters. Several longitudinal peaks of occurrence and apparent distribution gaps were identified for sperm, beaked and killer whales. Abundance estimates for south of the Antarctic Convergence in January are based on line transect theory and were 28 100 animals (coefficient of variation CV 0.18) sperm whales, 599 300 (0.15) beaked whales (mostly southern bottlenose whales), 80 400 (0.15) killer whales, 200 000 (0.35) long-finned pilot whales, and 144 300 (0.17) hourglass dolphins. Based on this, biomass of these species were estimated as 0.77 (sperm whales), 2.70 (beaked whales), 0.32 (killer whales), 0.16 (long-finned pilot whales) and 0.01 (hourglass dolphins) million tonnes. Consumption of food (mostly squid) by the Odontocetes is estimated as 14.4 million tonnes with 67% of the total consumed by beaked whales. Indirect consumption of Antarctic krill through the predation of squid by beaked whales is estimated to be c. 24 million tonnes. This value is similar to the estimate of krill consumption by penguins in the Antarctic (33 million tonnes). Odontocetes, especially southern bottlenose whales, are suggested to have a much greater role in the Antarctic ecosystem than has previously been considered.

We studied the influence of the semi-annual oscillation (SAO) on near-surface temperatures in Antarctica, using observations of 27 stations that were operational during (part of) the period 1957–79. For the annual cycle of surface pressure, the second harmonic explains 17–36% of the total variance on the Antarctic Plateau, 36–68% along the East Antarctic coast and almost 80% on the west coast of the Peninsula, and decreases further to the north. As a result of the amplification of the wave-3 structure of the circulation around Antarctica, a significant modification of the seasonal cooling is observed at many stations. The magnitude of this modification is largely determined by the strength of the temperature inversion at the surface: the percentage of the variance explained by the second harmonic of the annual temperature cycle is then largest on the Antarctic Plateau (11–18%), followed by the large ice shelves and coastal East Antarctica (6–12%) and stations at or close to the Peninsula (0–5%). A significant coupling between the half-yearly wave in surface pressure and that in surface temperature is found for coastal East Antarctica, which can be directly explained by the changes in meridional circulation brought about by the SAO. We show that the coupling of Antarctic temperatures to the meridional circulation is not only valid on the seasonal time scale of the SAO, but probably also on daily and interannual time scales. This has important implications for the interpretation of time series of Antarctic temperatures, a problem that will be addressed in part 2 of this paper.

Antarctic soil chronically exposed to gas-oil was analysed in order to isolate and study the growth conditions of hydrocarbon degrading bacteria. Soil samples taken near the shoreline in Jubany Station (King George Island, South Shetland Islands) were used as inoculum in liquid culture media with crude oil as sole carbon source. A psychrotrophic Acinetobacter strain was isolated and selected for further investigations. Effects were studied of temperature, initial pH, NaCl concentration and different chemical structure of the hydrocarbon on growth. Degradation rate was determined with n-dodecane and n-hexadecane. Growth of Acinetobacter ADH-1 showed no differences at an initial pH of 7.0, 7.5 and 8.0. Optimum temperature ranged between 25–30°C but the strain was capable of growing on n-dodecane at 4°C. Growth was observed in the presence of 3.5% NaCl. A decrease in the surface tension values was observed in the culture broth during the first 20 h of incubation (from 68 din cm−1 to 31 din cm−1). This proved to be related to the cellular fraction of the culture. The study shows that Acinetobacter ADH-1 is a psychrotrophic bacteria able to grow with hydrocarbons as sole carbon and energy source and could be potentially useful to design bioremediation processes in temperate and cold climate areas.

The seasonal changes of the nutrient regime and the development of algal communities in snow-covered fast ice and the underlying platelet layer was investigated in the eastern Weddell Sea during autumn, winter, and spring 1995. In the upper sea ice, an autumnal diatom community became enclosed during subsequent ice growth in winter, declined, and was replaced by a flagellate dominated community in spring. In this layer, nitrate was completely exhausted at the end of spring, although nutrients had been partly regenerated in early spring. The progressive congelation of platelet ice contributed significantly to sea ice growth thus influencing algal inoculation of the sea ice bottom. Biomass, present in the uppermost section of the platelet layer, could be found in the sea ice bottom after this section congealed to solid ice. After incorporation, species composition changed from larger and chain-forming species to species of smaller cell size. Concurrently, net growth rate slowed down from 0.07 day−1 within the platelet layer to 0.03 day−1 within the sea ice. Despite a thick snow cover of more than 20 cm, maximum biomass yield was 210 mg chl a m−2 in the platelet layer and 40 mg chl a m−2 in the sea ice respectively, while 95% of the latter was located within consolidated platelet ice. Total fast ice biomass observed here is significantly lower than that observed in snow-free fast ice of the Ross Sea, but because snow cover of the southern Weddell Sea is representative of most fast ice areas in the Antarctic, the data presented here are of general value.

The Amundsen Sea embayment is a probable site for the initiation of a future collapse of the West Antarctic Ice Sheet. This paper contributes to a better understanding of the transport pathways of subglacial sediments into this embayment at present and during the last glacial period. It discusses the clay mineral composition of sediment samples taken from the seafloor surface and marine cores in order to decipher spatial and temporal changes in the sediment provenance. The most striking feature in the present-day clay mineral distribution is the high concentration of kaolinite, which is mainly supplied by the Thwaites Glacier system and indicates the presence of hitherto unknown kaolinite-bearing sedimentary strata in the hinterland, probably in the Byrd Subglacial Basin. The main illite input is via the Pine Island Glacier. Smectite originates from the erosion of volcanic rocks in Ellsworth Land and western Marie Byrd Land. The clay mineral assemblages in diamictons deposited during the last glacial period are distinctly different from those in corresponding surface sediments. This relationship indicates that glacial sediment sources were different from modern ones, which could reflect changes in the catchment areas of the glaciers and ice streams.

In order to reconstruct past changes in penguin populations we performed geochemical analyses on a penguin ornithogenic sediment core DG4 retrieved from a lake catchment on Gardner Island, Vestfold Hills. P, Se, F, S, As, Sr and Cu in DG4 were identified as the bio-element assemblage by R-clustering analyses on the elemental concentrations and comparisons with those in bedrock and fresh penguin guano. Factor analysis on the levels of these bio-elements in the core permitted a reconstruction of variations in historical penguin populations at Gardner Island spanning the past 8500 years. The penguin population showed significant fluctuations, reaching its highest density between 4700–2400 calibrated years before present. This coincides with evidence for a late Holocene warm period in the Vestfold Hills, similar to that associated with the late Holocene penguin optimum recorded in the Ross Sea and Antarctic Peninsula regions.

In an attempt to improve the understanding of the natural variability and distribution of trace elements in Antarctic organisms, the concentrations of arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, vanadium and zinc in representative benthic species from two pristine coastal environments were measured and compared with literature data for other uncontaminated coastal ecosystems. Correlations between the elements, differences between the species and between the sampling sites were examined by principal component analysis. Metal accumulation was particularly evident in the tissues of the sea star Odontaster validus, the bivalve mollusc Laternula elliptica and in the red alga Phyllophora antarctica. However, metal accumulation was not the same for all the analytes, but, rather, depended on the organism characteristics. In particular, the soft tissues of Odontaster validus were characterized by high concentrations of cadmium, zinc and copper, those of Phyllophora antarctica by high concentrations of manganese and nickel, and the tissues of Laternula elliptica by high concentrations of all measured elements, particularly in its digestive gland. The Antarctic data as well as those reported for other pristine coastal ecosystems showed remarkably high natural variability in metal content, which must be taken into account when interpreting results from biomonitoring programmes.

The Rauer Islands contain more than fifty shallow lakes and small ephemeral ponds. Despite their proximity to the Vestfold Hills - one of the most diverse and intensively studied lake districts of eastern Antarctica - the lakes of the Rauer Islands have remained undescribed. In this study the physical and chemical limnology and biology of ten lakes is presented and their species-environment relationships explored using multivariate statistics. Analyses of chemical and biological data indicate that the Rauer Islands form a distinct limnological province amongst the lakes of the Prydz Bay oases. Salinities range from hypo- to hyper-saline with an ionic order close to that of seawater. Deviance from this order indicates either an earlier origin for some of the most hypersaline lakes when compared with the Vestfold Hills, more rapid evaporation vs precipitation or differences in the sources of ions resulting from isostatic history. With fluctuating salinities, winter water temperatures below –10°C, seasonal ice and slush formation, desiccation and high levels of solar radiation, the lacustrine environment presents considerable abiotic challenges for biological survival. Results indicate that there is little or no planktonic flora in the lakes and no zooplankton were encountered. Despite this, analyses of pigments, diatoms and other micro-algae revealed an active and diverse benthic biota characterized by filamentous cyanobacteria with interstitial algae. Thirty-eight diatom taxa, and a selection of Chlorophyta and Xanthophyta were detected amongst the cyanobacteria. Clusters in the diatom data correspond to salinity. Further analyses of the relationships between the biota and their environment revealed some of the strategies employed for survival. In particular, the synthesis of scytonemin was detected. This pigment is known to function as an extracellular UV sunscreen which protects cyanobacterial cells against damage by ultraviolet radiation. These results support the hypothesis that environmental extremes and biogeographical isolation control the biology of these lakes.

Photosynthetic photon flux density (PPFD), air relative humidity and thallus temperature (TT) were measured in Usnea antarctica over a period of 12 months at a coastal rock on King George Island, South Shetland Islands. TT had an annual amplitude of c. 54 K with the maximum of +27.4°C recorded in December and minimum of −27.3°C in July. Daily maximum TT exceeded 0°C every month except in June and July when they were below −0.4°C and −1.6°C, respectively. Daily minimum temperatures were always below zero. Diel courses of PPFD showed pronounced seasonal differences between summer (more than 2000 μmol m−2s−1) and winter (less than 50 μmol m−2s−1 in July). Daily sum of PPFD was highest (more than 30 mol m−2d−1) in December and lowest (0.1 mol m−2d−1) in July. A photosynthesis model was used to estimate the potential annual primary production from habitat PPFD and TT. The estimated potential annual carbon balance of U. antarctica was 323 mg CO2 g−1 dry weight y−1 assuming that the lichen was always at optimal moisture. The potential carbon balance indicates that primary production is severely limited by low PPFD and subzero TT in the austral winter. Nevertheless, the PPFD and TT would allow metabolic activity during winter but with a negative carbon balance during May–August. Spring and autumnal months are revealed as probably the most important periods for lichen primary production because PPFD exceeds photosynthetic light compensation point during the daytime and ambient moisture conditions frequently favour a positive carbon balance.

The Antarctic silverfish Pleuragramma antarcticum Boulenger is the dominant fish species in the high Antarctic zone, playing a key role in the Ross Sea midwater shelf ecosystem. Unlike other notothenioids, it is holoplanktonic species, spending its entire life cycle in the water column. Early life stages of P. antarcticum are generally found in the upper 200 m and their spatial distribution is largely affected by water masses and general circulation. To understand better the mechanisms involved in the geographical distribution of the Antarctic silverfish within the western Ross Sea, an analysis of abundance and distribution was carried out in relation to oceanographic conditions. Samples were collected in summer during the 1998, 2000 and 2004 Italian cruises, covering the majority of the western sector of the Ross Sea. Overall 127 stations were sampled using standard plankton nets for biological samples and CTD and XBT to record abiotic parameters. Although all surveys were in December–January, the yearly results differed in terms of relative abundance of larval developmental stages and of oceanographic characteristics. The 1997–98 samples were characterized by very low abundance overall and by the virtual absence of early larvae. In summers 1999–2000 and 2003–04 the abundance of P. antarcticum was one order of magnitude higher than in the earlier season. In 1999–2000 catches were mainly composed of pre-flexion larvae and late postlarvae, while in 2003–04 catches were made up of pre-flexion larvae and juveniles. In January 2000 the Ross Sea summer polynya was fully open as the pack ice was almost completely melted, whereas in January 1998 and 2004 the opening of the polynya was considerably delayed. As a consequence, a delay in phytoplankton blooms and a decrease in primary production were observed in the summer seasons 1998 and 2004 with respect to 2000. The spatial distribution of early life stages, that were confined to the continental shelf and shelf break of the Ross Sea, generally appeared to be positively influenced by transition zones (oceanographic fronts). In addition, most of catches were recorded on or in close proximity to the banks (Pennell, Mawson, Ross and Crary) that characterize the continental shelf of the Ross Sea. On the basis of present findings and literature data, a link between the general circulation in the western Ross Sea and the distribution pattern of the early life stages of P. antarcticum has been developed.

As baleen whales recover from severe exploitation, they are probably subject to a wide variety of threats within the Antarctic marine ecosystem, including directed take. Here we review both the management and current status of Antarctic baleen whales and consider those threats likely to impact on them. Threats range from global problems - marine pollution and climate change - to localized issues including shipping, habitat disturbance, unregulated wildlife tourism and fishery activities. We identify the most pressing anthropogenic threats to baleen whales including scientific whaling and climate change. It is unclear whether current management approaches will be able to effectively encompass all these threats while also accounting both for the differing levels of scientific understanding and for the differing recovery rates of the whale species. For management we recommend the following: 1) incorporation of both ecosystem considerations and the suite of identified threats not limited to direct take, 2) identification of measurable indicators of changes in whales that allow more certainty in monitoring of populations and the environment, and 3) recognition of significant relationships between baleen whales and habitat features to provide information on distribution and use.

The synoptic origins of precipitation on the western side of the Antarctic Peninsula over the one year period March 1992 to February 1993 are investigated using meteorological observations, satellite imagery and analyses produced by the UK Meteorological Office. Precipitation at Rothera Station was found to occur at 30% of the synoptic reporting time with 80% of precipitation reports being associated with cyclonic disturbances. Although three quarters of all precipitation reports were for snow, the proximity of Rothera to the zone of maximum cyclonic activity meant that incursions of mild air produced rain in all seasons. During the year 95% of all precipitation was classed as slight. Variability of precipitation on the intraseasonal timescale was highly dependent on the synoptic-scale circulation. The most common synoptic situation for precipitation was a frontal cyclone over the Bellingshausen Sea which accounted for 38% of all precipitation events and 62% of the moderate and heavy precipitation reports. Of the extra-tropical cyclones that gave precipitation 49% were found to have developed south of 60°S. None of the precipitation at Rothera was attributable to mesocyclones. Snow stake measurements from Rothera were a poor indicator of precipitation as a result of blowing snow.

Field measurements of CO2 exchange were made with an infra-red gas analyser system on lichens at Bailey Peninsula, Wilkes Land, continental Antarctica. It has been demonstrated that Usnea sphacelata, a prominent element of the cryptogamic vegetation of this area, became photosynthetically active at temperatures below 0°C when the thalli were covered by drifted snow. Carbon dioxide uptake was detected down to −10°C. The carbon production during such a ‘frost’ day was considerable for a slow-growing Antarctic lichen. The importance of snow for production in lichens is emphasized. The mechanism of water uptake when the thalli are frozen needs further investigation.

Recent rapid retreat of glacial front lines and the loss of land ice along the Antarctic margins may play an important role in exporting suspended particulate matter (SPM) potentially rich in bioavailable (defined as ascorbate leachable) iron (FeA) to coastal areas of the Southern Ocean. Sediment ablation is an additional source of iron for this high-nutrient low-chlorophyll region. In Potter Cove, King George Island, meltwater streams discharge up to 18 000 mg l-1 (average 283 mg l-1) of slightly weathered, finely ground bedrock particles into coastal waters during the summer. Approximately 15% of this SPM is exported within a low-salinity surface plume into Bransfield Strait. Based on our data, an estimated 12 mg m-2 yr-1 of FeA is exported from the South Shetland Island land surface (ice-free and subglacial areas) to the surrounding coastal waters. Extrapolated to an area of 2.5x104 km2, this FeA input is comparable to the contribution from icebergs and c. 240-fold higher than aeolian input via dust. An observed rise in local sediment accumulation rates suggests that glacial erosion has been increasing over recent decades and that (sub-)glacially derived SPM is becoming more important as a source of iron to the Southern Ocean.

Soil samples from eight sites at Marble Point and Pram Point, McMurdo Sound region, contaminated by human activities were examined for heavy metal content, using sequential extraction methods. The redistribution of lead, zinc and copper arising from point sources of these metals was demonstrated. The levels found are not considered to represent serious pollution but do indicate that human activities can change the chemistry of the Antarctic environment in localized areas.

Nearshore marine benthic algal communities along the western Antarctic Peninsula harbour extremely high densities of amphipods that probably play important roles in nutrient and energy flow. This study extends our evaluation of the importance of amphipods in the nearshore Antarctic Peninsular benthic communities and focuses on sponge associations. We found a mean density of 542 amphipods per litre (L) sponge for twelve species of ecologically dominant sponges. The highest mean density (1295 amphipods per L sponge) occurred with Dendrilla membranosa Pallas. The amphipod community associated with the 12 sponges was diverse (38 species), with mean species richness values ranging from two to eight species. Mean Shannon diversity indices (H’) ranged from 0.52 to 1.49. Amphipods did not appear to have obligate host relationships. Qualitative gut content analyses indicated that 12 of the 38 amphipod species were found with sponge spicules in their guts. However, only one of the amphipods, Echiniphimedia hodgsoni Walker, had considerable amounts of spicules in the gut. Organic lipophilic and hydrophilic extracts of the twelve sponges were presented in alginate food disks to a sympatric omnivorous amphipod in feeding bioassays and extracts of only two sponges deterred feeding.

Branches, stems and roots of Nothofagus (southern beech) were reported from the Beardmore Glacier area (Sirius Formation) some 500 km from the South Pole. The Sirius Formation is a glacially derived unit which is considered Pliocene in age. We considered two scenarios by which a Nothofagus forest could flourish so close to the South Pole during the Pliocene. One scenario calls for the disappearance of this genus from Antarctica during the early Tertiary (Oligocene) and its re-introduction during a warm Pliocene interval. Seeds from modern Nothofagus, however, are not viable after submersion in sea water, are not carried by migrating birds and are not designed for long-distance wind transport. The second scenario involves survival of Nothofagus in Antarctic refugia through middle Tertiary glacial advances and its flourishing during a Pliocene warming. Excluding its occurrence in the Beardmore Glacier area, the known range of this genus in Antarctica is Cretaceous to Oligocene with some questionable occurrences in the early Miocene. The existing data do not support the refugia scenario. We also considered published speculations in which the closest modern analogue to the Beardmore Glacier Region, during the time that the Nothofagus represented by these specimens lived, was the coastal region of southern Chile where average annual temperatures are approximately 5°C and summer temperatures are of the order of 8–10°C. We incorporated these observations and speculations into a palaeoenvironmental model, assuming them to be valid; the results require Pliocene temperatures as warm as, or warmer than, the Cretaceous, a scenario which is not supported by the literature. We conclude, therefore, that the occurrence of Nothofagus in the Beardmore Glacier area is older than Pliocene. Instead, we suggest that it represents a relict assemblage which is probably no younger than Oligocene but which may have persisted into the early Miocene.

The fluorescent neutral lipid stain, nile red, was used to examine cell-specific neutral lipid levels in natural assemblages of Antarctic sea ice microalgae. Neutral lipid:chlorophyll, neutral lipid:particulate carbon (PC) and neutral lipid:particulate nitrogen (PN) ratios were highest in communities dominated by Nitzschia spp. and Navicula glaciei van Heurck. The lowest specific neutral lipid content was estimated in the congelation ice samples dominated by the diatom Amphiprora spp., and in surface assemblages dominated by Phaeocystis pouchetii Hariot and the dinoflagellate Gymnodinium sp. Scatter plots of neutral lipid on PC and PN, which included data from all assemblages, showed that assemblages dominated by P. pouchetii and Amphiprora spp. clustered near the origin reflecting their relatively lower specific neutral lipid levels, compared with assemblages dominated by N. glaciei and Nitzschia spp. Cellular PC:PN was significantly (P<0.001) lower in microalgae inhabiting surface melt pools or tide cracks compared to those associated with congelation or platelet ice.

The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project will test the overarching hypothesis that an active hydrological system exists beneath a West Antarctic ice stream that exerts a major control on ice dynamics, and the metabolic and phylogenetic diversity of the microbial community in subglacial water and sediment. WISSARD will explore Subglacial Lake Whillans (SLW, unofficial name) and its outflow toward the grounding line where it is thought to enter the Ross Ice Shelf seawater cavity. Introducing microbial contamination to the subglacial environment during drilling operations could compromise environmental stewardship and the science objectives of the project, consequently we developed a set of tools and procedures to directly address these issues. WISSARD hot water drilling efforts will include a custom water treatment system designed to remove micron and sub-micron sized particles (biotic and abiotic), irradiate the drilling water with germicidal ultraviolet (UV) radiation, and pasteurize the water to reduce the viability of persisting microbial contamination. Our clean access protocols also include methods to reduce microbial contamination on the surfaces of cables/hoses and down-borehole equipment using germicidal UV exposure and chemical disinfection. This paper presents experimental data showing that our protocols will meet expectations established by international agreement between participating Antarctic nations.