A number of studies have suggested that high concentrations of organisms in sea ice may be the result of harvesting and concentration by frazil ice. Laboratory experiments have shown that frazil ice can concentrate organisms from two to four times above levels in the underlying water. The concentrations in nature, however, can be considerably higher. The apparent discrepancy between laboratory results and field observations can be explained by the longer temporal and spatial scales that allow more contact of ice crystals with particles and with one another in the sea. It is also likely that small-scale circulation features, such as Langmuir circulation, enhance the ability of frazil ice to concentrate organisms in a natural setting.

Seasonal variation of temperature, pressure, snow accumulation, winds, and their harmonic analysis are presented by using the data from Zhongshan Station and three Automatic Weather Stations deployed between the East Antarctic coast and the summit of the ice sheet at Dome A for the period 2005–07. Results show that: 1) temperature, snow accumulation and specific humidity decrease with increasing elevation and distance from the coast, with snow accumulation decreasing from 199 mm water equivalent (w.e.) yr-1 at LGB69 (180 km from the coast) to 31 mm w.e. yr-1 at Dome A, 2) Dome A experiences an extremely low minimum temperature of -82.5°C with the monthly mean temperature below -50°C for eight months in contrast to Zhongshan Station which does not show any monthly mean temperatures below -20°C, 3) mean surface wind speed increases from the coast to the escarpment region, and then reduces rapidly towards the interior plateau with the strongest winds occurring at katabatic sites with the greatest surface slopes, 4) temperature and pressure all shows a distinct biannual oscillation with a main minimum in spring and a secondary minimum in autumn, differing slightly from station to station, and 5) winter temperature corelessness increases as a function of elevation and distance from the coast, from 0.260 at the coastal Zhongshan Station to 0.433 at Dome A.

Reproductive allocation (reproductive biomass relative to vegetative biomass) and seed production were measured for samples of the two native phanerogams occurring in Antarctica. Material collected on South Georgia (subantarctic), Signy Island (northern maritime Antarctic) and Léonie Island (southern maritime Antarctic) allowed an initial comparison of reproduction over a wide latitudinal range. Sizes of vegetative and reproductive structures of Colobanthus quitensis were smaller in Signy Island samples than those from South Georgia or Léonie Island. This pattern was reflected in the pattern of seed production. Vegetative and reproductive structures of Deschampsia antarctica were generally similar in size at both maritime Antarctic sites, but larger at subantarctic South Georgia. Seed production was similar in each season assessed and at all three sites. In most samples of both species there were close relationships between reproductive and vegetative biomass, and seed output and reproductive biomass. Subantartic C. quitensis showed greater allocation to seed production than material from maritime Antarctic sites. D. antarctica showed the reverse pattern, with greater allocation to reproductive biomass and seed production in most samples of maritime Antarctic material, particularly those from Signy Island. Reproductive strategies do not form any specific adaptation to the Antarctic environment for these species. Reasons for the failure of other higher plants to become established in the maritime Antarctic are discussed, and it is concluded that geographical isolation is the main factor. The most important proximate factors influencing propagules which reach potential colonization sites are likely to be the short length and low temperature of the summer season in relation to the time required for establishment.

Ethanol extractable polyols and sugars from the dominant cryptogams of the Windmill Islands, Wilkes Land, East Antarctica, were characterized and quantified by gas liquid chromatography. Arabitol, ribitol and mannitol were the major low molecular weight carbohydrates extracted from all eight species of lichen analysed. Total extractable carbohydrate levels (20–60 mg g−1 dry weight) were comparable to those for temperate lichens. Extracts of four common bryophyte species were dominated by sucrose, glucose and fructose; little polyhydric alcohol was detected except in the liverwort Cephaloziella exiliflora which contained a substantial proportion of mannitol. Total carbohydrate levels in the bryophytes (9–60 mg g−1 dry weight) were comparable to those in lichens. The compositions of eight species of algae varied considerably. Prasiola crispa, Desmococcus vulgaris and Schizogonium murale possessed sorbitol as their main constituent and had extractable carbohydrate contents comparable to those found in bryophytes on a dry weight or chlorophyll a content basis. The one snow alga with comparable carbohydrate levels, Mesotaenium berggrenii, contained sucrose, glucose, glycerol and a number of unidentified compounds. The remaining four species (Oscillatoria sp., Chloromonas sp.1 and Chlorosarcina sp. 2 and Chlamydomonas pseudopulsatilla) did not accumulate comparable levels of sugars and polyols. Though the levels of these compounds were much lower in the Windmill Islands lichens than in maritime Antarctic species, their content with respect to water content (0.7–7 molal) was well above that at which cold acclimated plants accumulate these compounds (c. 100–500 millimolal), and which provide cryoprotection in vitro. In the case of the bryophytes and algae, however, the in vivo content was generally < 100 millimolal.

The Collaborative East Antarctic Marine Census (CEAMARC) surveys to the Terre Adélie and George V continental margin highlight the requirement for a revised high-resolution bathymetry model that can be used as a spatial tool for improving information on the physical environment of the region. We have combined shiptrack singlebeam and multibeam bathymetry, coastline data, and land and ice sheet topographic data to develop a new regional-scale bathymetry grid, called GVdem (short for George V digital elevation model). The GVdem grid spans an area between 138–148°E and 63–69°S, with a cell pixel size of 0.001-arcdegree (c. 100 m). The revised digital elevation model is a large improvement over previously available regional-scale grids from the area, and highlights seabed physiographic detail not formerly observed in this part of East Antarctica. In particular, the extent and complexity of the rugged inner-shelf valleys are revealed, and their spatial relationship with large shelf basins and adjacent flat-topped banks. The new grid also reveals further insight into the spatial distribution of the submarine canyons found on the continental slope.

This study contains the current list of the austral pycnogonids together with details of their depth range and distribution. To date 264 species have been recorded, accounting for 19.6% of the 1344 species recorded worldwide. One hundred and eight species are endemic to Antarctic waters, 62 to the sub-Antarctic, 63 are common in both regions, and 55 are circumpolar. The richest genus is Nymphon, with 67 species and the richest area is the Scotia Sea. Comparing species lists between the years 2000 and 2007 shows that increased expeditions with more sampling has increased the circumpolarity of species and decreased zonal endemicity. The benthic insular refuge hypothesis is proposed as an explanation for the southern distribution of the present pycnogonid fauna, with an origin in the Scotia Arc.

Lipid content, lipid class and fatty acid composition of four Southern Ocean cephalopod species – the myopsid Sepioteuthis australis and three oegopsids, Gonatus antarcticus, Moroteuthis robsoni and Todarodes spp. – were analysed. The lipid content of the digestive gland was consistently greater than that of the mantle, and was an order of magnitude greater in oegopsid species. The lipid class and fatty acid composition of the mantle and digestive gland also differed markedly in each species. Digestive gland lipid is likely to be of dietary origin, and large amounts of lipid in the digestive gland of oegopsids may accumulate over time. Thus the digestive gland is a rich source of fatty acid dietary tracers and may provide a history of dietary intake. However, the absolute amount of dietary lipid in the digestive gland of oegopsid species exceeds the absolute lipid content of mantle tissue. Therefore the overall lipid “signature” of an oegopsid may more closely resemble its prey species rather than its mantle tissue. When lipid techniques are used in dietary analysis of teuthophagous predators, squid may not be represented by a unique signature in analyses and their importance in the diets of predators may be underestimated.

Ninety-five percent of the fish species known from the Antarctic continental shelf and upper slope are acanthomorphs, i.e. spiny teleosteans. Notothenioids (suborder Notothenioidei) are acanthomorphs and so is their sister group. Unfortunately, until recently acanthomorph intra-relationships were so poorly known that it was necessary to sample all of this diversity just to search for a single sister group relationship. Using recent advances in acanthomorph molecular phylogenetics, particular properties of separate analyses and a new protocol of dataset combination, we identified a clade that contains the sister group of notothenioids, the Percidae (perches), and a number of relatives. Among these relatives are the Serranidae (sea basses), the genera Trachinus (weeverfish), Chelidonichthys (gurnard), Scorpaena (scorpionfish), and a group composed of the Zoarcoidei (eelpouts) and the Cottoidei (sculpins) with the Gasterosteidae (sticklebacks) as their sister group. Interestingly, that clade contains 88% of the fish species found on the Antarctic continental shelf and upper slope. The interrelationships of its components and their distribution show that the Antarctic benthic fish fauna has at least three origins.

The introduction of invasive species may be the most profound modern threat to biological communities in high-latitude regions. In the Southern Ocean, the natural transport mechanism for shallow-water marine organisms provided by kelp rafts is being increasingly augmented by plastic debris and shipping activity. Plastic debris provide additional opportunities for dispersal of invasive organisms, but dispersal routes are passive, dependent on ocean currents, and already established. In contrast, ships create novel pathways, moving across currents and often visiting many locations over short periods of time. Transportation of hull-fouling communities by vessel traffic thus poses the most likely mechanism by which exotic species may be introduced to the Southern Ocean.

Antarctic krill are a key species in the Southern Ocean ecosystem, and their life cycle appears to be correlated with, and by implication dependent upon, seasonal sea ice dynamics. Moving from correlations with environmental parameters to an understanding of the mechanisms that lead to these correlations may allow predictions of the consequences of climate change on the distribution of favourable habitat for Antarctic krill. During winter cruises in 2001 and 2002 in the region west of the Antarctic Peninsula, one of the most rapidly warming regions on the planet, ice camps were established for periods of 3–9 days. Timing of sea ice advance, chlorophyll a concentrations in ice cores, and growth rates and pigment content of larval krill all differed significantly between winters. Growth rates and pigment content of larval krill from the same ice floe were correlated, suggesting that growth rates in winter are a function of the biomass of the sea ice microbial community. Apossible mechanism underlying the correlation between recruitment success and timing of ice advance is proposed. In conjunction with other postulated habitat requirements, this proposed mechanism allows for speculation about future changes in the geographic location of favourable habitat for Antarctic krill.

This study describes the origin, bedrock geology, geomorphology, hydrological stability and physical and chemical characteristics of a representative set of 29 lakes in the ice-free parts of the Ulu Peninsula, James Ross Island, located close to the northern tip of the Antarctic Peninsula. Based on these features, six different types of lakes were defined: stable shallow lakes on higher-altitude levelled surfaces, shallow coastal lakes, stable lakes in old moraines, small unstable lakes in young moraines, deep cirque lakes and kettle lakes. We observed a significant relationship between lake type and water chemistry. Bedrock, lake age and morphometry together with altitude were the most important factors underlying the observed limnological variability. Our results further suggested possible nitrogen limitation in the lake ecosystems. However, physical factors such as low temperature and light were also likely to be limiting.

The Permian ended with the largest of known mass extinctions in the history of life. This signal event has been difficult to recognize in Antarctic non-marine rocks, because the boundary with the Triassic is defined by marine fossils at a stratotype section in China. Late Permian leaves (Glossopteris) and roots Vertebraria), and Early Triassic leaves (Dicroidium) and vertebrates (Lystrosaurus) roughly constrain the Permian–Triassic boundary in Antarctica. Here we locate the boundary in Antarctica more precisely using carbon isotope chemostratigraphy and total organic carbon analyses in six measured sections from Allan Hills, Shapeless Mountain, Mount Crean, Portal Mountain, Coalsack Bluff and Graphite Peak. Palaeosols and root traces also are useful for recognizing the Permian–Triassic boundary because there was a complete turnover in terrestrial ecosystems and their soils. A distinctive kind of palaeosol with berthierine nodules, the Dolores pedotype, is restricted to Early Triassic rocks. Late Permian and Middle Triassic root traces are carbonaceous, whereas those of the Early Triassic are replaced by claystone or silica. Antarctic Permian–Triassic sequences are among the most complete known, judging from the fine structure and correlation of carbon isotope anomalies.

In the summer 2000–01, thermal monitoring of the permafrost active layer within various terrestrial sites covered by lichen, moss or grasses was undertaken at Jubany (King George Island) and Signy Island in the Maritime Antarctic. The results demonstrated the buffering effect of vegetation on ground surface temperature (GST) and the relationship between vegetation and active layer thickness. Vegetation type and coverage influenced the GST in both locations with highest variations and values in the Deschampsia and Usnea sites and the lowest variations and values in the Jubany moss site. Active layer thickness ranged from 57 cm (Jubany moss site) to 227 cm (Signy Deschampsia site). Active layer thickness data from Signy were compared with data collected at the same location four decades earlier. Using a regression equation for air temperature versus ground surface temperatures the patterns of changing air temperature over time suggest that the active layer thickness increased c. 30 cm between 1963 and 1990 and then decreased 30 cm between 1990 and 2000. The documented increased rate of warming (2°C ± 1) since 1950 for air temperatures recorded in the South Orkney Islands suggests that the overall trend of active layer thickness increase will be around 1 cm year−1.

Changes in water mass distribution and horizontal circulation due to seasonal influences on the Ross Sea continental shelf are investigated using a circumpolar numerical model. An anticyclonic circulation cell that extends across the open shelf and into the ice shelf cavity is formed in the model. The increased east–west density gradient caused by the strong brine release in the Ross Sea polynya in winter results in an intensification of this anticyclonic cell from 1.5 Sv to 2.5 Sv. This supports the concept of a thermohaline-driven horizontal circulation on the Ross Sea continental shelf. In addition to a temporal change in the circulation strength, the changes in the density structure lead to complex temporal and spatial variability in the circulation around Ross Island. Due to seasonal variation in circulation strength and water temperatures, the area averaged basal melt rate of 25 cm a−1 shows a bimodal seasonal cycle ranging from 20–28 cm a−1, with maxima in March and August.

Hydrocarbon spills have occurred on Antarctic soils where fuel oils are utilized, moved or stored. We investigated the effects of hydrocarbon spills on soil temperature and moisture regimes by comparing the properties of existing oil contaminated sites with those of nearby, uncontaminated, control sites at Scott Base, the old Marble Point camp, and Bull Pass in the Wright Valley. Hydrocarbon levels were elevated in fuel-contaminated samples. Climate stations were installed at all three locations in both contaminated and control sites. In summer at Scott Base and Marble Point the mean weekly maximum near surface (2 cm and 5 cm depth) soil temperatures were warmer (P<0.05), sometimes by more than 10°C, at the contaminated site than the control sites. At Bull Pass there were no statistically significant differences in near-surface soil temperatures between contaminated and control soils. At the Scott Base and Marble Point sites soil albedo was lower, and hydrophobicity was higher, in the contaminated soils than the controls. The higher temperatures at the Scott Base and Marble Point hydrocarbon contaminated sites are attributed to the decreased surface albedo due to soil surface darkening by hydrocarbons. There were no noteworthy differences in moisture retention between contaminated and control sites.

A soil climate monitoring network, consisting of seven automated weather stations, was established between 1999 and 2003, ranging from Minna Bluff to Granite Harbour and from near sea level to about 1700 m on the edge of the polar plateau. Active layer depth was calculated for each site for eight successive summers from 1999/2000 to 2006/2007. The active layer depth varied from year to year and was deepest in the warm summer of 2001–02 at all recording sites. No trends of overall increase or decrease in active layer depth were evident across the up-to-eight years of data investigated. Average active layer depth decreased with increasing latitude from Granite Harbour (77°S, active layer depth of > 90 cm) to Minna Bluff (78.5°S, active layer depth of 22 ± 0.4 cm), and decreased with increasing altitude from Marble Point (50 m altitude, active layer depth of 49 ± 9 cm) through to Mount Fleming (1700 m altitude, active layer depth of 6 ± 2 cm). When all data from the sites were grouped together and used to predict active layer depth the mean summer air temperature, mean winter air temperature, total summer solar radiation and mean summer wind speed explained 73% of the variation (R2 = 0.73).

Quantitative and semi-quantitative samples of phyto- and zoobenthic organisms were collected by SCUBA diving at five stations along a depth transect from 0.5–16 m on the shallow hard bottoms off Terra Nova Bay, Ross Sea, Antarctica. The benthic associations were dominated by two macroalgal species (Iridaea cordata and Phyllophora antarctica) and by few animal taxa (mainly polychaetes, molluscs and peracarid crustaceans). Distribution at the community and species levels revealed a well-defined zonation pattern as a function of depth, governed mainly by sea ice scouring and melting. Zonation of vagile fauna was also affected by the effects of covering and architecture of the two dominant macroalgae. Species richness and diversity were higher in the Phyllophora-associated community, where habitat complexity and sheltering were higher. The highest faunal abundance (over 82 000 ind.m−2) and biomass (macroalgae and fauna wet weight 2392 g m−2) were recorded at 2 m depth in association with the Iridaea covering, where the harsher environmental conditions select a few taxa. The biomass values, even if underestimates of the whole community standing crop, are among the highest recorded in shallow austral biotopes. An autoecological and demographic analysis of the most abundant animal species revealed for some species (e.g. Laevilitorina antarctica and Paramoera walkeri) a quite complex population structure with up to three size classes, including juveniles. In some species, the cohort of juveniles showed a well-defined depth preference probably related to sheltering by the macroalgae. As a whole, the species analyzed showed various and contrasting reproductive strategies, despite the fact that the environmental conditions along the transect were relatively similar and quite selective.

We have determined the flux of calcium, chloride and nitrate to the McMurdo Dry Valleys region by analysing snow pits for their chemical composition and their snow accumulation using multiple records spanning up to 48 years. The fluxes demonstrate patterns related to elevation and proximity to the ocean. In general, there is a strong relationship between the nitrate flux and snow accumulation, indicating that precipitation rates may have a great influence over the nitrogen concentrations in the soils of the valleys. Aeolian dust transport plays an important role in the deposition of some elements (e.g. Ca2+) into the McMurdo Dry Valleys' soils. Because of the antiquity of some of the soil surfaces in the McMurdo Dry Valleys regions, the accumulated atmospheric flux of salts to the soils has important ecological consequences. Although precipitation may be an important mechanism of salt deposition to the McMurdo Dry Valley surfaces, it is poorly understood because of difficulties in measurement and high losses from sublimation.

The extensive ablation zone on the McMurdo Ice Shelf (78°S, 165°30′E) contains numerous ponds that are lined with benthic mats of cyanobacteria and associated micro-organisms. The photoautotrophic biomass content of these mats was examined in six contrasting ponds. Particulate carbon contributed only 3.2% of the mat dry weight, with C:N ratios generally less than 20:1. The chlorophyll a content was low relative to carbon (chlorophylla : C<0.01). Analysis of the mats by high performance liquid chromatography [HPLC] showed that the pigment fraction assayed spectrophotometrically as chlorophyll a contained large quantities (up to 70%) of the degradation product chlorophyllide a and the epimer chlorophyll a'. Photosynthetic rates per unit chlorophyll a[HPLC] were extremely slow: <0.1 mg C (mg Chla)−1, less than one tenth the rates recorded in the overlying phytoplankton community. These analyses indicate that in the ice pond benthic mats most of the dry weight is inorganic, most of the organic carbon is non-chlorophyll-containing material, and much of the chlorophyll a is not photosynthetically active. Cold temperatures and the associated low activity of herbivores and detritivores may contribute towards this preservation of inactive chlorophyll a on the McMurdo Ice Shelf, and perhaps in similar benthic mats in the lakes and streams of southern Victoria Land.

Hydrological measurements from three cruises during the summers 1994/95, 1995/96 and 1997/98 in the western sector of the Ross Sea allow summer and year to year changes in heat and salt content in the Terra Nova Bay polynya to be analysed. Changes in the surface layer (upper pycnocline) followed the expected seasonal pattern of warming and freshening from the beginning to the end of the summer. These near-surface changes, expressed as net heating and salting rate, were about 11 W m−2 and -6 mg salt m−2 s−1. The heating changes were substantially lower than the estimated heat supplied by the atmosphere during the summer, which underlines the importance for this season of the advective component carried by the currents in the total heat budget. The year to year differences were about one or two orders of magnitude smaller than the seasonal changes in the surface layer. In the intermediate and deep layers, the summer heat and salt variability were of the same order as or one order higher than from one summer to the next. The differences in sign and magnitude for the heat change in the upper and in the lower pycnocline indicate a weak connection in the summer period between the surface heat fluxes and the deep waters. A local source of very cold water (with temperatures below the surface freezing point) of about 0.3 Sv has been detected close to the Terra Nova Bay coast. It arose out of the interaction of the shallow–intermediate layers of High Salinity Shelf Water with the coastal glaciers. The presence and the variability of this cold water point to the significant role of the thermohaline properties of Terra Nova Bay waters in controlling the floating glacier by governing the basal melting processes.