Wind and temperature profiles in the lowest 2000 m of the atmosphere at Halley (75°35′S, 26°50′W) have been analysed. Surface winds blow most frequently from the sector 090° ± 45° but the 2000 m wind direction is much more evenly distributed and appears to be determined by synoptic-scale pressure gradients. A simple one-dimensional boundary layer model, which includes the effects of stably-stratified air overlying a sloping surface, is able to reproduce some of the features of the observed profiles.

Available literature data on age and growth of high Antarctic fish is reviewed and discussed in relation to environmental seasonality. Except for Antarctic toothfish Dissostichus mawsoni, with maximum total length (TL) more than 170 cm, high Antarctic notothenioids are predominantly small species of less than 45 cm TL. Maximum ages reported for small Trematomus species were generally high (18–23 years), and probably comparable to those of some larger channichthyids. Highest longevity is attained by large nototheniids, such as Aethotaxis mitopteryx and D. mawsoni, of more than 30 years. Most high Antarctic fish spawn for the first time at 50–80% of maximum age. Males of some Trematomus species reach spawning maturity earlier than females, but at a higher percentage of maximum age. Pauly's index of growth performance P has been used to compare growth. P for nototheniids is typically between 1 and 2, whereas in channichthyids it is between 2 and 3. Generally, high Antarctic notothenioids exhibit a lower P than those further north. In high Antarctic nototheniids, between 19 and 42 cm maximum theoretical length, growth performance seems to increase from pelagic to benthic fish habit. Thus, although low temperature is a constraint on growth, other ecological factors linked to life style, such as food availability and physiological adaptations, may explain differences in growth performance between fish from the seasonal pack-ice zone and the high Antarctic zone.

Seventy-three sponge species were caught at 23 stations on the continental shelf of the Lazarev and Weddell Sea (Atlantic sector of the Southern Ocean). Tedania tantula was the most often found species amongst the 63 demosponge species caught and among the five hexactinellid species Rossella racovitzae was most common. The stations were classified according to their species inventory, and so the individual stations of the resulting four groups were rather uniformly dispersed over the entire investigation area. The species composition of adjacent stations varied considerably. There was no discernible relationship between the biological set of data and any combination of the available environmental characteristics of the stations. The sponge fauna of the, so far very poorly investigated, Lazarev Sea did not differ considerably from that of the adjacent Weddell Sea. The only species to be recorded for the first time on the Antarctic continental shelf were Homaxinella flagelliformis and Hyrtios arenosa. Small scale environmental events such as iceberg scouring, or biological characteristics such as extremely slow growth and budding reproduction are thought to generate the patchy distribution pattern.

The internal structure of ice cores from western Ross Sea pack ice floes showed considerable diversity. Snow-ice formation made a small, but significant contribution to ice growth. Frazil ice was common and its growth clearly occurred during both the pancake cycle and deformation events. Congelation ice was also common, in both its crystallographically aligned and non-aligned varieties. Platelet ice was found in only one core next to the Drygalski Ice Tongue, an observation adding to the increasing evidence that this unusual ice type occurs primarily in coastal pack ice near ice tongues and ice shelves. The diverse internal structure of the floes indicates that sea ice development in the Ross Sea is as complex as that in the Weddell Sea and more complex than in the Arctic. The mean ice thickness at the ice core sites varied between 0.71 m and 1.52 m. The thinnest ice generally occurred in the outer pack ice zone. Regardless of latitude, the ice thickness data are further evidence that Antarctic sea ice is thinner than Arctic sea ice.

There are marked declines in precipitation, mean temperatures and the number of lichen species with increasing latitude in Antarctica. However, it is not known which factors are the predominant controllers of biodiversity changes. Results are presented from over two years of almost continuous monitoring of both microclimate and activity in lichens at Livingston Island, South Shetland Islands, 62°S, and Botany Bay, Ross Sea region, 77°S. Lichen activity was evident over a much longer period at Livingston Island, (3694 versus 897 hours) and could occur in any month whereas it was almost completely confined to the period November–February at Botany Bay. Mean air temperatures were much lower at Botany Bay (-18° compared to -1.5°C at Livingston Island), but the temperatures at which the lichens were active were almost identical at around 2°C at both sites. When the lichens were active incident light at Botany Bay was very much higher. The differences are related to the availability of meltwater which only occurs at times of high light and warm temperatures at Botany Bay. Temperature as a direct effect does not seem to explain the differences in biodiversity between the sites, but an indirect effect through active hours is much more probable. In addition there are negative effects of stresses such as high light and extreme winter cold at Botany Bay.

The white-chinned petrel (Procellaria aequinoctialis) is an abundant, widespread petrel breeding in tussock grassland at sub-Antarctic islands. Over the last decade it has been killed in large numbers in temperate and sub-tropical longline fisheries. However no data are available on the global population status. We assessed the status of white-chinned petrels at Bird Island, South Georgia by comparing the distribution and density of occupied burrows in 1981 and 1998. In both surveys white-chinned petrel burrows occurred in one-quarter of the 460–477 36-m2 quadrats surveyed. The total number of burrows in each quadrat was consistent between each survey but we estimate an overall decrease of 28% in those occupied (with considerable variation between sites). Concurrent data on breeding frequency and success showed that white-chinned petrels are essentially annual breeders at Bird Island; breeding success was consistent at around 44%. Significant factors determining densities of occupied burrows were crown height and percent tussock cover (accounting for 77% of variance). The former has decreased significantly, the latter increased significantly between 1981 and 1998 but there was no relationship between white-chinned petrel occupancy rate and habitat modification due to the presence of fur seals (Arctocephalus gazella). This suggests that any population decline is due to factors operating away from the breeding colony, such as those attributed to fishing.

Diverse microbial communities survive within the sea ice matrix and are integral to the energy base of the Southern Ocean. Here we describe initial findings of a four season survey (between 1999–2004) of community structure and biomass of microalgae within the sea ice and in the underlying water column at Cape Evans and Cape Hallett, in the Ross Sea, Antarctica as part of the Latitudinal Gradient Project. At Cape Evans, bottom-ice chlorophyll a levels ranged from 4.4 to 173 mg Chl a m−2. Dominant species were Nitzschia stellata, N. lecointei, and Entomoneis kjellmanii, while the proportion of Berkeleya adeliensis increased steadily during spring. Despite being obtained later in the season, the Cape Hallett data show considerably lower standing stocks of chlorophyll ranging from 0.11 to 36.8 mg Chl a m−2. This difference was attributed to a strong current, which may have ablated much of the bottom ice biomass and provided biomass to the water below. This loss of algae from the bottom of the ice may explain why the ice community contributed only 2% of the standing stock in the total water column. Dominant species at Cape Hallett were Nitzschia stellata, Fragilariopsis curta and Cylindrotheca closterium. The low biomass at Cape Hallett and the prevalence of smaller-celled diatoms in the bottom ice community indicate that the ice here is more typical of pack ice than fast ice. Further data will allow us to quantify and model the extent to which ice-driven dynamics control the structure and function of the sea ice ecosystem and to assess its resilience to changing sea ice conditions.

The emperor penguin (Aptenodytes forsteri) is highly dependent on sea ice conditions, and future climate change may affect its distribution and numbers. Most studies on the demography and population dynamics of emperor penguins in relation to sea ice characteristics were conducted at a single colony (Pointe Géologie). Several non-exclusive hypotheses have been proposed to explain the dramatic decline of this colony, including changes in sea ice conditions, predation, flipper banding and human disturbance. Here, we report and analyse updated long-term trends in numbers of breeding pairs made at two colonies (Pointe Géologie and Haswell Island) where counts are comparable. Similar changes were observed for both colonies and paralleled changes in sea ice extent. At Pointe Géologie and Haswell Island, populations declined similarly and later growth rates were also similar since the early 1990s for Haswell and early 1980s for Pointe Géologie. The magnitude of the decline was similar between both colonies when numbers of breeding pairs were assessed. This study suggests that a common large-scale environmental factor has probably negatively affected both colonies.

Information on Holocene glacier variations in Antarctica is limited and sometimes contradictory. However, if the behaviour of the glaciers during the recent past can be clarified, their sensitivity to climatic changes can be evaluated and their contribution to the sea level variation may be predicted. Through the study of local glaciers and floating ice shelves in the Terra Nova Bay area, new information has been gathered. Between 7500 and 5000 yr B.P., after the glacial retreat which followed the Last Glacial Maximum, the Nansen Ice Sheet and the Hells Gate ice shelf were a few kilometres less extensive than they are now. During the second half of the Holocene, both the local glaciers and the ice shelves advanced to positions that were more extensive than their present ones, although not all the variations are adequately dated. A retreat phase of the Edmonson Point glacier occurred during late Middle Ages between 920–1050 A.D. and 1270–1400 A.D. as documented by ten 14C dates obtained from shells in ice-cored moraines. A subsequent advance occurred after the 15th century in a period corresponding to the Little Ice Age.

Swimming activity of the Antarctic scallop at a temperature of c. −1.4°C was analysed using in situ video recordings obtained from a remotely operated vehicle (ROV) in Terra Nova Bay, Ross Sea. Data are presented on swimming trajectories, distance travelled and velocity during a swimming bout, adduction frequency, shell gape angle, and the angular opening and closing velocities of shell. This scallop is an effective swimmer although swimming bouts in response to the ROV were generally short, consisting of 2–5 adduction cycles in the take-off phase followed by 1–4 (exceptionally 14) adductions during level swimming. The maximum velocity during each adduction cycle ranged from 19.4–43.1 cm s−1 and the mean velocity during a swimming bout from 12.0–23.5 cm s−1. Each adduction cycle consists of opening, closing and glide phases of approximately equal duration. Adduction frequency during swimming averaged 1.5 adductions s−1.

The continental margin of Gondwana preserves a record of long-lived magmatism from the Andean Cordillera to Australia. The crustal blocks of West Antarctica form part of this margin, with Palaeozoic–Mesozoic magmatism particularly well preserved in the Antarctic Peninsula and Marie Byrd Land. Magmatic events on the intervening Thurston Island crustal block are poorly defined, which has hindered accurate correlations along the margin. Six samples are dated here using U-Pb geochronology and cover the geological history on Thurston Island. The basement gneisses from Morgan Inlet have a protolith age of 349±2 Ma and correlate closely with the Devonian–Carboniferous magmatism of Marie Byrd Land and New Zealand. Triassic (240–220 Ma) magmatism is identified at two sites on Thurston Island, with Hf isotopes indicating magma extraction from Mesoproterozoic-age lower crust. Several sites on Thurston Island preserve rhyolitic tuffs that have been dated at 182 Ma and are likely to correlate with the successions in the Antarctic Peninsula, particularly given the pre-break-up position of the Thurston Island crustal block. Silicic volcanism was widespread in Patagonia and the Antarctic Peninsula at ~ 183 Ma forming the extensive Chon Aike Province. The most extensive episode of magmatism along the active margin took place during the mid-Cretaceous. This Cordillera ‘flare-up’ event of the Gondwana margin is also developed on Thurston Island with granitoid magmatism dated in the interval 110–100 Ma.

The question of how stable the climate in Antarctica has been during the last few million years compared to the rest of the planet is still controversial. This study attempts to add new information to the discussion by reconstructing the timing and spatial extent of glacial advances in northern Victoria Land over tens of thousands to millions of years. In Terra Nova Bay region, surface exposure ages and erosion rates of glacially rounded bedrock and glacial erratics have been determined using the cosmogenic nuclides 3He, 10Be and 21Ne. Three morphological units have been analysed. They yield minimum ages of 11 to 34 ka, 309 ka, and 2.6 Ma, respectively. Erosion rates were as low as 20 cm Ma−1 since middle Pliocene time. Taking erosion into account, the oldest surface is 5.3 Ma old. Pleistocene glacier advances had considerable extent, reaching up to 780 m above modern ice levels, but have been restricted to the valleys since at least mid-Pliocene. The existence of landscapes of mid-Pliocene age in northern Victoria Land implies that the climatic stability of the McMurdo Dry Valleys is not unique within the Transantarctic Mountains, but rather the expression of a constantly cold and hyperarid climate regime in entire Victoria Land.

A surface energy balance model is forced by 13 years of high-quality hourly observations from the Antarctic coastal station Neumayer. The model accurately reproduces observed surface temperatures. Surface sublimation is significant in summer, when absorbed solar radiation heats the surface. Including a first order estimate of snowdrift sublimation in the calculation more than triples the total sublimation, removing 19% of the solid precipitation, indicating that snowdrift sublimation is potentially important for the mass balance of Antarctic ice shelves. Surface melt occurs at Neumayer in all summers, but all the meltwater refreezes. In two-thirds of the cases, the refreezing is quasi-instantaneous (within the model timestep of 6 min), so that no liquid water remains in the snow. For all other events, the occurrence of liquid water in the snowpack at Neumayer agrees well with satellite-based liquid water detection.

A new fauna of late Early to early Middle Triassic vertebrates has been found in the upper member of the Fremouw Formation in the Beardmore Glacier area of Antarctica. It includes Cynognathus, a kannmeyeriid, and other therapsid (mammal-like) reptiles representing new, more derived genera of carnivorous and gomphodont cynodonts. New genera of temnospondyl amphibians belonging to the capitosauroid evolutionary complex also occur. The unusual abundance of well-preserved amphibians may offer new insights concerning the evolution and distribution patterns of early Mesozoic temnospondyls. These fossils represent only the second terrestrial vertebrate fauna from the mainland of Antarctica. The fossils occur on a prominent sandstone platform, which represents part of the exhumed channel of a braided stream deposit. The platform is over 200 metres above the well-known Lystrosaurus fauna of the lower Fremouw Formation. The locality is near the axis of a major foreland basin that paralleled the present trend of the Transantarctic Mountains. Conditions of rapid subsidence and aggradation of fluvial units were ideal for the preservation of vertebrate faunas.

The biology and ecology of Cephaloziella varians, the most widespread and abundant liverwort in Antarctica, are reviewed. A description of the species is given, together with information on its geographical distribution, reproduction, habitats, associated organisms and responses to environmental stresses. Characteristics of its photosynthetic physiology are also presented, including data on oxygen evolution rates and chlorophyll a fluorescence parameters. Substratum and tissue chemistry, water relations and pigments are discussed, along with recent data demonstrating that the dark pigment in the apical leaves of C. varians is the anthocyanidin riccionidin A. Recent studies showing that the ericoid mycorrhizal symbiont Rhizoscyphus ericae is present in the tissues of the plant at a wide range of locations in the maritime and sub-Antarctic are also described. It is evident, from the literature reviewed, that C. varians has several adaptations that enable it to survive in the Antarctic biome, explaining its survival at higher latitudes than any other hepatic. The species’ major adaptations include the synthesis of riccionidin A in apical leaves, enabling efficient heat absorption and protection from photoinhibition, and the presence in stems and rhizoids of fungal hyphae, which are potentially beneficial to the hepatic’s nutrition and possibly also synthesize cryoprotectants.

Here we describe the evolution through winter of a layer of in situ supercooled water beneath the sea ice at a site close to the McMurdo Ice Shelf. From early winter (May), the temperature of the upper water column was below its surface freezing point, implying contact with an ice shelf at depth. By late winter the supercooled layer was c. 40 m deep with a maximum supercooling of c. 25 mK located 1–2 m below the sea ice-water interface. Transitory in situ supercooling events were also observed, one lasting c. 17 hours and reaching a depth of 70 m. In spite of these very low temperatures the isotopic composition of the water was relatively heavy, suggesting little glacial melt. Further, the water's temperature-salinity signature indicates contributions to water mass properties from High Salinity Shelf Water produced in areas of high sea ice production to the north of McMurdo Sound. Our measurements imply the existence of a heat sink beneath the supercooled layer that extracts heat from the ocean to thicken and cool this layer and contributes to the thickness of the sea ice cover. This sink is linked to the circulation pattern of the McMurdo Sound.

The central and western Transantarctic Mountains appear to be divided longitudinally by one or more terrane boundaries that separate two regions characterized by different Lower Palaeozoic successions. Re-examination of the upper Beardmore Glacier area and reinterpretation of its Early Palaeozoic stratigraphy emphasizes the strong similarity between it and the Byrd Group outcrops in the area between the Byrd and Nimrod glaciers. This similarity demonstrates that for several hundred kilometres the Cambrian succession of an inboard region is largely devoid of volcanic rocks but includes fossiliferous Lower Cambrian platformal limestones that are overlain unconformably by coarse basin-fill deposits. The latter probably include beds of Middle and perhaps early Late Cambrian age that were themselves deformed prior to the Devonian. Erratic blocks indicate that comparable successions may have been developed as far west as the Whichaway Nunataks. The inferred geological history of this part of the continental margin, which is commonly regarded as autochthonous, stands in contrast to that of more outboard regions where thick volcanic sequences occur in expanded stratigraphic sections that include shallow-marine Middle and Late Cambrian deposits. We consider that these regions, predominantly the Queen Maud and Theil mountains and the Neptune Range of the Pensacola Mountains, constitute one or more displaced crustal blocks. The boundary between them and the inboard sequence adjacent to the craton is probably a series of large strike-slip faults that may have been initiated during the Early Palaeozoic and have been active episodically since then.

In the Weddell Sea oceanographic data and numerical models demonstrate that Ice Shelf Water, one ingredient in the production of Weddell Sea Bottom Water, is formed by thermohaline interaction of High Salinity Shelf Water with the base of the Filchner-Ronne ice shelves. South of Berkner Island a passage with a water column thickness of about 300 m linking the Filchner and the Ronne regimes is important for the ventilation of the sub-ice shelf cavities. To simulate the flow we tested a two-dimensional thermohaline circulation model on several sections which approximate different geometries of a sub-ice shelf channel bounded by the ocean bottom and the ice shelf base. Temperature and salinity profiles measured in front of the Filchner-Ronne ice shelves are used to force the model. The results indicate that the circulation is sensitive to both salinity (density) forcing and depth of the shelf bottom prescribed at the open boundary representing the Ronne Ice Shelf edge. Where the shelf is shallow, 400 m deep, a closed circulation cell within the Ronne cavity acts like an ice pump with accumulation rates of marine ice at the ice shelf base up to 1.5 m y−1. The total outflow at the Ronne Ice Shelf edge is supported by an inflow from the Filchner regime. Where the shelf is deeper, a flow from the Ronne into the Filchner cavity develops if the bottom salinity at the Ronne Ice Shelf edge exceeds a critical value of 34.67. Seasonal variability imposed at both edges modifies the circulation pattern at the Filchner Ice Shelf edge such that the depth and magnitude of Ice Shelf Water outflow correspond with observations in the Filchner Depression.

Energy transfer in microbial food webs is partly quantified by the relationship between bacterial and algal biomass. Tight spatial relationships suggest active bacterial assimilation of dissolved photosynthate in temperate marine and fresh waters. However, studies in the Antarctic suggest that bacterial biomass generation from algal-derived dissolved organic matter is highly variable across seasons and habitats. Regression analysis was used to measure how bacteria covaried with algae in sea ice and water column habitats at three sites around Antarctica. Bacteria and algae were positively related in sea ice of the Weddell Sea during early winter 1992 (r2 = 0.16, slope = 0.24) and across sea ice and upper water column habitats of the Ross Sea during summer 1999 (r2 = 0.52, slope = 0.50). Conversely, bacteria and algae exhibited no discernible relationship in the water column and first year ice habitats of the Western Antarctic Peninsula region in winter 2001 (r2 = 0.003, slope = −0.04). Low algal production and residual biomass probably limited bacterial production and facilitated bacteria-algae uncoupling in winter sea ice of the Western Antarctic Peninsula. Winter sea ice algal biomass was probably limited by a relatively late date of initial ice formation, reduced multi-year ice coverage, and a lack of radiant energy in the winter ice pack.