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.

The diet and feeding behaviour of Illex argentinus were determined from analysis of stomach contents of squid caught during four bottom trawl surveys carried out over the Bonaerensis (34–40°S, autumn–winter 1991) and Patagonian (45–55°S, summer–autumn 1992) shelves of Argentina. Crustaceans, mainly Themisto gaudichaudii and, to a lesser extent, euphausiids were the most important components of the diet in both areas and years, although there were considerable geographical differences in the relative proportion of the main prey. In the Patagonian area, during summer and autumn of 1992, almost all squid preyed on crustaceans (percentage occurrence = 85.29%), followed by squid (11.76%) and fish (2.94%). On the Bonaerensis shelf, during autumn and winter of 1991, crustaceans were most important by percentage occurrence (56.96%), but fish and squid accounted for a large proportion of the diet (29.41% and 13.62% respectively). Myctophids were prevalent among the fish and cannibalism was on I. argentinus juveniles. Changes in diet composition with squid size demonstrated the opportunistic nature of I. argentinus feeding. Although large squids were able to catch large prey (fish, squid), they also fed on small crustaceans when available, especially in the Patagonian area. The relative abundance of different prey organisms probably determined the diet. In both areas and both years I. argentinus fed mostly during daylight hours, starting in the morning and reaching a maximum in the afternoon. No difference in feeding behaviour was observed between the sexes.

Sensitive High Resolution Ion MicroProbe (SHRIMP) U–Pb zircon dating of pegmatites from Mount Kirkby, northern Prince Charles Mountains, east Antarctica indicates felsic intrusive activity at 991 ± 22 Ma and 910 ± 18 Ma. Pegmatite emplacement occurred during prolonged high-grade early Neoproterozoic tectonism. These ages correlate well with previously published U–Pb zircon ages obtained from felsic intrusive bodies elsewhere within the northern Prince Charles Mountains. Early Palaeozoic activity at Mount Kirkby is restricted to the emplacement of minor planar pegmatites at 517 ± 12 Ma, which provide a maximum age for local development of discrete extensional mylonites. No conclusive evidence of tectonic or metamorphic events at c. 800 Ma and c. 500 Ma, which have been recently postulated for the region, can be identified from the presently available U–Pb zircon data.

A study of early winter first-year sea ice conditions and development in the western Ross Sea in May and June 1995 included measurements of snow and ice thickness, freeboard, ice core structure and stable isotopic composition. These variables showed strong spatial variability between the Ross Ice Shelf and the ice edge 1400 km to the north, and indicate that the development of the Ross Sea pack ice is quite different from that observed in other Antarctic sea ice zones. The thinnest snow and ice occurred in a 200 km wide coastal zone. The thickest snow and ice were observed in a continental shelf zone 200–600 km from the coast where the average ice thickness (0.8 m) determined by drilling is as thick as first-year sea ice later in winter elsewhere in Antarctica. A zone of moderate snow and ice thickness occurred on the deep ocean from 600 km to the ice edge at 1400 km. Thermodynamic thickening of the ice in the inner pack ice, <800 km from the coast, was dominated by congelation ice growth, which occurred in a greater amount (65%) and in thicker layers (mean: 20 cm) than was observed in the outer pack ice >800 km from the coast (amount: 22%; mean layer thickness: 12 cm) and elsewhere in the Antarctic pack ice. The preponderance of congelation ice in the inner pack ice might be due to a low oceanic heat flux on the Ross Sea continental shelf, and a colder, less stormy environment which favours the more frequent and prolonged calm conditions necessary for significant congelation ice growth. In the outer pack ice, thermodynamic thickening occurred mainly by snow ice formation (mean layer thickness: 20 cm) while dynamic processes, i.e., rafting and ridging, caused the thickening of frazil ice and columnar ice (mean layer thickness: 14 cm and 12 cm respectively). A greater amount of snow ice (37%) occurred in the outer pack ice than in the inner pack ice (15%), and both values indicate that in the Ross Sea, unlike other Antarctic sea ice zones, there can be significant seawater flooding of the snow/ice interface and snow ice formation before midwinter.

Predicting the effects of climate change on Antarctic terrestrial vegetation requires a better knowledge of the ecophysiology of common moss species. In this paper we provide a comprehensive matrix for photosynthesis and major environmental parameters for three dominant Antarctic moss species (Bryum subrotundifolium, B. pseudotriquetrum and Ceratodon purpureus). Using locations in southern Victoria Land, (Granite Harbour, 77°S) and northern Victoria Land (Cape Hallett, 72°S) we determined the responses of net photosynthesis and dark respiration to thallus water content, thallus temperature, photosynthetic photon flux densities and CO2 concentration over several summer seasons. The studies also included microclimate recordings at all sites where the research was carried out in field laboratories. Plant temperature was influenced predominantly by the water regime at the site with dry mosses being warmer. Optimal temperatures for net photosynthesis were 13.7°C, 12.0°C and 6.6°C for B. subrotundifolium, B. pseudotriquetrum and C. purpureus, respectively and fall within the known range for Antarctic mosses. Maximal net photosynthesis at 10°C ranked as B. subrotundifolium > B. pseudotriquetrum > C. purpureus. Net photosynthesis was strongly depressed at subzero temperatures but was substantial at 0°C. Net photosynthesis of the mosses was not saturated by light at optimal water content and thallus temperature. Response of net photosynthesis to increase in water content was as expected for mosses although B. subrotundifolium showed a large depression (60%) at the highest hydrations. Net photosynthesis of both B. subrotundifolium and B. pseudotriquetrum showed a large response to increase in CO2 concentration and this rose with increase in temperature; saturation was not reached for B. pseudotriquetrum at 20°C. There was a high level of variability for species at the same sites in different years and between different locations. This was substantial enough to make prediction of the effects of climate change very difficult at the moment.

Two massive tabular icebergs calved from the Ross Ice Shelf in 2000 (B-15) and 2002 (C-19) and perturbed regional ocean processes for several years. Here we document the ocean's response in McMurdo Sound to the icebergs using in situ data collected before, during and after the icebergs’ residence in the Ross Sea. Departures from typical McMurdo Sound seasonal oceanography included the non-appearance of Antarctic Surface Water in summer, a cooler and more homogeneous water column during winter and ‘super-fresh’ High Salinity Shelf Water that gradually recovered its salinity. We found that each iceberg triggered a distinct response to regional ocean processes. B-15a, the largest piece of iceberg B-15, restricted surface circulation, cooled and freshened the upper water column and reduced melting near the ice shelf front for four years. Iceberg C-19 interrupted the operation of the Ross Sea polynya, from which McMurdo Sound took three to four years to recover, and was responsible for a geographic shift in the dense water formation region for the south-western Ross Sea. These results differ from earlier modelling studies and highlight the challenges of modelling the polar ocean. We also show that one pathway previously thought to supply dense water to the Ross Ice Shelf cavity was not operating at that time.

The Larsemann Hills is an ice-free area of over 150 lakes that are not ice covered in summer. Despite being located at 69°30'S the area is not characterized to any extent by expected glacial indicators such as till, moraine or striations. Although the lakes show signs of evaporative lowering of water levels evolution to a saline state has not advanced to any great degree. While some evidence has been advanced to suggest only recent deglaciation (less than 10000yrBP) and large accumulations of ice (200–500m) it is now suggested that the area has not been glaciated during the Wisconsin to the extent previously claimed. The paper reports moss deposits aged 24950 yrBP that are significantly older than those previously reported for the area.

The lipid composition of microalgal communities dominated by diatoms collected from the sea ice at three locations within McMurdo Sound during the austral spring bloom of 1989/90, was determined using gas chromatography (GC) and GC mass spectrometry. A range of C27-C29 sterols were detected. The major sterols found at the three sites were 24-methylcholesta-5, 22E-diene-3β-ol (Cape Armitage); trans-22-dehydrocholesterol, 24-ethylcholesterol and 24-methylenecholesta (Erebus Ice Tongue); and 24-methylenecholesterol (Cape Royds). The difference in sterol profiles is believed to reflect the differing species composition at each site. The high relative levels (as % of total) of 24-ethylcholesterol at the Erebus Ice Tongue site (possibly related to Amphiprora kufferathii) supports the proposal that diatoms are a more probable source of C29 sterols in Antarctic lakes than are other algal groups or cyanobacteria. Changes in sterol composition over the course of the bloom were evident at the Cape Armitage site, particularly within the cellular free-lipid fraction. The major fatty acids identified were 14:0, 16:0, 16:1ω7c, 16:4ω1 and 20:5ω3 (Cape Armitage and Erebus Ice tongue sites); 16:0, 16:1ω7c and 20:5ω3 (Cape Royds site). All sites demonstrated high levels of PUFA (40–50% of total fatty acids), with an average 20:5ω3 level of 21% Erebus Ice Tongue, 20% Cape Royds, and 17% Cape Armitage. Variation was also observed in the percentage of 20:5ω3 for the Cape Armitage community over the sampling period. Levels of 22:6ω3 were between 0.4 and 1% of total fatty acids for the three sites. A C25:2 isoprenoid hydrocarbon was present in samples from all sites, adding further evidence to the proposal that diatoms are probably a source of this and related isoprenoid alkenes in marine and coastal sediments.

No information is available on the embryonic development of Southern Ocean cephalopods. Estimations of developmental times can only be made by extrapolation using data from other geographical areas. Based on known relationships between environmental temperature and embryonic development time, it appears that below 5°C even the smallest squid eggs measuring 0.6–1.0 mm in diameter need one to two months to develop to hatching. At c. 2°C, the embryonic development of these small eggs would probably cover between three and five months. Very large octopod eggs are known to develop over time spans of at least one year. Protection of the developing embryos either by long-lasting capsules laid at appropriate spawning sites, or by active ‘brooding’ (incirrate octopods) is required for embryonic survival and hatching success. The physiological conditions controlling the onset of hatching at very low temperatures are unknown; postponement of hatching appears to be common in cold waters.

In their upper layers, the polar ice sheets contain a detailed record of changes in the atmosphere over the industrial period. Measurements from air bubbles in ice have shown that the CO2 content of the atmosphere has increased by 25% in the last 200 years, and that of CH4 has more than doubled. Ice core records have demonstrated a close correspondence between greenhouse gases and temperature during the last glacial cycle. Profiles of radioactive species in snow clearly document nuclear bomb tests in the atmosphere, and the recent Chernobyl accident has also left a signal in Northern Hemisphere ice. Nitrate has more than doubled in Greenland snow over the industrial period, while sulphate has more than trebled. No significant trend is seen in Antarctic snow for these anions. Pb increased 100-fold until the 1970s in Greenland snow, but concentrations appear now to be declining. A small increase is also recorded in Antarctic snow. Organochlorine compounds offer great potential for pollution studies in snow. The ability to study global scale pollution in polar ice could be hampered if there is significant local pollution. In Antarctica, impact on the atmosphere from local human activities is still mainly confined to small areas near stations.

We present the first study from the Bransfield Basin that extends through the Holocene, recording the variable climate history back to the decoupling of the ice sheet from the continental shelf ~10 650 calendar years before present (cal yr bp). Detailed sediment analysis reveals three stratigraphic units in PC-61 concomitant with three sedimentary environments, similar to sedimentary facies reported elsewhere: 1) subglacial, 2) glacial proximal/sub-ice shelf, and 3) open marine. These interpretations are based on a variety of sedimentological criteria, supported by ten AMS radiocarbon dates and detailed diatom analysis. We note two significant volcanic ash layers (tephra) at 3870 and 5500 cal yr bp from nearby Deception Island. Based on diatom assemblage analysis, we identify five separate climate regimes, highlighting a significantly shorter Mid-Holocene Climatic Optimum than reported by other studies (6800–5900 cal yr bp). This period is marked by the highest Eucampia antarctica var. antarctica and Fragilariopsis curta abundance, total diatom abundance, sediment accumulation rates, and low magnetic susceptibility. We also identify a less pronounced Neoglacial period relative to other studies, which includes an increase of Cocconeis/Rhizosolenia spp. assemblage related to unstable surface water conditions. Such observations probably reflect important regional variations in atmospheric or ocean circulation patterns.

The non-long terminal repeat retrotransposons Rex1 and Rex3 were identified in 13 species of Antarctic fishes from five families of the suborder Notothenioidei. Partial reverse transcriptase gene sequences were characterized for Notothenia coriiceps, Trematomus newnesi and Dissostichus mawsoni (Nototheniidae), and Gymnodraco acuticeps (Bathydraconidae). Rex1 and Rex3 both formed a notothenioid-specific monophyletic group compared to the corresponding elements from other fishes. They globally evolved under purifying selection, showing their activity during notothenioid evolution. Fluorescence in situ hybridization analysis of the chromosomal distribution of Rex1 and Rex3 was performed for several notothenioid fish species. Rex1 was generally less abundant than Rex3, which was widely scattered on the chromosomes with more intense hybridization patterns in some specific zones. Particularly, Rex3 accumulated in Chionodraco hamatus in pericentromeric areas, short arms of some pairs as well as in an intercalary band in the long arm of the Y chromosome similarly to a previously described DNA transposon. Such pattern similarities suggest the presence of autosomal and gonosomal regions of preferential accumulation for different types of repeated elements in notothenioid genomes. To the best of our knowledge, this report is the first description and analysis of retrotransposable elements in Antarctic fish genomes.

In a study designed to elucidate the factors that might differentially affect the well being and biology of Adélie penguins (Pygoscelis adeliae) that breed in colonies of different size, we investigated the predation rates on penguins by leopard seals (Hydrurga leptonyx) over a period of six years. The study colonies varied in size across the full range for this penguin species, contrasting with previous studies in which data were gathered only at very large colonies, and only in single years. The number of seals present varied directly with the amount of penguin traffic in the areas near the beach, where most predation takes place. Seals were present persistently only when penguin traffic exceeded about 250 penguins per hour. Predation rates also varied with penguin traffic in a curvilinear fashion, leveling off where traffic exceeded about 1200 penguins per hour. With respect to predation, it appears to be advantageous for Adélie penguins to nest in very small or very large colonies. At large colonies, the number of penguins moving to and from the colony ‘swamp’ the seals' predatory efforts, thus reducing the chances that an individual penguin will be taken. Small colonies are of little interest to the seals.

Downward fluxes of particulate matter were investigated in the polynya of Terra Nova Bay (western Ross Sea) from February 1995 to December 1997. The main biological components were siliceous phytoplankton (diatoms, silicoflagellates and parmales), abundant faecal pellets of several types and zooplankton (mainly shelled pteropods). Vertical fluxes of particles occurred mainly through diatoms and faecal pellets in the first and second part of the summer, respectively. The highest fluxes were recurrently observed in late summer, when faeces contributed up to 100% of organic carbon. Unusually high fluxes were recorded in winter 1995, when faecal pellets accounted for 84.6% of the organic carbon. Peak fluxes were always driven by the sinking of faecal pellets, that hence appear to be the most efficient vector of export in the polynya of Terra Nova Bay. A major flux component was the pteropod Limacina helicina, which repeatedly sank in high amounts after the growing season. In April–June, L. helicina probably transported biogenic carbon to deep layers as a passive sinker. The inclusion of pteropods in flux estimates resulted in values that were up to 20 (for total mass), 25 (for organic matter) and 48 (for carbonate) times higher than the previously measured fluxes. Fluxes are known to be biased by swimmers, but ultimately attention must be paid to a possible erroneous categorization of some zooplankton as swimmers to avoid severe underestimation of fluxes of total mass (up to 95% in our study), organic matter (up to 96%) and carbonate (up to 100%).

Seasonal movements and foraging areas of postbreeding (n = 9) and postmoulting (n = 3) adult southern elephant seal females from Marion Island were studied using Geolocation Time-depth Recorders. Movements were classified into three phases – an outbound transit phase, distant foraging phase, and an inbound transit phase. The longest residence time of postbreeding females during their foraging migrations was in areas at the outer edge of their feeding range (± 1460 km) both to the north and south of the island, largely within inter-frontal zones south of the Antarctic Polar Front (APF) and between the Sub-Tropical Convergence (STC) and the Sub-Antarctic Front (SAF). Postmoulting females travelled further afield (2122–3133 km distant) to the APF, to inter-frontal zones south of the APF (within the pack ice outer edge), as well as to the Antarctic Continental Shelf. This study provides additional information on the putative function of dive types in relation to the movement phases of elephant seal females from Marion Island. The relative frequency of assumed ‘foraging’, ‘exploratory’ and ‘transit’ dive types, as well as the duration and location of the different phases of movement suggest two seasonal foraging strategies. Sea floor topography could possibly cue the transit phases of both postbreeding and postmoulting females from Marion Island.

Dense coral-sponge communities on the upper continental slope at 570–950 m off George V Land, East Antarctica have been identified as Vulnerable Marine Ecosystems. The challenge is now to understand their probable distribution on other parts of the Antarctic margin. We propose three main factors governing their distribution on the George V margin: 1) their depth in relation to iceberg scouring, 2) the flow of organic-rich bottom waters, and 3) their location at the head of shelf cutting canyons. Icebergs scour to 500 m in this region and the lack of such disturbance is a probable factor allowing the growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons which receive descending plumes of Antarctic Bottom Water formed on the George V shelf, which could entrain abundant food for the benthos. The canyons harbouring rich benthos are also those that cut the shelf break. Such canyons are known sites of high productivity in other areas due to strong current flow and increased mixing with shelf waters, and the abrupt, complex topography. These proposed mechanisms provide a framework for the identification of areas where there is a higher likelihood of encountering these Vulnerable Marine Ecosystems.

Geolocating-time-depth-temperature-recorders (GLTDTR) provided a continuous record of diving behaviour in relation to water temperature for ten female southern elephant seals from Macquarie Island during their post-breeding trips to sea. Four water bodies were determined from depth/temperature profiles recorded by the GLTDTRs. These water bodies corresponded to Sub-Antarctic Mode Water (SAMW), Polar Front Zone Water (PFZW), Polar Front Water (PFW) and Antarctic Water Masses (AWM). Thermal structures within these water bodies did not influence seal diving behaviour. Overall mean dive depth, nocturnal dive depths, diurnal dive depths and dive duration were similar in all areas. However, individuals did change behaviour as they moved between different water bodies. Seals also used different water bodies in the two different years of the study. We suggest that variations in foraging behaviour among seals are a result of prey distribution associated with local oceanographic conditions, but also reflect important individual foraging strategies within thermal zones.

In Antarctica, mass accumulations of psychrophilic algae cause striking phenomena like green, orange, or red snow. This occurs during summer, when coastal snowfields start to melt, become waterlogged and photoautotrophs can thrive. Chloromonas polyptera (Fritsch) Hoham, Mullet & Roemer is a unicellular species that causes orange snow in the vicinity of penguin rockeries. It has been recognized for many decades because of the distinct habitat and the characteristic morphology of cysts with elongated flanges on the outer cell wall. However, closer investigations concerning the ecology or physiology have been sparse so far. Field material was collected from two sites on the Antarctic Peninsula to find out more about metabolic and cellular strategies. The results were compared with a closely related species from high alpine locations, Chloromonas nivalis (Chodat) Hoham & Mullet. Despite the geographical distance, C. polyptera shares several physiological strategies with the alpine relative, such as the formation of cyst stages, saccharose and glycerol as main soluble carbohydrates and the abundant accumulation of the carotenoid astaxanthin. Moreover, photosynthesis is adapted to temperatures of about 1°C. The molecular phylogeny confirmed a close relationship of C. polyptera to other Chloromonas species isolated from snow. Chloromonas polyptera seems to be exclusive to coastal Antarctic ecosystems influenced by animal nutrient input.

Dry permafrost on Earth is unique to the Antarctic and is found in the upper elevations of the McMurdo Dry Valleys. Despite its widespread presence in the Dry Valleys, the factors that control the distribution of dry permafrost and the ice-cemented ground below it are poorly understood. Here I show, by a combination of theoretical analysis and field observations, that the recurrence of snow can explain the depth of dry permafrost and the location of ice-cemented ground in Antarctica. For data from Linnaeus Terrace at 1600–1650 m elevation in Upper Wright Valley a recurrence intervals of about two years explains the presence of ground ice at 25 cm depth, under 12.5 cm of dry permafrost. Snow recurrence periods longer than 10 years would create only dry permafrost at this site. The snow gradient in University Valley resulting from the windblown snow from the polar plateau creates a corresponding gradient in the depth to ice-cemented ground. On the floor of Beacon Valley, the presence of dry permafrost without underlying ice-cemented ground indicates snow recurrence intervals of more than 10 years and implies that the ancient massive ice in this valley is not stable. Snow recurrence may also set the depth to ground ice on Mars.