The predicted increase in liquid water availability in the McMurdo Dry Valleys (MDV), Antarctica, may have profound consequences for nutrient cycling in soil and aquatic ecosystems. Our ability to predict future changes relies on our understanding of current nutrient cycling processes. Multiple hypotheses exist to explain the variability in soil phosphorus content and availability found throughout the MDV region. We analysed 146 surface soil samples from the MDV to determine the relative importance of parent material, landscape age, soil chemistry and texture, and topography on two biologically relevant phosphorus pools, HCl- and NaHCO3-extractable phosphorus. While HCl-extractable phosphorus is highly predicted by parent material, NaHCO3-extractable phosphorus is unrelated to parent material but is significantly correlated with soil conductivity, soil texture and topography. Neither measure of soil phosphorus was related to landscape age across a gradient of ~20 000 to 1 500 000 years. Glacial history has played an important role in the availability of soil phosphorus by shaping patterns of soil texture and parent material. With a predicted increase in water availability, the rate of mineral weathering may increase, releasing more HCl-extractable phosphorus into soil and aquatic ecosystems.

Evolutionary disparate Antarctic notothenioids and Arctic gadids have adapted to their freezing environments through the elaboration of essentially identical antifreeze glycoproteins (AFGPs). Here we show that this convergence of molecular identity, which evolved from unrelated parent genes, extends to convergence in physiological deployment. Both fish groups synthesize AFGPs in the exocrine pancreas from where they are discharged into the gut to inhibit the growth of ingested ice. Antifreeze glycoproteins not lost with the faeces are resorbed from the gut via the rectal epithelium, transported to the blood and ultimately secreted into the bile, from where they re-enter the gastrointestinal tract. Antifreeze glycoprotein recirculation conserves energy expenditure and explains how high levels of AFGPs reach the blood in notothenioids since, unlike Arctic gadids which also synthesize AFGP in the liver, AFGP secretion in notothenioids is directed exclusively towards the gastrointestinal lumen. Since AFGPs function by inhibiting ice crystal growth, ice must be present for them to function. The two fish groups are thus faced with an identical problem of how to deal with internal ice. Here we show that both accumulate AFGPs within ellipsoidal macrophages of the spleen, presumably adsorbed to phagocytosed ice crystals which are then held until a warming event ensues.

This study presents the first subglacial topography and ice thickness models of the largest ice caps of the Argentine Islands, Wilhelm Archipelago, West Antarctica. During this study, ground-penetrating radar was used to map the thickness and inner structure of the ice caps. Digital surface models of all studied islands were created from aerial images obtained with a small-sized unmanned aerial vehicle and used for the construction of subglacial topography models. Ice caps of the Argentine Islands cover ~50% of the land surface of the islands on average. The maximum thickness of only two islands (Galindez and Skua) exceeds 30 m, while the average thickness of all islands is only ~5 m. The maximum ice thickness reaches 35.3 m on Galindez Island. The ice thickness and glacier distribution are mainly governed by prevailing wind direction from the north. This has created the prominent narrow ice ridges on Uruguay and Irizar islands, which are not supported by topographic obstacles, as well as the elongated shape of other ice caps. The subglacial topography of the ice caps is undulated and mainly dependent on the geological structure and composition of magmatic rocks.

Sea ice provides a habitat for a conspicuous and productive assemblage of autotrophic microalgae and for heterotrophs ranging from bacteria to vertebrates (Horner 1990, Garrison 1991). With the exception of a reference to chytridiaceous fungi that were found infecting Arctic ice diatoms (Horner 1977) and a note in a cruise report (Schnack-Schiel 1987, p. 153), it appears that fungi and similar organisms have until now not been mentioned as members of the heterotrophic sea ice community. In the present short note we report on the abundant occurrence of apparently thraustochytrid fungus-like protists associated with mucilage tubes of pennate diatoms, encountered in the lower section of a fast ice core drilled close to the southern shelf ice margin of the Weddell Sea.

Ground ice is one of the most important and dynamic geologic components of permafrost; however, few studies have investigated the distribution and origin of ground ice in the McMurdo Dry Valleys of Antarctica. In this study, ice-bearing permafrost cores were collected from 18 sites in University Valley, a small hanging glacial valley in the Quartermain Mountains. Ground ice was found to be ubiquitous in the upper 2 m of permafrost soils, with excess ice contents reaching 93%, but ground ice conditions were not homogeneous. Ground ice content was variable within polygons and along the valley floor, decreasing in the centres of polygons and increasing in the shoulders of polygons towards the mouth of the valley. Ground ice also had different origins: vapour deposition, freezing of partially evaporated snow meltwater and buried glacier ice. The variability in the distribution and origin of ground ice can be attributed to ground surface temperature and moisture conditions, which separate the valley into distinct zones. Ground ice of vapour-deposition origin was predominantly situated in perennially cryotic zones, whereas ground ice formed by the freezing of evaporated snow meltwater was predominantly found in seasonally non-cryotic zones.

The statolith microstructure was studied in 142 females (mantle length, ML, ranging from 77–402 mm) and 119 males (72–328 mm ML) of Martialia hyadesi caught on the Patagonian and Falkland shelves and at the Antarctic Polar Frontal Zone between 1989–94. The statolith microstructure dark zone in this species, contains narrower and more numerous growth increments than the dark zones of other ommastrephid squids. Assuming daily production of putative growth increments within statoliths males live up to 12 months, and females live up to 13 months. It is likely that the life cycle lasts c. 1 yr, but immature squids with ages >330–340 d suggest that a part of M. hyadesi populations could have life span >1 yr. Growth in length was best described by the Gompertz function, whereas growth in weight was best described by the logistic function. M. hyadesi is characterized by slow juvenile growth (<100 mm ML), fast growth of immature squids and a sharp decrease in growth rates during maturation. M. hyadesi mature later (at ages >270 d) than other temperate ommastrephids, but maturation is rather rapid (2–3 months). In the south-west Atlantic, M. hyadesi hatch throughout the year.

A hawaiite dyke dated at 3.88 ± 0.05 Ma from the Mount Morning eruptive centre intrudes a diamictite deposit at Gandalf Ridge in the southern Ross Sea. The dyke has been dextrally offset up to 6 m horizontally by faults interpreted as the onshore continuation of the West Antarctic rift system (WARS) fault array. Felsic dykes emplaced during the Miocene are also present at Gandalf Ridge. The offset of the Miocene dykes is equivalent to the offset on the hawaiite dyke, suggesting that at this locality movement on faults within WARS has been restricted to a period more recent than c. 3.88 Ma. Over this period the minimum average rate of movement on these faults within WARS is 0.0015 mm yr-1.

Precambrian continental extension is described in detail for the first time in the Victoria Land segment of the Transantarctic Mountains and is comparable with plume related intercontinental rifting of the Afar area, Africa. The Baronick Formation comprises igneous-derived conglomerate, marble and volcanic to sub-volcanic igneous layers. Volcanic and carbonate horizons were eroded in a fluvial or marine environment and provided debris for mass flow and slump deposits which formed in a marginal marine basin in the Precambrian. Clasts in these deposits include basalt, trachyte and comendite, and along with the interbedded volcanic layers of basalt, trachyte and quartz syenite, indicate proximity and contemporaneity of volcanic activity. Igneous layers and source rocks for clasts of the Baronick Formation have an enriched MORB chemistry and underwent albitization of calcic feldspar before erosion and conglomerate deposition. The Highway Suite forms a kilometre-scale body of gabbro and dolerite plugs and is interpreted as a slice of transitional continental oceanic crust. The chemistry of all igneous rocks suggests a continental rift environment and the associated sediments are consistent with such a setting. The Baronick Formation was locally intruded by sills of the Highway Suite; however, the main body of the Highway Suite was juxtaposed against the Baronick Formation during greenschist facies shearing before c. 551 Ma.

The endemic Antarctic scallop Adamussium colbecki (Mollusca: Bivalvia) represents a key species in the Ross Sea littoral benthic ecosystem, locally reaching very high densities. This species has an annual gametogenic cycle, with a summer spawning event, and a pelagic larval behaviour. This paper aims at describing population structure and genetic polymorphism (using AFLP) of the large populations inhabiting the Ross Sea (Terra Nova Bay and McMurdo Sound) in order to investigate possible genetic exchange between A. colbecki in these areas. In Terra Nova Bay, size-frequency distributions show, generally, the dominance of large individuals, although site related differences are found in the abundance of smaller size classes (less than 40 mm), suggesting that recruitment is not a regular event. All McMurdo sites are characterized by large individuals and, at least during this sampling period, recruitment is completely absent. Nuclear DNA analyses show that the largest differences are found at the largest scale (between McMurdo Sound and Terra Nova Bay), but all populations sampled, even at a smaller spatial scale, have a well-settled genetic structure, notwithstanding the pelagic larval strategy. The panmixia hypothesis has therefore to be rejected for this species.

High-resolution trends of nutrients and DOM are analysed, with respect to nitrate and ammonium uptakes, in two coastal stations placed on the annual land-fast ice at Terra Nova Bay. The highest accumulations of dissolved inorganic nitrogen (87.2 µmol N dm-3), reactive phosphorus (14.1 µmol P dm-3) and reactive silicon (22.9 µmol Si dm-3) were observed in the bottom ice, although this process was preceded by a nutrient decrease in an interior sea ice layer. In the upper layer of sea ice, DOM was rather constant in concentration and P-deficient (C:N:P = 377:34:1–579:53:1). In the bottom and platelet ice, the accumulation of DOM (1277 µmol C dm-3; 108.2 µmol N dm-3; 7.67 µmol P dm-3) occurred with lower C:N:P ratios (123:14:1–59:7:1), because of a major contribution of fresher organic matter. Nitrate (< 7.33 µmol N dm-3 d-1) and ammonium (< 2.85 µmol N dm-3 d-1) uptakes in the bottom ice were higher than in the platelet ice. The comparison between the data of N-uptake and the concomitant release of total dissolved nitrogen in the bottom ice indicated that the microbial community may be subjected to low growths in situ and high releases of dissolved nitrogen, when it accumulates in this sea ice habitat.

During a cruise to the Ross Ice Shelf we counted all penguins and marine mammals seen whilst underway. Our objective was to determine the abundance and distribution of these animals along our cruise line. From 14 May until 11 June the sun was below the horizon. Our observations were from the 18 m high bridge. Most watches were in the dark, aided by the bridge spotlights. A total of 79 emperor penguins, 920 Adélie penguins, and 27 marine mammals were counted. We conclude that the Ross Sea, in which wildlife flourishes during the summer, is depauperate in winter. The low numbers of marine mammals may be due partially to their tendency to remain below the surface most of the time. However, Adélie penguins, a visual hunter which rests on sea ice at night, appear to prefer pack ice edges where there is a few hours of daylight and civil twilight for pursuit of prey. Non-breeding emperor penguins also rest on sea ice at night. All but four were observed north of the Ross Sea. Unlike more northerly colonies where females lay their egg and disperse in May female departure in the Ross Sea appears to be later and, we were unable to determine their winter foraging area.

Antarctic marine invertebrates from the Western Antarctic Peninsula (WAP) are generally stenothermal, with three-month survival and activity limits above the average maximum summer seawater temperature (1.0°C) of 1–6°C and 1–3°C respectively. For many of these species to survive the warmer maximum temperature at the sub-Antarctic island of South Georgia (5°C), they require either greater thermal flexibility, or must avoid the warmest water-masses. The mean depths and depth range of WAP gastropod and bivalve molluscs were compared with the mean depths of these same species at South Georgia; separated into water masses delimited by the 1°C isotherm at South Georgia, surface Antarctic water (SAW < 90 m), winter water (WW 90–150 m) and circumpolar deep water (CDW > 150 m). Bivalves in the SAW and CDW categories at the WAP were centred around the cooler WW (< 1.2°C) at South Georgia, with a narrower mean depth range for CDW bivalves. There was no difference in the average depth of gastropods, but a reduced depth range in the CDW. The apparent temperature limit to bivalve mean depths and not gastropods at South Georgia, suggests that further latitudinal comparisons could yield information on the underlying physiological mechanisms determining the range limits of Southern Ocean fauna.

Macaroni penguins (Eudyptes chrysolophus) and rockhopper penguins (E. chrysocome) account for a substantial proportion of the avian biomass at the subantarctic Prince Edward Islands (47°S, 38°E) in summer, when both species are breeding at the islands. Information on breeding population sizes, breeding and moulting activities, and diets were combined with measurements of the penguins' energy expenditures to construct a bioenergetic model of their energy requirements and food consumption at the islands. Total energy requirements of adults and chicks amounted to 460 × 109 kJ and 162 × 109 kJ for macaroni and rockhopper penguins, respectively. Food consumption was estimated to amount to a total of 166 000 tonnes during the seven-month breeding and moulting cycle, of which macaroni penguins consumed 75%. Most, if not all, of this food is taken within a 200-km radius of the islands. Available information suggests that potential primary production in the immediate vicinity of the islands is sufficient to support the macaroni and rockhopper penguin populations. However, the importance in the diets of the penguins of several prey species more typical of Antarctic and subtropical regions suggests that the penguins rely to a large extent on the importation of prey populations from other areas.

A survey of nearshore areas in the Vestfold Hills, Antarctica, using high-resolution multibeam swath bathymetry provided both a detailed digital bathymetric model and information on sediment acoustic backscatter. Combined with underwater video transects and sediment sampling, these data were used to identify and map geomorphic units. Six geomorphic units identified in the survey region include: rocky outcrops, basins, pediments, valleys, scarps and embayments. In addition to geomorphic units, the data revealed sedimentary features that provide insights into post-glacial sediment transport and erosion in the area. Ice keel pits and scours are common, and sea floor channels, scour depressions and sand ribbons indicate transport and deposition by wind-driven currents and oceanographic circulation. Gullies and sediment lobes observed on steep slopes indicate mass movement of sediment. Some of these processes have not been directly observed to date, but their effectiveness in shaping the modern sea floor is clearly indicated by the sea floor mapping data. The embayments preserve a mantle of boulder sand probably deposited by cold-based glaciers which were flanked by faster-flowing ice in adjoining regions.

The biogeochemical cycle of lead in the marine coastal environment of Terra Nova Bay has been investigated by determining the lead concentration in a large number of matrices: marine sediments, pack ice, snow, seawater, marine microlayer, aerosol and eight species of marine organisms (the bivalve molluscs Adamussium colbecki and Laternula elliptica, the seastar Odontaster validus, the sea urchin Sterechinus neumayeri, the fish Trematomus bernacchii, the seaweeds Iridaea cordata and Phyllophora antarctica, and the nemertine worm Parborlasia corrugatus). The study of solid speciation of sediment showed that the site is not influenced by human activity and is hence suitable to examine natural processes. The concentration values found in the suspended paniculate matter (SPM) of pack ice core, aerosol, marine microlayer and seawater as well as the particulate morphology, investigated by SEM, seem to support the hypothesis that particulate lead is transferred from the atmosphere to the water column through three different mechanisms: (i) release of SPM from the pack ice during its melting, (ii) input from the continental land through wet deposition, (iii) transport by aerosol and marine microlayer. Concentration data both in the whole organism and in some target organs indicated two suitable biomonitor organisms: the bivalva Laternula elliptica (particularly its digestive gland) and the fish Trematomus bernacchii (particularly its bones).

The Southern Ocean plays an important role in the global carbon cycle and, as a consequence, in the planetary climate equilibrium. The Ross Sea is one of the more productive regions in the Southern Ocean, due to strong phytoplankton blooms occurring during summer. Satellite remote sensing is a powerful tool for investigating such phenomena, especially if the bio-optical algorithms are tuned with in situ data. In this paper, after having compared the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the ENEA Lidar Fluorosensor (ELF), the SeaWiFS chlorophyll a (Chl a) algorithm is tuned in the Ross Sea by means of the ELF measurements. The Chl a concentrations obtained in this way have been the basis for estimating productivity values and their evolution during summer 1997–98. Three primary production models have been used, providing information on their accuracy and performance in the Antarctic environment. Our investigations suggest that the primary production was lower than usual during the period 3 December 1997–16 January 1998.

In this study, the impacts of the Antarctic Oscillation (AAO), the Pacific–South American teleconnection (PSA) and the El Niño–Southern Oscillation (ENSO) on Antarctic sea level pressure and surface temperature are investigated using surface observational data, European Centre for Medium-Range Weather Forecasts (ECMWF) 40 Year Re-analysis (ERA-40) and the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) re-analysis data from 1958–2001. There is the most significant correlation between PSA and Antarctic sea level pressure and surface temperature in the northern Antarctic Peninsula during four seasons. But the correlation between Southern Oscillation Index and surface temperature and sea level pressure is significant at some stations only in spring. The three indices can explain a large portion of the trends found in sea level pressure and temperature at some stations, but not at all stations. Among the three indices the most important contribution to the trends in the two surface variables comes from AAO, followed by PSA, and finally by ENSO. The two re-analysis datasets show great similarity for the trends in surface temperature and sea level pressure in April–May and October–November, but not December–February. In summer the trends in surface temperature and sea level pressure in East Antarctica for ERA-40 re-analysis are opposite to those of NCEP re-analysis.

A compositionally varied swarm of mafic dykes in the Jetty Peninsula area was emplaced about 320 Ma ago (K-Ar age). There are three major groups: Group 1 dykes range from transitional-alkaline dolerites to camptonites, Group 2 are trachydolerites, and Group 3 are diorite to quartz diorite porphyries. Group 1 dykes have very similar ratios of most incompatible elements and were derived from the same (or a very similar) enriched lithospheric mantle source region (∈Nd −0.18 to −3.05) with high Nb and Ta (i.e., OIB, ocean island basalt, characteristics). However, the presence of several distinct subgroups with different incompatible element abundances implies significantly different degrees of melting. Group 2 trachy dolerites are much more fractionated (mg 22–36), but were apparently derived from a similar, although somewhat more enriched (∈Nd −2.26 to −4.63) source. Group 3 diorites are compositionally quite distinct and may have been derived by intracrustal melting. Enrichment of the mantle source(s) of Groups 1 and 2 dykes apparently occurred about the same time as high-grade metamorphism in the area, and may have been coeval with crust formation in nearby parts of Gondwana.

A late summer study of marine bacteria activities, and the interrelationships with the microbial loop and the microbial food chain was carried out from 22 January to 10 February 2000 in a coastal area of Terra Nova Bay (Ross Sea). The objective was to investigate the transition from the end of a phytoplanktonic bloom to the start of winter. Intense bacterial activities, comparable to those of temperate marine environments, were observed. The carbon potentially mobilized from proteinaceous matter was quantitatively the most important source of carbon for the bacterioplankton. The leucine aminopeptidase activity was higher in January samples and decreased towards 10 February whereas an opposite trend was observed for alkaline phosphatase and �-glucosidase activities. The bacterial production was supported by c. 0.2% of the amounts of dissolved organic carbon mobilised by hydrolytic activities and by 7% of inorganic phosphate mobilised by alkaline phosphatase activity. A sharp reduction in the bacterial biomass, possibly due to zooplankton grazing or viral lysis, was observed for the first time in Terra Nova Bay.

Deschampsia antarctica Desv. is one of two vascular plants from the Maritime Antarctic. It is usually exposed to cold, salt, and desiccating winds. We hypothesize that D. antarctica has genes that encode dehydrin proteins and their expression is regulated by low temperature, salt or osmotic stress. To test this hypothesis a fragment of a dehydrin gene from D. antarctica was identified and used as a probe to study dehydrin expression under low temperature, salt, and osmotic stress, and exogenous ABA (abscisic acid) treatments. An anti-dehydrin antibody was also used to study dehydrin protein accumulation under the same treatments. Southern analysis of genomic DNA treated with different endonucleases showed more than four bands recognized by the probe, suggesting that D. antarctica has several dehydrin genes. Northern analysis showed two putative dehydrin transcripts of 1.0 kb accumulated only under exogenous ABA and 1.6 kb under osmotic and salt treatments, suggesting that D. antarctica would have ABA-dependent and - independent pathways for regulation of dehydrin expression. Western analysis showed seven dehydrin proteins (58, 57, 55, 53, 48, 30 and 27 kDa) under the different stress treatments. Cold-accumulated dehydrin proteins were immunolocalized, showing that they are associated with vascular and epidermal tissue, which are preferential ice nucleation zones.