The title of this editorial is virtually a refrain of modern international organizations. What some have called “the frozen demographics” seems to threaten the future of science in many fields, not least Antarctic science.

One of the most important elements of the Antarctic Treaty is the requirement to provide open and free access to all information collected south of 60° S. For this reason the current focus on making all published science free for everyone strikes a sympathetic cord. Led by various institutions promoting web posting of published material and the Public Library of Science enthusiasts proposing open access through the author-pays model there is a ferment of activity at present around the world to convert scientists and librarians to this new religion.

The limits of the Southern Ocean and its importance have been under debate for a long time. However, with growing knowledge, it has become obvious that the circum-Antarctic water belt is the defining limit and that the Southern Ocean plays an active and important role in the physical part of the global climate system, the global carbon cycle and biogeochemical processes.

When scientists from HMS Challenger dredged animals from over 5km depth, they finally laid to rest the azoic hypothesis of Edward Forbes, that life could not exist in cold dark depths of theocean, and thereby opened the doors to true deep-sea biology. The past decade has witnessed a furthersea change in our view of marine diversity, if I may be permitted the pun, a change driven to a largeextent by improved knowledge from Antarctica. For many years we viewed the tropics as the enginesof diversity; species arose in warm clear seas, especially those associated with coral reefs, and spreadslowly to populate the harsher high latitudes. Early studies of the isopod fauna had also suggested thatat least some organisms living on the continental shelf of Antarctica may have originated in the deepsea. After a period of intense work, much of it under the auspices of the SCAR EASIZ (Ecology of theAntarctic Sea Ice Zone) and more recently the EVOLANTA(Evolution in Antarctica) programmes, wecan now modify both hypotheses, with powerful implications for our understanding of global marinediversity. The marine invertebrate fauna of the Antarctic continental shelf is now better described thanmight be thought, and the total fauna may well exceed 17000 taxa. Interestingly, there are very fewplaces in the world with comparable data, but we can say that the fauna has had a long history ofevolution in situ and is not simply a last refuge for taxa that originated elsewhere.

On the basis of histological examination, we present the first description of oogenesis in H. spinosus. Eight stages of oocyte development were identified using morphological and histochemical criteria. The development of the oocytes is synchronous, and two clutches grow simultaneously in the ovary. Spawning takes place during the end of summer and the beginning of autumn. Absolute fecundity is low, ranging from 787 to 1504 oocytes. The low fecundity is probably related to parental behaviour. Our data indicate that the features of the reproductive biology of H. spinosus, in spite of its unusual environment, are similar to those observed in other teleost fish.

Abundance, diversity, and distribution of suprabenthic Isopoda caught from a water layer between 0.27 to 0.60 m above the seafloor were analysed. The samples were taken during the ANT XV/3 cruise on RV Polarstern by means of an epibenthic sledge along two transects in the southern Weddell Sea (Vestkapp and Halley Bay) and another one east of King George Island. At each of these three bathymetric transects, five to six stations were sampled between 200 and 2000 m. In total, 4258 specimens of isopods were sampled at 14 stations standardized to 1000 m2 hauls. 114 species were identified from 49 genera and 23 higher taxa (families and suborders) of Isopoda. Most of them belonged to the suborder Asellota. Dominant families are Munnopsididae (Eurycopinae, Ilyarachninae), Joeropsidae, Munnidae, Paramunnidae, Ischnomesidae and Desmosomatidae. No striking differences were found between areas (Vestkapp, Halley Bay, Kapp Norvegia, and Bransfield Strait). Overall isopod abundances were highest at the shallowest station; species richness was slightly higher above 1000 m depth.

The Southern Ocean is unique among the world's oceans in its linkage across the other major ocean basins, its rich and unusual marine ecosystem, and its interaction between the physical climate system and the biogeochemistry of the region. This paper provides an overview and conclusions of a meeting at the Royal Society in London in which an Earth System Science approach was taken to our present and future understanding of the Southern Ocean. A brief summary of what Southern Ocean science has achieved to date, challenges that need to be confronted, and the key questions for the future within an Earth System Science approach are provided.

The study describes the annual cycle of southern elephant seals for the increasing colony of Península Valdés, and compares it to the haul-out pattern reported for stable or decreasing sub-Antarctic colonies of the species. Data were collected during censuses of the entire colony (nine breeding seasons, two moulting seasons and one autumn–winter haul-out), monthly surveys of coastline and mark-recapture of pups. Pup production during the study period grew from 12 113 to 14 621 animals (1995–2003). Most relevant events of the cycle were similar for all colonies studied, independent of the geographical location, size or population trend. Compared with other locations where southern elephant seals breed and moult, distinct features for Península Valdés were: i) breeding occurs earlier in the spring, and ii) most adult females reproduce and moult in the same colony. The increasing number of animals ashore was correlated with the expansion in pup production. Population trends and stability of demographic events could be related to a consistent physical environment (ocean fronts) during foraging phases of the annual cycle.

Concentrations of major ions (Cl−, NO3−, SO42−, Na+, K+, Mg2+, Ca2+) were measured in melting snow and water samples from streams and lakes in ice-free areas throughout northern Victoria Land. Most ions in snow and terrestrial water derive from the marine environment and their concentrations are extremely variable in space and time, especially in water systems without melting snow and ice. The distance from the sea, snow sublimation, changes in water inflow, evaporative concentrations, weathering and drainage processes in the catchment, nesting seabirds and aquatic microbiota are among factors which most influence ion composition variability. Comparisons with data from twelve years ago in the same lakes indicate that the warming trend detected at Terra Nova Bay station during this period did not affect the biogeochemistry of water systems. Waters from a lake which recently experienced a lowering of the water level showed a remarkable increase in SO42− concentrations. We hypothesized that the differential mobility of sulphate salts in the Antarctic soils, the biosynthesis of sulphur compounds in the lake, and the progressive decrease of the water volume are factors involved in the increase of SO42− concentrations.

Time-series sediment traps were deployed to investigate the temporal evolution of particle fluxes in eastern and central Bransfield Strait, from December 1999–December 2000. Particle fluxes showed large seasonal variation at both trap sites. In eastern Bransfield Strait, summer mass fluxes were two orders of magnitude higher than winter mass fluxes, while in central Bransfield Strait, almost 99% of the annual mass flux (33 g m−2) was collected in a 40-day period from December–January. Export flux also exhibited a high regional variability. This regional variability is probably due to central Bransfield Strait's strong surface current, which carries most settling particles produced in the surface waters away from the mooring site during the low summer flux period. The relatively low biogenic silica to organic carbon ratios (a range of 0.29–1.4) and high lithogenic fluxes (41% of total mass flux) indicate that the growth of phytoplankton is not limited by the micronutrient iron in eastern Bransfield Strait. The annual flux of organic carbon in eastern Bransfield Strait was 6.8 g C −2, which is three times higher than the flux measured in central Bransfield Strait (2.2 g C −2). Organic carbon flux in eastern Bransfield Strait is relatively high for the Southern Ocean, possibly due to fast-sinking faecal pellets that lead to less decomposition of organic material in the water column. Calculations suggest that approximately 7.2% of the organic carbon produced at the surface in eastern Bransfield Strait is exported to a depth of 678 m. This exceeds the maximum calculated export of primary production to a depth of 1000 m in the Atlantic and Southern oceans.

Southern Ocean palaeocirculation is clearly related to the formation of a continental ice sheet on Antarctica and the opening of gateways between Antarctica and the Australian and South American continents. Palaeoenvironmental proxy records from Southern Ocean sediment cores suggest ice growth on Antarctica beginning by at least 40 million years (Ma) ago, and the opening of Tasmania–Antarctic and Drake Passages to deep-water flow around 34 and 31 ± 2 Ma, respectively. So, the Eocene/Oligocene transition appears to mark the initiation of the Antarctic Circumpolar Current and thus the onset of thermal isolation of Antarctica with a first major ice volume growth on East Antarctic. There is no evidence for a significant cooling of the deep ocean associated with this rapid (< 350 000 years) continental ice build-up. After a long phase with frequent ice sheets growing and decaying, in the middle Miocene at about 14 Ma, a re-establishment of an ice sheet on East Antarctica and the Pacific margin of West Antarctica was associated with an increased southern bottom water formation, and a slight cooling of the deep ocean, but with no permanent drop in atmospheric pCO2. During the late Pleistocene on orbital time scales a temporal correlation between changes in atmospheric pCO2 and proxy records of deep ocean temperatures, continental ice volume, sea ice extension, and deep-water nutrient contents is documented. I discuss hypotheses that call for a dominant control of glacial to interglacial atmospheric pCO2 variations by Southern Ocean circulation dynamics. Millennial to centennial climate variability is a global feature, but there is contrasting evidence from various palaeoclimate archives that indicate both interhemispheric synchrony and asynchrony. The role of the Southern Ocean, however, in triggering or modulating climate variability on these time scales only recently received some attention and is not yet adequately investigated.

Based on data from the Weddell Sea in the Atlantic sector of the Southern Ocean, the total number of macrozoobenthic species was estimated for the entire Antarctic shelf using species-accumulation methods, jack-knife estimators, and Incidence-based Coverage Estimators of species richness. Ranging between 11 000 and 17 000 expected species, Antarctica seems to have an intermediate species richness when compared to other selected tropical, temperate or Arctic habitats.

Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) concentrations were measured in marine surface sediments around the Brazilian station in Admiralty Bay, during the summers of 1997/98 and 1999/2000 using GC-FID and GC-MS. Total aliphatic hydrocarbons ranged from 0.15 to 13.28 μg·g−1 (dry weight) while n-alkanes varied between 0.10 and 9.63 μg·g−1. The highest concentrations were obtained at the sewage outfall, with decreasing levels away from the outfall. The distribution of n-alkanes showed significant quantities of long chain n-alkanes (n-C22 to n-C34) at sites near the Brazilian station that may be attributed to the station activities. A short chain n-alkanes sequence (n-C12 to n-C21) associated with diesel fuel arctic (DFA) was present in all the samples. Total PAHs varied from 9.45 to 270.5 ng·g−1. The higher PAHs level and the presence of an unresolved complex mixture only in sediment from the sewage outfall is an indication of oil contamination at this location. A slight increase in PAHs near the Brazilian station since 1993 may be attributed to an increase in the number of staff over recent years. In general, the concentration of AHs and PAHs was similar to that found in other Antarctic areas.

Early conceptual models and global climate model (GCM) simulations both indicated the likelihood of an enhanced sensitivity to climate change in the polar regions, derived from the positive feedbacks brought about by snow and ice. As GCMs developed, however, the expected enhanced sensitivity has been more robust in the North Polar Region than the South Polar Region. Some recent increased-CO2 simulations, for instance, show little change in Southern Ocean sea ice extent and thickness and much less warming in the Southern Ocean region than in the sea ice regions of the Northern Hemisphere. Observations show a highly variable Southern Ocean ice cover that decreased significantly in the 1970s but, overall, has increased since the late 1970s. The increases are non-uniform, and in fact decreases occurred in the last three years of the 1979–2002 satellite record highlighted here. Regionally, the positive trends since the late 1970s are strongest in the Ross Sea, while the trends are negative in the Bellingshausen and Amundsen seas, a pattern that appears in greater spatial detail in maps of trends in the length of the sea ice season. These patterns correspond well with patterns of temperature trends, but there is a substantial way to go before they are understood (and can be modelled) in the full context of global change.

The jaw musculature of notothenioid fishes is described and compared based on a total of 38 species referred to eight families of the suborder Notothenioidei. In the Notothenioidei, the adductor mandibulae, the largest and most conspicuous of the cranial muscles, is generally composed of sections A1, A2, A3 and Aw as in the generalized percoids. The morphology of the adductor mandibulae is similar in most notothenioid families except the Nototheniidae and Bathydraconidae. Notothenia, Paranotothenia and Dissostichus are clearly distinguished from the other nototheniid genera in having A3. Gymnodraco of the Bathydraconidae has a fused A1-A2 complex and the anterior element is segmented by a tendinous intersection from the A1-A2 complex. These features are unique to Gymnodraco and not seen in other bathydraconids. The Harpagiferidae and Artedidraconidae share the same apomorphy, the presence of A1β, with the Nototheniidae and have no synapomorphies with the Bathydraconidae and Channichthyidae. The character distribution, however, shows some inconsistencies with the previous classifications. Based on the limited evidence obtained in this study, the Notothenioidei can be divided into six groups and it seems reasonable to suggest a review of the current classification of the Nototheniidae.

Two new species of Paramunnidae (Crustacea, Isopoda, Asellota) from the South Shetland Islands (sub-Antarctic) are described. Austrosignum escandellae sp. nov. has long eyestalks, dorsum slightly sculpted (transverse bumps on pereonites 1–5), and lateral margins of pereonites rounded. The closest species is A. spinosum Kussakin, 1982 that also shows dorsum sculpted. The main differences are the ocular peduncle (short in A. spinosum) and the lateral margins of pereonites (pointed in A. spinosum). Coulmannia ramosae sp. nov. differs from the other two species of this genus (C. australis Hodgson, 1910 and C. frigida Hodgson, 1910) in that only the margins of pereonites 2–4 are expanded (into one point). A discussion of the Austrosignum/Munnogonium complex is provided with a comparative table of the species involved.

Samples of Chaenocephalus aceratus (Lönnberg) were collected during a trawl survey carried out around the South Shetland Islands in January–February 2002. Fish were caught by commercial bottom trawl fishing down to 500 m depth, using a stratified randomized sampling design. As observed in other recent surveys within the same area, C. aceratus represented one of the predominant species. Overall, 357 specimens ranging from 13 and 67 cm (TL) were selected for the present study. Ages were estimated by counting annuli present in the sagittal otoliths, exposed by grinding and polishing along their sagittal plane. To estimate the precision of age data, we compared blind readings by readers from different institutions. The age range was 1–17 years for females and 1–15 years for males. Von Bertalanffy growth curves were fitted to the estimated age-length data for each sex. The estimated values of asymptotic length L∞ (cm) and K (year−1) were respectively 79.8 and 0.07 for females and 60.0 and 0.09 for males. The growth performance index ranged between 2 and 2.5, similar to that reported in other icefish. Sexual maturity was attained by females and males at about 10 and 9 years old respectively, at about 60% of their maximum estimated age. These results are compared with age and growth data available in the literature for C. aceratus, and discussed in the light of recent commercial exploitation.

The hemispheric and regional atmospheric circulation influences the Southern Ocean in many and profound ways, including intense air-sea fluxes of momentum, energy, fresh water and dissolved gases. The Southern Ocean ventilates a large fraction of the world ocean and hence these influences are spread globally. We use the NCEP-2 reanalysis data set to diagnose aspects of the large-scale atmospheric structure and variability and explore how these impact on the Southern Ocean. We discuss how the ‘Southern Annular Mode’ and the ‘Pacific-South American’ pattern influence the Southern Ocean, particularly in the eastern Pacific. We review the importance of atmospheric eddies in Southern Ocean climate, and the role they play in the transport of mechanical energy into the ocean. The fluxes of fresh water across the air-sea boundary influence strongly the processes of water mass formation. It is shown that climatological precipitation exceeds evaporation over most of the Southern Ocean. When averaged over the ocean from 50°S to the Antarctic coast the annual mean excess is 0.80 mm day−1. The magnitude of the flux displays only a small measure of seasonality, and its largest value of 0.92 mm day−1 occurs in summer.

In the Antarctic ciliate, Euplotes focardii, the heat-shock protein 70 (Hsp70) gene does not show any appreciable activation by a thermal stress. Yet, it is activated to appreciable transcriptional levels by oxidative and chemical stresses, thus implying that it evolved a mechanism of selective, stress-specific response. A basic step in investigating this mechanism is the determination of the complete nucleotide sequence of the E. focardii Hsp70 gene. This gene contains a coding region specific for an Hsp70 protein that carries unique amino acid substitutions of potential significance for cold adaptation, and a 5' regulatory region that includes sequence motifs denoting two distinct types of stress-inducible promoters, known as “Heat Shock Elements” (HSE) and “Stress Response Elements” (StRE). From the study of the interactions of these regulatory elements with their specific transactivator factors we expect to shed light on the adaptive modifications that prevent the Hsp70 gene of E. focardii from responding to thermal stress while being responsive to other stresses.

Coupling between pelagic and benthic systems has been described in numerous shallow water communities. In Potter Cove, where pelagic primary production is low (not only during the Antarctic winter but also during the summer), the rich benthic community present there must depend on other food sources than phytoplankton. Over a year-round period we determined the abundance of the different seston particles which constituted the stomach contents of the Antarctic ascidian Cnemidocarpa verrucosa (Lesson, 1830) at Potter Cove. Stomach repletion was highest in November and lowest in June. Ascidians took in a wide range of particles from large detritus (macroalgal debris and faecal pellets) to minute particles < 5 μm. Large detritus and minute particles together represent the main percentage of contents throughout the year (mean 91%). Diatoms were a low percentage (mean 4.5%). Unidentified flagellates, dinoflagellates and coccolithophorids were scarce, with mean values lower than 4%. Among diatoms benthic species were more abundant in summer and pelagic ones prevailed from March to November. Resuspension of benthic material due to wind mixing and the input of allochthonous particles by currents are important mechanisms that ensure food for ascidians and the community of suspension feeders in Potter Cove.