Friesea grisea is the only springtail species currently described from both East (Victoria Land) and West Antarctica (Antarctic Peninsula), although levels of genetic divergence between the two regions suggest the possibility of cryptic species. Determining the genetic structure of populations in the two regions is necessary in order to compare the effects of the different environmental conditions in the two regions, the different evolutionary histories of their inhabitants, and for assessing any influence of latitude in each region on genetic diversity. We analysed sequences of the mitochondrial COX1 and ATP6 genes from a total of 111 individuals for 17 sites (nine on the Antarctic Peninsula and eight in Victoria Land), to assess levels of genetic diversity. Both regions have their own unique sets of haplotypes, differing by about 20% of their nucleotide sequences. A similar number of haplotypes was found in the two regions, and within each we found two groups of populations sharing no haplotypes. In the Antarctic Peninsula, two, presumably ancestral, haplotypes are dominant in frequency. In Victoria Land, the Cape Hallett population showed a distinct set of haplotypes, genetically different from the southernmost populations, suggesting differentiation on pre-Pleistocene timescales.

The first extended baseline studies of total gaseous mercury (TGM) and dimethylmercury (DMM) in Antarctica are reported. Mean TGM concentrations of 0.52, 0.60 and 0.52 ng m−3 were obtained for three consecutive years at the southern tip of Ross Island (77°S). The levels of DMM in Antarctica are less than 10% of the TGM, and frequently fall below the limit of detection. These results represent the lowest TGM concentrations recorded globally and extend into polar regions the observation of a decrease in atmospheric mercury concentration with increasing latitude.

Population fecundity and reproductive habits in Patagonotothen tessellata were established for each reproductive period during 1988 and 1989. Fecundity/total length and fecundity/total weight relationships were analysed through regression models. Fecundity was positively correlated with fish length and weight. Mean fecundity was 25932 eggs (range 7634–62033). The regressions for each reproductive period are similar, suggesting that the amount of energy allocated to reproduction does not vary between spawning periods. Parental behaviour is described from both field and laboratory observations. Nesting and parental care were carried out by P. tessellata males. The life history strategy of this species is discussed in relation to that of other nototheniid species.

Martialia hyadesi were collected from fishing vessels at the Antarctic Polar Frontal Zone (APFZ) and the Patagonian Shelf Edge (PASE) during the 1989 austral autumn and winter. Squid were measured, weighed, assigned a maturity stage and the paired statoliths were removed. Statolith sections revealed concentric growth rings using light and scanning electron microscopy. Counts of these putative daily micro-growth increments were made directly and by an estimating procedure. Energy dispersive (ED) and wavelength dispersive (WD) x-ray analyses of Sr and Ca content were made on subsamples of statolith sections. Estimated increment counts, which were generally higher than direct counts, were adopted for routine application. Back calculated hatching dates showed that a single cohort, with a relatively narrow size range, was sampled in each geographical area. Back calculations suggested that M. hyadesi at the APFZ had hatched in the austral winter and those at the PASE had hatched in the spring. At the PASE, growth rate was estimated to be some 30% higher than at the APFZ and PASE squid were more mature at a given age. The hypothesis that the Sr:Ca ratio along the growth axis of the statolith contains information on thermal history was examined. Sr:Ca ratios in the statolith fell in the range 0.009–0.017 and varied systematically but this variation did not apparently relate to season and ratios were not significantly different between geographical areas. A consistent feature was a relatively low Sr:Ca ratio at the time of hatching. According to the Sr:Ca thermometer hypothesis this is consistent with spawning in relatively warm water but it could equally be due to depositional differences during early statolith growth. The Sr:Ca thermometer hypothesis could neither be confirmed nor rejected by the data but there is evidence that strontium varies systematically with age in the squid statolith.

The ecology of two meltwater streams on King George Island, Ornithologists Creek (with penguin rookeries close to its lower reaches) and Petrified Forest Creek (a highly oligotrophic system), was studied during the 1996–97 summer season. To estimate seasonal productivity of the periphyton and to establish which environmental parameters influenced periphyton growth most strongly, two types of artificial substrata (fibreglass nets – ash-free dry weight (AFDW), and microscope slides – Chlorophyll a (Chl a)) were tested in situ. Thus relative periphyton productivity (RPP) reflects algal colonization and growth as well as losses due to cell mortality and abrasive action of moving sediments. The Petrified Forest Creek was more productive (AFDW = 108.63 μg cm−2 d−1, Chl a = 0.35 μg g cm−2 d−1) than the Ornithologists Creek (AFDW = 69.90 μg cm−2 d−-1, Chl a = 0.26 μg cm−2 d−1). RPP differed both along the streams, and during the season. Significant positive or negative relationships (generalized linear models) were found between RPP and streamwater ‘physico-chemical parameters’ and ‘geomorphological-geographical characteristics’ of the streams' catchments. In addition, in the lower reaches of both streams almost no active colonization or growth was recorded. In the Petrified Forest Creek, the periphyton biomass was so high that mainly passive organic matter deposition occurred. By contrast, in the lower reach of Ornithologists Creek, periphyton colonization and growth was around zero, being negatively influenced by penguin excrement. Ornithologists Creek was richer in nutrients (DIN, DRP), which also fluctuated more widely along its length and throughout the season, than in the Petrified Forest Creek. Parameters associated with the inorganic carbon cycle of the streamwater reflect higher RPP in Petrified Forest Creek. Moreover, RPP was higher in stream reaches with higher amounts of gravel boulders on the bottom.

Studies of the recovery of the fauna following the 1967–70 eruptions at Deception Island, South Shetland Islands, have made it one of the best-studied marine sites of the Southern Ocean for biodiversity. Using SCUBA we surveyed the mega- and macro-epifauna of its subtidal zones in the entrance (Neptune's Bellows), immediately inside the caldera (Whaler's Bay) and well within the caldera (Fumarole Bay). Richness declined from 10 phyla, 13 classes and 35 species at Neptune's Bellows to three phyla, four classes and five species in Whaler's Bay and just two phyla, classes and species at Fumarole Bay. Amongst the 35 species we found at Neptune's Bellows, 14 were previously unrecorded from Deception Island. Despite many ship visits and amongst the warmest sea temperatures in the Southern Ocean, the Non Indigenous Species (NIS) algae were not found in our survey. Deception Island has been recolonized considerably since the recent eruptions, but many taxa are still very poorly represented and the colonizers present are mainly those with planktotrophic larvae. Examination of the literature revealed that to date 163 named marine species have been found within the caldera as well as at least 50 more morphospecies, which are yet to be identified. Species accumulation has consistently increased across eight recent samples reported and the number of species reported there is likely to reach 300 when taxa such as the nematodes are identified to species level. This represents a first meaningful total species estimate for an Antarctic marine area and, as the site is comparatively impoverished, indicates how rich the surrounding Antarctic shelf must be.

Snow temperatures measured at around 10 m depth over the period 1957–1992 have been used to derive a map of mean annual snow surface temperature corrected to sea level over the Antarctic Peninsula and Filchner-Ronne Ice Shelf. Multiple linear regression analysis has been used to calculate rates of change with latitude, longitude, altitude and time, for data to the west and east of the topographic divide running along the spine of the Antarctic Peninsula. Climate warming on the Filchner-Ronne Ice Shelf follows the trend observed at Halley Bay, a coastal station nearby. High spatial variability leads to uncertainty in the temporal trend for mean annual snow surface temperature in the Antarctic Peninsula but there is some indication that the large trends observed at Faraday and Marguerite Bay, two stations on the west coast of the peninsula, are attenuated inland.

Present day Southern Ocean benthic biodiversity is the result of climatic changes based on the break-up of Gondwana in the Cretaceous and the Cenozoic and the physiological potential of the fauna to cope with the climatic deterioration. Though many taxa survived the thermal drop in ocean bottom temperatures, zoogeographic ranges changed and some faunal elements even became extinct, e.g. benthic decapods and teleost fish, opening up new ecological niches and the potential for enormous adaptive radiations within some taxa, like the amphipods and isopods (peracarid crustaceans) and notothenioid fish. Ice-sheet extensions and retreats might have enhanced speciation processes as well as eurybathy. Biodiversity on the Antarctic shelf is high within the polychaetes, molluscs, and echinoderms, and within the amphipods and isopods possibly due to the Cenozoic extinction of the benthic decapods. Moreover, some shelf areas are characterized by accumulations of large suspension feeders like poriferans, bryozoans, ascidians, gorgonians, and hydroids. Palaeoclimatic changes also caused that many taxa of the modern, present day Southern Ocean benthic organisms are characterized by gigantism, slow metabolism, longevity, and a reduced number of offspring combined with late maturation. However, our biological knowledge is mainly confined to Southern Ocean shelf organism; we do not know much about the composition, biodiversity and zoogeography of the Southern Ocean deep sea animals. On this background the deep sea expeditions ANDEEP were born and the background and first results of these are presented herein.

Deception Island volcano (South Shetland Islands, Antarctica) has been monitored in summer surveys since 1994. We analyse the seismicity recorded from 1999–2011 with a local network and seismic arrays. It includes long-period (LP) events, volcanic tremor episodes and volcano-tectonic (VT) earthquakes. Long-period events are conspicuous, ranging from 58 (2007–08) to 2868 events (2003–04). The highest number of LP events in one day is 243 on 2 February 2001, and there are several discrete periods of intense LP activity. These variations may be related to alterations in the shallow hydrothermal system of Deception Island. The number of VT earthquakes recorded during the surveys range from 4 (2008–09) to 125 (2007–08). In some periods VT distributions are temporally and spatially homogeneous, with a generally low level of seismicity. In other periods we observe a peak of VT activity lasting a few days, concentrated in a particular area. These two patterns may respond to different processes, involving regional stresses and local tectonic destabilization induced by volcanic activity. Overall, this study indicates that over the period 1999–2011 the volcano presented a moderate level of seismicity, and suggests that there has been no significant reactivation of the volcano since the 1999 seismic crisis.

The late Proterozoic basement of the Porthos Range northern Prince Charles Mountains, east Antarctica, is dominated by a suite of felsic to mafic granulites derived from igneous and, less importantly, sedimentary protoliths. Compositionally, they are broadly similar to granulites occurring along the Mac. Robertson Land coast and southern Prince Charles Mountains. Ultramafic to mafic orthopyroxene' + clinopyroxene granulites with relict igneous layering occur as lenses within the felsic to mafic granulites, and show compositional evidence of a cumulate origin. The felsic to mafic granulites are intruded by several large charnockite bodies that have similarities to the Mawson Charnockite, and may have formed via a two-stage partial melting process. The charnockite and host granulites are chemically very similar, and both may have been derived from a common middle to lower crustal source region. Undepleted K/Rb ratios suggest retention of original chemistry, with variations being due to fractionation processes. Normalized trace element patterns resembling modern-day arc settings suggest that the Porthos Range granulites were possibly generated in a subduction zone environment.

Two species of euphausiids (Thysanoessa macrura Sars and Euphausia vallentini Stebbing) from the Southern Indian Ocean were analysed for their lipid content, fatty acid and fatty alcohol composition, in relation to developmental stage (T.m) and sex (E.v). Lipid composition showed wax esters and triacylglycerols as main neutral lipids for T. macrura and E. vallentini respectively. Allometric relationships between lipid class and total lipids indicated that changes in total lipids were size dependent and mainly related to wax esters in T. macrura and polar lipids (both phosphatidylcholine or PC and phosphatidylethanolamine or PE) in E. vallentini. No difference in lipid composition could be shown for male and female E. vallentini, while sampling location, developmental stage and sex were significantly influential in T. macrura. In this latter species wax esters displayed relatively similar fatty acid and alcohol composition in both juvenile and female stages, whereas a striking difference could be seen between females and juveniles in terms of polar lipids with a very low PE content in females. Male and female E. vallentini showed little differences in fatty acid structure with the exception of PC in females, which were low in 22:6n-3. The trophic status of these two species was established using multivariate discriminant analysis, which indicated for E. vallentini a degree of omnivory similar to E. superba, while these T. macrura appeared more omnivorous than individuals collected in other areas of the Southern Ocean. Clustering of polar lipid composition suggested a link between differences in PC fatty acid and the post-spawn stage of the female of E. vallentini collected. The same probably applies for the changes in PE recorded for T. macrura females.

The Antarctic toothfish (Dissostichus mawsoni) exhibits a circumpolar distribution in coastal waters south of the Antarctic Polar Front. For a preliminary evaluation of global population structure in this species, we examined four mitochondrial regions and 13 nuclear gene fragments in samples from four CCAMLR Subareas in the Southern Ocean (Australian Antarctic Territory (Subarea 58.4.2), Ross Dependency (Subareas 88.1 and 88.2) and the South Shetland Islands (Subarea 48.1). Significant genetic differentiation within and among locations was observed for both mitochondrial and nuclear loci. The single nucleotide polymorphism (SNP) markers developed here will be useful for more extensive analyses of population structure in this species.

Antarctic fishes survive freezing through the secretion of antifreeze glycoproteins (AFGPs), which bind to ice crystals to inhibit their growth. This mode of action implies that ice crystals must be present internally for AFGPs to function. The entry and internal accumulation of ice is likely to be lethal, however, so how do fishes survive in its presence? We propose a novel function for the interaction between internal ice and AFGPs, namely the promotion of ice uptake by splenic phagocytes. We show here that i) external mucus of Antarctic notothenioids contains AFGPs and thus has a potential protective role against ice entry, ii) AFGPs are distributed widely through the extracellular space ensuring that they are likely to come into immediate contact with ice that penetrates their protective barriers, and iii) using AFGP-coated nanoparticles as a proxy for AFGP adsorbed onto ice, we suggest that internal ice crystals are removed from the circulation through phagocytosis, primarily in the spleen. We argue that intracellular sequestration in the spleen minimizes the risks associated with circulating ice and enables the fish to store the ice until it can be dealt with at a later date, possibly by melting during a seasonal warming event.

Phyllolepid placoderm remains from the Aztec Siltstone fish fauna are described as Austrophyllolepis quiltyi sp. nov., Austrophyllolepis cf. A. youngi, Placolepis tingeyi sp. nov., and phyllolepid indet. The new Antarctic species of two genera previously only known from Australia reinforce evidence from other fish taxa of close biogeographic affinity, as part of the eastern margin of Palaeozoic Gondwana. At least three genera and four species gives the Aztec Siltstone fish fauna the most diverse phyllolepid assemblage known, and probably the oldest documented so far (?late Middle Devonian). Specimens of Austrophyllolepis from the type locality at Mount Howitt, Victoria, are refigured for comparison with the Antarctic species. The order Phyllolepida is a key group for understanding Devonian vertebrate biogeography and palaeogeography, with a unique disjunct distribution in both time and space between the Southern and Northern hemispheres. Phyllolepids document one of the major dispersal events in early vertebrate history, which approximately coincided with the Frasnian–Famennian boundary mass extinction during the Late Devonian.

Deception Island is a large volcanic centre in Bransfield Strait, a very young marginal basin between the South Shetland Islands and Antarctic Peninsula. It has a historical record of volcanic activity, with the most recent eruption occurring in 1970. The island is a stratovolcano with a large flooded caldera forming a natural harbour known as Port Foster. It has been a focus of human activity since early last century, as a base for whaling and sealing expeditions and the locus of several scientific stations. During that period, many bathymetric surveys were carried out, the earliest in 1829 and the most recent in 1993. This study concentrates on surveys from 1948 onwards. Because Port Foster can be classified as a restless caldera, the bathymetric records were analysed for evidence of volcano-tectonic deformation, particularly caldera resurgence (uplift) which could have significant consequences for hazard and risk assessments of the volcano. The results show that a distinctive pattern of shallowing and uplift is present, correlating well with known and inferred volcanic and volcanotectonic processes on the island. In particular, bathymetric records between 1949 and 1993 show uplift rates as high as 0.3–0.5 m a−1, far exceeding normal sedimentation rates in a caldera this size. Rapid uplift in an arcuate offshore area not affected by the sedimentation of recent eruptions suggests that volcano tectonic resurgence or tectono-magmatic effects of an upward migrating magma chamber present a significant risk to the considerable human activity taking place in the region.

The Weddell Polynya, a large expanse of water that originated over Maud Rise (a bathymetric protrusion centred near 64°30′S, 3°E) and remained open during winter in the late 1970s, may have manifested a mode of deep ocean convection where despite large heat loss at the surface, sustained heat transport from below prevents lasting ice formation. In a different dominant mode (the present one), sea ice forms early in the winter and subsequently provides a thermal barrier that quickly quells incipient deep convection, thus preventing wholesale destruction of the ice cover. A possible mechanism for overcoming the thermal barrier is thermobaricity, the pressure dependence of the thermal expansion factor for seawater. An idealized, two-layer version of actual temperature and salinity profiles from the Weddell illustrates that thermobaric mixing can persist for extended periods in an ice-covered ocean, provided realistic melt rates (controlled by salt exchange at the ice/ocean interface) are specified. This furnishes a possible explanation for transient winter polynyas sometime observed in the ice-covered Southern Ocean. Thermobaricity may provide a trigger for widespread convection with possible climate impact.

Annual land-fast ice, particularly an unconsolidated layer or “platelet ice-like” layer (PLI), was sampled in spring 1995 to study the spatial and short-term variations of ice-associated diatoms. Under-ice water, a lead and small polynyas were also sampled. Along a 7 km seaward transect a geographical gradient was evident, with some rare diatom species present only in the offshore PLI, whereas others (mainly pennate diatoms) were ubiquitous. The dense microphytic PLI community as well as the phytoplankton was diatom-dominated, but, within these two communities, marked differences appeared. First, the sea-ice communities (PLI and solid bottom ice) were moderately diverse (36 species), mostly composed of pennate diatoms, of which many were chain forming or tube-dwelling. Dominant taxa were Navicula glaciei, Berkeleya adeliensis, Nitzschia stellata, Amphiprora kufferathii and Nitzschia lecointei. Some differences in the distribution of the most dominant species appeared within the bottom ice and the PLI, attesting to differences in the origin or/and growing capability of these diatoms in these two ice compartments. Under-ice water species composition was mixed with sea-ice communities only on the most coastal sites and during ice melt. Maximum cell numbers were mostly noticed in the PLI, reaching up to 1010 cells l−1 and very high Chl a concentrations (exceptionally up to 9.8 mg Chl a l−1 or 1.9 g Chl a m−2, from a 10 to 20 cm thick PLI layer, close to the continent). Secondly, the phytoplankton in the lead and small polynyas had a low diversity, very low standing stocks (on an average 0.69 μg Chl a l−1) and cell densities (2 × 104 cells l−1). Some species from the polynyas were similar to those of the PLI, such as Navicula glaciei, but others were typically planktonic, such as Chaetoceros cf. neglectus. The presence of encysted cells (Chaetoceros and Chrysophytes) was also noticeable in the polynya water. In early spring no seeding process was obvious from the PLI to polynya water. A comparison with similar fast-ice diatom communities in other parts of coastal Antarctica, is presented.

The Weddell Sea is one of the key regions of the Southern Ocean with respect to climate as most of the Antarctic Bottom Water (AABW) that occupies the world ocean deepest layers is likely to originate from this region. This study applies the Optimum Multiparameter water mass analysis to the Weddell deep waters in order to investigate their distribution and variability. The dataset used is based on the WOCE repeat sections in the area (SR04 and A12) from 1984 to 1998. The mean water mass distribution is consistent with previous knowledge of the region, along with high interannual variability. Regarding the temporal variability, it seems that the years of maximum Weddell Sea Deep Water (WSDW) contribution correspond to the lowest levels of Weddell Sea Bottom Water (WSBW), and vice versa. In order to identify possible forcing mechanisms for such variability, the water mass temporal anomalies were compared with oceanic and atmospheric modes of variability in that region such as the Southern Annular Mode (SAM). An apparent correlation between the SAM index temporal gradients and WSBW anomalies indicate that the Weddell Sea export of dense waters to the world ocean may be linked to that index on several time scales.

The barotropic and baroclinic tides in the Ross Sea were simulated using a primitive equation, sigma-coordinate model, the Regional Ocean Model System (ROMS), for four tidal constituents, M2, S2, K1, and O1. Small elevation amplitudes were predicted over most of the basin, with a combined standard deviation of 30–50 cm. Larger amplitudes, with standard deviations ranging from 50–70 cm, occurred deep within the ice shelf cavity, over the continental slope, and over Iselin Bank. Most of the elevation response was associated with the diurnal constituents (K1 and O1), as was most of the depth-independent (barotropic) velocity response. Baroclinic tides were generated at locations of steep topography for the semidiurnal constituents, but not the diurnal. Diurnal continental shelf waves were generated by the diurnal tides and found to amplify the semidiurnal elevations and baroclinic tidal velocities over the continental slope. Comparisons with observations in both elevation and velocities showed very good agreement for the semidiurnal constituents (M2 and S2) and moderate agreement for the diurnal constituents (K1 and O1). The disagreement for the diurnal constituents was associated with diurnal frequency continental shelf waves, which were overexcited along the shelf break. The baroclinic tides induced both small-scale horizontal and vertical shear in the velocity fields in the Ross Sea.

Evidence is provided from a sediment core from saline Abraxas Lake, Vestfold Hills, that indicates that the lake existed through the Last Glacial Maximum. It can therefore be concluded that at least part of the Vestfold Hills also remained ice-free through the Last Glacial Maximum, or at most was covered by a thin, non-erosive cold-based ice sheet. The evidence for the continued existence of Abraxas Lake includes a 14C date that significantly predates the Last Glacial Maximum (though this cannot be considered direct proof of the existence of the lake prior to the Last Glacial Maximum); the presence of saline porewater throughout the core, including in compacted sediments deposited during the glacial period, which implies that the lake obtained its salt prior to any Holocene marine highstand; and the occurrence of marine-derived fauna from the onset of significant biological activity late in the Pleistocene. The occurrence of ice-free land in the Vestfold Hills and similar oases suggests that the margin of the polar ice cap did not reach far beyond its current position at the Last Glacial Maximum, at least in regions now occupied by these oases.