Radiocarbon dating was carried out on the total organic carbon of 19 lacustrine and marine sediment samples from the Bunger Hills. The results indicate that radiocarbon contamination is negligible throughout two sediment sequences from a fresh water lake. In contrast, two sequences from marine basins are irregularly influenced by the Antarctic Marine Reservoir Effect, which today amounts to more than 1000 years, depending on the degree of dilution with meltwater. All dated sediments were deposited during Holocene time.

The 16S rRNAs of nine new species of prokaryotes, that had been isolated from four lakes of the Vestfold Hills, have been sequenced. These sequences were compared with those of their closest taxonomic relatives available from publicly available databases. The Antarctic species were of wide diversity with representatives from the domains Archaea and Bacteria (sensu Woese). Generally, they were most closely related to organisms from marine environments. The sequence dissimilarity between the rRNA sequences of the Antarctic strains and their nearest known relatives suggest they diverged from each other much earlier than the establishment of their modern Antarctic habitat. The conserved nature of the 16S rRNA molecule suggests it may not be as useful for detecting evolutionary change in Antarctic prokaryotes as distinct from non-Antarctic prokaryotes. Although the optimal temperature for growth of each species is well above the temperature of its environment, each has a reduced optimal temperature for growth when compared with its taxonomic counterpart from non-Antarctic environments. The vast majority of Antarctic prokaryotes remains to be described.

In certain regions of the Southern Ocean, tidal energy is believed to foster the mixing of different water masses, which eventually contribute to the formation of deep and bottom waters. The Ross Sea is one of the major ventilation sites of the global ocean abyss and a region of sparse tidal observations. We investigated M2 tidal dynamics in the Ross Sea using a three-dimensional sigma coordinate model, the Regional Ocean Model System (ROMS). Realistic topography and hydrography from existing observational data were used with a single tidal constituent, the semi-diurnal M2. The model fields faithfully reproduced the major features of the tidal circulation and had reasonable agreement with ten existing tidal elevation observations and forty-two existing tidal current measurements. The differences were attributed primarily to topographic errors. Internal tides were generated at the continental shelf/slope break and other areas of steep topography. Strong vertical shears in the horizontal velocities occurred under and at the edges of the Ross Ice Shelf and along the continental shelf/slope break. Estimates of lead formation based on divergence of baroclinic velocities were significantly higher than those based on barotrophic velocities, reaching over 10% at the continental shelf/slope break.

Eight hundred photosynthesis-irradiance relationships were determined in the shelf waters adjacent to Palmer Station, Antarctica during the spring/summer periods of 1991–94. Biomass specific maximum photosynthetic rate, PBmax, and the light limited photosynthetic efficiency, αB, were poorly correlated to the physical forcing and nutrient regimes at the sampling stations. The two photosynthetic parameters, however, did strongly covary indicating the minimum irradiance required to saturate photosynthesis, Ik, was relatively constant in this highly variable environment. The variability in Ik could partially be attributed to both depth in the water column and time of the year, with the highest values occurring for surface samples during the summer period of peak incident irradiance. Given this and the significant dependence of Pmax on phytoplankton biomass, a simple empirical model for primary productivity was developed. An independent test of the model was performed on data collected in a mesoscale offshore grid and predicted primary production was found to be within 13% of measured values. Although there are limitations to this approach (i.e. exclusion of diel periodicity in photosynthetic response), these results provide relatively robust estimates of daily primary production for the Southern Ocean.

The Maritime Antarctic is one of the regions where regional climate change is most intense and the reproductive performance of plants may be enhanced. Reporting the distribution of Deschampsia antarctica and Colobanthus quitensis on Byers Peninsula (Livingston Island, South Shetland Islands), our results confirm that D. antarctica is more widespread than C. quitensis. Flower and seed development of both species varied between sites. Deschampsia antarctica produced more viable seeds than C. quitensis, although fully developed seeds were not found at all locations. Seed production in C. quitensis was low in comparison with other Antarctic locations. The largest cushions of Colobanthus observed in 2002 were 15 cm in diameter, suggesting that the populations may have established at least 50 years ago. Deschampsia antarctica tussocks were very often 20 cm in diameter, although turf areas up to 1.5 m across were also observed, probably due to coalesced aggregates of individuals. This study shows that, although seed production is low, the presence of seedlings and young individuals suggests an expansion process.

During the early Pliocene a dynamic marine-based ice sheet retreated from the Wilkes Land margin with periodic ice advances beyond Last Glacial Maximum position. A change in sand provenance is indicative of a more stable Mertz Glacier system during the Late Pleistocene. East Antarctic Ice Sheet (EAIS) dynamics were evaluated through the analysis of marine diamictons from Integrated Ocean Drilling Program (IODP) site U1358 on the Adélie Land continental shelf. The warmer than present conditions of the early Pliocene coupled with the site's proximity to the landward sloping Wilkes Subglacial Basin provided the rationale for the investigations at this site. Based on visual core descriptions, particle size distributions, and major and trace element ratios, we interpret the origin of lower Pliocene strata by intermittent glaciomarine sedimentation with open-marine conditions and extensive glacial advances to the outer shelf. Heavy mineral analyses show that sand-sized detritus in the lower Pliocene strata was sourced from local intermediate to high-grade metamorphic rocks near Mertz Glacier. In contrast, Pleistocene diamictons exhibit a larger contribution from a prehnite-pumpellyite greenschist facies suggesting supply via iceberg rafting from northern Victoria Land. From this sedimentological evidence, we postulate a shift from a dynamic EAIS margin in the early Pliocene to possible stabilization in the Pleistocene.

An assessment is made of the ability of the Coupled Model Intercomparison Project 5 (CMIP5) models to represent the seasonal cycles of biogeochemistry of the Ross Sea over the late twentieth century. In particular, sea surface temperature, sea ice concentration, surface chlorophyll a, nitrate, phosphate and silicate, and the depth of the seasonal thermocline (measuring vertical mixing) are examined to quantify the physical-biogeochemical capabilities of each model, and to provide for ‘ranked’ model ensembles. This permits critical assessment of modelled Ross Sea biogeochemical cycling, including less well observed variables such as iron and vertically integrated primary production. The assessment enables determination of model output confidence limits; these confidence limits are used to examine future model scenario projections for consideration of potential ecosystem changes. The future scenarios examined are the representative concentration pathways rcp4.5 and rcp8.5. Our study suggests that by the end of the twenty-first century under rcp4.5 and/or rcp8.5 that there will be average increases in sea surface temperature, surface chlorophyll a, integrated primary production and iron, average decreases in surface nitrate, phosphate and silicate, and relatively large decreases in the depth of the seasonal thermocline and percentage coverage by sea ice in the Ross Sea.

The short term degradation of ‘Arabian light’ crude oil was followed under various seasonal conditions in coastal seawater at Iles Kerguelen. Artificial degradation experiments were carried out in 3 m3 tanks. In situ experiments were conducted in free-floating, semi-enclosed chambers permitting direct contact between the crude oil and the marine environment. Daily sampling allowed a regular survey of the bacterial changes of the oil contaminated seawater. All samples were analysed for total bacteria, heterotrophic viable microflora and hydrocarbon utilizing microflora. At the end of experiments, the remaining oil was carefully collected for rough quantitative estimation of hydrocarbon degradation. All the results clearly revealed a significant increase in the three types of bacterial microflora after the addition of crude oil. However, the data suggest that the initial state of the bacterial communities is important. Thus, the seasonal variations in the bacterial responses to hydrocarbon addition can be related to the differences in the natural bacterial populations involved. In all cases the wall effects observed in batch systems were reduced with in situ incubations.

The analysis of two high resolution hydrological datasets acquired during the 1997 and 2001 summers across the Antarctic continental shelf-break near Cape Adare (Ross Sea) is presented. The main focus of these cruises was the investigation of the overflow of the High Salinity Shelf Water (HSSW). This dense and salty water mass forms along Victoria Land and flows northward, descending the slope near Cape Adare. Water types characterizing the study area are detected through vertical salinity profiles and by the horizontal distributions of the temperature and salinity. Temperature and salinity hydrological sections obtained by means of objective analysis method well describe the water masses interactions at the shelf/slope edge. The 1997 dataset shows evidence of a strong HSSW signature on the slope, but it is difficult to quantify the spatial scales involved in the spreading mechanism, because the overflow takes place at the edge of the investigation area. The 2001 data, collected at the same position with improved spatial and temporal resolution, clearly indicates the absence of a “true” HSSW downslope process. Even though no estimation of the amount of downslope flow can be given at present due to the resolution of the available dataset, it is possible to get a better phenomenological picture of the process by comparing the two years.

Both bacterial culture and molecular approaches were used to investigate the bacterial diversity inside the Chinese Antarctic Great Wall Station and in its adjacent area. Heterotrophic bacteria were isolated from the samples using a direct plating method. γ-Proteobacteria, Actinobacteria, Flavobacteria and Firmicutes were isolated from these samples. In the three water samples, Pseudomonas species were dominant. In soil samples, Flavobacterium, Bacillus or Arthrobacter species dominated. Escherichia coli strains were isolated only in two samples from inside the station. Total cell counts in the six soil samples were semi-quantified by Quantitative Competitive-PCR of the 16S rRNA gene copies. The soil samples contained 105 to 109 cells g−1. Denaturing gradient gel electrophoresis (DGGE) was used further to investigate the bacterial diversity in the soil samples. A wider range of bacterial diversity including α-Proteobacteria, β-Proteobacteria, δ-Proteobacteria, γ-Proteobacteria, Flavobacteria, Actinobacteria and unclassified bacteria was discovered.

The aim of this study was to evaluate the hypothesis that Deschampsia antarctica Desv., the only grass of the Maritime Antarctic, responds to temperatures higher or lower than its optimum for photosynthesis (13°C), with the accumulation of heat shock proteins. The LT50 was determined in plants acclimated at 4°C (cold-acclimated plants) and in plants grown at 13°C (control plants) by membrane damage and by the activity of respiratory dehydrogenases. The LT50 was 48.3°C in both groups of plants when determined by membrane damage. When the LT50 was determined by the activity of respiratory dehydrogenases, this was, without significant difference, 47.8°C in cold-acclimated plants and 46.5°C in control plants. Western blot analyses were performed to investigate the accumulation of HSP70 at different temperatures. The optimal temperature for HSP70 accumulation was 35°C in cold-acclimated and control plants. Cold-acclimated plants subjected to a thermal stress of 35°C accumulated HSP70 protein more than control plants subjected to 35°C. After eight hours of continuous stress at 35°C, the maximum relative content of HSP70 in cold-acclimated plants was 1.9 fold higher than control plants. The threshold temperature for HSP70 accumulation was lower in cold-acclimated plants than in control plants. It is concluded that D. antarctica is able to tolerate heat stress with an LT50 similar to those of heat tolerant plants and that the cold-acclimated plants accumulate higher levels of HSP70 than those grown at 13°C.

Twenty five species of Polychaeta were recorded in soft bottom samples collected from 4–30 m. Total abundance of polychaetes ranged from 60 to 3300 m-2. High abundance values were locally recorded for Microspio moorei, Tharyx epitoca and Ophelina syringopyge. These species, together with more regularly distributed Capitella capitata and Scoloplos marginatus, constituted over 70% of all specimens. Total biomass value of the polychaetes varied between 3.8 and 46.4 gm-2. Travisia kerguelenensis and Aglaophamus ornatus constituted over 75% of total biomass. Species composition, richness and diversity of the polychaete assemblage varied with depth. Two parts of the investigated bottom section, differing in the polychaete assemblages structure, were distinguished; the first one in the depth range from 4–20 m and the second one at the depths of 25–30 m. On the basis of both new and previously published data two types of polychaete assemblages of the shallow soft bottom of the Antarctic sublittoral were distinguished. The type of sediment seems to be the main factor influencing the composition of polychaete assemblages.

A series of benches on nunataks of Alexander Island (Antarctica) are described. An increase in bench size with distance away from the retreating glacier suggests an age spectrum. The benches have thermal contraction cracks (in bedrock) on shallower, upper sections of the risers as well as salt encrusted runnels on the steeper lower section of the tread. The benches also show a distinct orientational preference (orientated to the north through to west) and, from first principles, these seem to be the aspects with optimal freeze-thaw cycles and temperatures conducive to thermal stress fatigue. The extensive dilatation associated with the retreating glaciers is thought to play a significant role in the origin and development of the benches as the combination of extensive jointing and optimal process conditions are thought to constrain where benches begin. The jointing, aided by the thermal contraction cracking, then facilitates extension and continued weathering of the treads. It would appear that these benches are examples of so called “cryoplanation terraces” that have been reported as fossil forms in Europe and North America. The study of such active forms in the Antarctic may provide good analogues for fossil features found in the Northern Hemisphere.

Asterozoans (Echinodermata) of Late Miocene age (6.02 ± 0.12 Ma) are preserved as external moulds in water-lain tuffs of the James Ross Island Volcanic Group (JRIVG), James Ross Island, Antarctic Peninsula. The asterozoans are complete, and appear to represent specimens suffocated after having been pinioned by rapid sedimentation on the distal fringe of an erupting sub-aqueous tuff cone. Although the coarse nature of the host sediments has obliterated the fine morphological detail of the specimens, at least one suggests evidence of entrainment by a turbidity current. A second shows evidence of detachment of the distal tip of one of its arms. In addition to fossil discoveries from glaciomarine sediments, the volcanic tuffs of the JRIVG represent a new source of fossil data that can be used to interpret the ecology and environment of the Antarctic marine shelf biota during the Neogene.

Alkanes and polycyclic aromatic hydrocarbons were quantified in samples of coastal sediments along Fildes Peninsula, King George Island, South Shetland Islands, Antarctica, during the summers of 2005 and 2007. Quantification was done by using GC-MS and applying the EPA 3550B method. Individual polycyclic aromatic hydrocarbon (PAHs) concentrations were below 14.4 ng g-1 dry wt in 2005 and below 88.7 ng g-1 dry wt in 2007. Alkanes concentrations were higher than those of PAHs and ranged from 8 to 2236 ng g-1 dry wt in 2005 and from 53 to 745 ng g-1 dry wt in 2007. Results of total PAHs and alkanes were integrated along with base administrative and geographic maps in a GIS environment to determine the geographic extent of hydrocarbons detected. The largest concentrations were found in areas near research stations where total n-alkanes suggest petrogenic sources and where some diagnostic ratios suggest the presence of some PAHs produced by pyrogenic processes. Even if concentrations of hydrocarbons are low, they seem to be a result of increases in scientific activities, in the activities of the stable population, in the number of tourists, or a combination of theses factors.

Tintinnid ciliates were present throughout the upper (100m) water column of the ice-edge zone when sampled in autumn 1986 in the Weddell Sea. Biomass ranged from 0.02 μgC1−1 under the sea-ice to 1.3 μgC1−1 in the ice-free water column. Cymatocylis, Codonellopsis, Laackmaniella and a small Salpingella were the most abundant and/or largest biomass contributors. The under ice assemblage was characterized by low biomass and dominated by small species (Salpingella and Codonellopsis); the ice edge stations were dominated by these same taxa but in higher abundances while the open water assemblage was characterized by high biomass and dominated by Cymatocylis, the largest taxa. All taxa exhibited maximum concentrations in the upper 50m of the water column. Both krill and salps grazed upon the Cymatocylis and Codonellopsis without preference in both the ice covered and open water regimes.

We investigated intraspecific geographic variation in buoyancy by obtaining percentage buoyancy (%B) measurements for the Antarctic notothenioid species Pleuragramma antarcticum, Trematomus hansoni, T. bernacchii and Gymnodraco acuticeps from both McMurdo Sound in East Antarctica and the South Shetland Islands in West Antarctica. Mean percentage buoyancies in these species ranged from 0.22–0.52% in the neutrally buoyant P. antarcticum to 3.34–3.67% in the benthic T. bernacchii. Dispersion (1 standard deviation) of percentage buoyancy (%B) values around the mean was ± 0.2–0.5 %B units for the entire sample. Although intraspecific differences in mean percentage buoyancy were statistically significant (P < 0.05) in P. antarcticum and T. hansoni, we consider these differences as normal variation without substantive biological significance. The dispersion in buoyancy measurements during adult life reflects the density of the fish and this may be influenced, in both the short- and long-term, by gut contents, nutritional condition, and reproductive state. Mitigation of the effects of these variables is not biologically realistic because they constitute normal aspects of the daily and yearly life cycles. The results of our measurements of buoyancy are consistent with what is known about the ecology of these four species and this is considered in the discussion.

Enzymatic polymorphism was used to detect variability within Notothenia rossii from two sites on the Kerguelen Plateau and Champsocephalus gunnari from the same sites and the South Orkney Islands. No polymorphism was found in the second species and it was low but not statistically significant in the first. This apparent homogeneity does not substantiate suggestions from other results that the populations can be separated, especially in the case of C. gunnari. Other approaches will be necessary to solve definitively the question of population separation.

At monthly and annual timescales, the zonally asymmetric circulation over the Southern Ocean is dominated by two quasi-stationary anticyclones: a western anticyclone approximately located south of New Zealand, and an eastern anticyclone located over the Drake Passage region. In this research their influence on late 20th century Antarctic sea ice is explored. During early winter, sea ice in the Weddell, Amundsen and Bellingshausen seas is influenced by the location of the east anticyclone. During late winter, the strength and location of the west anticyclone influences sea ice primarily in the Ross and Amundsen seas. The anticyclones have some effect on wind-driven sea ice motion, but the primary mechanism explaining their link to sea ice appears to be meridional atmospheric thermal advection. A western shift in the west anticyclone may be partly responsible for observed increases in ice cover in the Ross Sea over the late 20th century, but there is little evidence in existing data to support a link between the east anticyclone and observed sea ice trends.