In the austral summer of 1991–92, 120 sample plots were established along 11 transects at various distances from the Swedish research stations Wasa and Svea in Dronning Maud Land, Antarctica. These plots were re-examined in 2001–02 to evaluate overall changes and possible local impact from human activities around the research stations on the terrestrial vegetation, formed by lichens and mosses. The results showed high consistencies over the ten years, but nevertheless suggest a slight overall increase in both lichen species density and abundance, measured as the number of lichen records. We did not find evidence for any severe human impact on the lichens and mosses around the research stations. However, sample plots located close to the Svea station had been affected by station maintenance, which has caused local decline of lichen species such as Umbilicaria decussata. In contrast to the overall consistency and slight increase in lichens we found a decline of Rhizoplaca melanophthalma.

The Ross seal (Ommatophoca rossii) is the least studied of the Antarctic ice-breeding phocids. In particular, estimating the population status of the Ross seal has proved extremely difficult. The Protocol on Environmental Protection to the Antarctic Treaty currently designates the Ross seal as a ‘Specially Protected Species’, contrasting with the IUCN's classification of ‘Least Concern’. As part of a review of the Ross seal's classification under the Protocol, a survey was undertaken in 1999/2000 to estimate the status of the Ross seal population in the pack ice off East Antarctica between 64–150°E. Shipboard and aerial sighting surveys were carried out along 9476 km of transect to estimate the density of Ross seals hauled out on the ice, and satellite dive recorders deployed on a sample of Ross seals to estimate the proportion of time spent on the ice. The survey design and analysis addressed the many sources of uncertainty in estimating the abundance of this species in an effort to provide a range of best and plausible estimates. Best estimates of abundance in the survey region ranged from 41 300–55 900 seals. Limits on plausible estimates ranged from 20 500 (lower 2.5 percentile) to 226 600 (upper 97.5 percentile).

This paper presents horizontal and seasonal differences in the concentrations of nitrogen and phosphorus in the surface waters of Admiralty Bay. The average annual concentrations of total nitrogen and total phosphorus were found to be 1.054 and 0.129 mg dm-3 respectively. Organic nitrogen constituted 59% of total nitrogen on average, while N-NO3- was substantially higher than N-NH4+ (0.362 and 0.062 mgN dm-3, respectively). Organic phosphorus constituted 34% of total phosphorus on average, and the mean annual concentration of reactive phosphorus was 0.085 mgP dm-3. The observed concentrations of N and P were higher in the nearshore area and lower in the central part of the Admiralty Bay basin. In explaining this account was taken of surface runoff into the bay, the decay of marine macroalgae in the tidal area and the excretion of N and P by marine animals. The concentrations of total nitrogen and total phosphorus in freshwater streams varied from 0.528–5.698 mgN dm-3 and from 0.088–1.709 mgP dm-3. In laboratory experiments, 24-hour loads of total nitrogen and total phosphorus released from the remains of macroalgae into the waters of the bay were estimated at about 6.2 tN and 10.3 tP, while the approximate quantities excreted by macrozoobenthos were 482 kgN and 48 kgP. The availability of N-NH4+ was seen to be greater in the waters of the bay than has been reported for open water in this part of the ocean and water from the Bransfield Strait had a diluting effect on the concentrations of nitrogen and phosphorus in the bay. The role of the wind in carrying mineral salts from waters of the Bay to the inland environment was also discussed.

Several studies have been carried out during the last fifteen years on reproduction, population dynamics and diet of the Antarctic shag, Phalacrocorax bransfieldensis Murphy, at different localities in the South Shetland Islands (reviewed in Casaux & Barrera-Oro 2006). In both the colonies studied and in other colonies counted we observed that the number of breeding pairs was steadily decreasing (Casaux & Barrera-Oro 2006). Casaux & Baroni (2002) had earlier suggested that such a decreasing trend might be related, at least partially, to a marked decrease in the inshore populations of two fish prey species, the marbled notothen Notothenia rossii Richardson and the humphead notothen Gobionotothen gibberifrons Lönnberg (Barrera-Oro et al. 2000), which had been studied over a period of 19 years in coastal waters of the South Shetland Islands. Exactly how a reduction in prey availability affects the shag populations (e.g. migration of breeders to other colonies in the area or to new breeding areas, a decrease in the rate of recruitment, an increase in adult mortality, variation in the age at first breeding, etc) is not clear. To investigate this, we started a banding programme at Nelson Island, South Shetland Islands. We postulated that the processes might operate with different intensities on individuals of different sexes, so all individuals in each population studied needed to be sexed. This posed problems for chicks which have monomorphic plumage and no differences in vocalisations (Casaux & Baroni 2000), so that the normal methods for sexing in the field would not work. As most of the external morphological characters in the chicks of Antarctic shags have stabilized by 45–50 days old (Casaux 1998), Casaux & Baroni (2000) had suggested that the use of discriminant functions originally developed for adults could be an appropriate method to sex chicks more than 50 days old.

Eight taxa of marine invertebrates, including two new bivalve species, are described from the Low Head Member of the Polonez Cove Formation (latest early Oligocene) cropping out in the Vauréal Peak area, King George Island, West Antarctica. The fossil assemblage includes representatives of Brachiopoda (genera Neothyris sp. and Liothyrella sp.), Bivalvia (Adamussium auristriatum sp. nov., ?Adamussium cf. A. alanbeui Jonkers, and Limatula (Antarctolima) ferraziana sp. nov.), Bryozoa, Polychaeta (serpulid tubes) and Echinodermata. Specimens occur in debris flows deposits of the Low Head Member, as part of a fan delta setting in a high energy, shallow marine environment. Liothyrella sp., Adamussium auristriatum sp. nov. and Limatula ferraziana sp. nov. are among the oldest records for these genera in King George Island. In spite of their restrict number and diversification, bivalves and brachiopods from this study display an overall dispersal pattern that roughly fits in the clockwise circulation of marine currents around Antarctica accomplished in two steps. The first followed the opening of the Tasmanian Gateway at the Eocene/Oligocene boundary, along the eastern margin of Antarctica, and the second took place in post-Palaeogene time, following the Drake Passage opening between Antarctic Peninsula and South America, along the western margin of Antarctica.

The clay mineralogical composition of a 552 cm long sediment core from Lake Terrasovoje in Amery Oasis, East Antarctica, was analysed and compared with that in surface sediments from other locations in the vicinity. The lower part of the sediment core is formed by sub- and proglacial sediments with a dominance of smectite and illite, and lower amounts of kaolinite and chlorite. The upper part of the core is deposited after 12 500 cal yr bp and mainly composed of illite and kaolinite, with low amounts of smectite and chlorite, such as found in samples from rock outcrops and covering sediments throughout Amery Oasis. The clay composition in the lower section of core Lz1005 suggest that the basin of Lake Terrasovoje was filled by a 150–200 m thickened Nemesis Glacier prior to 12 500 cal yr bp rather than by local ice caps.

Palaeostress inferred from brittle mesostructures in Seymour (Marambio) Island indicates a Cenozoic to Recent origin for an extensional stress field, with only local compressional stress states. Minimum horizontal stress (σ3) orientations are scattered about two main NE–SW and NW–SE modes suggesting that two stress sources have been responsible for the dominant minimum horizontal stress directions in the north-western Weddell Sea. Extensional structures within a broad-scale compressional stress field can be linked to both the decrease in relative stress magnitudes from active margins to intraplate regions and the rifting processes that occurred in the northern Weddell Sea. Stress states with NW–SE trending σ3 are compatible with back-arc extension along the eastern Antarctic Peninsula. We interpret this as due to the opening of the Larsen Basin during upper Cretaceous to Eocene and to the spreading, from Pliocene to present, of the Bransfield Basin (western Antarctic Peninsula), both due to former Phoenix Plate subduction under the Antarctic Plate. NE–SW σ3 orientations could be expressions of continental fragmentation of the northern Antarctic Peninsula controlling eastwards drifting of the South Orkney microcontinent and other submerged continental blocks of the southern Scotia Sea.

The Bransfield Strait, located between the South Shetland Islands and the north-western end of the Antarctic Peninsula, is a back-arc basin transitional between rifting and spreading. We compiled a geomorphological structural map of the Bransfield Basin combining published data and the interpretation of bathymetric images. Several analogue experiments reproducing the interaction between the Scotia, Antarctic, and Phoenix plates were carried out. The fault configuration observed in the geomorphological structural map was well reproduced by one of these analogue models. The results suggest the establishment of a transpressional regime to the west of the southern segment of the Shackleton Fracture Zone and a transtensional regime to the south-west of the South Scotia Ridge by at least c. 7 Ma. A probable mechanism for the opening of the Bransfield Basin requires two processes: 1) Significant transtensional effects in the Bransfield Basin caused by the configuration and drift vector of the Scotia Plate after the activity of the West Scotia Ridge ceased at c. 7 Ma. 2) Roll-back of the Phoenix Plate under the South Shetland Islands after cessation of spreading activity of the Phoenix Ridge at 3.3 ± 0.2 Ma, causing the north-westward migration of the South Shetland Trench.

Cosmogenic 10Be and 26Al measurements from bedrock exposures in East Antarctica provide indications of how long the rock surface has been free from glacial cover. Samples from the crests of Zakharoff Ridge and Mount Harding, two typical nunataks in the Grove Mountains, show minimum 10Be ages of 2.00 ± 0.22 and 2.30 ± 0.26 Ma, respectively. These ages suggest that the crests were above the ice sheet at least since the Plio–Pleistocene boundary. Adopting a ‘reasonable’ erosion rate of 5–10 cm Ma-1 increases the exposure ages of these two samples to extend into the mid-Pliocene. The bedrock exposure ages steadily decrease with decreasing elevation on the two nunataks, which indicates ~200 m decrease of the ice sheet in the Grove Mountains since mid-Pliocene time. Seven higher elevation samples exhibit a simple exposure history, which indicates that the ice sheet in the Grove Mountains decreased only ~100 m over a period as long as 1–2 Ma. This suggests that the East Antarctic Ice Sheet (EAIS) was relatively stable during the Pliocene warm interval. Five lower elevation samples suggest a complex exposure history, and indicate that the maximum subsequent increase of the EAIS was only 100 m higher than the present ice surface. Considering the uncertainties, their total initial exposure and subsequent burial time could be later than mid-Pliocene, which may not conflict with the stable mid-Pliocene scenario.