The Tithonian (Upper Jurassic) methane seep carbonate of the Gateway Pass Limestone Bed (Alexander Island, Antarctica) yields enormous numbers of the minute gastropod mollusc, Hokkaidoconcha hignalli sp. nov. together with an unidentified limpet gastropod and occasional protobranch and lucinid bivalves. This assemblage constitutes one of the most abundant (by means of the specimen number) records of Jurassic chemosynthesis-based communities. The gastropod family Hokkaidoconchidae is extremely common in Cretaceous hydrocarbon seep carbonates from Japan and is known also from Upper Jurassic/Cretaceous hydrocarbon seep carbonates in California. It is an extinct family closely related to modern seep and vent dwelling Provannidae. This is the first confirmed record of this family in the Southern Hemisphere, indicating its surprisingly early and widespread distribution reaching high latitudes.

Meltwater ponds are one of the most widespread aquatic habitats in ice-free areas of continental Antarctica. While most studies of such systems occur during the Antarctic summer, here we report on ice formation and water column attributes in four meltwater ponds on the McMurdo Ice Shelf during autumn, when they went from ice-free to > 80 cm thickness of ice. Ice thickness grew at an average rate of 1.5 cm d-1 in all ponds and as ice formed, salts and gases were excluded. This resulted in conductivity rising from 3–5 to > 60 mS cm-1 and contributed to the ebullition of gases. Incorporation of gas bubbles in the ice resulted in a high albedo and under-ice irradiance declined faster than incident, the former falling below 1 W m-2 (daily average) by early April. After two months of ice formation, only 0–15% of the volume of each pond was still liquid, although this represented 5–35% of the pond sediment area, where much of the biological activity was concentrated. We suggest that the stresses that the freezing process imposes may be as important to structuring the biotic communities as those during the more benign summer growth period.

Antarctic petrels Thalassoica antarctica on Ardery Island, Antarctica (66°S, 110°E), experienced major reductions in breeding success and breeder survival over four seasons between 1984/85 and 1996/97. In 1996 the reason was revealed. A large snowdrift covered part of the study colony on the cliffs. Southern giant petrels Macronectes giganteus, normally lacking access to this area, exploited the snow for soft ‘crash landings”. After landing they waited for the disturbed birds to resettle on their nests and then used surprise to seize and kill a victim. Predation continued into the egg period, and only stopped after the snowdrift had melted. Giant petrels showed no interest in the eggs but, during the panic caused by their activities, South Polar skuas Catharacta maccormicki took the deserted eggs. Antarctic petrel mortality due to predation within the 1996/97 season amounted to 15.4% of experienced breeders, and breeding success was reduced to virtually zero. Weather data from the nearby Casey station over the 1980–96 period showed that a significant increase in precipitation has occurred, in combination with shifts in speed and direction of winds. We conclude that the decreases in breeding success and survival in earlier seasons were also related to increased snowfall and predation. Although similar predation behaviour by giant petrels has not been reported before, we think that it is long established and explains why nesting of the smaller fulmarine petrels is limited to steeper cliffs or sheltered sites. The complexity of the response seems unlikely to be predicted by our present understanding of how climate change affects ecosystems.

This study focused on the ability of the Antarctic bacterium Rhodococcus sp. strain AQ5-14 to survive exposure to and to degrade high concentrations of phenol at 0.5 g l-1. After initial evaluation of phenol-degrading performance, the effects of salinity, pH and temperature on the rate of phenol degradation were examined. The optimum conditions for phenol degradation were pH 7 and 0.4 g l-1 NaCl at a temperature of 25°C (83.90%). An analysis using response surface methodology (RSM) and the Plackett-Burman design identified salinity, pH and temperature as three statistically significant factors influencing phenol degradation. The maximum bacterial growth was observed (optical density at 600 nm = 0.455), with medium conditions of pH 6.5, 22.5°C and 0.47 g l-1 NaCl in the central composite design of the RSM experiments enhancing phenol degradation to 99.10%. A central composite design was then used to examine the interactions among these three variables and to determine their optimal levels. There was excellent agreement (R2 = 0.9785) between experimental and predicted values, with less strong but still good agreement (R2 = 0.8376) between the predicted model values and those obtained experimentally under optimized conditions. Rhodococcus sp. strain AQ5-14 has excellent potential for the bioremediation of phenol.

The Bunger Hills Oasis (66°15'S; 100°45'E), a large ice-free expanse on the coast of East Antarctica, contains many lakes, only a few of which maintain an ice cover all year. To understand the environmental conditions that allow for persistent ice cover we established an automatic meteorological station on White Smoke Lake, a perennially ice-covered lake in contact with the Apfel Glacier. The data were collected from January 1992–July 1993. The mean annual solar flux during this period was 115 W m−2, the mean wind speed 4.6 m S−1, and the mean air temperature −11.2°C. Summer degree-days above freezing (71 °C-days) are similar to regions of the Antarctic (the McMurdo Dry Valleys - 78°45'S; 163°00'E) with thick perennial lake ice but the winter freezing degree days (3987 °C-Days) are much smaller and are closer to regions with seasonal ice covers (e.g. the high Arctic). The Bunger Hills Oasis seems to be in a marginal climatic region for the persistence of thick lake ice. Therefore, the extent of glacier ice contact becomes the controlling factor in maintaining an ice cover all year. We propose that this is either through the heat sink the glacier offers, and/or the positive feedback for ice growth provided by the high albedo of the adjacent glacier.

A coastal ichthyological survey was carried out in Terra Nova Bay, Ross Sea during the Italian Antarctic Expedition 1987/1988. Vacchi et al. (1992) described the composition of the coastal fish community. Stomach content analysis was conducted on Trematomus bernacchii and T. pennellii to evaluate the trophic overlap (Vacchi et al. 1994). During the survey, several specimens of T. newnesi were caught at 92 m depth. This fish is a coastal species widespread in the high-Antarctic Zone and also known from the South Shetland Islands and the South Orkney Islands (DeWitt et al. 1990). Although T. newnesi was found down to 400 m depth (Tiedtke & Kock 1989), it seems more abundant in very shallow inshore waters (Naito & Iwami 1982, Williams 1988). Andriashev (1970) and Williams(1988) stated T. newnesi was a cryopelagic species associated with the underside of the sea-ice. At Signy Island, T. newnesi was described as semipelagic species eating amphipods (Richardson 1975). Eastman & DeVries (1982) consider it to be both a cryopelagic and benthic species in McMurdo Sound. Targett (1981) found that T. newnesi feeds on krill and plankton at the South Orkney Islands. Planktivory has also been indicated at the South Shetland Islands (Casaux et al. 1990).

Data on the response behaviour of seals (crabeater, leopard and Ross) and penguins (Adélie and emperor) to helicopter surveys over the pack ice off East Antarctica are presented. The surveys involved Sikorsky S76 helicopters flying at altitude 130 m and speed 90 knots along straight-line transects. The relative frequency of alert and movement behaviours by seal and penguin groups decreased with distance out to 800 m from the flight path. Penguin groups were more likely to show a movement response than seals at all distances. The perpendicular distances moved relative to the flight path were small (maximum 20 m, mean ≤ 3 m, for both seal and penguin groups) relative to the width of the area searched (800 m), and there was no evidence that response movement resulted in a spiked detection histogram. Observers were more likely to feel confident in identifying seal and penguin species if the animals responded to the helicopter by changing the body posture or moving. In this application of aerial survey, the response behaviour elicited by the passing helicopter was considered to be beneficial from a technical perspective, and the disturbance caused to the surveyed populations negligible from an ethical perspective.

Seven community complexes have been described across sub-Antarctic Marion Island, amongst these fellfield that comprise low plant cover dominated by Azorella selago Hook. f. Azorella is considered a keystone species since it forms nutrient rich environments for microarthropod communities and epiphytic plants. Two distinct growth forms typify Azorella, namely discrete cushions and continuous mats. Whether these continuous mats normally consist of a single large cushion individual, or whether several individual plants merge, interdigitating to form a continuous area, remains unclear. As such, it is important to obtain some measure of Azorella growth dynamics before embarking on phylogeographic studies. Previous genetic studies indicated that several microarthropod species are significantly substructured across Marion Island, but it remains unclear whether similar subdivisions characterize Azorella. We used chloroplast sequence data (trnH-psbA) and amplified fragment length polymorphism (AFLP) to investigate these questions. No sequence variation characterized the trnH-psbA region in Azorella across Marion Island. In contrast, the AFLP results indicated that an A. selago mat comprises multiple individuals. We argue that mats can be formed through at least two processes namely fragmentation, where parts of the cushion plant die off creating open areas for the establishment of different individuals and/or high density of interdigitating individuals merging to form the mat. Fragment data further indicated significant substructure for Azorella across Marion Island (FST = 0.101, P = 0.01) and we attribute this to past vicariance.

Maximum dive depths have been recorded for a number of sea-bird species using simple lightweight capillary gauges (Burger & Wilson 1988). So far these studies have been confined to penguins (Montague 1985, Seddon & van Heezik 1990, Whitehead 1989, Wilson & Wilson 1990, Scolaro & Suburo 1991), alcids (Burger & Simpson 1986, Burger & Powell 1988, Harris et al. 1990, Burger 1991) and cormorants (Burger 1991, Wanless et al. 1991).

Nutrient and major ion concentrations were measured in surface water samples from lakes, ponds and streams at sites 30–320 km south of McMurdo Sound: the Darwin Glacier region (79.7–80.0°S), Pyramid Trough in the southern Dry Valleys (78.2°S), and the McMurdo Ice Shelf ablation zone (77.8–78.4°S). These aquatic environments ranged from dilute meltwaters (conductivity <0.05 mS cm−1) to concentrated brines (>50 mS cm−1). The lowest nitrate concentrations were recorded at the sites closest to the seasonally open waters of the Ross Sea. Much higher values (100–142000mg NO3–Nm−3) were recorded at sites further south. These observations support the hypothesis that NO3 precipitation over Antarctica is of stratospheric rather than coastal marine origin. The nitrogen-rich waters contained chloride and nitrate in the ratio 5.45g Cl:1g N (C.V.=8.4%) which is within the range for Antarctic snow, and indicative of nitrate enrichment by freeze concentration processes. Cyanobacterial mats were conspicuous elements of the biota across the full range of salinities, and were usually dominated by oscilatoriacean species. Nitrogen-fixing cyanobacteria and diatoms were also represented in these benthic microbial communities at the more northern sites, but were absent from all samples from the Darwin Glacier region.

New exposures of fossiliferous sedimentary rocks at Cape Framnes, Jason Peninsula (65°57′S, 60°33′W) are assigned to the Middle–Late Jurassic Latady Formation of the south-eastern Antarctic Peninsula region. A sequence of fine to coarse-grained sandstones of unknown thickness has yielded a molluscan and plant macrofossil assemblage rich in the following elements: perisphinctid ammonites, belemnopseid belemnites, oxytomid, trigoniid and astartid bivalves, and bennettitalean fronds and fructifications. The overwhelming age affinities are with the Kimmeridgian–early Tithonian part of the Latady Formation, as exposed on the Orville and Lassiter coasts. The Cape Framnes sedimentary rocks help to constrain the age of a major sequence of acid volcanic rocks on Jason Peninsula, and show that the Latady Basin was geographically much more extensive than recognized previously. It was the principal depositional centre of Middle–Late Jurassic sedimentation in the Antarctic Peninsula back-arc region and in areal extent may have rivalled the essentially Cretaceous Larsen Basin.

This paper reports on sightings and dispersion of individual southern elephant seals (Mirounga leonina) along the Atlantic and Pacific coasts of South America based on reports of tagged/marked seals from Patagonia and of animals of unknown origin. From 154 sightings, encompassing at least 354 individuals, we found that individuals dispersed to subequatorial latitudes on both sides of the continent, and to more temperate sites, in the Magellanic region of Tierra del Fuego. Nineteen sites were visited by tagged seals from the established colony of Península Valdés (PV, Argentina). PV and the smaller seal population of the Falklands/Malvinas were regularly connected by adults of both sexes. There were more sightings of males than females. No incipient new breeding colonies were found along the Atlantic coast of South America. Some observations coincided with places where elephant seals had been recorded or exploited in the seventeenth and eighteenth centuries. A shortage of suitable habitat for expansion and proximity to predictable food could act as a stabilizing process preventing colonization of new areas from PV. Dispersion data, coherent with population genetics, support a Patagonian elephant seal stock.

Plant megafossils collected from the previously unexplored English Coast of eastern Ellsworth Land have yielded the first Glossopteris leaves from the Antarctic Peninsula tectonic province. Collecting at Erehwon Nunatak recovered numerous spatulate leaves of consistent morphology, most likely pertaining to one natural species, and described here as Glossopteris erehwonensis sp. nov., as well as fragments of Phyllotheca and Equisetum. The large sample size, the predominance of Glossopteris leaves, the low species diversity, and the lack of characteristic Early Permian (Gangamopteris) and Early Triassic (Dicroidium, Lepidopteris, Pleuromeia) taxa suggest a Permian, probably Late Permian, age for the Erehwon Nunatak beds. These rocks are thus significantly older than any other sedimentary rocks known from Palmer Land and Ellsworth Land. A second flora, collected from Henkle Peak, consists exclusively of the remains of Elatocladus planus, a conifer which probably dominated forests in this area during the Jurassic. The plant megafossils support correlation of the sedimentary rocks with those of the Middle–Late Jurassic Latady Formation of south-eastern Antarctic Peninsula and eastern Ellsworth Land.

Recent studies of Falkland Islands seabird diets have found that Gonatus antarticus is a major prey item for a number of penguin species. Rockhopper (Eudyptes chrysocome), gentoo (Pygoscelis papua) and Magellanic (Spheniscus magellanicus) penguins breeding in the Falklands are estimated to consume several thousand million Gonatus per annum, with mean dorsal mantle lengths of 28–42 mm. Aspects of the distribution and growth of the G. antarcticus stock in the vicinity of the Falkland Islands are discussed.

Following the break-up of Gondwana, the drift of Antarctica to its present position and the establishment of the Antarctic Convergence, fish evolution was characterized by adaptation to progressive cooling of the environment. The decrease of erythrocyte number and haemoglobin concentration in the blood of Antarctic teleosts raises several questions concerning the physiology of respiration and the enzymatic role of erythrocytes. Our study of the molecular basis of cold adaptation includes the relationship between molecular structure and biological function of haemoglobins. Species of the suborder Notothenioidei, largely confined within the Convergence, have only one major haemoglobin, which displays the Root effect in oxygen binding; on the other hand, Zoarcidae (a family found at all latitudes) have four or five haemoglobins, only one of which displays the Root effect. In addition, our data indicate that the physiological relevance of erythrocyte-like cells, present in very small number in the blood of haemoglobinless Channichthyidae, may be linked to higher content of enzymes, such as glucose-6-phosphate dehydrogenase, in comparison with erythrocytes of red-blooded fishes.

The nematode communities of Antarctica are considered simple. The few species present are well adapted to the harsh conditions and often endemic to Antarctica. Knowledge of Antarctic terrestrial ecosystems is increasing rapidly, but nematode communities remain to be explored in large parts of Antarctica. In soil samples collected at Byers Peninsula (Antarctic Specially Protected Area No. 126), Livingston Island we recorded 37 nematode taxa but samples showed great variation in richness and abundance. Nematode richness decreased with increasing soil pH, whereas total abundances, and the abundance of several trophic groups, were greatest at intermediate pH (around 6.5–7). Moreover, the community composition was mainly related to pH and less so to soil moisture. Trophic group, and total nematode, rotifer and tardigrade, abundances were generally positively correlated. Byers Peninsula is thus, by maritime Antarctic standards, a nematode biodiversity hotspot, and the presence of several previously unrecorded genera indicates that nematode species richness in maritime Antarctica is probably underestimated. Our results indicate that abiotic factors influence nematode communities with little evidence for biotic interactions. The unexplained heterogeneity in community composition is probably related to variation in microclimate, vegetation, topography and unmeasured soil properties, but may also be contributed to by biological processes.

Ichthyoplankton samples were collected during the November–December 1994 Italian Antarctic Oceanographic Cruise carried out to the western Ross Sea. A midwater trawl (Hamburg Plankton Net) was used to collect samples at 26 stations. Larval and juvenile specimens of 21 species belonging to six families (Artedidraconidae, Bathydraconidae, Channichthyidae, Macrouridae, Nototheniidae and Paralepididae) were caught from surface to 380 m depth. Mean relative abundance of larval fish in the whole area was about 2.7 specimens 1000 m−3 of filtered water. Pleuragramma antarcticum were the most abundant as postlarvae and juveniles. Larval and postlarval specimens of Chionodraco myersi were also abundant and widespread. The high number of Trematomus lepidorhinus (570 larvae) found in a single station off Terra Nova Bay (74°48′75“S, 164°36′90”E) was noteworthy. Our data demonstrate that the species diversity of the larval fish community in the western Ross Sea is much as found elsewhere in the Antarctic and show a greater abundance of fish larvae in inshore than in offshore waters.

Measurements of humidity at a height of 4 m were made at Halley Research Station between 1995 and 1997 using a frost point hygrometer. Relative humidities were usually close to ice saturation, particularly during the winter, but ice supersaturations of up to 20% were frequently measured. Supersaturation with respect to liquid water was rarely observed. During the summer, diurnal variation in temperature drove a daily cycle in relative humidity, although corresponding variations in mixing ratio were comparatively small. It is suggested that the high frequency of ice supersaturations and almost total absence of water supersaturation results from the high abundance of condensation nuclei relative to ice nuclei.

To date, many studies surveying the bacterial communities in lichen thalli from diverse geographical areas have shown that Alphaproteobacteria is the predominant bacterial class in most lichens. In this study, bacterial communities in several Antarctic lichens with different growth form and substrates were analysed. The bacterial community composition in fruticose and foliose lichens, Cladonia, Umbilicaria and Usnea, and crustose lichens, Buelia granulosa, Amandinea coniops and Ochrolechia parella, from King George Island was analysed by pyrosequencing of bacterial 16S rRNA genes. Results showed that Proteobacteria, Acidobacteria, Actinobacteria and Bacteroidetes were predominant phyla. The predominant bacterial class in most of the samples was Alphaproteobacteria. Acetobacteriaceae of the order Rhodospiralles in Alphaproteobacteria was the most abundant bacterial family in Antarctic lichens. The LAR1 lineage of the order Rhizobiales, a putative N-fixer which has been frequently observed in lichens from temperate areas, was detected only from a few samples at low frequency. It is expected that other bacterial taxa are working as N-fixers in Antarctic lichens. From the PCoA analysis of the Fast UniFrac distance matrix, it was proposed that the microbial community structures in Antarctic lichens were affected by host species, growth form and substrates.

Bacterial cultures obtained through selective enrichment of beach sand collected 60 days and one year after treatment of sites in a pilot oil spill trial conducted at Airport Beach, Vestfold Hills, East Antarctica, were examined for the ability to degrade n-alkanes and phenanthrene. The effects of different hydrocarbon mixtures (Special Antarctic Blend [SAB] and BP-Visco), fish oil [orange roughy]) and inoculation of replicate sites with water from Organic Lake (previously shown to contain hydrocarbon-degrading bacteria) on the indigenous microbial population were examined. Of the cultures obtained, those from sites treated with SAB and BP-Visco degraded n-alkanes most consistently and typically to the greatest extent. Two mixed cultures obtained from samples collected at 60 days and two isolates obtained from these cultures extensively degraded phenanthrene. 1-Hydroxy-naphthoic acid formed the major phenanthrene metabolite. Lower levels of salicylic acid, 1-naphthol, 1, 4-naphthaquinone and phenanthrene 9-10 dihydrodiol were detected in extracts of phenanthrene grown cultures. This study shows that under laboratory conditions indigenous Antarctic bacteria can degrade n-alkanes and the more recalcitrant polycyclic aromatic hydrocarbon, phenanthrene. The enrichment of hydrocarbon degrading microorganisms in Antarctic ecosystems exposed to hydrocarbons is relevant for the long term fate hydrocarbon spills in this environment.