To provide data on the degree of contamination of the marine ecosystem isomer-specific concentrations of polychlorinated biphenyls, including planar, mono- and di-ortho congeners, were measured in the Weddell seal, the Adélie penguin, the south polar skua, and in two species of Antarctic fish (Trematomus bernacchii and Chionodraco hamatus) from Terra Nova Bay, Antarctica. The results show a clear relation between PCB concentrations and trophic level, in the order fish < Adélie penguin < Weddell seal. The higher values found in the skua appear to be related to its migration to more contaminated lower latitudes. The data for the various PCB congeners were used to calculate toxic potential in the different animals. The 2,3,7,8-TCDD toxic equivalents of coplanar congeners were estimated by the “toxic equivalent factors” (TEFs) approach. The highest values of TEFs were found in the south polar skua and Weddell seal. Values in the other species were considerably lower.

A cytogenetic study on the bovichtid species Cottoperca gobio from the Magellan Strait and Pseudaphritis urvillii from Tasmania showed both species have a plesiomorphic number of chromosomes (2n=48). However, C.gobio has a more conservative karyotype composed entirely of acrocentric chromosomes (Fundamental Number=48); the presence of two metacentric pairs in P. urvilli (FN=52) makes this species karyologically more derived. The differences in the number of chromosomal arms, and the chromosomal location of the nucleolar organizer regions indicate karyological divergence in the two separating stocks from which C.gobio and P.urvillii originated. During the diversification of this notothenioid family, probably coincident with the fragmentation of Gondwana, the stock that split off with the Australian Plate gave rise to the Tasmanian species and experienced more chromosomal modifications than the stock from which C. gobio is derived. The pattern of constitutive heterochromatin suggests a possible homology between a pair of chromosomes in bovichtids and other notothenioids.

Photosynthetic photon flux density (PPFD), air relative humidity and thallus temperature (TT) were measured in Usnea antarctica over a period of 12 months at a coastal rock on King George Island, South Shetland Islands. TT had an annual amplitude of c. 54 K with the maximum of +27.4°C recorded in December and minimum of −27.3°C in July. Daily maximum TT exceeded 0°C every month except in June and July when they were below −0.4°C and −1.6°C, respectively. Daily minimum temperatures were always below zero. Diel courses of PPFD showed pronounced seasonal differences between summer (more than 2000 μmol m−2s−1) and winter (less than 50 μmol m−2s−1 in July). Daily sum of PPFD was highest (more than 30 mol m−2d−1) in December and lowest (0.1 mol m−2d−1) in July. A photosynthesis model was used to estimate the potential annual primary production from habitat PPFD and TT. The estimated potential annual carbon balance of U. antarctica was 323 mg CO2 g−1 dry weight y−1 assuming that the lichen was always at optimal moisture. The potential carbon balance indicates that primary production is severely limited by low PPFD and subzero TT in the austral winter. Nevertheless, the PPFD and TT would allow metabolic activity during winter but with a negative carbon balance during May–August. Spring and autumnal months are revealed as probably the most important periods for lichen primary production because PPFD exceeds photosynthetic light compensation point during the daytime and ambient moisture conditions frequently favour a positive carbon balance.

Marine sediment cores were obtained from in front of the Müller Ice Shelf in Lallemand Fjord, Antarctic Peninsula in the austral summer of 1990–91. Sedimentological and geochemical data from these cores document a warm period that preceded the advance of the Müller Ice Shelf into Lallemand Fjord. The advance of the ice shelf is inferred from a reduction in the total organic carbon content and an increase in well-sorted, aeolian, sand in cores proximal to the present calving line. This sedimentological change is paralleled by a change in the foraminiferal assemblages within the cores. Advance of the ice shelf is indicated by a shift from assemblages dominated by calcareous benthic and planktonic forms to those dominated by agglutinated forms. A 14C chronology for the cores indicates that the advance of the Müller Ice Shelf took place c. 400 years ago, coincident with glacier advances in other high southern latitude sites during the onset of the Little Ice Age. Ice core evidence, however, documents this period as one of warmer temperatures for the Antarctic Peninsula. We suggest that the ice shelf advance was linked to the exclusion of circumpolar deep water from the fjord. This contributed to increased mass balance of the ice shelf system by preventing the rapid undermelt that is today associated with warm circumpolar deep water within the fjord. We also document the recent retreat of the calving line of the Müller Ice Shelf that is apparently in response to a recent (four decade long) warming trend along the western side of the Antarctic Peninsula.

Studies of glacier margins have suggested that form and structure can be used to infer mass balance condition and stability. This paper examines this idea by investigating the form and structure of the Antarctic ice sheet at two coastal oases in East Anarctica. Two principal forms of the margin of the ice sheet in the Vestfold and Bunger hills that are discussed are ice cliffs and gently-sloping ice margins with an inner moraine. The form of the ice margins in both areas is primarily related to the accumulation of drift snow and superimposed ice and not to mass balance condition. It is concluded that the form and structure of ice margins are ambiguous indicators of mass balance condition and stability and that a change in mass budget is probably neither a sufficient nor a necessary condition for a change in the morphology of ice margins. Although we argue that the form and structure of the ice margins tells us little about stability, interpretation of the Holocene history and geomorphology of the oases suggests that the ice margins have been stable at least throughout the Holocene and that this condition of overall stability continues today.

The lichen and moss collections by G.T. Bowra in Heimefrontfjella in 1963–64 are redetermined. These are the only plant collections made in Heimefrontfjella prior to a Swedish expedition in 1991–92. Taxonomical and nomenclatural improvements have resulted in several changes. A total of 16 lichens and two mosses were found.

Laboratory studies have shown that Antarctic krill (Euphausia superba) shrink if maintained in conditions of low food availability. Recent studies have also demonstrated that E. superba individuals may be shrinking in the field during winter. If krill shrink during the winter, conclusions reached by length-frequency analysis may be unreliable because smaller animals may not necessarily be younger animals. In this study, the correlation between the body-length and the crystalline cone number of the compound eye was examined. Samples collected in the late summer show an apparent linear relationship between crystalline cone number and body-length. From a laboratory population, it appears that when krill shrink the crystalline cone number remains relatively unchanged. If crystalline cone number is little affected by shrinking, then the crystalline cone number may be a more reliable indicator of age than body-length alone. The ratio of crystalline cone number to body-length offers a method for detecting the effect of shrinking in natural populations of krill. On the basis of the crystalline cone number count, it appears from a field collection in early spring that E. superba do shrink during winter.

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).

Rb-Sr ages of Swanson Formation on Edward VII Peninsula, West Antarctica, indicate a late Ordovician age, 421–432 Ma for regional metamorphism. K-Ar ages of 113–440 Ma, reflect a second thermal metamorphism during emplacement of widespread Cretaceous granites. Rb-Sr ages of five monzogranite/syenogranitic plutons of Byrd Coast Granite are in the range 95–105 Ma (initial 87Sr/86Sr ratios 0.710–0.715) and represent stages of crystallization of anorogenic granite (A subtype). These correlate with Byrd Coast Granite (100–110 Ma) farther east in Marie Byrd Land, and with Cretaceous granitoids on the Campbell Plateau and in southern New Zealand. K-Ar mica/hornblende and fission-track apatite/zircon ages indicate that regional cooling began c. 90–100 M.y. ago immediately after granite emplacement. Uplift continued throughout the peninsula during the period 55–100 Ma (late Cretaceous-early Tertiary), associated with regional uplift in the rift-drift stages of Gondwana break-up at the South-west Pacific spreading centre. Apatite fission track ages show that during late Cretaceous-early Tertiary time the peninsula behaved as two blocks. The Alexandra Mountains were exhumed 20 m.y. before the Rockefeller Mountains and are possibly separated by a fault active initially in the mid-Cretaceous or earlier, and later reactivated in the late Cretaceous-early Tertiary. An averaged uplift rate (50–100 Ma) of 0.025 mm yr−1 is characteristic of the inferred intraplate tectonic setting.

Properties of the surface and bottom circulation in the north-west Weddell and south Scotia seas in the region 59–66°S, 36–46°W are examined. The bottom currents have been recorded at different heights from 5–800 m above the seabed, and surface velocities have been obtained from the drift tracks of ARGOS buoys deployed in ice floes. The tidal regime is mixed and the power of motions at inertial frequencies is very variable and most dominant in the Scotia Sea. Flow is influenced by topography, effects of which are seen in eddy features and the damping of inertial motions in some areas. The sea ice motion is shown to be influenced by the bottom topography at very low frequencies whilst tidal periodicities observed in the north-western Weddell Sea are below the level of the noise in the region of the study. In this area the higher frequency ice motion is mainly wind driven with little of the energy being transferred to the underlying deep water.

Seismic reflection surveys were carried out over the Larsen Ice Shelf to examine the extent of the observed sedimentary sequences of the Larsen Basin as suggested by aeromagnetic and gravity data. The surveys were carried out with a small team of six, working from Skidoo motor toboggans and Nansen sledges. Charges of up to 8 kg were fired in hot-water drilled holes up to 9 m deep and 6 sec records made by a 48 channel TI DFS V system with a 4 ms sample interval. By towing a 2.4 km cable behind a Skidoo it was possible to obtain 2.4 km of 24 fold data per day. The reflection data were supplemented by shallow refraction surveys using a 12 channel Nimbus seismograph and by a 12 km expanding spread experiment. The refraction data gave velocities of 1305 ± 20 m s−1 for surface snow and 3154 m s−1 for the top 100 m of shelf ice. The 24 km of reflection data showed high seismic velocities with weak shallow reflectors, characteristics which are quite different from the known basin fill on James Ross Island. It is concluded that the surveys were done outside the basin and that the depth to basement estimates made from the aeromagnetic data do not provide a reliable guide to the extent of the basin.

Continental freshwater lakes of Antarctica are characterized by species-poor biota (Heywood 1977). The plankton is dominated by algae, bacteria and protozoa (Koob & Leister 1972, Parker et al. 1982, Laybourn-Parry et al. 1991). Three species of micro-crustacea have been reported from Eastern Antarctica, the cladoceron Daphniopsis studeri, Ruhe and two copepods, Acanthocyclops mirnyi, Borutsky & Vinogradov, and Boeckella poppei, Mrazek (Borutsky & Vinogradov 1957, Akatova 1964, Bayley & Burton 1993). The origin of D. studeri in lakes of the Vestfold Hills has been documented (Laybourn-Parry & Marchant 1992) and it is generally thought that populations are derived from subantarctic islands and mainland South America. Populations of D. studeri from three freshwater lakes of the Vestfold Hills, have been studied in more detail in a preliminary survey of its occurrence and basic life cycle (Laybourn-Parry & Marchant 1992) during which it was observed that the population consisted entirely of parthenogenic females appearing to produce only subitaneous eggs. Herbert (1981) reported that some Arctic and Antarctic cladocerans were capable of producing ephippial (wintering) eggs asexually. D. studeri also occurs in some of the brackish lakes of the Vestfold Hills with salinities of <4 ppt. These populations were found to possess male individuals (J. Gibson, personal communication 1991) suggesting a sexual cycle and production of resting eggs. There is no evidence of this in the freshwater lakes of the region.

On Hurd Peninsula (Livingston Island) neotectonic features, such as faults, affect the landforms and emerged marine levels. A detailed local study of these features provides information on the recent structural and geomorphological evolution of the area. We suggest that Hurd Peninsula is divided into several tectonic blocks separated by faults. Movement of the faults determines the relative altitude of these blocks and, in consequence, their susceptibility to glacial, periglacial or marine processes. Although some of the tectonic movements reflected in the landforms may have been inherited from former phases of deformation, some of the neotectonic faulting has a maximum lower Miocene age. A new method of correlation of emerged beach levels is suggested and the possibility of analysing the effects of neotectonic deformations from their analysis is discussed. The application of the methods tested here to other areas of the South Shetland archipelago could provide insights into the timing and mechanisms of recent tectonic evolution.

A new xanthid crab, Tumidocarcinus foersteri n. sp. is described from the La Meseta Formation on Seymour Island, Antarctica. The fossils were obtained from the Allomember Submeseta of Late Eocene age. As other representatives of the genus Tumidocarcinus were only known from New Zealand and Australia, this finding provides new insights on the palaeobiogeography of high latitude faunas during the Early Tertiary.

K-Ar whole-rock dating of five samples of quartz-mica schist from the Nordenskjöld Coast, eastern Graham Land, provides the first unequivocal evidence of pre-Triassic (> 249 ± 7 Ma) deposition of a sequence regarded as part of the Trinity Peninsula Group (TPG). A maximum age range of latest Carboniferous (< c. 300 Ma)–Permian for deposition of the Nordenskjöld Coast sequence is indicated, and a polymetamorphic, polydeformational history for the TPG in northern Graham Land. However, the possibility exists that the rocks dated here from the Nordenskjöld Coast are part of a hitherto-unrecognized metamorphic basement unrelated to and older than the mainly Triassic TPG outcrops farther north. The new ages confirm the existence of a previously poorly-defined regional metamorphic event in the Antarctic Peninsula at about 245–250 Ma ago.

Megafloral remains recovered from the Jetty Member and the upper part of the Flagstone Bench Formation, Amery Group include Dicroidium and Pagiophyllum. Dicroidium zuberi and D. crassinervis forma stelznerianum occur with Pteruchus dubius and support a Mid to Late Triassic age. A new species of conifer, Pagiophyllum papillatus, is recognized along with an undetermined conifer pollen cone.

Carlini et al. (1990) reported the presence of Xenarthra (Mammalia) from the Eocene deposits of Seymour Island, Antarctic Peninsula, based on an ungual phalanx from locality RV 8200. The locality, referred to informally as “mammal site” by Woodburne & Zinsmeister (1984), is located at 64°14′21″S, 56°39′44″W at an elevation of 45 m in the middle levels of the shallow marine La Meseta Formation (TELM 5 of Saddler 1988). Carlini et al. (1990) initially identified the phalanx as a megatherioid sloth (Order Tardigrada). Marenssi et al. (1994) revised its identification to ?Tardigrada or ?Vermilingua, by comparison with a primitive myrmecophagid (Order Vermilingua) from the Lower Miocene of Patagonia, whose ungual phalanges are indistinguishable from those of primitive sloths (Carlini et al. 1992). We report a fragmentary tooth of a member of the Tardigrada (Family incertue sedis) confirming the presence of this group in the Eocene of Antarctica.

The poly-deformed Priestley schist (Wilson Terrane) of north Victoria Land, Antarctica ranges in metamorphic grade from lower greenschist facies to upper amphibolite facies. All grades of schist have been affected by structurally controlled retrogressive H2O-CO2 fluids with 45–70 mole % CO2. The fluids have deposited quartz-carbonate veins with pyrite and chlorite or biotite in late stage structures. Veins typically constitute < 1% of the rock mass, but in one greenschist facies area > 10% of the rock is vein. Veins in higher grade schists have been boudinaged after formation, and many have been annealed. Primary fluid inclusions are preserved in veins in biotite zone schists in two localities. At one locality, entrapment of immiscible fluids (water with c. 8 and 45 mole % CO2) occurred during vein formation, at about 280–300°C and 700 ± 200 bars fluid pressure. The aqueous fluid is slightly saline (4 wt % NaCl equivalent). At the other primary fluid inclusion locality, veins were formed from a single phase fluid (c. 70 mole % CO2) at 200–350°C and 1600 ± 500 bars fluid pressure. Both these vein systems are inferred to have formed between 2 and 8 km depth, near the brittle-ductile transition. Retrogressive fluid mobility and vein formation occurred throughout schist in the Priestly metamorphic complex during uplift in the latter part of the Ross Orogeny (c. 490 Ma), following near-isobaric cooling at metamorphic depths.

Müller Ice Shelf (67°15′S, 66°52′W) is situated at the southern end of Lallemand Fjord. It is a small ice shelf (∼80 km2) fed by Brückner and Antevs glaciers, which both flow northward off the central peaks of Arrowsmith Peninsula; the ice shelf contains an ice rise (Humphreys Ice Rise). Data sources have indicated that not only has the ice front retreated since 1947 but also that there have been two advances. This paper describes how these changes were recorded using simple photogrammetric techniques.

A fossil hydrothermal system on Barton Peninsula, King George Island, Antarctica, formed a series of lead-zinc- and pyrite + native sulphur-bearing epithermal quartz ± calcite veins, filling fault-related fractures in hydrothermally altered volcanic rocks of Eocene age. The lead-zinc veins occur within argillic hydrothermal alteration zones, whereas the pyrite + native sulphur veins are found within advanced argillic alteration zones. Fluid inclusion data indicate that the vein formation occurred at temperatures between about 125° and 370°C (sphalerite deposition formed at 123–211°C) from fluids with salinities of 0.5–4.6 wt.% eq. NaCl. Equilibrium thermodynamic interpretation of mineral assemblages indicates that the deposition of native sulphur in the upper and central portions of the hydrothermal system was a result of the mixing of condensates of ascending magmatic gases and meteoric water giving rise to fluids which had lower pH (<3.5) and higher fugacities of oxygen and sulphur than the lead-zinc-depositing fluids at depth. The δ34S values of sulphide minerals from the lead-zinc veins (δ34S = −4.6 to 0.7‰) are much higher than the values of pyrite and native sulphur from the pyrite + native sulphur veins (δ34S = −12.9 to −20.1‰). This indicates that the fluids depositing native sulphur had higher sulphate/H2S ratios under higher fo2 conditions. Sulphur isotope compositions indicate an igneous source of sulphur with a δ34SΣS value near 0‰, probably the Noel Hill Granodiorite. Measured and calculated δ18O and δD values of the epithermal fluids (δ18Owater = −6.0 to 2.7‰, δDwater = −87 to −75‰) indicate that local meteoric water played an important role for formation of lead-zinc and native sulphur-bearing quartz veins.