bluuebunny/crossref_metadata_2025 huggingface dataset:
A revised Archaean chronology for the Napier Complex, Enderby Land, from SHRIMP ion-microprobe studies
Authors: Harley S.L. , Black L.P.
Published: December 2007

The long and complex Archaean evolution of the Napier Complex of Enderby Land, characterized by high-grade metamorphism and several strong deformations, is reassessed in the light of new SHRIMPU–Pb zircon dating results bearing on the ages of protoliths and possible regional extents of distinct Archaean tectonothermal events. Initial felsic igneous activity occurred over a significant time interval c. 3800 Ma ago. An age of 2980±9 Ma for the emplacement of charnockite at Proclamation Island might date the oldest tectonothermal event to be recognized in the Napier Complex. An ensuing, very-high grade, previously imprecisely dated tectonothermal event occurred at 2837±15 Ma. U–Pb zircon ages ranging from 2456+8/−5 Ma to 2481±4 Ma date a subsequent, protracted high-grade tectonothermal event. Whereas the ~2840 Ma event is of regional importance in the Amundsen Bay-Casey Bay area, it is possible that the ~2980 Ma event was of only moderate grade, minor importance, or even absent, in that part of the Complex. If so, the apparent trend to very-high temperature metamorphism in the Tula and Scott mountains compared with the Napier Mountains may reflect two distinct metamorphic events rather than a simple baric and thermal gradient. The oldest crustal component in the Napier Complex appears to have been of igneous derivation. Zircon populations in paragneisses at Mount Sones are similar to those in the nearby orthogneisses, which therefore may have been basement. Another paragneiss, in the Casey Bay area, yields no zircons older than 2840 Ma, probably indicating that pre-3000 Ma crust, which is now located nearby, was not exposed at the time of sedimentation there. The isotopic data are quite complex, particularly in rocks that experienced postcrystallization metamorphic temperatures of 1000°C or more. It is postulated that this complexity, which was largely the product of migration of radiogenic Pb within the zircon grains in ancient times, and produced local excesses of this element with respect to its parent U, was caused by volume diffusion at these abnormally high regional crustal temperatures.
A theoretical evaluation of mineral stability in Don Juan Pond, Wright Valley, Victoria Land
Authors: Marion G.M.
Published: December 2007

Don Juan Pond, located in the Wright Valley, Victoria Land, is unique for several reasons. It is the most saline of the Antarctic lakes, being a near-saturated CaCl2 solution. As a consequence of this high salinity, Don Juan Pond generally remains unfrozen in winter, even at temperatures below -50°C. Don Juan Pond is the site where antarcticite (CaCl2·6H2O) was first identified forming naturally. The objective of this paper is to demonstrate the utility of a chemical thermodynamic model (FREZCHEM) by developing theoretical stability diagrams for ice, halite (NaCl), hydrohalite (NaCl·2H2O), and antarcticite in Don Juan Pond, using experimental data collected on 34 days between 1961 and 1983. The composition of Don Juan Pond at the calculated eutectic temperature (-51.8°C) was CaCl2 = 3.72 mol kg−1 and NaCl = 0.50 mol kg−1, which is similar but not identical to a pure NaCl–CaCl2–H2O system. The low eutectic temperature and high CaCl2 concentrations of Don Juan Pond account for lack of freezing during winter. The model is compatible with the experimental data, and predicts the formation of ice during rare high water periods, halite, and antarcticite. These solid phases have all been reported from Don Juan Pond. The model also predicts the formation of hydrohalite at subzero temperatures; hydrohalite has never been observed at Don Juan Pond, but this may simply reflect that most sampling was done during the summer when halite is thermodynamically more stable than hydrohalite. The FREZCHEM model may prove useful in elucidating the physicochemical behaviour, the origin of salinity, and the evolution of Antarctic lakes.
Mesoscale distribution and abundance of four pelagic copepod species in Prydz Bay
Authors: Beaumont K.L. , Hosie G.W.
Published: December 2007

Knowledge of copepod abundance and distribution has been limited, particularly in the Indian Ocean sector, as the use of coarse sampling gear has meant that copepods were frequently lost from the catch. This study analyses samples obtained from Prydz Bay using a fine mesh (300 μm) Rectangular Midwater Trawl (RMT1) net during summer 1992–93. Results demonstrate that a net of mesh 4.5 mm used in previous studies underestimates total copepod abundance by a factor of 38. The abundance of the smaller species has been underestimated the most. New estimates of copepod biomass indicate that copepods represent approximately 27% of krill biomass. Copepod and krill distributions are shown to be discrete at 82.4% dissimilarity. Mean temperature accounted for 33.6% of the variation in copepod distribution while two of the species showed a slight correlation with chlorophyll a pigment data. These results highlight the numerical importance of copepods and the species' distributions in the East Antarctic marine ecosystem.
Biodiversity and ecophysiology of bacteria associated with Antarctic sea ice
Authors: Bowman John P. , Brown Mark V. , Nichols David S.
Published: December 2007

A total of 135 bacterial strains were isolated from congelation (land fast) sea ice samples and ice algae biomass samples obtained from the coastal areas of the Vestfold Hills in East Antarctica (68°S, 78°E) during the summers of 1992–95. The sea ice isolates, along with reference strains. were analysed by numerical taxonomy and for DNA base composition in order to determine the biodiversity of sea ice bacteria. From these analyses 22 clusters of strains (phena) were obtained with most phena apparently representing novel bacterial taxa. The sea ice isolates could be categorized into three groups based on their ecophysiology: 1) slightly halophilic, psychrophilic bacteria often possessing fastidious growth requirements and which were predominantly isolated from sea ice algae biomass or from algae-rich ice samples; 2) halotolerant and psychrotolerant bacteria; and 3) non-halophilic bacteria isolated primarily from upper sections of congelation ice and other ice samples with low levcls of algal biomass.
Tag-loss in southern elephant seals, Mirounga leonina, at Marion Island
Authors: Wilkinson I.S. , Bester M.N.
Published: December 2007

Rates of tag-loss are determined for Dalton Jumbo Rototags applied to the hind flippers of 4343 (2208 males, 2135 females) southern elephant seal (Mirounga leonina) pups at Marion Island over an eight year period from 1983–1990 as part of a demographic study of the species. Loss rates were the lowest recorded to date for this species (range 0.0–9.1%). No significant relationship existed between age and rate of tag-loss, neither was there any sex or year related differences in age-specific tag-loss rates. The low rates of loss highlight the value of tagging as a marking technique, and allow for high levels of confidence in the reliability of the population parameters that are derived from the tagging data collected for the Marion Island population.
Central and eastern Bransfield basins (Antarctica) from high-resolution swath-bathymetry data
Authors: Gràcia Eulàlia , Canals Miquel , Farràn Marcel. Lí , Sorribas Jordi , Pallàs Raimon
Published: December 2007

For the first time complete swath bathymetric maps of central and eastern Bransfield basins are presented at a medium scale and detailed morphological descriptions are provided. Bathymetry reveals morphological structures which provide important information about the structure, volcanism, and kinematics of these basins. The central basin is dominated by two roughly orthogonal sets of extensional faults (N065° the main set and N145° the secondary set), displays several discontinuous along-axis large volcanic cones and ridges trending about N059°, and undergoes extension roughly normal to the basin. The structure of the eastern basin has a roughly rhomboidal pattern (fault sets along N053° and N103°), displays four deep troughs and a much smaller amount of volcanism than the central basin, and is affected by extension with a significant sinistral strike-slip component.
A unifying lithostratigraphy of late Cretaceous–early Tertiary fore-arc volcanic sequences on Alexander Island, Antarctica
Authors: McCarron Joe J.
Published: December 2007

Late Cretaceous–early Tertiary subduction-related fore-arc volcanic rocks are exposed in a north–south linear belt along the length of Alexander Island. The age and tectonic setting of these rocks is well understood; they are not considered to represent “normal” arc magmas but were generated in the fore-arc as a result of ridge subduction. Due to their distinct composition and mode of formation, they are no longer considered to be genetically related to the Antarctic Peninsula magmatic arc. They are therefore removed from the Antarctic Peninsula Volcanic Group and placed in a newly defined Alexander Island Volcanic Group. The group is made up of the Monteverdi, Staccato, Walton, Colbert, Elgar and Finlandia formations, which vary widely in lithology, facies and age. The Colbert and Elgar formations are subdivided into nine and three members respectively. Type localities, representative lithologies and age of each of the formations are discussed. The Staccato and Colbert Magmatic complexes are defined to include volcanic and plutonic rocks that are considered to be coeval. The Rouen Intrusive complex combines the plutonic rocks from the Rouen Mountains and Rothschild Island on the basis of age and chemistry.
Review—The CCAMLR Ecosystem Monitoring Programme
Authors: Agnew David J.
Published: December 2007

The Convention on the Conservation of Antarctic Marine Living Resources states as part of its objective the maintenance of ecological relationships and the prevention of irreversible changes to the ecosystem. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has implemented an Ecosystem Monitoring Programme (CEMP) for the Antarctic marine environment to give effect to this requirement. The design phase of the programme took three years. The programme has been fully implemented since 1987 and involves monitoring selected predator, prey and environmental indicators of ecosystem performance. The central aim of the programme is the detection of changes in these indicators and the interpretation as to whether these changes are due to natural events or the harvesting of marine living resources. The core of the programme is the acquisition, centralised storage and analysis of standardised monitoring data combined with a strong emphasis on empirical and modelling based research. This both modifies the monitoring approach in line with changing requirements and creates a sound scientific background against which to test the effects of management options on components of the Antarctic ecosystem. The development of procedures for translating monitoring results into management advice is a critical part of the programme. Management takes the form of the regulation of fishing activities. Since 1987 CEMP has collected data on six bird and seal species at 15 sites around the Antarctic. Up to 14 parameters of predator performance and 10 parameters of prey and environmental performance are collected at each site. The data sets collected by CEMP form an extremely powerful tool for understanding and managing the Antarctic marine ecosystem.
Diving behaviour of the grey-headed albatross
Authors: Huin N. , Prince P.A.
Published: December 2007

Foraging grey-headed albatrosses spent 86% of the night but only 20% of the day sitting on the sea; most diving activity occurred during daylight. During the broad-guard period of nesting, peaks of diving activity occurred at midday and dusk. During the subsequent chick-rearing period, however, diving was mainly at dawn and dusk. Of 485 dives measured, the depth averaged 0.74 m, with maximum depth at 6.5 m. On average grey-headed albatrosses dived 24 times during a five day foraging trip. Dive depths increased towards midday, probably as a function of the birds' visual acuity rather than due to vertical migration of their prey. We estimate that grey-headed albatrosses may obtain 30–45% of their daily food requirements by diving.
The lipid, fatty acid and fatty alcohol composition of the myctophid fish Electrona antarctica: high level of wax esters and food-chain implications
Authors: Phleger Charles F. , Nichols Peter D. , Virtue Patti
Published: December 2007

The myctophid, Electrona antarctica, was collected by trawl from the Elephant Island region of the Antarctic Peninsula, and from East Antarctica near 61°S and 93°W. Total lipid was higher in Elephant Island E. antarctica (whole fish, 466–585 mg g−1 dry weight) than those from Eastern Antarctica (394–459 mg g−1). Wax esters comprised 86.2–90.5% of total lipid in E. antarctica flesh. There were no significant differences between Eastern Antarctica and Elephant Island in total wax ester levels, or in levels of wax esters between different tissues analysed. Oily bones (up to 326 mg g−1 in the neurocranium) characterized E. antarctica from both locations, with wax esters as the major skeletal lipid class (67.0–87.9%, percent of lipid). The wax esters may have a buoyancy role in E. antarctica. The only substantial amount of triacylglycerols (29.4%) were found in the viscera of Elephant Island fish. The principal fatty acids of all fish analysed included the monounsaturated fatty acids 18:1(n-9) and 16:1(n-7), with lower levels of 16:0 and 14:0 saturated acids. Fatty alcohols were dominated by the saturated 16:0 and 14:0 (37.8–47.8%) and the monounsaturated 18:1(n-9) and 18:1(n-7) (38.3–59.2%). The low ratio of 22:1/20:1 alcohols observed for E. antarctica is consistent with a diet of amphipods, copepods and other items low in 22:1 alcohols.
Cenozoic tectonic evolution of the Marguerite Bay area, Antarctic Peninsula, interpreted from geophysical data
Authors: Johnson A.C.
Published: December 2007

Magnetic, gravity and bathymetric data from Marguerite Bay are used to study the relationships between oceanic and continental tectonic evolution in the arc and fore-arc of the Antarctic Peninsula. The data are used to redefine the crustal structure of the Marguerite Bay area, providing evidence for a northward continuation of George VI Sound and the Alexander Island Mesozoic accretionary prism almost to the continental shelf edge. A two-stage model of extension, associated with changes in spreading rates and approaching ridge segments, is proposed to explain the crustal structure and Cenozoic tectonic evolution of the area. The model involves the opening of George VI trough by Tertiary dextral transtension, followed by oblique extension in an area bounded by the Tula and Adelaide fracture zones. This interpretation confirms previous work linking oceanic tectonic processes with continental arc and fore-arc structural development.
Holocene isostasy and late Cenozoic development of landforms including Beaver and Radok Lake basins in the Amery Oasis, Prince Charles Mountains, Antarctica
Authors: Adamson D.A. , Mabin M.C.G. , Luly J.G.
Published: December 2007

Geomorphological observations show no detectable uplift (i.e. falling relative sea level) of Amery Oasis since the establishment of relatively stable sea level during the mid-Holocene. The observations around the basin of Beaver Lake include an absence of raised shoreline features, the presence down to the present tidal limit of in situ ventifacts and residual landforms, the cliffed southern shoreline and adjacent shallow subhorizontal floor of Beaver Lake, and the composition of recent moraines on the basin's north eastern edge. This lack of Holocene uplift is consistent with low uplift rates observed from coastal oases of East Antarctica and suggests minor, rather than major, changes to the Antarctic ice sheet during the most recent Quaternary glacial cycle. The formation of Beaver basin is attributed to late Cenozoic glacial excavation by south flowing ice of the palaeo-Nemesis Glacier, initially eroding when relative sea level was higher than it is today. The basin containing Radok Lake was excavated by the palaeo-Battye Glacier probably when most effective during the numerous long cold periods of the late Cenozoic. The field evidence from landforms and the presence of marine fossil deposits suggests Amery Oasis was not overrun by erosive ice since at least the Pliocene, major ice streams such as Lambert Glacier flowing then, as now, around the oasis.
Distribution, activity and characteristics of the alpine-type glaciers of northern Prince Charles Mountains, East Antarctica
Authors: Krebs Kim A. , Mabin Mark C.G.
Published: December 2007

Alpine-type valley and cirque glaciers occur in many massifs in the northern Prince Charles Mountains. A total of forty-seven glaciers have been investigated using maps and aerial photographs, and in the summer of 1991–92 seventeen of these were examined in the field. The distribution of these glaciers and their present-day snowline line altitudes appear to be influenced by their location with respect to snow-bearing winds, particularly the summer winds that bring moisture from the open waters of Prydz Bay. Moraine morphologies indicate that these glaciers advance and retreat out-of-phase with the larger ice sheet outlet glaciers. During the last glacial maximum the alpine-type glaciers retreated while the ice sheet outlet glaciers showed a minor expansion. This is believed to be due to the alpine-type glaciers being starved of snowfall as the expanded last glacial maximum sea-ice cover around the continent would have removed their maritime moisture sources. Recent contrasts in the behaviour of the alpine glaciers may reflect changes in summer sea ice extent in Prydz Bay.
A metamorphic perspective on the Pan African overprint in the Amery area of Mac. Robertson Land, East Antarctica
Authors: Scrimgeour Ian , Hand Martin
Published: December 2007

The Amery area of Mac. Robertson Land lies between the early Palaeozoic granulite terrain of Prydz Bay and Meso-Neoproterozoic granulites in northern Prince Charles Mountains (nPCM). In contrast to the nPCM which shows an apparently simple near-isobaric history, granulites exposed in the Amery area contain reaction textures suggesting a more complex evolution. Peak-M1 Mesoproterozoic assemblages formed at c. 700 MPa and 800°C and initially underwent a near-isobaric cooling. A subsequent increase in temperature (M2) resulted in the formation of cordierite-spinel assemblages at ~450 MPa and 700°C in metapelite. The timing of M2 is not firmly established, however existing data strongly suggest it is an early Palaeozoic event coeval with tectonism in Prydz Bay to the north-east. Thus the metamorphic evolution of granulites in the Amery area reflects a terrain-scale thermal interference pattern between two unrelated orogenic events. In rocks not recording post-M1 isobaric cooling, the superposition of M2 on M1 assemblages resulted in the formation of M2 cordierite-spinel symplectites at the expense of peak M1 garnet and sillimanite. This texture, commonly interpreted to reflect near-isothermal decompression, has no relevance in terms of a single tectonothermal event in the Amery area.
Age, growth and maturation of the squid Martialia hyadesi (Cephalopoda, Ommastrephidae) in the south-west Atlantic
Authors: Arkhipkin Alexander I. , Silvanovich Natalia V.
Published: December 2007

The statolith microstructure was studied in 142 females (mantle length, ML, ranging from 77–402 mm) and 119 males (72–328 mm ML) of Martialia hyadesi caught on the Patagonian and Falkland shelves and at the Antarctic Polar Frontal Zone between 1989–94. The statolith microstructure dark zone in this species, contains narrower and more numerous growth increments than the dark zones of other ommastrephid squids. Assuming daily production of putative growth increments within statoliths males live up to 12 months, and females live up to 13 months. It is likely that the life cycle lasts c. 1 yr, but immature squids with ages >330–340 d suggest that a part of M. hyadesi populations could have life span >1 yr. Growth in length was best described by the Gompertz function, whereas growth in weight was best described by the logistic function. M. hyadesi is characterized by slow juvenile growth (<100 mm ML), fast growth of immature squids and a sharp decrease in growth rates during maturation. M. hyadesi mature later (at ages >270 d) than other temperate ommastrephids, but maturation is rather rapid (2–3 months). In the south-west Atlantic, M. hyadesi hatch throughout the year.
Grazing by the Antarctic fish Notothenia coriiceps: evidence for selective feeding on macroalgae
Authors: Iken K. , Barrera-Oro E.R. , Quartino M.L. , Casaux R.J. , Brey T.
Published: December 2007

In Potter Cove, King George Island, Antarctica, macroalgae provide a significant food resource for herbivores. The demersal fish Notothenia coriiceps feeds on macroalgae. Eighteen algal species were identified in stomach contents: two chlorophytes, ten rhodophytes and six phaeophytes. Among these the rhodophyte Palmaria decipiens, the phaeophyte Desmarestia menziesii and the chlorophyte Monostroma hariotii comprised the greatest proportions of algal biomass. A food selection study showed four algae to be preferred (P. decipiens, M. hariotii, D. menziesii, Iridaea cordata) and two species to be avoided (Desmarestia anceps and Himantothallus grandifolius) by N. coriiceps. The present investigation indicates that this fish feeds not only intentionally, but also selectively, on macroalgae. Preference for particular algal species is not related to associated epifaunal biomass or to associated amphipod biomass.
Mycosporine-like amino acids in 38 species of subtidal marine organisms from McMurdo Sound, Antarctica
Authors: McClintock J.B. , Karentz D.
Published: December 2007

Mycosporine-like amino acids (MAAs) that absorb UV radiation (310–360 nm) were investigated in 34 species of benthic marine invertebrates (fourteen sponges, two cnidarians, one nemertean, four molluscs, one bryozoan, two arthropods, eight echinoderms and two tunicates), two species of benthic fish and two species of red algae collected during the spring of 1992 from McMurdo Sound. In addition, MAAs were measured in the ripe ovaries, testes and brooded juveniles of four species of echinoderms. While 90% of the species had MAAs in their tissues, both quantitative and qualitative measurements reflected a general lack of UV protectants among these fauna. Eight MAAs were detected among the species examined, but only four of these (mycosporine-glycine, shinorine, porphyra-334 and palythine) occurred in any appreciable number of the species. Palythinol only occurred in the sponge Isodictya erinacea and asterina-330 and palythene only occurred in the red alga Iridaea cordata. MAAs were detected in the ripe ovaries and testes of the sea urchin Sterechinus neumayeri and the ripe ovaries and brooded young of the sea cucumber Cucumaria ferrari. Low levels and abundances of MAAs may reflect a reduced need for UV protectants in marine organisms inhabiting subtidal (>20 m depth) benthic environments that experience seasonal sea-ice cover. Low concentrations of MAAs may also be a function of diet, since the majority of benthic species present in McMurdo Sound are not herbivorous.
Horizontal patchiness in sympagic organisms of the Antarctic fast ice
Authors: Swadling Kerrie M. , Gibson John A.E. , Ritz David A. , Nichols Peter D.
Published: December 2007

Patchiness in the horizontal distribution of sympagic organisms was studied at an Antarctic coastal site during autumn. A hierarchical sampling design (nested ANOVA) was used to assess variation in the biota on scales from metres to kilometres. Metazoan abundance, chlorophyll concentration and salinity were measured in 54 sea ice cores. The metazoan fauna was dominated by nauplii of the copepod Paralabidocera antarctica (6 × 104 to 4 × 105 m−2). Other copepods present included Stephos longipes, Oncaea curvata, Oithona similis, Ctenocalanus citer, and unidentified harpacticoid copepods. Chlorophyll a concentrations were generally much higher than values recorded at other sites at the same time of the year, reaching a maximum of 78 mg m−2. Metazoan abundances did not correlate strongly with chlorophyll or salinity. Significant variability in abundance of P. antarctica and O. similis, and chlorophyll concentration occurred at the scale of kilometres, whereas salinity and other metazoan abundances were not significantly variable at any of the scales examined. Considerable variation was evident at scales of less than one metre.
Trans-nonachlor, octachlorostyrene, mirex and photomirex in Antarctic seabirds
Authors: Brink Nico W. Van Den , Ruiter-Dijkman Elze M. De
Published: December 2007

Octachlorostyrene (OCS) and trans-nonachlor (TNC) were detected in cape petrels (Daption capense) of King George Island, which tallies with their presence in samples of gentoo penguins (Pygoscelis papua) of the Falkland Islands. The detection of TNC in a sample of the Antarctic southern fulmar (Fulmarus glacialoides) implies that the Antarctic region has been contaminated by this compound. Mirex and photomirex were also detected in samples of the cape petrels and southern fulmar, as well as in Adélie penguins (Pygoscelis adeliae) from Hop Island. The ratios of the mirex and photomirex concentrations in the truly Antarctic species from different locations are similar, which suggests that these compounds are diffusely distributed over the continent. The detection of organochlorine pollutants in Antarctic seabirds is an indication that these compounds have a global distribution. Screening of subcutaneous fat of Antarctic seabirds for organochlorines provides an excellent indication of the occurrence of organochlorine pollutants in Antarctica, and as such an ‘early warning’ for the global dispersion of these compounds.
Ten-month observation of the bottom current regime across a sediment drift of the Pacific margin of the Antarctic Peninsula
Authors: Camerlenghi Angelo , Crise A. , Pudsey C.J. , Accerboni E. , Laterza R. , Rebesco M.
Published: December 2007

We present two time series of bottom current and temperature collected 8 m above the seabed on either side of a large sediment drift located on the continental rise of the Pacific margin of the Antarctic Peninsula. The mean current speed is comparable (6.2 cm s−1 and 6.1 cm s−1 respectively), but the mean direction differs by about 121°. The direction of mean flow follows the bathymetric contour, and the maximum speed never exceeds 20 cm s−1 (below the typical benthic storm threshold). The potential temperature is remarkably stable (0.11 ± 0.01°C and 0.13 ± 0.02°C at the two sites). The cross-covariance indicates a significant peak at 20.2 days lag, slightly longer than the travel time of 18.7 days calculated between the two stations following the isobaths (98.4 km) and thus providing evidence for the topographic control on bottom water flow. The observed bottom water flow is consistent with deposition of Holocene hemipelagic sediments of the ‘drift maintenance’ stage. Indicators for palaeoceanographic conditions during glacial periods of the ‘drift maintenance’ stage and the older ‘drift growth’ stage are at present too scarce to understand fully how the past oceanographic conditions influenced the evolution of the drifts.
Jurassic trees at Jason Peninsula, Antarctica
Authors: Valle R.A. del , Lirio J.M. , Lusky J.C. , Morelli J.R. , Nuñez H.J.
Published: December 2007

Jason Peninsula (66°10'S, 61°00'W) is a prominent feature extending some 80 km into the Larsen Ice Shelf from the eastern coast of the Antarctic Peninsula, and consists of widely spaced rock exposures and several ice-domes with elevations up to some 600 m (Fig. 1). The feature was first seen from seaward on 1 December 1893 by Captain C.A. Larsen, who named one of the high summits “Mount Jason” after his ship. Leading the 1902–1904 Swedish Antarctic Expedition, Dr Otto Nordenskjöld observed the area from Borchgrevink Nunatak (66°03'S; 62°30'W) and reported that the summits seen by Larsen were separated from the Antarctic Peninsula. The name “Jason Island” was subsequently adopted for this feature, but in the 1950s researchers belonging to the currently named British Antarctic Survey (BAS) determined Larsen's discovery to be a large peninsula, underlain mainly by calc-alkaline volcanic rocks.
Protecting the Antarctic - the Protocol becomes law
Authors: Walton David W.H.
Published: December 2007

We should all be really pleased both with ourselves and with our governments for the amazingly rapid progress the Protocol on Environmental Protection to the Antarctic Treaty has made. Final ratification by twenty six countries in less than seven years is impressive for an international treaty with such wide obligations.
An account of the Mysidacea (Crustacea, Malacostraca) of the Southern Ocean
Authors: Brandt Angelika , Mühlenhardt-Siegel Ute , Siegel Volker
Published: December 2007

An inventory of Antarctic and Subantarctic mysid fauna is presented, together with a summary of the present state of knowledge of species and their taxonomic diversity, geographic and bathymetric distribution patterns. Fifty nine species of Mysidacea (Crustacea, Peracarida) are now known. Of these, 37 were reported for the Antarctic region and 31 for the Magellan region; six species occur further north in the Southern Ocean, but south of 40°S. 51% of the Antarctic Mysidacea are endemic, and the figure for the Magellan region is 48%. Most of the species live hyperbenthically, but some also occur bathy- or mesopelagically. Mysidetes has the most species in the Southern Ocean, and Eucopia australis is the species with the widest bathymetric distribution (600–6000 m depth). It is concluded that an emergence of species onto the Antarctic shelf in the Neogene was quite unlikely, because none of the mysid species is a true deepsea species, and most species occur on the shelf or at the shelf break. It is more probable that present day species colonized the Southern Ocean via shallower waters. The examples of the distribution of different genera suggest that the Mysidacea of the Southern Ocean probably had various geographical origins.
Seasonal movements and foraging areas of adult southern female elephant seals, Mirounga leonina, from Marion Island
Authors: Jonker F. C. , Bester M. N.
Published: December 2007

Seasonal movements and foraging areas of postbreeding (n = 9) and postmoulting (n = 3) adult southern elephant seal females from Marion Island were studied using Geolocation Time-depth Recorders. Movements were classified into three phases – an outbound transit phase, distant foraging phase, and an inbound transit phase. The longest residence time of postbreeding females during their foraging migrations was in areas at the outer edge of their feeding range (± 1460 km) both to the north and south of the island, largely within inter-frontal zones south of the Antarctic Polar Front (APF) and between the Sub-Tropical Convergence (STC) and the Sub-Antarctic Front (SAF). Postmoulting females travelled further afield (2122–3133 km distant) to the APF, to inter-frontal zones south of the APF (within the pack ice outer edge), as well as to the Antarctic Continental Shelf. This study provides additional information on the putative function of dive types in relation to the movement phases of elephant seal females from Marion Island. The relative frequency of assumed ‘foraging’, ‘exploratory’ and ‘transit’ dive types, as well as the duration and location of the different phases of movement suggest two seasonal foraging strategies. Sea floor topography could possibly cue the transit phases of both postbreeding and postmoulting females from Marion Island.
Soil temperatures and stability of ice-cemented ground in the McMurdo Dry Valleys, Antarctica
Authors: McKay Christopher P. , Mellon Michael T. , Friedmann E. Imre
Published: December 2007

Year-round temperature measurements at 1600 m elevation during 1994 in the Asgard Range Antarctica, indicate that the mean annual frost point of the ice-cemented ground, 25 cm below the surface, is −21.7 ± 0.2°C and the mean annual frost point of the atmosphere is −27.5 ± 1.0°C. The corresponding mean annual temperatures are −24.9°C and −23.3°C. These results imply that there is a net flux of water vapour from the ice to the atmosphere resulting in a recession of the ice-cemented ground by about 0.4–0.6 mm yr1. The level of the ice-cemented permafrost is about 12 cm below the level of dry permafrost. The summer air temperatures would have to increase about 7°C for thawing temperatures to just reach the top of the subsurface ice. Either subsurface ice at this location is evaporating over time or there are sporadic processes that recharge the ice and maintain equilibrium over long timescales.
The use of oxygen microelectrodes to determine the net production by an Antarctic sea ice algal community
Authors: McMinn A. , Ashworth C.
Published: December 2007

Oxygen microelectrodes were used to measure the photosynthetic rates of Antarctic fast ice algal mats. Using the oxygen flux across the diffusive boundary layer below the fast ice at Davis, a productivity range of 0–1.78 mg C m−2 h−1 was measured. This is at the lower end of fast ice productivity estimates and suggests that conventional 14C techniques may overestimate sea ice algal mat productivity. Photosynthetic capacity (P max) approached 0.05 mg C. (mg chl a)−1 h −1. Onset of photosynthesis saturation, E k, was found at c. 14 μmol photons m −2 s −1. The irradiance of photoinhibition onset, E inh, was c. 20 μmol photons m −2 s −1 and the irradiance at the compensation point, E c, was 4 μmol photons m −2 s −1.
The chimera of achievement
Authors: Walton David W.H.
Published: December 2007

Antarctic Science is now in its tenth year with the number of pages increasing, its citation rate increasing and the enthusiasm of its editors undimmed! We are grateful to all our contributors, editorial board members and referees for their support which have made the journal what it is. This is a good time to take stock and consider the future.
Seabird distribution and oceanic features of the Amundsen and southern Bellingshausen seas
Authors: Ainley David G. , Jacobs Stanley S. , Ribic Christine A. , Gaffney Ian
Published: December 2007

We describe the distribution and estimate the abundance of seabirds in the Amundsen and southern Bellingshausen seas, and attempt to identify the mesoscale and larger ocean and ice features that explain the birds' discontinuous occurrence patterns. Our general objective was to assess if ocean fronts, especially near the continental shelf break, enhance feeding opportunities for top trophic-level predators. A variety of subsurface thermohaline fronts occurred on both sides of the shelf break, at shallower depths from west to east, and with warmer and saltier water on their northern sides. Pack ice overlaid some of these fronts, especially in the Amundsen Sea. Seabirds comprised either an ice group in pack ice or in polynyas, or an open-water group in waters north of the pack. In the Amundsen Sea, bird densities were near 0 birds km−2 in waters overlying the continental shelf, an unexplained pattern found previously in the Ross Sea but not repeated in the Bellingshausen Sea (5 birds km−2 over the shelf). Both groups were more abundant (densities 3–9 birds km−2) near the frontal zones, the ice edge and the shelf break. In the Amundsen Sea, the distribution of ice-group species was related statistically to proximity of fronts and the pack-ice edge, thermocline slope, and depth of the chlorophyll maximum; water-group distribution was related to distance to the fronts and sea-surface temperature. In the Bellingshausen Sea, distribution of both groups was related to distance to the fronts. Many thousands of petrels, found roosting during daylight on icebergs situated near the shelf break, escaped standard census techniques and, thus, are likely to have diluted positive correlations of avian occurrence patterns with physical features of the environment. While the emperor penguin was seen in high numbers and can dive deep enough to forage within the subsurface fronts, those ocean and food-web processes that apparently affect increased food availability for surface and shallow-diving foragers in the frontal regions remain unclear.
Dissolved gases in perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica
Authors: Andersen D.T. , Mckay C.P. , Wharton R.A.
Published: December 2007

Measurements of dissolved N2, O2, Ar, CO2, and CH4 were made in perennially ice-covered Lake Hoare. Results confirm previous reports that O2 concentrations in the upper water column exceed atmospheric equilibrium and that N2 and Ar are supersaturated throughout the water column. The mean supersaturation of N2 was found to be 2.0 (±0.37) and Ar was 3.8 (±1.1). The ratios of N2/Ar (20.3 ±3.8), and O2/Ar (22.5 ±4.0) at the ice-water interface are consistent with those previously measured, suggesting that bubble formation is the main process for removing gas from the lake. However, the saturations of N2 and Ar greatly exceed those previously predicted for degassing by bubble formation only at the ice-water interface. The data support the hypothesis that removal of gas by bubbles occurs in the water column to a depth of 11 m in Lake Hoare. CO2 concentration increases from near zero at the ice-water interface to 80–100 times saturation at and below the chemocline at c. 28 m. There is considerable variability in the gas concentrations throughout the water column; samples separated in depth by one metre may vary by more than 50% in gas content. It is likely that this phenomenon results from the lack of turbulent mixing in the water column. Methane (c. 2 μg 1−1) was detected below the chemocline and immediately above the sediment/water interface at a depth of 30 m. Samples from lakes Vanda, Joyce, and Miers, also show supersaturations of O2, N2, and Ar at levels similar to levels found in Lake Hoare.
Diatom assemblages in surface sediments of the Ross Sea: relationship to present oceanographic conditions
Authors: Cunningham Wendy L. , Leventer Amy
Published: December 2007

Fifty four surface sediment samples from the western and central Ross Sea were examined to determine relationships between modern oceanographic conditions and surface sediment diatom assemblages. A centered R mode principal components analysis demonstrates four geographically distinct assemblages. The assemblage just north of the Ross Ice Shelf in the central Ross Sea is most closely associated with Stephanopyxis spp. (a heavily silicified diatom abundant during the Pliocene), and may result from a combination of winnowing/reworking, and modern flux of primarily non-siliceous algae. The algal assemblage in the western part of the central Ross Sea is most closely associated with Thalassiosira gracilis (an open water diatom), and reflects early seasonal pack ice break up during the late spring inception of the Ross Sea polynya. The algal assemblage north of Drygalski Ice Tongue, in the western Ross Sea, is most closely associated with Fragilariopsis curta (a diatom common in stratified ice edge zones), suggesting that water column seeding by species melting out of coastal sea ice is important in this area. The assemblage south of Drygalski Ice Tongue is most closely associated with resting spores of Thalassiosira antarctica (a diatom associated with coastal waters). Although the habitat of T. antarctica requires future research, we speculate that sea ice conditions unique to area B support an autumnal T. antarctica bloom.
Stratigraphy of Antarctic late Cenozoic pectinid-bearing deposits
Authors: Jonkers H.A.
Published: December 2007

Antarctic late Cenozoic pectinid-bearing sedimentary strata are chiefly confined to localities in the northern part of the Antarctic Peninsula, in the McMurdo Sound area, and Marine Plain, East Antarctica. Ages of these deposits range from Oligocene to Holocene. Chlamys-like scallops, which are absent from today's Southern Ocean, thrived in Antarctic waters during both glacial and interglacial episodes, but disappeared during the Late Pliocene. Their extinction is believed to result from the combined effects of increased carbonate solubility, habitat loss and limitations in food availability, associated with major cooling.
The semi-annual oscillation and Antarctic climate. Part 1: influence on near surface temperatures (1957–79)
Authors: Van Den Broeke Michiel R.
Published: December 2007

We studied the influence of the semi-annual oscillation (SAO) on near-surface temperatures in Antarctica, using observations of 27 stations that were operational during (part of) the period 1957–79. For the annual cycle of surface pressure, the second harmonic explains 17–36% of the total variance on the Antarctic Plateau, 36–68% along the East Antarctic coast and almost 80% on the west coast of the Peninsula, and decreases further to the north. As a result of the amplification of the wave-3 structure of the circulation around Antarctica, a significant modification of the seasonal cooling is observed at many stations. The magnitude of this modification is largely determined by the strength of the temperature inversion at the surface: the percentage of the variance explained by the second harmonic of the annual temperature cycle is then largest on the Antarctic Plateau (11–18%), followed by the large ice shelves and coastal East Antarctica (6–12%) and stations at or close to the Peninsula (0–5%). A significant coupling between the half-yearly wave in surface pressure and that in surface temperature is found for coastal East Antarctica, which can be directly explained by the changes in meridional circulation brought about by the SAO. We show that the coupling of Antarctic temperatures to the meridional circulation is not only valid on the seasonal time scale of the SAO, but probably also on daily and interannual time scales. This has important implications for the interpretation of time series of Antarctic temperatures, a problem that will be addressed in part 2 of this paper.
Automated observatories for geospace research in polar regions
Authors: Dudeney J.R. , Kressman R.I. , Rodger A.S.
Published: December 2007

The specification, development and deployment of an automated observatory designed to operate unattended for a year in the extreme climatic conditions of the polar regions is presented. Solar- and wind-powered electric generators are used to charge lead/acid batteries to provide a nominal 100 W of electrical power for operating scientific sensors. The equipment is housed in a highly insulated caboose (3m by 2m by 2m). The temperature in the latter is regulated using a unique thermal control system which utilizes the latent heat of 500 l of water stored in 25-l plastic containers. Data are logged to optical disks for collection once per year. The observatory is designed to be air-deployed using a DHC-6 aircraft. The paper discusses the rationale for designing such automated systems, the operational experience gained from several years of operation, and the application of a network of observatories to solar-terrestrial physics research.
Unravelling the History of Climate Change
Authors: Goodwin Ian D.
Published: December 2007

The spatial configuration of the Antarctic ice sheet has fluctuated widely during the Late Quaternary, primarily in response to climate and sea-level forcings. Ice core time-series have long been used as proxy climate records for the Antarctic ice sheet surface and polar atmosphere, and there has been a major multinational effort to drill ice cores on or near the summit of ice domes to retrieve the longest possible records. The annual layering of ice accumulation has afforded high resolution proxy climate records on annual to decadal intervals, spanning a few hundred to hundreds of thousands of years. These time-series have also detailed the changes in the ice sheet surface elevation and dynamics, particularly since the transition from glacial to Holocene climate. However, ice sheet sensitivity to external forcings and the associated fluctuations in ice volume are probably best researched around the ice sheet's margins. The sedimentary record in these circumAntarctic margins holds the key to our unravelling of past and future responses of the Antarctic ice sheet and circumpolar oceans to climate and environmental change, including: fluctuations in ice volume; the distribution of ice shelves; the production of Antarctic bottom water; the variability in the fast ice and pack ice characteristics; biogeochemical cycling and marine productivity; and the evolutionary response of marine and terrestrial species and ecosystems.
Introduction
Authors: Goodwin Ian D. , Pudsey Carol J.
Published: December 2007

This issue contains a group of papers selected from those presented at the 1st workshop of the SCAR-GLOCHANT and IGBP-PAGES cosponsored programme on the Late Quaternary Sedimentary Record of the Antarctic Ice Margin Evolution (ANTIME), held in Hobart, 6-1 1 July 1997. ANTIME is focused on the circurn Antarctic reconstruction of palaeoclimate, palaeoenvironment, and ice sheet palaeogeography throughout the last glacial cycle. There were 65 participants from Australia, USA, UK, Italy, Spain, Japan, Sweden, Germany and Russia at the workshop. The participants included representatives of PAGES, IMAGES, and INQUA. The workshop included three scientific sessions on:

Extent, timing and regional differences during Glacial Stage 2 (10–30 kyr BP) in Antarctica, from the terrestrial and marine records;

Climatic, environmental and glacial events during the Holocene;

Late Quaternary geochronological problems in Antarctica.
Abandoned penguin colonies and environmental change in the Palmer Station area, Anvers Island, Antarctic Peninsula
Authors: Emslie Steven D. , Fraser William , Smith Raymond C. , Walker William
Published: December 2007

Six abandoned colonies of Adélie penguin (Pygoscelis adeliae) were excavated near Palmer Station, Anvers Island, Antarctic Peninsula, to investigate the occupation history of this species. Sediments from each site yielded abundant fish bones and otoliths and squid beaks that represent prey remains deposited by penguins during the nesting period. Radiocarbon analyses indicate that colony occupation began prior to the Little Ice Age (LIA; 1500–1850 AD), with the oldest site dating to 644 yrs before present (BP; average reservoir-corrected date with Is range, 603–679 yr BP). Food remains indicate that the non-euphausiid prey of penguins consisted primarily of a mesopelagic squid (Psychroteuthis glacialis) and two species of fish (Pleuragramma antarcticun and Electrona antarctica). The relative abundance of the first two prey taxa varied significantly among six sites (X2>34.6; df = 10; P <0.001) with colonies dating prior to the LIA having greater representation of squid, and less of silverfish, than those occupied during the LIA. Data from control excavations at three modern colonies indicate a diet similar to that of the pre-LIA sites. These results suggest that Adélie penguins may have changed their diet in response to warming and cooling cycles in the past. In addition, only Adélie penguins are known to have nested in the Palmer Station area prior to the l950s; gentoo (Pygoscelis papua) and chinstrap (P. antarctica) penguins now breeding in this region have expanded their ranges southward in the Peninsula within the past 50 yrs, in correlation with pronounced regional warming.