bluuebunny/crossref_metadata_2025 huggingface dataset:
Toward ionospheric tomography in Antarctica: first steps and comparison with dynasonde observations
Authors: Heaton J.A.T. , Jones G.O.L. , Kersley L.
Published: December 2007

Total electron content (TEC) measurements obtained at two Antarctic stations over nine months beginning early in 1994 have been analysed as a first step to performing ionospheric tomography. Two receiving systems were deployed at the Faraday and Halley research stations operated by the British Antarctic Survey to monitor signals from a random selection of passes of satellites in the Navy Navigational Satellite System. The resultant measurements of total electron content have been inverted and combined with ionosonde measurements of true height and foF2 to yield two-dimensional contour maps of ionospheric electron density. In spite of the poor geometry of the observations, some 130 satellite passes were found to be suitable for reconstruction using the techniques developed for ionospheric tomography. The contour maps of plasma density have been compared with independent observations of the vertical electron density profile measured by the dynasonde ionospheric sounder located at Halley. An example is presented of a deep trough investigated by the technique, illustrating the potential of the tomographic method for study of an extended spatial region of the ionosphere over inhospitable terrain.
Relationships between surface sediment diatom assemblages and water chemistry gradients in saline lakes of the Vestfold Hills, Antarctica
Authors: Roberts D. , McMinn A.
Published: December 2007

The relationship between surface sediment diatom assemblages and measured limnological variables in 33 coastal Antarctic lakes was examined by constructing a diatom-water chemistry dataset. Canonical correspondence analysis revealed that salinity and silicate each explain significant amounts of variation in the distribution and abundance of the surface sediment diatom taxa. Salinity has the strongest influence, revealing its value for limnological inference models in this coastal Antarctic region.
An assessment of the role of the marginal ice zone in the carbon cycle of the Southern Ocean
Authors: Savidge G. , Priddle J. , Gilpin L.C. , Bathmann U. , Murphy E.J. , Owens N.J.P. , Pollard R.T. , Turner D.R. , Veth C. , Boyd P.
Published: December 2007

The dense phytoplankton blooms observed in earlier studies in the Southern Ocean Marginal Ice Zone (MIZ) may not be representative of all regions, so that some previous assessments of the overall importance of this system in total primary production may have been overestimated. Recent observations have shown that increased phytoplankton production may not always be associated with the retreating ice-edge, due to the unpredictability of meltwater-induced stability. Complex interactions between the MIZ and hydrographic fronts have also been indicated. A range of simple simulations, based on biomass inventories for the major biogeochemical systems in the Southern Ocean, show that the greater part of chlorophyll biomass is located in the extensive regions between the major fronts. Consideration of the fronts and the MIZ only, which we surmize may be the principal sites of export production, indicates that the MIZ is clearly the most important single feature. Even if the occurrence of MIZ blooms in the simulations is reduced dramatically, such blooms still appear to make a substantial contribution to production and, by implication, carbon export.
Freshwater diatom communities of the Strømness Bay area, South Georgia
Authors: van de Vijver Bart , Beyens Louis
Published: December 2007

Modern diatom samples were collected from 43 sites across the Strømness Bay area of South Georgia. From 115 taxa belonging to 22 six diatom assemblages were distinguished. A CCA-analysis indicated that the assemblages are linked to pH and conductivity ranges, and habitat structure. The Eunotia paludosa var. paludosa - Eunotia subarcuatoides assemblage occurs in small acid water bodies. Samples of the Fragilaria germainii - Pinnularia aff. anglica assemblage are found in pools with a relatively high conductivity. The Fragilaria neoproducta assemblage and the Achnanthes subatomoides - Navicula vitabunda assemblage are mainly found in larger pools and lakes. This relationship between the assemblages and pH was comparable with results found in the testate amoebae fauna of South Georgia.
Medium-scale heat fluxes across the Antarctic Circumpolar Current in the Drake Passage and western Scotia Sea
Authors: Piola Alberto R. , Grasselli Monica B.
Published: December 2007

Closely spaced continuous temperature profiles from expendable bathythermographs launched along two sections across the Drake Passage and western Scotia Sea in the summer 1981–1982 are used to examine the vertical medium-scale (∼10–100 m) temperature fine structure. The large-scale temperature structure across the frontal regimes characteristic of the Antarctic Circumpolar Current and the cross-frontal structure of the upper ocean are discussed. In the Drake Passage the heat content drops about 0.5 × 102 Kcal cm−2 (2 × 109 J m−2) across the Subantarctic Zone and 0.9 × 102 Kcal cm−2 (3.6 − 109 J m−2) across the Polar Front. In the Scotia Sea the heat content changes across the front are not as prominent. The statistical model of Joyce (1977) is used to quantify the heat fluxes across the fronts produced by the medium-scale temperature interleaving. In the Drake Passage the estimated heat flux is 0.32 × 10−3 °C m s−1 (1.3 × 103 W m−2) across the Subantarctic Front and 0.46 × 10−3 °C m s−1 (1.9 × 103 W m−2) across the Polar Front. In the Scotia Sea the estimated heat flux is larger in the Polar Front reaching 0.71 × 10−3 °C m s−1 (2.9 × 103 W m−2). The medium-scale fine structure heat fluxes are about 10% of the existing estimates of the mesoscale eddy heat fluxes and comparable to heat fluxes associated with the meridional flow of deep and bottom waters across the Antarctic Circumpolar Current.
Hydrographic and climatic changes influencing the proglacial Druzhby drainage system, Vestfold Hills, Antarctica
Authors: Bronge Christian
Published: December 2007

Freshwater drainage systems, fed by melting of nearby inland ice and perennial snowdrifts, exist in the south-eastern part of arid, ice-free, coastal Vestfold Hills. Most important is the complex Druzhby system. Intriguing questions arise about the conditions controlling its seasonal development and about the consequences of possible changes of those conditions. A water-balance was calculated for 1990–91. The system went through four seasonal phases of which only one displayed a fully developed external drainage. Evidently, the relative duration of those phases can vary considerably from one year to another. The system depends critically on the water supply from ice-dammed Chelnok Lake, which could readily be drained by a minor retreat of Sørsdal Glacier. Exposed to excessive evaporation, the large Crooked Lake would then become internally drained and reach a new equilibrium in ∼830 years. A Crooked Lake sediment core can be interpreted as suggesting this occurred during the Holocene. The idea, inferred from striae, of a late Holocene Chelnok Glaciation reaching the northern shores of Crooked Lake is questioned. Instead, it is suggested that the Chelnok striae originate from local basal melting of the ice sheet draining southward into a deglaciated Sørsdal trough. At present, runoff is determined by opposing short and long-term climatic influences.
The Hanson Formation: a new stratigraphical unit in the Transantarctic Mountains, Antarctica
Authors: Elliot D.H.
Published: December 2007

The stratigraphy of the upper part of the Upper Palaeozoic–Lower Mesozoic Victoria Group in the central Transantarctic Mountains is reviewed. Marked lithologic contrasts exist in the Falla Formation between the lower volcanic-poor part and the upper volcaniclastic part. The name Falla Formation is here restricted to the lower volcanic-poor part of the sequence making it the youngest formation in the Victoria Group. The upper volcaniclastic part, a tuffaceous sequence, is named the Hanson Formation.
A mid to late Holocene readvance of the Law Dome ice margin, Budd Coast, East Antarctica
Authors: Goodwin Ian D.
Published: December 2007

Glacial geological studies on the Windmill Islands and along the Budd Coast at the margin of the Law Dome, East Antarctica, indicate that the glacial extent of Law Dome has fluctuated during the Holocene. The morphology and structural geology of the present ice margin and Løken Moraines indicate that Law Dome has readvanced over part of the Windmill Islands since the culmination of the post-glacial retreat. Sedimentological and geochemical analyses show that Løken Moraines comprise reworked proglacial and coastal marine sediments and ice, which supports the morphological and structural evidence for a readvance. A chronology for the readvance is produced from relative lichenometry of Løken Moraines and coastal nunataks in conjunction with 14C radiocarbon dates from the proglacial and coastal zones. The combined glaciological and geological evidence suggests that the readvance occurred after c. 4000 yr BP in response to a positive mass balance on Law Dome during the Holocene.
Give a dog a bad name
Authors: Thomson Michael R.A.
Published: December 2007

Does Antarctic research have a bad name? The short answer in some quarters is, ‘Yes’. But why should this be so? Antarctica is an exciting and stimulating place to work and, whatever one's field of science, because of the continent's present-day isolated position, its massive ice cover and its previous key location within the ancient Gondwana supercontinent, it holds many important clues and answers to questions about our planet and its environment. Yet, those of us who are required to submit our science to peer review are sometimes perplexed by incomprehensible and unreasonably negative comments that come from outside. Are these non-Antarctic scientists just jealous, or do they have a point?
Chemistry of streams of Signy Island, maritime Antarctic: sources of major ions
Authors: Caulkett A.P. , Ellis-Evans J.C.
Published: December 2007

A general study of the streams of Signy Island, South Orkney Islands, was undertaken to identify the effects of catchment, distance from source, and time on concentrations of dissolved ions. In the majority of cases catchment did not affect the chemistry of streams, although marine-derived ions were affected by distance from the sea. Na+, K+, Mg2+, Ca2+, Cl− and NH4+were derived from the thawing of the winter snowpack. NO3− was derived from areas of permanent ice. SiO44−, Ca2+, Mg2+ and CO2−3 were derived from crustal weathering. Although PO43− was also derived from crustal weathering, it was released as a pulse related to the thawing of the soil.
Biology and phenotypic plasticity of the Antarctic nototheniid fish Trematomus newnesi in McMurdo Sound
Authors: Eastman Joseph T. , Devries Arthur L.
Published: December 2007

Trematomus newnesi inhabited inshore (<20 m) subzero waters in McMurdo Sound where it fed in the water column on Euphausia crystallorophias and fishes. This sample included the largest reported specimens of this species. The length–weight relationship was Weight = 3.17 × 10−6 (Standard Length)3.34, n = 67, r2 = 0.95. The population was phenotypically plastic, with two distinct morphs easily separated by visual inspection – the typical morph and a large mouth/broad headed morph comprising 28% of the sample. The large mouth morph had a wider and blunter head, longer upper jaw, wider gape, more heavily ossified jaws and darker colouration. To document this morphology, four views of the head are illustrated. Inference from morphology and measurements suggested that the large mouth morph was more benthic than the typical semipelagic morph. Museum specimens from Cape Adare confirmed the presence of the large mouth morph 700 km north of McMurdo Sound. This is the first clear example of phenotypic plasticity in any species of marine fish and its discovery extends the bounds of the nototheniid adaptive radiation to the population level. This finding suggests ecological and evolutionary parallels between the inshore waters of the high Antarctic shelf and the low diversity ichthyofaunas of Arctic, boreal and some temperate lakes. Although there is no data on genetic diversification, an alternate interpretation of the phenotypic plasticity is that the large mouth morph is a cryptic or sibling species.
Morphological effects on the water balance of Antarctic foliose and fruticose lichens
Authors: Huiskes A.H.L. , Gremmen N.J.M. , Francke J.W.
Published: December 2007

Uptake and loss of water by six lichen species from the Argentine Islands, Antarctic Peninsula, were studied in their natural habitat and in laboratory studies. Under field conditions, during a period of rain, uptake of moisture ranged from 15% d w h−1 for Usnea antarctica to almost 90% for Mastodia tesselata. Loss rates after the rain ceased were lower than the uptake rates and ranged from 8.5% d w.h−1 in Umbilicaria decussata to 38.8% in M. tesselata. A comparison of thalli of M. tesselata from the shoreline with thalli collected further inland showed significant differences in maximum water content and in rates of water loss and uptake between thalli from these sites, which could be ascribed to the presence of salt in the thalli of M. tesselata from the shore. Thallus samples of Usnea antarctica collected from an exposed site showed lower uptake rates and higher loss rates of water than samples collected from a more sheltered site. Under laboratory conditions the maximum moisture content ranged from 67% in Usnea antarctica to 391% in M. tesselata. Exposed to an atmosphere of c. 40% relative humidity and c. 15°C, lichen thalli lost their water during the first hour of the experiment at rates ranging from 34% of the maximum moisture content in Umbilicaria propagulifera to 70% in U. decussata. Rates of water loss diminished with time, and after 4–6 hours equilibrium was reached, with water contents of 14–16% of thallus dry weight. The microclimate is the driving force for the thallus water regime. Specific differences in rates of water loss and water uptake depend on the morphology and anatomy of the lichen thalli. The results of the laboratory experiments agree with those from the field study. However, local differences in microclimatic or other environmental factors can be responsible for significant differences in the water regime of thalli of the same species, a result which can only be obtained from field studies.
First Pliocene decapod crustacean (Malacostraca: Palinuridae) from the Antarctic
Authors: Feldmann Rodney M. , Quilty Patrick G.
Published: December 2007

A single specimen of palinurid lobster, possibly Linuparus, from Pliocene rocks on Marine Plain, Princess Elizabeth Land, documents the only post-Miocene occurrence of decapod crustaceans in the Antarctic. The badly crushed, partial remains, probably an exuvia, are encrusted with the serpulid worm, Spirorbis Daudin.
Ice front fluctuation, iceberg calving flux and mass balance of Victoria Land glaciers
Authors: Frezzotti Massimo
Published: December 2007

The coast of Victoria Land extends from Williamson Head (69°11'S, 158°E) to McMurdo Sound (77°S, 163°E). A comparison of various documents and images spanning several decades has allowed the ice front fluctuation and the iceberg calving flux during this century to be estimated. During the periods from 1956–65 to 1972–73 the floating glaciers underwent a reduction of 978 km2 with an iceberg calving flux of about 134 km2 yr−1. After this, during the periods from 1972–73 to 1989–91, the floating glaciers underwent an advance of 272 km2 with an iceberg calving flux of about 53 km2 yr−1. Glacier tongues with bottom accretion calve less often than those with bottom melting. Most floating glaciers have shown cyclic behaviour without a strong trend. Exceptions to this general style are Hells Gate ice shelf, McMurdo Ice Shelf and floating glaciers of Cape Adare which have undergone a significant retreat since the beginning of the 20th century. The different behaviour of these floating glaciers has been hypothesized as being due to: increased energy available for meltwater production of marine ice that progressively warmed these thin ice shelves and then increased iceberg calving (Hells Gate and McMurdo), or to increased melting at the ice-ocean interface related to a major intrusion of Circumpolar Deep Water from the nearby continental slope (Cape Adare). An estimate of the mass balance of East Antarctica from which these glaciers are fed shows a positive value, that is significant despite all the uncertainties of balance measurements.
An assessment of UK Meteorological Office numerical weather prediction analyses and forecasts for the Antarctic
Authors: Leonard S. , Turner J. , Milton S.
Published: December 2007

The performance of the UK Meteorological Office operational numerical weather prediction system in the Antarctic is examined. The analysis/forecast model currently has a reasonable representation of the atmospheric circulation, although there are some problems. During the first three days of the forecasts the katabatic winds in the coastal region become too strong compared to those in the initial fields, which results in coastal easterly winds that are too strong. However, the pattern of katabatic winds across the continent is broadly correct, suggesting that there are no major errors in the model orography used. The forecast tropospheric temperatures are generally too cold, although positive errors are found inland of the coast in the region of descent associated with the katabatic wind circulation. The mean forecast low pressure centres within the circumpolar trough are in approximately the correct locations, although the depth of the centres is too deep. During January there is good agreement between the model total cloud amount over the Antarctic and the estimates of total cloud cover from in situ observations. However, in July the model has too much cloud. There is no significant change in the amount of cloud during the first three days of the forecasts. The model has a good representation of the broadscale field of snow accumulation across the Antarctic. A comparison of various 6 hour forecast model fields against observations confirms the errors noted in the three-day forecasts when compared against analyses
Science vs the Environment
Authors: Howard-Williams Clive
Published: December 2007

The Environmental Protocol to the Antarctic Treaty is rapidly approaching ratification, and nations which have now signed it see the Protocol as a signal for considerable future debate, if not scrutiny. Everyone has begun to implement, at least in spirit, many of its requirements which are now beginning to have an effect on science on the continent. This is currently evident in at least four different ways:

a reallocation of funding from pure science, to ï¿½appliedï¿½ science relating to human impacts,

an increase in funding to allow for studies of human impact and the meeting of Protocol obligations,

a reassessment by the science community on what can be done with minimal impact, and

an imposition on the science community of rules and codes which will restrict many types of scientific work that have been carried out in the past, and will force modifications of future work.

Because all science on the continent (as opposed too remote sensing from space) will have an impact
there will have to be tradeoffs between the benefit to science and the impact of doing the work. We can only evaluate impacts on those areas of science that we know about at present. The problem is that there will be future, presently unknown areas of science that may be compromised by operations currently considered ï¿½safeï¿½. Who knows, for instance, what viruses we are inadvertently spreading and what the importance of these will be in future studies? At present the effects of these organisms are difficult to measure but studies on the role of viruses in natural ecosystems are increasing as technology expands.
Short-term variations in particulate matter flux in Terra Nova Bay, Ross Sea
Authors: Fabiano Mauro , Chiantore Mariachiara , Povero Paolo , Cattaneo-Vietti Riccardo , Pusceddu Antonio , Misic Cristina , Albertelli Giancarlo
Published: December 2007

As part of the Ross Sea Marginal Ice Zone Ecology Project (ROSSMIZE) the summer organic matter flux through the water column was measured at 40 m depth in Terra Nova Bay. Water samples and material from a sediment trap on the sea-bottom were analysed for their biochemical composition. A close coupling between biochemical composition of the organic matter in the water column and the material collected in the sediment trap was found, resulting from complex interactions between physical and biological processes. The physical processes are related to break-up and melting of the ice cover and occur mainly in the early summer season, whilst biological processes play a key role in mid summer and, from the evidence from faecal pellets, are related to the primary production and consumption processes.
Characterization of a hydrocarbon degrading psychrotrophic Antarctic bacterium
Authors: Cormack Walter P. Mac , Fraile Elda R.
Published: December 2007

Antarctic soil chronically exposed to gas-oil was analysed in order to isolate and study the growth conditions of hydrocarbon degrading bacteria. Soil samples taken near the shoreline in Jubany Station (King George Island, South Shetland Islands) were used as inoculum in liquid culture media with crude oil as sole carbon source. A psychrotrophic Acinetobacter strain was isolated and selected for further investigations. Effects were studied of temperature, initial pH, NaCl concentration and different chemical structure of the hydrocarbon on growth. Degradation rate was determined with n-dodecane and n-hexadecane. Growth of Acinetobacter ADH-1 showed no differences at an initial pH of 7.0, 7.5 and 8.0. Optimum temperature ranged between 25–30°C but the strain was capable of growing on n-dodecane at 4°C. Growth was observed in the presence of 3.5% NaCl. A decrease in the surface tension values was observed in the culture broth during the first 20 h of incubation (from 68 din cm−1 to 31 din cm−1). This proved to be related to the cellular fraction of the culture. The study shows that Acinetobacter ADH-1 is a psychrotrophic bacteria able to grow with hydrocarbons as sole carbon and energy source and could be potentially useful to design bioremediation processes in temperate and cold climate areas.
Detection of human commensals in the area around an Antarctic research station
Authors: Upton M. , Pennington T.H. , Haston W. , Forbes K.J.
Published: December 2007

Human contamination of Antarctic environments is a sensitive issue and has been the focus of many research articles over the past 35 years. The majority of these studies have targeted waste materials and various hydrocarbons, with assessment of microbial contaminants being largely restricted to sewage outfalls. The present study aimed to detect bacteria of human origin in the area surrounding Halley research station. It was apparent from both molecular and culture methods that bacteria of human origin are extremely difficult to detect outside the immediate surrounding of the buildings, though recommendations are made for increasing the probability of determining the presence of organisms in the environment. The results also indicate that molecular methods are more sensitive than cultural techniques, in that the only evidence for organisms in the environment surrounding the buildings came from positive PCR reactions. PCR would appear to be a useful method for studying the microbial ecology of Antarctic environments.
Observations on “cryoplanation” benches in Antarctica
Authors: Hall Kevin
Published: December 2007

A series of benches on nunataks of Alexander Island (Antarctica) are described. An increase in bench size with distance away from the retreating glacier suggests an age spectrum. The benches have thermal contraction cracks (in bedrock) on shallower, upper sections of the risers as well as salt encrusted runnels on the steeper lower section of the tread. The benches also show a distinct orientational preference (orientated to the north through to west) and, from first principles, these seem to be the aspects with optimal freeze-thaw cycles and temperatures conducive to thermal stress fatigue. The extensive dilatation associated with the retreating glaciers is thought to play a significant role in the origin and development of the benches as the combination of extensive jointing and optimal process conditions are thought to constrain where benches begin. The jointing, aided by the thermal contraction cracking, then facilitates extension and continued weathering of the treads. It would appear that these benches are examples of so called “cryoplanation terraces” that have been reported as fossil forms in Europe and North America. The study of such active forms in the Antarctic may provide good analogues for fossil features found in the Northern Hemisphere.
Early winter ice and snow thickness distribution, ice structure and development of the western Ross Sea pack ice between the ice edge and the Ross Ice Shelf
Authors: Jeffries Martin O. , Adolphs Ute
Published: December 2007

A study of early winter first-year sea ice conditions and development in the western Ross Sea in May and June 1995 included measurements of snow and ice thickness, freeboard, ice core structure and stable isotopic composition. These variables showed strong spatial variability between the Ross Ice Shelf and the ice edge 1400 km to the north, and indicate that the development of the Ross Sea pack ice is quite different from that observed in other Antarctic sea ice zones. The thinnest snow and ice occurred in a 200 km wide coastal zone. The thickest snow and ice were observed in a continental shelf zone 200–600 km from the coast where the average ice thickness (0.8 m) determined by drilling is as thick as first-year sea ice later in winter elsewhere in Antarctica. A zone of moderate snow and ice thickness occurred on the deep ocean from 600 km to the ice edge at 1400 km. Thermodynamic thickening of the ice in the inner pack ice, <800 km from the coast, was dominated by congelation ice growth, which occurred in a greater amount (65%) and in thicker layers (mean: 20 cm) than was observed in the outer pack ice >800 km from the coast (amount: 22%; mean layer thickness: 12 cm) and elsewhere in the Antarctic pack ice. The preponderance of congelation ice in the inner pack ice might be due to a low oceanic heat flux on the Ross Sea continental shelf, and a colder, less stormy environment which favours the more frequent and prolonged calm conditions necessary for significant congelation ice growth. In the outer pack ice, thermodynamic thickening occurred mainly by snow ice formation (mean layer thickness: 20 cm) while dynamic processes, i.e., rafting and ridging, caused the thickening of frazil ice and columnar ice (mean layer thickness: 14 cm and 12 cm respectively). A greater amount of snow ice (37%) occurred in the outer pack ice than in the inner pack ice (15%), and both values indicate that in the Ross Sea, unlike other Antarctic sea ice zones, there can be significant seawater flooding of the snow/ice interface and snow ice formation before midwinter.
Seabed topography under the southern and western Ronne Ice Shelf, derived from seismic surveys
Authors: Johnson M.R. , Smith A.M.
Published: December 2007

Seismic reflection measurements of ice thickness and water-column thickness have been made over the southern and western Ronne Ice Shelf, from which, the seabed elevation has been determined. A 2300 km traverse, covering an area over which little bathymetric data previously existed and at a station interval of 15 km, resulted in 152 new measurements of the seabed elevation. The seismic velocity in the ice shelf was determined using shallow refraction surveys for the snow and firn in the upper 100 m of the ice shelf, and by applying a model assuming a simple temperature profile for the deeper ice. Surface elevations were calculated assuming the ice to be in hydrostatic equilibrium. The estimated error in the seabed elevations is ±15 m. With the addition of the new data there is now complete coverage of the seabed elevation and water-column thickness for Ronne Ice Shelf at a spatial resolution of between 10–100 km. The seabed in the area to the south of Korff and Henry ice rises and the Doake Ice Rumples is about 100 m shallower than had previously been speculated, which will affect the validity of previous assumptions of water circulation and ice-ocean interaction in this area.
Katabatic wind propagation over the western Ross Sea observed using ERS-1 scatterometer data
Authors: Marshall Gareth J. , Turner John
Published: December 2007

Wind fields derived from ERS-1 scatterometer data, acquired over the open water present in the western Ross Sea during the summer season, are used to study the patterns of mesoscale atmospheric flow connected with surges of katabatic air from the Terra Nova Bay convergence zone, located in the coastal region of Victoria Land. These katabatic winds may turn northward but also southward, or divide into separate northward- and southward-turning components; the latter situation is illustrated by a detailed case study. Analysis of concurrent AWS data, suggests that the most likely mechanism for the observed southward turning is the existence of a highly-localised low pressure centre south of Terra Nova Bay. Comparison of multitemporal ERS-1 scatterometer wind fields with AWS wind measurements demonstrate that the satellite data are: (i) able to correctly portray changes in mesoscale circulation patterns, and (ii) suitable for the routine monitoring of winds over open water around the Antarctic coastline, despite a less than ideal temporal coverage.
An earth modified by global change – but how much do we know about the evolution of our planet?
Authors: Wilson C.
Published: December 2007

This issue contains contributions from a Prince Charles Mountains workshop and the Selwyn Symposium, held at The University of Melbourne in October 1996. The A.R. Selwyn Lecture, presented by Pat Quilty, raised key questions about the new relationships between scientists and administrators and the way that science is justified and funded. Non-scientists are taking a far greater role in deciding the directions of science and the questions that will be addressed. He highlighted the follies in the current fashion of using the last million years of geological history to understand global change and how this misses the point that much more dramatic changes have occurred in earth history including those recorded in some of Antarctica's older rocks.
A preliminary survey of cryobiontic algal communities from Cierva Point (Antarctic Peninsula)
Authors: Mataloni Gabriela , Tesolín Gustavo
Published: December 2007

Algal communities colouring snow and ice were studied at fourteen sites on Cierva Point (Danco Coast, Antarctic Peninsula). Chlorophyta were the dominant group in cryobiontic communities, both in species richness and abundance. Cyanobacteria and diatoms, in turn, showed a higher species number at low altitude, well drained temporary snow fields, probably denoting a cryoxenic character. Descriptions of the six species newly recorded for Antarctica are given, and the taxonomic position of some Scotiella, Trochiscia and Koliella species is discussed. Further research is needed to assess the importance of various stress factors in the progressive drop in species richness and biosynthesis of secondary carotenoids associated with a change in snow colour from green to orange-red to pink-red.
Gondwanan floristic and sedimentological trends during the Permian–Triassic transition: new evidence from the Amery Group, northern Prince Charles Mountains, East Antarctica
Authors: McLoughlin Stephen , Lindström Sofie , Drinnan Andrew N.
Published: December 2007

The Permian–Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular occurrence of Lunatisporites pellucidus and the first appearance of Aratrisporites and Lepidopteris species. The Permian-Triassic boundary is marked by the extinction of glossopterid and cordaitalean gymnosperms, and by the disappearance or extreme decline of a range of gymnospermous and pteridophytic palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical red-bed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian–Triassic boundary suggests that factors independent of, or additional to, climate change were responsible for the turnover in terresrtial floras.
Blanketing snow and ice; constraints on radiocarbon dating deglaciation in East Antarctic oases
Authors: Gore Damian B.
Published: December 2007

Radiocarbon dating of marine, lacustrine or terrestrial biogenic deposits is the main technique used to determine when deglaciation of the oases of East Antarctica occurred. However, at many of the oases of East Antarctica, including the Schirmacher Oasis, Stillwell Hills, Amery Oasis, Larsemann Hills, Taylor Islands and Grearson Oasis, snow and ice presently forms extensive blankets that fills valleys and some lake basins, covers perennial lake ice and in places overwhelms local topography to form ice domes up to hundreds of square kilometres in area. Field observations from Larsemann Hills and Taylor Islands suggest that under these conditions, terrestrial and lacustrine biogenic sedimentation is neither widespread nor abundant. If similar conditions prevailed in and around the oases immediately following retreat of the ice sheet, then a lengthy hiatus might exist between deglaciation and the onset of widespread or abundant biogenic sedimentation. As a result, radiocarbon dating might be a clumsy tool with which to reconstruct deglaciation history, and independent dating methods that record emergence of the hilltops from the continental ice must be employed as well.
Reconstruction of ice flow across the Bunger Hills, East Antarctica
Authors: Augustinus Paul C. , Gore Damian B. , Leishman Michelle R. , Zwartz Dan , Colhoun Eric A.
Published: December 2007

In the Bunger Hills, mapping of glacial drift sheets and examination of striae patterns and other palaeo-ice flow direction indicators show that the largely ice-free region records the imprint of ice sheet expansion(s) during the late Cenozoic. In particular, ice moulded features and striae in southern Bunger Hills suggest formation during at least two episodes of ice sheet expansion, although whether they were formed during separate events or merely different phases of the same expansion of the ice sheet is not able to be discerned at present. The older event relates to thin ice with flow constrained by the topography, whilst the younger event relates to regional expansion of thick ice across the area. Discrimination of the order of emplacement of the cross-cutting striae patterns is possible at a number of sites. Palaeo-ice flow indicators confirm that ice sheet expansion over southern Bunger Hills was purely from the southern and eastern margins, although minor advances of the north-east flowing Edisto Glacier onto coastal areas occurred following retreat of the last extensive ice sheet phase.
An analysis of a 34-year air temperature record from Fossil Bluff (71°S, 68°W), Antarctica
Authors: Harangozo Stephen A. , Colwell Steven R. , King John C.
Published: December 2007

An analysis of a long-term surface air temperature record for Fossil Bluff in the George VI Sound, West Antarctic Peninsula (WAP) documents in detail some important aspects of the climate of this area for the first time. The analysis identifies the close dependency of air temperatures on latitude in the WAP but reveals that the strength of this dependency is greatest in winter. This result along with others leads to the Fossil Bluff climate regime being characterized as ‘continental’ rather than ‘maritime’ as found further north. The WAP as a whole displays large interannual temperature variability but this is greatest in Marguerite Bay rather than the Fossil Bluff area. Evidence is also provided for secular climatic change appearing in summer throughout the WAP over the last few decades. The representativeness of existing Antarctic Peninsula annual air temperature climatologies, based mainly on snow temperature measurements, for the winter and summer periods is also noted.
Molecular evidence for cryptic species among the Antarctic fish Trematomus bernacchii and Trematomus hansoni
Authors: Bernardi Giacomo , Goswami Usha
Published: December 2007

The notothenid species Trematomus bernacchii has previously been shown, by allozyme analysis, to be a complex of two cryptic species, one of which being more closely related to T. hansoni than to the other T. bernacchii cryptic species. Two T. bernacchii colour morphs, “white blotch” and “brown”, at McMurdo Sound, may correspond to these cryptic species. In this study, we present mitochondrial DNA sequences of the 12S and 16S ribosomal regions for six “white blotch” morphs, eight “brown” morphs collected in McMurdo Sound, one individual collected off the Antarctic Peninsula, and two T. hansoni individuals from McMurdo Sound. These sequences were compared with those of T. bernacchii and T. hansoni in the literature. Based on 14 phylogenetically informative sequences, no differences were found between “white blotch” and “brown” morphs. Furthermore, only one substitution separated these sequences from the previously published T. hansoni sequence, while 10 substitutions separated them from the previously published T. bernacchii sequence. Misidentified specimens, and sequence misreadings may be at the origin of these discrepancies. However, the presence of cryptic species within T. bernacchii and T. hansoni is not ruled out.
The summer diet of demersal fish at the South Shetland Islands
Authors: Takahashi Masanori , Iwami Tetsuo
Published: December 2007

The stomach contents of demersal fish in late January 1982 were analysed. Samples were taken at 100, 300 and 500 m depth south of Elephant Island, Bransfield Strait and north of Livingston Island, and at 800 m to the east of Smith Island. Fifty four taxa of fish belonging to 11 families were collected. The diets of 2101 fish representing 38 taxa were examined. These were classified into three categories, fish feeders, krill feeders and benthos feeders. Fish prey species fed on krill and/or benthos. Krill was a major dietary component for 32 (84.2%) out of 38 taxa. Gobionotothen gibberifrons was distributed at all 10 stations (100–800 m in depth) and its diet comprised krill and benthos. The present findings verify the importance of krill in the Antarctic marine ecosystem and indicate that krill is consumed by benthic fish at greater depths than previously reported.
Late Jurassic (Kimmeridgian-Tithonian) macrofossil assemblage from Jason Peninsula, Graham Land: evidence for a significant northward extension of the Latady Formation
Authors: Riley T.R. , Crame J.A. , Thomson M.R.A. , Cantrill D.J.
Published: December 2007

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.
Sensitivity of the Antarctic sea ice distribution to its advection in a general circulation model
Authors: Wu Xingren , Budd W.F. , Simmonds Ian
Published: December 2007

A dynamic-thermodynamic sea ice model is used and coupled with an atmospheric general circulation model to simulate the seasonal cycle of the global sea ice distribution. We have run the coupled system and obtain a creditable seasonal simulation of the Antarctic sea ice. To understand the role of ice advection on the seasonal cycle of Antarctic sea ice in the coupled system, results from the thermodynamiconly (T) sea ice model have been compared with those from the dynamic thermodynamic (DT) sea ice model. The seasonal cycle of sea ice differs between the two models. When ice motion is eliminated sea ice becomes more compact and thinner, and sea ice is more extensive in summer. A number of previous studies have examined the effect of ice dynamics on sea ice simulations with prescribed atmospheric conditions. Here experiments have been performed with a fully coupled atmosphere sea ice system and also using prescribed daily atmospheric forcing and monthly mean atmospheric forcing, to examine the differences of the sensitivity of the ice advection between the coupled and forcing models. Similar differences have been observed between DT and T in the forcing models but the magnitude is smaller than in the fully coupled model, and with monthly mean atmospheric forcing the difference is least. These differences highlight the importance of the inclusion of ice advection when undertaking studies using a fully interactive atmosphere sea ice model, or using prescribed daily/monthly atmospheric conditions to force a sea ice model for the Antarctic.
Tephra analysis of sediments from Midge Lake (South Shetland Islands) and Sombre Lake (South Orkney Islands), Antarctica
Authors: Hodgson Dominic A. , Dyson Coral L. , Jones Vivienne J. , Smellie John L.
Published: December 2007

Lake sediment cores from Midge Lake, Livingston Island, South Shetland Islands and Sombre Lake, Signy Island, South Orkney Islands were analysed for volcanic tephra using light microscopy and magnetic susceptibility. Cores were dated using published 14C and 210Pb chronologies. Electron probe microanalyses of discrete tephra glass shards were undertaken to characterise the tephra geochemically in order to identify possible source volcanoes and refine tephrochronological data for the region. Results identified five tephra horizons in a core from Midge Lake. Four of these tephra at 3–4 cm, 8–9 cm (c. 450 yr BP), 15–16 cm (c. 755 ± 105 yr BP) and 21–22 cm (c. 1340 ± 100 yr BP) consisted of sodic basaltic to basalticandesitic glasses, containing abundant labradoritic feldspar inclusions, and a single ‘acidic’ tephra was found at 2–3 cm. Seven tephra horizons were identified in the Sombre Lake core including three basaltic tephra at 3–9 cm (30 ± 4 yr BP to 125 ± 25 yr BP), 31–32 cm and 44–46 cm (1325 ± 50 14C yr BP) and four acidic tephra at 21–22 cm and 24–25 cm, 33–36 cm (c. 1021 14C yr BP) and 54–56 cm (c. 1450 14C yr BP). These are the first tephra to be identified from the South Orkney Islands. Geochemical and grain size analysis indicated that the analysed Midge Lake tephra were derived from the Quaternary Deception Island volcano. Smaller grain sizes, congruent geochemical data and prevailing wind directions also indicate this volcano as the likely source of Sombre Lake tephra. Results highlight the importance of establishing geochemical consistency between tephra deposited across wide geographical areas, during apparently synchronous time periods, if they are to be used in a regional tephrochronology.
Photosynthetic parameters and empirical modelling of primary production: a case study on the Antarctic Peninsula shelf
Authors: Moline Mark A. , Schofield Oscar , Boucher Nicolas P.
Published: December 2007

Eight hundred photosynthesis-irradiance relationships were determined in the shelf waters adjacent to Palmer Station, Antarctica during the spring/summer periods of 1991–94. Biomass specific maximum photosynthetic rate, PBmax, and the light limited photosynthetic efficiency, αB, were poorly correlated to the physical forcing and nutrient regimes at the sampling stations. The two photosynthetic parameters, however, did strongly covary indicating the minimum irradiance required to saturate photosynthesis, Ik, was relatively constant in this highly variable environment. The variability in Ik could partially be attributed to both depth in the water column and time of the year, with the highest values occurring for surface samples during the summer period of peak incident irradiance. Given this and the significant dependence of Pmax on phytoplankton biomass, a simple empirical model for primary productivity was developed. An independent test of the model was performed on data collected in a mesoscale offshore grid and predicted primary production was found to be within 13% of measured values. Although there are limitations to this approach (i.e. exclusion of diel periodicity in photosynthetic response), these results provide relatively robust estimates of daily primary production for the Southern Ocean.
Diet of two Antarctic dragonfish (Pisces: Bathydraconidae) from the Indian sector of the Southern Ocean
Authors: Pakhomov Evgeny A.
Published: December 2007

The diet of Cygnodraco mawsoni Waite 1916 and Gymnodraco acuticeps Boulenger 1902 (Pisces: Bathydraconidae) was studied in the Cooperation and Cosmonaut seas in the depth range 200–400 m during the summer 1988. Stomach content analysis showed that both species are piscivorous predators but with different feeding habits. Cygnodraco mawsoni fed mostly on young notothenioid fish, regularly complementing these with pelagic, Euphausia superba, and benthic crustaceans, such as amphipod gammarids and mysids. In contrast, G. acuticeps relied mostly on mesopelagic fish of the family Myctophidae. Although C. mawsoni and G. acuticeps occupy similar depths in the Cosmonaut Sea, different feeding habits appear to limit the probability of interspecific competition for food.