bluuebunny/crossref_metadata_2025 huggingface dataset:
Record of Holocene glacial oscillations in Bransfield Basin as revealed by siliceous microfossil assemblages
Authors: Bárcena M. Angeles , Gersonde Rainer , Ledesma Santiago , Fabrés Joan , Calafat Antonio M. , Canals Miquel , Sierro F. Javier , Flores Jose A.
Published: December 2007

Two gravity cores, Gebra-1 and Gebra-2 from the central and eastern basins of Bransfield Strait, West Antarctica, consist mainly of hemipelagic, laminated muds with black layers rich in sand-sized volcanic ash. Micropalaeontological (diatoms and radiolarians) and geochemical (organic and inorganic) analyses, together with radiometric dating (U/Th, 14C and 210Pb) have been performed on both cores. AMS analyses on Total Organic Carbon yielded a 14C-age older than expected, 2810 yr BP for the core top of Gebra-1 and 2596 yr BP for Gebra-2. The downcore pattern of ages indicates a sedimentation rate of 130 cm kyr1 for Gebra-1 and 160 cm kyr1 for Gebra-2 210Pb anomalies suggest the core top of Gebra-1 is present-day sediment. The diatom and radiolarian assemblages are related to the sequence of neoglacial events over the last three millennia. The recent significant reduction in Chaetoceros resting spores is interpreted as a reduction in palaeoproductivity. The progressive increase in sea-ice taxa for the last three millennia may indicate a cooling trend. Greater sea-ice coverage during the coldest neoglacial events in the Bransfield Basin, as well as in the Weddell Sea and Bellingshausen Sea, is documented by increases in sea-ice taxa and reductions in Thalassiosira antarctica/ T. scotia resting spores, Fragilariopsis kerguelensis, the Lithomelissa group and the “circumpolar” group of radiolarians. For these periods, we postulate a restricted communication between the Weddell Sea, Bellingshausen Sea and Bransfield basin. The millenial-scale changes are overprinted by a high frequency cyclicity at about 200–300 yrs, which might be related to the 200–yrs solar cycle.
Circum-Antarctic coastal environmental shifts during the Late Quaternary reflected by emerged marine deposits
Authors: Berkman Paul A. , Andrews John T. , Björck Svante , Colhoun Eric A. , Emslie Steven D. , Goodwin Ian D. , Hall Brenda L. , Hart Charles P. , Hirakawa Kazuomi , Igarashi Atsuo , Ingólfsson Olafur , López-Martínez Jeronimo , Lyons W. Berry , Mabin Mark C.G. , Quilty Patrick G. , Taviani Marco , Yoshida Yoshio
Published: December 2007

This review assesses the circumpolar occurrence of emerged marine macrofossils and sediments from Antarctic coastal areas in relation to Late Quaternary climate changes. Radiocarbon ages of the macrofossils, which are interpreted in view of the complexities of the Antarctic marine radiocarbon reservoir and resolution of this dating technique, show a bimodal distribution. The data indicate that marine species inhabited coastal environments from at least 35 000 to 20 000 yr BP, during Marine Isotope Stage 3 when extensive iceberg calving created a ‘meltwater lid’ over the Southern Ocean. The general absence of these marine species from 20 000 to 8500 yr BP coincides with the subsequent advance of the Antarctic ice sheets during the Last Glacial Maximum. Synchronous re-appearance of the Antarctic marine fossils in emerged beaches around the continent, all of which have Holocene marine-limit elevations an order of magnitude lower than those in the Arctic, reflect minimal isostatic rebound as relative sea-level rise decelerated. Antarctic coastal marine habitat changes around the continent also coincided with increasing sea-ice extent and outlet glacial advances during the mid-Holocene. In view of the diverse environmental changes that occurred around the Earth during this period, it is suggested that Antarctic coastal areas were responding to a mid-Holocene climatic shift associated with the hydrological cycle. This synthesis of Late Quaternary emerged marine deposits demonstrates the application of evaluating circum-Antarctic phenomena from the glacial-terrestrial-marine transition zone.
Changing SCAR
Authors: Walton David W.H.
Published: December 2007

Change is in the air - not just a mild breeze, more of an impending storm. At XXV SCAR in Concepcion, much of the talk at Working Groups and at the Delegates meeting was of change. But why, how and when?
Epibiotic relationships in the Antarctic benthos
Authors: Gutt Julian , Schickan Thomas
Published: December 2007

On the high Antarctic shelf, 374 different epibiotic relationships of the megafauna were photographically registered and statistically analysed. These comprised 47 different epibiotic and 96 substratum taxa and had obvious differences in abundance and presence in three different benthic assemblages. Six abundant obligatory relationships in which the epibiont occurred almost exclusively on one type of substratum had highly specialized epibionts. For an additional eight relationships, a statistical test revealed that the epibionts preferred specific living and elevated mineral substrata. Most of these relationships are interpreted as commensalism (sensu Odum) in which the suspension feeding epibiont profits from the elevated position. Here it has better access to food compared with life on the sediment. The evolution of a rich and mainly sessile epifauna on parts of the high Antarctic shelves and the successful development of epibiotic behaviour in other species are suggested as a major reason for the high species richness in the benthic fauna. The results provide evidence that the Antarctic megabenthos is more biologically accommodated than physically controlled.
Krill transport in the Scotia Sea and environs
Authors: Hofmann Eileen E. , Klinck John M. , Locarnini Ricardo A. , Fach Bettina , Murphy Eugene
Published: December 2007

Historical observations of the large-scale flow and frontal structure of the Antarctic Circumpolar Current in the Scotia Sea region were combined with the wind-induced surface Ekman transport to produce a composite flow field. This was used with a Lagrangian model to investigate transport of Antarctic krill. Particle displacements from known krill spawning areas that result from surface Ekman drift, a composite large-scale flow, and the combination of the two were calculated. Surface Ekman drift alone only transports particles a few kilometres over the 150-day krill larval development time. The large-scale composite flow moves particles several hundreds of kilometres over the same time, suggesting this is the primary transport mechanism. An important contribution of the surface Ekman drift on particles released along the continental shelf break west of the Antarctic Peninsula is moving them north-northeast into the high-speed core of the southern Antarctic Circumpolar Current Front, which then transports the particles to South Georgia in about 140–160 days. Similar particle displacement calculations using surface flow fields obtained from the Fine Resolution Antarctic Model do not show overall transport from the Antarctic Peninsula to South Georgia due to the inaccurate position of the southern Antarctic Circumpolar Current Front in the simulated circulation fields. The particle transit times obtained with the composite large-scale flow field are consistent with regional abundances of larval krill developmental stages collected in the Scotia Sea. These results strongly suggest that krill populations west of the Antarctic Peninsula provide the source for the krill populations found around South Georgia.
Genetic variation and dispersal of Bryum argenteum and Hennediella heimii populations in the Garwood Valley, southern Victoria Land, Antarctica.
Authors: Selkirk P. M. , Skotnicki M. L. , Ninham J. , Connett M. B. , Armstrong J.
Published: December 2007

A detailed study was made of the extent of genetic variation within populations of two moss species, Bryum argenteum and Hennediella heimii, from the Garwood Valley in Southern Victoria Land, Antarctica. RAPD (Random Amplified Polymorphic DNA) technology was used to analyse over 30 clumps of each species, collected from adjacent sites in five small meltstream drainage channels. Overall, extensive genetic variation was found, with no two samples being identical in either species. For both species, most clumps showed within-clump variation, although generally the shoots from each clump were most closely related to other shoots from that clump, indicating somatic mutation. Of the B. argenteum isolates, most showed distinct clustering corresponding to the five drainage channels, with some clustering within the top, middle or bottom of the channels, and separation of northern and southern sides of the valley. There was some evidence of across-channel dispersal for B. argenteum. For H. heimii, the situation was quite different; there was very little clustering of clumps according to channel from which they were collected. Rather, the isolates appeared to form one continuous population across the five channels, with partial separation of northern and southern sides of the valley. These results are consistent with the predicted means of dispersal of these species in Antarctica: predominantly by water for B. argenteum, and by wind for H. heimii.
The origin of salts in water bodies of the McMurdo Dry Valleys
Authors: Takamatsu Nobuki , Kato Naoyuki , Matsumoto Genki I. , Torii Tetsuya
Published: December 2007

Lithium distributions in lake and pond waters of the McMurdo Dry Valleys of southern Victoria Land, Antarctica were studied to elucidate the origin of dissolved salts and the evolutionary history of the lakes and ponds. The EfLi [(Li/Cl)sample/(Li/Cl)seawater] values of the bottom waters in Lakes Bonney and Fryxell were higher than unity (EfLi=4–7), indicating that the salts originated from sea salts (probably relict seawater) and have been subsequently modified by the contribution of meltwaters containing atmospheric fallout and/or rock and soil weathering products. In contrast, extremely high Li concentrations with high EfLi values in the Don Juan Pond water (EfLi = 180) and the bottom waters of Lake Vanda (EfLi = 40) suggest that the salts originated from deep groundwaters influenced mainly by saline water-rock interactions, as supported by the dissolution experiments of granite in NaCl solution. The low Li concentrations of pond waters with high EfLi values in the Labyrinth indicate that the salts are derived from atmospheric fallout. The decrease of the EfLi values with the increase of Cl concentrations can be explained by the repeated cycles of the migration of Li into the ice phase and subsequent ablation of surface ice, as indicated by seawater freezing experiments.
Minettes from Schirmacher Oasis, East Antarctica — indicators of an enriched mantle source
Authors: Hoch Marion , Tobschall Heinz J.
Published: December 2007

Minette dykes intersect the Precambrian crystalline basement of Schirmacher Oasis, East Antarctica. The rocks have intermediate to basic compositions, showing shoshonitic to ultrapotassic character. The samples show enhanced concentrations of compatible elements and high mg# combined with extreme enrichments in LILE (especially Ba) and LREE. Mantle-normalized trace element patterns are characterized by coupled relative depletions of Nb and Ti and strong fractionations between LILE and HFSE. The minettes display fractionated chondrite-normalized REE patterns with high and varying LREE concentrations in contrast to relative low and nearly constant HREE contents. High magma-ascent and cooling rates of lamprophyric magmas argue against a fundamental change of the primary geochemical signatures in minette magmas by interactions with the continental crust during ascent. The major and trace element abundances of the studied minettes point to varying degrees of partial melting of a mantle source, which was enriched in LILE and LREE during or before the melting event. Incompatible element signatures argue for the involvement of subducted pelagic sediments.
Solution geochemistry and behaviour of major and trace elements during summer in a moss community at Edmonson Point, Victoria Land, Antarctica
Authors: Bargagli R. , Smith R.I.L. , Martella L. , Monaci F. , Sanchez-Hernandez J.C. , Ugolini F.C.
Published: December 2007

Physical and chemical characteristics and solution geochemistry of major and trace elements were investigated in an area of volcanic soil colonized by mosses at Edmonson Point (central Victoria Land) during the international BIOTAS (Biological Investigations of Terrestrial Antarctic Systems) expedition (BIOTEX) in the 1995–96 summer. The broad objective was to study the environmental factors involved in plant colonisation and survival in terrestrial continental Antarctic ecosystems. The results showed that moss distribution and survival throughout the summer was closely dependent on water supply. In Antarctic coastal ecosystems the environmental biogeochemistry is largely dominated by ions of marine origin. At the drier end of a hydrological gradient the dry cushions of Hennediella heimii were encrusted with salts and showed much higher concentrations of soluble ions (Na+, Cl−, K+, Ca2+, Mg2+, SO42−, NO3−) than those in adhering soil particles or in other moss species from wetter parts of the transect. Although salt encrustations may partly derive from sublimation of surface snow, comparisons between concentrations of soluble ions in the dry moss and those in the < 2 mm fraction of surface and deep soil showed an upward migration along the soil profile of soluble ions as the substratum dried out, between December and January, and their accumulation mostly on mosses. At the wet end of the transect messes were less affected by salt encrustations and there was evidence of Ca2+ uptake and an active cycling of nutrients.
Microhabitats occupied by terrestrial arthropods in the Stillwell Hills, Kemp Land, East Antarctica
Authors: Kennedy Andrew D.
Published: December 2007

A fine-scale survey of the distribution of free-living terrestrial arthropods in the Stillwell Hills region of Kemp Land, East Antarctica, was carried out between 22 December 1996 and 27 January 1997. Three species, all Acari, were recorded: Protereunetes maudae Strandtmann, Nanorchestes triclivatus Booth and N. lalae Strandtmann. Population densities varied from 0 to 6802 ind. m−2 with a mean of 954 ind.m−2. The favoured microhabitat was found to be beneath stones in damp locations on north- and west-facing slopes. Sites with microalgal growth supported more microarthropods than sites with mosses, lichens and macroalgae. Arid and saline habitats, including such sites as wind-sweptridges and the seashore, were found to lack microarthropods. Thermal and humidity profiles above and below the ground surface were recorded to investigate the microenvironments of Acari. Special attention was focused upon the moderating role of snow thickness, vegetation cover, aspect and vertical depth in the soil profile. These microclimate data suggest that Acari are able to avoid the extremes of low temperature experienced at macroclimate level but that heat stress and desiccation may play important limiting roles.
Cetacean observations during a winter voyage into Antarctic sea ice south of Australia
Authors: Thiele Deborah , Gill Peter C.
Published: December 2007

Cetacean observations were made from a platform of opportunity (a winter sea ice and oceanography research voyage) in Antarctic sea ice south of Tasmania. Minke whales and killer whales were sighted well within the sea ice. Minkes were found between 180–350 km south of the ice edge, while killer whales were nearly 450 km south of the ice edge. Minkes were sparsely distributed throughout the seasonal sea ice, even in areas of apparent total ice cover. Killer whales (including calves) were found at the northern edge of a major coastal polynya system. The winter sea ice is a complex and dynamic environment in which lead and polynya systems may enable travel and foraging by some cetacean species. While biological productivity is known to be reduced from summer levels, large numbers of seals, penguins – and possibly small numbers of whales – may be supported by krill and other biota intimately associated with the sea ice habitat during winter.
Summer distribution and abundance of larval and juvenile fishes in the western Ross Sea
Authors: Vacchi M. , Mesa M. La , Greco S.
Published: December 2007

Ichthyoplankton samples were collected during the November–December 1994 Italian Antarctic Oceanographic Cruise carried out to the western Ross Sea. A midwater trawl (Hamburg Plankton Net) was used to collect samples at 26 stations. Larval and juvenile specimens of 21 species belonging to six families (Artedidraconidae, Bathydraconidae, Channichthyidae, Macrouridae, Nototheniidae and Paralepididae) were caught from surface to 380 m depth. Mean relative abundance of larval fish in the whole area was about 2.7 specimens 1000 m−3 of filtered water. Pleuragramma antarcticum were the most abundant as postlarvae and juveniles. Larval and postlarval specimens of Chionodraco myersi were also abundant and widespread. The high number of Trematomus lepidorhinus (570 larvae) found in a single station off Terra Nova Bay (74°48′75“S, 164°36′90”E) was noteworthy. Our data demonstrate that the species diversity of the larval fish community in the western Ross Sea is much as found elsewhere in the Antarctic and show a greater abundance of fish larvae in inshore than in offshore waters.
Late Cambrian stratigraphy of the Heritage Range, Ellsworth Mountains: implications for basin evolution
Authors: Curtis Michael L. , Lomas Simon A.
Published: December 2007

Deposition of the Upper Cambrian succession of the Ellsworth Mountains was influenced by major, episodic tectonically-driven changes to the depositional basin geometry. We subdivide the succession into four stratigraphical sequences based on the recognition of three sequence-bounding unconformities. The upper part of Sequence 1 is composed of the laterally equivalent Liberty Hills, Springer Peak and Frazier Ridge formations, a siliciclastic fluvial to marine deltaic association displaying NW-directed palaeocurrents. A switch in the position of the Late Cambrian depocentre from the north-west to the south coincided with cessation of terrigenous clastic deposition and accumulation of Sequence 2, the limestones of the Minaret Formation. Previously unreported talus breccias from the Independence Hills provide important clues to basin configuration at this time. A brief period of emergence of the Minaret Formation is inferred, prior to rapid subsidence and disconformable deposition of Sequence 3 (the ‘transition beds’) in outer-inner shelf environments. Localized intra-basinal uplift occurred prior to the deposition of Sequence 4 (the lower Crashsite Group), the base of which is locally an erosive unconformity, with a correlative conformity exposed elsewhere. We interpret the Upper Cambrian succession as representing the ‘rift-drift’ transition from initial rifting (preceded by Middle Cambrian volcanism) to thermal subsidence along the South African sector of the palaeo-Pacific margin of Gondwana.
Ice shelf grounding zone features of western Prydz Bay, Antarctica: sedimentary processes from seismic and sidescan images
Authors: O'Brien P.E. , Santis L. De , Harris P.T. , Domack E. , Quilty P.G.
Published: December 2007

Several grounding zone wedges were left on the floor and flanks of Prydz Channel in western Prydz Bay by the Lambert Glacier during the last glacial cycle. Seismic profiles indicate that vertical accretion at the glacier bed was the most important depositional process in forming the wedges, rather than progradation by sediment gravity flows. Sidescan sonographs reveal extensive development of flutes on the sea floor inshore from the wedges, indicating deformable bed conditions beneath the ice. The region inshore of the east Prydz Channel wedge features extensive dune fields formed by currents flowing towards the grounding zone. This orientation is consistent with models of circulation beneath ice shelves in which melting at the grounding line generates plumes of fresher water that rise along the base of the ice shelf, entraining sea water into a circulation cell. The Lambert Deep is surrounded by a large composite ridge of glacial sediments. Internal reflectors suggest formation mostly by subglacial accretion. The sea floor in the Lambert Deep lacks dune fields and shows evidence of interspersed subglacial cavities and grounded ice beneath the glacier. The absence of bedforms reflects sea floor topography that would have inhibited the formation of energetic melt water-driven circulation.
Estimation of turbulent heat fluxes and exchange coefficients for heat at Dumont d'Urville, East Antarctica
Authors: Argentini S. , Mastrantonio G. , Viola A.
Published: December 2007

Simultaneous acoustic Doppler sodar and tethersonde measurements were used to study some of the characteristics of the unstable boundary layer at Dumont d'Urville, Adélie Land, East Antarctica during the summer 1993–94. A description of the convective boundary layer and its behaviour in connection with the wind regime is given along with the frequency distribution of free convection episodes. The surface heat flux has been evaluated using the vertical velocity variance derived from sodar measurements. The turbulent exchange coefficients, estimated by coupling sodar and tethered balloon measurements, are in strong agreement with those present in literature for the Antarctic regions.
A humidity climatology for Halley, Antarctica, based on frost-point hygrometer measurements
Authors: King J.C. , Anderson P.S.
Published: December 2007

Measurements of humidity at a height of 4 m were made at Halley Research Station between 1995 and 1997 using a frost point hygrometer. Relative humidities were usually close to ice saturation, particularly during the winter, but ice supersaturations of up to 20% were frequently measured. Supersaturation with respect to liquid water was rarely observed. During the summer, diurnal variation in temperature drove a daily cycle in relative humidity, although corresponding variations in mixing ratio were comparatively small. It is suggested that the high frequency of ice supersaturations and almost total absence of water supersaturation results from the high abundance of condensation nuclei relative to ice nuclei.
Age, sex and status of wandering albatrosses Diomedea exulans L. in Falkland Islands waters
Authors: Croxall J.P. , Black A.D. , Wood A.G.
Published: December 2007

Records (by a scientific observer on a longline fishing vessel around the Falkland Islands) of 86 different individually colour-banded wandering albatrosses from South Georgia, provide new insights into the use of the waters of the Patagonian shelf slope by birds from breeding grounds some 600 km to the south-east across the Antarctic Polar Front. Birds recorded were aged from 3–39 years, almost the full range (except 1 and 2 year olds) of South Georgia colour-banded birds, about 5% of whose colour-banded population was observed during the study. Immature birds (up to age 7 years) formed only 9% of the total; this may reflect relative absence from the area but might also relate to their subordinate status to adults at fishing vessels. Most birds seen were current breeders at South Georgia, including both sexes in the month prior to arrival on the breeding grounds (October), females during the pre-laying exodus (December) and both sexes during incubation (January) and throughout the main chick-rearing period (May, June, October). Only birds which had already failed were seen in the brooding period (March–April), when foraging trips are too short to reach the Falklands. Females outnumbered males in all these categories, supporting suggestions of different distributions of the sexes at sea during breeding. Birds of both sexes that had bred at South Georgia in the previous year were seen mainly between January and April. Birds that had not bred for at least three years were mainly males and mainly seen in January. These data indicate the importance of the waters near the Patagonian Shelf, especially around the Falklands, for wandering albatrosses from South Georgia, particularly breeding birds but also birds in their year(s) between breeding attempts. This is of particular relevance, given the globally threatened status of the species and the possibility of hydrocarbon exploitation in waters around the Falklands.
The elemental and biochemical composition of bryophytes from the maritime Antarctic
Authors: Davey Martin C.
Published: December 2007

The elemental and biochemical composition of eight moss species from the maritime Antarctic were determined fornightly (summer) or monthly (winter) from December 1992 to November 1994. Short-duration summer carbohydrate maxima in Calliergon sarmentosum were seen in both years, but no other seasonal patterns were observed. The absence of seasonality in carbon, nitrogen and phosphorus concentrations or their atomic ratios suggest that the mosses were nutrient-sufficient throughout the year, and that nutrient availability was not important in determining moss productivity. Mosses from hydric habitats had lower carbohydrate and higher protein, nitrogen and phosphorus contents than those from drier habitats, possibly as a consequence of higher productivity and continual flushing with nutrients in wet habitats. The results are consistent with the importance of water and the primacy of physical factors in the ecology of Antarctic mosses.
The Kukri Erosion Surface; a reassessment of its relationship to rocks of the Beacon Supergroup in the central Transantarctic Mountains, Antarctica
Authors: Isbell John L.
Published: December 2007

Much of Antarctica's Devonian to Jurassic geological history is interpreted from the study of the Beacon Supergroup in the central Transantarctic Mountains. The upper part of the succession has been extensively investigated, although, few studies focus on the basal rocks. Deposition occurred within a Transantarctic basin believed to have extended along the edge of the East Antarctic Craton in early Beacon time, either as a marginal, passive margin, or a cratonic basin. Early basinal deposits include the Devonian Taylor Group and Upper Carboniferous–Lower Permian glacial sediments. Previous studies concluded that the Taylor Group in CTM was deposited as a continuous sheet across the low-relief Kukri Erosion Surface that developed on the planed Ross orogenic belt. These interpretations also concluded that late Palaeozoic glaciation truncated the Devonian sheet. New data suggest that this view, and current models for the early Beacon basin, maybe incorrect. Lithofacies, palaeocurrent orientations, sandstone composition, and stratigraphical relationships of central Transantarctic Mountains rocks suggest that deposition occurred within two intermontane or successor basins following post-orogenic uplift of the Ross terrain. Segregation of lithofacies and onlap of Taylor Group rocks onto an undulating Kukri Erosion Surface show that a basement high separated non-marine deposits between the Byrd and Ramsey glaciers from marine sediment in the Ohio Range. Onlap of glacial rocks and palaeocurrent data suggest intermontane conditions continued until the Early Permian.
Glacial boulders ‘floating’ on the ice cover of Lake Untersee, East Antarctica
Authors: Wand Ulrich , Perlt James
Published: December 2007

Large glacial boulders, up to several metres in diameter, resting on the lake ice are a remarkable feature of Lake Untersee (71°21'S, 13°28'E), an ice-dammed, perennially frozen freshwater lake in the Ottovon-Gruber-Gebirge (Gruber Mountains) of central Queen Maud Land, East Antarctica. A geodetic survey of such ice-rafted boulders was made over two summer seasons to determine the direction and velocity of their movement. They are transported between 3.9 and 11.1 m annually and the residence time of the boulders is estimated at approximately 500 years. Lake Untersee must have been permanently covered with lake ice for at least that long.
Do life patterns differ between two Scotia Arc localities? A preliminary investigation of three erect Antarctic bryozoan species
Authors: Barnes David K.A.
Published: December 2007

Erect bryozoans are extremely abundant and diverse in polar waters and individual species may span a wide range in latitude and bathymetry. A number of aspects of lifestyle, including polypide recycling, embryo production, distribution, growth form and epibiosis were compared in three species of erect byozoans. These were collected from two locations; Signy Island (60°S) and Rothera Point, Adelaide Island (68°S) and a variety of depths. All three species were in similar stages of polypide cycling within and between the two sites. In the species Isosecuriflustra rubefacta and Nematoflustra flagellata the rate of brown body production (polypide generations) was slower at Signy Island than at Rothera Point. There was little difference between localities (within species) in the pattern of embryo production and no change in embryo size with depth. Embryos of I. rubefacta, however, were significantly larger at Rothera Point than at Signy Island. The proportion of the community occupied by each species changed with depth, but all three species occurred in shallower water at Rothera Point than at Signy Island. Fouling by epibionts decreased with increasing depth and from Signy Island to Rothera Point, both in terms of per cent cover and number of colonizing taxa. Possible trends with depth and latitude are compared with other studies involving bryozoans. The literature on Antarctic benthic taxa, in general, is also considered to determine whether trends within the Bryozoa are reflected in other groups.
Seasonal development of algal biomass in snow-covered fast ice and the underlying platelet layer in the Weddell Sea, Antarctica
Authors: Günther Sven , Dieckmann Gerhard S.
Published: December 2007

The seasonal changes of the nutrient regime and the development of algal communities in snow-covered fast ice and the underlying platelet layer was investigated in the eastern Weddell Sea during autumn, winter, and spring 1995. In the upper sea ice, an autumnal diatom community became enclosed during subsequent ice growth in winter, declined, and was replaced by a flagellate dominated community in spring. In this layer, nitrate was completely exhausted at the end of spring, although nutrients had been partly regenerated in early spring. The progressive congelation of platelet ice contributed significantly to sea ice growth thus influencing algal inoculation of the sea ice bottom. Biomass, present in the uppermost section of the platelet layer, could be found in the sea ice bottom after this section congealed to solid ice. After incorporation, species composition changed from larger and chain-forming species to species of smaller cell size. Concurrently, net growth rate slowed down from 0.07 day−1 within the platelet layer to 0.03 day−1 within the sea ice. Despite a thick snow cover of more than 20 cm, maximum biomass yield was 210 mg chl a m−2 in the platelet layer and 40 mg chl a m−2 in the sea ice respectively, while 95% of the latter was located within consolidated platelet ice. Total fast ice biomass observed here is significantly lower than that observed in snow-free fast ice of the Ross Sea, but because snow cover of the southern Weddell Sea is representative of most fast ice areas in the Antarctic, the data presented here are of general value.
Necrophagous lysianassoid Amphipoda in the diet of Antarctic tern at King George Island, Antarctica
Authors: Jażdżewski Krzysztof , Konopacka Alicja
Published: December 2007

Amphipod crustaceans constituted 30% of the food biomass from the stomachs of Antarctic tern (Sterna vittata) captured at King George Island in three consecutive seasons. Five species of lysianassoid amphipods occurred in the material: Abyssorchomene plebs, Cheirimedon femoratus, Hippomedon kergueleni, Waldeckia obesa and Orchomenella rotundifrons. All these amphipods are known as necrophages inhabiting the upper and middle sublittoral of western Antarctic. They are commonly caught in masses in baited traps, but never occur in the littoral zone or in tidal pools. It is suggested that the source of the amphipod diet of S. vittata are seal or penguin carcasses and dead fish brought by waves to the tidal zone, serving as a bait for necrophagous amphipod crustaceans when submerged in water before stranding on the beach.
Possible evidence for Late Cretaceous off-axis volcanism in the outer James Ross Basin
Authors: Lomas Simon A. , Dingle Richard V.
Published: December 2007

A prominent volcaniclastic channel sandstone deposited by a landward-flowing sediment gravity flow is described from the Maastrichtian of Snow Hill Island in the northern Larsen Basin. The characteristics of this petrographically distinct event deposit appear to indicate a volcanic source to the east of Snow Hill Island, well away from the magmatic arc landmass which sourced the bulk of the Larsen Basin fill, suggesting minor off-axis intrabasinal volcanism in Maastrichtian to Paleogene times.
Volcanic ash bands in the Frontier Mountain and Lichen Hills blue-ice fields, northern Victoria Land
Authors: Perchiazzi Natale , Folco Luigi , Mellini Marcello
Published: December 2007

Dust bands in the blue-ice of the Frontier Mountain meteorite trap (northern Victoria Land, Antarctica) were previously reported as upthrust basal debris. Four of them have now been sampled at Frontier Mountain and Lichen Hills. The absence of local rocks and sedimentary fragments, the ubiquitous abundant volcanic glass with no evidence for abrasion, the igneous minerals, the chemical compositions of glass and minerals and the bulk chemical compositions indicate that they are volcanic ash bands (tephra) and not glacial debris. Although hardly distinguishable in the field, the different volcanic ash bands are discriminated using mineralogical and chemical data, as well as particle size, abundance and vesicularity of glass. Chronological constraints, particle size and chemical compositions localize the source for the Frontier Mountain and Lichen Hills tephra within the recent activity of the Mount Melbourne Volcanic Province in northern Victoria Land; possible emission centres are the Pleiades (40 ± 50 ka to 3 ± 14 ka) and/or Mount Rittmann (3.97 Ma to present).
Lithostratigraphy of Miocene–Recent, alkaline volcanic fields in the Antarctic Peninsula and eastern Ellsworth Land
Authors: Smellie J.L.
Published: December 2007

Miocene–Recent alkaline volcanic rocks form numerous outcrops scattered widely throughout the Antarctic Peninsula and eastern Ellsworth Land. They occur mainly as short-lived (typically 1–2 million years) monogenetic volcanic fields but include a large outcrop area in northern Antarctic Peninsula which includes several substantial polygenetic shield volcanoes that were erupted over a 10 million year period (the James Ross Island Volcanic Group (JRIVG)). As a whole, the outcrops are of considerable importance for our understanding of the kinematic, petrological and palaeoenvironmental evolution of the region during the late Cenozoic. Until now, there has been no formal stratigraphical framework for the volcanism. Knowledge of the polygenetic JRIVG is still relatively poor, whereas a unifying lithostratigraphy is now possible for the monogenetic volcanic fields. For the latter, two new volcanic groups and twelve formations are defined, together with descriptions of the type sections. The volcanic fields (both polygenetic and monogenetic) vary in area from c. 1 to 4500 km2, and aeromagnetic data suggest that one may exceed 7 000 km2. The rocks are divisible into two contrasting petrological ‘series’, comprising basanites–phonotephrites and alkali basalts–tholeiites. The JRIVG is dominated by alkali basalts–tholeiites but also contains rare basanites, and phonotephrite–tephriphonolite compositions occur in minor pegmatitic segregations in sills. By contrast, in the monogenetic volcanic fields, basanites–phonotephrites generally form the older outcrops (mainly 15–5.4 Ma) and alkali basalts–tholeiites the younger outcrops (4(?)–<1 Ma). Throughout the region, erupted volumes of alkali basalts–tholeiites were an order of magnitude greater, at least, than those of basanite–phonotephrite compositions. Interpretation of the lithofacies indicates varied Miocene–Recent palaeoenvironments, including eruption and deposition in a marine setting, and beneath Alpine valley glaciers and ice sheets. Former ice sheets several hundred metres thick, and fluctuating ice surface elevations, which were generally higher during the eruptive periods than at present, can also be demonstrated.
Assessing importance and value
Authors: Walton David W.H.
Published: December 2007

Efficiency, effectiveness, value for money, importance - these seem to be the mantras of the present age. They are applied to all areas of human activity, including science, yet finding scientifically robust and independent methods of assessing them is difficult. In science how can we show that one group is more effective than another, that the ideas of one individual are more important than those of others, that money invested in one type of research provides better value than in another? In industry the success of most research is measured in new products and profits. But for blue-skies research whose outputs are papers in the scientific literature, the IS1 Citation Index and its various derivatives is still the principal quantitative method used. Its inadequacies for assessments have been detailed - wrong names, linked groups, variable half lives for different subjects, over citation of review and method papers etc. Yet, such is the simplicity ofthe system, many still use the citation value to decide on the destination of their next submission or the value of previously published material.
Genesis, properties and sensitivity of Antarctic Gelisols
Authors: Beyer L. , Bockheim J.G. , Campbell I.B. , Claridge G.G.C.
Published: December 2007

According to the newest version of the US Soil Taxonomy permafrost-affected soils are Gelisols. Antarctic Gelisols in the cold deserts of the Ross Sea sector are formed under extreme conditions of low temperature and aridity. The main soil forming processes are oxidation and salinization, with almost complete absence of organic matter. The oldest soils date from around 13 Ma. The origin of most soil salts is atmospheric, linking these soils to those in other parts of the world through atmospheric processes. The soils have water contents in the active layer of the most arid areas <1%. With decreasing latitude or proximity to the coast in East Antarctica and the Antarctic Peninsula, soil water contents increase and the soils support a range of soil organisms and plant species. At latitudes ≤66°S organic matter accumulation and several other pedogenic processes such as cryoturbation, mineral weathering, brunification, acidification, podzolization and redoximorphism occur. In addition, these soils receive nitrogen and phosphorus from seabirds. In most places summer thaw lasts little more than six weeks; thaw depths range from around 10–100 cm. A critical factor in the soil development is the albedo of the soil surface, since the absorbed energy controls weathering processes. The extreme fragility of the soils in the arid Ross Sea sector is largely due to the absence of structure, cohesion, moisture and organic materials. Recovery from physical human disturbances is in the order of hundreds to thousands of years. In East Antarctica and the Antarctic Peninsula plant and organisms growth is similarly slow and ecosystems are susceptible to human impact. The occurrence of many old soils at high inland elevation indicates that little response to global climatic change would be expected there. For the much younger soils in East Antarctica and the Antarctic Peninsula, when mean annual summer temperatures are higher, responses to global change and change in sea level may be significant.
Growth and age of the Antarctic bryozoan Cellaria incula on the Weddell Sea shelf
Authors: Brey Thomas , Gerdes Dieter , Gutt Julian , Mackensen Andreas , Starmans Andreas
Published: December 2007

We analysed growth of the arborescent Antarctic cheilostome bryozoan Cellaria incula by stable carbon and oxygen isotope analysis. The growth of one complete branch of C. incula takes one year, i.e. owing to the bifurcate colony structure two new branches grow from each branch of the previous generation. The maximum age of a C. incula colony is likely to be more than 14 years. Annual production-to-biomass ratio is 0.67, the highest value hitherto measured for any benthic invertebrate south of 62°S. Comparatively fast growth and high productivity identify C. incula as a pioneer species which is able to quickly occupy spatial niches produced by iceberg scouring on the Antarctic shelf.
Meiofaunal assemblages associated with scallop beds (Adamussium colbecki) in the coastal sediments of Terra Nova Bay (Ross Sea, Antarctica)
Authors: Danovaro Roberto , Pusceddu Antonio , Mirto Simone , Fabiano Mauro
Published: December 2007

Meiofaunal community structure in coastal sediments of Terra Nova Bay (Ross Sea) was related to quantity and biochemical composition of sedimentary organic matter. The sediments were generally characterized by large amounts of chloropigments and labile compounds (dominated by proteins), indicating high inputs of primary organic matter. Meiofaunal densities were very high and comparable to those from the most productive areas worldwide. Sediments with high densities of the scallop had low meiofaunal densities especially in the top 2 cm, suggesting that scallop clapping contributed to meiofauna resuspension. However, it is not possible to exclude the probability that meiofauna are part of the scallop beds apparently have an important role in structuring meiofaunal communities with nematodes dominant where Adamussium colbecki is absent, and gastrotrichs dominant (44–51%) in A. colbecki beds, reaching the highest density reported so far.
Petroleum hydrocarbons ten years after spillage at a helipad in Bunger Hills, East Antarctica
Authors: Gore D.B. , Revill A.T. , Guille D.
Published: December 2007

Surface and subsurface sediments from a helipad in Bunger Hills were collected ten years after accidental contamination with a small quantity (probably < 10 litres) of petroleum products. The contaminants are dominated by Jet A2 synthetic lubricating oil which exhibits no evidence of degradation or environmental mobility. In contrast, Jet A1 turbine kerosene is less abundant at the surface than at 20 cm depth. There is no evidence for biodegradation of the Jet A1 in the subsurface sample, suggesting that kerosene is environmentally mobile in the surface sediments.
Post Permian tectono-thermal evolution of western Dronning Maud Land, East Antarctica: an apatite fission-track approach
Authors: Jacobs Joachim , Lisker Frank
Published: December 2007

New apatite fission-track (AFT) ages from Heimefrontfjella and Mannefallknausane indicate that the Mesoproterozoic basement and Permian sedimentary cover rocks were heated to c. 100°C during the Mesozoic. Heating was due to the burial by up to 2000 m of Jurassic lavas at c. 180 Ma, when the area was affected by the Bouvet/Karoo hot spot. Near the developing coastline, the lava pile was quickly eroded and in part deposited on the continental shelf as pebbly and coarse-grained volcaniclastic sandstones. The AFT data indicate that farther inland the lava pile was not eroded until c. 100 Ma, and the Palaeozoic unconformity between the Mesoproterozoic basement and Permo–Carboniferous sedimentary rocks as a reference plane remained at temperatures of c. 80°C. Formation of an up to 800 m b.s.l. deep graben in from Heimefrontfjella as well as flexural uplift and rapid denudational cooling of the not extended crust from Heimefrontfjella southwards occurred at c. 100 Ma. It is speculated that a period of major plate reorganisation and new rifting at c. 100 Ma is responsible for affecting a much wider continental margin as far inland as Heimefrontfjella and producing a total relief in excess of 3500 m.
Ecohydrological response to a geomorphically significant flood event in a semiarid catchment with contrasting ecosystems
Authors: Gutiérrez‐Jurado Hugo A. , Vivoni Enrique R. , Istanbulluoglu Erkan , Bras Rafael L.
Published: December 2007

Climate and topographic conditions in a first‐order semiarid catchment in central New Mexico have given rise to opposing hillslopes characterized by different soil profile, vegetation and landform characteristics. In this study, we present the differential response of these two hillslope ecosystems to a geomorphically significant (GS) flood event based upon field observations of rainfall, soil moisture and peak channel discharge. We illustrate the role played by slope position, soil properties and vegetation on soil moisture dynamics and runoff production. Furthermore, we document observed geomorphic changes in the opposing slopes. Analysis of the hillslope and channel response to this exceptional event provides insights on the terrain‐soil‐vegetation interactions acting on the movement of water and sediments through the semiarid system.
An investigation of regional tectonic strain on water levels in Devils Hole, Death Valley National Park, Nevada
Authors: Robertson G. D. , Ge S. , Cutillo P. A.
Published: December 2007

Changes in hydraulic head at Devils Hole due to regional tectonic deformation were estimated using aquifer properties and the volumetric strain field present through the Great Basin in the western United States. Devils Hole is a large fault cavern located along a 15 km spring discharge line in a carbonate‐rock aquifer, 240 km west of Las Vegas, Nevada. Geodetic measurements indicate that extensional strain in the Devils Hole area is oriented N 65 W and has a rate of 8 nanostrain/yr. Changes in hydraulic head due to strain were calculated and then used as initial conditions in a calibrated numerical ground‐water flow model. Results of this analysis show that tectonic deformation could produce up to 0.02 cm/yr of water‐level decline in Devils Hole. However, this rate is relatively small in comparison to rates caused from other factors such as natural recharge and ground‐water pumping.
Lengthening plus shortening of river‐to‐lake connection times in the Mackenzie River Delta respectively via two global change mechanisms along the arctic coast
Authors: Lesack Lance F. W. , Marsh Philip
Published: December 2007

River deltas along the circumpolar arctic coast are lake‐rich and poorly understood ecosystems, set in a region expected to change rapidly. Over the past 30+ years annual river‐to‐lake connection times in the Mackenzie Delta have lengthened (>30 days) in the lowest elevation lakes and may have shortened in the highest elevation lakes, respectively via sea level rise and declining effects of river‐ice breakup. Lengthened connection times indicate summer low‐water levels in the delta have increased by an amount (0.3 m) equivalent to three times local sea level rise (0.1 m) over the same period. Such an amplification effect of recent sea level rise has been completely unexpected and may be a result of enhanced storm surges in response to receding arctic sea ice or coastal backwater effects on the river flow. Shortened connection times are consistent with other work showing a decline in river‐ice breakup effects, an important control on annual peak water levels.