bluuebunny/crossref_metadata_2025 huggingface dataset:
The diet of Antarctic fur seals (Arctocephalus gazella Peters 1875) during winter at South Georgia
Authors: Reid Keith
Published: December 2007

The diet of mainly adult and sub-adult male Antarctic fur seals (Arctocephalus gazella) was investigated during the austral winters of 1992 and 1993 using faecal (scat) analysis. Of samples containing identifiable prey remains (n = 376), c. 28% contained krill alone, c. 37% contained fish alone and c. 35% contained both krill and fish. The mean size of krill taken was smaller than in summer due to the absence of large adult krill of 55–60 mm total length. Of the 25 fish taxa taken, krill-feeding species predominated, especially in scats that also contained krill. Non-krill feeding species were more abundant in scats containing fish alone. The mackerel icefish (Champsocephalus gunnari Lönnberg 1905), which feeds mainly on krill, was the most important fish species in terms of absolute frequency (53%), frequency of occurrence (69%) and estimated biomass (47%); fur seals may have a significant impact on local stocks of this species. Cephalopods and pelagic fish (myctophids) were of minor importance in the diet (<2%). The importance of krill and krill-feeding fish species suggests that the male fur seals, which are present around South Georgia in winter, are targeting their foraging on a krill and fish community, probably associated with krill aggregations.
Ecophysiological investigations of Usnea antarctica in the maritime Antarctic I. Annual microclimatic conditions and potential primary production
Authors: Schroeter Burkhard , Olech M. , Kappen L. , Heitland W.
Published: December 2007

Photosynthetic photon flux density (PPFD), air relative humidity and thallus temperature (TT) were measured in Usnea antarctica over a period of 12 months at a coastal rock on King George Island, South Shetland Islands. TT had an annual amplitude of c. 54 K with the maximum of +27.4°C recorded in December and minimum of −27.3°C in July. Daily maximum TT exceeded 0°C every month except in June and July when they were below −0.4°C and −1.6°C, respectively. Daily minimum temperatures were always below zero. Diel courses of PPFD showed pronounced seasonal differences between summer (more than 2000 μmol m−2s−1) and winter (less than 50 μmol m−2s−1 in July). Daily sum of PPFD was highest (more than 30 mol m−2d−1) in December and lowest (0.1 mol m−2d−1) in July. A photosynthesis model was used to estimate the potential annual primary production from habitat PPFD and TT. The estimated potential annual carbon balance of U. antarctica was 323 mg CO2 g−1 dry weight y−1 assuming that the lichen was always at optimal moisture. The potential carbon balance indicates that primary production is severely limited by low PPFD and subzero TT in the austral winter. Nevertheless, the PPFD and TT would allow metabolic activity during winter but with a negative carbon balance during May–August. Spring and autumnal months are revealed as probably the most important periods for lichen primary production because PPFD exceeds photosynthetic light compensation point during the daytime and ambient moisture conditions frequently favour a positive carbon balance.
Geochronology of Cretaceous granites and metasedimentary basement on Edward VII Peninsula, Marie Byrd Land, West Antarctica
Authors: Adams C.J. , Seward D. , Weaver S.D.
Published: December 2007

Rb-Sr ages of Swanson Formation on Edward VII Peninsula, West Antarctica, indicate a late Ordovician age, 421–432 Ma for regional metamorphism. K-Ar ages of 113–440 Ma, reflect a second thermal metamorphism during emplacement of widespread Cretaceous granites. Rb-Sr ages of five monzogranite/syenogranitic plutons of Byrd Coast Granite are in the range 95–105 Ma (initial 87Sr/86Sr ratios 0.710–0.715) and represent stages of crystallization of anorogenic granite (A subtype). These correlate with Byrd Coast Granite (100–110 Ma) farther east in Marie Byrd Land, and with Cretaceous granitoids on the Campbell Plateau and in southern New Zealand. K-Ar mica/hornblende and fission-track apatite/zircon ages indicate that regional cooling began c. 90–100 M.y. ago immediately after granite emplacement. Uplift continued throughout the peninsula during the period 55–100 Ma (late Cretaceous-early Tertiary), associated with regional uplift in the rift-drift stages of Gondwana break-up at the South-west Pacific spreading centre. Apatite fission track ages show that during late Cretaceous-early Tertiary time the peninsula behaved as two blocks. The Alexandra Mountains were exhumed 20 m.y. before the Rockefeller Mountains and are possibly separated by a fault active initially in the mid-Cretaceous or earlier, and later reactivated in the late Cretaceous-early Tertiary. An averaged uplift rate (50–100 Ma) of 0.025 mm yr−1 is characteristic of the inferred intraplate tectonic setting.
A new Eocene crab (Crustacea, Decapoda) from Seymour Island, Antarctica
Authors: Aguirre-Urreta María B. , Marenssi Sergio , Santillana Sergio
Published: December 2007

A new xanthid crab, Tumidocarcinus foersteri n. sp. is described from the La Meseta Formation on Seymour Island, Antarctica. The fossils were obtained from the Allomember Submeseta of Late Eocene age. As other representatives of the genus Tumidocarcinus were only known from New Zealand and Australia, this finding provides new insights on the palaeobiogeography of high latitude faunas during the Early Tertiary.
Retrogressive fluids and vein formation during uplift of the Priestley metamorphic complex, north Victoria Land, Antarctica
Authors: Craw D. , Cook Y.A.
Published: December 2007

The poly-deformed Priestley schist (Wilson Terrane) of north Victoria Land, Antarctica ranges in metamorphic grade from lower greenschist facies to upper amphibolite facies. All grades of schist have been affected by structurally controlled retrogressive H2O-CO2 fluids with 45–70 mole % CO2. The fluids have deposited quartz-carbonate veins with pyrite and chlorite or biotite in late stage structures. Veins typically constitute < 1% of the rock mass, but in one greenschist facies area > 10% of the rock is vein. Veins in higher grade schists have been boudinaged after formation, and many have been annealed. Primary fluid inclusions are preserved in veins in biotite zone schists in two localities. At one locality, entrapment of immiscible fluids (water with c. 8 and 45 mole % CO2) occurred during vein formation, at about 280–300°C and 700 ± 200 bars fluid pressure. The aqueous fluid is slightly saline (4 wt % NaCl equivalent). At the other primary fluid inclusion locality, veins were formed from a single phase fluid (c. 70 mole % CO2) at 200–350°C and 1600 ± 500 bars fluid pressure. Both these vein systems are inferred to have formed between 2 and 8 km depth, near the brittle-ductile transition. Retrogressive fluid mobility and vein formation occurred throughout schist in the Priestly metamorphic complex during uplift in the latter part of the Ross Orogeny (c. 490 Ma), following near-isobaric cooling at metamorphic depths.
Jurassic titaniferous ironstone in a Devonian host: Pivot Coal Measures expunged
Authors: Woolfe Ken J. , Arnot Malcolm J. , Bradley Graham M.
Published: December 2007

The Devonian, Pivot Coal Measures in southern Victoria Land are non-carbonaceous. The sequence contains bedding parallel, titaniferous ironstones up to 50 cm thick, but no coal or carbonaceous shale, the unit is consequently renamed Pivot Member of the Arena Sandstone. The more Fe-Ti oxide-rich (up to 40 modal %) beds appear black and coal-like with conchoidal fracture and closely spaced cleat-like fractures. The coal-like beds grade laterally and vertically into less altered sedimentary rocks in which fine bedding-parallel concentrations of Fe-Ti oxide pick-out parting surfaces on ripples and other sedimentary structures. Thin section petrography shows that the Fe-Ti oxide is replacive, and outcrop relationships show that the replacement was related to dolerite intrusion 200 million years after the sedimentary host was deposited. Replacement of muscovite, biotite and chlorite by Fe-Ti-oxide occurred at 179 ± 3 Ma, at pressures of 0.3–0.4 kbar and at temperatures as low as 380°C.
A pilot study on the interactions between katabatic winds and polynyas at the Adélie Coast, eastern Antarctica
Authors: Adolphs Ute , Wendler Gerd
Published: December 2007

Infrared satellite images of the coastal area off Adélie Land were examined together with two wind data sets, one from the manned French station, Dumont d'Urville, the other one from an Automatic Weather Station (AWS) during the 1986 austral winter. A correlation between the development of open water areas (polynyas) and the appearance of extremely strong offshore winds can be drawn. The wind direction tended to be more perpendicular to the coastline during these extreme ‘events’, suggesting a katabatic origin of the increase in wind strength. In the study area the influence of the katabatic wind on the sea ice extends 20–100 km offshore. Sea ice motion further off the coast seems to be more dominated by synoptic scale weather systems. Broader scale atmospheric influences may create large polynya structures which influence the development of coastal winds, as the temperature contrast between open water and the cold continent generates its own circulation. Strong wind events can have a weakening effect on the coastal sea ice which can lead to a much more sensitive reaction of the sea ice in response to following anomalous wind events.
The local surface energy balance of the Ecology Glacier, King George Island, Antarctica: measurements and modelling
Authors: Bintanja Richard
Published: December 2007

Meteorological measurements performed during the austral summer of 1990–91 are used to evaluate the surface energy balance and ablation at an elevation of 100 m asl on the Ecology Glacier, which is an outlet glacier of the main ice cap of King George Island, Antarctica. Strong, gusty westerly winds prevail, although occasional south-easterly winds from the Weddell Sea reach the island. Generally, the climate can be characterized as relatively warm and humid with mean summer temperatures well above 0°C. As a result, considerable ablation (0.75 m water equivalent per month) takes place in the lower parts of the Ecology Glacier. The surface energy balance and ablation are calculated using a model with input from meteorological data. In spite of the large amount of cloud (0.83), solar radiation provided most of the energy used for melting (70.3 W m−2). The longwave radiation, sensible heat flux and latent heat flux contributed −9.5, 27.4 and 7.4 W m−2 respectively. Calculations show that a temperature rise of 1°C increases the ablation by almost 15%. This indicates that the ice caps and glaciers currently present on the subantarctic islands and the Antarctic Peninsula may be quite sensitive to climate change.
The synoptic origins of precipitation over the Antarctic Peninsula
Authors: Turner J. , Lachlan-Cope T.A. , Thomas J.P. , Colwell S.R.
Published: December 2007

The synoptic origins of precipitation on the western side of the Antarctic Peninsula over the one year period March 1992 to February 1993 are investigated using meteorological observations, satellite imagery and analyses produced by the UK Meteorological Office. Precipitation at Rothera Station was found to occur at 30% of the synoptic reporting time with 80% of precipitation reports being associated with cyclonic disturbances. Although three quarters of all precipitation reports were for snow, the proximity of Rothera to the zone of maximum cyclonic activity meant that incursions of mild air produced rain in all seasons. During the year 95% of all precipitation was classed as slight. Variability of precipitation on the intraseasonal timescale was highly dependent on the synoptic-scale circulation. The most common synoptic situation for precipitation was a frontal cyclone over the Bellingshausen Sea which accounted for 38% of all precipitation events and 62% of the moderate and heavy precipitation reports. Of the extra-tropical cyclones that gave precipitation 49% were found to have developed south of 60°S. None of the precipitation at Rothera was attributable to mesocyclones. Snow stake measurements from Rothera were a poor indicator of precipitation as a result of blowing snow.
Time for concern: is the health of Antarctica's wildlife in danger?
Authors: Kerry Knowles , Clarke Judy
Published: December 2007

The high degree of isolation of Antarctica may well have protected its seals and birds from many of the diseases found in related species outside the continent. Our recent review of diseases in penguins has shown that birds taken into captivity are susceptible to a wide range of diseases, many of which have not been recorded in the wild. The same situation presumably applies to Antarctic seals. Adélie penguins in Antarctica have been shown to have antibodies to Newcastle disease virus, avian influenza virus and the Chlamydia group of bacteria. From this we could infer that wild birds have had contact with these diseases but, in the cases of viral diseases at least, a more likely explanation could be that the antibodies are the result of cross-infection with related but benign viral strains. There is no evidence to date that any major exotic diseases have been introduced into the Antarctic ecosystem. However, unless non-pathogenic strains are present to provide cross-immunity, all birds and seals are likely to be highly susceptible to such introductions.
Interpopulation relationships in two species of Antarctic fish Notothenia rossii and Champsocephalus gunnari from the Kerguelen Islands: an allozyme study
Authors: Duhamel Guy , Ozouf-Costaz Catherine , Cattaneo-Berrebi Ghislaine , Berrebi Patrick
Published: December 2007

Enzymatic polymorphism was used to detect variability within Notothenia rossii from two sites on the Kerguelen Plateau and Champsocephalus gunnari from the same sites and the South Orkney Islands. No polymorphism was found in the second species and it was low but not statistically significant in the first. This apparent homogeneity does not substantiate suggestions from other results that the populations can be separated, especially in the case of C. gunnari. Other approaches will be necessary to solve definitively the question of population separation.
Geomorphological and neotectonic features of Hurd Peninsula, Livingston Island, South Shetland Islands
Authors: Pallàs R. , Vilaplana J.M. , Sàbat F.
Published: December 2007

On Hurd Peninsula (Livingston Island) neotectonic features, such as faults, affect the landforms and emerged marine levels. A detailed local study of these features provides information on the recent structural and geomorphological evolution of the area. We suggest that Hurd Peninsula is divided into several tectonic blocks separated by faults. Movement of the faults determines the relative altitude of these blocks and, in consequence, their susceptibility to glacial, periglacial or marine processes. Although some of the tectonic movements reflected in the landforms may have been inherited from former phases of deformation, some of the neotectonic faulting has a maximum lower Miocene age. A new method of correlation of emerged beach levels is suggested and the possibility of analysing the effects of neotectonic deformations from their analysis is discussed. The application of the methods tested here to other areas of the South Shetland archipelago could provide insights into the timing and mechanisms of recent tectonic evolution.
An Eocene tardigrade (Mammalia, Xenarthra) from Seymour Island, West Antarctica
Authors: Vizcaíano Sergio F. , Scillato-Yané Gustavo J.
Published: December 2007

Carlini et al. (1990) reported the presence of Xenarthra (Mammalia) from the Eocene deposits of Seymour Island, Antarctic Peninsula, based on an ungual phalanx from locality RV 8200. The locality, referred to informally as “mammal site” by Woodburne & Zinsmeister (1984), is located at 64°14′21″S, 56°39′44″W at an elevation of 45 m in the middle levels of the shallow marine La Meseta Formation (TELM 5 of Saddler 1988). Carlini et al. (1990) initially identified the phalanx as a megatherioid sloth (Order Tardigrada). Marenssi et al. (1994) revised its identification to ?Tardigrada or ?Vermilingua, by comparison with a primitive myrmecophagid (Order Vermilingua) from the Lower Miocene of Patagonia, whose ungual phalanges are indistinguishable from those of primitive sloths (Carlini et al. 1992). We report a fragmentary tooth of a member of the Tardigrada (Family incertue sedis) confirming the presence of this group in the Eocene of Antarctica.
Synoptic forcing of wind and temperature in a large cirque 300 km from the coast of East Antarctica
Authors: Jonsson Stig
Published: December 2007

Between 18 January 1988 and 3 June 1989, an automatic weather station recorded 13 different weather parameters every 3 h on a blue-ice area located in Scharffenbergbotnen, a large cirque in central Heimefrontfjella 300 km from the Weddell Sea coast. The first part of the paper reports on annual and monthly data regarding air temperature, air pressure, wind speed and wind direction, and a comparison is also made with corresponding data from the Neumayer and Halley stations. The second part deals mainly with winter (i.e. April–September) conditions in Scharffenbergbotnen. They seem, at least during 1988–89, to have been characterized by a large-scale (30–40 days) and, superimposed on the large-scale, a small-scale (3–4 days) co-variation of air temperature, air pressure and wind speed. The large-scale variation was earlier found to be synoptically forced. This paper shows that synoptic forcing exists also on smaller time scales. Pools of cold, stagnant air are regularly formed in the cirque only to be blown away by katabatic winds triggered by small variations in the synoptic pressure field. When this happens the air temperature increases by more than 20°C and the wind direction swings from east towards south-east. When low pressures dominate in the eastern part of the Weddell Sea, the katabatic winds become very strong, but weaker wind pulses also take place when the synoptic pressure gradient is directed towards the north-east. It therefore seems as if these very regular katabatic events are forced both by synoptic-scale pressure gradients and gradients due to the sloped inversion.
Aspects of the biogeochemistry of sulphur in glacial melt water ponds on the McMurdo Ice Shelf, Antarctica
Authors: De Mora S.J. , Lee P.A. , Grout A. , Schall C. , Heumann K.G.
Published: December 2007

The distribution of dimethylsulphide (DMS), together with the precursor dimethylsulphonio-propionate (DMSP) and the oxidation product dimethylsulphoxide (DMSO), was measured in melt waters on the McMurdo Ice Shelf in the immediate vicinity of Bratina Island. Conductivity in these sulphate dominated ponds was extremely variable, ranging from 0.106–52.3 mS cm−1. Similarly, chlorophyll a concentrations in the pond waters (1–150 μg 1−1) and mats (1.4–33 μg cm−2) differed considerably. The biomass was dominated by benthic felts of phototrophic cyanobacteria, which might act as a source of biogenic sulphur compounds in the ponds. The mean (and ranges) of concentrations of dissolved sulphur compounds (nmol 1−1) were: CS2 0.16 (<0.04–1.29); DMSPd 0.6 (<0.07–8.4); DMS 3.5 (<0.07–183); DMSO 27.9 (15.5–184.5). Very high concentrations of DMSO were ubiquitous in the ponds in the ice-cored moraine region of the ice shelf, with dissolved concentrations having been 1–2 orders of magnitude greater than those of DMS or DMSPd. It is difficult to ascribe the formation of DMSO solely to the conventionally accepted pathways of DMS oxidation by either bacterial activity or photochemical reactions. A direct biosynthetic production from phytoplankton or bacteria might be involved which means that DMSO in aquatic environments could act as a significant source of DMS rather than as a sink as generally supposed.
Population differentiation by size for 0-age-class Champsocephalus gunnari at Shag Rocks and South Georgia, CCAMLR subarea 48.3
Authors: North A.W.
Published: December 2007

In 1991 Chamsocephalus gunnari <1 year old were sampled at Shag Rocks on 18 January and off five bays on the north-east coast of South Georgia between 19 January and 12 February. Two separate size-groups of 31–46 mm and 55–87mm standard length (SL) were found at Shag Rocks. However, samples taken off Possession Bay, South Georgia, within two days of those at Shag Rocks, contained only one size-group of 25–57 mm SL. Samples taken at other locations at South Georgia also contained only single size-groups between 24–63 mm SL. The mean and median length of the large size-group at Shag Rocks are significantly larger (P<0.001) than those at South Georgia. For those at South Georgia there was an apparent growth of around 0.76% SL d−1, which is comparable with previous reports of their growth rate during the first year. Based on this growth rate, the differences between the average size of the larger size-group of C. gunnari at Shag Rocks and those at South Georgia indicates that they hatched at periods separated by about three months. This and other published evidence suggests there may be separate populations of C. gunnari at Shag Rocks and South Georgia.
The food and energy intake rates of adult emperor penguins (Aptenodytes forsteri) rearing chicks
Authors: Robertson Graham , Newgrain Keith
Published: December 2007

The food and energy requirements of adult emperor penguins parenting chicks were examined at Auster (about 11 000 pairs) and Taylor Glacier (about 2900 pairs) colonies during the winter, spring and summer of 1988. Tritiated water-derived estimates of food consumption trebled during the five-month period of chick care, ranging from 2.3 kg d−1 in winter when chicks were <5% of adult mass, to 6.3 kg d−1 in summer, when chicks represented 40–50% of adult mass. These food consumption rates were equivalent to the acquisition of 11.4 MJ d−1 and 33.4 MJ d−1 metabolizable energy in winter and summer respectively. Chick provisioning was not accompanied by a major increase in food consumption by adults. Adults assimilated 84–92% of their daily food intake themselves and retained the remainder for the chick. The food ration of chick for the three seasons (42 kg) constituted only about 9.5% of adult maintenance requirements during the same period. Adults consumed an estimated 482 kg of food (including the ration for the chick), which amounted to about 10 700 t and 2800 t of fish and squid consumed by the breeding populations at Auster and Taylor Glacier, respectively.
Evidence for regional climate change in the recent evolution of a high latitude pro-glacial lake
Authors: Webster Jenny , Hawes Ian , Downes Malcolm , Timperley Michael , Howard-Williams Clive
Published: December 2007

Lake Wilson, a perennially ice-capped, deep (>100 m) lake at 80°S in southern Victoria Land was investigated in January 1993. Water chemistry and physical structure showed three distinct layers; an upper c. 35 m mixed layer of low salinity, moderately turbid water; a less turbid mid layer, 20 m thick of slightly higher salinity and supersaturated with oxygen; and a deep 20 m brackish layer (conductivity c. 4000 μS cm−1) with anoxic conditions in the lower 5 m. Extreme supersaturation of N2O (up to 400 times air saturation) together with high nitrate concentration (4000 mg m−3) was recorded in the deep layer. Phytoplankton biomass and photosynthetic activity was confined to the upper mixed layer and the band of supersaturated dissolved oxygen located at 40–55 m appears to represent a relict layer from when the lake level was lower. The evidence from a comparison of profiles between 1975 and 1993 suggests that Lake Wilson has risen 25 m since 1975, synchronous with a period of lake level rise in the McMurdo Dry Valleys lakes to the north at 77°S. Geochemical diffusion models indicate that Lake Wilson had evaporated to a smaller brine lake about 1000 yrs BP, which also fits the pattern shown by the McMurdo Dry Valleys lakes. Climate changes influencing lake levels have thus covered a wide area of southern Victoria Land.
Composition, distribution and origin of surficial salts in the Vestfold Hills, East Antarctica
Authors: Gore Damian B. , Creagh D.C. , Burgess J.S. , Colhoun E.A. , Spate A.P. , Baird A.S.
Published: December 2007

A regional chemical boundary termed the ‘salt line’, in the Vestfold Hills of East Antarctica, has been investigated using X-ray diffraction and electron probe analyses of surficial salts, and conductivity of surficial sediments. West of the salt line, halite and thenardite are abundant. These salts are derived from dispersal of marine aerosols, saturation of sediment by seawater during postglacial marine transgression, and glacial dispersal of salt-saturated fjord bottom sediments. East of the salt line, subglacial calcium carbonates and salts formed by chemical weathering of their substrates occur. Chemically and morphologically diverse minerals form the weathering products. They include two minerals not found previously in Antarctica, dypingite and hydromagnesite, and the first confirmed occurrence of brushite.
Geochemistry and origin of Mesoproterozoic metavolcanic rocks from Fisher Massif, Prince Charles Mountains, East Antarctica
Authors: Mikhalsky E. V. , Sheraton J. W. , Laiba A. A. , Beliatsky B. V.
Published: December 2007

Fisher Massif consists of Mesoproterozoic (c. 1300 Ma) lower amphibolite-facies metavolcanic rocks and associated metasediments, intruded by a variety of subvolcanic and plutonic bodies (gabbro to granite). It differs in both composition and metamorphic grade from the rest of the northern Prince Charles Mountains, which were metamorphosed to granulite facies about 1000 m.y. ago. The metavolcanic rocks consist mainly of basalt, but basaltic andesite, andesite, and more felsic rocks (dacite, rhyodacite, and rhyolite) are also common. Most of the basaltic rocks have compositions similar to low-K island arc tholeiites, but some are relatively Nb-rich and more akin to P-MORB. Intermediate to felsic medium to high-K volcanic rocks, which appear to postdate the basaltic succession, have calc-alkaline affinities and probably include a significant crustal component. On the present data, an active continental margin with associated island arc was the most likely tectonic setting for generation of the Fisher Massif volcanic rocks.
Preliminary investigation of the thermal biosystem of Mount Rittmann fumaroles (northern Victoria Land, Antarctica)
Authors: Bargagli R. , Broady P.A. , Walton D.W.H.
Published: December 2007

The biota and environment of fumarolic ground recently discovered near Mount Rittmann are described. Three patches (about 1 m2 each) of the moss Pohlia nutans were found in a minor caldera rim. Cyanophytes, chlorophytes, protozoa and bacteria were isolated from the moss and warm ground (30–50°C). The results are compared with those of previous studies on Antarctic volcanoes. The origin of the geothermal flora is discussed in terms of long-distance transport of propagules to the continent.
Reproduction of Antarctic flowering plants
Authors: Convey Peter
Published: December 2007

Reproductive allocation (reproductive biomass relative to vegetative biomass) and seed production were measured for samples of the two native phanerogams occurring in Antarctica. Material collected on South Georgia (subantarctic), Signy Island (northern maritime Antarctic) and Léonie Island (southern maritime Antarctic) allowed an initial comparison of reproduction over a wide latitudinal range. Sizes of vegetative and reproductive structures of Colobanthus quitensis were smaller in Signy Island samples than those from South Georgia or Léonie Island. This pattern was reflected in the pattern of seed production. Vegetative and reproductive structures of Deschampsia antarctica were generally similar in size at both maritime Antarctic sites, but larger at subantarctic South Georgia. Seed production was similar in each season assessed and at all three sites. In most samples of both species there were close relationships between reproductive and vegetative biomass, and seed output and reproductive biomass. Subantartic C. quitensis showed greater allocation to seed production than material from maritime Antarctic sites. D. antarctica showed the reverse pattern, with greater allocation to reproductive biomass and seed production in most samples of maritime Antarctic material, particularly those from Signy Island. Reproductive strategies do not form any specific adaptation to the Antarctic environment for these species. Reasons for the failure of other higher plants to become established in the maritime Antarctic are discussed, and it is concluded that geographical isolation is the main factor. The most important proximate factors influencing propagules which reach potential colonization sites are likely to be the short length and low temperature of the summer season in relation to the time required for establishment.
Ecology of diatom and bacterial assemblages in water associated with melting summer sea ice in the Weddell Sea, Antarctica
Authors: Gleitz Markus , Grossmann Sönnke , Scharekm Renate , Smetacek Victor
Published: December 2007

The fate of ice biota released via meltwater into pools of seawater trapped between melting ice floes (crack pools) was followed in late January in the southern Weddell Sea. Low salinity crack pools shared the following features: nitrate exhaustion, high pH and POC/PON ratios, high bacterial biomass composed of large cells, and a dense algal assemblage dominated to over 90% by only two diatom species. It is suggested that this “climax stage” evolved from a nutrient rich, moderate biomass situation prevailing in high salinity crack pools, and is representative of summer succession of sea ice biota. “Overflow” production following nitrate exhaustion by the algae resulted in internal (lipid) and external (presumably mucus) carbon pools. The latter must fuel bacterial biomass build-up, as algal mortality appeared to be low. The large algal and bacterial stocks point to low grazing pressure exerted by phagotrophic protists, presumably due to poor food quality (e.g. high C/N ratios) and/or excessive mucus production. It is concluded that environmental selection of the abundant ice algal species occurs under conditions prevailing in the disintegrating ice cover during summer, which differ drastically from those generally referred to as characteristic of the sea ice habitat at large (a combination of low temperature, low light and high salinity).
Fish in the diet of Antarctic fur seals (Arctocephalus gazella) at South Georgia during winter and spring
Authors: North A.W.
Published: December 2007

The occurrence of fish in the diet of the Antarctic fur seal (Arctocephalus gazella) at Bird Island, South Georgia was investigated by analysis of fish otoliths in scats (faeces) collected during late May to early November 1983. Of the 55 scats examined, 49 contained fish remains, and 45 contained fish otoliths. Ten fish species were represented by 415 otoliths, and 33 otoliths were too digested to be identified unequivocally. Fish size was estimated from otolith size based on published allometric equations. Four coastal notothenioid fishes dominated the fish component of the diet: Champsocephalus gunnari and Gobionotothen gibberifrons each comprised about 40% of the total fish mass; Chaenocephalus aceratus was ranked third by mass and the smaller Lepidonotothen larseni occurred in one quarter of the scats but was of lower importance in terms of mass. The length-frequency distribution of C. gunnari landed by the commercial fishery in October 1982 to June 1983 is similar to that which comprised the bulk of the diet in the present study. Compared with recent studies on the fish component of the diet in the literature, the dominance of C. gunnari is generally similar, however, there was a greater proportion of G. gibberifrons during the 1983 winter and spring than reported for recent winters.
Epilithic algae from a freshwater stream at Hope Bay, Antarctica
Authors: Pizarro Haydée , Izaguirre Irina , Tell Guillermo
Published: December 2007

Temporal and spatial variations of the epilithic phycoflora were studied in one of the largest streams at Hope Bay (Antarctic Peninsula) during the summer of 1992/93. A complete floristic inventory was made, and the relative frequencies of each algal taxon were estimated. Periphytic cumulative chlorophyll a was measured by means of artificial substrata. The stream was a typical maritime Antarctic lotic ecosystem, with evident signs of enrichment by sea-birds. Variability in discharge strongly affected the water chemistry, with the high water level periods characterized by the lowest conductivities and dissolved reactive phosphorus concentrations. Epilithic algal communities predominantly consisted of algal mats or filamentous and foliose forms of Prasiola crispa. Other dominant species were Leptolyngbya fragilis, Hydrurus foetidus, Chrysococcus cf. rufescens and Phaeogloea mucosa. Whereas P. crispa appeared more frequently near to the origin of the stream in Boeckella Lake, Chrysophyceae were better developed towards the mouth.
Reproduction in three species of fish from the Ross Sea and Mawson Sea
Authors: Vacchi M. , Williams R. , La Mesa M.
Published: December 2007

Reproductive characteristics are compared of the nototheniids Trematomus bernacchii and T. hansoni and the channichthyid Chionodraco hamatus caught in summer at Terra Nova Bay (Ross Sea) and caught all the year round in the waters off Casey Station (Mawson Sea). Whilst spawning of T. bernacchii took place in October–November off Casey and probably at Terra Nova Bay, the spawning period of T. hansoni differed between the sites (September–November off Casey, December–February at Terra Nova Bay). The spawning period also differed between sites for C. hamatus (August–October off Casey, December–February at Terra Nova Bay). Fecundity was higher and egg size was lower in nototheniid species (c, 8000 eggs of 3–4 mm) than in channichthyid (c. 4000 eggs of 4–5 mm). Moreover, the fecundity was lower and egg size higher in the specimens from Terra Nova Bay when compared to Casey.
Antarctic Peninsula granitoid petrogenesis: a case study from Mount Charity, north-eastern Palmer Land
Authors: Scarrow Jane H. , Pankhurst R.J. , Leat P.T. , Vaughan A.P.M.
Published: December 2007

At Mount Charity, north-eastern Palmer Land, Rb–Sr whole-rock dating has identified three successive phases of granitoid emplacement in Triassic (232 ± 4 Ma), Jurassic (168 ± 1 Ma), and Cretaceous (120 ± 4 Ma) times. The Triassic suite comprises tonalites, granodiorites (including one two-mica granodiorite), monzogranite and a granite having either I-type or S-like mineralogies. The Jurassic suite includes only S-like granites, and the Cretaceous biotite tonalites and biotite granodiorite are all I-type. The three suites have negative ∈Nd and positive ∈Sr, and have subtly different Nd and Sr isotope characteristics: Suite A, ∈Srt =+30 to +53 and ∈Ndt =−0.9 to −3.1, Suite B, ∈Srt =+43 to +64 and ∈Ndt =−2 to −5.3, Suite C, ∈Srt =+22 to +23 and ∈Ndt =−2.5 to −2.6. Mineralogical and compositional differences between the three suites suggest that different sources were tapped. All the granitoids are isotopically intermediate in composition between Palmer Land crust and depleted asthenosphere. We suggest that the I-type granitoids were produced by melting of meta-igneous crust; by contrast, the S-like granitoids represent partial melts of garnet-bearing sedimentary crust. Syn-magmatic structures in Suite A are compared with known structural events in western Palmer Land and suggest that extension controlled Triassic pluton emplacement. The Jurassic magmas were also emplaced during an episode of arc extension, and intrusion of the Cretaceous magmas was probably controlled by regional extension and dextral transtension. Successive phases of magmatism focussed at Mount Charity are consistent with reactivated faults acting as magma conduits.
Atmospheric surface pressure over the interior of Antarctica
Authors: Radok Uwe , Allison Ian , Wendler Gerd
Published: December 2007

Atmospheric surface pressures on the East Antarctic ice sheet are examined as a contribution to a new regional climatology based on automatic weather stations (AWS). Monthly mean pressures along two meridional AWS lines show near the coast a semi-annual oscillation with equinoctial minima, which become submerged inland under a larger annual oscillation, asymmetrically shaped around a summer solstice peak. Such a peak could arise when air surrounding the ice sheet is heated and enabled to spread out over the ice. This concept has provided a classical prediction of the ice sheet's mean elevation; in this paper the theory is expressed in a more modern form. After the summer “flood” the vertical tropospheric circulation driving the progressive katabatic surface layer drainage from the ice sheet should create relatively higher pressures below the convergence region over the ice sheet center and lower pressures near the coast. In fact the observed mean monthly surface pressures decrease with elevation more slowly than follows from substituting the observed mean temperature-elevation gradients (“topographical lapse rates”) in the hydrostatic equation. However, below the surface inversion along the sloping ice sheet surface the hydrostatic balance is shown to be governed by temperatures higher than observed at the surface. Hydrostatic pressures are calculated with climatic estimates of the inversion strength. Their differences from the observed monthly mean surface pressures represent non-hydrostatic residuals which can be added to pressures at the coast to form elevation-free (“sea level”) pressure profiles. These show both the expected coastal troughs and high pressure over an ice sheet summit (Dome C).
Antarctic environmental banking: the quest for a global approach
Authors: Caroli Sergio
Published: December 2007

Recent estimates report that more than eight million substances are known and that about 70 000 of them are widely exploited as pesticides, food additives, pharmaceuticals and industrial compounds with a total production of several million tons per year. The global circulation of polluting chemicals is well known to have reached even the Antarctic continent. This has resulted in an enhancement both of the baseline levels of naturally occurring organic and inorganic substances and an increasing presence of man-made compounds that simply should not be there. Localized anthropogenic activities are also contributing to the overall low yet progressive deterioration of the pristine Antarctic conditions. Local pollution may well be alleviated by a full implementation of the Madrid Protocol, but the crucial phenomena of worldwide chemical contamination will continue. To maximize the value of Antarctica as a source of global baseline data cooperative and harmonized approaches need to be adopted at the international level to monitor chemical pollution, thus avoiding useless duplication of effort and maximizing the comparability of data. From this standpoint the importance of the establishment of Antarctic environmental specimen banks cannot be exaggerated. The rationale behind such undertakings is certainly not new: specimen banks have been in operation for twenty years e.g. at the former National Bureau of Standards (now National Institute of Standards and Technology) in the USA, at the Swedish Museum of Natural History and at the Jülich Research Center in Germany.
The foraging behaviour and energetics of wandering albatrosses brooding chicks
Authors: Arnould J.P.Y , Briggs D.R. , Croxall J.P. , Prince P.A. , Wood A.G.
Published: December 2007

The energy expenditure of ten (five male, five female) wandering albatrosses (Diomedea exulans Linnaeus 1758) brooding chicks on Bird Island, South Georgia, was measured using doubly-labelled water. At-sea foraging behaviour was measured in the same individuals using satellite telemetry and leg-mounted activity recorders. Mean mass-specific daily energy expenditure was 341 kJ kg−1 day−1 during a mean of 4.12 days at sea and did not differ between the sexes. This is significantly lower than previously reported for the species and the lowest recorded for any albatross. There were no significant relationships between energy expenditure and the proportion of time spent flying (59.7%), distance flown (1448 km) or average speed (16.5 km h−1) suggesting that flying is not the most energetically expensive activity during foraging trips.
In situ photosynthesis and estimated annual production of the red macroalga Myriogramme mangini in relation to underwater irradiance at Signy Island (Antarctica)
Authors: Brouwer Patty E.M.
Published: December 2007

For the first time, photosynthesis of Myriogramme mangini (Gain) Skottsberg, one of the dominant red macroalgae in the sublittoral of Signy Island (South Orkney Islands), was studied in situ under natural irradiance levels in specially developed incubation chambers. M. mangini is adapted to low irradiance levels. Water transparency varied over the year. A maximum attenuation coefficient (kd) of 0.328 m−1 was reached in January, and the water was clearest in September with a kd value of 0.079 m−1. Classification of the water type on a Jerlov scale, gave water type 4 in January and II in May and June. The mean kd value over the year was 0.158 m−1 and the water was classified as Jerlov's water type 1. The euphotic depths (Zeu) for 1%, 0.1% and 0.01% surface irradiance levels were 29.1 m, 43.7 m and 58.3 m, respectively. Photosynthetic characteristics were determined, with the oxygen production rates and irradiance levels measured in situ, using P-I curves. The initial saturation irradiance (Ik) varied significantly from 18.0 ± 1.5 μmol m−2 s−1 in autumn to 10.5 ± 1.8 μmol m−2 s−1 in early spring. Mean photosynthetic capacity (Pg max) ranged from 57.2 ± 1.3 μmol O2 g−1DW h−1 to 63.1 ± 1.6 μmol O2 g−1DW h−1. The photosynthetic efficiency (α) was 3.2 ± 0.2 μmol O2 g−1DW h−1 (μmol m−2 s−1)−1 in autumn and 6.0 ± 1.0 μmol O2 g−1DW h−1 (μmol m−2 s−1)−1 in early spring. Compensation irradiance (Ic) was low and ranged from 2.5 to 2.8 μmol m−2 s−1. Estimates of annual net production rates were 128.1 and 0.6 mmol O2 g−1DW y−1 at 5 m depth and 20 m depth, respectively. A maximum depth of occurrence of M. mangini was predicted at 22.9 m (2.7% of the surface irradiance).
Egg-shell morphology of the Antarctic fish, Notothenia rossii Richardson, and the distribution and abundance of pelagic eggs at South Georgia
Authors: White Martin G. , Veit Richard R. , North Anthony W. , Robinson Ken
Published: December 2007

During winter research cruises to South Georgia (1983 and 1993) fish eggs were abundant in the neuston. Examination of the external sculpturing and the micropyle morphology of the eggs collected during 1993 using scanning electron microscopy indicated that these were fertilized ova of Notothenia rossii marmorata. A comparison between the eggs of N. rossii from Iles Kerguelen and South Georgia showed these to have a similar surface morphology but a difference in the structure of the micropyle. In 1993, the abundance of fish eggs in the neuston varied from 0-116 eggs m−3 with an average of 4.5 eggs m−3. During 1983, eggs were most abundant in the neuston but at lower average levels (0.04 eggs m−3, range 0–1.17 eggs m−3) and these were distributed from the surface to >380 m.
Acanthocephalan infection of inshore fishes at the South Orkney Islands
Authors: Zdzitowiecki Krzysztof , White Martin G.
Published: December 2007

An examination of notothenioid fish of three species, including 23 immature Notothenia coriiceps Richardson, revealed seven acanthocephalan species, including two Echinorhynchida occurring in the intestine and five Polymorphida in the body cavity. Four species -Metacanthocephalus johnstoni Zdzitowiecki, Corynosoma arctocephali Zdzitowiecki, C. pseudohamanni Zdzitowiecki, C.shackletoni Zdzitowiecki - are reported for the first time from the area. Polymorphida were twice as numerous as Echinorhynchida. The dominant parasites were Aspersentis megarhynchus (Linstow) and C. hamanni (Linstow) in Notothenia coriiceps, and C. bullosum (Linstow) in Chaenocephalus aceratus (Lönnberg). The infection of Notothenia coriiceps and Chaenocephalus aceratus in this area was compared with these species and Notothenia rossii Richardson in neighbouring areas. The infection of Notothenia coriiceps at the South Orkney Islands is more similar to that at the South Shetland Islands than that found at South Georgia.
Eclogite at the Antarctic palaeo-Pacific active margin of Gondwana (Lanterman Range, northern Victoria Land, Antarctica)
Authors: Ricci C.A. , Talarico F. , Palmeri R. , Vincenzo G. Di , Pertusati P.C.
Published: December 2007

Well-preserved eclogites were found for the first time in Antarctica, at the Lanterman Range, northern Victoria Land. They are part of a mafic–ultramafic belt that lies between the Wilson Terrane, representing part of the palaeo-Pacific margin of Gondwana, and the Bowers Terrane, a Cambro-Ordovician volcanic are and related sediments, accreted to the margin during the Ross Orogeny. The eclogites formed at temperatures in the range 750–850°C and pressures above 15 kbar and subsequently experienced a decompressional path to low pressure amphibolite facies conditions. The formation and exhumation of eclogites and the attainment of the metamorphic peak in adjacent rock units is consistent with a plate convergent setting model at the palaeo-Pacific margin of Gondwana.
An inventory of Antarctic sub-glacial lakes
Authors: Siegert M.J. , Dowdeswell J.A. , Gorman M.R. , McIntyre N.F.
Published: December 2007

An extensive analogue database of 60 MHz radio-echo sounding records of Antarctica (covering 50% of the ice sheet) is held at the Scott Polar Research Institute, University of Cambridge. This database was analysed in order to determine the presence and location of Antarctic sub-glacial lakes. In total, 77 sub-glacial lake-type records were identified, 13 more than detected in previous studies. An inventory of these sub-glacial lakes includes geographical coordinates, minimum length and overlying ice thickness for each lake. Information concerning the location of these lakes indicates that the majority (~70%) are found in the proximity of ice divides at Dome C and Ridge B within East Antarctica.
Climatology and implications for perennial lake ice occurrence at Bunger Hills Oasis, East Antarctica
Authors: Doran Peter T. , McKay C.P. , Meyer M.A. , Andersen D.T. , Wharton R.A. , Hastings J.T.
Published: December 2007

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