bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic palaeontology and biostratigraphy: are they “dated”?
Authors: Boucot Art
Published: December 2007

There is probably something buried deeply within the human genome that urges man to collect, sort, and classify. How else is it possible to explain a child's collection of matchbook covers or Mendeleev's periodic classification of the elements? Systematic palaeontology and biostratigraphy turn this natural urge to very practical purposes, for the geologist and the evolutionist are dependent on the results. However, anyone reading the pages of certain palaeobiological journals, or a certain type of article on extinction, might be forgiven for concluding that we now have reached the point where further systematic description of fossils and further refining of our biostratigraphic classification had reached the point of diminishing returns.
Jurassic–Tertiary stratigraphy and palynology of the James Ross Basin: review and introduction
Authors: Pirrie D. , Duane A.M. , Riding J.B.
Published: December 2007

A sedimentary sequence, c. 5–6 km thick, extending from the Kimmeridgian–Upper Eocene crops out in the James Ross Island area, northern Antarctic Peninsula. This succession is the most important onshore Late Cretaceous–Tertiary sequence in Antarctica and is probably one of the most significant Cretaceous sequences in the Southern Hemisphere. However, the understanding of the geological and palaeontological evolution of the area has been limited by an incomplete knowledge of the biostratigraphy of this region. Palynological studies are providing a finer resolution biostratigraphical zonation scheme than previously possible. This paper reviews the stratigraphy of the basin fill succession and provides a framework for the papers published in this Special Issue.
Dinoflagellate cysts from an allochthonous block of Nordenskjöld Formation (Upper Jurassic), north-west James Ross Island
Authors: Snape Michael G.
Published: December 2007

An allochthonous block of the Nordenskjöld Formation from north-west James Ross Island, Antarctic Peninsula has yielded a diverse marine palynoflora. Dinoflagellate cyst assemblages from the 185 m thick sequence are described and compared with similar microfloras previously described from Australia, Papua New Guinea and Madagascar. A mid Tithonian (Late Jurassic) age is suggested for the section. One new genus, Helbydinium gen. nov. and four new species, Helbydinium scabratum sp. nov., Leptodinium acneum sp. nov., Leptodinium posterosulcatum sp. nov. and Rhynchodiniopsis foveata sp. nov. are described.
Dinoflagellate cysts from the Rabot Member (Santa Marta Formation) of eastern James Ross Island
Authors: Sumner Paul W.
Published: December 2007

Palynomorph assemblages dominated by dinoflagellate cysts are described from seventeen samples from the Rabot Member of the Santa Marta Formation at Ekelöf Point, eastern James Ross Island, Antarctic Peninsula. Although the assemblages are of relatively low diversity, the dinoflagellate cyst taxa recorded indicate a mid to late Campanian (Late Cretaceous) age. Changes in species diversity, dominance and gonyaulacacean ratio suggest a gradually reducing distance from shore during deposition, with a return to more offshore conditions towards the section top. A new species of dinoflagellate cyst, Isabelidinium papillum, is described.
Palynology of the Marambio Group (Upper Cretaceous) of northern Humps Island
Authors: Dolding Philip J.D.
Published: December 2007

Palynological analyses of the Marambio Group sediments of Humps Island (Santa Marta and López de Bertodano formations) indicates that there is minor displacement across a prominent NW–SE trending normal fault which passes beneath the southern bluff. No major compositional differences were perceived between the palynomorph assemblages either side of the fault. A late Campanian age is suggested for both sequences, based on comparison with Australasian dinoflagellate cyst zonations. A new species of the dinoflagellate cyst Bourkidinium has been recorded from strata on either side of the fault. A significant number of recycled Permian and Early Cretaceous palynomorphs were recorded. Most are miospores and exhibit significant variation in preservational states, implying derivation from several sources. More thermally mature Permian gymnosperm pollen is most likely derived from the nearby Trinity Peninsula Group, exposed on the Antarctic Peninsula. The source of the relatively well preserved Permian pollen is problematic.
Microplankton from the Cape Lamb Member, López de Bertodano Formation (Upper Cretaceous), Cape Lamb, Vega Island
Authors: Smith Sandy W.
Published: December 2007

Samples from the lower Cape Lamb Member, López de Bertodano Formation, Cape Lamb, Vega Island, Antarctic Peninsula have yielded rich and diverse marine palynofloral assemblages. The overall character of the palynofloral assemblages indicate a latest Campanian–earliest Maastrichtian age. Four new dinoflagellate cyst species Canninginopsis ordospinosa sp. nov., Microdinium ? gymnosuturum sp. nov., Phelodinium exilicornutum sp. nov. and Operculodinium radiculatum sp. nov. are described. Certain key dinoflagellate cyst taxa such as Operculodinium radiculatum sp. nov., Manumiella n. sp. 3 and Isabelidinium cretaceum allow a correlation of the lower Cape Lamb Member with the upper palynomorph zone 1/lower zone 2 on nearby Seymour Island.
Eocene microplankton from La Meseta Formation, northern Seymour Island
Authors: Cocozza Christopher D. , Clarke Ciara M.
Published: December 2007

Twenty two samples collected from the Tertiary La Meseta Formation of Cape Wiman, Seymour Island, Antarctic Peninsula yielded abundant and moderately diverse assemblages of marine palynoflora, dominated by dinoflagellate cysts, together with acritarchs and chlorophyta. The assemblages can be divided into three association: Association 1, characterized by low diversity dinoflagellate assemblage of late Early Eocene age which are dominated by Enigmadinium cylindrifloriferum; Association 2 characterized by more diverse dinoflagellate cyst assemblages, which show a marked decrease in the dominance of E. cylindrifloriferum, and an increase in relative abundance of Areosphaeridium cf. diktyoplokus; and Association 3 which is characterized by a decrease in dinoflagellate cyst diversity up section. Changes in dinoflagellate cyst dominance and diversity throughout the section suggests a gradation from a stressed, shallow marine palaeoenvironment to a more open near-shore, shallow marine system becoming progressively more nearshore up section. The assemblages are no older than late Early Eocene in age, and possibly as young as Mid–Late Eocene.
Late Cretaceous palaeoenvironments and biotas: an Antarctic perspective
Authors: Crame J. A.
Published: December 2007

The Cretaceous period is often regarded as one of "greenhouse" warmth, with perhaps its acme occurring in the late Albian stage (100 Ma ago). However, it is now apparent that, even at this time, there were significant meridional temperature gradients and distinct temperate biotas in the highest latitude regions. This is particularly so in the Southern Hemisphere, where an extensive Albian fossil record from Antarctica, Australia and New Zealand has revealed the presence of austral floras and faunas. With the recent improvements in stratigraphical correlations, it has become possible to trace the later Cretaceous palaeoenvironmental record in the Antarctic Peninsula region. Unfortunately, resolution of the early Late Cretaceous (Cenomanian–Coniacian stages) is still imprecise; there are some indications of strongly differentiated palynological assemblages, but studies of both macrofaunas and palaeotemperature estimates are incomplete. By the Santonian–Campanian, high-latitude biotas are well developed in the James Ross Island region and their enhancement through the final stages of the Cretaceous can be linked to a phase of global cooling. The persistence of low diversity temperate communities in high latitude regions may be of considerable ecological and evolutionary significance. For example, there is evidence to suggest that these communities may have been more resistant to mass extinction events; they may also have been important source regions for replacement taxa that arose after such events.
Temperature variation and its biological significance in fellfield habitats on a maritime Antarctic island
Authors: Davey M. C. , Pickup J. , Block W.
Published: December 2007

Temperatures within soil and plant habitats on Signy Island in the maritime Antarctic were measured during 1987. Four sites were monitored using minithermistors attached to a data logging system. Three main periods within the annual temperature cycle were identified. In spring/summer (November–March) there was much inter-day variation in maximum temperatures, but minimum daily temperatures were always close to 0°C. However, there were very few freeze-thaw cycles extending below the −0.5°C threshold during this period, and those that occurred were not severe. It is considered that freeze-thaw cycling is unlikely to be a significant factor in organism survival during summer. All sites showed a long period of relatively mild subzero temperatures during autumn (March–May). This may be of importance in promoting cold-hardiness of organisms living in these ecosystems before the decline to lower winter temperatures. Minimum winter temperatures varied markedly between sites; lowest temperatures occurring in areas where there was little insulating snow cover. Within site temperature variation was generally small, confirming the validity of the use of small numbers of probes to monitor environmental temperatures in such habitats.
Bycatch of fish in the South Atlantic krill fishery
Authors: Everson Inigo , Neyelov Alexei , Permitin Yuri E
Published: December 2007

Icefish (Champsocephalus) were taken as bycatch during krill fishing operations from a research vessel. The data indicate that the bycatch of fish in the commercial krill fishery may be significant in some areas of the South Georgia shelf. The problem is thought to be least in open ocean krill fishing.
Foraging ecology of southern elephant seals in relation to the bathymetry and productivity of the Southern Ocean
Authors: McConnell B. J. , Chambers C. , Fedak M. A.
Published: December 2007

Southern elephant seals (Mirounga leonina) are among the most proficient of mammalian divers and are a major component of the Antarctic food web. Yet little is known of their movements or interaction with their oceanic environment. Specially designed satellite-link data loggers allowed us to visualize the 3-D movements of elephant seals as they swam rapidly from South Georgia to distant (up to 2650 km) areas of Antarctic continental shelf. One seal dived continuously to the sea bed in one small area for a month, implying consumption of benthic prey. Dives here were shorter even though average swimming velocity was lower. It is suggested that the physiological requirements of feeding and digestion reduced the aerobic dive limit. Long distance travel to relocatable hydrographic or topographical features, such as shelf breaks, may allow large predators to locate prey more consistently than from mid-ocean searches.
Loss of soluble carbohydrates and changes in freezing point of Antarctic bryophytes after leaching and repeated freeze-thaw cycles
Authors: Melick D. R. , Seppelt R. D.
Published: December 2007

Healthy samples of Grimmia antarctici (turf and cushion ecodemes), Ceratodon purpureus, Bryum pseudotriquetrum and Cephaloziella exiliflora were collected in late summer in Wilkes Land together with senescing and dead G. antarctici material. Plant material was subjected to leaching in water and up to 16 freeze-thaw cycles. Gas chromatography revealed that following 16 days immersion, loss of carbohydrates (mainly glucose and fructose) was relatively low (c. 10–29% of the total sugar pool) for healthy material, with the loss of 69% from the dead G. antarctici material. Freeze-thaw cycles greatly increased rates of sucrose leakage and led to a 2–3 times rise in total sugar loss in all samples except the dead brown tissue which was not significantly different from the leached control treatment. After 16 freeze-thaw cycles Bryum pseudotriquetrum had lost 65% of total sugar pool. Losses for other species were below 28%. Differential thermal analyses showed freezing points of tissue varied from −8.3 to −3.5°C with dead material having the highest freezing temperatures. There was no significant correlation within species of freezing temperature changes with progressive sugar loss. The results are discussed in relation to nutrient cycling, soil microbial activity and the viability of bryophyte species in the Antarctic environment.
Polyol and sugar content of terrestrial plants from continental Antarctica
Authors: Roser David J. , Melick D.R. , Ling H.U. , Seppelt R.D.
Published: December 2007

Ethanol extractable polyols and sugars from the dominant cryptogams of the Windmill Islands, Wilkes Land, East Antarctica, were characterized and quantified by gas liquid chromatography. Arabitol, ribitol and mannitol were the major low molecular weight carbohydrates extracted from all eight species of lichen analysed. Total extractable carbohydrate levels (20–60 mg g−1 dry weight) were comparable to those for temperate lichens. Extracts of four common bryophyte species were dominated by sucrose, glucose and fructose; little polyhydric alcohol was detected except in the liverwort Cephaloziella exiliflora which contained a substantial proportion of mannitol. Total carbohydrate levels in the bryophytes (9–60 mg g−1 dry weight) were comparable to those in lichens. The compositions of eight species of algae varied considerably. Prasiola crispa, Desmococcus vulgaris and Schizogonium murale possessed sorbitol as their main constituent and had extractable carbohydrate contents comparable to those found in bryophytes on a dry weight or chlorophyll a content basis. The one snow alga with comparable carbohydrate levels, Mesotaenium berggrenii, contained sucrose, glucose, glycerol and a number of unidentified compounds. The remaining four species (Oscillatoria sp., Chloromonas sp.1 and Chlorosarcina sp. 2 and Chlamydomonas pseudopulsatilla) did not accumulate comparable levels of sugars and polyols. Though the levels of these compounds were much lower in the Windmill Islands lichens than in maritime Antarctic species, their content with respect to water content (0.7–7 molal) was well above that at which cold acclimated plants accumulate these compounds (c. 100–500 millimolal), and which provide cryoprotection in vitro. In the case of the bryophytes and algae, however, the in vivo content was generally < 100 millimolal.
Reproduction and larval growth of Harpagifer antarcticus Nybelin (Pisces, Notothenioidei)
Authors: White M. G. , Burren P. J.
Published: December 2007

The spiny plunder-fish, Harpagifer antarcticus, is a common shallow-water demersal species distributed along the southern limb of the Scotia Arc. A year round study was made of its reproductive biology at Signy Island, South Orkney Islands, for comparison with populations from the Antarctic Peninsula and with H. georgianus at South Georgia. Adult H. antarcticus inhabit rubble substrata and spawn 300–1500 eggs into a nest during May/July. The nest is guarded by both male and female fish during an incubation period of up to 150 days. After hatching during November/December the larvae grow at a rate of 0.082 mm d−1 (summer), 0.049 mm d−1 (winter) and 0.067 mm d−1 (annual), calculated from a time-series of samples collected from the field. This rate of growth is slow even among Antarctic species but is similar to the closely related species H. georgianus. Adult male and female H. antarcticus at the South Orkney Islands attain a maximum standard length of 88 mm and 85 mm respectively.
Sedimentary basins on the east flank of the Antarctic Peninsula: proposed nomenclature
Authors: Del Valle R.A. , Elliot D.H. , Macdonald D.I.M.
Published: December 2007

The first fossils from Antarctica were collected from Seymour Island in December 1892, during the voyage of the Jason under Captain C.A. Larsen. The Swedish South Polar Expedition of 1901–1903, led by Otto Nordenskjöld, proved that there were extensive deposits of fossiliferous Cretaceous and Tertiary sedimentary rock in the James Ross Island area. This was confirmed by later geological mapping (Bibby 1966). Subsequent investigations have led to the establishment of various lithostratigraphic schemes (e.g. Ineson et al. 1986), and interpretation of the sedimentary history in terms of basin evolution (Elliot 1988, Macdonald et al. 1988). Unfortunately, different names have been proposed for the depositional basin, with consequent confusion. The purpose of this note is to review previous usage and propose a new consistent nomenclature for the sedimentary basins east of the Antarctic Peninsula.
Antarctic Science—5th BIG year!
Authors: Walton D. W. H. , Thomson M. R. A. , Mobbs S. D.
Published: December 2007

As Antarctic Science enters its fifth year, it is time to assess progress and review the opportunities for Antarctic research in the coming years. The journal appears to have filled a useful niche, established arange of regular (and irregular!) contributors, and is taken by the majority of major polar libraries world-wide. Quality of production has improved with new equipment but rate of publication has fallen with increasing numbers of acceptable contributions. Cross-disciplinary papers have been few — but perhaps that is because few Antarctic scientists have undertaken the challenge of cross-disciplinary studies? Glaciology and most aspects of atmospheric sciences are still under-represented.

Our first special issue on the palynology of James Ross Island has been well received and a second, on a Southern Ocean cephalopod symposium, is planned for 1994. These special issues are a bonus to subcribers who get the extra pages free. The editors are keen to receive proposals for other special issues with offers of appropriate funding.
Diving behaviour of chinstrap penguins at Seal Island
Authors: Bengtson John L. , Croll Donald A. , Goebel Michael E.
Published: December 2007

Diving behaviour of chinstrap penguins (Pygoscelis antarctica) was studied in four adults brooding chicks on Seal Island, South Shetland Islands, Antarctica. During foraging trips to sea, chinstrap penguins made shallow, short duration dives almost continuously, for the most part within 50 m of the surface. Diving effort was concentrated during the daylight hours (10h00-15h00), although a second peak in effort was seen around midnight (22h00-02h00). These peaks were possibly due to the constraints of visual location of prey, chick provisioning, or the need to take advantage of diurnal changes in krill swarm densities or behaviour. It was estimated that most effort was concentrated 3-20 km from shore. Dive depth and duration averaged 31.0 m (± 26.3m) and 72s(± 36s), respectively. Maximum dive depth and duration were 121m and 180s, respectively.
Limnological features of the saline lakes of the Bunger Hills (Wilkes Land, Antarctica)
Authors: Kaup E. , Haendel D. , Vaikmäe R.
Published: December 2007

Twelve saline lakes 5-35m above sea level in Bunger Hills (66°10'S, 101°00'E) were investigated from January to April in 1987-89. Some lakes may be relict and all were subject to wind-borne marine salts with present salinities between 3.4-79.0°/‰ and δ18O values mostly between -10 to -14%. Temperatures up to 17.7°C were measured at the bottom of Lake Polest where a sharp thermohalocline was observed during the period of open water. Mg2+ dominated over Ca2+ in all the lakes. Phosphates concentration was 3-10 μgP I-1 and total phosphorus 8-16 μgP I-1. The concentrations of nitrates and nitrites were often equal, ranging between 1-4 μgN I-1. Dissolved O2 was usually near saturation levels but peaked at more than 230% of saturation in the hypolimnion of Lake Polest as a result of temperature-enhanced photosynthesis with an assimilation rate of 23.9 mgC (mg Chl a)-1h-1. The values for chlorophyll a were 0.26-1.93 mg m-3 and for primary production 0.013-0.171 gCm-3d-1, the latter being an order of magnitude higher than in the fresh water lakes of the Bunger Hills.
Structural characteristics and development of sea ice in the western Ross Sea
Authors: Jeffries M. O. , Weeks W. F.
Published: December 2007

The internal structure of ice cores from western Ross Sea pack ice floes showed considerable diversity. Snow-ice formation made a small, but significant contribution to ice growth. Frazil ice was common and its growth clearly occurred during both the pancake cycle and deformation events. Congelation ice was also common, in both its crystallographically aligned and non-aligned varieties. Platelet ice was found in only one core next to the Drygalski Ice Tongue, an observation adding to the increasing evidence that this unusual ice type occurs primarily in coastal pack ice near ice tongues and ice shelves. The diverse internal structure of the floes indicates that sea ice development in the Ross Sea is as complex as that in the Weddell Sea and more complex than in the Arctic. The mean ice thickness at the ice core sites varied between 0.71 m and 1.52 m. The thinnest ice generally occurred in the outer pack ice zone. Regardless of latitude, the ice thickness data are further evidence that Antarctic sea ice is thinner than Arctic sea ice.
Revised interpretations of Mesozoic palaeogeography and volcanic arc evolution in the northern Antarctic Peninsula region
Authors: Rees P. M.
Published: December 2007

Terrestrial sedimentary rocks at Hope Bay, northern Graham Land are well known for their diverse but poorly-preserved fossil flora, previously assigned ages ranging from Early Jurassic-Early Cretaceous. The beds form part of the Botany Bay Group, which comprises several outcrops of terrestrial sediments in northern Graham Land and the South Orkney Islands. A latest Jurassic or earliest Cretaceous age for the Hope Bay plant bearing sequence (and by extension for the rest of the Botany Bay Group) has been adopted in most recent publications dealing with Mesozoic volcanic arc evolution and palaeogeography of the northern Antarctic Peninsula region. New evidence, based upon the study of extensive collections of previously undescribed fossil plants from Hope Bay and nearby Botany Bay, indicates that they should be assigned an Early Jurassic age. The new palaeobotanical findings, combined with recently-published radiometric data from overlying volcanic sequences, show that a Cretaceous age is no longer tenable for these floras nor, therefore, for the Botany Bay Group in Graham Land. Interpretations of Mesozoic volcanic arc evolution and palaeogeography in this region are revised accordingly.
Geology of the Bunger Hills area, Antarctica: implications for Gondwana correlations
Authors: Sheraton John W. , Tingey Robert J. , Black Lance P. , Oliver Robin L.
Published: December 2007

The Bunger Hills area of the East Antarctic Shield consists of granulite-facies felsic orthogneiss, with subordinate paragneiss and mafic granulite. The igneous precursors of granodioritic orthogneiss were emplaced 1500-1700 Ma ago, and late Archaean (2640 Ma) tonalitic orthogneiss occurs in the nearby Obruchev Hills. Peak metamorphism (M1) (at about 750-800°C and 5-6kb) occurred 1190 ±15 Ma ago (U-Pb zircon age), and was accompanied by the first of three ductile deformations (D1). Emplacement of voluminous, mainly mantle-derived plutonic rocks, ranging from gabbro, through quartz monzogabbro and quartz monzodiorite, to granite, followed between 1170 (during D3) and 1150 Ma. Intrusion of abundant dolerite dykes of four chemically distinct suites at about 1140 Ma was associated with shear zone formation, indicating at least limited uplift; all subsequent deformation was of brittle-ductile type. Alkaline mafic dykes were emplaced 500 Ma ago. Marked geochronological similarities with the Albany Mobile Belt of Western Australia suggest that high-grade metamorphism occurred during collision between the Archaean Yilgarn Craton of Australia and the East Antarctic Shield about 1200 Ma ago.
Investigations of the lower ionosphere over Antarctica via ELF-VLF radiowaves
Authors: Reznikov A. E. , Sukhorukov A. I. , Edemskii D. E. , Kopeikin V. V. , Morozov P. A. , Ryabov B. S. , Shchekotov A. Yu. , Solov'Ev V. V.
Published: December 2007

The paper discusses ELF-VLF investigations of the low Antarctic ionosphere. Two new methods of lower ionospheric diagnostics are based on an investigation of the VLF electromagnetic field structure in the Earth-ionosphere cavity. One method deals with the analysis of local transverse cavity resonances in the near field of an emitter (a horizontal antenna) with a frequency (~1.5-8 kHz) in the range of the first few resonances. The other method, based on tweek investigations, is applicable under night conditions and enables the characteristics of the low ionosphere to be determined over a signal propagation path. The use of the ELF-VLF transmitter at Siple Station provides a unique opportunity to implement these methods, as does the ELF multipoint recording in the Schumann resonance band of atmospherics excited by powerful lightning discharges.
Ethics and animal experiments
Authors: Walton D. W. H.
Published: December 2007

There is great biological interest in the birds and marine mammals of Antarctica. They are numerous, obvious and apparently well adapted to an extreme and highly seasonal environment. What specific ecological and physiological adaptations have made them so successful? In pursuit of the answers to this biologists, over many decades, have undertaken a wide variety of experiments on seals and birds—especially penguins.
Temporal and spatial variations of phytoplankton from Boeckella Lake (Hope Bay, Antarctic Peninsula)
Authors: Izaguirre I. , Mataloni G. , Vinocur A. , Tell G.
Published: December 2007

The main water body at Hope Bay, Boeckella Lake, was sampled at four sites for phytoplankton during summer 1991 to assess the influence of nutrients from nearby penguin rookeries on both phytoplankton density and composition. The site located at the base of the rookeries had total phosphorus values comparable to those reported from the most eutrophic Antarctic lakes. During the ice-free period most of the Chlorophyceae and Cyanophyceae recorded were concentrated at this site. Phytoplankton density increased strongly in the area opposite to the rookeries where ice began to form; an under-ice bloom of Ochromonas aff. ovalis (Chrysophyceae) was observed in this area.
Breeding habitats of emperor penguins in the western Ross Sea
Authors: Kooyman Gerald L.
Published: December 2007

Within the Western Ross Sea, there are six emperor penguin colonies of widely different size that occur exclusively on sea ice. In 1990 a survey of all six sites, two by close overflights and four from the ground, showed that the breeding habitats were highly variable. The most important physical characteristics of these habitats appear to be stable fast ice, nearby open water, access to fresh snow, and shelter from the wind.
Polychaetes of the shallow sublittoral of Admiralty Bay, King George Island, South Shetland Islands
Authors: Sicinski Jacek , Janowska Ewa
Published: December 2007

Twenty five species of Polychaeta were recorded in soft bottom samples collected from 4–30 m. Total abundance of polychaetes ranged from 60 to 3300 m-2. High abundance values were locally recorded for Microspio moorei, Tharyx epitoca and Ophelina syringopyge. These species, together with more regularly distributed Capitella capitata and Scoloplos marginatus, constituted over 70% of all specimens. Total biomass value of the polychaetes varied between 3.8 and 46.4 gm-2. Travisia kerguelenensis and Aglaophamus ornatus constituted over 75% of total biomass. Species composition, richness and diversity of the polychaete assemblage varied with depth. Two parts of the investigated bottom section, differing in the polychaete assemblages structure, were distinguished; the first one in the depth range from 4–20 m and the second one at the depths of 25–30 m. On the basis of both new and previously published data two types of polychaete assemblages of the shallow soft bottom of the Antarctic sublittoral were distinguished. The type of sediment seems to be the main factor influencing the composition of polychaete assemblages.
The lipid composition of Euphausia superba Dana in relation to the nutritional value of Phaeocystis pouchetii (Hariot) Lagerheim
Authors: Virtue P. , Nichols P. D. , Nicol S. , McMinn A. , Sikes E. L.
Published: December 2007

The fatty acid profiles of Euphausia superba, the Antarctic prymnesiophyte, Phaeocystis pouchetii, and a temperate diatom, Phaeodactylum tricornutum were analysed and compared. The lipid content, lipid class, fatty acid and sterol composition of E. superba fed on each cultured phytoplankton and a mixed diet of both species, were determined. No significant difference was found between total lipid levels of E. superba reared on each of these different diets. Phaeocystis pouchetii, although deficient in a number of the essential fatty acids, is apparently an adequate food source for E. superba. The proportion of polyenoic fatty acids varied within lipid classes although there was no significant difference between levels of the long chain polyunsaturate 20:5(n-3) in the total lipid of E. superba fed on these diets. This acid was found to be less than 1% of the total lipid in Phaeocystis pouchetii compared to 37% in Phaeodactylum tricornutum. This suggests that krill may possess the ability to convert exogenous shorter chain fatty acids to 20:5(n-3) and 22:6(n-3). Significant differences were detected in the isomeric ratio of 16:1(n-7c)/16:0 between krill fed the diatom compared to the prymnesiophyte diet. Significant differences were also detected in several shorter chain fatty acids and between fatty acids within their lipid classes. Such differences may have the potential to be used as biochemical signatures to provide information on food sources and possible feeding grounds of E. superba. Phaeocystis pouchetii in a very late stationary phase, although not used in this feeding study, was found to contain 11% of 22:6(n-3) for which there are few substantive sources in natural algal populations.
The deformational history of the Larsemann Hills, Prydz Bay: the importance of the Pan-African (500 Ma) in East Antarctica
Authors: Dirks Paul H. G. M. , Carson Chris J. , Wilson Chris J. L.
Published: December 2007

The Larsemann Hills represent a low-pressure granulite terrain with a complex structural-metamorphic history that comprises two parts: 1) granulite facies D1 structures transposed within an early form surface that probably formed at 1000 Ma, and 2) a sequence of progressive, upper amphibolite to lower granulite facies D2–D6 structures that formed during the Pan-African at 500 Ma and were associated with the emplacement of granites and pegmatites with high-grade alteration zones. D2–D6 events comprise an early form surface that has been tightly folded and sheared twice after which it was warped and transected by discrete mylonites. D2–D6 assemblages are associated with decompression textures on D1 peak-assemblages, such as cordierite coronas on garnet + sillimanite in metapelite and plagioclase coronas on garnet in metabasite. This suggests that D2–D6 formed at slightly lower pressures than D1 structures. However, the spatial correlation between the coronas and alteration zones around pegmatitic intrusives indicates that the apparent decompression textures may have partly resulted from transient fluxes in water pressure following melt crystallization. Throughout East Antarctica tectonic provinces have been recognized in which the 1000 Ma tectonothermal events are identified as the main stage in the evolution, and Pan-African events are dismissed as a minor thermal overprint. Although the Larsemann Hills are small in area, they are representative of a great many granulite terrains in East Antarctica, and suggest that great care is needed in the structural-metamorphic analysis of such terrains to ensure the separation of tectonic stages before an interpretation of the tectonic path is attempted.
Zircon ages and the distribution of Archaean and Proterozoic rocks in the Rauer Islands
Authors: Kinny P. D. , Black L. P. , Sheraton J. W.
Published: December 2007

The application of zircon U-Pb geochronology using the SHRIMP ion microprobe to the Precambrian high-grade metamorphic rocks of the Rauer Islands on the Prydz Bay coast of East Antarctica, has resulted in major revisions to the interpreted geological history. Large tracts of granitic orthogneisses, previously considered to be mostly Proterozoic in age, are shown here to be Archaean, with crystallization ages of 3270 Ma and 2800 Ma. These rocks and associated granulite-facies mafic rocks and paragneisses account for up to 50% of exposures in the Rauer Islands. Unlike the 2500 Ma rocks in the nearby Vestfold Hills which were cratonized soon after formation, the Rauer Islands rocks were reworked at about 1000 Ma under granulite to amphibolite facies conditions, and mixed with newly generated felsic crust. Dating of components of this felsic intrusive suite indicates that this Proterozoic reworking was accomplished in about 30–40 million years. Low-grade retrogression at 500 Ma was accompanied by brittle shearing, pegmatite injection, partial resetting of U-Pb geochronometers and growth of new zircons. Minor underformed lamprophyre dykes intruded Hop and nearby islands later in the Phanerozoic. Thus, the geology of the Rauer Islands reflects reworking and juxtaposition of unrelated rocks in a Proterozoic orogenic belt, and illustrates the important influence of relatively low-grade fluid-rock interaction on zircon U-Pb systematics in high-grade terranes.
A bottom simulating reflector on the South Shetland margin, Antarctic Peninsula
Authors: Lodolo E. , Camerlenghi A. , Brancolini G.
Published: December 2007

Multichannel seismic data acquired over the northern Pacific margin of the Antarctic Peninsula, have shown the presence of high-amplitude sub-bottom reflections across part of the South Shetland accretionary prism. Detailed seismic data analysis, such as true amplitude signal recovery, reflection coefficient determinations and closely-spaced semblance velocity analysis, have been carried out in order definitely to assign this bottom simulating reflector to the base of the stability field for methane hydrate. This represents the first evidence of gas hydrate layers in the Antarctic Peninsula region.
Evidence for an Antarctic winter coastal polynya
Authors: Anderson P. S.
Published: December 2007

Satellite infra-red imagery and meteorological data suggest the presence of winter open water (polynya) in the coastal pack ice to the north and west of the Brunt Ice Shelf. Satellite imagery, although only available for a limited number of occasions, provides evidence for the polynya during the austral winter of 1991. Indirect meteorological observations from the British Antarctic Survey's Halley station (75° 36′S, 26° 42′W) provide very strong supporting evidence of open water to the west of the ice shelf in previous years.
The SCAR Antarctic digital topographic database
Authors: Thomson J. W. , Cooper A. P. R.
Published: December 2007

The Antarctic digital topographic database is the outcome of a truly international collaborative project between 11 nations. Data capture was co-ordinated in the UK, under the auspices of the Scientific Committee on Antarctic Research (SCAR), during a two-year period. Over 200 maps, at scales ranging from 1:200 000 to 1:5 000 000, were digitized for the project and reference was made to a similar number of satellite images (mostly Landsat photographic products). Editing and harmonization of the data derived from the different sources has produced a seamless map of Antarctica which has the most up-to-date coastline now available. The topographic database created, to be published on one CD-ROM, will form the foundation for future GIS needs in Antarctic research. Products already derived from the database include digital elevation models and customized maps; the latter can be reproduced by research groups to meet their own mapping needs.
Fatty acid, sterol and hydrocarbon composition of Antarctic sea ice diatom communities during the spring bloom in McMurdo Sound
Authors: Nichols David S. , Nichols Peter D. , Sullivan Cornelius W.
Published: December 2007

The lipid composition of microalgal communities dominated by diatoms collected from the sea ice at three locations within McMurdo Sound during the austral spring bloom of 1989/90, was determined using gas chromatography (GC) and GC mass spectrometry. A range of C27-C29 sterols were detected. The major sterols found at the three sites were 24-methylcholesta-5, 22E-diene-3β-ol (Cape Armitage); trans-22-dehydrocholesterol, 24-ethylcholesterol and 24-methylenecholesta (Erebus Ice Tongue); and 24-methylenecholesterol (Cape Royds). The difference in sterol profiles is believed to reflect the differing species composition at each site. The high relative levels (as % of total) of 24-ethylcholesterol at the Erebus Ice Tongue site (possibly related to Amphiprora kufferathii) supports the proposal that diatoms are a more probable source of C29 sterols in Antarctic lakes than are other algal groups or cyanobacteria. Changes in sterol composition over the course of the bloom were evident at the Cape Armitage site, particularly within the cellular free-lipid fraction. The major fatty acids identified were 14:0, 16:0, 16:1ω7c, 16:4ω1 and 20:5ω3 (Cape Armitage and Erebus Ice tongue sites); 16:0, 16:1ω7c and 20:5ω3 (Cape Royds site). All sites demonstrated high levels of PUFA (40–50% of total fatty acids), with an average 20:5ω3 level of 21% Erebus Ice Tongue, 20% Cape Royds, and 17% Cape Armitage. Variation was also observed in the percentage of 20:5ω3 for the Cape Armitage community over the sampling period. Levels of 22:6ω3 were between 0.4 and 1% of total fatty acids for the three sites. A C25:2 isoprenoid hydrocarbon was present in samples from all sites, adding further evidence to the proposal that diatoms are probably a source of this and related isoprenoid alkenes in marine and coastal sediments.
Association of dolerite and lamprophyre dykes, Jetty Peninsula (Prince Charles Mountains, East Antarctica)
Authors: Mikhalsky Eugene V. , Sheraton John W.
Published: December 2007

A compositionally varied swarm of mafic dykes in the Jetty Peninsula area was emplaced about 320 Ma ago (K-Ar age). There are three major groups: Group 1 dykes range from transitional-alkaline dolerites to camptonites, Group 2 are trachydolerites, and Group 3 are diorite to quartz diorite porphyries. Group 1 dykes have very similar ratios of most incompatible elements and were derived from the same (or a very similar) enriched lithospheric mantle source region (∈Nd −0.18 to −3.05) with high Nb and Ta (i.e., OIB, ocean island basalt, characteristics). However, the presence of several distinct subgroups with different incompatible element abundances implies significantly different degrees of melting. Group 2 trachy dolerites are much more fractionated (mg 22–36), but were apparently derived from a similar, although somewhat more enriched (∈Nd −2.26 to −4.63) source. Group 3 diorites are compositionally quite distinct and may have been derived by intracrustal melting. Enrichment of the mantle source(s) of Groups 1 and 2 dykes apparently occurred about the same time as high-grade metamorphism in the area, and may have been coeval with crust formation in nearby parts of Gondwana.
Low salinity frazil ice generation at the base of a small Antarctic ice shelf
Authors: Tison J.-L. , Ronveaux D. , Lorrain R. D.
Published: December 2007

Chemical, isotopic and crystallographic characteristics of marine ice formed at the base of the Hells Gate Ice Shelf, Terra Nova Bay, allow a better understanding of the dynamics of marine ice accretion under small ice shelves. The observed properties of the different types of frazil ice found in the area immediately behind the ice shelf front, result from a progressive evolution of the individual frazil ice crystals initially accreted at the base of the ice-shelf. Basal melting caused by the descending plumes of water masses at a temperature above their local freezing point, initiates partial melting of the frazil ice crystals. This dilutes the interstitial water and initiates chemical sorting effects as diffusion proceeds from the normal sea water in the free water column to the diluted interstitial water in the loose frazil layer. Different environmental conditions will result in contrasting properties. Where the subglacial interface is sculptured with domes or inverted channels, it will favour the accumulation of thick units of frazil ice, in a calm environment, that will be further protected from convection mixing over long time periods. This will result in the formation of orbicular frazil showing c-axes at random, strong dilution and important sorting effects. On the contrary, where no channel or dome exist, or where those are already filled with frazil, rectangular or wave-like banded frazil will form with properties showing interfacial streaming effects induced by water currents. Strong c-axes concentration at a single maximum, less dilution and weaker chemical sorting effects are then observed. These findings provide a tentative explanation for the apparent contradiction between the very low salinity levels detected in marine ice at the base of ice shelves and the comparatively minor salinity fluctuations in sea water profiles near ice shelves.
Poles together
Authors: Vincent W. F.
Published: December 2007

In March 1993 the Atmospheric Environment Service's monitoring network across Canada registered ground-level fluxes of solar ultraviolet-B radiation (UVBR) that were the highest on record. This effect was correlated with the spring-time depletion of ozone in the northern upper atmosphere, and AES predicted that the average depletion over Canada could be this severe or worse for the next 15–20 years. These reports heightened awareness amongst the Canadian public as well as the scientific community about the Antarctic ozone hole, and about the most recent UVBR and atmospheric research findings from Antarctica. The causes and biological impacts of high latitude ozone depletion is but one example where information derived from one polar zone is of vital interest to those living in, or otherwise concerned with the other. In this and other research areas the time is appropriate for a bipolar perspective on Antarctica.
The diet of the blue-eyed shag, Phalacrocorax atriceps bransfieldensis feeding in the Bransfield Strait
Authors: Casaux Ricardo J. , Barrera-Oro Esteban R.
Published: December 2007

The diet of the Antarctic blue-eyed shag Phalacrocorax atriceps bransfieldensis was analysed based on the identification of the prey items in 50 regurgitated casts collected at Duthoit Point, Nelson Island, in February 1991. Fish remains occurred in 100% of the casts and represented 68% by number and 90% by weight of the total prey items. From a total of 2112 otoliths found, 1176 fish specimens were identified belonging to four demersalbenthic species: Harpagifer antarcticus, Notothenia neglecta, Nototheniops nudifrons and Trematomus newnesi. Equations to estimate total length and weight from otolith length are provided. H. antarcticus and N. neglecta were the most frequent (92%) and important by weight (66%) respectively. Cephalopod beaks found indicate benthic octopods as the second group in importance after fish. Other invertebrates such as polychaetes, gastropods, bivalves and crustaceans were only occasional. The presence of algae and stones in the casts is attributed to accidental ingestion. Our results are in general agreement with those published for other Antarctic localities which indicate that P. atriceps is a benthic coastal feeder, with fish as its main food.
Distribution, reproduction and population dynamics of the Antarctic gammaridean amphipod Eusirus perdentatus Chevreux, 1912 (Crustacea)
Authors: Klages Michael
Published: December 2007

The geographical distribution and depth zonation of Eusirus perdentatus Chevreux, 1912 in the eastern Weddell Sea and adjacent Lazarev Sea (Antarctica) is described. A total of 963 individuals of this carnivorous predator caught during six successive cruises at 71 stations between 176 and 799 metres water depths were used. Individuals of E. perdentatus have been kept alive for nearly five months in the laboratory. During this period females released 53 juveniles in April. Oocytes and embryos of females have been counted and measured. The duration of embryonic development in E. perdentatus was estimated at c. 12 months, using an empirical relationship based on the mean diameter of 4390 fertilized eggs. There is strong evidence that this species is semelparous with hatching of juveniles at the end of austral summer. Two methods, herein termed as Year Class Model and Moult Class Model, have been applied in order to describe the growth of females by means of cumulative length-frequency data.
Variations in the distribution of chlorophyll a and inorganic nutrients around South Georgia, South Atlantic
Authors: Whitehouse M. J. , Symon C. , Priddle J.
Published: December 2007

Data collected on four large-scale surveys around the subantarctic island of South Georgia provide information on the variability in the distribution of chlorophyll and inorganic nutrients during the austral summer and winter. During three summer surveys, surface water cholorophyll and nutrient concentrations were highly patchy over scales ranging from a few to hundreds of kilometres. The highest measurement of chlorophyll a was 8 mg m−3 and a wide range of nutrient concentrations were found; 5–32 mmol m−3 NO3−N, 1.1–2.2 mmol m−3 PO4−P and 8–60 mmol m−3 Si(OH)4−Si. In winter, chlorophyll and nutrient levels were far more uniform, with chlorophyll concentrations lower and nutrient concentrations generally higher than in summer. The spatial variability in nutrient concentrations was due to a variety of factors acting over a range of scales, however biological processes appeared most important in creating the mesoscale patchiness around the island. Although phytoplankton abundance and nutrient concentrations were not directly correlated, the scales of variability were clearly similar.
Nearshore population characteristics of the circumpolar Antarctic scallop Adamussium colbecki (Smith, 1902) at Terra Nova Bay (Ross Sea)
Authors: Nigro Marco
Published: December 2007

Adamussium colbecki is one of the dominant members of the nearshore benthic community around Antarctica (Nicol 1966, Dell 1974). It has been studied from a systematic and biogeographic point of view since the beginning of this century (Smith 1902, Pelseneer 1903). However, detailed knowledge of its biology and ecology has been only acquired during the last decade (Stockton 1984, Berkman 1990, Berkman et al. 1991, Mauri et al. 1990, Nigro et al. 1992, Nakajima et al. 1982).