Chemically defended benthic macroalgae that dominate shallow, hard bottom communities along the western Antarctic Peninsula support very high densities of mesograzers, particularly amphipods but also small gastropods. Previous studies have demonstrated that the macroalgae and amphipods form a mutualistic relationship. The chemically defended macroalgae provide the amphipods with a refuge from predation while the macroalgae benefit from the amphipods greatly reducing surface fouling by smaller algae. One of the three most important macroalgae in terms of overstory cover, Himantothallus grandifolius, forms huge blades that can carpet the benthos. Field observations suggest that gastropods may be higher in relative abundance in proportion to amphipods on H. grandifolius than on other overstory macroalgae. The present study documents the finding that natural abundances of gastropods on H. grandifolius maintained in mesocosms reduce fouling by microscopic algae, primarily diatoms. However, amphipods are probably also important in keeping the macroalga clean of diatoms in nature. In a smaller scale experiment, three gastropod species were differentially effective at reducing diatom coverage on H. grandifolius. The hypothesis that gastropods benefit from associating with H. grandifolius in potentially gaining a refuge from sea-star predation was also tested but not supported by the experimental results.

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).

Species inventories are essential to the implementation of conservation policies to mitigate biodiversity loss and maintain ecosystem services and their value to the society. This is particularly topical with respect to climate change and direct anthropogenic effects on Antarctic biodiversity, with the identification of the most at-risk taxa and geographical areas becoming a priority. Identification tools are often neglected and considered helpful only for taxonomists. However, the development of new online information technologies and computer-aided identification tools provides an opportunity to promote them to a wider audience, especially considering the emerging generation of scientists who apply an integrative approach to taxonomy. This paper aims to clarify essential concepts and provide convenient and accessible tools, tips and suggested systems to use and develop knowledge bases (KBs). The software Xper3 was selected as an example of a user-friendly KB management system to give a general overview of existing tools and functionalities through two applications: the ‘Antarctic Echinoids’ and ‘Odontasteridae Southern Ocean (Asteroids)’ KBs. We highlight the advantages provided by KBs over more classical tools, and future potential uses are highlighted, including the production of field guides to aid in the compilation of species inventories for biodiversity conservation purposes.

Previous work focused on allozymes and mitochondrial haplotypes has detected high levels of genetic variability between Cryptopygus terranovus populations, a springtail species endemic to Antarctica, until recently named Gressittacantha terranova. This study expands these biogeographical surveys using additional analytical techniques, providing a denser haplotype dataset and a wider sampling of localities. Specimens were collected from 11 sites across Victoria Land and sequenced for the cytochrome c oxidase subunit I mitochondrial gene (cox1). Haplotypes were used for population genetics, demographic, molecular clock and Bayesian phylogenetic analyses. Landscape distribution and clustering of haplotypes were also examined for the first time in this species. Only three (out of 67) haplotypes are shared among populations, suggesting high genetic structure and limited gene flow between sites. As in previous studies, the population of Apostrophe Island has a closer genetic similarity with those of the central sites, rather than with its neighbours. Molecular clock estimates point to early differentiation of haplotypes in the late/mid-Miocene, also supporting the view that C. terranovus is a relict species that survived on the Antarctic continent during the Last Glacial Maximum. The present genetic composition of populations represents a mixture of ancient and more recent haplotypes, sometimes occurring in the same localities.

This study describes the ecology and distribution of the only two native Antarctic insects, the chironomid species Parochlus steinenii and Belgica antarctica, both found on Byers Peninsula (Livingston Island, South Shetland Islands). Parochlus steinenii inhabits lakes of the central plateau of Byers Peninsula associated with aquatic mosses on the bottom of lakes and in some streams of the South Beach area. Some streams have stable populations which are able to complete their life cycle while other streams have temporary, unstable populations. Belgica antarctica also inhabits streams running through mosses located in the South Beach area. Our data indicate that this species has a limited dispersal capability which is positively light activated for both adults and pupae. Both Antarctic midge species coexists on Byers Peninsula and share some stretches of streams. Isotopic studies show a non-selective feeding regime for both species with mixed carbon sources associated with both biofilm/microbial mats and mosses.

We describe a new association for Antarctica, involving an holothuroid host, Bathyplotes bongraini Vaney, 1914, and a parasitic polynoid polychaete, Eunoe opalina McIntosh, 1885, which lives on the host body. Both species have never been recorded in the study area, the Ross Sea. The ecological definition of this partnership is difficult to assess, being a mix of phoresis, protective association, parasitism and, possibly, kleptocommensalism. Eunoe opalina emerges also as a true predator, ingesting several food items that do not belong to the diet of Bathyplotes. We compare this association with analogous examples known from shallow tropical environments as well as bathyal and abyssal depths. Given the conspicuous similarities between the deep water and high latitude examples of this kind of association, a possible common origin is hypothesized. Although the role of such a kind of parasitic relationships in Antarctic communities remains to be fully evaluated, it seems evident that, at high latitudes, where trophic levels are simplified and food webs do not have much redundancy, the impact of such a ‘multitasking’ predator-parasite as E. opalina might be of a greater magnitude than its shallow water tropical counterpart.

Scales and whole otoliths were used for age estimation of juvenile Notothenia rossii specimens collected at Potter Cove, King George Island, South Shetland Islands, between 1983 and 1988. Results from the analysis of both types of material showed 96.7% agreement. Likewise, the examination of otolith cross sections of chosen specimens confirmed in all the cases the age readings obtained from the second whole sagittal otolith. Although the commonly accepted 1 July was used as the birth date of the fish for age calculations, data indicate that 1 October is closer to the biological birth date, since this species hatches in Spring. The length-age range of the fish was 18–44 cm and 3–7 years respectively, which fits well with the known length-age distribution of juvenile specimens of the species in the fjord. A comparison between observed and back-calculated mean length of age group 3 (24.6 and 25 cm respectively) indicated that not only the larger fish but the full size range of this age group was represented in our samples. Mean length data at age presented here are similar to the ones reported for fish from Admiralty Bay, King George Island, but differ from those of fish caught off Elephant Island. The use of whole otoliths for age estimation of juvenile N. rossii proved to be a reliable method with a precision of one year but, this might not be an appropriate technique for adult specimens.

A detailed profile of the ice fabric, the deuterium content and the sodium concentration of a 1.64 m long, first-year sea-ice core from Breid Bay, near Syowa station (Antarctica), is described. The core consists mainly of frazil ice (77%), a common feature observed in recent extended studies of the first-year sea-ice cover in the Weddell Sea area. Neither snow ice, nor platelet ice is present. The remainder of the core consists of congelation ice. The typical substructure of ice plates/brine lamellae occurs only at the bottom of the core. Otherwise fine-grained congelation ice is ‘sandwiched’ between layers of frazil. It lacks the intracrystalline substructure but shows a strong textural elongation and c-axis clustering in the horizontal plane. The evolution processes of the first-year sea-ice cover in Breid Bay are analysed. The dynamical component, demonstrated to play a major role in the eastern Weddell Sea, seems to be of minor importance in this area, where thermodynamics satisfactorily explains the isotopic, chemical and textural characteristics of the core. It is proposed that the topmost part of the core consists of frazil ice produced by wind- and wave-induced turbulence. Once a consolidated ice cover is provided, the growth proceeds at a slower rate, through congelation ice formation and frazil ice production, initiated by thermohaline convection processes in the water column. The lower alternate layers of fine grained congelation ice and frazil ice could result from cyclic thermal and salinity regimes at the ice-water interface, connected with the major meteorological events of the year.

The formation of a pronival (protalus) rampart on sub-Antarctic Marion Island is investigated. Morphological attributes show debris at the angle of repose on the rampart's proximal slope and at a lower angle on the distal slope. Relative-age dating, based on the percentage moss cover and weathering rind thickness of the clastic component, indicates accumulation mainly on the proximal slope and rampart crest, implying upslope (retrogressive) accumulation. This contrasts with a previously published model for pronival ramparts, which proposes rampart growth by addition of material to the distal slope. Development of the Marion Island rampart is suggested to result from the control exerted by a relatively low-angled surface and a shrinking snowbed. A small debris step formed on the proximal slope appears to be a response to decreased snowfalls due to changing climate over the last c. 50 years. Growth rate of the rampart is considered to be variable during the Holocene in response to changes in climate and debris supply.

Satellite imagery, synoptic-scale analyses and automatic weather station data were used to study a subsynoptic-scale cyclone that developed over the Ross Sea and Ross Ice Shelf areas of Antarctica. A pre-existing subsynoptic-scale midtropospheric cyclone descended from southern Victoria Land into the semi-permanent baroclinic environment over the south-western corner of the Ross Sea. The subsynoptic-scale cyclone then developed into a frontal system travelling south-eastward over the Ross Ice Shelf and decayed five days later over Marie Byrd Land. It is concluded that stretching of the subsynoptic-scale low, while descending over 2000 m from the high plateau down to sea level, increased its cyclonic vorticity via conservation of potential vorticity. This, along with a cold katabatic outbreak into the northern part of the circulation, provided the mechanisms for its initial development. Subsequently, cold boundary-layer air over the Ross Ice Shelf spiralled into the subsynoptic-scale cyclone supporting its further development. An upper-level synoptic-scale cyclone that approached the area provided the upper-level support for its ESE displacement and development.

Lake Vanda, a perennially ice-covered Antarctic lake has a highly stratified structure with a pronounced density gradient from 45 m and is anoxic from 68 m down. In order to gain a greater understanding of the carbon cycling in the lake we attempted to measure sulphate reduction in the summer of 1994, but rates were below detectable limits of 1.2 × 106 mol sulphate yr−1. Therefore sulphate reduction was estimated by calculating the rate of sulphide diffusion from the anoxic zone. Sulphate reduction rates were estimated to be 17.7 × 103 mol sulphate yr−1, accounting for 30% of planktonic primary production over the whole lake, but over 100% of primary productivity in the deep chlorophyll maximum. Radiocarbon dating of organic matter in the sediment (565 ± 50 yr bp), suggests that little new organic carbon reaches the sediment from the upper water column. Oxygen diffusion into the anoxic zone could account for only 44% of sulphide reoxidation; therefore, alternative oxidizing potential presumably accounted for the remainder. Sulphate concentration may be controlled by the solubility limit for a mineral phase, perhaps gypsum, as it shows a positive correlation with conductivity. The sulphur species in the anoxic zone are highly enriched in 34S (sulphate δ34S = + 42 to + 46%0, sulphide δ34S = + 13.9%0) which may be explained by either selective removal of sulphide at the oxic/anoxic interface by precipitation of metal sulphides or previous loss ofH2S to the atmosphere. While sulphate reduction is an important part of the carbon cycle within the lake, the oligotrophic nature of Lake Vanda means that all microbiological process rates are very low. The data presented suggest a dynamic and complex history for Lake Vanda and are entirely consistent with present theories of the lake's history.

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).

Marambionella andreae gen. et sp. nov. from the La Meseta Formation (Upper Eocene–?Lower Oligocene) on Seymour Island is the first fossil clupeid found in Antarctica and the first articulated teleost from the Antarctic Paleogene. It shows a mosaic of similarities and differences compared with various clupeid genera. This and the uncertainty about the polarity of characters within clupeids do not allow precise assessment of the phylogenetic relationships of Marambionella.

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

The Antarctic Pearlwort, Colobanthus quitensis (Kunth.) Bartl. (Caryophyllaceae) is one of the two native vascular plant species that have successfully colonized the maritime Antarctic during the Holocene (Smith 1984). Within the Antarctic biome, it is only found on the Antarctic Peninsula and on islands in the maritime Antarctic (Smith 1984). Its distribution also includes South Georgia (sub-Antarctic), the Falkland Islands, and sites along the Andes, reaching c. 10°N in Mexico (Moore 1970). Moore (1970) observed that C. quitensis is self-compatible and appears to be largely, if not entirely, self-pollinated. Convey (1996), found that maritime Antarctic C. quitensis showed lower allocation to seed production than plants from sub-Antarctic sites.

Cape Dubouzet is mainly composed of a volcanic-subvolcanic complex of extrusive rhyolitic breccias, a banded rhyolite and a semi-annular body of dacite porphyry rich in xenoliths of metamorphic rocks. Major and REE geochemistry indicate that the volcanic rocks are calc-alkaline and that they are genetically related by fractional crystallization of a plagioclase-bearing assemblage from a common magma. Rb-Sr data suggest that the rhyolitic complex is of Middle-to-Late Jurassic age, and that it is intruded by Late Cretaceous stocks of banded diorite and gabbro. All these rocks are partially covered by moraines whose clasts are of local provenance. Xenoliths in the dacite porphyry suggest that the northern tip of the Antarctic Peninsula is underlain by a metamorphic complex composed of amphibolites, meta-tonalites and pelitic gneiss containing garnet, sillimanite, cordierite, hercynite, and andalucite. Such rocks are not known in the Scotia metamorphic complex, nor in the Trinity Peninsula Group and its low grade metamorphic derivatives, which also occur as rare xenoliths in the dacite. Previous dating of xenoliths collected from the moraines suggested a late Carboniferous age for this amphibolite-grade metamorphism. Both the Jurassic-Cenozoic magmatic arc of the Antarctic Peninsula and the accretionary complex rocks of the Trinity Peninsula Group were thus developed, at least in part, over pre-existing continental crust.

A suite of 21 elements, namely Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, La, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V and Zn, was investigated in a sediment core from the Ross Sea, Antarctica. The experimental results were treated by chemometric techniques. The elemental composition of core H2 was found to be mainly dominated by terrigenous elements, but it is also influenced by biological factors, such as the presence of corals. No evidence of anthropogenic contamination was observed, even in the top layer of the sediment. Furthermore, the modified Community Bureau of Reference (BCR) three-step sequential extraction procedure was applied to evaluate metal mobility and availability. The results confirmed the separation between higher and lower sections of the core and showed the presence of Fe as amorphous and crystalline oxide and of Mn mostly as nodules. The high percentages of metals extracted into the fourth fraction indicate their strong binding with the sediment matrix. Finally, BCR procedure was compared to Tessier's protocol which made it possible to distinguish between mobile and mobilizable fraction. Therefore, in general partitioning procedure must be chosen taking into account the nature of the sample and the aim of the research.

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.