There is a pressing need for region-specific information on the response of polar species to contaminants. The Protocol on Environmental Protection to the Antarctic Treaty states “…regular and effective monitoring shall take place to allow assessment of the impacts of ongoing activities, including the verification of predicted impact…”. Although the Treaty only applies to the Antarctic, similar requirements exist for the Arctic; thus, our comments below apply to both polar regions. Without ecotoxicological information all the effort that is directed towards contaminants monitoring is largely meaningless as it does not tell us whether the levels detected pose an environmental risk.

This review seeks to highlight the potential importance of viruses in Antarctic ecosystems and describe the limited scope of Antarctic virus studies to date, including studies of marine, terrestrial and freshwater communities. Although much of the existing work focuses on the microbial community, there are also studies of virus infection in Antarctic animal and plant populations. We describe methodologies available for the study of viral ecology in the field and in calling for a more intensive research effort discuss how microbial ecology might benefit from the study of viruses in Antarctic ecosystems.

We obtained two years (1999–2001) of continuous, high resolution temperature and pressure data at two near-shore shallow water sites in McMurdo Sound, Ross Sea. Contrary to the long-held assumption of constant freezing conditions in the Sound, these records revealed dynamic temperature fluctuations and substantial warming during January to March reaching peak water temperatures of about −0.5°C. They also revealed that excursions above −1.1°C, the equilibrium melting point of ice in Antarctic notothenioid fish, totalled 8–21 days during the summer. Microscopic ice crystals are known to enter these fish but ice growth is arrested by antifreeze proteins. Prior to this study there were no known mechanisms of eliminating accumulated endogenous ice. The warm temperature excursions provide for the first time a possible physical mechanism, passive melting, for ice removal. The continuous records also showed a correlation between tidal pressures and cold temperature episodes, which suggests the influx of cold currents from under the Ross Ice Shelf may provide a mechanism for ice crystal nucleation as the source of the ice in McMurdo Sound fish. The accumulation of anchor ice on one logger caused it to float up which was recorded as a decrease in pressure. This is the first evidence for the time of onset of anchor ice formation in McMurdo Sound.

The brooded embryos and/or juveniles of the sea stars Neosmilaster georgianus (Studer, 1885) and Lysasterias perrieri (Studer, 1885) and the isopod Glyptonotus antarcticus (Eights, 1853) were examined for their acceptability using the sympatric sea star Odontaster validus (Koehler, 1906) as a predator. Organic extracts were prepared from embryos of both sea stars and juveniles of Lyasterias perrieri and Glyptonotus antarcticus and tested in alginate food pellets to confirm whether lack of acceptability was chemically based. We found both intact whole embryos and juveniles of the sea star Neosmilaster georgianus were not acceptable to Odontaster validus. A methanol extract of the embryos was palatable. This could be the result of either the sequestration of deterrent chemicals within embryos or the presence of noxious compounds that were not extractable in methanol. Embryos and juveniles of the sea star Lysasterias perrieri were not acceptable to sea stars. Food pellets containing methanol extracts of unacceptable embryos were deterrent against sea stars, suggesting a chemical defence. Juvenile brooded isopods (Glyptonotus antarcticus) were also found to be unacceptable in sea star feeding bioassays. Significant rejection of alginate pellets containing a lipophilic dichloromethane methanol extract of juveniles indicated that this lack of acceptability was chemically based. Our study provides further support for chemical defences in the offspring of brooding lecithotrophic Antarctic marine invertebrates.

The aim of this study was to evaluate the hypothesis that Deschampsia antarctica Desv., the only grass of the Maritime Antarctic, responds to temperatures higher or lower than its optimum for photosynthesis (13°C), with the accumulation of heat shock proteins. The LT50 was determined in plants acclimated at 4°C (cold-acclimated plants) and in plants grown at 13°C (control plants) by membrane damage and by the activity of respiratory dehydrogenases. The LT50 was 48.3°C in both groups of plants when determined by membrane damage. When the LT50 was determined by the activity of respiratory dehydrogenases, this was, without significant difference, 47.8°C in cold-acclimated plants and 46.5°C in control plants. Western blot analyses were performed to investigate the accumulation of HSP70 at different temperatures. The optimal temperature for HSP70 accumulation was 35°C in cold-acclimated and control plants. Cold-acclimated plants subjected to a thermal stress of 35°C accumulated HSP70 protein more than control plants subjected to 35°C. After eight hours of continuous stress at 35°C, the maximum relative content of HSP70 in cold-acclimated plants was 1.9 fold higher than control plants. The threshold temperature for HSP70 accumulation was lower in cold-acclimated plants than in control plants. It is concluded that D. antarctica is able to tolerate heat stress with an LT50 similar to those of heat tolerant plants and that the cold-acclimated plants accumulate higher levels of HSP70 than those grown at 13°C.

Annual land-fast ice, particularly an unconsolidated layer or “platelet ice-like” layer (PLI), was sampled in spring 1995 to study the spatial and short-term variations of ice-associated diatoms. Under-ice water, a lead and small polynyas were also sampled. Along a 7 km seaward transect a geographical gradient was evident, with some rare diatom species present only in the offshore PLI, whereas others (mainly pennate diatoms) were ubiquitous. The dense microphytic PLI community as well as the phytoplankton was diatom-dominated, but, within these two communities, marked differences appeared. First, the sea-ice communities (PLI and solid bottom ice) were moderately diverse (36 species), mostly composed of pennate diatoms, of which many were chain forming or tube-dwelling. Dominant taxa were Navicula glaciei, Berkeleya adeliensis, Nitzschia stellata, Amphiprora kufferathii and Nitzschia lecointei. Some differences in the distribution of the most dominant species appeared within the bottom ice and the PLI, attesting to differences in the origin or/and growing capability of these diatoms in these two ice compartments. Under-ice water species composition was mixed with sea-ice communities only on the most coastal sites and during ice melt. Maximum cell numbers were mostly noticed in the PLI, reaching up to 1010 cells l−1 and very high Chl a concentrations (exceptionally up to 9.8 mg Chl a l−1 or 1.9 g Chl a m−2, from a 10 to 20 cm thick PLI layer, close to the continent). Secondly, the phytoplankton in the lead and small polynyas had a low diversity, very low standing stocks (on an average 0.69 μg Chl a l−1) and cell densities (2 × 104 cells l−1). Some species from the polynyas were similar to those of the PLI, such as Navicula glaciei, but others were typically planktonic, such as Chaetoceros cf. neglectus. The presence of encysted cells (Chaetoceros and Chrysophytes) was also noticeable in the polynya water. In early spring no seeding process was obvious from the PLI to polynya water. A comparison with similar fast-ice diatom communities in other parts of coastal Antarctica, is presented.

Geochemical and magnetic data from glacigenic sediments can be useful indicators of past environments and climate. In this paper, the results of X-ray fluorescence (XRF) and rock magnetic analyses are presented for samples from the Pagodroma Group, an assemblage of pre-Quaternary glacimarine sediments preserved as remnants along the raised flanks of the Lambert Graben, Prince Charles Mountains, East Antarctica. Samples were obtained from four formations: Mount Johnston, Battye Glacier, Fisher Bench and Bardin Bluffs, which range in age from late Oligocene or early Miocene through to Pliocene or early Pleistocene. Principal component analysis of the XRF data indicates the occurrence of two main element assemblages, which we infer are determined by the presence in the Bardin Bluffs formation of a significant component derived from Permo–Triassic sedimentary rocks of the Amery Group. Calculation of chemical indices of alteration suggests that the values reflect provenance differences rather than the syndepositional weathering environment. Multidomain ferrimagnetic grains mainly dominate the magnetic mineral assemblages of the samples, probably magnetite, with varying concentrations of high coercivity material, probably hematite.

Two groups of geochemical different dykes have been identified in the Grenville-aged basement of Heimefrontfjella. The first group comprises dykes of continental tholeiite composition which probably intruded during the final stage of indentation of the Kaapvaal—Grunehogna Craton into Laurentia. One dyke of this group yielded an U—Pb zircon SHRIMP age of 1033 ± 7 Ma. The second group has an E-type MORB composition and may be related to ocean floor basalts of the Mozambique Ocean between East and West Gondwana. A preliminary U—Pb SHRIMP age of 586 ± 7 Ma for a single zircon crystal was obtained from a dyke of the second group. During the Pan-African orogeny both dyke groups underwent metamorphism and tectonism at different grades: up to amphibolite-facies in the eastern and southern Heimefrontfjella, and at greenschist-facies in the western and northern Heimefrontfjella. The older dykes may be correlated with the Equeefa suite of southern Natal whereas the younger dyke group is not correlatable with any known mafic intrusions or lava flows in adjacent regions.

Large mafic sills in the Ahlmannryggen region of western Dronning Maud Land were intruded into partially lithified sediments of the mid-Proterozoic Ritscherflya Supergroup. Clastic sedimentary dykes intruding the thick mafic sills have been identified, and show evidence for fluidization of the partially lithified sediments. Previous work had demonstrated in situ fluidization and localized anatectic melting. This study demonstrates mobilization of the fluidized sediments, with penetration at least 50 m into the fractured, intruding sill. Physical features within the clastic dykes (e.g. sediment balls, flame structures) suggest that the sediments were largely unconsolidated, or at most only partially lithified. The presence of a thin zone of anatectic melt along the dyke—sill contact suggests that the mafic sill was still hot (c. 700°C) at the time of sedimentary dyke injection.

A mesoscale experiment was conducted in the Ross Sea near the shelf break in summer 1997–98 within the framework of the activities of the CLIMA Project of the Italian National Program for Antarctic Research (PNRA), focus on study the shelf—slope interaction between the shelf waters and the CDW in correspondence of the Antarctic Slope Front. This paper deals with the dissolved oxygen distribution and with the application of conservative tracers NO and PO related to the physical variables, improving understanding of mixing processes study in correspondence of the shelf break. Experimental data showed the presence of both Ice Shelf Water overflowing the shelf and Circumpolar Deep Water intruding onto the shelf. Dissolved Oxygen (DO), NO and PO resulted useful as chemical tracers in outlining the mixing processes and bottom water formation spreading off continental shelf break of the Ross Sea, in which seems to be evidence that ISW plays an important role. In fact, a plume of ISW was observed flowing down the continental slope to the deep ocean. From chemical tracers we estimate its magnitude to be about 0.4 ± 0.2 Sv.

During the 1997–98 Italian Expedition to Antarctica a five-day mesoscale experiment was carried out on the continental shelf-break in the central Ross Sea. This area is oceanographically characterized by shelf/slope interactions, through intense mixing processes, between the Circumpolar Deep Water (CDW) and the Ice Shelf Water (ISW), coming from beneath the Ross Ice Shelf and spilling over the shelf edge. The export of dense shelf waters is of crucial importance not only for the mass balance of the basin, but also for carbon export from the upper layers into the abyssal ones. The study investigated how the ISW interactions with the CDW may influence bacterial metabolism during an ISW downslope event. In particular, what effect does this have on the bacterial activities related to the utilization and transformation of the organic carbon substrate (ectoenzymatic activities, carbon production, growth rate) within the ISW and the CDW cores? Our data show that in the CDW the metabolic response was to increase the biomass and enzymes were less active due to a higher nutritional value for the substrate. In the ISW the bacterial metabolic activity shifted towards degradative processes. These results suggest differences in the quality of the organic carbon pool with a greater concentration of labile organic matter in the CDW and of low-degradable compounds in the ISW. The use of microbial parameters seems to be very promising in the evaluation of the carbon export during mixing processes, when the refractory fraction of the organic carbon pool might play a key role.