A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea region during the winter of 2016 to document the timing and location of spawning activity, to collect biological information about reproductive status during the spawning season and to look for temporal signals in biological data from D. mawsoni that may indicate a spawning migration of mature toothfish from the continental slope region to the northern Ross Sea region. The 58 day survey showed that spawning of D. mawsoni began on some seamounts by early July. No changes were detected between winter and summer in length, age, sex ratio or condition factor distributions for D. mawsoni in the northern Ross Sea as hypothesized following a spawning migration from the slope to the northern Ross Sea region. These results suggest that the distribution of D. mawsoni in the Ross Sea is mainly accomplished through ontogenetic migration and not annual return spawning migrations.

Ixodes uriae White is the only tick species found in Antarctica, and in our research area at Palmer Station it feeds predominantly on Adélie penguins. At the beginning of the summer the ticks leave their off-host aggregation sites, feed on penguins, then subsequently return to their off-host habitats, where they remain until the next summer (Benoit et al. 2007). These ticks have been implicated as a competent vector for Borrelia spirochetes (Olsen et al. 1993) and tick-borne viruses (Nuttall 1984), and are thought to impact development, cause anaemia, alter the thermoregulation, and even lead to the death of penguins (Gauthier-Clerc et al. 1998, Mangin et al. 2003). In this report, we note a striking increase in the number of fed ticks found near Adélie penguin rookeries in 2007 compared to 2006, suggesting that the longer and warmer summer of 2007 may have permitted more ticks to find their hosts. High levels of parasitism could be detrimental to the already declining Adélie penguin populations near Palmer Station (Fraser & Patterson 1997).

The relationship between colony area and population density of Adélie penguins Pygoscelis adeliae was examined to determine whether colony area, measured from aerial or satellite imagery, could be used to estimate population density, and hence detect changes in populations over time. Using maps drawn from vertical aerial photographs of Adélie penguin colonies in the Mawson region, pair density ranged between 0.1 and 3.1 pairs m−2, with a mean of 0.63 ± 0.3 pairs m−2. Colony area explained 96.4% of the variance in colony populations (range 90.4–99.6%) for 979 colonies at Mawson. Mean densities were not significantly different among the 19 islands in the region, but significant differences in mean pair density were observed among colonies in Mawson, Whitney Point (Casey, East Antarctica) and Cape Crozier (Ross Sea) populations. The relationship between colony area and population may be locality-and/or species-specific, and a robust data set is required to validate the relationship.

We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.

Meroplankton community studies in the Antarctic have primarily focused on the coastal waters of both the Antarctic Peninsula and the Ross Sea. The New Zealand International Polar Year - Census of Antarctic Marine Life (IPY-CAML) voyage to the Ross Sea during the late summer (February–March) 2008 provided the first meroplankton samples from three regions in the deep, oceanic waters of the Ross Sea (shelf, slope and adjacent offshore Antarctic waters of Admiralty Seamount and Scott Island). We used a combined morphological and molecular approach to identify 36 larval operational taxonomic units based on sequences from three loci (16S, 18S, COI), and exclude early developmental stages of holoplankton. Overall, larval abundance was lower than previous Antarctic studies (5.19 specimens per 100 m3), with larvae most abundant in the first 200 m of the water column and most diverse in the shelf region. Multivariate analysis revealed significant differences in the meroplankton community between regions and depth ranges, but with low similarity within these groupings; differences between water masses were undetectable due to the confounding effect with both region and depth. The influence of nearby benthic populations (e.g. the acorn barnacle Bathylasma corolliforme) and/or locally abundant taxa (e.g. the nudibranch Tergipes antarcticus) was evident in the meroplankton community.

The McMurdo Dry Valley lakes of Antarctica constitute some of the harshest and most isolated freshwater environments on Earth which might be expected to limit the biogeographical expansion of many organisms. Despite this, we found that the biodiversity of rotifer zooplankton is the highest ever recorded on the Antarctic mainland. We identified in total nine rotifer taxa, of which six are new to the Antarctic continent, in Lake Hoare, and also the first sub-adult crustacean copepod belonging to the genus Boeckella. A possible explanation for the high biodiversity is that many of the recorded species have arrived in the region in relatively recent times and then established invasive populations, suggesting that their distribution pattern was previously limited only by biogeographical borders. Interestingly, we show that the cosmopolitan rotifer taxa identified are relatively abundant, suggesting that they have established viable populations. Hence, our study suggests that the biogeographical maps have to be redrawn for several species.

The flux of gases between the atmosphere and the oceans can be calculated from the product of the concentration difference across the sea surface and a kinetic term, often called a transfer velocity. The transfer velocity is frequently parameterized in terms of wind speed, although the actual exchange process is also affected by waves, bubbles, wind fetch, and less certainly by surfactants and chemical reactivity. There is currently an uncertainty of about a factor of two in using the wind speed parameterization. In view of the windiness of the Southern Ocean, transfer velocities will often be high, although there are few published in situ measurements of transfer rates made in the region. Data for gas concentration fields in the Southern Ocean are generally sparse compared to other better studied oceanic areas. In this paper we discuss what is known for the region for carbon dioxide, including the oceanic sink for man-made inputs to the atmosphere; dimethyl sulphide, where there appears to be a substantial source, which has the potential for a significant climatic effect due to the low particulate loading in the region; and organo-halogen and alkyl nitrate gases, where marine emissions may play an important role in controlling the oxidation capacity of the Antarctic atmosphere.

A four-year set of vertical profiles of pressure, temperature and relative humidity derived from 1113 radiosoundings performed at Dome C (Antarctica) at 12h00 UT of each day, from late March 2005 to the end of March 2009, was examined by following a complex procedure for removing the most important lag errors and dry biases from the temperature and moisture data. The analysis provides evidence of annual cycles over the four years, characterizing the pressure and temperature conditions at the surface and at the various troposphere and low stratosphere levels, with maxima in summer and wide minima in winter for both parameters. Specific studies of the thermal parameters characterizing the ground layer and the tropopause region are also presented to describe their annual average variations. The analysis of moisture parameters indicates that absolute humidity varies regularly with season within the low troposphere, presenting well marked peaks in the summer months. Consequently, precipitable water was found to vary regularly during the year, from values of 0.2–0.4 mm in the winter to more than 0.6 mm in summer. The main year-to-year variations characterizing the monthly mean vertical profiles of pressure, temperature and moisture parameters are also described.

The biogeography of the South Indian Ocean Province (SIP) biotas has long been controversial. Much of the discussion has been based on interpretation of species distributions, based on morphological or anatomical delimitations. However, molecular phylogenetic approaches elsewhere have recently shown that interpretations based solely on morphological data may be misleading. Nonetheless, few studies have employed molecular phylogenetic approaches to understand the biogeography of the SIP biotas. We do so here for the Ectemnorhinus group of genera, a monophyletic unit of weevils endemic to the region. We use mitochondrial cytochrome oxidase I DNA sequence data to reconstruct relationships among 13 species and 22 populations in the genera Palirhoeus, Bothrometopus and Ectemnorhinus. On the basis of this analysis we find little support for separating the genus Palirhoeus from Bothrometopus, and little support for the morphologically-based species groups currently recognized within Bothrometopus. Using a molecular clock we show that dispersal among islands probably took place against the prevailing wind direction. These data also support a previous hypothesis of radiation of the epilithic genera Bothrometopus and Palirhoeus during the Pliocene/early Pleistocene, but reject the hypothesis that the genus Ectemnorhinus radiated following the last glacial maximum. We show that Bothrometopus parvulus (C.O. Waterhouse) on the Prince Edward Islands comprises two species that are not sister taxa. We name the second species Bothrometopus huntleyi n. sp. and provide a description thereof.

Soil preservation from three glacial thermal regimes was examined in the Transantarctic Mountains (TAM) using the University of Wisconsin Antarctic Soils Database (http://nsidc.org/data/ggd221). Glacial thermal regimes included temperate (wet-based) glaciers from overriding of the TAM prior to c. 15Ma bp and subsequent polar (dry-based) glaciers. The glacial thermal regimes were distinguished from landform, sediment and erosional features. Buried soils were most common from deposition by dry-based glaciers (44 of 51 pedons). Several of these buried soils had a desert pavement intact with in situ ventifacts. Fifteen percent of the pedons contained recycled ventifacts in relict and buried soils that ranged from late Quaternary to Miocene in age, particularly in drift from dry-based glaciers (56 of 77 pedons). Overall 84% of the buried soils and 78% of the pedons with recycled ventifacts originated from dry-based glaciers. The proportion of soils with recycled clasts on a particular drift was greatest where the ratio of drift thickness to soil thickness (“recycling ratio”) was the least. These data illustrate the effectiveness of Antarctic dry-based glaciers in preserving underlying landforms and deposits, including soils. Moreover, the data imply that Antarctic glaciers have been recycling clasts for the past c. 15Ma. These findings have important implications in selecting surface boulders for cosmogenic dating.

Bioaugmentation is a controversial strategy. In this work, the effect of the inoculum size and the absence of natural microflora on the efficiency of hydrocarbon removal were studied. Two levels of inoculum (106 and 109 CFU g-1) were applied to soil microcosms containing sterile (S6 and S9) and non-sterile (NS6 and NS9) oil contaminated Antarctic soil. Community controls (CC) and biostimulated autochthonous microflora (BAM) were also included. Total heterotrophic aerobic (THAB) and hydrocarbon degrading (HDB) bacteria as well as total petroleum hydrocarbons (TPH) were analysed. At day 0, THAB and HDB counts (CFU g-1) showed no differences among CC, BAM and NS6 but significantly higher values were observed in NS9 and S9. At day 60, three different levels of HDB were observed. The lower level was represented by CC (106 CFU g-1), a second group (5 x 107 CFU g-1) was represented by BAM, NS6, NS9 and S6, and the third level was constituted by S9 (1 x 109 CFU g-1). TPH values at day 60 decreased significantly in all systems excluding the controls. NS6, NS9, S6 and S9 were not different from those corresponding to BAM. Results suggest that the bioaugmentation of a chronically diesel fuel-contaminated Antarctic soil is unlikely to be profitable or beneficial.

Capture by water surfaces is a frequent but stochastic phenomenon for Antarctic collembolans (springtails), with implications for both the survival and dispersal of populations. This paper provides the first field description of the characteristics of rafting aggregations of the springtail Gomphiocephalus hodgsoni and provides the first observation of the inclusion of the mite, Stereotydeus mollis, within these aggregations. Field observations of aggregations in meltwater pools are used to develop a picture of the ecological implications of rafting for Antarctic springtails. The potential for marine capture was also demonstrated by additional observations of two springtails aerially deposited on to sea ice as well as springtails floating in the tidewater cracks between the sea ice and land.

A nearly complete lower pharyngeal tooth-plate from a large (over 60 cm long) fossil wrasse (Perciformes: Labridae) was recently recovered from the middle to late Eocene La Meseta Formation on Seymour Island, Antarctic Peninsula. This find increases the number of teleosts from the Eocene of Antarctica to five taxa, and further illustrates the diversity of the ichthyofauna in the Eocene Weddellian Sea prior to wide-scale climatic change in the Southern Ocean. The fossil wrasse represents the first occurrence of this family in Antarctica, and is one of the oldest fossils of this family from the Southern Hemisphere. Wrasses are not found in Antarctic waters today, and probably became extinct during the Oligocene due to a combination of climatic change, loss of shallow-water habitat, and changes in the trophic structure of the Wedell Sea.

The diet of the emperor penguin Aptenodytes forsteri (Gray) in Amanda Bay, Princess Elizabeth Land, Antarctica, was studied by analysis of adult stomach contents during part of the chick-rearing period from August to October 1986. The penguins consumed almost entirely fish, mainly Pleuragramma antarcticum (Boulenger) (78% by number and 78% by mass). Other fish species, cephalopods and crustaceans were minor components. These results and those of the only other two, geographically distinct, quantitative studies of the diet of emperor penguins suggest that the diet of this species varies through the effects of local topography and hydrology on prey availability.

Deschampsia antarctica is a freezing-tolerant plant and the only native Poaceae that grows in the Maritime Antarctic. During the long days of the growing season this plant accumulates sucrose (Suc) in the leaves to 36% of the dry weight. The mechanism that leads to this high accumulation is unknown. The effect of day length and low temperature on sucrose phosphate synthase (SPS) (EC: 2.4.1.14) activity and sugar accumulation was studied in D. antarctica and compared with other Poaceae. Three different day lengths: short (SD) (8/16 h), medium (MD) (16/8 h) and long (LD) (21/3 h); and two temperatures: 4°C (cold-acclimated) and 15°C (non-acclimated) were tested. The highest contents in total soluble sugars (TSS) and Suc were reached in crowns and leaves, respectively, in cold-acclimated plants under LD. TSS and Suc contents and SPS activity with cold acclimation were higher in D. antarctica than in other agricultural (wheat, oat and barley) and non-agricultural (D. caespitosa and D. beringensis) Poaceae species. Suc/TSS ratio was higher in all Deschampsia species than in agricultural Poaceae species. SPS activity and sucrose content in leaves were positively correlated only in LD cold acclimated plants. This result shows that SPS activity is responsive to day length in D. antarctica.

The relatively small numbers of pelagic cephalopods caught in the RMT-8 samples (0–300 m) in February/March 1983 in the Weddell Sea were dominated by early life stages of the cranchiid squid Galiteuthis glacialis. A total of 48 specimens were caught with dorsal mantle length (ML) ranging from 4–36 mm. They occurred with a mean density of 0.15 ind. × 1000 m−3 and were present in 38% of 33 RMT-8 samples. G. glacialis was the only cranchiid squid found in the Weddell Sea between 66° and 74°S. Its early life stages were concentrated in the layers below the summer thermocline (>50 m) and body sizes appeared to increase towards deeper water layers. For biochemical analyses, nine specimens of G. glacialis (ML 6–18 mm) were sampled in the eastern Weddell Sea between 185–520 m water depth in January/February 1985. Total lipid contents ranged from 8%–11% dry weight (DW) with phospholipids being the main lipid component (43–56% of total lipid). Storage lipids (triacylglycerols) made up 18–26% of total lipid. The relatively low lipid contents may reflect the early development stage of the specimens examined. The data presented give the first information on geographical and vertical distribution patterns of early life stages of G. glacialis in the high-Antarctic Weddell Sea, as well as on their lipid content and composition.

Antarctica is considered the most isolated continent, but it is not free of pollution, which arrives at specific localities mainly as a result of tourism and research activities. Among environmentally harmful substances, heavy metals are especially important because of their high toxicity to organisms. The aim of this study was to estimate the maximum adsorption of lead (Pb) onto the clay fraction of samples from two soil profiles from the Fildes Peninsula, King George Island, South Shetland Islands. Experimental data were fitted to the Langmuir isotherm, and the adsorption parameters were correlated to mineralogical attributes of this soil fraction characterized by chemical extractions and X-ray diffraction. Values of maximum adsorption of Pb in the clay fraction were extremely high (maximum value: 322 581 mg kg-1) when compared to those of soil samples from other regions of the world. Adsorption occurred in two stages: first stage in which a high percentage of Pb was adsorbed, and second stage in which adsorption was lower. From an environmental point of view, soils with high contents of clay and amorphous minerals, ones usually associated with ornithogenic activity in Antarctica, should have greater efficiency in filtering Pb, thus reducing risks of leaching and groundwater contamination.

A systematic limnological survey of water bodies of Byers Peninsula (Livingston Island, South Shetland Islands) was carried out during the summer of 2001/02. Abundances of microbial plankton were determined which allowed a delineation of the pelagic food web structure. We also report the nutrient status of these lakes. We demonstrate the occurrence of a trophic gradient that extended from upland lakes (oligotrophic) to the coastal ones (eutrophic). The study shows that a lake's morphology regulates the relative importance of the pelagic and benthic habitats, whereas nutrient loads mainly determine its trophic status. Yet, some of the variability observed could be also a legacy of the landscape. Photosynthetic pigments analyses by high-performance liquid chromatography of the lake waters revealed a major occurrence of chlorophytes, chrysophytes and diatoms. The chlorophyll a concentrations in lakes in the central plateau were consistently lower (< 2.5 μg l-1) than coastal sites, which were one order of magnitude higher. Numbers of both bacterioplankton and autotrophic picoplankton also increased from inland to coastal sites. However, the relative role of autotrophic picoplankton in the total phytoplankton assemblage decreased with the increase in nutrients loads. Our results show that the trophic status clearly plays a significant role in structuring the pelagic communities of these lakes despite climatic constraints.

Time-series sediment traps were deployed to investigate the temporal evolution of particle fluxes in eastern and central Bransfield Strait, from December 1999–December 2000. Particle fluxes showed large seasonal variation at both trap sites. In eastern Bransfield Strait, summer mass fluxes were two orders of magnitude higher than winter mass fluxes, while in central Bransfield Strait, almost 99% of the annual mass flux (33 g m−2) was collected in a 40-day period from December–January. Export flux also exhibited a high regional variability. This regional variability is probably due to central Bransfield Strait's strong surface current, which carries most settling particles produced in the surface waters away from the mooring site during the low summer flux period. The relatively low biogenic silica to organic carbon ratios (a range of 0.29–1.4) and high lithogenic fluxes (41% of total mass flux) indicate that the growth of phytoplankton is not limited by the micronutrient iron in eastern Bransfield Strait. The annual flux of organic carbon in eastern Bransfield Strait was 6.8 g C −2, which is three times higher than the flux measured in central Bransfield Strait (2.2 g C −2). Organic carbon flux in eastern Bransfield Strait is relatively high for the Southern Ocean, possibly due to fast-sinking faecal pellets that lead to less decomposition of organic material in the water column. Calculations suggest that approximately 7.2% of the organic carbon produced at the surface in eastern Bransfield Strait is exported to a depth of 678 m. This exceeds the maximum calculated export of primary production to a depth of 1000 m in the Atlantic and Southern oceans.

Cosmogenic 10Be and 26Al measurements from bedrock exposures in East Antarctica provide indications of how long the rock surface has been free from glacial cover. Samples from the crests of Zakharoff Ridge and Mount Harding, two typical nunataks in the Grove Mountains, show minimum 10Be ages of 2.00 ± 0.22 and 2.30 ± 0.26 Ma, respectively. These ages suggest that the crests were above the ice sheet at least since the Plio–Pleistocene boundary. Adopting a ‘reasonable’ erosion rate of 5–10 cm Ma-1 increases the exposure ages of these two samples to extend into the mid-Pliocene. The bedrock exposure ages steadily decrease with decreasing elevation on the two nunataks, which indicates ~200 m decrease of the ice sheet in the Grove Mountains since mid-Pliocene time. Seven higher elevation samples exhibit a simple exposure history, which indicates that the ice sheet in the Grove Mountains decreased only ~100 m over a period as long as 1–2 Ma. This suggests that the East Antarctic Ice Sheet (EAIS) was relatively stable during the Pliocene warm interval. Five lower elevation samples suggest a complex exposure history, and indicate that the maximum subsequent increase of the EAIS was only 100 m higher than the present ice surface. Considering the uncertainties, their total initial exposure and subsequent burial time could be later than mid-Pliocene, which may not conflict with the stable mid-Pliocene scenario.