Vestfold Hills Research Articles

Radiocarbon dating of mumiyo from the Vestfold Hills, East Antarctica

Accelerator mass spectrometer (AMS) radiocarbon dating of mumiyo deposited by snow petrels at nesting sites in the Vestfold Hills indicates the colonies were established after 4800 yr BP (uncorrected for marine reservoir effect). Sites on the highest hills were probably established first, but colonisation took place long after initial deglaciation, which was well advanced by 12.5k yr BP. The reason for late colonisation is not known. Perhaps older sites exist, but current evidence suggests the main colonisation occurred after the mid-Holocene re-advance of the Sorsdal Glacier. (il3C values indicate a diet of krill.

A new species of Tetramitus in the benthos of a saline antarctic lake

A new amoeboflagellate, Tetramitus vestfoldii n. sp. was discovered in the microbial mat of Pendent Lake, Vestfold Hills, Eastern Antarctica. Isolates were examined using light microscopy, electron microscopy and molecular analysis of the small subunit ribosomal DNA (SSU rDNA). Microscopical observations revealed a markedly eruptive, limax amoeboid stage with a clear hyaline zone, whilst flagellates were tapered posteriorly with a cytostome and anterior rostrum from which 4 flagella of equal length arose. The SSU rDNA was sequenced. Alignment of the sequence with published sequences of some other amoeboflagellates revealed that this species is best placed within the Vahlkampfiidae. The T. vestfoldii SSU rDNA was found to show greatest similarity with that of T. rostratus , a species with which it also shares several structural characteristics. Inorganic nutrient measurements indicate that the benthos of Pendent Lake could be a favourable environment for a bacterivorous predator such as Tetramitus . Ice cover on Pendent Lake was seen throughout the study period and may have reduced light intensity in the microbial mat; a low light intensity would appear to be a requirement for this species. The new species is defined on the basis of a pronounced taper towards the posterior end in the flagellate stage, an intolerance to salt concentrations greater than 30 and phylogenetic resolution using SSU rDNA sequence comparisons.

Diversity of 746 Heterotrophic Bacteria Isolated from Microbial Mats from Ten Antarctic Lakes

Microbial mats, growing in Antarctic lakes constitute unique and very diverse habitats. In these mats microorganisms are confronted with extreme life conditions. We isolated 746 bacterial strains from mats collected from ten lakes in the Dry Valleys (lakes Hoare and Fryxell), the Vestfold Hills (lakes Ace, Druzhby, Grace, Highway, Pendant, Organic and Watts) and the Larsemann Hills (lake Reid), using heterotrophic growth conditions. These strains were investigated by fatty acid analysis, and by numerical analysis, 41 clusters, containing 2 to 77 strains, could be delineated, whereas 31 strains formed single branches. Several fatty acid groups consisted of strains from different lakes from the same region, or from different regions. The 16S rRNA genes from 40 strains, representing 35 different fatty acid groups were sequenced. The strains belonged to the alpha, beta and gamma subclasses of the Proteobacteria, the high and low percent G+C Gram-positives, and to the Cytophaga-Flavobacterium-Bacteroides branch. For strains representing 16 fatty acid clusters, validly named nearest phylogenetic neighbours showed pairwise sequence similarities of less than 97%. This indicates that the clusters they represent, belong to taxa that have not been sequenced yet or as yet unnamed new taxa, related to Alteromonas, Bacillus, Clavibacter, Cyclobacterium, Flavobacterium, Marinobacter, Mesorhizobium, Microbacterium, Pseudomonas, Saligentibacter, Sphingomonas and Sulfitobacter.

Survey of South Polar Skuas (Catharacta maccormicki) for Blood Parasites in the Vestfold Hills Region of Antarctica

Thin blood smears prepared from 125 South Polar skuas (Catharacta maccormicki) at breeding islands and feeding sites in the Vestfold Hills region of Antarctica between December 1999 and January 2000 did not contain hematozoa. These findings confirm results of previous smaller studies, and provide baseline data for this species.

An analysis of the limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica

The limnology and sedimentary diatom flora of fourteen lakes and ponds from the Windmill Islands, East Antarctica, is presented. Saline lakes, saline ponds and freshwater ponds are represented in this dataset. The Windmill Island lake diatom flora represents an intermediate floral assemblage between that of the freshwater lakes of the Larsemann Hills and the saline lakes of Vestfold Hills, East Antarctica. Variations within this assemblage are related to water chemistry variables in the Windmill Island lakes. In particular, a lakewater salinity/phosphate gradient can explain the variation observed in the sedimentary diatom flora of the lakes and ponds included in this study.

Impacts of geoscience research on the physical environment of the Vestfold Hills, Antarctica

Antarctic polar deserts can be of considerable scientific interest, but can also exhibit great environmental sensitivity. A variety of factors, including Australia's legal obligations under the Madrid Protocol, public expectations, certain research opportunities and ethical considerations, demand a very high standard of environmental protection. A survey outside the Davis Station limits in the Vestfold Hills, East Antarctica, identified 66 sites at which past human activities had left long term impacts on the physical environment. Nearly half of all observed impacts were the result of geoscientific research that had left old pit and trench sites, vehicular tracks, partly excavated palaeontological material, rock sampling and drilling sites, localised slope instability caused by disturbance, and discarded equipment and markers. Comparisons between rehabilitated sites and others where little, if any, rehabilitation appears to have been attempted suggest natural processes alone are generally insufficient to heal the damage, but that effective rehabilitation is often possible if undertaken immediately after the initial disturbance.

Impacts of geoscience research on the physical environment of the Vestfold Hills, Antarctica

Impacts of geoscience research on the physical environment of the Vestfold Hills, Antarctica

Viruses in the plankton of freshwater and saline Antarctic lakes

1. Virus‐like particle (VLP) abundances in nine freshwater to saline lakes in the Vestfold Hills, Eastern Antarctica (68° S) were determined in December 1999. In the ultra‐oligotrophic to oligotrophic freshwater lakes, VLP abundances ranged from 1.01 to 3.28 × 106 mL–1 in the top 6 m of the water column. In the saline lakes the range was between 6.76 and 36.5 × 106 mL–1. The lowest value was found in meromictic Ace Lake and the highest value in hypersaline Lake Williams. Virus to bacteria ratios (VBR) were lowest in the freshwater lakes and highest in the saline lakes, with a maximum of 23.4 in the former and 50.3 in the latter.2. A range of morphologies among VLP was observed, including phages with short (Podoviridae) and long tails, icosahedric viruses of up to 300 nm and star‐like particles of about 80 nm diameter.3. In these microbially dominated ecosystems there was no correlation between VLP and either bacterial numbers or chlorophyll a. There was a significant correlation between VLP abundances and dissolved organic carbon concentration (r=0.845, P < 0.01).4. The data suggested that viruses probably attack a spectrum of bacteria and protozoan species. Virus‐like particle numbers in the freshwater lakes were lower than values reported for lower latitude systems. Those in the saline lakes were comparable with abundances reported from other Antarctic lakes, and were higher than most values published for lower latitude lakes and many marine systems. Across the salinity spectrum from freshwater through brackish to hypersaline, VLP concentrations increased roughly in relation to increasing trophy.5. Given that Antarctic lakes have a plankton almost entirely made up of bacteria and protists, and that VLP abundances are high, it is likely that viruses play a pivotal role in carbon cycling in these extreme ecosystems.

Limnology and biology of saline lakes in the Rauer Islands, eastern Antarctica

The Rauer Islands contain more than fifty shallow lakes and small ephemeral ponds. Despite their proximity to the Vestfold Hills - one of the most diverse and intensively studied lake districts of eastern Antarctica - the lakes of the Rauer Islands have remained undescribed. In this study the physical and chemical limnology and biology of ten lakes is presented and their species-environment relationships explored using multivariate statistics. Analyses of chemical and biological data indicate that the Rauer Islands form a distinct limnological province amongst the lakes of the Prydz Bay oases. Salinities range from hypo- to hyper-saline with an ionic order close to that of seawater. Deviance from this order indicates either an earlier origin for some of the most hypersaline lakes when compared with the Vestfold Hills, more rapid evaporation vs precipitation or differences in the sources of ions resulting from isostatic history. With fluctuating salinities, winter water temperatures below –10°C, seasonal ice and slush formation, desiccation and high levels of solar radiation, the lacustrine environment presents considerable abiotic challenges for biological survival. Results indicate that there is little or no planktonic flora in the lakes and no zooplankton were encountered. Despite this, analyses of pigments, diatoms and other micro-algae revealed an active and diverse benthic biota characterized by filamentous cyanobacteria with interstitial algae. Thirty-eight diatom taxa, and a selection of Chlorophyta and Xanthophyta were detected amongst the cyanobacteria. Clusters in the diatom data correspond to salinity. Further analyses of the relationships between the biota and their environment revealed some of the strategies employed for survival. In particular, the synthesis of scytonemin was detected. This pigment is known to function as an extracellular UV sunscreen which protects cyanobacterial cells against damage by ultraviolet radiation. These results support the hypothesis that environmental extremes and biogeographical isolation control the biology of these lakes.

Site holds promise for ecosystem and biogeochemical investigations

Ellis Fjord, located in the Vestfold Hills of East Antarctica (68.5°S, 78°E), exhibits a range of environments, from essentially marine at its sea‐ward end, to permanently stratified basins with hypersaline brines at its inland end. The drainage basin of the fjord contains small areas of mosses and lichens, but no higher plants, and supplies fresh water to the fjord in ephemeral summer melt streams. Direct anthropogenic inputs are negligible or non‐existent, as are those from other mammals and birds. The fjord exhibits unusual biological and chemical properties, and offers the opportunity to study oceanic processes in isolation and at small scales. It also has the logistical advantage of proximity to the facilities of Australia's year‐round Davis research station.

Vegetation abundance and diversity in relation to soil nutrients and soil water content in Vestfold Hills, East Antarctica

Eighteen paired sites (adjacent to vs away from sea bird nests) and six transects (downslope of nests) across Vestfold Hills were sampled for vegetation, soil nutrients, soil water content and percent rock cover. Three moss and 17 lichen species were recorded, including a new record for the lichen Sarcogyne privigna. Sites adjacent to nesting areas generally had higher soil N and P than sites away from nesting areas; however, larger differences between site locations than within site pairs suggests considerable variation in nutrient input between nesting areas and/or redistribution of nutrients by meltwater around nests. Along transects below nesting sites, average soil total N declined from 0.22% to 0.05% within 2 m from the nest, while average total P declined more gradually from 2343 ppm P to 697 ppm P at 30 m from the nest. Moss and lichen species diversity and mean lichen species abundance were higher in sites adjacent to compared with away from nests. Data from site pairs and transects showed that lichen diversity and abundance increased with increasing soil nutrients, with soil P having a stronger influence than soil N. In contrast, soil nutrients were not significantly associated with moss diversity or abundance. Instead, number of moss species and abundance were positively associated with soil water content.

Fossil Rotifers and the Early Colonization of an Antarctic Lake

Early Holocene sediments from a continental Antarctic lake (Ace Lake, Vestfold Hills, East Antarctica) contained abundant fossil rotifers of the genus Notholca. The fossil is similar to specimens of Notholca sp. present in modern-day Ace Lake and other fresh and brackish lakes of the Vestfold Hills. Cyanobacteria and protists (chrysophyte cysts, dinoflagellate cysts, and rhizopod tests) were also recovered from the core samples. These sediments were deposited early in the freshwater phase of Ace Lake, soon after deglaciation of the area. The occurrence of this trophically diverse assemblage of organisms at an early stage in the evolution of the lake suggests either that they were part of an endemic Antarctic flora and fauna which pre-dated the last glacial maximum and survived in glacial refugia or that efficient intercontinental dispersal had occurred.

Variation in the ribosomal ITS-sequence of the lichens Buellia frigida and Xanthoria elegans from the Vestfold Hills, eastern Antarctica

Abstract:Thalli of the lichens Buellia frigida and Xanthoria elegans were collected from five different locations each 5–15km apart in the Vestfold Hills, Princess Elizabeth Land, eastern Antarctica. A further collection was made from Mawson Station, Mac Robertson Land, eastern Antarctica, 660km away. DNA was extracted from whole thalli and the ribosomal ITS region amplified by PCR using fungal specific primers. Resulting products were sequenced to gain an indication of whether or not variation was present within populations of lichen-forming fungi from continental Antarctica, and therefore of the availability of genetic resources to react to pressures such as climate change. Three genotypes ofB. frigida and two of X. elegans were detected in the Vestfold Hill collections. However, these differed by only one nucleotide position suggesting the presence of relatively little genetic variation, if the ITS region is indicative of the overall genome. Buellia frigida collected from Mawson Station had an identical ITS region sequence to the most common Vestfold Hills genotype, indicating that this species may have a low level of genetic variation across much of eastern Antarctica. In contrast, X. elegans collected from Mawson showed considerable genetic variation from the Vestfolds thalli, differing at 14·2% of nucleotide positions and had an identical ITS region sequence to an isolate from maritime Antarctica 4960km away. Samples from the Vestfold Hills formed a distinct cluster in a phylogenetic analysis of ITS sequences from a worldwide collection of X. elegans isolates.

Early Pliocene paleoenvironment of the Sørsdal Formation, Vestfold Hills, based on diatom data

Comparison of diatom data from modern surface sediments in Prydz Bay and the Kerguelen Plateau with diatom assemblages from the Sørsdal Formation, Vestfold Hills, indicates that the climate was warmer than present during the early Pliocene (4.5–4.1 Ma). Extant, sea-ice associated diatoms are significantly less abundant throughout the Sørsdal Formation than in the modern Antarctic coastal zone. Extant diatoms in the Sørsdal Formation, including Stellarima stellaris, Thalassiosira oliverana, Fragilariopsis sublinearis, Pseudo-nitzschia turgiduloides and Eucampia antarctica var. recta, are consistent with annual sea-surface temperatures (SST) of between −1.8 and 5.0°C. The presence of S. stellaris indicates that the summer SSTs were >3°C during some intervals. The absence of calcareous coccoliths and the silicoflagellate Dictyocha suggests that the upper limit for summer SST was <5°C. These data indicate that early Pliocene summer SST were between 1.6 and 3°C warmer than today. Abundant Chaetoceros cysts infer that stratified, open-water conditions were present during summer/spring. Ice sheet models suggest that warming of the magnitude evident in the Sørsdal Formation (≤3°C) should have resulted initially in increased snow accumulation and ice sheet growth. However, ice sheet growth was probably short-lived, as the long-term response to this warming in the early Pliocene resulted in a significant decrease in ice volume and deposition of the Sørsdal Formation. Other factors, such as increased basal-ice sliding and higher discharge (icebergs and melt-water), probably led to significantly elevated ablation rates from the Pliocene ice sheet, resulting in ice sheet retreat.

Late-Holocene East Antarctic climate trends from ice-core and lake-sediment proxies

A high-resolution record of evaporation for the last 650 years was derived from the diatom-salinity signal preserved in a sediment core taken from Ace Lake, Vestfold Hills (68° 28's, 78° 11'E), Antarctica. The seasonal oxygen isotope signal preserved in an ice core from Law Dome (66° 44'S, 112° 50'E), Antarctica, revealed a high-resolution summer temperature record for the same time period. The two proxies show highly correlated behaviour despite having significantly different climatic response mechanisms and a large geographic separation. The correlation observed between proxies based on such differing processes and analytical method ologies provides not only a climate record for the past 650 years that is both robust and regionally representative of coastal East Antarctica but also confirmation of the utility of reconstructions using these methods.

Diatom biostratigraphy and age of the Pliocene Sørsdal Formation, Vestfold Hills, East Antarctica

Fossil marine diatom assemblages from the Sørsdal Formation, a deposit of diatomaceous sand from Marine Plain in the Vestfold Hills, provide age and palaeoenvironmental information from a Pliocene coastal setting in East Antarctica. Benthic and meroplanktic diatom taxa suggest deposition in a shallow coastal embayment with water depths of 20–25 m. Diatom biostratigraphy indicates that the Sørsdal Formation belongs to the Fragilariopsis barronii Zone (4.5 to 4.1 Ma), through correlation to reference sections in the Ross Sea and Southern Ocean. Features of the other biota suggest higher sea-surface temperatures and reduced sea-ice cover, consistent with global records of higher sea level.

Adélie penguin colonies in eastern Prydz Bay: ‘biological indicators’ of exploration history and political change

AbstractTemporally and spatially increasing information on the distribution of Adélie penguin (Pygoscelis adeliae) breeding sites is used as an index of various national activities in eastern Prydz Bay, East Antarctica. Recorded instances of such sites are used to indicate both exploration and enhanced local knowledge. While Norwegians discovered the area (1935), and revisited it (1937), reports of penguins were minimal. The 1938 Ellsworth expedition added few details and the potential of Operation Highjump (1947) photographs to delimit breeding sites was never realised. Observations by Australian expeditioners from the mid-1950s onwards, supplemented to some extent by those from the Soviet Union, increased information substantially. When Davis station was established (January 1957), at least five breeding sites were known around eastern Prydz Bay. By 1973 this had increased to 23 or 24 sites, mostly north of the Sørsdal Glacier, which had apparently acted as a barrier to land-based exploration. Data available to 1980 showed 20 sites in the Vestfold Hills, added two in the Rauer Group, and omitted some recorded earlier. Ground surveys of the Vestfold Hills (November 1973) increased known sites slightly, discounted erroneous records, and massively increased numbers of individual colonies. In 1981 an air survey recognised 24 sites in the Vestfold Hills and increased those known to 47. In approximately the same period, official Soviet records showed perhaps four sites in the Vestfold Hills and another in the Rauer Group. Early reports provided poor estimates of breeding population sizes — totals of some 130,000 (or 174,200) pairs in the Vestfold Hills in 1973 are compared with perhaps 196,600 in 1981, with another 129,000 pairs to the south. By 1983 locations of breeding sites in the Vestfold Hills were well established, and this was achieved in southern Prydz Bay following publication of 1981 survey results.Progression of information regarding breeding sites in eastern Prydz Bay was slow. Initial Australian activities were slight following acceptance of its Antarctic Territory (1933). However, a Soviet Antarctic whaling fleet, uncertainty regarding American and Soviet intentions, and the imminent International Geophysical Year increased Australian interest. A station was established, local search areas expanded, and enhanced details regarding penguin breeding sites and colonies followed. Data reviews and surveys followed increasing international interest in southern ecosystems. Improved knowledge regarding the species' local populations reflected changing political agendas. Indeed, ‘knowledge’ itself gave early support to territorial claims. Participation in international surveys became an acceptable scientific endeavour, anticipated under Treaty agreements and promoted by associated organisations. In such fora, surveys and monitoring are expected, although not necessarily furthering the strength of existing claims.

Protozoan growth rates in Antarctic lakes

The growth rates of heterotrophic nanoflagellates (HNAN), mixotrophic cryptophytes, dinoflagellates and ciliates in field assemblages from Ace Lake in the Vestfold Hills (eastern Antarctica) and Lakes Fryxell and Hoare (McMurdo Dry Valleys, western Antarctica), were determined during the austral summers of 1996/1997 and 1997/1998. The response of the nanoflagellates to temperature differed between lakes in eastern and western Antarctica. In Ace Lake the available bacterial food resources had little impact on growth rate, while temperature imposed an impact, whereas in Lake Hoare increased bacterial food resources elicited an increase in growth rate. However, the incorporation of published data from across Antarctica showed that temperature had the greater effect, but that growth is probably controlled by a suite of factors not solely related to bacterial food resources and temperature. Dinoflagellates had relatively high specific growth rates (0.0057–0.384 h−1), which were comparable to Antarctic lake ciliates and to dinoflagellates from warmer, lower latitude locations. Temperature did not appear to impose any significant impact on growth rates. Mixotrophic cryptophytes in Lake Hoare had lower specific growth rates than HNAN (0.0029–0.0059 h−1 and 0.0056–0.0127 h−1, respectively). They showed a marked seasonal variation in growth rate, which was probably related to photosynthetically active radiation under the ice at different depths in the water column. Ciliates' growth rates showed no relationship between food supply and mean cell volume, but did show a response to temperature. Specific growth rates ranged between 0.0033 and 0.150 h−1 for heterotrophic ciliates, 0.0143 h−1 for a mixotrophic Plagiocampa species and 0.0075 h−1 for the entirely autotrophic ciliate, Mesodinium rubrum. The data indicated that the scope for growth among planktonic Protozoa living in oligotrophic, cold extreme lake ecosystems is limited. These organisms are likely to suffer prolonged physiological stress, which may account for the highly variable growth rates seen within and between Antarctic lakes.

Stratigraphy of the Pliocene Sørsdal Formation, Marine Plain, Vestfold Hills, East Antarctica

The Sørsdal Formation and one member, Graveyard Sandstone Member constitute a sedimentary sequence covering approximately 10 km2 of Marine Plain, Vestfold Hills, East Antarctica. The new Formation consists dominantly of friable diatomaceous siltstone and sandstone with dark limestone lenses. It is in situ, essentially horizontal, 7.2 m thick in its type section and lies less than 25 m a.s.l. Graveyard Sandstone Member occurs near the top of the formation, is highly lithified sandy diamictite, 30–50 cm thick and widespread through the Marine Plain region. Using diatoms, the Formation is Early Pliocene in age (Fragilariopsis barronii, 4.5–4.1Ma). The Graveyard Sandstone Member probably was deposited during the Gilbert Chron interval (lower Chron 2Ar or C3n. 1r) of reversed magnetic polarity. The Sørsdal Formation contains fossil cetaceans and a diverse and well-preserved invertebrate fauna. Foraminifera are rare partly because of diagenesis, but include Ammoelphidiella antarctica. No evidence of coeval terrestrial vegetation has been recovered. The deposit accumulated in a series of small bays probably in an environment warmer than exists in the region today. There is no lithological evidence of glacial influence except in Graveyard Sandstone Member that may represent local glacial influence in a shallow marine to intertidal environment.

Sublithic bacteria associated with Antarctic quartz stones

Quartz stone sublithic cyanobacterial communities are common throughout the Vestfold Hills, Eastern Antarctica (68°S 78°E) contributing biomass in areas otherwise devoid of any type of vegetation. In this study, the sublithic microbial community and underlying soil was investigated using a variety of traditional and molecular methods. Although direct epifluorescent counts of the sublithic growth (average 1.1 × 109 cells g−1 dry weight) and underlying soil (0.5 × 109 cells g−1 dry weight) were similar, sublith viable counts (2.1 × 107 cfu g−1 dry weight) were on average 3-orders of magnitude higher in the subliths. Enrichment and molecular analyses revealed the predominate cyanobacteria were non-halophilic, able to grow optimally at 15–20°C, and were related to the Phormidium subgroup with several distinct morphotypes and phylotypes present. Sublithic heterotrophic bacterial populations and those of underlying soils included mostly psychrotolerant taxa typical of Antarctic soil. However, psychrophilic and halophilic bacteria, mostly members of the alpha subdivision of the Proteobacteria and the order Cytophagales, were abundant in the sublithic growth film (20–40% of the viable count and about 50% of isolated individual taxa) but absent from underlying soils. It is suggested that quartz stone subliths might constitute a “refuge” for psychrophilic bacteria.