Search

The non-marine diatom flora of the Antarctic continent is currently being revised as recent work within the Maritime and Sub-Antarctic regions has unveiled a number of new endemic species. The under reporting of endemic species is partially due to the historic 'force-fitting' of Antarctic species into European names. Within East Antarctica, the Vestfold Hills are an extensively studied area known for their diversity of lakes spanning a salinity gradient, for whichDiatoms of the saline lakes of the Vestfold Hills, Antarcticaby Roberts & McMinn (1999) has a primary identification resource for over two decades. To determine if improved taxonomic resolution alters the ecological interpretation of these lakes, 30 prepared lake sediment samples first examined by Roberts & McMinn (1999) were re-analysed using an updated, fine-grained taxonomic approach. Our analyses confirmed the role of salinity and alkalinity in structuring Vestfold Hills diatom communities. Thus, the increased taxonomic resolution did not change the original ecological interpretation. However, the revised flora of the Vestfold Hills features 37 species endemic to the Antarctic Region, including members ofLuticola, SabbeaandHalamphora, among others. In total, 183 taxa across 38 genera were observed, in contrast to the 67 taxa reported in the original work. The revised flora, including a larger proportion of endemic species, may improve our understanding of the diatom community in general and has wider implications for both conservation and biodiversity estimates of Antarctica. More widely applied, these data can be incorporated into larger studies of Antarctic microbial biogeography and biodiversity.

The types and distributions of anthropogenic rubbish have been documented at Bunger Hills, East Antarctica. The area has been the site of scientific research stations from 1958 to the present. Rubbish types include deliberately or negligently discarded items (gas cylinders, broken glass), abandoned unserviceable equipment (boats, vehicles, scientific equipment), spills (chemicals, fuel, oil) and the slow collapse of old buildings. Some rubbish remained where it was left, while other material was redistributed by strong winds. Modern expeditioner training should limit the production of new rubbish, while inadvertent wind dispersal of rubbish from old station buildings could be minimized by better management of these structures and their surrounds. Buildings and other constructed items need ongoing maintenance if they are not to break down and be distributed by wind, or they should be removed within a reasonable period.

In this paper, we synthesize recorded observations of moss, lichen and bird species in Bunger Hills, East Antarctica, and assess the role of environmental controls, including sediment, salinity, moisture and geology, on species' distributions. The distribution of snow petrels (Pagodroma nivea) appears to be associated with geology; they nest by preference in crevices in bedrock outcrops around the margins of the hills or wherever jointed cliffs are found. South polar skuas (Catharacta maccormicki) are seen throughout Bunger Hills, where they nest and prey on snow petrels. Mosses and lichens were most abundant around the ice margins where fresh snow and ice meltwater are abundant. In the central area of Bunger Hills, where the highest salt concentration in sediments is found and exposure to abrasion by wind-driven mineral sand grains and ice particles is greatest, mosses and lichens are reduced in abundance and diversity. Exposure of parts of Bunger Hills from the ice sheet throughout the Last Glacial Maximum,c.20 kabp, means that some land and lakes could have acted as regional refugia and as a locus of recolonization of other ice-free areas.

The effect of increasing temperature from 30 to 60 °C on iron (II)-oxidation activity and microbial population development in columns was investigated. With respect to ‘mode of inoculation’, pre-inoculation of the ore with a mixed culture resulted in a shorter lag time during which the microorganisms established themselves on the ore. Inoculation with the bacteria was successful using current techniques but inoculation with hyper-thermophiles appears to require special enrichment and acclimatisation strategies to maximise success. Staged inoculation of bacteria at their preferred temperatures did not confer additional advantage. Inoculation during acid agglomeration was impacted by exposure to initially high acidity. With respect to population development, the combined tracking methods (signature lipids and denaturing gradient gel electrophoresis (DGGE)) provided valuable insights into the thermal tolerance of some microbial strains in a column environment and also detected new strains.

Antarctic arthropods (mites and springtails) have been the subject of numerous studies. However, by far, the most diverse and numerically dominant fauna in Antarctica are the limno-terrestrial microfauna (tardigrades, rotifers and nematodes). Although they have been the focus of several studies, there remains uncertainty of the actual number of species in Antarctica. Inadequate sampling and conserved morphology are the main cause of misclassification of species and underestimation of this diversity. Most species' distributional records are dominated by proximity to research stations or limited opportunistic collections, and therefore, an absence of records for a species may also be a consequence of the limitations of sampling. Limitations in fundamental knowledge of how many species are present and how widespread they are prevents any meaningful analyses that have been applied more generally to the arthropods within Antarctica, such as exploring ancient origins (at least pre-last glacial maximum) and tracking colonisation routes from glacial refugia. In this review, we list published species names and where possible the distribution of microfaunal (tardigrade, rotifer and nematode) species reported for Antarctica. Our current state of knowledge of Antarctic records (south of 60°S) includes 28 bdelloid rotifers, 66 monogonont rotifers, 59 tardigrades and 68 nematodes. In the light of the difficulties in working with microfauna across such geographical scales, we emphasise the need for molecular markers to help understand the 'true levels' of diversity and suggest future directions for Antarctic biodiversity assessment and species discovery. Refereed/Peer-reviewed

Antarctica is one of the harshest environments on the planet because of its extreme climatic conditions, with prolonged winters, freezing temperatures and lack of liquid water. While almost the entire continent (99.7%) is covered year round by snow and ice, some mountain peaks and coastal areas are ice-free and sustain life. Invertebrates dominate in this environment, but despite their obvious abundance, little is known of one major player, the rotifers. In this study, we examine the distribution and diversity of rotifers from across continental Antarctica using mitochondrial c oxidase subunit I DNA sequences, and compare to sequences extracted from specimens collected in limited locations in the Antarctic Peninsula (AP) and in Tierra del Fuego (TF) in South America. We identified rotifers of the Class Bdelloidea to be the most frequently sampled micro-organisms in soil and limno-terrestrial environments. From the Antarctic samples, 514 sequences were generated and 37 distinct lineages were identified (40 putative species based on the PTP model) within Philodina, Adineta and unidentified bdelloids (all currently considered endemic to Antarctica). Overall, we observed widespread ranges for some rotifers in continental Antarctica, many of them exceeding 2000 km. Only one bdelloid lineage (Adineta cf. gracilis) from continental Antarctica was also present in maritime Antarctica. No close similarities were found with worldwide locations, or amongst AP and TF. Our broad coverage across Antarctica shows unique lineages that may represent potential species surpassing what is presently known from morphology, even when conservative approaches are applied for species delimitation. Refereed/Peer-reviewed

Contrary to earlier beliefs, crustaceans are present in ice-covered lakes of Antarctica. Interpretation of the significance of this has been hampered by the absence of robust identification of taxa present. We examine cyclopoid copepods from three widely separated lakes. All belong to the michaelseni group of the genus Diacyclops, which is widespread across Continental Antarctica, but do not fit into any existing species. Two new species were identified from eastern Antarctica, D. walkeri from Pineapple Lake (Vestfold Hills) and D. kaupi from Transkriptsii Gulf (Bunger Hills). Most significant was a dense population of a new epibenthic species (D. joycei) associated with microbial mats in Lake Joyce, one of the smaller McMurdo Dry Valleys lakes. This represents the first record of adult cyclopoid copepods from the ice-covered lakes of the Transantarctic Mountains. Continental Antarctica is the centre of diversity for this group of crustaceans and we argue that this is better explained by persistence through past glacial advances rather than by recent post-glacial colonization. The existence of a species endemic to Lake Joyce but apparently absent from other Dry Valleys lakes is discussed in relation to our understanding of the history of the McMurdo Dry Valleys lakes and their faunas.

Deep Lake in Antarctica is a globally isolated, hypersaline system that remains liquid at temperatures down to -20 °C. By analyzing metagenome data and genomes of four isolates we assessed genome variation and patterns of gene exchange to learn how the lake community evolved. The lake is completely and uniformly dominated by haloarchaea, comprising a hierarchically structured, low-complexity community that differs greatly to temperate and tropical hypersaline environments. The four Deep Lake isolates represent distinct genera (~85% 16S rRNA gene similarity and ~73% genome average nucleotide identity) with genomic characteristics indicative of niche adaptation, and collectively account for ~72% of the cellular community. Network analysis revealed a remarkable level of intergenera gene exchange, including the sharing of long contiguous regions (up to 35 kb) of high identity (~100%). Although the genomes of closely related Halobacterium, Haloquadratum, and Haloarcula (>90% average nucleotide identity) shared regions of high identity between species or strains, the four Deep Lake isolates were the only distantly related haloarchaea to share long high-identity regions. Moreover, the Deep Lake high-identity regions did not match to any other hypersaline environment metagenome data. The most abundant species, tADL, appears to play a central role in the exchange of insertion sequences, but not the exchange of high-identity regions. The genomic characteristics of the four haloarchaea are consistent with a lake ecosystem that sustains a high level of intergenera gene exchange while selecting for ecotypes that maintain sympatric speciation. The peculiarities of this polar system restrict which species can grow and provide a tempo and mode for accentuating gene exchange.

The planktonic haptophyte Phaeocystis has been suggested to play a fundamental role in the global biogeochemical cycling of carbon and sulphur, but little is known about its global biomass distribution. We have collected global microscopy data of the genus Phaeocystis and converted abundance data to carbon biomass using species-specific carbon conversion factors. Microscopic counts of single-celled and colonial Phaeocystis were obtained both through the mining of online databases and by accepting direct submissions (both published and unpublished) from Phaeocystis specialists. We recorded abundance data from a total of 1595 depth-resolved stations sampled between 1955–2009. The quality-controlled dataset includes 5057 counts of individual Phaeocystis cells resolved to species level and information regarding life-stages from 3526 samples. 83% of stations were located in the Northern Hemisphere while 17% were located in the Southern Hemisphere. Most data were located in the latitude range of 50–70° N. While the seasonal distribution of Northern Hemisphere data was well-balanced, Southern Hemisphere data was biased towards summer months. Mean species- and form-specific cell diameters were determined from previously published studies. Cell diameters were used to calculate the cellular biovolume of Phaeocystis cells, assuming spherical geometry. Cell biomass was calculated using a carbon conversion factor for prymnesiophytes. For colonies, the number of cells per colony was derived from the colony volume. Cell numbers were then converted to carbon concentrations. An estimation of colonial mucus carbon was included a posteriori, assuming a mean colony size for each species. Carbon content per cell ranged from 9 pg C cell−1 (single-celled Phaeocystis antarctica) to 29 pg C cell−1 (colonial Phaeocystis globosa). Non-zero Phaeocystis cell biomasses (without mucus carbon) range from 2.9 × 10−5 to 5.4 × 103 μg C l−1, with a mean of 45.7 μg C l−1 and a median of 3.0 μg C l−1. The highest biomasses occur in the Southern Ocean below 70° S (up to 783.9 μg C l−1) and in the North Atlantic around 50° N (up to 5.4 × 103 μg C l−1). The original and gridded data can be downloaded from PANGAEA, doi:10.1594/PANGAEA.779101.

Accurate projections of future climate changes in regions susceptible to drought depend on a good understanding of past climate changes and the processes driving them. In the absence of longer term instrumental data, paleoclimate data are needed. In this study we develop a precipitation reconstruction for Rebecca Lagoon (41°11′S, 144°41′E), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements of sediment cores in the visible spectrum (380–730 nm) and instrumental precipitation record (1912–2009) was used to develop a model to reconstruct precipitation back in time. Results showed that the ratio of reflectance between 660 and 670 nm (i.e., reflectance at 660 nm/reflectance at 670 nm; a measure of pigment diagenesis) was significantly related to annual precipitation. A calibration model was developed (R = − 0.56, pauto < 0.001, RMSEP = 43.0 mm yr− 1, 5 year triangular filtered data, calibration period 1912–2009). Second, this calibration-in-time model was used to reconstruct late Holocene precipitation changes over the last ~ 3000 years. This showed relatively dry conditions from ca. 3100–2800 cal yr BP, wet conditions from ca. 2800–2400 cal yr BP, dry conditions from ca. 2400–2000 calyr BP, and variable conditions after this. Relatively wet conditions occurred from ca. 500 cal yr BP to the late AD 1800 s (ca. 50 cal. yr BP). The precipitation reconstruction indicates that conditions were relatively dry for the 20th century compared to the last ~ 3000 years. In particular, the dry period measured in recent decades is one of the most intense in at least the last 500 years. As precipitation in this region is primarily driven by the Southern Hemisphere westerly winds, these changes are discussed in terms of shifts in westerly wind strength and/or position.

Meltwater habitats in the Darwin Glacier region, Victoria Land (80°S), were sampled in December 2007 and January 2009 to characterize their microbial and metazoan ecology, nutrient status and geochemistry. Targeted areas included terrestrial ponds of the Grant Valley, Lake Wellman, Tentacle Ridge and Diamond Hill, and supraglacial ponds and cryoconite holes of the lower Darwin Glacier. Geochemistry ranged from Na-Cl dominated terrestrial ponds to Na-HCO3dominated, dilute supraglacial ponds and cryoconites. All showed the nitrate enrichment typical of inland ponds of Victoria Land (up to 13 g.l-1NO3-N), with some precipitating nitratine (NaNO3) salt. Elevated pH indicated ongoing photosynthetic processes. Benthic microbial mats were thin and poorly developed, dominated by oscillatoriacean cyanobacteria. Nitrogen-fixing genera were generally absent and diatoms were rare. A large (20 μm long)Cyanothecespecies was the most abundant cyanobacterium in the water and in sediments of the cryoconites. DNA finger-printing identified distinct differences in cyanobacterial and bacterial community structure between the cryoconites, terrestrial ponds and ponds on glacial margins. Eleven metazoan species were identified, with rotifers being the most abundant. Pond substrate (terrestrial rock, ice-cored moraine or supraglacial ice) proved to be a more significant influence on biogeochemistry than other aspects of geography or climatic conditions.

A new spine-bearing Pinnularia species, Pinnularia gemella sp. nov., is described from a sediment core taken on the Antarctic Livingston Island (South Shetland Islands, southern Atlantic Ocean). The morphology of this species was examined using scanning electron microscopy. The species is easily recognizable by the presence of a continuous row of small, spathulate spines on one side of the valve. Using these interlocking spines, the species forms small colonies with the frustules lying in juxtaposition. The morphology and colonial form of the new species is compared to all other spine-bearing species such as P. sofia Van de Vijver & Le Cohu andlor colonial species such as P. cardinaliculus (A. Schmidt) Cleve. The ecology of the new species is derived from the ecological preferences of the associated flora.

Evidence is provided from a sediment core from saline Abraxas Lake, Vestfold Hills, that indicates that the lake existed through the Last Glacial Maximum. It can therefore be concluded that at least part of the Vestfold Hills also remained ice-free through the Last Glacial Maximum, or at most was covered by a thin, non-erosive cold-based ice sheet. The evidence for the continued existence of Abraxas Lake includes a 14C date that significantly predates the Last Glacial Maximum (though this cannot be considered direct proof of the existence of the lake prior to the Last Glacial Maximum); the presence of saline porewater throughout the core, including in compacted sediments deposited during the glacial period, which implies that the lake obtained its salt prior to any Holocene marine highstand; and the occurrence of marine-derived fauna from the onset of significant biological activity late in the Pleistocene. The occurrence of ice-free land in the Vestfold Hills and similar oases suggests that the margin of the polar ice cap did not reach far beyond its current position at the Last Glacial Maximum, at least in regions now occupied by these oases.

Paratrochammina minutissima n. sp. is described from Abraxas and Ace Lakes in the Vestfold Hills, East Antarctica. The species is characterized by very small size (120 mm diameter), 4K chambers in the final whorl, weak adherence of particles to the tectin chamber lining and a relatively prominent proloculus. Similar species occur in the fully marine environment and often in the abyssal ocean. Subfossil tests were observed in sediment cores from Abraxas Lake and nearby Ace Lake. Apparently, living specimens also occurred in plankton samples from Abraxas Lake, possibly indicating a lifestyle partly attached to zooplankton or floating debris, or floating unattached on density surfaces within the meromictic lake. The distribution of subfossil Paratrochammina minutissima in the sediments of Ace Lake was consistent with a marine origin for the species, while the distribution in the Abraxas Lake sediment indicated that the lake might predate the last glacial maximum.

A series of nutrient-amended microcosms was used to investigate changing microbial communities during biodegradation in hydrocarbon-contaminated Antarctic soils at 4, 10 and 42 °C. Although sample heterogeneity resulted in no statistically significant reduction in total petroleum hydrocarbons, biodegradation ratios indicate significant mineralisation. The number of culturable bacterial grown at 4 and 10 °C increased from 3 × 105 g− 1 dry soil then peaked after 5 days incubation at 5 × 107 g− 1 dry soil, before decreasing to and remaining stable at ca. 2 × 107 g− 1 dry soil. While the bacterial population grown at 42 °C was initially a minor constituent of the total culturable bacterial population, after 40 days there was similar numbers of bacteria estimated at all temperatures investigated. Denaturing gradient gel electrophoresis indicated significant differences in the microbial community between the 4 and 10 °C and the 42 °C microcosms. Numerically dominant culturable hydrocarbon degrading bacteria were isolated at each temperature; 16S rRNA gene sequences identified the 4 and 10 °C isolates as Pseudomonas spp., and the 42 °C isolates as Paenibacillus spp. Fatty acid methyl ester profiles of the cultures were consistent with these identifications. The results from this study indicate that bioremediation treatments will substantially alter the soil microbial ecosystem. All isolates from this study were capable of growth at 28 °C. The presence of autochthonous hydrocarbon degrading microbes capable of growth at higher temperatures introduces the possibility of in situ remediation treatment options involving heating (ca. 10–28 °C) to accelerate the rate of hydrocarbon degradation.

A new species of rotifer, Rhinoglena kutikovae n.sp. (Monogononta: Epiphanidae), is described from a freshwater lake in the Bunger Hills, East Antarctica. The new taxon is characterized by the following combination of characters: body conical to vase-shaped; a single toe; distal foot pseudosegment bulged; tail prominent, semi-circular; two small spherical pedal glands with common duct, forming a complex with caudal ganglion; trophi with seven major teeth with offset head and two smaller teeth without offset head. The new species is compared with R. fertoeensis, R. frontalis and R. tokioensis, of which scanning electron microscopic information is presented of the trophi. R. kutikovae n.sp. is probably a relict species that survived Quaternary glaciations in glacial lacustrine refugia on the Antarctic continent.

Remains of tardigrades have rarely been reported to preserve in sediments, resulting in the absence of important ecological and biogeographic information that they could provide. However, a study of faunal microfossils in Antarctic lake sediment cores has shown that tardigrade eggs and occasionally exuvia can be abundant. Eggs from at least five tardigrade species were identified in sediment cores from six lakes from across the continent, with abundances up to 6,000 (g−1 dry wt.). It is likely that the cold temperatures and absence of benthic grazers in Antarctic lakes results in particularly good preservation conditions, though it may also be a function of population density. The conservation of tardigrade eggs and exuvia in lake sediments enables a better understanding of paleodistributions and effects of environmental changes for this phylum that cannot otherwise be obtained.

The invertebrate fauna of many Antarctic ice-free areas, even those close to permanent research stations, can be poorly known. Here we describe some nematodes from freshwater and saline, marine-derived lakes of the Vestfold Hills, East Antarctica. The freshwater lakes contained the widespread East Antarctic endemic species, Plectus frigophilus Kirjanova, 1958. The saline lakes were inhabited by two recently described species, Halomonhystera halophila Andrassy, 2006 and Halomonhystera continentalis Andrassy, 2006, and by a new species described in this report, Hypodontolaimus antarcticus sp. n. Originally marine but now brackish Highway Lake contained a nematode fauna with both freshwater and marine-derived components. The nematode fauna of Antarctica now consists of 54 named species, 22 of which are found in East Antarctica.

The origins of the freshwater fauna that inhabits Antarctic lakes are poorly known. The species present today could be relict species that have survived Quaternary glaciations on the continent, or Holocene migrants from more temperate regions. One approach to investigating these questions is to study faunal microfossils in lake sediment. This approach was applied to a 293 cm sediment core from Lake Boeckella, located at the northern tip of the Antarctic Peninsula. The microfossils indicated that most of the metazoan species that occur in the lake today have been present since soon after the lake�s formation c. 5.5 ka ago. In particular, the centropagid copepod Boeckella poppei (Mra´zek) has been present throughout the lake�s history, suggesting a local source for this species. The development of biodiversity in the lake with time was in general more consistent with local (Antarctic) rather than distant (South American) sources, though an alternative explanation is that dispersal to Antarctica was more efficient in the mid-Holocene. Evidence of dispersal from extra-continental sites comes from the scattered occurrence throughout the core of Eubosmina chilensis (Daday), a South American species that does not reach the Antarctic or the sub- Antarctic islands at present, and which failed to establish a permanent population in the lake.

Aim There is no previous direct evidence for the occurrence of lacustrine refuges for invertebrate fauna in Antarctica spanning the Last Glacial Maximum (LGM). In the absence of verified LGM lacustrine refuges many species are believed to result from Holocene dispersal from sub-Antarctic islands and continents further north. If freshwater lake environments were present throughout the LGM, extant freshwater species may have been associated with Antarctica prior to this glacial period. This study looked at faunal microfossils in a sediment core from an Antarctic freshwater lake. This lake is unusual in that, unlike most Antarctic lakes, the sediment record extends to c. 130,000 yr bp, i.e. prior to the LGM. Location Lake Reid, Larsemann Hills, East Antarctica (76°23' E; 69°23' S). Methods Palaeofaunal communities in Lake Reid were identified through examination of faunal microfossils in a sediment core that extended to c. 130,000 yr bp. Results Ephippia and mandibles from the cladoceran Daphniopsis studeri and loricae of the rotifer Notholca sp. were found at all depths in the sediment, indicating that these two species have been present in the lake for up to 130,000 years. Copepod mandibles were also present in the older section of the core, yet were absent from the most recent sediments, indicating extinction of this species from Lake Reid during the LGM. Main conclusion The presence of D. studeri and Notholca sp. microfossils throughout the entire Lake Reid core is the first direct evidence of a glacial lacustrine refugium for invertebrate animals in Antarctica, and indicates the presence of a relict fauna on the Antarctic continent.

We profiled five ice-covered lakes and two ice-covered fiords of Ellesmere Island at the northern limit of High Arctic Canada to examine their environmental characteristics, and to evaluate the long-term limnological consequences of changes in their surrounding landscape through time (landscape evolution). All of the ecosystems showed strong patterns of thermal, chemical, and biological stratification with subsurface temperature maxima from 0.75 to 12.15 °C; conductivities up to 98.1 mS cm–1 (twice that of seawater) in some bottom waters; pronounced gradients in nitrogen, phosphorus, pH, dissolved inorganic and organic carbon, manganese, iron, and oxygen; and stratified photo synthetic communities. These ecosystems form an inferred chronosequence that reflects different steps of landscape evolution including marine embayments open to the sea, inlets blocked by thick sea ice (Disraeli Fiord, Taconite Inlet), perennially ice-capped, saline lakes isolated from the sea by isostatic uplift (Lakes A, C1, C2), and isolated lakes that lose their ice cover in summer. The latter are subject to entrainment of saline water into their upper water column by wind-induced mixing (Lake Romulus; Lake A in 2000), or complete flushing of their basins by dilute snowmelt (Lake C3 and Char Lake, which lies 650 km to the south of the Ellesmere lakes region). This chronosequence illustrates how changes in geomorphology and other landscape properties may influence the limnology of coastal, high-latitude lakes, and it provides a framework to explore the potential impacts of climate change.

Species identification of copepods in lake sediments is often difficult because their remains lack diagnostic features. It is therefore not easy to track changes in copepod biodiversity in lakes through time. We report a method for the isolation, amplification, and identification of copepod DNA from whole lake sediments formed in the early Holocene to the present. The method, which involves amplification of a short (~300 base pair) DNA sequence that varies between copepod species, provides a new approach to the study of copepod paleobiodiversity. Successful amplification of copepod DNA was possible in samples as old as 9950 calibrated 14C y BP. Attempts failed to recover DNA from a sediment sample ca 65,000 years old. In most cases the species identified in the sediments matched those of extant lake populations, but analysis of early-mid Holocene sediments from one lake revealed a species that is not present today. We were able to recover copepod DNA from core samples stored at -20 degrees C, at 4 degrees C, and preserved with polyethyleneglycol.

The lipid composition was determined for 5 species of polychaete annelids collected by the Deep Submergence Vehicle ALVIN from high temperature chimneys at the 2500 m depth hydrothermal vent field of the East Pacific Rise. These are the first lipid biomarker analyses reported for these hydrothermal vent polychaetes. Lipid content was low in all samples (1.6–35.9 mg g –1 wet mass) and was dominated by polar lipid (78–90% of total lipid) with 8–19% sterol (ST), and very low storage lipid (triacylglycerol and wax ester). Total polyunsaturated fatty acids (PUFA) were moderately high (22–31% of total fatty acids (FA)) with extremely low or no docosahexaenoic acid (DHA, 22:6(n-3)). Eicosapentaenoic acid (EPA, 20:5(n-3)) levels were 5–6% in Alvinella pompejana and A. caudata and 10.3–13.7% in an errantiate polychaete (likely Hesionidae) and Hesiolyra bergii . There were greater PUFA and a greater EPA/AA (AA is arachidonic acid, 20:4(n-6)) ratio in the anterior versus the posterior half of A. pompejana , which may correlate to the strong temperature gradient reported in its tube. Total nonmethylene interrupted diunsaturated fatty acids (NMID) were 4–9% of total FA for most polychaete species and included several 20:2 and 22:2 components. The principal monounsaturated fatty acids (MUFA) included 18:1(n-7)c (14–19%), 16:1(n-7)c (2.6–10%) and 20:1(n-11)c (3–7% of total FA). These polychaete species may desaturate and elongate the bacterial-derived 18:1(n-7)c to obtain the essential FA EPA and AA. The major ST in the polychaetes is cholesterol (89–98% of total ST) with less cholesterol in the gut contents of A. pompejana . Other ST included 24-ethylcholesterol (1.5–5% of total ST) with lesser amounts of 24-methylenecholesterol, desmosterol, lathosterol, 24-methylcholesterol, 24-ethylcholesterol, and the stanols dehydrocholestanol and cholestanol. The high ST levels could play a role in thermal adaptation of membranes at the hydrothermal vent environment. Differences in the FA profiles separated the closely related species A. pompejana and A. caudata from Paralvinella grasslei , H. bergii , and the errantiate polychaete (likely Hesionidae).

The sediment record of the fauna of Ace Lake, a saline meromictic lake in the Vestfold Hills, Antarctica, consists of copepod eggs, spermatophores and exoskeletal fragments, rotifer and tintinnid loricae, and foraminiferal and folliculinid tests. The relative abundance of these remains, along with other characteristics of the core, allows the development of a coherent picture of the progress of Ace Lake from a species-poor, freshwater lake early in the Holocene to a biodiverse marine basin following a marine transgression. Subsequent sea level fall reformed Ace Lake as a saline lake and productivity initially increased after isolation. After a major event, possibly associated with overturn of the meromictic lake, biodiversity and productivity decreased, and have continued to do so until the present.

Cultivable strains were identified from sulfate-reducing fluidized-bed reactors (FBR) treating acidic metal-containing wastewater. The FBR-communities were further characterized using culture-independent phenotypic markers, phospholipid fatty acid (PLFA) profiling. After morphological screening of 128 bacterial strains and partial sequencing of 55 strains, 17 distinct phylogenetic types were identified and characterized further. A total of 14 and 6 different bacterial strains were isolated from ethanol- and lactate-fed FBRs, respectively. Sequencing of the 16S rRNA gene showed that these strains were affiliated with members of the δ-Proteobacteria, Firmicutes and Bacteroidetes The strains were affiliated with members of the genera Desulfovibrio, Desulfotomaculum, Desulfobulbus, Desulfitobacterium, Clostridium, Caloramator, Oxobacter, and Bacteroides. Many of the strains were only distantly related to previously described species and, thus, may represent novel species or genera. A number of the strains wer...

New populations of the two species of calanoid copepods known to inhabit freshwater lakes in East Antarctica, Boeckella poppei (Mrázek, 1901) and Gladioferens antarcticus Bayly, 1994, have recently been discovered. The morphology of the populations of B. poppei showed significant differences, notably a reduction in the armature of the male fifth leg, when compared with typical specimens from the Antarctic Peninsula and South America. Gladioferens antarcticus had previously been recorded from a single lake in the Bunger Hills, but has now been recorded from three further lakes in this region. A recent review of Antarctic terrestrial and limnetic zooplankton suggested that neither of these species can be considered an East Antarctic endemic, with B. poppei being listed as a recent anthropogenic introduction and G. antarcticus a ‘marine interloper’. We conclude differently: B. poppei has been present in isolated populations in East Antarctica for significant lengths of time, possibly predating the current interglacial, while G. antarcticus is a true Antarctic endemic species whose ancestors have been present in the region since before Australia separated from Antarctica.

The requirement for an Antarctic component to the 2001 Australian State of the environment report initiated the development of a state of the environment system designed to remain current, yet minimize the resources required for maintenance. A series of environmental indicators was developed and refined by a group of experts during a period of 18 months. A simple descriptive template and data for each indicator were incorporated into a web-accessible database system called SIMR (System for Indicator Management and Reporting). The system captures indicator data either dynamically from sensors or by web input by indicator custodians. The system also prompts custodians for regular input of evaluations of indicator status. The system (http://www-aadc.aad.gov.au/soe) has been an effective framework for considering all aspects of state of the environment reporting and a practical tool in research and operational aspects of the Australian Antarctic Division.

Antarctica contains some of the most challenging environmental conditions on the planet due to freezing temperatures, prolonged winters and lack of liquid water. Whereas 99.7% of Antarctica is permanently covered by ice and snow, some coastal areas and mountain ridges have remained ice-free and are able to sustain populations of microinvertebrates. Tardigrades are one of the more dominant groups of microfauna in soil and limno-terrestrial habitats, but little is known of their diversity and distribution across Antarctica. Here, we examine tardigrades sampled from across an extensive region of continental Antarctica, and analyse and compare their partial mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequences with those from the Antarctic Peninsula, maritime and sub-Antarctica, Tierra del Fuego and other worldwide locations in order to recognise operational taxonomic units (OTUs). From 439 new tardigrade COI sequences, we identified 98 unique haplotypes (85 from Antarctica) belonging to Acutuncus, Diphascon, Echiniscus, Macrobiotus, Milnesium and unidentified Parachela. Operational taxonomic units were delimited by Poisson tree processes and general mixed Yule coalescent methods, resulting in 58 and 55 putative species, respectively. Most tardigrades appear to be locally endemic (i.e. restricted to a single geographic region), but some (e.g. Acutuncus antarcticus (Richters, 1904)) are widespread across continental Antarctica. Our molecular results reveal: (i) greater diversity than has previously been appreciated with distinct OTUs that potentially represent undescribed species, and (ii) a lack of connectivity between most OTUs from continental Antarctica and those from other Antarctic geographical zones. Refereed/Peer-reviewed

Thermophilic acidophilic Archaea were enriched from samples collected from geothermally active sites in Papua New Guinea. Pure cultures (JP2 and JP3) were obtained from mixed culture enrichments and were characterised and tested for their bioleaching ability. All cultures possessed Sulfolobus -like morphology, and the presence of distinctive cyclized tetraether lipids. The two pure cultures were identified by their 16S rRNA gene sequences as being most closely related to Sulfolobus solfataricus . Each isolate was able to oxidise both Fe 2+ and sulphur, and grow on both pyrite and chalcopyrite under autotrophic conditions. Leaching experiments showed that the isolates were capable of rapidly leaching a chalcopyrite concentrate (up to 91% Cu release in 108 h). Optimal temperatures for growth and chalcopyrite leaching were determined for each strain. Chalcopyrite dissolution rates for JP2 at different temperatures were determined using a previously described kinetic model. An Arrhenius plot to investigate the relationship between dissolution rate and temperature, showed that for JP2, an increase in temperature from 70 to 83 °C resulted in a 6.6-fold rate increase. Studies with both mixed and pure cultures showed that these cultures were capable of rapidly leaching a chalcopyrite concentrate at very high temperatures (up to 90 °C), but also were capable of bioleaching at 50 °C. These thermophilic acidophiles possess the ability to bioleach over a wide range of temperatures. They are potentially well suited to industrial leaching applications where considerable temperature fluctuations limit the growth of other non-thermophilic bioleaching microorganisms.

Further details regarding the landing made by Klarius Mikkelsen in the Tryne Islands, Vestfold Hills, East Antarctica, are given, being derived mainly from newspaper accounts made by Leif S0rsdal. All involved in the landing on 20 February 1935 have been identified, details of material left in the depot under the raised flag are given, and more extended information relating to the voyage to and from the site and the area generally are presented. Some comparison is made between Sørsdal's accounts and others. While the national importance of the landing was commented on, only S0rsdal apparently realised (but did not state) the insular nature of the site. Recent observations at the site suggest that its location is 68°22′38.22″S, 78°24′50.10″E, rather than that previously stated; bracing of the flagpole itself has been modified at some stage since its erection. Finally, some discussion is made regarding on-going questions relating to the accepted time on board ship, and possible consequences of errors.

Thick ice cover is a feature of cold-temperate, polar, and alpine lakes and rivers throughout much of the year. Our observations from Canadian lakes and rivers across the latitudinal gradient 46‐808N show that their overlying ice contains low concentrations of dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) relative to the underlying waters. The CDOM exclusion factor (water/ice) ranged from 1.4 to 114 and was typically greater than twice the exclusion factor for inorganic solutes. Application of synchronous fluorescence analysis to lake ice samples and experimentally frozen lakewater indicated that only less complex, lower molecular weight molecules were retained within the ice. Consistent with this analysis, DOC-specific absorption showed that the DOC in the ice was generally less colored than that in the underlying waters. The reduced CDOM absorption within the ice allowed relatively high ultraviolet (UV) transmission despite the elevated scattering within the ice and resulted in UV diffuse attenuation coefficients up to eight times lower in the ice than in the underlying waters. This relatively low attenuation by the ice would cause organisms trapped near the surface by inverse stratification to experience high UV exposure prior to ice breakup. The ice exclusion effect gives rise to a concentrated zone of CDOM and DOC that is likely to favor heterotrophic and mixotrophic processes and influence biogeochemical interactions.

Epishelf lakes, positioned between ice-free areas and floating ice shelves or glaciers, are unusual tidal, but largely freshwater, environments found in both the Arctic and the Antarctic. The greatest concentration of these lakes is in the Bunger Hills, East Antarctica (66°S, 100°E). We present and discuss temperature and salinity profiles for five epishelf lakes from this region, most of which show unusual properties. White Smoke Lake is fresh and cold (

An extensive terrestrial drainage system, centred on Algae Lake in southern Bunger Hills, is described. The 25-km-long Algae River is the third longest known in Antarctica after Onyx River (Wright Valley, Victoria Land) and Druzhby River (Vestfold Hills, Queen Elizabeth Land). Algae River receives meltwater from the Antarctic ice sheet, Apfel Glacier, and ephemeral and permanent snow banks in the ice-free area of the Bunger Hills. Water flows through a series of epiglacial lakes before reaching the extensive Algae Lake, which in turn has an outlet to Transkriptsii Gulf, a largely fresh-water, tidal epishelf lake connected to the ocean under the Edisto Ice Tongue and Shackleton Ice Shelf. Total flow from Algae Lake was estimated to be greater than 1 x 107m3a-1from data collected in the 1986/87 summer. Some portions of the drainage system that were flowing during the 1946/47,1985/86, 1986/87, 1994/95, 1995/96, and 1998/99 summers were not flowing during the 1999/2000 summer, indicating the variable nature of discharge in the river and emphasising that parts of the drainage network may become disconnected readily.

The geochemical processes occurring within meromictic Lake A (maxdepth 120 m) on northern Ellesmere Island, Canada, were investigated to determinethe history of the lake and to provide a baseline for future studies. The lake contained seawaterdiluted by freshwater input that had been mixed prior to the lake's isolation from tidalaction. Input of freshwater after isolation of the lake created vertical stratification resultingin the creation of distinct oxic, suboxic and anoxic zones. Dissolved oxygen was present to 13 m,and sulphide beneath 32 m. Manganese and iron cycling dominated the redox chemistrybetween these depths. Total manganese concentrations reached 176 μM, higher thanin most other natural stratified lake or marine environments.

Lake A is a meromictic, perennially ice-covered lake located at the northern limit of North America (latitude 83°N, Ellesmere Island, Canada). In early June 1999, only 0.45% of incident photosynthetically available radiation (PAR) was transmitted through its 2-m ice and 0.5-m snow cover. Removal of snow from 12 m2 increased PAR under the ice by a factor of 13 and biologically effective ultraviolet radiation (UVR) by a factor of 16 (from 0.4% to 6.3% of incident). The diffuse attenuation coefficient (Kd) for UVR was substantially lower in the ice than in the underlying freshwater (e.g., 50% lower at 320 nm), indicating the exclusion of chromophoric dissolved organic matter (CDOM) during freeze-up or the subsequent degradation of CDOM retained in the ice. Peak phytoplankton concentrations occurred immediately under the ice, and a broad maximum of photosynthetic sulfur bacteria and associated sulfur particles was observed over the depth interval 20–45 m at

Changes in the concentration of chromophoric dissolved organic matter (CDOM) were determined over short (hours to days) and medium (weeks) time scales during summer in a shallow, polymictic lake in subarctic Quebec, Canada. CDOM fluorescence (F CDOM ) decreased linearly from mid-June until early August, consistent with the zero-order kinetics expected for photodegradation of organic matter in a regularly mixed lake in which most of the photochemically-active radiation is absorbed by CDOM. A major rainfall event then resulted in a sharp increase in F CDOM back to levels recorded at the start of the study. These changes showed that CDOM concentrations were controlled by the balance between catchment inputs and subsequent photodegradation processes within the lake. Shorter term changes in CDOM concentration were monitored by measuring the penetration of ultraviolet radiation (UVR) using a Satlantic TACCS system moored near the center of the lake and set to monitor down-welling 380 nm irradiance at 10 min intervals. The diffuse attenuation coefficient K d (380) decreased by 12 % during the deployment indicating increased penetration of UVR and the change paralleled the drop in F CDOM over the same period. Many of the daily records showed a significant decline in K d (380) in the near-surface waters over the course of the morning and early afternoon indicating diurnal photobleaching of CDOM, and an increase later in the day consistent with the breakdown of the diurnal thermocline and entrainment of deeper waters. The results illustrate the short and medium term dynamics of CDOM, the importance of diurnal stratification and mixing for photochemical processes, and the variability that aquatic organisms must experience in UV exposure in their natural environment.

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.

The zooplankton assemblages of Lake A and Disraeli Fjord, northern Ellesmere Island (83°N, 75°W), were surveyed in early summer 1999. In permanently ice-covered Lake A, two glacial relict calanoid copepod species (Drepanopus bungei and Limnocalanus macrurus) were found in the top 30 m. All developmental stages of the more abundant D. bungei were present, whereas only adults of L. macrurus were found. Analysis of gut contents showed that L. macrurus preyed upon the smaller species. A net tow sample of zooplankton from Disraeli Fjord was mainly composed of D. bungei and L. macrurus, along with two marine cyclopoid copepods (Oncaea borealis and Oithona similis). These two zooplankton communities occur within unusual environments that are strongly influenced by perennial ice and snow. They will be subject to major habitat disruption should the current warming trends continue in the north polar region.

Early explorers in the Canadian high Arctic described a fringe of thick, landfast ice along the 500-km northern coast of Ellesmere Island. This article shows from analyses of historical records, aerial photographs, and satellite imagery (ERS-1, SPOT, RADARSAT-1) that this ancient ice feature (‘Ellesmere Ice Shelf’) underwent a 90% reduction in area during the course of the twentieth century. In addition, hydrographic profiles in Disraeli Fiord (83°N, 74°W) suggest that the ice-shelf remnant that presently dams the fiord (Ward Hunt Ice Shelf) decreased in thickness by 13 m (27%) from 1967 to 1999. Mean annual air temperatures at nearby Alert station showed a significant warming trend during the last two decades of this period, and a significant decline in the number of freezing degree days per annum. The ice-dammed fiord provides a stratified physical and biological environment (epishelf lake) of a type that is otherwise restricted to Antarctica. Extensive meltwater lakes occur on the surface of the ice shelf and support a unique microbial food web. The major contraction of these ice–water habitats foreshadows a much broader loss of marine cryo-ecosystems that will accompany future wanning in the high Arctic.

The presence of crustaceans in some Antarctic lakes adds a level of complexity to the food webs of these environments. The grazing pressure of the crustaceans on phytoplankton and other protists, and the role they play in controlling food web structure, has not yet been examined in any detail. This paper presents the first data on grazing pressure of crustacean zooplankton in continental Antarctic lakes. In this study the grazing rates of Paralabidocera antarctica in saline Ace Lake, Vestfold Hills, were assessed using a radio-tracer method. Clearance rates ranged from approximately 1 to 8 ml ind.−1 day−1, depending on developmental stage. Due to their high abundance, nauplii exhibited the highest daily carbon ingestion rates. The population cleared about 3% of the water column per day, accounting for a significant fraction of primary production. P. antarctica has a considerable impact on the carbon cycle in Ace Lake and, by inference, in the other lakes in which it occurs.

The Ward Hunt Ice Shelf (83 degrees N, 74 degrees W) is the largest remaining section of thick (10 m) land-fast sea ice along the northern coastline of Ellesmere Island, Canada. Extensive meltwater lakes and streams occur on the surface of the ice and are colonized by photosynthetic microbial mat communities. This High Arctic cryo-ecosystem is similar in several of its physical, biological and geochemical features to the McMurdo Ice Shelf in Antarctica. The ice-mats in both polar regions are dominated by filamentous cyanobacteria but also contain diatoms, chlorophytes, flagellates, ciliates, nematodes, tardigrades and rotifers. The luxuriant Ward Hunt consortia also contain high concentrations (10(7)-10(8) cm-2) of viruses and heterotrophic bacteria. During periods of extensive ice cover, such as glaciations during the Proterozoic, cryotolerant mats of the type now found in these polar ice shelf ecosystems would have provided refugia for the survival, growth and evolution of a variety of organisms, including multicellular eukaryotes.

We compared the lipid stores of coastal and lacustrine populations of the copepod Par- alabidocera antarctica over a complete developmental cycle. The life cycle of the coastal population, which was reflected in their pattern of lipid storage, was coupled closely to the growth of sea ice. Nauplii entered the sea ice in early autumn and overwintered predominantly as the NIV stage, with triacylglycerol comprising up to 26% of their dry weight (DW). During their rapid development from stages CI to CIV, much smaller quantities (

Paleobiological approaches reveal the long-term (Myr) survival of Antarctic terrestrial, marine and freshwater fauna in glacial refugia, which provides constraints for models of past ice sheet extent.

Mixing in Ellis Fjord, Vestfold Hills, East Antarctica, is controlled by processes which are influenced by the extent of ice formation. A study of water temperature and salinity at a site near the middle of the fjord was undertaken from May 1994 to February 1995 after a summer (1993–94) in which the ice cover of the fjord was largely retained. Vertical mixing resulting from the exclusion of salt during the limited winter formation of ice was insufficient to mix completely the non-meromictic basins of the fjord. In contrast, a previous study during a winter with far more ice production recorded much stronger vertical mixing throughout the fjord. Warming and freshening of the fjord during the 1994–95 summer, when the ice again did not melt significantly, was attributable to the flow of warmer, less saline water along the fjord. This process was probably related to the formation of tidal jets at the narrow and shallow entrance to the fjord, and was thus influenced by the ice conditions around the entrance. These jets would also have introduced significant amounts of extra-fjord water (along with any resident biota) into the fjord.

The annual cycle of dissolved nutrients and the fugacity of CO2 (fCO2), calculated from the concentration of dissolved inorganic carbon (DIC) and pH, was studied over a 14-month long period (December 1993 to February 1995) at a site in Prydz Bay near Davis Station, Vestfold Hills, East Antarctica. Significant spring decreases in fCO2 began under the sea-ice in mid-October, when both water column and sea-ice algal activity resulted in the removal of nutrients and DIC and increased pH. Minimum fCO2 (

The major influences on the salinity and water level of an Antarctic lake are parameterized and a palaeohydrological model linking the palaeosalinity of an Antarctic lake to the palaeohydrology of the lake is developed. Climatic change in this lake is recorded in the evaporative loss trend reconstructed from water level and lakewater salinity estimates. A decrease in salinity betweeñ700 and 200 years BP corresponds with c. 5 m increase in water level over the same time period. Both water level and lakewater salinity then stabilize in the last ~200 years BP. The palaeohydrological model derived from the changes inferred in salinity and water level shows that there is no significant change in evaporation for the last ~700 years but that a lower evaporation period is evident at ~150–200 years BP suggestive of a mild ‘Little Ice Age’ event in the Vestfold Hills.

Thirty-four permanently stratified water bodies were identified in a survey of the Vestfold Hills. Of these, 21 were lakes, six were seasonally isolated marine basins (SIMBs), and seven were marine basins with year round connection to the open ocean. The basins varied markedly in salinity (4 g l−1 to 235 g l−1), temperature (−14°C to 24°C), depth (5 m to 110 m), area (3.6 ha to 146 ha) and surface level (−30 m to 29 m above sea level). The stratification in all the basins was maintained by increases in salinity. During winter, a thermohaline convection cell was present in all lakes and SIMBs directly beneath the ice cover. These cells were the result of brine exclusion from the forming ice, and increased in density throughout winter, penetrating progressively deeper into the lake. Minimum stability, and therefore the maximum likelihood of turnover, occurred at the time of maximum ice formation in spring. At the end of the period of ice formation, the convection cell broke down, and stratification of the surface water occurred. When the ice melted completely, lenses of relatively fresh water capped the lakes, which reduced the effect of wind mixing. Net meltwater input increased the stability of the meromictic basins, while periods of lower water level resulted in deeper penetration of the thermohaline convection cell, increasing the possibility of turnover and destratification.

Modern and Pleistocene polar carbonates occur in East Antarctica in shelf, coast, lakes and marginal to underneath glaciers, associated mainly with glacigene muds, boulder tills and diamictites. Shelf carbonates (in Prydz Bay) are calcitic and unlithified, and consist mainly of sponges, bryozoans, echinoderms, bivalves and diatoms. Coastal carbonates (in the Vestfold Hills) are calcitic and contain faunal assemblages similar to those on the shelf, with calcareous algae, microbial mats, minor peloids and cements. Lake carbonates are aragonitic micrites and peloids. Carbonates close to glaciers (the Loken Moraines) are aragonitic and contain abundant ooids with intragranular fibrous cements. Subglacial carbonates are aragonitic micrites and peloids. Carbonate mineralogy changes from mainly low-Mg calcite in marine shelf to aragonite in brackish to freshwater dominated inland regions.