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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 which Diatoms of the saline lakes of the Vestfold Hills, Antarctica by 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 of Luticola, Sabbea and Halamphora, 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. [ABSTRACT FROM AUTHOR]

Abstract: The Vestfold Hills terrane in East Antarctica is a granulite facies terrane that preserves a record of sedimentation, magmatism and metamorphism that differs significantly from the other Archaean terranes exposed in East Antarctica. Sensitive High Resolution Ion Mass Spectrometry (SHRIMP) U–Pb isotopic data from detrital zircon cores, metamorphic rims and metamorphic zircon and monazite from the granulite facies Chelnok and Taynaya Paragneisses that demonstrate Archaean ages that are incompatible with the established ages of other East Antarctic source regions. The original sediments to the Chelnok and Taynaya Paragneisses were deposited between c. 2575 and c. 2520Ma and underwent a protracted period of high-grade granulite-facies metamorphism from c. 2520 to c. 2450Ma that is synchronous with the emplacement of the tonalitic Mossel Gneiss and the granitic to gabbroic rocks of the Crooked Lake Gneiss Group. The distinctive detrital zircon age populations and the period metamorphism recorded by the Vestfold Hills paragneisses lead us to speculate that: (1) these rocks were sourced from, and deposited on the margin of the crystalline basement to the North China Craton at the end of the Archaean, and (2) they underwent a period of high-grade metamorphism related to orogenesis driven by the collision of the North China Craton with the Archaean nucleus of South India during the late-Archaean to early-Paleoproterozoic. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

The water chemistry of lake systems on the edge of the Antarctic continent responds quickly to changes in the moisture balance. This is expressed as increasing salinity and decreasing lake water level during dry periods, and the opposite during wet periods. The diatom composition of the lakes also changes with these fluctuations in salinity and lake water depth. This is important, as their siliceous remains become incorporated into lake sediments and can provide long-term records of past salinity using transfer functions. In order to develop transfer functions, diatoms and water chemistry data were inter-calibrated from five different East Antarctic oases, namely the Larsemann Hills, the Bølingen Islands, the Vestfold Hills, the Rauer Islands and the Windmill Islands. Results indicate that salinity is the most important environmental variable explaining the variance in the diatom flora in East Antarctic lakes. In oligo- saline lakes the variance is mainly explained by lake water depth. This dataset was used to construct a weighted averaging transfer function for salinity in order to infer historical changes in the moisture balance. This model has a jack-knifed r2 of 0.83 and a RMSEP of 0.31. The disadvantage of this transfer function is that salinity changes in oligo-saline lakes are reconstructed inaccurately due to the ‘edge effect’ and due to the low species turnover along the salinity gradient at its lower end. In order to infer changes in the moisture balance in these lakes, a second transfer function using weighted averaging partial least squares (with two components) for depth was constructed. This model has a jack-knifed r2 of 0.76 and a RMSEP of 0.22. Both transfer functions can be used to infer climate driven changes in the moisture balance in lake sediment cores from oligo-, hypo-, meso- and hyper-saline lakes in East Antarctic oases between 102–75°E. The transfer function for lake water depth is promising to track trends in the moisture balance of small freshwater lakes, where changes in shallow and deep-water sediments are readily reflected in changing diatom composition. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An analysis of diatom assemblages, Total Organic Carbon (TOC), carbon-nitrogen ratio, d 13 C, biogenic silica and carbonate in two marine sediment cores from Ellis Fjord, eastern Antarctica, reveals episodes of climatic change at 3600, 2500, 2000 and 1000 yr BP. Using the diatom data, principal component analysis, the fast-ice index (FI), benthic index (BI) and snow index (SI) (which are derived from the diatom data), a period of reduced temporal sea-ice cover is identified prior to 2500 BP. There was a large increase in sea-ice extent between 2500 and 2000 BP followed by a smaller decline. Temporal sea-ice extent after 2000 BP was still significantly greater than prior to 2500 BP. Both cores were taken from anoxic basins within the fjord. It was found that the better preservation allowed the recognition of taxa such as Chaetoceros vegetative cells, which are not usually preserved. This enabled the distinction between ice-edge blooms, dominated by Fragilariopsis curta, and open-water blooms dominated by Chaetoceros. Even though Watts Basin receives a significant summer meltwater input each year, it has not been possible to recognize this signal in the sediment core. [ABSTRACT FROM AUTHOR]

A high-resolution record of evaporation for the last |650 years was derived from the diatomsalinity signal preserved in a sediment core taken from Ace Lake, Vestfold Hills (68° 289S, 78° 119E), Antarctica. The seasonal oxygen isotope signal preserved in an ice core from Law Dome (66° 449S, 112° 509E), 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. [ABSTRACT FROM AUTHOR]

A comprehensive diatom stratigraphy is used to calculate a palaeosalinity history for an Antarctic lake via an established diatom-salinity transfer function for the Vestfold Hills, Antarctica. A sediment core taken from Ace Lake in 1995 shows three distinct changes in diatom assemblage constituents: initial benthic hyposaline – freshwater taxa are replaced by marine planktonic and sea-ice taxa with these taxa in turn replaced by the benthic hypersaline taxa dominant in the lake today. These changes in assemblage composition enable the lakewater salinity of each stage to be determined, and the Holocene evolution of the lake to be refined. Deglaciation of the Vestfold Hills at the beginning of the Holocene exposed Ace Lake basin; following this, fresh lacustrine diatoms were deposited from | 11 380 to | 8110 corrected 14 C yr BP. Relative sea-level rise after this time led to the progressive marine inundation of the lake and the deposition of marine diatom taxa. Marine taxa were dominant in the sediment for more than 6000 years. Isostatic rebound and stabilization of the sea-level isolated Ace Lake and at | 1480 corrected 14 C yr BP saline lacustrine diatoms became the dominant taxa, indicative of the concentration of dissolved salts through evaporation after isolation. [ABSTRACT FROM AUTHOR]