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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 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.

Antarctic benthic ecosystems support high biodiversity but their characterization is limited to a few well-studied areas, due to the extreme environment and remoteness making access and sampling difficult. Our aim was to compare water and sediment as sources of environmental DNA (eDNA) to better characterise Antarctic benthic communities and further develop practical approaches for DNA-based biodiversity assessment in remote environments. We used a cytochrome c oxidase subunit I (COI) metabarcoding approach to characterise metazoan communities in 26 nearshore sites across 12 locations in the Vestfold Hills (East Antarctica) based on DNA extracted from either sediment cores or filtered seawater. We detected a total of 99 metazoan species from 12 phyla across 26 sites, with similar numbers of species detected in sediment and water eDNA samples. However, significantly different communities were detected in the two sample types at sites where both were collected (i.e., where paired samples were available). For example, nematodes and echinoderms were more likely to be detected exclusively in sediment and water eDNA samples, respectively. eDNA from water and sediment core samples are complementary sample types, with epifauna more likely to be detected in water column samples and infauna in sediment. More reference DNA sequences are needed for infauna/meiofauna to increase the proportion of sequences and number of taxa that can be identified. Developing a better understanding of the temporal and spatial dynamics of eDNA at low temperatures would also aid interpretation of eDNA signals from polar environments. Our results provide a preliminary scan of benthic metazoan communities in the Vestfold Hills, with additional markers required to provide a comprehensive biodiversity survey. However, our study demonstrates the choice of sample type for eDNA studies of benthic ecosystems (sediment, water or both) needs to be carefully considered in light of the research or monitoring question of interest.

A 47 cm long sediment core collected from an inland lake of the Vestfold Hills, East Antarctica has been examined to reconstruct the palaeolacustrine environmental changes. The core shows dates at two core intervals of 18-19 cm and 28-29 cm as 5050±98 yrs BP and 5560±96 yrs BP, respectively. The core exhibits a good amount of diatom population throughout the length. Prior to 5560±96 yrs BP, the core shows high abundance of diatom population (>10×10 7 g –1 ) along with sufficient salt crystal, which indicates the connection of this lake with the marine environment. From 5560±96 yrs BP to 5050±98 yrs BP the total number diatoms decreased substantially along with the decrease in salt crystal, which indicates the withdrawal of the marine influence from the lake during that period. From 5050±98 yrs BP to Recent, the low number of diatoms and the rare occurrence of salt crystal suggest that the lake remained mostly detached from the sea during the last 5000 yrs. Key words: Vestfold Hills, lake sediment core, diatom, salt crystal, connection with sea

Prydz Bay is one of the largest embayments on the East Antarctic coast and it is the discharge point for approximately 16% of the East Antarctic Ice Sheet. Geological constraints on the regional ice sheet history include evidence of past relative sea-level change at three sites; the Vestfold Hills, Rauer Islands and Larsemann Hills. In this paper we compile updated regional relative sea-level data from these sites. We compare these with a suite of relative sea-level predictions derived from glacial isostatic adjustment models and discuss the significance of departures between the models and the field evidence. The compiled geological data extend the relative sea-level curve for this region to 11,258 cal yr BP and include new constraints based on abandoned penguin colonies, new isolation basin data in the Vestfold Hills, validation of a submarine relative sea-level constraint in the Rauer Islands and recalibrated radiocarbon ages at all sites dating from 12,728 cal yr BP. The field data show rapid increases in rates of relative sea level rise of 12-48 mm/yr between 10,473 (or 9678) and 9411 cal yr BP in the Vestfold Hills and of 8.8 mm/yr between 8882 and 8563 cal yr BP in the Larsemann Hills. The relative sea-level high stands of >= 8.8 m from 9411 to after 7564 cal yr BP (Vestfold Hills) and >= 8 mat 8563 and 7066 cal yr BP (Larsemann Hills) are over-predicted by some of the glacial isostatic adjustment models considered here, suggesting that assumptions relating to the magnitude and timing of regional ice loss since the Last Glacial Maximum may need revising. In the Vestfold Hills and Rauer Islands the final deglacial sea-level rise was almost exactly cancelled out by local rebound between 9411 and 5967 cal yr BP and this was followed by a near exponential decay in relative sea-level. In the Larsemann Hills the sea-level data suggest that the rate of ice retreat in this region was not uniform throughout the Holocene. Swath bathymetric surveys of the benthic seafloor topography show the presence of multiple offshore basins. These are a priority for further study as those that remained free of grounded ice should provide precise constraints on relative sea-level rise and ice sheet history during the most rapid phases of the last major deglaciation.