Surveying of nearshore areas in the Vestfold Hills using high resolution multibeam swath bathymetry provides both a detailed digital bathymetric model and information on sediment acoustic backscatter. Combined with underwater video transects and sediment sampling, these data can be used to identify and map geomorphic units. Six geomorphic units identified in the survey region include: Rocky outcrops, sediment-floored basins, pediments, steep-sided valleys, scarps and sheltered embayments. In addition to geomorphic units, the data reveal sedimentary structures that provide insights into sediment transport and erosion in the area. Ice keel pits and scours are common while seafloor channels, scour depressions and sand ribbons indicate transport and deposition by wind-driven currents and oceanographic circulation. Gullies and sediment lobes on steep slopes indicate mass movement of sediment. The sheltered embayments preserve a mantle of boulder sand probably deposited by cold-based glaciers. Automated techniques utilizing the bathymetric grid and backscatter to map landforms are useful in defining reproducible boundaries between geomorphic units but cannot easily be adapted to accurately classify the variations in sea floor texture and structure imaged by these data.

Short contribution to "Atlas of Submarine Glacial Landforms"

The value of integrated high-resolution data sets in understanding the marine environment has been demonstrated in numerous studies around the Australian margin, however this approach has rarely been applied to studies in East Antarctica. This integrated approach was applied to a survey in Antarctica which utilised a multibeam sonar system, underwater video and sediment sampling to aid the understanding of seabed character and benthic biotopes in the coastal waters of the Vestfold Hills, near the Australian station of Davis. The Vestfold Hills is one of the largest ice-free areas on the East Antarctic coast. The coastal area is a complex of small islands, embayments and fjords. High-resolution bathymetry and backscatter data were collected over 42km2 to depths of 215 m. Epibenthic community data and in situ observations of seafloor morphology, substrate composition and bedforms were obtained from towed underwater video. The new high resolution datasets reveal a mosaic of rocky outcrops and sediment-filled basins. Analysis of the datasets was used to identify statistically distinct benthic assemblages and describe the physical habitat characteristics related to each assemblage, with seven discrete benthic biotopes identified. The biotopes include a range of habitat types including shallow coastal embayments and rocky outcrops, which are dominated by dense macroalgae communities, and deep muddy basins which are dominated by mixed invertebrate communities. Transition zones comprising steep slopes provide habitat for sessile invertebrate communities. Flat to gently sloping plains with a thin sandy cover on shallow bedrock are relatively barren. The relationship between benthic community composition and environmental parameters is complex with many variables (e.g. depth, substrate type, longitude, latitude and slope) contributing to differences in community composition. Depth and substrate type were identified as the main controls of benthic community composition, however, depth is likely a proxy for other unmeasured depth-dependent parameters such as light availability, frequency of disturbance by ice, currents and/or food availability. Sea ice cover is an important driver of benthic community composition, with dense macroalgae communities only found where ice-free conditions persist for most of the summer. The bathymetry data shows iceberg scouring is common, however, scouring does not appear to impact benthic community composition in the study area. This is the first study that has used an integrated sampling approach to investigate benthic assemblages across a range of habitats in a coastal marine environment in East Antarctica. This study demonstrates the efficacy of using multibeam and towed video systems to survey large areas of the seafloor in Antarctica where marine sampling is often logistically difficult, and to collect non-destructive high-resolution data in the sensitive Antarctic marine environment. The multibeam data provide a physical framework for understanding benthic habitats and the distribution of benthic communities. This research provides a baseline for assessing natural variability and human-induced change across the coastal marine environment (Australian Antarctic Science Project AAS-2201), contributes to Geoscience Australia's Marine Environmental Baseline Program, and supports Australian Government objectives to manage and protect the Antarctic marine environment.

An integrated analysis of geoscience information and benthos data has been used to identify benthic biotopes (seafloor habitats and associated communities) in the nearshore marine environment of the Vestfold Hills, East Antarctica. High-resolution bathymetry and backscatter data were collected over 42km2 to depths of 215 m using a multibeam sonar system. Epibenthic community data and in situ observations of seafloor morphology, substrate composition and bedforms were obtained from towed underwater video. Analysis of the datasets was used to identify statistically distinct benthic assemblages and describe the physical habitat characteristics related to each assemblage, with seven discrete biotopes identified. The biotopes include a range of habitat types including shallow coastal embayments and rocky outcrops which are dominated by dense macroalgae communities, and deep muddy basins which are dominated by mixed invertebrate communities. Transition zones comprising steep slopes provide habitat for sessile invertebrate communities. Areas of flat sandy plains are relatively barren. The relationship between benthic community composition and environmental parameters is complex with many variables (e.g. depth, substrate type, longitude, latitude and slope) contributing to differences in community composition. Depth and substrate type were identified as the main drivers of benthic community composition, however, depth is likely a proxy for other unmeasured depth-dependent parameters such as light availability, frequency of disturbance by ice, currents and/or food availability. Sea ice cover is also an important driver and the benthic community in areas of extended sea ice cover is comprised of sessile invertebrates and devoid of macroalgae. This is the first study that has used an integrated sampling approach based on multibeam sonar and towed underwater video to investigate benthic assemblages across a range of habitats in a nearshore marine environment in East Antarctica. This study demonstrates the efficacy of using multibeam sonar and towed video systems to survey large areas of the seafloor and to collect non-destructive high-resolution data in the sensitive Antarctic marine environment. The multibeam data provide a physical framework for understanding benthic habitats and the distribution of benthic communities. This research provides a baseline for assessing natural variability and human induced change on nearshore marine benthic communities (Australian Antarctic Science Project AAS-2201), contributes to Geoscience Australia's Marine Environmental Baseline Program, and supports Australian Government objectives to manage and protect the Antarctic marine environment.

Numerical models are the primary predictive tools for understanding the dynamic behavior of the Antarctic ice sheet. But a key boundary parameter - the magnitude of sub-glacial heat flow - is controlled by geological factors and remains poorly constrained. We show that variations in the abundance and distribution of heat producing elements (U, Th and K) within the Antarctic continental crust give rise to regional sub-glacial heat flows as much as 2-3 times greater than previously assumed in ice modeling studies. We also recognize that, prior to the breakup of Gondwana, much of the East Antarctic continental crust was contiguous with southern Australia where extensive high-heat producing Proterozoic-aged rocks, and correspondingly elevated regional heat flows, are well documented. Such crustal rocks almost certainly extend beneath the modern east Antarctic ice sheet. This means that high sub-glacial heat flows are likely to be a regional phenomenon. Such fundamental geological controls on sub-glacial heat flow must be considered in accurately modelling ice dynamics, permitting more refined predictions of ice mass balance and sea level change.

Incorporating the distribution of 'hot rocks' in East Antarctica into ice sheet models, will improve predictions of ice sheet behaviour and potential sea-level change, according to new Australian research. Speaking at the 'Strategic Science in Antarctica' conference in June, Dr Chris Carson from Geoscience Australia, said naturally occurring 'heat-producing elements' - mainly uranium, thorium and potassium - present in certain rock types found in Antarctica, contribute to local and regional-scale variation in heat flow underneath the ice sheet. They do this by generating tiny amounts of heat by radioactive decay. 'These regions of elevated heat flow potentially can contribute to ice surging and ice stream flow,' Dr Carson said. Sub-glacial heat flow under the West Antarctic ice sheet has been measured at a number of sites and found to be elevated due to active rifting and volcanism. However, crustal heat flow beneath the East Antarctic ice sheet is poorly understood, and instead, a broadly uniform heat flow across much of the region is often assumed in ice sheet models. Such assumptions ignore the natural variability of heat flow due to variations in the sub-glacial geology. To illustrate the scale and importance of this variability, Dr Carson and colleagues from the Australian Antarctic Division, Antarctic Climate and Ecosystems Cooperative Research Centre, University of Melbourne and the University of Texas, recently published a paper in the Journal of the Geological Society, London, describing the distribution of hot rocks, and their impact on regional heat flow, in different parts of the Australian Antarctic Territory. In a 275 km transect along the Prydz Bay coastline - running from the Vestfold Hills to the Amery Ice Shelf - heat production values for individual rock types (derived from geochemical analysis of the rocks) ranged from 0.02 µW per cubic metre to almost 66 µW per cubic metre (1 µW [micro Watt] is 0.000001 Watts). 'There is generally low and reasonably typical heat production in rocks of the northern Prydz Bay region - in the Vestfold Hills and Rauer Group,' Dr Carson said. 'However, in southern Prydz Bay, there are numerous outcrops of Cambrian-aged granites which are characterised by elevated heat production. The presence of these hot rocks fundamentally affects the regional heat flow in southern Prydz Bay.' Available aeromagnetic data suggests that these hot granites may be more widespread underneath the ice sheet in southern Prydz Bay. Dr Carson said a better knowledge of the sub-glacial location and distribution of such granites across East Antarctica is essential for understanding regional heat flow characteristics of the Antarctic crust. This information can then be factored into ice modelling studies. `The assumption that the crust of East Antarctica is thermally homogenous is inappropriate and it is critical that both local and regional geology are considered in ice modelling studies,- he said. 'As elevated and variable heat flow would have a fundamental effect on ice sheet behaviour, incorporating geological controls on heat flow into models could refine predictions of ice mass balance and sea-level change.'

ESRI Grids of available bathymetry within the bounds of proposed Marine Protected Areas in the Antarctic. Interpolated datasets are also included.

Sediment grainsize and compositional data is presented for the East Antarctic region (30-150ºE) south of 60ºS to provide insight into the nature of habitats available for benthic communities. This compilation of sedimentary properties incorporates data collected and analysed from the 1950s to 2012. Sediment grainsize data is presented from quantitative analyses (472 samples) and Folk classifications (an additional 192 samples), and composition data is presented for calcium carbonate (255 samples) and biogenic silica (304 samples). Sedimentary properties are a key environmental layer for understanding the nature and diversity of benthic habitats. In this report, sediment grainsize and composition data are overlain on maps of bathymetry and geomorphic features, to further illustrate key variations in seabed habitats. The Antarctic shelf is typically dissected by deep troughs and channels, and these form sediment depocenters for fine grained biosiliceous material. Shelf banks, by contrast, are typically composed of coarser sands and gravels due to their exposure to stronger currents and frequent iceberg scouring. The continental slope is heavily eroded into rugged canyons which also contain coarser sediments due to reworking by down slope processes. In several regions, high carbonate content occurs at the shelf break, associated with areas of known hydrocoral occurrence. These variations in physical properties across the Antarctic shelf and slope create distinct habitats for seabed communities. Maps of sediment type, together with broader-scale maps of geomorphic features, can therefore guide understanding of the nature and distribution of seabed habitats in East Antarctica, and particularly within the seven proposed Marine Protected Areas (MPAs) within this region. Sedimentary and geomorphic properties are shown to be highly variable within these MPAs, indicating that these areas likely support a wide variety of benthic communities.

The Davis Coastal Seabed Mapping Survey, Antarctica (GA-4301 / AAS2201 / HI468) was acquired by the Australian Antarctic Division workboat Howard Burton during February-March 2010 as a component of Australian Antarctic Science (AAS) Project 2201 - Natural Variability and Human Induced Change on Antarctic Nearshore Marine Benthic Communities. The survey was undertaken as a collaboration between Geoscience Australia, the Australian Antarctic Division and the Australian Hydrographic Service (Royal Australian Navy). The objectives were to provide multibeam bathymetry and backscatter of the coastal region of the Vestfold Hills around Davis Station, Antarctica, to aid the understanding of sea bed character, benthic habitats, provide a basis for hydrodynamic modeling of water movement around Davis, and to update and extend the navigational charts of the region.

The Casey Station Bathymetry Survey was conducted last summer from December 2014 to February 2015. This collaborative survey was undertaken by Geoscience Australia, the Royal Australian Navy and the Australian Antarctic Division, using the AAD's workboat the RV Howard Burton. The survey goal was to acquire high resolution bathymetry data to improve our understanding of the seafloor using multibeam sonar. The bathymetry data collection will be supplemented by physical sampling of the seafloor sediments and video recordings of the biological communities living in the seafloor. The survey will cover areas that haven't been charted during the 2013 Casey Survey and are frequently used by the RSV Aurora Australis. Improving our understanding of the seabed environment in these shallow coastal waters will ultimately lead to a better environmental management of the Australian Antarctic Territory. The data will also help the RAN to develop more accurate navigation charts therefore reducing the risk to maritime operation in the region.