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.

In 2010, a network of Marine Protected Areas (MPAs) was proposed for the East Antarctic region. This proposal was based on the best available data, which for the benthic regime consisted chiefly of seabed geomorphology and satellite bathymetry data. Case studies from the East Antarctic region indicate that depth and morphology are important factors in delineating marine benthic communities, particularly on the continental shelf. However, parameters such as sediment composition also show a strong association with the distribution and diversity of benthic assemblages. A better assessment of the nature of benthic habitats within the proposed MPA network is now possible with the incorporation of a compilation of sediment properties and higher resolution bathymetry grids across the East Antarctic region (see Figures A and B). Based on these physical properties, and in combination with the seabed morphology, we can now distinguish a range of distinct habitats, such as deep muddy basins, scoured sandy shelf banks, ruggedly eroded slope canyons and muddy deep sea plains. In this presentation, we assess the types of benthic habitats across the East Antarctic region, and then determine how well the proposed MPA network represents the diversity of habitats across this margin. The diversity of physical environments within the proposed MPAs suggests that they likely support a diverse range of benthic communities which are broadly representative of the surrounding region.

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.

<p>Geoscience Australia, the Royal Australian Navy (RAN) and the Australian Antarctic Division (AAD) conducted a hydrographic surveying and seafloor characterisation survey in nearshore waters offshore from Davis Station in the Australian Antarctic Territory. <p>The multibeam data was acquired during January-February 2017 using two workboats. Geoscience Australia used the AAD workboat Howard Burton and the Royal Australian Navy used their Antarctic Survey Vessel (ASV) Wyatt Earp. The survey is a component of Australian Antarctic Program (AAP) Project 5093 Hydrographic Surveying and Seafloor Characterisation Program (Chief Investigator: Ursula Harris, AAD). <p>The objective of the survey was to map the seabed environment in shallow (<300 m) coastal waters adjacent to Davis station in the Vestfold Hills region, to obtain data for the compilation of nautical charts and to acquire fundamental baseline data necessary for informed environmental management, science, infrastructure and logistical operations. <p>Data collected during the survey includes high-resolution multibeam bathymetry and backscatter data, sediment samples, seafloor imagery and sub-bottom profiles. <p>This dataset comprises a backscatter grid from multibeam sonar data acquired using the AAD workboat Howard Burton, gridded at 2 m spatial resolution, covering a combined area of 90 km2. The Chief Scientist onboard the Howard Burton was Dr. Jodie Smith (Geoscience Australia).

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.'

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 modelling of water movement around Davis, and to update and extend the navigational charts of the region.

Short contribution to "Atlas of Submarine Glacial Landforms"

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

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.

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 environmental change across the nearshore marine environment. 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.