<div>The Abbot Point to Hydrographers Passage bathymetry survey was acquired for the Australian Hydrographic Office (AHO) onboard the RV Escape during the period 6 Oct 2020 – 16 Mar 2021. This was a contracted survey conducted for the Australian Hydrographic Office by iXblue Pty Ltd as part of the Hydroscheme Industry Partnership Program. The survey area encompases a section of Two-Way Route from Abbot Point through Hydrographers Passage QLD. Bathymetry data was acquired using a Kongsberg EM 2040, and processed using QPS QINSy. The dataset was then exported as a 30m resolution, 32 bit floating point GeoTIFF grid of the survey area.</div><div>This dataset is not to be used for navigational purposes.</div>

The Carnarvon shelf at Point Cloates, Western Australia, is characterised by a series of prominent ridges and hundreds of mounds that provide hardground habitat for coral and sponge gardens. The largest ridge is 20 m high, extends 15 km alongshore in 60 m water depth and is interpreted as a drowned fringing reef. To landward, smaller ridges up to 1.5 km long and 16 m high are aligned to the north-northeast and are interpreted as relict aeolian dunes. Mounds are less than 5 m high and may also have a sub-aerial origin. In contrast, the surrounding seafloor is sandy with relatively low densities of epibenthic organisms. The dune ridges are estimated to be Late Pleistocene in age and their preservation is attributed to cementation of calcareous sands to form aeolianite, prior to the postglacial marine transgression. On the outer shelf, sponges grow on isolated low profile ridges at ~85 m and 105 m depth and are also interpreted as partially preserved relict shorelines.

Abstract: The Collaborative East Antarctic Marine Census (CEAMARC) surveys to the Terre Adélie and George V shelf and margin highlight the requirement for a revised high resolution depth model that can be used as a spatial tool for improving physical models of the region. We have combined available shiptrack and multibeam bathymetry, coastline and land topographic data to develop a new high-resolution depth model, called GVdem. GVdem spans an area 138°E to 148°E longitude and 63°S to 69°S latitude, with a choice of three ESRI grids with cell pixel sizes: 15 arcsec, 9 arcsec and 3.6 arcsec. The revised depth model is an improvement over previously available regional-scale grids, and highlights seabed physiographic detail not previously observed for this part of East Antarctica. In particular, the extent and complexity of the inner-shelf depressions are revealed and their relationship with large shelf basins and adjacent flat-topped banks.

Short contribution to "Atlas of Submarine Glacial Landforms"

The new acquisition of multibeam bathymetry data along with potential field, seismic data and sediment and rock samples has provided a large quantity of new data in the Northern Lord Howe Rise. A detailed study of the relationships between the surface and sub-surface features over the Capel and Faust basins suggests that seafloor deformation is linked to the underlying basement architecture. Numerous seafloor and sub-surface geological features have been identified and mapped over the study area. Their nature, distribution and relationships have been analysed to propose their formative mechanisms. Most of these features are related to buried igneous intrusions and fluid flow either located within depocentre megasequences or along basement bounding faults. The co-genetic geological features indicate that fluid flow is mainly driven by igneous activity. The ongoing fluid flows, after each magmatic pulse has re-utilised pre-existing fluid conduits. Major depocentres have been identified over the study area and could be prospective for petroleum exploration. Potential source, reservoir and seal rocks are likely to be present in the capel and Faust basins. Volcanic activity has driven the geology and fluid flow over the study area since at least the Upper Cretaceous and has to be considered when assessing the petroleum prospectivity of the Capel and Faust basins and also elsewhere in the Lord Howe Rise.

Lord Howe Rise is a deep sea marginal plateau located in the Coral Sea and Tasman Sea, ~125,000 km2 in area and 750 to 1200 m in water depth. An area of the western flank of northern Lord Howe Rise covering ~25,500 km2 was mapped and sampled by Geoscience Australia in 2007 to characterise the deep sea environments and benthic habitats. Geomorphic features in the survey area include ridges, valleys, plateaus and basins. Smaller superimposed features include peaks, moats, holes, polygonal furrows, scarps and aprons. The physical structure and biological composition of the seabed was characterised using towed video and sampling of epifaunal and infaunal organisms. These deep sea environments are dominated by thick depositional soft-sediments (sandy mud), with local outcrops of volcanic rock and mixed gravel-boulders. Ridge, valley and plateau environments were moderately bioturbated but few organisms were directly observed or collected. Volcanic peaks were bathymetrically complex hard-rock structures that supported sparse distributions of suspensions feeders (e.g. cold water corals and glass sponges) and associated epifauna (e.g. crinoids and brittlestars). Isolated outcrops along the sloping edge of one ridge also supported similar assemblages, some with high localised densities of coral-dominated assemblages.

A bathymetric survey of Darwin Harbour was undertaken during the period 24 June to 20 August 2011 by iXSurvey Australia Pty Ltd for the Department of Natural Resources, Environment, The Arts and Sport (NRETAS) in collaboration with Geoscience Australia (GA), the Darwin Port Corporation (DPC) and the Australian Institute of Marine Science (AIMS) using GA's Kongsberg EM3002D multibeam sonar system and DPC's vessel Matthew Flinders.

ArcGIS shapefile detailing GA's multibeam bathymetry holdings and coverage.

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.

Please note: This product has been superseded by 50m Multibeam Dataset of Australia 2018. - This tile contains all multibeam data held by Geoscience Australia on February 2012 within the specified area. The data has been gridded to 50m resolution. Some deeper data has also been interpolated within the mapped area. The image provided can be viewed on the free software CARIS Easyview, available from the CARIS website: www.caris.com under Free Downloads.