The shallow-water (<160m) marine environment around the Australian research station, Casey station (east Antarctica) is a high use area, frequently visited by both large resupply vessels and smaller workboats conducting scientific research in the area, yet high resolution modern bathymetric data in the area, as well as much of the east Antarctic continental margin, is limited. The Casey area hosts significant levels of biodiversity, but this knowledge is geographically restricted in scope (i.e. shallow depths, close to shore). This biodiversity faces pressures from human activities and effects of climate change, yet extensive knowledge gaps remain, limiting efforts to conserve and manage it effectively. Improved bathymetric surveying in this region will begin to fill these knowledge gaps by conducting representative sampling of both the physical environment and biological communities and reduce the risk to maritime operations in the region. During the period December 2014 to February 2015, a collaborative multibeam survey (Australian Antarctic Division, Royal Australian Navy and Geoscience Australia) was conducted in the shallow-water near-shore regions adjacent to Casey station and covered an area of ca. 28 km2. The survey employed Geoscience Australia's KONGSBERG EM3002 dual head sonar system mounted on an Australian Antarctic Division supplied science workboat, the RV Howard Burton. In total, the surveyed region covered ca. 34 km2, to a maximum depth of ca. 170m. The data was processed in CARIS v8 and a seafloor surface has been gridded at a resolution of 1m. Preliminary field-based interpretation of the submarine geomorphology reveal several dominant geomorphological features which can be simplified into 4 domains as follows: (1) NW and WSW trending fault and channel systems, (2) glacio-fluvial seafloor features (possible terminal moraines) within channel features, (3) bedrock basement highs and (4) `deep isolated basins.

As part of Geoscience Australia's commitment towards the National Environmental Programme's Marine Biodiversity Hub, we have developed a fully four-dimensional (3D x time) Lagrangian biophysical dispersal model to simulate the movement of marine larvae over large, topographically complex areas. The model operates by fusing the results of data-assimilative oceanographic models (e.g. BLUELink, HYCOM, ROMS) with individual-based particle behaviour. The model uses parallel processing on Australia's national supercomputer to handle large numbers of simulated larvae (on the order of several billion), and saves positional information as points within a relational database management system (RDBMS). The model was used to study Australia's northwest marine region, with specific attention given to connectivity patterns among Australia's north-western Commonwealth Marine Reserves and Key Ecological Features (KEFs). These KEFs include carbonate terraces, banks and reefs on the shelf that support diverse benthic assemblages of sponges and corals, and canyons that extend from the shelf edge to the continental slope and are potential biodiversity hotspots. We will show animations of larval movement near canyons within the Gascoyne CMR; larval dispersal probability clouds partitioned by depth and time; as well as matrices of connectivity values among features of interest. We demonstrate how the data can be used to identify connectivity corridors in marine environments, and how the matrices can be analysed to identify key connections within the network. Information from the model can be used to inform priorities for monitoring the performance of reserves through examining net contributions of different reserves (i.e. are they sources or sinks), and studying changes in connectivity structure through adding and removing reserve areas.

<p>This resource contains surface sediment data for Outer Darwin Harbour collected by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Northern Territory Government (Department of Land Resource Management) during the period from 28 May and 23 June 2015 on the RV Solander (survey SOL6187/GA0351). This project was made possible through offset funds provided by INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The intent of this four year (2014-2018) program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps that underpin marine resource management decisions. The specific objectives of the survey were to: <p>1. Obtain high resolution geophysical (bathymetry) data for outer Darwin Harbour, including Shoal Bay; <p>2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for outer Darwin Harbour, including Shoal Bay; and <p>3. Collect tidal data for the survey area. <p>Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; physical samples of seabed sediments, underwater photography and video of grab sample locations and oceanographic information including tidal data and sound velocity profiles. <p>A detailed account of the survey is provided in: <p>Siwabessy, P.J.W., Smit, N., Atkinson, I., Dando, N., Harries, S., Howard, F.J.F., Li, J., Nicholas, W.A., Potter, A., Radke, L.C., Tran, M., Williams, D. and Whiteway, T., 2015. Outer Darwin Harbour Marine Survey 2015: GA0351/SOL6187 Post-survey report. Record 2016/008. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2016.008

The Australian Government, through Geoscience Australia, is tailoring its national seabed mapping program to support the implementation of policies aimed at delivering improved clean energy options for the nation. The current focus is upon the assessment of offshore sedimentary basins as potential sites for the geological storage of carbon dioxide (CO2). These assessments include targeted seabed research that aims to reduce uncertainty around the risks of CO2 storage by developing an integrated understanding of the physical connectivity between the deeper basin structures, the shallow (<100 m) sub-surface and seabed environments. This paper presents an overview of the science strategy developed to undertake this work in the Australian context, with reference to case studies.

The grid was created from the Australian bathymetry and topography grid (2009, version 4). The data represents the degree of slope of an area of seabed (a rectangle of 3 by 3 cells).

This resource contains surface sediment data for Outer Darwin Harbour collected by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Northern Territory Government (Department of Land Resource Management) during the period from 28 May and 23 June 2015 on the RV Solander (survey SOL6187/GA0351). This project was made possible through offset funds provided by INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The intent of this four year (2014-2018) program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps that underpin marine resource management decisions. The specific objectives of the survey were to: 1. Obtain high resolution geophysical (bathymetry) data for outer Darwin Harbour, including Shoal Bay; 2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for outer Darwin Harbour, including Shoal Bay; and 3. Collect tidal data for the survey area. Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; physical samples of seabed sediments, underwater photography and video of grab sample locations and oceanographic information including tidal data and sound velocity profiles. A detailed account of the survey is provided in: Siwabessy, P.J.W., Smit, N., Atkinson, I., Dando, N., Harries, S., Howard, F.J.F., Li, J., Nicholas, W.A., Potter, A., Radke, L.C., Tran, M., Williams, D. and Whiteway, T., 2015. Outer Darwin Harbour Marine Survey 2015: GA0351/SOL6187 Post-survey report. Record 2016/008. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2016.008

The dominant ocean current off the Western Australian (WA) coast is the Leeuwin Current (LC) [1]. It is a warm, poleward flowing surface current up to 300 metres in depth and exhibits significant seasonal differences in intensity, ranging from strong during the austral winter and weak during the austral summer [2-3]. At a regional scale, the LC is significant because it directly influences the temperature and nutrient dynamics of the WA ocean ecosystem [3]. As a result, it has been shown that the LC affects the production of phytoplankton [4-5], the recruitment of western rock lobster [6], and the distribution of fishes and algae [7]. The LC can be observed from Sea Surface Temperature (SST) satellite-derived images. However, delineating an accurate map showing the extent and spatial structure of the LC from a SST image remains a challenge. And given the large area covered by the LC, an automatic approach is desirable. This study aims to test an object-based image processing technique from time-series MODIS SST data for the above purpose. SeaDas image processing software was used to process MODIS images from daily raw data to Level 3 products. The monthly SST4 layers between June 2009 and May 2010 were the inputs for this study. The SST layer shown in Figure 1a clearly indicates a warmer (than off-shore) southward flowing current (LC) that extends from Exmouth, passing Cape Leeuwin, into the Great Australian Bight. Previously, relative temperature differences have been employed to identify LC structure from SST images [8]. An off-shore SST profile crossing the LC (Figures 1a & b) shows that the LC, indicated by warmer temperatures, occupies a zone approximately between 10 km and 90 km from the coast, with a core current between 35 km and 70 km. This study utilised two characteristics of MODIS-derived sea surface temperatures to identify the extents of the LC. The first characteristic is that the LC is warmer than surrounding waters. The second characteristic is the connectivity between the core LC current and the eddies. According to the first characteristic, the SST images were treated as elevation surfaces where the LC occupies slope and ridge positions. Topographic Position Index (TPI) was then derived from these SST layers to identify topographic positions [9]. As shown in Figure 1c, the LC approximately corresponds with areas of large positive TPI values. In the next step, the multi-resolution algorithm in eCognition Developer was employed to segment the SST and TPI layers of each month into objects. The objects were classified into a pseudo LC class if their mean TPI values are greater than 0.25 of the global standard deviation value. The second characteristic of the LC was then used to remove false positive objects. To do that, a small number of objects at known LC locations were selected as 'seeds'. In a looping process, any objects that connect with these seeds were classified as true LC class. The extents of the LC for the 12 months analysed here areshown in Figure 2. The LC during austral winter is clearly stronger (e.g., larger in extent) than during austral summer, which confirms the findings of other studies [2-3]. The LC during the summer time is patchier, which required more seeds (8-14) than during the winter time (less than 5 seeds). The core summer current is also slightly further away from the coast. In addition, eddies are clearly visible in most months. In summary, the proposed object-based approach was semi-automatic and effective in delineating the extents of the LC although there is a degree of subjectivity in the selection of accurate seeds. The weak summer current, however poses some difficulty for the approach and future work is aimed at improving the modelling accuracy.

Geoscience Australia marine reconnaissance survey TAN0713 to the Lord Howe Rise offshore eastern Australia was completed as part of the Federal Government's Offshore Energy Security Program between 7 October and 22 November 2007 using the New Zealand Government's research vessel Tangaroa. The survey was designed to sample key, deep-sea environments on the east Australian margin (a relatively poorly-studied shelf region in terms of sedimentology and benthic habitats) to better define the Capel and Faust basins, which are two major sedimentary basins beneath the Lord Howe Rise. Samples recovered on the survey contribute to a better understanding of the geology of the basins and assist with an appraisal of their petroleum potential. They also add to the inventory of baseline data on deep-sea sediments in Australia. The principal scientific objectives of the survey were to: (1) characterise the physical properties of the seabed associated with the Capel and Faust basins and Gifford Guyot; (2) investigate the geological history of the Capel and Faust basins from a geophysical and geological perspective; and (3) characterise the abiotic and biotic relationships on an offshore submerged plateau, a seamount, and locations where fluid escape features were evident. This dataset comprises organic carbon and nitrogen concentrations and isotopes in the upper 2 cm of seabed sediments. Some relevant publications which pertain to these datasets include: 1. Heap, A.D., Hughes, M., Anderson, T., Nichol, S., Hashimoto, T., Daniell, J., Przeslawski, R., Payne, D., Radke, L., and Shipboard Party, (2009). Seabed Environments and Subsurface Geology of the Capel and Faust basins and Gifford Guyot, Eastern Australia - post survey report. Geoscience Australia, Record 2009/22, 166pp. 2. Radke, L.C. Heap, A.D., Douglas, G., Nichol, S., Trafford, J., Li, J., and Przeslawski, R. 2011. A geochemical characterization of deep-sea floor sediments of the northern Lord Howe Rise. Deep Sea Research II 58: 909-921

In September and October of 2011 Geoscience Australia surveyed part of the offshore northern Perth Basin in order to map potential sites of natural hydrocarbon seepage. The primary objectives of the survey were to map the spatial distribution of seepage sites and characterise the nature of the seepage at these sites (gas vs oil, macroseepage vs microseepage; palaeo vs modern day seepage) on the basis of: acoustic signatures in the water column, shallow subsurface and on the seabed; geochemical signatures in rock and sediment samples and the water column; and biological signatures on the seabed. Areas of potential natural hydrocarbon seepage that were surveyed included proven (drilled) oil and gas accumulations, a breached structure, undrilled hydrocarbon prospects, and areas with potential signatures of fluid seepage identified in seismic, satellite remote sensing and multibeam bathymetry data. Within each of these areas the survey acquired: water column measurements with the CTD; acoustic data with single- and multi-beam echosounders, sidescan sonar and sub-bottom profiler (sidescan not acquired in Area F as it was too deep in places); and sediment and biological samples with the Smith-McIntyre Grab. In addition, data were collected with a remotely operated vehicle (ROV), integrated hydrocarbon sensor array, and CO2 sensor in selected areas. Sampling with the gravity corer had limited success in many of the more shallow areas (A-E) due to the coarse sandy nature of the seabed sediments. This dataset comprises mineraology of the upper 2cm of seabed sediment. The mineral assemblage includes quartz, aragonite, calcite and high-Mg calcite expressed as mol %.

Geoscience Australia undertook a marine survey of the Vlaming Sub-basin in March and April 2012 to provide seabed and shallow geological information to support an assessment of the CO2 storage potential of this sedimentary basin. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The Vlaming Sub-basin is located offshore from Perth, Western Australia, and was previously identified by the Carbon Storage Taskforce (2009) as potentially highly suitable for CO2 storage. The principal aim of the Vlaming Sub-basin marine survey (GA survey number GA334) was to look for evidence of any past or current gas or fluid seepage at the seabed, and to determine whether these features are related to structures (e.g. faults) in the Vlaming Sub-basin that may extend up to the seabed. The survey also mapped seabed habitats and biota in the areas of interest to provide information on communities and biophysical features that may be associated with seepage. This research addresses key questions on the potential for containment of CO2 in the Early Cretaceous Gage Sandstone (the basin's proposed CO2 storage unit) and the regional integrity of the South Perth Shale (the seal unit that overlies the Gage Sandstone). This dataset comprises chlorophyll a, b and c from seabed sediments (0-0.5cm).