The Leeuwin Current has significant ecological impact on the coastal and marine ecosystem of south-western Australia. This study investigated the spatial and temporal dynamics of the Leeuwin Current using monthly MODIS SST dataset between July 2002 and December 2012. Topographic Position Index layers were derived from the SST data for the mapping of the spatial structure of the Leeuwin Current. The semi-automatic classification process involves segmentation, 'seeds' growing and manual editing. The mapping results enabled us to quantitatively examine the current's spatial and temporal dynamics in structure, strength, cross-shelf movement and chlorophyll a characteristic. It was found that the Leeuwin Current exhibits complex spatial structure, with a number of meanders, offshoots and eddies developed from the current core along its flowing path. The Leeuwin Current has a clear seasonal cycle. During austral winter, the current locates closer to the coast (near shelf break), becomes stronger in strength and has higher chlorophyll a concentrations. While, during austral summer, the current moves offshore, reduces its strength and chlorophyll a concentrations. The Leeuwin Current also has notable inter-annual variation due to ENSO events. In El Niño years the current is likely to reduce strength, move further inshore and increase its chlorophyll a concentrations. The opposite occurs during the La Niña years. In addition, this study also demonstrated that the Leeuwin Current has a significantly positive influence over the regional nutrient characteristics during the winter and autumn seasons.

The Oceanic Shoals Commonwealth Marine Reserve (CMR) (>71,000 km2) is located in the Timor Sea and is part of the National Representative System of Marine Protected Areas of Australia. The Reserve incorporates extensive areas of carbonate banks and terraces that are recognised in the North and North West Marine Region Management Plans as Key Ecological Features (KEFs). Although poorly studied, these features have been identified as potential biodiversity hotspots for the Australian tropical north. As part of the National Environment Research Program (NERP), Geoscience Australia (GA) in collaboration with the Australian Institute of Marine Sciences (AIMS) undertook a marine biodiversity survey in 2012 to improve the knowledge of this area and better understand the importance of these KEFs. Amongst the many activities undertaken, continuous high-resolution multibeam mapping, video and still camera observations, and physical seabed sampling of four areas covering 510 km2 within the western side of the CMR was completed. Multibeam imagery reveals a high geomorphic diversity in the Oceanic Shoals CMR, with numerous banks and terraces, elevated 30 to 65 m above the generally flat seabed (~105 m water depth), that provide hard substrate for benthic communities. The surrounding plains are characterised by fields of depressions (pockmarks) formed in soft silty sediments that are generally barren of any epibenthos. A distinctive feature of many pockmarks is a linear scour mark that extends several tens of metres (up to 150 m) from pockmark depressions. Previous numerical and flume tank simulations have shown that scouring of pockmarks occurs in the direction of the dominant near-seabed flow. These geomorphic features may therefore serve as a proxy for local-scale bottom currents, which may in turn inform on sediment processes operating in these areas and contribute to the understanding of the distribution of biodiversity. This study focused on characterising these seabed scoured depressions and investigating their potential as an environmental proxy for habitat studies. The study used ArcGIS spatial analyst tools to quantify the features and explored their potential relationships with other variables (e.g. multibeam backscatter, regional modelled bottom stress, biological abundance and presence/absence) to provide insight into their development, and contribute to a better understanding of the environment surrounding carbonate banks. Preliminary results show a relationship between pockmark types, i.e. with or without scour mark, and backscatter strength. This relationship suggests some additional shallow sub-surface control, mainly related to the presence of buried carbonate bank. In addition, the results suggest that tidal flows are redirected by the banks, leading to locally varied flow directions and 'shadowing' in the lee of the larger banks. This in turn is likely to have an influence on the observed density and abundance of benthic assemblages.

This report provides details of activities undertaken by the Australian Institute of Marine Science (AIMS), Geoscience Australia, the University of Western Australia and the Museum and Art Gallery of the Northern Territory during a marine biodiversity survey to the Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) in 2012. The survey was an activity within the Australian Government's National Environmental Research Program Marine Biodiversity Hub and is a key component of Theme 4 - Regional Biodiversity Discovery to Support Marine Bioregional Plans. Data collected during the survey will be used to support research being undertaken in other Themes of the Marine Biodiversity Hub, including the modelling of ecosystem processes for the northern region, and to support the work programs of the Department of Environment.

This report provides a description of the activities completed during the Bynoe Harbour Marine Survey, from 3 May and 17 May 2016 on the RV Solander (Survey GA4452/SOL6432). This survey was a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and Department of Land Resource Management (Northern Territory Government) and the second of four surveys in the Darwin Harbour Seabed Habitat Mapping Program. This 4 year program (2014-2018) aims to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline information and developing thematic habitat maps that will underpin future marine resource management decisions. The program was made possible through funds provided by the 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 specific objectives of the Bynoe Harbour Marine Survey GA4452/SOL6432 were to: 1. Obtain high resolution geophysical (bathymetry) data for the deeper areas of Bynoe Harbour (<5 m), including Port Patterson; and, 2. Characterise substrates (acoustic backscatter properties, sub-bottom profiles, grainsize, sediment chemistry) the deeper areas of Bynoe Harbour (<5 m), including Port Patterson. Data acquired during the survey included: 698 km2 multibeam sonar bathymetry, water column and backscatter; 102 Smith-McIntyre grabs, 104 underwater camera drops, 29 sub-bottom profile lines and 34 sound velocity profiles.

Geoscience Australia (GA) conducted a marine survey (GA0345/GA0346/TAN1411) of the north-eastern Browse Basin (Caswell Sub-basin) between 9 October and 9 November 2014 to acquire seabed and shallow geological information to support an assessment of the CO2 storage potential of the basin. The survey, undertaken as part of the Department of Industry and Science's National CO2 Infrastructure Plan (NCIP), aimed to identify and characterise indicators of natural hydrocarbon or fluid seepage that may indicate compromised seal integrity in the region. The survey was conducted in three legs aboard the New Zealand research vessel RV Tangaroa, and included scientists and technical staff from GA, the NZ National Institute of Water and Atmospheric Research Ltd. (NIWA) and Fugro Survey Pty Ltd. Shipboard data (survey ID GA0345) collected included multibeam sonar bathymetry and backscatter over 12 areas (A1, A2, A3, A4, A6b, A7, A8, B1, C1, C2b, F1, M1) totalling 455 km2 in water depths ranging from 90 - 430 m, and 611 km of sub-bottom profile lines. Seabed samples were collected from 48 stations and included 99 Smith-McIntyre grabs and 41 piston cores. An Autonomous Underwater Vehicle (AUV) (survey ID GA0346) collected higher-resolution multibeam sonar bathymetry and backscatter data, totalling 7.7 km2, along with 71 line km of side scan sonar, underwater camera and sub-bottom profile data. Twenty two Remotely Operated Vehicle (ROV) missions collected 31 hours of underwater video, 657 still images, eight grabs and one core. This catalogue entry refers to high-resolution imagery taken of piston cores. A total of 20 piston cores collected in water depths between 154-445 m on the continental shelf, were imaged using the Geotek GEOSCAN IV line scan camera. Each core section was imaged at 200 lines per cm, corresponding to a 50 micron pixel size, to produce a single JPG image for each section. For more information on how the piston cores were collected please refer to the post-survey report (follow link at right), or for more information on the MSCL-S please refer to the manual, (follow link at right).

The Casey shallow-water near-shore seabed mapping survey (survey number GA-0348) was conducted as collaboration between Geoscience Australia (GA, Department of Science and Industry), the Royal Australian Navy (RAN, Department of Defence) and the Australian Antarctic Division (AAD, Department of the Environment). The survey was conducted as part of the ongoing AAD program Hydrographic Surveying and Bathymetric Data Acquisition (AAD 3326) and complements a previous charting survey to the Casey region undertaken by RAN and AAD (using the RAN vessel ASV Wyatt Earp) in 2013/14 (also conducted under AAD 3326). The purpose of the survey was to acquire geophysical, geological and biological data from the seabed environment in the shallow (<250 m) coastal waters adjacent to Casey station. The survey acquisition phase formed the main work program for the Antarctic Geoscience Program and Advice activity as part of the Marine Biodiversity and Antarctic Geoscience (MBAG) Section at Geoscience Australia during 2014/15. The shallow water marine environment around Casey station, East Antarctica, is a high use area in the Australian Antarctic Territory, and is frequently visited by the RSV Aurora Australis and smaller vessels conducting scientific research in the area, yet bathymetry data in the area is limited. Additionally, a long-term dive program has revealed the marine habitats in the area host globally 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 climate change, yet extensive knowledge gaps remain, limiting efforts to conserve and manage it effectively.

Geoscience Australia undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, in May 2013. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. 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 principal aim of the Leveque Shelf marine survey 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 Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Jamieson Formation (the seal unit overlying the main reservoir). This dataset comprises total chlorin concentrations and chlorin indices from the upper 2cm of seabed sediments.

Geoscience Australia undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, in May 2013. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. 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 principal aim of the Leveque Shelf marine survey 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 Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Jamieson Formation (the seal unit overlying the main reservoir). This dataset comprises total chlorin concentrations and chlorin indices from the upper 2cm of seabed sediments.

Geoscience Australia undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, in May 2013. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. 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 principal aim of the Leveque Shelf marine survey 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 Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Jamieson Formation (the seal unit overlying the main reservoir). This dataset comprises total chlorin concentrations and chlorin indices from the upper 2cm of seabed sediments.

Geoscience Australia undertook a marine survey of the Leveque Shelf (survey number SOL5754/GA0340), a sub-basin of the Browse Basin, in May 2013. This survey provides seabed and shallow geological information to support an assessment of the CO2 storage potential of the Browse sedimentary basin. The basin, located on the Northwest Shelf, Western Australia, was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. 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 principal aim of the Leveque Shelf marine survey 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 Leveque Shelf area that may extend to the seabed. The survey also mapped seabed habitats and biota to provide information on communities and biophysical features that may be associated with seepage. This research, combined with deeper geological studies undertaken concurrently, addresses key questions on the potential for containment of CO2 in the basin's proposed CO2 storage unit, i.e. the basal sedimentary section (Late Jurassic and Early Cretaceous), and the regional integrity of the Jamieson Formation (the seal unit overlying the main reservoir). This dataset comprises total chlorin concentrations and chlorin indices from the upper 2cm of seabed sediments.