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.

<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).

The effective management of Darwin Harbour in Northern Australia is dependent upon accurate spatial information of seabed habitats that is required by multiple stakeholders. To develop this information, a combination of spatially continuous multibeam data, and targeted video and sediment data were used to classify the seabed and generate habitat maps. These data were acquired during collaborative surveys between Geoscience Australia, the Northern Territory Department of Land Resource Management (DLRM), the Australian Institute of Marine Science and the Darwin Port Corporation. A seascape analysis was used to classify the seabed, incorporating information from multibeam data and underwater video characterisations. We used the Iterative Self Organising Unsupervised Classification technique to combine the information from five variables to form a single classification showing potentially different seabed habitats. The 'probability of hard seabed' (p-rock) variable was derived by comparing the angular backscatter response of known areas of hard seabed to all other angular backscatter responses. We found that six habitat classes were statistically optimal and related to a unique combination of seabed substrate, relief, bedform, presence of a sediment veneer and presence of epibenthic biota and rock/reef. This presentation focuses on methods used to produce a continuous map of the harbour showing the distribution of multiple habitat types. We demonstrate the value of acoustic data for the characterisation of the seabed substrate. The resultant maps are being used by the Northern Territory DLRM to inform ongoing management of Darwin Harbour, with additional mapping planned for offshore areas and adjacent harbours in the region.

This report is the second of three reports that provide the scientific analyses and interpretations resulting from a four-year collaborative habitat mapping program undertaken within the Darwin and Bynoe Harbour region by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and the Northern Territory Government Department of Environment and Natural Resources (DENR). This program was made possible through offset funds provided by the INPEX-operated Ichthys LNG Project to DENR, and co-investments from GA and AIMS.

Acoustic backscatter from the seafloor is a complex function of signal frequency, seabed roughness, grain size distribution, benthos, bioturbation, volume reverberation and other factors. Angular response is the variation in acoustic backscatter with incident angle and it is considered be an intrinsic property of the seabed. The objective of the study was to illustrate how the combination of a self-organising map (SOM) and hierarchical clustering can be used to develop an angular response facies map for Point Cloates, northwest Australia; demonstrate the cluster visualisation properties of the technique; and highlight how the technique can be used to investigate environmental variables that influence angular response.

This resource contains bathymetry and backscatter data for the Oceanic Shoals Commonwealth Marine Reserve (CMR) in the Timor Sea collected by Geoscience Australia during September and October 2012 on RV Solander (survey GA0339/SOL5650). The survey used a Kongsberg EM3002 300 kHz multibeam sonar system mounted in single head configuration to map four areas, covering a combined area of 507 square kilometres. Data are gridded to 2 m spatial resolution. The Oceanic Shoals Commonwealth Marine Reserve survey was undertaken as an activity within the Australian Government's National Environmental Research Program Marine Biodiversity Hub and was the key component of Research Theme 4 - Regional Biodiversity Discovery to Support Marine Bioregional Plans. Hub partners involved in the survey included the Australian Institute of Marine Science, Geoscience Australia, the University of Western Australia, Museum Victoria and the Museum and Art Gallery of the Northern Territory. Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; sub-bottom acoustic profiles; physical samples of seabed sediments, infauna and epibenthic biota; towed underwater video and still camera observations of seabed habitats; baited video observations of demersal and pelagic fish, and; oceanographic measurements of the water column from CTD (conductivity, temperature, depth) casts and from deployment of sea surface drifters. Further information on the survey is available in the post-survey report published as Geoscience Australia Record 2013/38 (Nichol et al. 2013).

This study used angular response curves of multibeam backscatter data to predict the distributions of seven seabed cover types in an acoustically-complex area. Several feature analysis approaches on the angular response curves were examined. A Probability Neural Network model was chosen for the predictive mapping. The prediction results have demonstrated the value of angular response curves for seabed mapping with a Kappa coefficient of 0.59. Importantly, this study demonstrated the potential of various feature analysis approaches to improve the seabed mapping. For example, the approach to derive meaningful statistical parameters from the curves achieved significant feature reduction and some performance gain (e.g., Kappa = 0.62). The first derivative analysis approach achieved the best overall statistical performance (e.g., Kappa = 0.84); while the approach to remove the global slope produced the best overall prediction map (Kappa = 0.74). We thus recommend these three feature analysis approaches, along with the original angular response curves, for future similar studies.

Darwin Harbour is the primary sea port for northern Australia, for which accurate information on the seabed is critical and required by multiple stakeholders. These stakeholders include the offshore energy industry, the fishing industry, and government authorities responsible for managing the harbour, in particular, the Port Authority. Darwin harbour is macrotidal with large areas of shallow (<10 m) subtidal and intertidal flats, dissected by bifurcating channels with localised areas of hardground. These hardground areas provide substrate for epibenthic communities. To support the informed management of Darwin Harbour, Geoscience Australia (GA), in collaboration with the Northern Territory Department of Land Resource Management (DLRM), the Australian Institute of Marine Science (AIMS) and the Darwin Port Corporation, conducted a multibeam survey of the harbour in 2011 on board MV Matthew Flinders. This was followed in 2013 by a physical sampling (sediments and video) survey by GA in collaboration with DLRM on board MV John Hickman. This paper presents results from those surveys with a focus on techniques used to produce a spatially continuous map of the harbour floor showing the distribution of hard and soft substrate types. The Darwin Harbour surveys acquired multibeam sonar data (bathymetry and backscatter) across 180 km2 gridded to 1 m resolution, 61 seabed samples and 35 underwater video observations to map and classify the seabed into habitats. Primary geomorphic features identified in Darwin Harbour include channels, banks, ridges, plains and scarps. Within the study area, acoustically hard substrates are associated with hard ground and relatively coarse seabed sediments. The hard grounds (rock, reef and coral gardens) are found mostly on banks and often overlain by a veneer of sandy sediment. In contrast, acoustically soft substrates are associated with fine sediments (mud and fine sand) that form the plains and channels. A seascape analysis was used to classify the seabed, incorporating information from multibeam data, underwater video characterisations and seabed hardness predictions. We used the Iterative Self Organising (ISO) Unsupervised Classification technique to combine the information from five variables (bathymetry, slope, rugosity, backscatter and probability of hard seabed (p-rock)) to form a single seabed habitat classification. The p-rock variable was derived by comparing the angular backscatter response of known areas of hard seabed to all other angular backscatter responses. We found that six habitat classes were statistically optimal based on the distance ratio measure. These six classes are related to a unique combination of seabed substrate, relief, bedform, presence of a sediment veneer and presence of epibenthic biota and rock/reef (hard substrate). The results presented here demonstrate the value of acoustic data for the characterisation of the seabed substrate that provides key habitats for benthic biota. This study also highlights the utility of the p-rock variable for habitat mapping at the level of distinguishing areas of hard seabed from soft sediment areas. The resultant seabed habitat maps are being used by the Northern Territory DLRM to inform ongoing management of Darwin Harbour, with additional mapping planned for offshore areas and adjacent harbours in the region.

This resource contains backscatter data acquired during the WA Margins Reconnaissance survey, GA-2476 from October 2008 to January 2009 onboard the RV Sonne as part of the Energy Security Program. Almost 230,000 km² of multibeam bathymetry was acquired over the duration of the survey including all transits. Seafloor features revealed by the backscatter and swath bathymetry have shown that geomorphology of the study areas is diverse. The continental slope of the west Australian margin study areas is characterised by large areas with numerous deeply incised canyons and areas with low-angle slumps and scarps mostly on the upper part of the slope. Other geomorphic features on the continental slope include short escarpments of local extent and small volcanic peaks over the Houtman Sub-basin part of the Perth margin. New bathymetry from the Cuvier Plateau has mapped large volcanic domes, some of them with terraces, ridges, a large previously unmapped valley and two large seamounts (newly named the Cuvier Seamount and the Wallaby seamount). See GA Record 2009/38 (Geocat# 69606) for further details on processing methods.

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.