Flythrough movie showing the bathymetry, seabed habitats and biota of the outer continental shelf within the Flinders Commonwealth Marine Reserve (CMR), offshore from Flinders Island northeast Tasmania. The bathymetric image is derived from multibeam sonar collected by Geoscience Australia in 2012 using a 30 kHz Simrad EM3002 system on RV Challenger. Videos and seabed images were collected by the University of Tasmania and CSIRO as part of the same field program. Key features on the shelf bathymetry include low profile reefs, flat sandy seabed and the heads of two submarine canyons. The reefs provide hard substrate for sponge gardens whereas the sand flats are mostly barren. The two submarine canyons are sites of local upwelling, and attract large schools of Tasmanian Striped Trumpeter. The Flinders CMR is a study site for the Marine Biodiversity Research Hub, funded through the National Environmental Research Program (NERP). ..

Topographic Slope grid represents the slope angle (in degree) of an area of seabed. It was created from the bathymetry grid obtained from the survey onboard the Mattew Flinders in 2011. Please see the metadata of the bathymetry grid for details (GeoCat no: 74915).

The local Moran I grid calculates local autocorrelation of the bathymetry grid. It indicates local heterogeneity. The large and positive values represent positive autocorrelation or clumped pattern; the large negative values represent negative autocorrelation or checkerboard pattern; the values close to zero represent random local pattern. The grid was created from the bathymetry grid of Darwin Harbour. Please see the metadata of the bathymetry grid for details (GeoCat no: 74915).

Seafloor bathymetric data and its derivatives fulfil a range of applications that are relevant to supporting the management of marine ecosystems and can provide a potentially powerful physical surrogate for benthic biodiversity. Similarly, morphological and seafloor terrain variables such as slope, curvature and rugosity derived from bathymetry data through GIS analysis not only describe seabed morphology but can also act as proxies for oceanographic processes The distributions of benthic marine fauna and flora most commonly respond to local changes in the topography of the seafloor. When seafloor topography is coupled with biological surveys it can help managers understand which environments contribute most to the growth, reproduction and survival of marine species. These models of habitat suitability provide natural resource managers with a tool with which to visualise the potential habitats of particular species. The accuracy of the habitat suitability models however, is critically reliant on the accuracy of underlying bathymetric data. The uncertainty in the bathymetric data is often ignored and often there is little recognition that the input bathymetric data and the derived spatial data products of the bathymetric data are merely modelled representations of one reality. These models can contain significant levels of uncertainty that are dependent upon the original depth measurements. This research paper explores a method to represent the uncertainty in bathymetric data. We discover that multibeam bathymetry data uncertainties are stochastic at individual soundings but exhibit a distinct spatial distribution with increasing magnitude from nadir to outer beams. We find that the restricted spatial randomness method is able to realistically simulate both the stochastic and spatial characteristics of the data uncertainty. This research concludes that the Monte Carlo method is appropriate for the uncertainty analysis of GIS operations and although the multibeam bathymetry data have notable overall uncertainty level, its impact on subsequent derivative analysis is likely to be minor in this dataset at the 2 m scale. Monitoring and change detection of the seafloor requires detailed baseline data with uncertainty estimates to ensure that features that display change are reliably detected. The accuracy of marine habitat maps and their associated levels of uncertainty are extremely hard to convey visually or to quantify with existing methodologies. The new techniques developed in this research integrate existing statistical techniques in a novel way to improve insights into classification and related uncertainty for seabed habitat maps which will progress and improve resource management for regional and national ocean policy.

Submarine canyons have been recognised as areas of significant ecological and conservation value for their enhanced primary productivity, benthic biomass and biodiversity. In Australia, 753 submarine canyons were mapped on all margins of the continent by the Marine Biodiversity Hub through the Australian Government's National Environmental Research Program. An analysis of canyon geomorphic metrics provided the basis to objectively classify these canyons across a hierarchy of physical characteristics (e.g. volume, depth range, rugosity) separately for shelf-incising and slope-confined canyons (Huang et al., 2014). Here we extend this analysis to include oceanographic variables in presenting a first pass assessment of habitat quality for all canyons on the Australian margin, with a focus on their upper reaches. This study is based on the premise that habitat heterogeneity, productivity and disturbance are the three factors that potentially determine the quality of a canyon habitat. For each factor we derived a range of variables to inform the assessment of habitat quality (see Table). Habitat heterogeneity was measured using a selection of eight geomorphic metrics including canyon volume and rugosity that are considered likely to have a positive relationship with habitat heterogeneity. Canyon productivity was assessed from five variables including: distance to the shelf break as a proxy of nutrient inputs from land and the continental shelf; bottom current speed as an indicator of nutrient supply to benthic epifauna (derived from time-series re-analysis of the BLUElink oceanographic model and in-situ data), and; measures of the probability, frequency and intensity of upwelling (also from BLUElink data). The BLUElink variables have positive relationships with productivity whereas the relationship between distance to shelf and productivity is negative. Benthic disturbance was assessed from the maximum and range of bottom current speeds, and the frequency and intensity of tropical cyclones. According to these relationships, individual canyons were assigned habitat quality scores, first separately for each variable and then aggregated for the three habitat factors. The final scores were obtained by averaging the scores of the three habitat factors. The results show that many submarine canyons on the eastern Australian margin have high habitat quality scores (see Figure). This is interpreted to be mainly due to the influence of the upwelling-favourable East Australian Current which generates high productivity throughout the year. The Albany canyons on the south-western margin also offer high habitat quality for marine species due to complex geometrical and geophysical structures. They also benefit from the upwelling-favourable Flinders Current. In contrast, canyons on the northern and western margins have lower habitat quality. Many of these canyons receive little input from land and continental shelf. In addition, the downwelling- favourable Leeuwin Current, which flows along the western margin of the continent, hampers the supply of deep water nutrients from reaching the upper reaches of canyons, particularly canyon heads that intersect the euphotic zone. Overall, these results provide a framework for targeted studies of canyons aimed at testing and verifying the habitat potential identified here and for establishing monitoring priorities for the ongoing management of canyon ecosystems.

Population connectivity science involves investigating how populations are related to one another through biological dispersal. Here, we review tools, techniques and analyses used by connectivity researchers, and place them in the context of how they can be used by marine managers and policy-makers to enhance their decision-making capabilities. Specific examples of developing technologies include: advances in mark and recapture techniques, underwater imaging systems, population genetic analyses, as well as four-dimensional dispersal simulations (3D space x time). These data can then be analysed using a wide array of analyses, including matrix analysis, graph theory, and various GIS-based routines. The results can be used to identify key source and sink areas, critical linkages (keystones), natural clusters and groups, levels of accuracy, precision and variability, as well as areas of asymmetric exchange. In turn, this information can be used to help identify natural management units, to target critical conservation areas, to develop efficient sampling strategies through power analysis, and to negotiate equitable allocation of resources to upstream management in cases where downstream benefits are significant. Through a better understanding of how connectivity science can assist decision-making, we hope to encourage increased uptake of these kinds of information into institutional planning processes.

Studies utilising high-resolution multibeam swath bathymetry datasets to understand the glacial evolution of the previously glaciated Antarctic continental margin are limited, and are particularly meagre for the East Antarctic Continental shelf. Here we present an interpretation of the seafloor geomorphology based on a new swath bathymetry dataset from the shallow-water marine environment of the Windmill Islands, adjacent to the Australian Antarctic research station, Casey. This high resolution (1 m) dataset permits visualisation of geomorphological features preserved on the seafloor in unparalleled detail. The seafloor is dominated by an assemblage of bedrock, glacial and post-glacial features, providing new insight into the behaviour of the ice-sheet in the region during past glacial episodes and its subsequent retreat to present-day conditions. Interpretation of the submarine geomorphology reveals five dominant features: (1) basement fault systems and bedrock `highs (2) meltwater channels, (3) streamlined sub-glacial landforms, (4) moraine ridges and (5) isolated basins and depressions. Distinctive NW-SE trending channels and linear features that represent brittle bedrock fault systems are clearly evident. These sub-parallel basement bedrock faults or joints have been preferentially eroded and widened by glacial action to form narrow channels and preserve typical `U-shaped profiles. A secondary set of SW to WSW trending linear features are characterised by broad eroded channels. The general orientation of the coastline and channels in the region suggest that these linear features fundamentally control the regional coastal and seafloor geomorphology. Regions of bedrock highs, comprised of submarine outcrops of crystalline metamorphic basement, are characterised by complex, rugged and variable topography, forming steep knolls, small shoals and reefs. Numerous channel networks have been incised into crystalline bedrock highs and their meandering nature, orientation and geometry are consistent with meltwater channels formed by subglacial hydrological flow under considerable hydrostatic pressure. They likely formed during a period when the ice-sheet was expanded and grounded over the areas of offshore crystalline bedrock, possibly during the late Pleistocene Glacial Maximum (LGM) or earlier glaciations. Glacial lineations characterised by subdued sub-parallel linear ridges are preserved in basins and appear to have formed from moulding of unconsolidated sediments by overriding ice. The orientation of the lineations are consistent with formation during westward expansion of the Law Dome ice-sheet onto the continental shelf during the LGM. Regular and closely-spaced arcuate moraine ridge sets are preserved mostly within the prominent NW-trending U-shaped channels. These features appear to be a sequence of recessional moraines or push moraine banks recording slow or episodic retreat of channelized valley glaciers or outlet ice-streams which appear strongly controlled by the local bathymetry. There are several enclosed basins and shallow depressions between bedrock highs with varying degrees of post-glacial sedimentary infill. There is little evidence of reworking of sediments by currents and as a result, the glacial features in this dataset are well preserved. Interpretation of submarine glacial landforms using high-resolution swath bathymetry, integrated with existing information of local ice-sheet evolution from terrestrial studies, allows us to enhance our understanding of the ice-sheet dynamics in the Windmill Islands region.

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) biophysical dispersal model to simulate the movement of marine larvae over large, topographically complex areas. 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.

This is a compilation of all the processed multibeam bathymetry data that are publicly available in Geoscience Australia's data holding for the Macquarie Ridge.

Geoscience Australia carried out a marine survey on Lord Howe Island shelf (NSW) in 2008 (SS062008) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments and infauna, rock coring, observation of benthic habitats using underwater towed video, and measurement of ocean tides and wavegenerated currents. Subbottom profile data was also collected to map sediment thickness and shelf stratigraphy. Data and samples were acquired using the National Facility Research Vessel Southern Surveyor. Bathymetric data from this survey was merged with other preexisting bathymetric data (including LADS) to generate a grid covering 1034 sq km. As part of a separate Geoscience Australia survey in 2007 (TAN0713), an oceanographic mooring was deployed on the northern edge of Lord Howe Island shelf. The mooring was recovered during the 2008 survey following a 6 month deployment. lh_4m is an ArcInfo grid of the Lord Howe survey area produced from the processed EM300 bathymetry data of the survey area using the CARIS HIPS and SIPS software.