The planktobenthos is an important area with unique environmental conditions and represents the immediate link between the benthos and the water column. Despite its close links with the seafloor, the planktobenthos has never been deliberately sampled concurrently with the benthos. We have developed a new method for planktobenthic sampling which allows concurrent collection of benthic and suprabenthic specimens. The Mounted Assembly for Planktobenthic Sampling (MAPS) uses a novel tri-layered net with a seafloor-triggered opening and closing mechanism attached to an epibenthic sled. The MAPS was deployed on the Carnarvon Shelf in Western Australia and was successful at separately sampling both benthic and planktobenthic fauna. A wide variety of epibenthic and infaunal animals were collected from the sled while planktobenthic animals such as mysids were identified from all three nets. The tri-layered net was particularly effective at collecting a broad range of planktobenthic organisms, including smaller fragile larvae and adults which may have otherwise been destroyed during collection in a single net. The number of species in planktobenthic and benthic samples was correlated, although the strength and significance of this relationship varied among taxonomic groups. Importantly, the MAPS can be modified for use on a wide variety of benthic sleds to target a range of organisms. The concurrent collection of planktobenthic and benthic biota will contribute to a range of research areas, including larval ecology, nutrient cycling, biogeography and surrogacy research.

Physical and biological characteristics of benthic communities are analysed from underwater video footage collected across the George V Shelf during the 2007/2008 CEAMARC voyage. Benthic habitats are strongly structured by physical processes operating over a range of temporal and spatial scales. Iceberg scouring recurs over timescales of years to centuries along shallower parts of the shelf, creating communities in various stages of maturity and recolonisation. Upwelling of modified circumpolar deep water (MCDW) onto the outer shelf and cross-shelf flow of high salinity shelf water (HSSW) create spatial contrasts in nutrient and sediment supply, which are largely reflected in the distribution of deposit and filter feeding communities. Long term cycles in the advance and retreat of icesheets (over millennial scales) and subsequent focussing of sediments in troughs such as the Mertz Drift create patches of consolidated and soft sediments, which also provide distinct habitats for colonisation by different biota. These physical processes of iceberg scouring, current regimes and depositional environments, in addition to water depth, are important factors in the structure of benthic communities across the George V Shelf. The modern shelf communities mapped in this study largely represent colonisation over the past 8,000-12,000 years, following retreat of the icesheet and glaciers at the end of the last glaciation. Recolonisation on this shelf may have occurred from two sources: deep-sea environments and possible shelf refugia on the Mertz and Adélie Banks. However, any open shelf area would have been subject to intense iceberg scouring. Understanding the timescales over which shelf communities have evolved and the physical factors which shape them will allow better prediction of the distribution of Antarctic shelf communities and their vulnerability to change. This knowledge can aid better management regimes for the Antarctic margin.

Reliable marine benthic habitat maps at regional and national scales are needed to enable the move towards the sustainable management of marine environmental resources. The most effective means of developing broad-scale benthic habitat maps is to use commonly available marine physical data due to the paucity of adequate biological data and the prohibitive cost of directly sampling benthic biota over large areas. A new robust method of mapping marine benthic habitats at this scale was developed based on a stratified approach to habitat classification. This approach explicitly uses knowledge of marine benthic ecology to determine an appropriate number of stratification levels, to choose the most suitable environmental variables for each level, and to select ecologically significant boundary conditions (i.e. threshold values) for each variable. Three stratification levels, with nine environmental variables, were created using a spatial segmentation approach. Each level represents major environmental processes and characteristics of the Australian marine benthic environment. The finest scale of benthic habitat is represented by seafloor physical properties of topography, sediment grain size and seabed shear stress. Water-column nutrient parameters and bottom water temperature depicted the intermediate scale, while the broadest scale was defined by seabed insolation parameters derived from depth data. The classifications of the three stratified levels were implemented using an object-based fuzzy classification technique that recognises that habitats are largely homogenous spatial regions, and transitions between habitats are often gradual. Classification reliability was indicated in confidence maps. Physical habitat diversity was evaluated for the final benthic habitat map that combines the three classifications. The final benthic habitat map identifies the structurally complex continental shelf break as an area of relatively high habitat diversity. Continental Shelf Research

Geoscience Australia has undertaken a classification of biophysical datasets to create seabed habitat maps (termed 'seascapes') for the Australian margin and adjacent sea floor. Seascapes describe a layer of ecologically meaningful biophysical properties that spatially represents potential seabed habitats. Each seascape area corresponds to a region of the seabed that contains similar biophysical properties and, by association, potential habitats and communities. This dataset is a seascape classification for the on-shelf zone of the North-west bioregion. The on-shelf zone is separated from the off-shelf zone due to the availability of the effective disturbance layer for the on-shelf zone only. Also, a higher resolution sea floor temperature layer has been used in the on-shelf analysis.

Pitcher, C.R., P.J., Doherty, and T.J. Anderson. (2008). Seabed environments, habitats and biological assemblages. pages 51-58. In: Hutchings, P.A., M.J. Kingsford, and O. Hoegh-Guldberg (eds.). The Great Barrier Reef: Biological, Environment and Management. CSIRO Publishing, Springer.

Seabed mapping studies are supporting the regulation and management of a range of competing industries in northern Australia. These industries include fishing and an expanding offshore energy sector, with new developments to include seabed pipelines and subsurface storage of CO2. Set in tropical waters, the northern Australian shelf is also recognised in marine management plans for its high-value marine biodiversity associated with a complex geomorphology. To reduce uncertainty and risk in the future development and management of this region, the Australian Government is supporting seabed mapping research under a series of programs aimed at delivering integrated information relevant to infrastructure development (Offshore Energy Security Program, 2007-2010), offshore storage of CO2 in deep sedimentary basins (National CO2 Infrastructure Program, 2011-2015) and biodiversity conservation of the marine estate (National Environmental Research Program, 2011-2014). In 2009 and 2010, Geoscience Australia undertook collaborative seabed mapping surveys to deliver to these programs, with an initial focus on the eastern Joseph Bonaparte Gulf (Timor Sea). Objectives were to: characterise the physical and biological properties of the seabed in representative areas; assess potential geohazards, and; identify unique or sensitive benthic habitats.

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.

The Marine Science Voyage (2010/11 VMS) to the Mertz Glacier region was a collaborative survey involving scientists from a number of research institutions, working across a number of different projects, with the overall aim of conducting a coordinated and comprehensive study to measure and monitor the impact of the Mertz Glacier calving event on the local and regional environment. The survey took place in January 2011 and enabled the collection of data shortly after the calving event so that physical, chemical and biological changes in response to the new conditions can be monitored over time. As such, data collected on VMS will provide a benchmark for tracking future change in the Mertz Glacier region environment. Geoscience Australia and the Australian Antarctic Division conducted a benthic community survey during the voyage. The purpose of the benthic community survey was to collect high-resolution still images of the sea floor to address three main objectives: 1. to investigate benthic community composition in the area previously covered by the MGT and to the east, an area previously covered by approximately 30 m of fast ice; 2. to investigate benthic community composition (or lack thereof) in areas of known iceberg scours; and 3. to investigate the lateral extent of hydrocoral communities along the shelf break. The survey collected over 1800 images of the sea floor on the continental shelf and slope in the Mertz Glacier region, including in the area previously covered by the Mertz Glacier tongue. There were 75 successful camera deployments and a further 7 stations where images were of poor quality but may still provide useful information. The benthic images will be examined in detail to provide information on benthic community composition and substrate type. The survey has provided a major new set of data which will greatly enhance the understanding of Antarctic marine biodiversity and the relationship between physical conditions and benthic communities.

This chapter presents a broad synthesis and overview based on the 57 case studies included in Part 2 of this book, and on questionnaires completed by the authors. The case studies covered areas of seafloor ranging from 0.15 to over 1,000,000 km2 (average of 26,600 km2) and a broad range of geomorphic feature types. The mean depths of the study areas ranged from 8 to 2,375 m, with about half of the studies on the shelf (depth <120 m) and half on the slope and at greater depths. Mapping resolution ranged from 0.1 to 170 m (mean of 13 m). There is a relatively equal distribution of studies among the four naturalness categories: near-pristine (n=17), largely unmodified (n = 16), modified (n=13) and extensively modified (n=10). In terms of threats to habitats, most authors identified fishing (n=46) as the most significant threat, followed by pollution (n=12), oil and gas development (n=7) and aggregate mining (n=7). Anthropogenic climate change was viewed as an immediate threat to benthic habitats by only three authors (n=3). Water depth was found to be the most useful surrogate for benthic communities in the most studies (n=17), followed by substrate/sediment type (n=14), acoustic backscatter (n=12), wave-current exposure (n=10), grain size (n=10), seabed rugosity (n=9) and BPI/TPI (n=8). Water properties (temperature, salinity) and seabed slope are less useful surrogates. A range of analytical methods were used to identify surrogates, with ARC GIS being by far the most popular method (23 out of 44 studies that specified a methodology).

This report provides a description of the CERF Marine Biodiversity Hub's survey of the Carnarvon Shelf, Western Australia, in August and September, 2008. The survey was a collaboration between the Australian Institute of Marine Science (AIMS) and Geoscience Australia (GA) aboard RV Solander, as part of the Hub's Surrogates Program. The purpose of field surveys in the Surrogates Program is to collect high-quality, accurately co-located data to enable the robust testing of a range of physical parameters as surrogates of patterns of benthic biodiversity in strategically selected, spatially discrete areas that are representative of much broader benthic environments. The report describes the methods employed in the survey and the datasets collected. Additional processing of most of the physical data (wave and current measurements, multibeam sonar bathymetry and backscatter, sediment grab samples, acoustic sediment profiles) and biological data (towed underwater video and stills photography, bottom sediment samples, near-bottom plankton samples) collected is required before comparative analysis between the data sets can commence. However, a number of initial interpretations of the physical data have been made and examples of the types of biota encountered in the towed video and stills photography and initial interpretations of the benthic communities encountered, are provided. The survey was focussed on three strategically selected study areas on the southern Carnarvon Shelf at Mandu, Point Cloates and Gnaraloo. A small additional area was also examined near the Muiron Islands, in the mouth of Exmouth Gulf, at the end of the survey.