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.

Permeable, sandy sediments cover most of the continental shelf. The important role of pore-water advective flow on biogeochemical processes in these sediments has been highlighted in recent studies. Such flow can be driven by wave-action, water-density and interactions between topography and bottom currents, in addition to biological activity, and can create spatially complex and highly dynamic benthic environments in which processes vary on timescales ranging from minutes to months. It is well known that the patchiness of soft sediment (organic matter/bacteria, particle diversity, redox) is likely to be a major determinant of species diversity, but previous studies have not specifically defined patches based on a range of biologically-relevant physico-chemical variables, nor observed how patches change across time. This study, as part of the Surrogates Program in the Commonwealth Environmental Research Facilities Marine Biodiversity Hub, investigated temporal changes in the geochemistry, physical sediments and infauna of sandy sediments in Jervis Bay at two times.

This special issue of Continental Shelf Research presents 13 research papers that contain the latest results in the field of benthic marine environment mapping and seabed characterisation. A total of 10 papers in this special issue were presented as papers and posters at GeoHab conferences in 2007 (Noumea, New Caledonia), 2008 (Sitka, Alaska) and 2009 (Trondheim, Norway). The annual GeoHab conference provides a forum in which marine physical and biological scientists, managers, policy makers, and industry representatives can convene to engage in discussions regarding mapping and characterising the seabed. The papers contained in this special issue build on the work published in Greene and Todd (2005): Mapping the Seafloor for Habitat Characterization, a special publication of the Geological Association of Canada.

Explaining spatial variation and habitat complexity of benthic habitats from underwater video through the use of maps. Different methodologies currently used to process and analyse percent cover of benthic organisms from underwater video will be addressed and reviewed.

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.

Anthropogenic global ocean warming is predicted to cause bleaching of many near-sea-surface (NSS) coral reefs and could make deep-water, mesophotic coral ecosystems (MCEs) into coral reef 'life boats', for many coral species. The question arises: how common are MCE's in comparison to NSS reefs? We used a dataset from the Great Barrier Reef (GBR) to show that only about 37% of available bank surface area is colonised by NSS coral reefs (16,110 km2); the other 63% of submerged bank area (25,599 km2) represents potential MCE habitat and it is spatially distributed along the GBR continental shelf in direct proportion to NSS coral reefs. Out of 25,599 km2 of submerged bank area, predictive habitat modelling indicates that about 52% (13,000 km2) is MCE habitat.

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.

In this review we aim to synthesise physical and biological information on the Lord Howe Rise (LHR) region to describe its biogeography at a regional scale (100s of kilometres) and assess this in a national and global context. The LHR region is large (1.95 million km2), spans tropical and cool temperate latitudes (18.4oS to 40.3oS), and is topographically complex being formed of large expanses of soft sediment basins and plateaus (i.e. subdued bathymetric features), with scattered seamounts, guyots, knolls, and pinnacles (i.e. raised bathymetric features). Physical factors can vary between these two broad feature types, particularly regarding depth and substrate, although no clear relationship was detected between sediment texture and geomorphic features across the survey area. Biological data from two recent surveys (TAN0713 and NORFANZ) show differences in assemblages and species distribution between raised and subdued bathymetric features and suggest that biological communities are indeed influenced by substrate as well as depth-related variables, with some taxa such as demersal fish showing latitudinal gradients. There are only limited spatially-replicated studies and no time-series data available for most of the LHR region, but paleo-environmental processes and examples from other regions provide some indication of migration, speciation, and endemism in the LHR region.

This introductory chapter provides an overview of the book's contents and definitions of key concepts including benthic habitat, potential habitat and seafloor geomorphology. The chapter concludes with a summary of commonly used habitat mapping technologies. Benthic (seafloor) habitats are physically distinct areas of seabed that are associated with particular species, communities or assemblages that consistently occur together. Benthic habitat maps are spatial representations of physically distinct areas of seabed that are associated with particular groups of plants and animals. Habitat maps can illustrate the nature, distribution and extent of distinct physical environments present and importantly they can predict the distribution of the associated species and communities.

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.