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Systematic conservation planning requires spatial information on biodiversity. Such information is often unavailable, forcing spatial planning to rely on assumed relationships between species and environmental features. This problem is particularly acute in large, remote marine protected areas that are proliferating rapidly. Here, we use models to predict whether (a) macrobenthic biodiversity across four taxa (gorgonians, soft corals, hard corals, and sponges) with different life histories are congruent within seascape features through regional space; and (b) models generated in an intensively‐sampled area in one region can predict the occurrence of habitat‐forming macrobenthos in neighboring ones. All four taxa studied showed similar habitat preferences, but high variability in distributions among and within features suggesting factors other than simple geomorphology influence these regional biodiversity patterns. Nonetheless, models derived from one region accurately predicted the presence and absence of the same taxa hundreds of kilometers away. This transferability of models of species occurrences has the potential to deliver improved reserve design in data‐deficient regions.

The Oceanic Shoals Marine Park is located within the Timor Sea offshore northern Australia and was established due to the conservation values associated with carbonate bank and terrace systems in the region. Between 2009 and 2012, ten grids covering ~3100 km2 were mapped and associated biological samples and benthic imagery collected. We describe three of these grids in detail, including banks but also other geomorphic features: the western grid includes banks that are characterized by flat tops and relatively steep sides supporting sponge gardens; the central grid is characterized by shallow channels and plains with low ridges, pockmarks, and depressions and associated rich polychaete communities; and the eastern grid encompasses a north–south oriented valley with flanking terraces and banks that supported sessile invertebrate assemblages, including dense reef-forming corals. Imagery data was applied to a predictive habitat map for the marine park. Sponge and polychaete biodiversity are characterized, but no strong environmental surrogates were identified. Overall, our geological and biological analyses confirm and further describe the carbonate banks and shoals as a key ecological feature in the Oceanic Shoals Marine Park.

A high-resolution multibeam echosounder (MBES) dataset covering over 279,000 km2 was acquired in the southeastern Indian Ocean to assist the search for Malaysia Airlines Flight 370 (MH370) that disappeared on 8 March 2014. The data provided an essential geospatial framework for the search and is the first large-scale coverage of MBES data in this region. Here we report on geomorphic analyses of the new MBES data, including a comparison with the Global Seafloor Geomorphic Features Map (GSFM) that is based on coarser resolution satellite altimetry data, and the insights the new data provide into geological processes that have formed and are currently shaping this remote deepsea area. Our comparison between the new MBES bathymetric model and the latest global topographic/bathymetric model (SRTM15_plus) reveals that 62% of the satellite-derived data points for the study area are comparable with MBES measurements within the estimated vertical uncertainty of the SRTM15_plus model (± 100 m). However, > 38% of the SRTM15_plus depth estimates disagree with the MBES data by > 100 m, in places by up to 1900 m. The new MBES data show that abyssal plains and basins in the study area are significantly more rugged than their representation in the GSFM, with a 20% increase in the extent of hills and mountains. The new model also reveals four times more seamounts than presented in the GSFM, suggesting more of these features than previously estimated for the broader region. This is important considering the ecological significance of high-relief structures on the seabed, such as hosting high levels of biodiversity. Analyses of the new data also enabled sea knolls, fans, valleys, canyons, troughs, and holes to be identified, doubling the number of discrete features mapped. Importantly, mapping the study area using MBES data improves our understanding of the geological evolution of the region and reveals a range of modern sedimentary processes. For example, a large series of ridges extending over approximately 20% of the mapped area, in places capped by sea knolls, highlight the preserved seafloor spreading fabric and provide valuable insights into Southeast Indian Ridge seafloor spreading processes, especially volcanism. Rifting is also recorded along the Broken Ridge – Diamantina Escarpment, with rift blocks and well-bedded sedimentary bedrock outcrops discernible down to 2400 m water depth. Modern ocean floor sedimentary processes are documented by sediment mass transport features, especially along the northern margin of Broken Ridge, and in pockmarks (the finest-scale features mapped), which are numerous south of Diamantina Trench and appear to record gas and/or fluid discharge from underlying marine sediments. The new MBES data highlight the complexity of the search area and serve to demonstrate how little we know about the vast areas of the ocean that have not been mapped with MBES. The availability of high-resolution and accurate maps of the ocean floor can clearly provide new insights into the Earth's geological evolution, modern ocean floor processes, and the location of sites that are likely to have relatively high biodiversity.

Spatial information on the distribution of seabed substrate types in high use coastal areas is essential to support their effective management and environmental monitoring. For Darwin Harbour, a rapidly developing port in northern Australia, the distribution of hard substrate is poorly documented but known to influence the location and composition of important benthic biological communities (corals, sponges). In this study, we use angular backscatter response curves to model the distribution of hard seabed in the subtidal areas of Darwin Harbour. The angular backscatter response curve data were extracted from multibeam sonar data and analysed against backscatter intensity for sites observed from seabed video to be representative of “hard” seabed. Data from these sites were consolidated into an “average curve”, which became a reference curve that was in turn compared to all other angular backscatter response curves using the Kolmogorov–Smirnov goodness-of-fit. The output was used to generate interpolated spatial predictions of the probability of hard seabed (p-hard) and derived hard seabed parameters for the mapped area of Darwin Harbour. The results agree well with the ground truth data with an overall classification accuracy of 75% and an area under curve measure of 0.79, and with modelled bed shear stress for the Harbour. Limitations of this technique are discussed with attention to discrepancies between the video and acoustic results, such as in areas where sediment forms a veneer over hard substrate.

Following the establishment of the world’s largest network of marine protected areas, Australia is now tasked with implementing national plans to manage a huge range of marine environments, from tropical to sub-Antarctic climates and shallow reef to abyssal depths. Monitoring (i.e. condition assessment and trend detection) is one of the key objectives of associated management plans. As part of a national effort to acquire baseline data for future monitoring purposes from 2009 to 2012, we collected geoscientific (bathymetry, backscatter, sub-bottom profiles, sediment grain-size) and biological data (assemblages and richness of infauna, sponges and pelagic fish) using a variety of gear (grab, sled, pelagic baited video, multibeam sonar, sparker) from the Oceanic Shoals Australian Marine Park in northern Australia. In this presentation, we describe how the integration of such data (including derived geoscientific products) helped to inform sampling design, map habitats, predict the distribution of benthic and pelagic communities at varying spatial scales, and better understand ecosystem processes. We hope to encourage ecologists and marine managers to incorporate geoscientific methods into their research and policy in order to further improve sampling design, data collection, robust modelling, and informed decision-making.

A rich trove of marine geophysical data acquired in the search for missing flight MH370 is yielding knowledge of ocean floor processes at a level of detail rare in the deep ocean.

Many countries are now using or investigating offshore geological storage of CO2 as a means to reduce atmospheric CO2 emissions. Although associated research often focuses on deep-basin geology (e.g. seismic, geomagnetics), environmental data on the seabed and shallow subseabed is also crucial to (1) detect and characterise potential indicators of fluid seeps and their potential connectivity to targeted storage reserves, (2) obtain baseline environmental data for use in future monitoring, and (3) acquire information to facilitate an improved understanding of ecosystem processes for use in impact prediction. This study reviews the environmental considerations, including potential ecological impacts, associated with subseabed geological storage of CO2. Due to natural variations in CO2 levels in seafloor sediments, baseline CO2 measurements and knowledge of physical–chemical processes affecting the regional distribution of CO2 and pH are critical for the design of appropriate monitoring strategies to assess potential impacts of CO2 seepage from subseabed storage reservoirs. Surficial geological and geophysical information, such as that acquired from multibeam sonar and sub-bottom profiling, can be used to investigate the connectivity between the deep reservoirs and the surface, which is essential in establishing the reservoir containment properties. CO2 leakage can have a pronounced effect on sediments and rocks which in turn can have carryover effects to biogeochemical cycles. The effects of elevated CO2 on marine organisms are variable and species-specific but can also have cascading effects on communities and ecosystems, with marine benthic communities at some natural analogue sites (e.g. volcanic vents) showing decreased diversity, biomass, and trophic complexity. Despite their potential applications, environmental surveys and data are still not a standard and integral part of subseabed CO2 storage projects. However, the habitat mapping and seabed characterisation methodology that underpins such surveys is well developed and has a strong record of providing information to industry and decision makers. This review provides recommendations for an integrated and interdisciplinary approach to offshore geological storage of CO2, which will benefit national programs and industry and will be valuable to researchers in a broad range of disciplines.

The extent to which fluids may leak from sedimentary basins to the seabed is a critical issue for assessing the potential of a basin for carbon capture and storage. The Petrel Sub-basin, located beneath central and eastern Joseph Bonaparte Gulf in tropical northern Australia, was identified as potentially suitable for the geological storage of CO2 because of its geological characteristics and proximity to offshore gas and petroleum resources. In May 2012, a multidisciplinary marine survey (SOL5463) was undertaken to collect data in two targeted areas of the Petrel Sub-basin to facilitate an assessment of its CO2 storage potential. This paper focuses on Area 1 of that survey, a 471 km2 area of sediment-starved shelf (water depths of 78 to 102 m), characterised by low-gradient plains, low-lying ridges, palaeo-channels and shallow pockmarks. Three pockmark types are recognised: small shallow unit pockmarks 10–20 m in diameter (generally

Seafloor channel systems are well developed in several British Columbia (Canada) fjords, including Knight, Bute and Toba inlets. The channels are active conduits for turbidity currents during episodic failures of delta fronts at the fjord heads. Recently acquired swath multibeam bathymetric data enabled a complete and detailed assessment of the form of these channel systems. Repeated multibeam surveys in Bute and Toba inlets (Mar. 2008 and Nov. 2010) indicate that the deeply incised channels may undergo accretion or erosion over a period as short as 2.5 years. Locally significant (>15 m) bathymetric changes were documented in the channel systems, with bathymetric differences exceeding 5 m occurring along approx. 20–25% of the resurveyed channel lengths. Slope failure involving the upper delta front observed in Toba Inlet is a mechanism for the rapid initiation of new channel segments. Sediment accretion on the inner side of some channel bends indicates that point bars may form as lateral channel migration proceeds. Channel sidewall slumps are found at some outer channel bends and mounded deposits may occur at these sites. Lateral migration is accompanied by outer bend erosion, overall deepening of the channel and the development of terraces.

The Pacific margin of Canada has been subjected to tectonism, dramatic sea level change and vigorous storm and tidal energy since glacial times resulting in a complex seafloor. Extensive multibeam mapping of this shelf has provided an opportunity to understand how these processes have impacted sedimentology and morphology. Bathymetric restriction of the tidally dominated flow between the inland seas and the open Pacific has resulted in the development of very large subaqueous dune fields and terrace moats. For example, in the southern Strait of Georgia nearly symmetrical dunes with wavelengths between 100 and 300 m, dune heights up to 28 m, cover the seafloor in 170–210 m water depth. In northern Hecate Strait a 72 km2 area of large 2D dunes occurs at the transition with Dixon Entrance which opens to the Pacific Ocean and steep (>10°) wave-cut terraces and drowned spits, a result of sea level changes during the Holocene, are now being undercut to generate moats 7 m deep, in a narrowing shelf trough. Currents, with velocities ranging between 0.2 and 2.2 m s−1, are dominated by semi-diurnal tidal streams that are continually modified by wind and estuarine circulation. There appears to be a clear association of grain size, water depth and flow velocity controlling the size of the subaqueous dunes.

Publisher Summary The western margin of Canada is a tectonically complex region where many geological processes have contributed to a coastal and nearshore zone mainly dominated by bedrock geology. The coastal and submarine landscape has developed as a consequence of regional accretionary tectonics, resulting in the development of a broad zone of deformation and mountain building forming a margin parallel, insular belt of mountains apparent as two main island land masses, Haida Gwaii and Vancouver Island, while deep sedimentary basins have repeatedly formed on the adjacent continental shelf due to the same tectonic processes. Juan Perez Sound in northern British Columbia and Northumberland Channel in the south are geographically remote and distinct in their bedrock geologic composition, structure, and geomorphology. Within the 70-km2 study areas (0–300 m in water depth), inshore rockfish ( Sebastes spp.) and spotted ratfish ( Hydrolagus colliei ) habitats are delineated from a multiband raster (multibeam bathymetry, six derived terrain layers, and backscatter strength) using point locations of these observed species to extrapolate class probability layers. The spotted ratfish class probability layer, representing noninshore rockfish habitat, is then subtracted from the inshore rockfish layer to derive an exclusive inshore rockfish habitat probability layer. This layer is consistent with bedrock areas identified within the study sites. Correspondence analysis of visual substrata and fish species data confirm that inshore rockfish habitat is well described by bedrock and cobble substrata with their corresponding dominant rockfish species assemblage and spotted ratfish (noninshore rockfish) habitat is described by gravel and mud substrata with their corresponding dominant round fish and flat fish species groups.

Publisher Summary Inland seas are landlocked seas that are only connected to the ocean through narrow channels. They usually contain many islands, channels, sounds, and straits. Inland sea was first defined for the Seto Inland Sea, separating the three main islands of Japan and connected to the Pacific Ocean through narrow channels. It is one of the world's largest inland seas, encompassing 400 islands, 7,500 km of coastline, water depths to 650 m in the coastal fjords, and an overall marine area of 17,000 km2. This chapter summarizes the primary geomorphic features and identifies known associated habitat characteristics for the entire Inland Sea. There is a limited biological database for the Salish Sea, so only those biological features associated with geomorphic features that have been studied and published are presented. No quantitative studies of the biological communities exist for each geomorphic feature. There is considerable descriptive information pertaining to benthos of the Salish Sea, however, and based on this qualitative information several aspects of benthic habitat for some geomorphic features can be highlighted. The inland sea developed through Pleistocene glacial processes and the resultant geography provides for a meso- to macrotidal environment. Typical features found are shallow banks, deltas, fjords, glacial troughs, bedrock, subaqueous dune fields, and sponge reefs. The past and present physical processes have created a variety of habitats, such as steep, near-vertical rock walls, and stacked boulders, which offer habitat for juvenile and adult rockfish, subaqueous dunes that shelter sand lances, mud flats that provide habitat for a variety of shellfish and birds, and raised glacial banks that allow for the formation of siliceous (glass) sponge reefs.

This paper presents a review of sediment dispersal processes in the Strait of Georgia, based on marine geological studies. Sediment from the Fraser River is dispersed around the Strait through a variety of transport pathways. Most sand and coarser silt fractions settle out and are deposited within a few 100 m of the channel mouths. Both channelled and non-channelled gravity flows probably transport sediment downslope and onto the basin floor. Asymmetric tidal currents force a predominantly northward sediment drift, resulting in a reworked slope off Roberts Bank and a finer-grained depositional slope off Sturgeon Bank. Far-field sediment accumulation is controlled by local morphology and sediment dynamics. Multibeam mapping and seismic profiling reveal that some parts of the basin floor are characterized by bottom sediment reworking and erosion. Given the complexities of sediment dispersal and seafloor reworking, generalizations about sediment dispersal paths and sedimentation rates are difficult. Future understanding will be advanced by the cabled observatory, VENUS, which will enable near real-time monitoring of key processes.

The reef-forming scleractinian coral, Lophelia pertusa has been recovered in bottom samples and observed as a dense debris field during remote-operated vehicle transects on a terrace on the flank of a steep-sided seamount-like knoll in the central Strait of Georgia, British Columbia. The coral debris has a minimum thickness of 33 cm and extends over several hectares in water depths of 225 to 255 m, suggesting that the coral community dominated this site for several centuries. Lophelia pertusa forms extensive reefs in many regions of the world, suggesting that a cold-water coral reef existed at this site in the recent past. This site and a sample from the west coast of Vancouver Island represent the first recognized British Columbia occurrences of Lophelia pertusa. In addition, regional multibeam surveys have revealed the presence of small (< 1 square km) Hexactinellid sponge reefs in waters 100 to 140 mdeep along the eastern approaches to the Gulf Islands in the southern Strait of Georgia in areas of low-relief glacial deposits. The surfaces of these reefs are covered with large Hexactinosidan sponges, predominately Heterochone calyx and Aphrocallistes vastus, or mantled with broken sponges where anthropogenic impacts, including trawling, have occurred. Mapping of these and other sensitive habitats will allow effective ocean management measures to be undertaken by the responsible agencies.