Geoscience Australia carried out marine surveys in Jervis Bay (NSW) in 2007, 2008 and 2009 (GA303, GA305, GA309, GA312) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments (for textural and biogeochemical analysis) and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wavegenerated currents. Data and samples were acquired using the Defence Science and Technology Organisation (DSTO) Research Vessel Kimbla. Bathymetric mapping, sampling and tide/wave measurement were concentrated in a 3x5 km survey grid (named Darling Road Grid, DRG) within the southern part of the Jervis Bay, incorporating the bay entrance. Additional sampling and stills photography plus bathymetric mapping along transits was undertaken at representative habitat types outside the DRG. This 126 sample dataset comprises chlorophyll a and pheophytin a measurements on surface seabed sediments (~0 to 2 cm) from Jervis Bay.

Physical and biological characteristics of benthic communities on the George V Shelf have been analysed from underwater camera footage collecting during Aurora Australis voyages in 2007/08 and 2010/11. The 2007/08 data revealed a high degree of variability in the benthic communities across the shelf, with the benthic habitats strongly structured by physical processes. Iceberg scouring recurs over timescales of years to centuries along shallower parts of this 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 interacting 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. In February 2010, iceberg B09B collided with the Mertz Glacier Tongue, removing about 80% or 78km from the protruding tongue. This event provided a rare opportunity to access a region previously covered by the glacier tongue, as well as regions to the east where dense fast ice has built up over decades, restricting access. The 2010/11 voyage imaged 3 stations which were previously beneath the floating tongue, as well as 9 stations covered by multi-year and annual fast ice since the mid 1970s.

The Joseph Bonaparte Gulf and Timor Sea region (JBG-TS) is an area of significance for multiple resource needs, from marine planning to offshore industry development. As such, information on seabed environments in this region is of interest to both industry and marine management. Geoscience Australia is focussed on the collation and preparation of regional pre-competitive environmental datasets, the outputs of which can be used for pre and post-bid environmental assessments and for emergency response planning. This report provides a spatial synthesis of seabed environments for the Joseph Bonaparte Gulf and Timor Sea region (JBG-TS) by identifying and describing significant habitats, communities, and potential geohazards. Data are sourced from existing literature, including publicly available industry data, as well as data collected from two seabed mapping surveys to the Van Diemen Rise in the eastern Timor Sea (GA-322 and GA-325).

This study investigated bio-environment relationships in Jervis Bay, a sandy partially enclosed embayment in NSW. Three decision tree models and a robust model selection process were applied to a wide-range of physical data (multibeam bathymetry and backscatter grids and derivatives, parameters that describe seabed sediment and water column physical/geochemical characteristics, seabed exposure) and co-located biological data. The models for selected infaunal species and three diversity indices explained 32-79% of data variance. Patterns of abundance and diversity were statistically related to a wide range of environmental variables, including sediment physical (e.g. mud, CaCO3, gravel) and geochemical properties (e.g. chlorophyll a, total sediment metabolism, total sulphur), seabed morphometric characteristics (e.g. local Moran's I of bathymetry, rugosity), seabed exposure regime and water column light attenuation. The modelled response curves together with results from an earlier habitat mapping study informed the development of a conceptual model that provides a process-based framework for the interpretation of biodiversity patterns in the southern part of the Bay. The conceptual model had three zones which were noted for: (i) fine-sediment resuspension and macroalgae accumulation (leading to anoxia; extreme); (ii) bioturbation (in-between); and (iii) exposure of the seabed to waves (extreme in places). Most bio-environment relationships pointed to complex relationships between multiple biological and physical factors occurring in the different process domains/zones. The combined use of co-located samples and bio-environment and conceptual models enabled a mechanistic understanding of benthic biodiversity patterns in Jervis Bay.

Understanding and predicting the bio-physical relationships between seabed habitats, biological assemblages, and marine biodiversity is critical to managing marine systems. Species distributions and assemblage structure of infauna were examined on the oceanic shelf surrounding Lord Howe Island (LHI) relative to seabed complexity within and adjacent to a newly discovered relict coral reef. High resolution multibeam sonar was used to map the shelf, and identified an extensive relict reef in the middle of the shelf, which separated an inner drowned lagoon from the outer shelf. Shelf sediments and infauna were sampled using a Smith McIntyre grab. The three geomorphic zones (drowned lagoon, relict reef and outer shelf) were strong predictors or surrogates of the physical structure and sediment composition of the LHI shelf and its infaunal assemblage. Infaunal assemblages were highly diverse with many new and endemic species recorded. Each zone supported characteristic assemblages and feeding guilds, with higher abundance and diversity offshore.

Ecoregions are defined in terms of community structure in function of abiotic or even anthropogenic forcing. They are mesoscale structures defined on the potential habitat of species or predicted communities geographic extent. We assume that they can be more easily defined for long-lived species such as benthos or neritic fish in the marine environment. Uncertainties exist for the pelagic realm because of its higher variability, plus little is known about the meso- and bathypelagic zones. A changing environment and modifications of habitats will probably drive new communities from plankton to fish or top predators. We need based-line studies such as those of CAML, databases like SCAR-MarBIN and tools for integrating all of these observations. Our objective is to understand the biodiversity patterns in the Southern Ocean and how these might change.

Geoscience Australia carried out marine surveys in Jervis Bay (NSW) in 2007, 2008 and 2009 (GA303, GA305, GA309, GA312) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments (for textural and biogeochemical analysis) and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wavegenerated currents. Data and samples were acquired using the Defence Science and Technology Organisation (DSTO) Research Vessel Kimbla. Bathymetric mapping, sampling and tide/wave measurement were concentrated in a 3x5 km survey grid (named Darling Road Grid, DRG) within the southern part of the Jervis Bay, incorporating the bay entrance. Additional sampling and stills photography plus bathymetric mapping along transits was undertaken at representative habitat types outside the DRG. This 18 sample data set comprises %TOC, %TN, TOC/TN ratios, carbon and nitrogen isotopic ratios and major and trace element concnetrations of plant and algae tissues from Jervis Bay. The red algae likely belong to the genera Gracilaria edulis and Acrosorium venulosum which are abundant in the Bay, and are often observed to washup on the beaches.

The term 'surrogacy' is used in habitat mapping with reference to the biophysical variables that can be mapped with a quantifiable correspondence to the occurrence of benthic species and communities. Surrogacy research can be defined as an empirical method of determining which easily measured characteristics best describe the species assemblage in a particular space and at a particular time. These characteristics act as predictors (with some known probability and uncertainty) for the occurrence of species assemblages in unexplored areas. Abiotic variables are, in general, more easily and less expensively obtained than biological observations, which is a key driver for surrogacy research. However, the suite of abiotic factors that exert control over the occurrence of species (its niche) is also a scientifically interesting aspect of ecology that provides important insights into a species evolution and biogeography. This chapter provides a review of surrogates used by case study authors and of the methods used to quantify relationships between variables.

Mapping of benthic habitats seldom considers biogeochemical variables or changes across time. We aimed to: (i) develop winter and summer benthic habitat maps for a sandy embayment; and (ii) compare the effectiveness of various maps for differentiating infauna. Patch-types (internally homogeneous areas of seafloor) were constructed using combinations of abiotic parameters, and are presented in sediment-based, biogeochemistry-based and combined sediment/biogeochemistry-based habitat maps. August and February surveys were undertaken in Jervis Bay, Australia, to collect samples for physical (%mud, sorting, %carbonate), biogeochemical (chlorophyll a, sulfur, sediment metabolism, bio-available elements) and infaunal analyses. Boosted Decision Tree and cokriging models generated spatially continuous data-layers. Habitat maps were made from classified layers using GIS overlays, and were interpreted from a biophysical-process perspective. Biogeochemistry and %mud varied spatially and temporally, even in visually homogeneous sediments. Species turnover across patch-types was important for diversity, and the utility of habitat maps for differentiating biological communities varied across months. Diversity patterns were broadly related to reactive carbon and redox which varied temporally. Inclusion of biogeochemical factors and time in habitat maps provides a better framework for differentiating species and interpreting biodiversity patterns than once-off studies based solely on sedimentology or video-analysis.

Geoscience Australia carried out marine surveys in Jervis Bay (NSW) in 2007, 2008 and 2009 (GA303, GA305, GA309, GA312) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments (for textural and biogeochemical analysis) and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wavegenerated currents. Data and samples were acquired using the Defence Science and Technology Organisation (DSTO) Research Vessel Kimbla. Bathymetric mapping, sampling and tide/wave measurement were concentrated in a 3x5 km survey grid (named Darling Road Grid, DRG) within the southern part of the Jervis Bay, incorporating the bay entrance. Additional sampling and stills photography plus bathymetric mapping along transits was undertaken at representative habitat types outside the DRG. This 126 sample data set comprises TCO2 flux and pool data for surface seabed sediments (~0 to 2 cm).