At the Australian Marine Sciences Association conference held in Canberra in July 2014, a group of scientists and managers engaged in a roundtable discussion to identify areas where linkages could be improved between researchers working on marine population connectivity and managers of marine areas. Population connectivity is the degree of demographic connectedness between populations, indicating the degree to which populations are linked through dispersal and recruitment of organisms, or through gene flow. Connectivity allows organisms and genes to move among different habitats, helping to ensure survival of species by providing increased habitat and reproduction options, and helping to maintain genetic variability. Although connectivity science was used as the focal point of the discussion, the issues discussed are applicable to other topics at the interface of science and management. Here we summarise the key themes and outcomes/recommendations from the discussion.

Although marine reserves are becoming increasingly important as anthropogenic impacts on the marine environment continue to increase, we have little baseline information for most marine environments. We use a species-level inventory compiled from three marine surveys to the Oceanic Shoals Commonwealth Marine Reserve (CMR) in northern Australia to address several questions relevant to marine management: 1) Are carbonate banks and other raised geomorphic features associated with biodiversity hotspots? 2) Are there environmental or biogeographic variables that can help explain local and regional differences in community structure? 3) How do sponge communities differ between individual raised geomorphic features? Approximately 750 sponge specimens were collected and assigned to 348 species, of which only 18% included taxonomically described species. Between the eastern and western CMR, there was no difference between sponge species richness or assemblages on raised geomorphic features. Within individual raised geomorphic features, sponge assemblages were significantly different, but species richness was not. There were no environmental factors related to sponge species richness, although sponge assemblages were weakly but significantly related to several environmental variables. These patterns of sponge diversity are considered in the context of marine reserve management in order to explore how such information may help support the future management of this region at multiple spatial scales.

Continental shelf margin habitats are increasingly being recognized worldwide for conservation and protection from human activities due to their biodiversity value. Yet, quantitative data on the biodiversity of the epibenthic taxa found on these continental shelf margins are scant. Consequently, this paper quantified the diversity of epibenthic taxa on an exposed- and sediment-inundated reef system located on the continental shelf margin off southeastern Australia as part of a program developing deep reef monitoring protocols. The reef system harbored a rich epibenthic taxa, with a total of 55 taxa identified from the images captured by an autonomous underwater vehicle. A Cnidaria/Bryzoa/Hydroid matix dominated the assemblages recorded. Taxa richness, diversity and evenness declined with distance from exposed reef ledge features, a characteristic geomorphic feature of this region. Patterns of the epibenthic assemblages were characterized by (1) taxonomic turnover at scales of 5 to 10's m from exposed reef ledges, (2) 30 % of epibenthic taxa were recorded only once (i.e. singletons), and (3) generally low levels of abundance of the component epibenthic taxa. This suggests that the assemblages in this region contain a considerable number of locally rare taxa, and potentially represent a high level of endemism. This study also highlights the importance of exposed reef ledge features in this region as they provide a refuge against sediment scouring and inundation in sediment-dominated ecosystems. Consequently, from a perspective of conservation planning for continental shelf habitats, protecting a single, or just a few, areas of reef are unlikely to accurately represent the geomorphic diversity of cross-shelf habitats and the epibenthic diversity that responds to this. Likewise, sampling needs to be adaptive, and stratified to incorporate known or suspected patterns relating to such variability. In this context, the data collected here provides a regional baseline dataset on the epibenthic taxa that shape the overall community structure for the Flinders Commonwealth Marine Reserve, and a guideline for sand-inundated cross-shelf reefs in general. Similar studies are now required for other known categories of cross-shelf reefs, including relict coastlines and complex block features more typical of igneous rock types.

As the oceans simultaneously warm and acidify, prospects for marine biota are of growing concern. In addition to these global change stressors, marine organisms are also exposed to many other anthropogenic stressors with likely interactive effects, including synergisms in which the combined effects of multiple stressors are greater than the sum of individual effects. Early life stages of marine organisms have been recognised as potentially vulnerable to the stressors associated with global change, but identifying patterns across studies, species and a range of response variables is challenging. In this study, we identify knowledge gaps in research on multiple abiotic stressors and early life stages (embryo to larvae), and we perform a meta-analysis to quantify stressor interactions on early life history stages of marine invertebrates, specifically between temperature, salinity and pH as these are the best studied. Temperature was the most common stressor (91% of studies), while the most common combination of stressors was temperature and salinity (66%), followed by temperature and pH (17.5%). All studies were conducted in the laboratory although four studies also undertook field experiments. Synergistic interactions (68% of individual tests) were more common than additive (16%) or antagonistic (16%) interactions. The meta-analysis yielded several key results: 1) Temperature and salinity synergistically interacted to negatively affect marine embryos and larvae, while temperature and pH antagonistically interact. 2) Embryos are more vulnerable than larvae to thermal and salinity stress but not to pH stress. 3) Survival is less likely to be affected than sub-lethal responses in stress treatments incorporating pH, but there is no discernible pattern in temperature, salinity, and temperature/salinity treatments. 4) Interaction types vary among stressors, phyla, ontogenetic stages, and biological responses. 5) Elevated temperature is generally not a greater stressor than ocean acidification and salinity, but this depends on ontogenetic stage and phylum 6) Ocean acidification is a greater stressor for calcifying than non-calcifying embryos and larvae. We use these results to identify organisms that may be particularly vulnerable or robust to stress associated with temperature, pH, and salinity. Although several clear patterns have emerged from this review and meta-analysis, the challenge now is to develop recommendations for stress ecology experiments in order to facilitate inter-study comparisons, as well as to translate these results to the field.

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.

Geoscience Australia's GEOMACS model was utilised to produce hindcast hourly time series of continental shelf (~20 - 300 m depth) bed shear stress (unit of measure: Pascal, Pa) on a 0.1 degree grid covering the period March 1997 to February 2008 (inclusive). The hindcast data represents the combined contribution to the bed shear stress by waves, tides, wind and densitydriven circulation. The geometric mean was calculated using the formula where is the total number of model observations of the bed shear stress . The geometric mean was used alongside the trimmed mean to provide a more robust representation of the bulk of the values than the arithmetic mean would have provided (Hughes & Harris 2008).

Geoscience Australia's GEOMACS model was utilised to produce hindcast hourly time series of continental shelf (~20 - 300 m depth) bed shear stress (unit of measure: Pascal, Pa) on a 0.1 degree grid covering the period March 1997 to February 2008 (inclusive). The hindcast data represents the combined contribution to the bed shear stress by waves, tides, wind and densitydriven circulation. Included in the parameters that represent the magnitude of the bulk of the data are the quartiles of the distribution; Q25, Q50 and Q75 (i.e. the values for which 25, 50 and 75 percent of the observations fall below). Q25, or the 0.25 Quartile of the Geomacs output, represents the values for which 25% of the observations fall below (Hughes & Harris 2008).

Understanding the distribution and abundance of sponges and their associated benthic habitats is of paramount importance for the establishment and monitoring of marine reserves. Benthic sleds or trawls can collect specimens for taxonomic and genetic research, but these sampling methods can be too qualititative for many ecological analyses and too destructive for monitoring purposes. Advances in the use of underwater videography and still imagery for biodiversity habitat mapping and modelling have been used within Geoscience Australia to extract data related to sponge biodiversity patterns across three regions. In the new Oceanic Shoals Commonwealth Marine Reserve, sponge morphologies were characterized from still images to locate areas in which biodiversity may be high due to habitat-forming taxa. In the Carnarvon Shelf abundance of a target sponge (Cinachyrella sp.) was quantified from video to investigate relationships between biology and sediment characteristics. Around Lord Howe Island, benthic habitats are being analysed to the national standard of classification using both video and still images. Importantly specialists within ecology, geophysics and spatial statistics work together to integrate biological and physical data to provide unique and meaningful maps of predicted distributions and habitat suitability for key ecological benthic habitats.

In November 2012, the Australian Government finalised a national network of Commonwealth Marine Reserves (CMR) covering 3.1 million km2 and representing the full range of large scale benthic habitats known to exist around mainland Australia. This network was designed using the best available regional-scale information, including maps of seabed geomorphic features and associated Key Ecological Features. To support the management objectives of the marine reserves, new site-specific information is required to improve our understanding of biodiversity patterns and ecosystem processes across a range of spatial scales. In this context, the Marine Biodiversity Hub (funded through the National Environmental Research Program) recently completed a collaborative 'voyage of discovery' to the Oceanic Shoals CMR in the Timor Sea. This area was chosen because it hosts globally significant levels of biodiversity (including endemic sponge and coral taxa), faces rapidly increasing pressures from human activities (offshore energy industry, fishing) yet is recognised as one of the most poorly known regions of Northern Australia. Undertaken in September 2012 on board RV Solander, the survey acquired biophysical data on the shallow seabed environments for targeted areas within the Oceanic Shoals CMR, with a focus on the carbonate banks that characterise this tropical shelf and are recognised as a Key Ecological Feature. Data collected included 500 km2 of high resolution (300 kHz) multibeam sonar bathymetry and acoustic backscatter across four grids, plus seabed sediment samples, underwater tow-video transects (~1 km length), pelagic and demersal baited underwater video, epifaunal and infaunal samples and water column profiles at pre-determined stations. Station locations were designed to provide a random but spatially balanced distribution of sample sites, with weighting toward the banks. This design also facilitated observations of patterns of benthic biodiversity at local to feature-scale and transitions associated with depth-gradients and exposure to tidal currents. Results reveal the banks are broadly circular to elliptical with steep sides, mantled by muddy sand and gravel with areas of hard ground. Rising to water depths of 50-70 m, the banks support benthic assemblages of sponges and corals (including hard corals at shallower sites) which in turn support other marine invertebrates. In strong contrast, the surrounding seabed is characterised by barren, mud-dominated sediments in 70-100 m water depth, although infaunal samples reveal diverse biological communities beneath the seafloor. While the bank assemblages are locally isolated, the potential exists for connectivity between shoals via tide-driven larval dispersal. Ongoing work is aimed at identifying species to determine overlap between bank communities, as well as modelling the sources, pathways and sinks for larvae as a proxy for understanding the physical processes controlling the patterns of biodiversity across the Oceanic Shoals CMR at multiple scales.

This resource contains geochemistry data for the Oceanic Shoals Commonwealth Marine Reserve (CMR) in the Timor Sea collected by Geoscience Australia during September and October 2012 on RV Solander (survey GA0339/SOL5650). This dataset comprises major and trace element concentrations in the upper 2 cm of seabed sediment. The Oceanic Shoals Commonwealth Marine Reserve survey was undertaken as an activity within the Australian Government's National Environmental Research Program Marine Biodiversity Hub and was the key component of Research Theme 4 - Regional Biodiversity Discovery to Support Marine Bioregional Plans. Hub partners involved in the survey included the Australian Institute of Marine Science, Geoscience Australia, the University of Western Australia, Museum Victoria and the Museum and Art Gallery of the Northern Territory. Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; sub-bottom acoustic profiles; physical samples of seabed sediments, infauna and epibenthic biota; towed underwater video and still camera observations of seabed habitats; baited video observations of demersal and pelagic fish, and; oceanographic measurements of the water column from CTD (conductivity, temperature, depth) casts and from deployment of sea surface drifters. Further information on the survey is available in the post-survey report published as Geoscience Australia Record 2013/38: Nichol, S.L., Howard, F.J.F., Kool, J., Stowar, M., Bouchet, P., Radke, L., Siwabessy, J., Przeslawski, R., Picard, K., Alvarez de Glasby, B., Colquhoun, J., Letessier, T. & Heyward, A. 2013. Oceanic Shoals Commonwealth Marine Reserve (Timor Sea) Biodiversity Survey: GA0339/SOL5650 - Post Survey Report. Record 2013/38. Geoscience Australia: Canberra. (GEOCAT #76658).