The threatened status of shellfish reefs has been well established globally (e.g Beck et al 2011) however the ecological consequences of these losses is still largely unknown. In Australia, shellfish reefs are one of the most imperilled marine habitat types (Gillies et al 2018), due to historical overharvest and widespread eutrophication of coastal waters through the use of fertilizers, livestock and human waste. Marine bivalves are important ecosystem engineers providing habitat, shelter and a food source for other species in benthic soft-sediment environments. In addition, filter-feeding bivalves link benthic and pelagic components of ecosystems through filtration and excretion. Through their filter feeding, they produce large amounts of faeces (digested seston) and pseudofaeces (rejected particles bound up in mucus) which are deposited on the benthos. This process brings energy and nutrients from the pelagic system to the benthic system (bentho-pelagic coupling). The removal of large quantities of seston can serve an important ecosystem function by improving water quality and clarity. The filtration of water performed by bivalves has been demonstrated to reduce water turbidity, improving light penetration and thereby enhancing growing conditions for seagrasses (Wall et al 2008). In systems where healthy populations of bivalves remain, they can filter a volume equivalent or larger than the entire estuary volume within the residence time of the water (zu Ermgassen et al 2013). While such densities of oysters are rare today, this highlights the critical ecosystem services that are lost when oyster reefs decline. Furthermore, it demonstrates the potential functions that can be regained through oyster reef restoration. Given the increasing awareness of the decline of these ecosystems, interest in restoration efforts to restore critical ecosystem functions has been growing. However, conservation and restoration decision making is underpinned by reliable quantification of relevant ecosystem services (zu Ermgassen et al 2016). For example, there are plans to restore some of the natural oyster reefs of Sydney Rock Oyster (Saccostrea glomerata) in Port Stephens, New South Wales. One of the main drivers motivating this restoration project is restoring lost ecosystem services. The filtration rates of Australian oysters has been demonstrated in aquarium studies using filtered water augmented with algae, yet little is known about filtration and biodeposition rates of oysters using raw seawater. In this study, we provide the first evaluation of the filtration and biodeposition rate of four species of bivalves using raw seawater, providing a proxy for natural biodeposition rates. As such, this study provides a first indication of the filtration/nutrient cycling function that may be restored following oyster restoration efforts.

Australia is home to a quarter of the world’s cartilaginous fishes (Class Chondrichthyes) with 328 species consisting of 182 sharks, 132 rays, and 14 chimaeras. Australia’s first Shark Action Plan aims to provide a comprehensive and consistent review of the extinction risk of all cartilaginous fishes (hereafter ‘sharks’) occurring in Australian waters, to provide a benchmark from which changes in population and risk can be measured, and to help guide management for their conservation. This Action Plan also serves to raise the profile of their diversity and conservation needs. This volume includes a taxa profile for each of the 328 species occurring in Australian marine and inland waters, including external territories. Each species’ extinction risk was assessed by applying the IUCN Red List Categories and Criteria at the national level. Assessments of extinction risk consider all available information on a species’ taxonomy, distribution, population status, habitat and ecology, major threats, use and trade, and conservation measures. The IUCN Red List Categories and Criteria utilise a series of thresholds to evaluate extinction risk based on population size reduction, geographic range, population size, or the probability of extinction. Species were assessed against the five Red List criteria; to qualify for one of the three threatened categories (Critically Endangered, Endangered, or Vulnerable), a species had to meet a quantitative threshold for that category in any of the five criteria. The overall status of sharks in Australia is characterised by a relatively low level of extinction risk and a high level of secure species. Of the 328 species, 12% are threatened (39 species: 22 sharks, 17 rays; no chimaeras are threatened); 10% are Near Threatened (32 species: 18 sharks, 13 rays, 1 chimaera); 70% are Least Concern (231 species: 123 sharks, 95 rays, 13 chimaeras); and, 8% are Data Deficient (26 species: 19 sharks, 7 rays, no chimaeras are Data Deficient). No species are Extinct or Extinct in the Wild. Each taxa profile specifies two sets of actions for a species: actions to address knowledge gaps, and actions to maintain, secure, and if necessary, recover the population. To improve the ability to accurately assess the status of species, and ultimately, better conserve and manage them, all species treated in this Action Plan require some knowledge gaps be filled. Knowledge gaps are divided into five themes, each of which improves the information base from which to assess status: taxonomy, distribution, population trend, life history, and connectivity. Conservation actions are provided for each species, regardless of the status assigned them in this Action Plan. While threatened species require immediate action to conserve, manage, and recover their populations, Least Concern species also require action to maintain their secure status. Data Deficient species require action to understand various aspects of their population, but since an assessment as Data Deficient acknowledges the possibility that future research may show that a threatened classification is appropriate, action is also needed to minimise or mitigate threats until such time as more information is available to show that the species is not threatened. Finally, an overarching recommendation is provided for each threatened species. This includes the recommendation that five species be considered for listing on the Environment Protection and Biodiversity Conservation Act (EPBC Act), three species be considered for up-listing, and two species be considered for down-listing. An additional 12 threatened species have been identified as priorities for data collection where further data are required to strengthen the evidence-base underlying their status determinations. These species are priorities for research and monitoring to provide data to support inferred or suspected population reductions or continuing declines identified in the Action Plan. The implementation of the recommendations and actions in this Action Plan will require an ongoing and enhanced investment in science and management which will help secure the future of Australia’s sharks, rays, and chimaeras.

Carbon and nitrogen isotope data for J. edwardsii lobsters from eight sites in SE Australia.

Google Earth KMZ files of hammerhead sharks tagged with Wildlife Computers miniPAT archival tags and SPOT6 tags. Files of animals tagged with MiniPAT tags include an MELE polygon, which is the 'Maximum extent of location estimates', that is, a polygon enclosing all position estimates at the maximum error level (100 km). Collectively, movements are restricted within state waters with no hammerheads moving across state or International boundaries.

Policy and decision makers often seek guidance as to the benefits of conservation and repair of coastal seascapes, to justify and underpin any potential investments. Much is already known about the broad habitat and nursery values of seascapes among the science community, but there is also a need for estimation of clear and unambiguous market-based benefits that may arise from investment in repair. Recognising that this economic knowledge is imperfect for Australian seascapes, three case studies spanning tropical, subtropical and temperate environments explored the benefits in question. The case studies focus on saltmarsh habitats in particular, which have received very little investment in repair despite subtropical and temperate coastal saltmarsh listed as vulnerable ecological community under Australian Federal legislation. A subset of economically important species and conservative judgments were used to characterise the minimum potential economic benefit. For each of the case studies the conclusion was that while the biological information will remain imperfect, the business case for investment in the repair and conservation of coastal seascapes is compelling. We outline priorities for further research to make the business case more tangible to policy makers, stakeholders and the general public.

Estimates of the value of habitats can provide an objective basis for the prioritisation of conservation and restoration actions. Bivalve habitats, three-dimensional structures made of high-densities of bivales (most often oysters or mussels), their shells and other organisms, used to be a dominant habitat found in temperate and subtropical coastal waters. These habitats, provide a suite of ecosystem services such as habitat provision and food supply for many species, substrate stabilisation and shoreline protection, and water quaility improvements through their filter feeding. Bivalve habitat restoration is increasingly seen as an opportunity to return lost ecosystem services. In Australia, there is growing interest in bivalve habitat restoration, but there is a knowledge gap in regards to the services they provide. Here, we determined the habitat value of a historically dominant oyster species in Australia, Saccostrea glomerata. At remnant soft-sediment oyster reefs at four locations we estimated density, biomass, productivity and composition of mobile macroinvertebrate communities and compared these with adjacent ‘bare’ soft sediments, which typically replace ecologically extinct oyster reefs. The oyster reefs had a distinct assemblage of macroinvertebrates, with 30% higher densities, 5 times the biomass and almost 5 times the productivity of adjacent bare sediments. Infauna macroinvertebrate productivity was more than twice as high below oyster reefs, suggesting these reefs facilitate infaunal productivity. Crustaceans, an important food source for small fishes, were 13 times more productive on oyster reefs compared to adjacent bare sediments. These results demonstrate that oyster reefs provide an important habitat for macroinvertebrates and that restoration efforts are likely to provide significant returns in enhanced productivity.

This record relates to outputs from a series of socio-economic surveys conducted nationally to benchmark awareness and perceptions towards the Australian Marine Parks. This includes a general public survey, a boat ramp survey (focussed on boat-based recreational users), a targeted survey (focussed on members of fishing, boating and yacht clubs) and a charter operator survey (focussed on fishing and eco-charter operators). All surveys were conducted across 2019-2020. Raw data could not be made available. Aggregated survey data is supplied as summary plots in the final report: https://www.nespmarine.edu.au/document/social-and-economic-benchmarks-australian-marine-parks