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Reefs of the flat oyster (Ostrea angasi) were once common along the southern coasts of Australia. Historical and current literature relating to O. angasi was used to identify bays and estuaries where this species once existed. In many estuaries of Western Australia, current populations are significantly lower than historical levels, including in Princess Royal Harbour and Oyster Harbour, near Albany. The main causes of the declines included overfishing, combined with the use of destructive fishing methods, such as dredging. Other factors, such as sedimentation, increased nutrient input and loss of seagrass, may have contributed to the loss of oyster reefs, and may have inhibited effective recovery. The possible impact of the protozoan pathogen Bonamia exitiosa is uncertain, although it is known to have severely affected flat oyster populations in other parts of the world. The fact that O. angasi reefs in Oyster Harbour did not recover after the fishery ceased suggests that restoration activities, aimed at restarting the ecosystem services that the oyster reefs once provided, should be undertaken. This paper suggests that the historical presence of O. angasi could be an effective starting point for prioritising potential restoration sites and details the prioritisation protocol that was used in recent restoration activities.

Achieving a sustainable socioecological future now requires large-scale environmental repair across legislative borders. Yet, enabling large-scale conservation is complicated by policy-making processes that are disconnected from socioeconomic interests, multiple sources of knowledge, and differing applications of policy. We considered how a multidisciplinary approach to marine habitat restoration generated the scientific evidence base, community support, and funding needed to begin the restoration of a forgotten, functionally extinct shellfish reef ecosystem. The key actors came together as a multidisciplinary community of researchers, conservation practitioners, recreational fisher communities, and government bodies that collaborated across sectors to rediscover Australia's lost shellfish reefs and communicate the value of its restoration. Actions undertaken to build a case for large-scale marine restoration included synthesizing current knowledge on Australian shellfish reefs and their historical decline, using this history to tell a compelling story to spark public and political interest, integrating restoration into government policy, and rallying local support through community engagement. Clearly articulating the social, economic, and environmental business case for restoration led to state and national funding for reef restoration to meet diverse sustainability goals (e.g., enhanced biodiversity and fisheries productivity) and socioeconomic goals (e.g., job creation and recreational opportunities). A key lesson learned was the importance of aligning project goals with public and industry interests so that projects could address multiple political obligations. This process culminated in Australia's largest marine restoration initiative and shows that solutions for large-scale ecosystem repair can rapidly occur when socially valued science acts on political opportunities.Transformación de un Ecosistema Arrecifal Perdido en un Programa Nacional de Restauración Resumen Actualmente se requiere una reparación ambiental a gran escala que atraviese fronteras legislativas para lograr un futuro socio-ecológico sustentable. Aun así, habilitar la conservación a gran escala es complicado debido a los procesos de elaboración de políticas que están desconectadas de los intereses socio-económicos, las múltiples fuentes de conocimiento y las diferentes aplicaciones de las políticas. Consideramos cómo una estrategia multidisciplinaria para la restauración de hábitats marinos generó una base de evidencia científica, apoyo comunitario y el financiamiento necesario para así iniciar la restauración de un ecosistema arrecifal de conchas funcionalmente extinto. Los actores clave formaron una comunidad multidisciplinaria de investigadores, practicantes de la conservación, comunidades de pescadores recreativos y órganos gubernamentales que colaboró con varios sectores para redescubrir los arrecifes perdidos de Australia y comunicó el valor de su restauración. Las acciones realizadas para armar el caso para la restauración marina a gran escala incluyeron la síntesis del conocimiento actual sobre los arrecifes de conchas en Australia y su declinación histórica, el uso de esta historia para contar una narración convincente que active el interés público y político, la integración de la restauración a la política gubernamental y la movilización del apoyo local por medio de la participación comunitaria. Claramente, la articulación del caso del negocio social, económico y ambiental para la restauración llevó al financiamiento estatal y nacional para la restauración arrecifal a cumplir diversos objetivos socio-económicos (p. ej.: creación de empleos, oportunidades recreativas) y de restauración (p. ej.: una productividad realzada de la biodiversidad y las pesquerías). Una lección clave que aprendimos fue lo importante que es alinear los objetivos del proyecto con los intereses públicos y de la industria, de tal manera que los proyectos aborden las múltiples obligaciones políticas. Este proceso culminó con la iniciativa de restauración marina más grande en Australia y demuestra que las soluciones para la reparación de los ecosistemas a gran escala pueden ocurrir rápidamente cuando la ciencia con valor social actúa sobre las oportunidades políticas.

The United Nations General Assembly calls for ecosystem restoration to be a primary intervention strategy used to counter the continued loss of natural habitats worldwide, while supporting human health and wellbeing globally. Restoration of coastal marine ecosystems is perceived by many to be expensive and prone to failure, in part explaining its low rates of implementation compared with terrestrial ecosystems. Yet, marine ecosystem restoration is a relatively new field, and we argue that assessments of its potential to answer this call should not rely on typical outcomes, but also to learn from successful outliers. Here, we review successful restoration efforts across a suite of metrics in coastal marine systems to highlight 'bright spots'. We find that, similar to terrestrial systems, restoration interventions can be effective over large spatial expanses (1,000s-100,000s ha), persist for decades, rapidly expand in size, be cost-effective, and generate social and economic benefits. These bright spots clearly demonstrate restoration of coastal marine systems can be used as a nature-based solution to improve biodiversity and support human health and wellbeing. Examining coastal marine restoration through a historical lens shows that it has developed over a shorter period than restoration in terrestrial systems, partially explaining lower efficiencies. Given these bright spots and the relative immaturity of coastal marine ecosystem restoration, it is likely to advance rapidly over the coming decades and become a common intervention strategy that can reverse marine degradation, contribute to local economies, and improve human wellbeing at a scale relevant to addressing global threats.

Shellfish reefs are one of the most depleted marine ecosystems in the world, and there is considerable interest and efforts to restore the ecosystems. When degraded reefs require the addition of new substrate to support oyster re‐establishment, recycled shells can be used to rebuild new reef bases. Shell recycling as a means of procuring shells was first introduced in Australia by The Nature Conservancy in 2015, through the establishment of the ‘Shuck Don’t Chuck’ Shell Recycling Project in Victoria. The recycling project was first piloted in the regional city of Geelong with the aim of providing sufficient quantity of clean, recycled shell to support reef base construction for shellfish reef restoration in Port Phillip Bay. The project has subsequently expanded into markets and restaurants in Melbourne. Community involvement and restoration promotion are important secondary outcomes of the programme. We provide lessons from our experience to date and a step‐by‐step guide of how to establish a shell recycling project from initial pilot and trial stages to a full programme. These steps include the following: (i) recruitment of shell recycling partners, (ii) transport and logistics, (iii) shell storage sites, (iv) biosecurity and curing protocols, (v) hatchery use, (vi) reef deployment, and (vii) community engagement. Shell recycling is an effective way to not only source substrate for restoring shellfish reefs, but also to reduce the amount of waste going to landfill and should be considered as part of any shellfish reef restoration project which utilises shell products.

Recognizing the historical loss of habitats and the value and opportunities for their recovery is essential for mobilizing habitat restoration as a solution for managing ecosystem function. Just 200 years ago, Sydney rock oysters (Saccostrea glomerata) formed extensive reef ecosystems along Australia's temperate east coast, but a century of intensive harvest and coastal change now confines S. glomerata to encrusting the hard-intertidal surfaces of sheltered coastal waters. Despite the lack of natural reef recovery, there appears enormous potential for the restoration of intertidal S. glomerata ecosystems across Australia's east coast, with large anticipated benefits to water quality, shoreline protection, and coastal productivity. Yet, no subtidal reefs remain and the potential for subtidal restoration is a critical knowledge gap. Here, we synthesize historical, ecological, and aquaculture literature to describe a reference system for the traits of S. glomerata reefs to inform restoration targets, and outline the barriers to, and opportunities and methods for, their restoration. These reefs support extremely biodiverse and productive communities and can ameliorate the environmental stress experienced by associated communities. Rock oyster restoration, therefore, provides an ecosystem-based strategy for assisting the adaptation of marine biodiversity to a changing climate and intensive human encroachment. Though an estimated 92% of S. glomerata ecosystems are lost, there remains great potential to restore these valuable and resilient ecosystems.

This article considers how “rolling covenants” (i.e., covenants on land title that can operate in a “rolling” geographic area to keep pace with sea‐level rise) can be used to permit productive use of land in the short term, while ensuring land use can shift over time to allow for coastal ecosystem migration in the medium to long term. We use Australia as a case study, and through analysis of legislation and a series of semistructured interviews, we demonstrate how land title‐based covenants can be used to give legal effect to “rolling covenant” arrangements where land is subject to existing use and occupation. We then consider practical issues associated with drafting a rolling covenant arrangement, including an analysis of the types of events or scenarios that could be used as a basis for land use changing (e.g., projected sea‐level rise, actual ecosystem migration), and the advantages and disadvantages of each. We conclude that rolling covenants are a viable option for land management in the coastal zone, especially in circumstances where funding sources are available to incentivize uptake. Rolling covenants may provide opportunities for coastal wetlands to be maintained and even enhanced in cover, thereby delivering important ecosystem services (e.g., blue carbon) into the future.

Important intertidal coastal habitats – particularly mangroves, saltmarshes and beaches – are particularly threatened by the impacts of climate change-driven sea-level rise. Coastal development and coastal armoring present physical barriers for the natural inland migration of coastal habitats, and changes in hydrological connectivity reduce sediment inputs and the potential for vertical accretion. We identify mechanisms and enabling conditions to accommodate migration of these habitats in Australia and the United States. A range of financial, policy, planning and on-the-ground management tools in both countries that already exist, often for a different purpose, can be implemented or modified to also enable inland habitat migration. Awareness of approaches/solutions can assist land managers and policy makers to accommodate migration of habitats as a necessary component of coastal management in an era of increasing rates of sea level rise.

As the world's population continues to grow, the way in which ocean industries interact with ecosystems will be key to supporting the longevity of food and social securities. Aquaculture is crucial to the future supply of seafood, but challenges associated with negative impacts could impede increased production, especially production that is efficient and safe for the environment. Using the typology established by The Economics of Ecosystems and Biodiversity Initiative, we describe how marine aquaculture could be influential in supporting ecosystem services beyond solely the production of goods, through provisioning services, regulating services, habitat or supporting services, and cultural services. The provision of these services will vary, depending on functional traits of culture species, biotic and abiotic characteristics of the surrounding environment, farm design, and operational standards. Increasing recognition, understanding, and accounting of ecosystem service provision by mariculture through innovative policies, financing, and certification schemes may incentivize active delivery of benefits and may enable effects at a greater scale.

Reef ecosystems all over the world are in decline and managers urgently need information that can assess management interventions and set national conservation targets. We assess the conservation status and risk of ecosystem collapse for the Oyster Reef Ecosystem of Southern and Eastern Australia, which comprises two community sub-types established by Saccostrea glomerata (Sydney rock oyster) and Ostrea angasi (Australian flat oyster), consistent with the IUCN Red List of Ecosystems risk assessment process. We established: (i) key aspects of the ecosystem including: ecological description, biological characteristics, condition and collapse thresholds, natural and threatening processes; (ii) previous and current extent of occurrence and current area of occupancy; and (iii) its likelihood of collapse within the next 50–100 years. The most severe risk rating occurred for Criterion A: Reduction in Extent (since 1750) and Criterion D: Disruption of biotic processes (since 1750), although assessment varied from Least Concern to Critically Endangered amongst the four criteria assessed. Our overall assessment ranks the risk of collapse for the ecosystem (including both community sub-types) as Critically Endangered with a high degree of confidence. Our results suggest the need for rapid intervention to protect remaining reefs and undertake restoration at suitable sites. Several restoration projects have already demonstrated this is feasible, and Australia is well equipped with government policies and regulatory mechanisms to support the future conservation and recovery of temperate oyster ecosystems.

Widespread global declines in shellfish reefs (ecosystem‐forming bivalves such as oysters and mussels) have led to growing interest in their restoration and protection. With restoration projects now occurring on four continents and in at least seven countries, global restoration guidelines for these ecosystems have been developed based on experience over the past two decades. The following key elements of the guidelines are outlined: (a) the case for shellfish reef restoration and securing financial resources; (b) planning, feasibility, and goal setting; (c) biosecurity and permitting; (d) restoration in practice; (e) scaling up from pilot to larger scale restoration, (f) monitoring, (g) restoration beyond oyster reefs (specifically mussels), and (h) successful communication for shellfish reef restoration projects.

[Excerpt] Best known as a "love them or hate them" luxury food, or for their pearls, oysters are also ecosystem engineers, forming vast oyster reefs. Oyster reefs provide habitat for a myriad of species, and support fisheries, improve water quality and provide coastal protection. These services are estimated to be worth US$5,500–$99,000 per hectare per year (Grabowski et al. 2012). Globally, oyster reefs have declined by 85% through destructive overfishing, coastal development, pollution, and introduced competitors, predators and diseases (Beck et al. 2011). Active restoration is becoming an increasingly popular tool to bring back lost oyster reefs and the ecosystem services they provide (Fitzsimons et al. 2019). However, restoration is not always successful, and knowledge about how reefs naturally form and function is vital to improve restoration success. Oyster larvae only settle on hard substrates. Reefs proliferate because oyster shells provide a settlement surface, and oysters provide chemical and sound cues that facilitate larval settlement (Lillis et al. 2013). However, these reefs often form on intertidal sand and mud banks. This raises the question, how do oyster reefs form on mud banks in the absence of hard surfaces?

Oysters, mussels and other shellfish are culturally and economically important resources for coastal communities globally. In Australia, Aboriginal and Torres Strait Islander peoples have engaged in the harvest, consumption, ecological management and trade of shellfish and shellfish products for millennia (Bailey 1975; Beck et al. 2011; Alleway & Connell 2015). Shellfish ecosystems have been severely reduced in Australia since European settlement through overharvest using destructive fishing practices, pollution and disease (reviewed in Gillies et al. 2018, 2015). There is growing interest in the restoration of shellfish ecosystems in Australia to bring back a vastly reduced natural ecosystem, and the ecosystem services they provide such as providing habitat for other species, water filtration and shoreline protection (Gillies et al. 2015).

Globally, coastal habitat restoration is growing in recognition as a viable management tool to repair and reinstate valuable coastal habitats and species, such as mangrove and macroalgae forests, salt marshes, seagrass meadows, shellfish and coral reefs (Aronson & Alexander (2013), Restoration Ecology, 293; Anthony et al. (2017) Nature Ecology and Evolution, 1420; TNC (2017) Caribbean: A revolution to save coral reefs in the Caribbean and beyond). In Australia, there is increasing interest and investment in coastal restoration and habitat conservation, particularly with respect to growing national concerns around habitat loss, coastal inundation and erosion, loss of fisheries and climate change (Maggini et al. (2013) Protecting and restoring habitat to help Australia's threatened species adapt to climate change; GBRMPA (2017) Reef summit sets new course of action for the Great Barrier Reef). This has led to new community of practices being formed for shellfish reef restoration (Shellfish Reef Restoration Network shellfishrestoration.org.au), seagrass restoration (Seagrass Restoration Network seagrassrestoration.net), and saltmarsh and mangrove (Saltmarsh and Mangrove Network, amsn.net.au) conservation. However, despite this interest, there has been no national coordination, network or society with coastal restoration as a primary focus. The inaugural Australian Coastal Restoration Symposium brought together 60 Australian restoration practitioners, researchers and managers at James Cook University, Townsville for three days from the 31st of August 2017. The symposium goals were to enhance collaboration and national coordination amongst coastal restoration projects and practitioners, as well as to connect researchers and practitioners working in the restoration space with one another. Three international keynote speakers shared their experiences and advice. Delegates were enthusiastic about continuing to meet at future symposiu, meetings and workshops, and noted the value of being able to connect, share project experiences and learnings, and collaborate. The Australian Coastal Restoration Network has been formed with the goal of meeting annually to continue to share knowledge and improve collaboration. View a video about the symposium by following this link – https://www.youtube.com/watch?v=lukSpo3mM-4

Three-dimensional reefs and beds created predominately by the native Angasi Oyster or Flat Oyster (Ostrea angasi) were once common across its range in Australia's southern coastal waters but were lost during the mid-late 1800s and early 1900s due to a combination of destructive fishing practices, overfishing and changes to estuarine conditions. Despite the continued presence of low densities of individuals and cessation of commercial fishing, reefs structures and their associated communities have shown little signs of natural recovery. Since 2014, a range of oyster reef restoration projects have commenced in Australia, guided by international restoration protocols that prioritise the re-establishment of the keystone species on artificial stable substrates placed in locations where natural oyster reefs have previously existed. These projects invariably need clear and realistic goals and objectives for restoration, which are aided by the use of a reference ecosystem as a model or target, for the local oyster reef ecosystem being restored, yet few reference sites exist. Reefs, established by Angasi, are absent from much or all of its geographical distribution, and the ecosystem has been poorly studied to date; hence, the application of restoration target ecosystems will largely depend on deriving a model based on historical descriptions and observation of what remains. Here, we develop an interim reference model to help set restoration objectives and recommended procedural framework for Angasi reef restoration based on available knowledge of the ecology, biology and aquaculture of the keystone species. We use the Port Phillip Bay oyster reef restoration project as a case study for using the reference model to guide interventions and evaluate the progress of recovery.

Bivalve habitats have, until recent times, been generally overlooked as an important estuary habitat type. Historically, complex, three-dimensional habitats made up of dense aggregations of bivalves, their shells, associated species, and accumulated sediments were a dominant habitat type in temperate and subtropical estuaries around the world (Stenzel, 1971). These habitats were generally engineered by oyster (generally referred to as reefs) or mussel (generally referred to as beds) species. Until recent times these habitats were primarily managed as an important fisheries resource. Their historical extent and importance are difficult to estimate because bivalve habitats were often decimated before fisheries records were collected systematically, and there may be no remaining visible functioning bivalve habitats. Through the process of historical amnesia, or shifting baselines, successive generations of local people, and managers have grown accustomed to the new norm and have forgotten about the former abundant bivalve habitats.

Australia’s developed coasts are a heavily competed space, subject to urban, industrial and agricultural development. A diversity of habitats, such as mangroves, saltmarshes and seagrasses, comprise Australia’s coastal seascape and provide numerous benefits including fish productivity, carbon sequestration, nutrient cycling, coastal protection and recreation. Decision makers need to be able to weigh up the relative costs and benefits of coastal development, protection or repair and to do this they need robust, accessible and defensible data on the ecological function and economic value of Australia’s coastal seascapes. We reviewed the published literature, with a focus on saltmarsh as a vulnerable ecological community, to determine the availability of information on key ecological functions that could inform ecosystem service valuation. None of the publications we reviewed quantified nutrient cycling, coastal protection or recreation functions. Only 13 publications presented quantitative information on carbon sequestration and fish productivity. These were limited geographically, with the majority of studies on sub-tropical and temperate saltmarsh communities between south-east Queensland and Victoria. This demonstrates a lack of quantitative information needed to substantiate and communicate the value of Australia’s saltmarshes in different locations, scales and contexts. Research should focus on addressing these knowledge gaps and communicating evidence in a relevant form and context for decision-making. We discuss four principles for research funding organisations and researchers to consider when prioritising and undertaking research on key ecological functions of Australia’s saltmarshes, and coastal seascapes more broadly, to support sustainable coastal development, protection and repair for long-term economic and community benefit.

Tidal wetlands are experiencing climate change driven shifts in their community composition, distribution, and functions. Mangroves have expanded into saltmarshes where their ranges overlap on five continents. Yet questions remain about the spatial variability of climate change drivers and subsequent local ecological feedbacks on these distributional shifts. Along the southernmost range of mangroves, we studied shifts between Avicennia marina and threatened saltmarsh communities. We used semi-automated object based image analysis to classify wetlands in aerial imagery from 1970 to 2017. Saltmarsh coverage decreased at the expense of mangrove encroachment. Landward migration of saltmarsh was negligible. Unlike other mangrove-saltmarsh ecotone studies, neither changes in seasonal extreme temperatures nor sea level rise were associated with the observed transitions. Rather, mangrove encroachment correlated with increasing annual maximum temperature and was more extensive at sites with lower mean elevations, shorter mean distances to earliest known mangrove-saltmarsh boundary, and higher densities of tidal creeks. Accounting for local variation in mangrove encroachment is informative for managing the provision of desirable ecosystem services. As climate change impacts the southernmost mangrove-saltmarsh ecotone, areas with higher mean elevations and fewer tidal creeks could be prioritized to mitigate the loss of saltmarsh.

Oyster reef ecosystems used to form significant components of many temperate and subtropical inshore coastal systems but have suffered declines globally, with a concurrent loss of services. The early timing of many of these changes makes it difficult to determine restoration targets which consider interdecadal timeframes, community values and shifted baselines. On the Australian continent, however, the transition from Indigenous (Aboriginal) to Westernized resource use and management occurred relatively recently, allowing us to map social-ecological changes in detail. In this study, we reconstruct the transformations in the Sydney rock oyster (Saccostrea glomerata) wild commercial industry of central and southeast Queensland, and by extension its reef ecosystems, as well as the changing societal and cultural values related to the presence and use of the rock oyster through time. By integrating data from the archaeological, anthropological and fisheries literature, government and media accounts, we explore these transformations over the last two centuries. Before the 1870s, there was a relative equilibrium. Aboriginal peoples featured as sole traders to Europeans, supplying oysters and becoming a substantial component of the industry's labour pool. Effectively, Australia's commercial oyster industry arose from Aboriginal-European trade. During this initial phase, there was still a relative abundance of wild oyster, with subtidal oyster reef structures present in regions where oysters are today absent or scarce. By contrast, these reefs declined by the late 19th century, despite production of oysters increasing due to continued large-scale oyster recruitment and the expansion of oyster cultivation in intertidal areas. Production peaked in 1891, with successive peaks observed in regions further north. During the 1890s, flood events coupled with land-use changes introduced large quantities of silt into the system, which likely facilitated an increase in oyster pests and diseases, ultimately decreasing the carrying capacity of the system. Today oyster production in this region is less than one-tenth of historical peak production. Many cultural heritage components have also been lost. Indigenous management is now very minor due to the massive decimation of Aboriginal populations and their respective practices. Yet, we found strong cultural attachment to midden remains and oyster production continues within Indigenous communities, with considerable broader community support. This study highlights the value of conducting thorough analysis of early media accounts as a means for reconstructing historical resource decline and management. It further demonstrates the application of historical information and context for contemporary management, protection and restoration of much-altered coastal social-ecological systems.

Oyster reef restoration is a growing field in Australia, yet formal descriptions of associated biological communities for reefs created by native flat oysters (Ostrea angasi) do not currently exist. Native flat oysters once formed extensive and complex three-dimensional habitats in bays and estuaries across southern Australia until indiscriminate fishing, sedimentation and disease led to their near disappearance. To determine the diversity and abundance on naturally occurring oyster reefs, we sampled four sites on the last known naturally occurring oyster reef ecosystem, which resides in north-eastern Tasmania, and compared them to the surrounding soft sediment regions. Assemblages were related to environmental variables to determine whether consistent patterns were present. Oyster reef sites contained three times the faunal abundance of the surrounding soft sediment regions. Abundance among echinoderms, arthropods, molluscs and fish was much elevated, whereas annelids showed similar levels of abundance but differed in terms of species composition. These results show that oyster reefs do support abundant and diverse assemblages, emphasising the probable loss of community-level biodiversity associated with their historical decline around southern Australia.

Estimates of the ecological and economic value of ecosystems can provide important information for the prioritisation of conservation and restoration actions. Oyster reefs that were once common in temperate coastal waters have now been largely degraded or lost. Oyster reefs provide a suite of ecological services, including habitat and a food supply for a range of other species. In Australia, there is growing interest in oyster reef restoration, but there are knowledge gaps with regard to their structure and habitat value. Here, we describe the structure of eight remnant Sydney rock oyster (Saccostrea glomerata) reefs and estimate the density, biomass, productivity and composition of mobile macroinvertebrate and infaunal communities associated with them. The oyster reefs had a distinct assemblage of macroinvertebrates, with fivefold higher density of larger (≥2mm) macroinvertebrates, fivefold higher biomass and almost fivefold higher productivity, than that of adjacent bare sediments. The productivity of infaunal communities was twice as high under oyster reefs than in adjacent bare sediments. Therefore, S. glomerata reef restoration is likely to provide important habitat for macroinvertebrate communities and boost local secondary production.

Rottnest Island, Western Australia, receives >500,000 visitors y −1 , who are mainly attracted by the Island’s natural values. Marine debris is a threat to both these natural values and to Island wildlife, and is consequently an important issue for managers. Engaging with volunteers, we quantified marine debris at 16 beach sites around the Island. The highest loads occurred on the SW coast and primarily comprised items originating from fishing activities. Sites on the NE coast, where >95% of the Island’s accommodation is located, supported the highest abundance of items deposited in situ (e.g. bottles and cigarette butts). We conclude that marine debris management may require a range of strategies to address the different primary sources. Raising awareness through education and intervention may be highly effective at popular beaches on the NE coast, but broader liaison with commercial and recreational fishers will be necessary to address the issue at the Island scale.

Shallow-water benthic communities throughout coastal Antarctica share many spe- cies and are governed by similar physico-oceanographic processes. This suggests community structure and function may be similar among communities despite being geographically sepa- rated by up to 15 degrees of latitude and 18 000 km of coastline. To test this theory, we developed a food web model using stable isotopes (δ 13 C, δ 15 N) for the high-latitude Vestfold Hills shallow- water benthic community and compared it to the isotopic food web model developed for the Wind- mill Islands, located over 1000 km away. For the Vestfold Hills food web, carbon sources were generally well separated by δ 13 C, and lower-order consumers could be grouped according to their feeding guild and main dietary sources as determined by δ 13 C and δ 15 N. Higher-order consumers occupied the full range of δ 13 C ratios and had similar δ 15 N values, although predators were weakly, but significantly, enriched in δ 15 N compared to scavenger/predators and omnivores. When comparing with the Windmill Islands food web, we found similar δ 13 C ratios for several co- occurring carbon sources and consumers, whilst the δ 15 N ratios in consumers from the Vestfold Hills were consistently enriched compared to those from the Windmill Islands by 1 to 2‰. The rel- ative positions of feeding guilds on the δ 13 C and δ 15 N planes were similar for both food webs. These results suggest there is considerable merit in developing a representative food web model for Antarctic shallow-water communities. Such a model would provide a trophic benchmark against which modification in these communities brought about by climate change or other human impacts could be compared.

The involvement of non-professionals in scientific research and environmental monitoring, termed Citizen Science (CS), has now become a mainstream approach for collecting data on earth processes, ecosystems and biodiversity. This chapter examines how CS might contribute to ongoing efforts in biodiversity monitoring, enhancing observation and recording of key species and systems in a standardised manner, thereby supporting data relevant to the Essential Biodiversity Variables (EBVs), as well as reaching key constituencies who would benefit Biodiversity Observation Networks (BONs). The design of successful monitoring or observation networks that rely on citizen observers requires a careful balancing of the two primary user groups, namely data users and data contributors (i.e., citizen scientists). To this end, this chapter identifies examples of successful CS programs as well as considering practical issues such as the reliability of the data, participant recruitment and motivation, and the use of emerging technologies.

Stable isotopes of carbon and nitrogen were used to determine the different carbon pathways and trophic assemblages amongst coastal benthic fauna of the Windmill Islands, East Antarctica. Macroalgae, pelagic POM, sediment POM and sea ice POM had well-separated δ 13 C signatures, which ranged from −36.75‰ for the red alga Phyllophora antarctica , to −10.35‰ for sea ice POM. Consumers were also well separated by δ 13 C, ranging from −21.42‰ for the holothurian Staurocucumis sp. up to −7.47‰ for the urchin Sterechinus neumayeri . Analysis of δ 13 C and δ 15 N revealed distinct groups for suspension feeders, grazer/herbivores and deposit feeders, whilst predators and predator/scavengers showed less grouping. Consumers spanned a δ 15 N range of 8.71‰, equivalent to four trophic levels, although δ 15 N ratios amongst consumers were continuous, rather than grouped into discrete trophic levels. The study has built a trophic model for the Windmill Islands and summarises three main carbon pathways utilised by the benthos: (1) pelagic POM; (2) macroalgae/epiphytic/benthic diatoms and (3) sediment POM/benthic diatoms. The movement of carbon within the coastal benthic community of the Windmill Islands is considered complex, and stable isotopes of carbon and nitrogen were valuable tools in determining specific feeding guilds and in tracing carbon flow, particularly amongst lower-order consumers.

We review the status of marine shellfish ecosystems formed primarily by bivalves in Australia, including: identifying ecosystem-forming species, assessing their historical and current extent, causes for decline and past and present management. Fourteen species of bivalves were identified as developing complex, three-dimensional reef or bed ecosystems in intertidal and subtidal areas across tropical, subtropical and temperate Australia. A dramatic decline in the extent and condition of Australia’s two most common shellfish ecosystems, developed by Saccostrea glomerata and Ostrea angasi oysters, occurred during the mid-1800s to early 1900s in concurrence with extensive harvesting for food and lime production, ecosystem modification, disease outbreaks and a decline in water quality. Out of 118 historical locations containing O. angasi-developed ecosystems, only one location still contains the ecosystem whilst only six locations are known to still contain S. glomerata-developed ecosystems out of 60 historical locations. Ecosystems developed by the introduced oyster Crasostrea gigas are likely to be increasing in extent, whilst data on the remaining 11 ecosystem-forming species are limited, preventing a detailed assessment of their current ecosystem-forming status. Our analysis identifies that current knowledge on extent, physical characteristics, biodiversity and ecosystem services of Australian shellfish ecosystems is extremely limited. Despite the limited information on shellfish ecosystems, a number of restoration projects have recently been initiated across Australia and we propose a number of existing government policies and conservation mechanisms, if enacted, would readily serve to support the future conservation and recovery of Australia’s shellfish ecosystems.

It is a fundamental tenet of Rapid Biological Assessments (RBA) that the samples collected reflect the community from which they are drawn. As with any biological sampling, RBA collections are subject to sampling error resulting in the omission of some taxa. The aim of this study is to compare the composition of RBA samples with an estimate of community structure based on extensive quantitative sampling. We used logistic regression to explore the relationships between the frequency of a taxon being collected in an RBA sample and its biological and ecological traits, namely its abundance, distribution, body size and habit. RBA samples and quantitative estimates of community structure were made in riffles in the Kangaroo and Nepean Rivers, New South Wales, Australia. Single RBA samples may collect up to 63% of the taxa that are collected by extensive quantitative sampling at a site. The frequency of a taxon being recorded in an RBA sample was significantly and positively related to all traits tested indicating a bias in the collection methods towards large, abundant and widely distributed taxa. Accordingly, taxa missed by RBA sampling were generally small, narrowly distributed or rare. These findings enhance our understanding of what RBA samples represent, and the bias and source of errors associated with RBA sampling. This study also quantifies the utility of RBA methods for biodiversity assessment.

[Extract] Some 29% of Australian estuaries are considered to be 'extensively modified' or 'modified' – particularly those in the east, south-east and south-west (NLWRA 2002). Additional nearshore marine habitats (notably once extensive oyster reefs and mussel beds) are functionally extinct throughout most of Australia, and most Australians are unaware this loss has even occurred (Beck et al. 2011; Alleway & Connell 2015). These declines follow the global norm and come as no surprise. What is surprising then, is that despite Australia’s global reputation as a leader in marine science, natural resource management and national landcare initiatives, restoration of marine environments has been largely 'off the radar' in terms of the national agenda.... So what needs to occur to galvanize public and private support for large-scale marine restoration efforts? Below are five key elements that we believe need increased attention in order to increase the scale of marine restoration to levels that are ecologically, socially and economically meaningful.

Knowledge of the trophic functioning of Southern Ocean ecosystems is critical to their understanding and management. Marine ecosystem models, often used to explore the potential impacts of human disturbance and climate change, and for fisheries stock assessments, generally rely on suitable data to underpin the parameterization of taxon attributes and diets. Diet-related data from published and unpublished data sets and studies were collated into a single consistent data set, circum-Antarctic in scope, with two principal tables. The first table relates to direct sampling methods of dietary assessment, including gut, scat, and bolus content analyses, stomach flushing, and observed feeding. It currently comprises ∼25 000 records from 300 studies and includes information on >1000 taxa. The second table is a compilation of stable isotope values (currently 1500 records from 20 studies, covering 200 taxa). Each record in these two tables includes details such as the location and date of sampling, predator size a...