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Anthropogenic debris is a global threat that impacts threatened species through various lethal and sub‐lethal consequences, as well as overall ecosystem health. This study used a database of over 24,000 beach surveys of marine debris collated by the Australian Marine Debris Initiative from 2012 to 2021, with two key objectives: (1) identify variables that most influence the occurrence of debris hotspots on a continental scale and (2) use these findings to identify likely hotspots of interaction between threatened species and marine debris. The number of particles found in each beach survey was modelled alongside fifteen biological, social, and physical spatial variables including land use, physical oceanography, population, rainfall, distance to waste facilities, ports, and mangroves to identify the significant drivers of debris deposition. The model of best fit for predicting debris particle abundance was calculated using a generalized additive model. Overall, debris was more abundant at sites near catchments with high annual rainfall (mm), intensive land use (km2), and that were nearer to ports (km) and mangroves (km). These results support previous studies which state that mangroves are a significant sink for marine debris, and that large ports and urbanized catchments are significant sources for marine debris. We illustrate the applicability of these models by quantifying significant overlap between debris hotspots and the distributions for four internationally listed threatened species that exhibit debris interactions; green turtle (26,868 km2), dugong (16,164 km2), Australian sea lion (2903 km2) and Flesh‐footed Shearwater (2413 km2). This equates to less than 1% (Flesh‐footed Shearwater, Australian sea lion), over 2% (green sea turtle) and over 5% (dugong) of their habitat being identified as areas of high risk for marine debris interactions. The results of this study hold practical value, informing decision‐making processes, managing debris pollution at continental scales, as well as identifying gaps in species monitoring. [ABSTRACT FROM AUTHOR]

Plastic debris within marine environments is an issue of global concern, leading to commitments at international, regional, and national scales to remove plastics from the environment and prevent further entry. The United Nations (UN) created a global framework of 17 Sustainable Development Goals (SDGs), with several goals to advance the environmental dimension of sustainable development, with global and country progress tracked by targets and their indicators. Countries voluntarily report their progress on the basis of guidance provided by the UN on what data is needed. SDG 14, Life Below Water, contains one target to significantly reduce marine pollution, with specific mention of plastic debris. To date, however, national information on plastic debris has been sparse, although citizen science projects have been collecting data at a spatial and temporal coverage relevant to SDG reporting. This paper provides an overview to clarify the data requirements for reporting on the SDG indicator of plastic debris density and the complex process in which data for SDGs is requested from and provided by countries. We then explore the potential for citizen science to assist countries in filling evidence gaps, through providing data on plastic pollution. We focus on the sub-indicator for beach debris, which accounts for most citizen science projects collecting data on plastic pollution. Then, we unpack the opportunities and challenges of augmenting SDG reporting with information gathered from citizen science communities. Lastly, we recommend ways for citizen science communities and governments to synergize efforts monitoring plastics to inform pathways for preventing and reducing such pollution ending up in our marine environments. [ABSTRACT FROM AUTHOR]

Global momentum to address plastic pollution has led to the development of national processes to monitor plastics into and within the environment. The Sustainable Development Goals (SDGs) provide guidance for reporting on plastic pollution, although compiling national estimates remains a challenge. Data availability remains a key barrier, which could be addressed through engagement with the citizen science community, which collects and maintains data at a resolution suitable for SDG reporting. Here, we demonstrate a process that uses citizen science monitoring of plastic debris on beaches to report on SDGs at the national scale. The study uses the Australian Marine Debris Initiative (AMDI) Database, which is composed of data submissions from over 1400 organisations across Australia. The AMDI was used to provide initial estimates of plastic debris density both nationally and across Natural Resource Management areas (NRMs). Before analysis, the database was filtered for data quality and alignment with guidance for SDG reporting (i.e., SDG Indicator 14.1.1b), resulting in the analysis of 3144 events across 538 sites between 2014 and 2019 (inclusive). The average density of plastic debris on beaches across Australia was between 0.155 and 0.279 counts m−2, with management relevant trends identified across NRMs. This study demonstrates the potential for the citizen science community to support SDG reporting and management processes, which could inform and enable actions to address plastic pollution. [Display omitted] • Citizen science enabled preliminary estimates of SDG Indicator 14.1.1b across Australian beaches. • Plastic debris density was analysed from 538 sites and 3144 events from 18 sub-national regions. • Plastic debris density in Australia was estimated between 0.155 and 0.279 counts m−2 between 2014 and 2019. • SDG Indicators could establish processes for citizen science to inform policy and management. • Investment into citizen science supports evidence generation for SDG reporting. [ABSTRACT FROM AUTHOR]

We describe the design and structure of a web-based visualization tool for an Australian marine debris database and its application in environmental research, management and science communication. We give examples of its use in generating hypotheses regarding processes driving the distribution of marine debris, identifying source reduction opportunities and communicating science to the public and stakeholders. We suggest this as a model for utilizing other latent environmental data sets, enabling users to implement the five 'source-to-sea' steps to characterize, engage, diagnose, design, act and adapt when addressing leading environmental concerns. [ABSTRACT FROM AUTHOR]

Estuaries are under increasing pressure from urbanization, including through the release of domestic wastes such as anthropogenic debris. Growing concern over environmental contamination has led to management interventions, aimed at reducing the further release of debris. Effective strategies, however, require an understanding of the factors influencing the abundance and distribution of debris. Estuaries pose a challenge to assess debris trends due to the myriad of factors that influence debris patterns. Here we present a Bayesian approach to assess spatial patterns in debris across four estuaries of New South Wales, Australia. We provide an overview of debris composition and employ Integrated Nested Laplace Approximation (INLA) alongside Stochastic Partial Differential Equation (SPDE) to produce three models testing predictors of debris abundance: (i) non spatial, (ii) a model accounting for spatial autocorrelation and (iii) accounting for spatial autocorrelation and introducing the estuarine foreshore as a barrier. Data was sourced from cleanups reported within the Australian Marine Debris Initiative (AMDI), a national citizen science program coordinated by the Tangaroa Blue Foundation. The data, from 169 sampling events between 2012 and 2017 was used. All models tested predictors against the abundance of hard plastic, expanded plastic, plastic bags, and plastic drink bottles. Plastic was the dominant component, ranging from 69% to 82% of total debris within the study estuaries. Important predictors differed across debris types and included 'distance to estuary mouth', access to foreshore, population, and site substrate. Specific factors differed in importance when accounting for spatial autocorrelation, demonstrating the need for spatial approaches when assessing debris trends within estuaries. The present Bayesian approach could be used to better understand drivers of estuarine debris and inform interventions for effective management. [Display omitted] • Plastic items accounted for 74%–84% of all items found across four estuaries. • Bayesian modelling assessed drivers using non-spatial, spatial and barrier models. • Distance to estuary mouth, population and sediment characteristics were important factors. • Modelling spatial autocorrelation and using barriers changes inference. [ABSTRACT FROM AUTHOR]

Globally, single-use plastics (i.e., items only used once before being discarded plastic, such as straws, plastic bags, cigarette butts) are a substantial contributor of debris in the environment. In response, policy interventions to minimise single-use plastics and packaging have increased in the past decade (e.g., national and state level bans on plastic bags). Reduction strategies that tackle debris items at the source (i.e., Source Reduction Plans (SRPs)) have been suggested as a key strategy to achieve a reduction in debris in the environment. SRPs differ in their implementation approach, since different items require different methods depending on their characteristics, pathway, and source. In Australia, several SRPs have been applied by communities and the Tangaroa Blue Foundation (TBF). Globally, there is a lack of information available concerning the challenges associated with the implementation of SRPs, such as policy considerations and costs. Therefore, there is a need to measuring the effectiveness of specific SRPs as mitigation tools, to identify their strengths and weaknesses, and determine the best reduction approaches for specific items. We measured the effectiveness of two quantifiable SRP projects at different scales: cigarette butts (consumer level) and strapping bands used in fisheries (industrial level). There was a marginally significant decline in strapping bands in the environment over time (2004–2020), although we were unable to associate this directly to the SRP intervention (ban on ships). At a consumer level, there was a decline in the rate of cigarette butts flicked on the ground during sporting events post-SRP, with an overall reduction of 45.4% in number of cigarettes per spectator. Our results suggest the outcomes differ depending on the type of SRP, due to the different characteristics of the tackled item (i.e., source, pathway) and the respective SRP implementation mechanism. We highlight the importance of SRPs and make recommendations on future steps towards reducing single-use plastics in the environment. [Display omitted] [ABSTRACT FROM AUTHOR]

Plastic pollution poses environmental and socio-economic risks, requiring policy and management interventions. The evidence-base for informing management and evaluation of their effectiveness is limited. Partnerships with citizen scientists provide opportunities to increase the spatio-temporal scale of monitoring programs, where training and standardised protocols provides opportunities for the use of data in addressing multiple hypotheses. Here, we provide a baseline of debris trends and infer debris drivers of abundance across 18° of latitude, using 168 surveys from 17 beaches across Queensland, Australia through the ReefClean project. Plastics were the dominant material (87% of total debris, with hard, soft and foam plastics aggregated), although linking recovered debris to sources was limited, as 67% of items were fragmented. We tested potential drivers of specific debris types (i.e., plastics, commercial fishing items, items dumped at-sea, and single-use items) and identified significant relationships between debris accumulation with distance from the nearest population centre and site characteristics (modal beach state, beach orientation and across-beach section). Management efforts should consider beach type and orientation within site selection, as an opportunity to maximise the amount recovered, alongside other criteria such as the risks posed by debris on environmental, economic, and social values. This study demonstrates the utility of citizen science to provide baselines and infer drivers of debris, through data gathered at scales that are infeasible to most formal monitoring programs. The identified drivers of debris may also differ from regional and global studies, where monitoring at relevant scales is needed for effective management. [Display omitted] • Standardised surveys across 18° latitude were conducted to assess debris drivers. • Site orientation and beach type were key physical drivers of debris trends. • Debris types were linked to different factors driving accumulation on beaches. • Partnerships with citizen science provide the data to infer debris drivers. • The study provides a monitoring approach for State-wide debris management. [ABSTRACT FROM AUTHOR]

To mitigate marine debris and promote sustainable marine industries, legislation and regulations surrounding the management of marine debris have been adopted worldwide. One of the most well-known and important agreements is the International Convention for the Prevention of Pollution from Ships (MARPOL), which focuses on reducing all types of ship-sourced marine pollution. MARPOL Annex V, which deals with the disposal of solid waste, came into force on 31 December 1988. However, was only amended to include a complete ban on waste disposal as of 1 January 2013. Assessing the effectiveness of key regulations is fundamental for supporting evidence-based decisions regarding the management of our oceans. Here, we evaluated whether MARPOL Annex V translated into a decrease in the incidence of shipping- and commercial fishing-sourced debris on remote beaches in Australia using 14 years of standardised, community-driven data. From 2006 to 2020 there was a significant change over time in the density of fishing and shipping debris on Australian beaches; debris density increased up to 2013 followed by a decrease until mid-2017. Although the new regulation started in January 2013, the decrease in density was not recorded until one year later. The decline was only observed for 4 years, reinforcing the existence of lags between the implementation of international agreements and the corresponding potential reduction in debris in the environment. This provides compelling evidence that international agreements and policies by themselves are not enough to solve the debris problem, with improved implementation and enforcement also required. We discuss future perspectives and solutions to reduce ocean-sourced litter inputs into the ocean and highlight the urgent need for action. [Display omitted] • We assessed the effectiveness of MARPOL Annex V in reducing ocean-sourced debris. • Thirteen years of standardised community-driven data in Australia were analysed. • We observed a significant change in the density of ocean-sourced debris over time. • A lag persists between MARPOL Annex V implementation and the observed results. • We highlight the urgent need for action to reduce ocean-sourced litter. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) pollution in the marine environment is a pressing issue in Queensland, Australia due to a recent flood that scattered hundreds of EPS-containing pontoons along the coastline, causing severe ecological damage. To assist in the clean-up effort and provide crucial data for developing management guidelines, this study investigates the environmental performance of different end-of-life (EoL) disposal/recycling methods, including (i) landfill; (ii) on-site mechanical re-processing using a thermal densifier (MR); and (iii) on-site dissolution/precipitation using d -limonene (DP). Applying the life cycle assessment framework, the results showed that DP was the most environmentally favourable option. Its impacts in climate change (GWP), acidification (TAP), and fossil fuel depletion (FFD) were 612 kg CO 2 eq, 4.3 kg SO 2 eq, and 184.7 kg oil eq, respectively. For comparison, the impacts of landfilling EPS in these categories were found to be 700 kg CO 2 eq, 3.5 kg SO 2 eq, and 282 kg oil eq, respectively. Landfill also contributed considerably to eutrophication potential (MEP), at 3.77 kg N eq. Impacts from MR were most significant due to the need to transport the densifier unit to the site. The analysis also revealed that the transportation of personnel and heavy machinery to the site, was the biggest contributor to impacts in the EoL stage. Its impacts in GWP, TAP, MEP, and FFD were 1369.8 kg CO 2 eq, 6.5 kg SO 2 eq, 0.2189 kg N eq, and 497.7 kg oil eq, respectively. Monte Carlo analysis showed that the conclusions made from these results were stable and reliable. Limitations of this model and recommendations for future investigations were also discussed in this work. [Display omitted] • Transportation imposed the highest impacts during disposal of missing pontoons. • Mechanical re-processing had highest impacts. • d -limonene dissolution showed the best environmental performance. • Further research is needed to optimise d -limonene dissolution process. • Recovery of PS is desirable, but not feasible. [ABSTRACT FROM AUTHOR]

Remote, data-limited marine environments are poorly understood, making conservation and resource management major challenges in the rapidly changing environment. High field data collection costs results in sparse data, which limits the traditional scientific approach to understand the functioning of these remote ecosystems. The Gulf of Carpentaria is a vast, remote and data-limited region in northern Australia that is vulnerable to rapid changes due to climate change and externally derived marine debris, but extremely difficult and costly to access. This study aimed to test a method of improving certainty in ecological and physical processes in the Gulf of Carpentaria by maximising the use of alternative biophysical data from local Indigenous-owned and managed land and sea country, to elucidate the ecosystem functioning. We investigated the role of currents and wind in previously published Green turtle (Chelonia mydas) post-nesting satellite tracking migration data, and found they had no influence on the turtles' migration path. We also found that turtles did not use compass bearing alone to make their migration, rather they seemingly used coastal cues to 'leap-frog' along the coastline until they reached their foraging grounds. Next, we identified the spatio-temporal distribution of floating marine plastics using Indigenous-lead citizen science coastal marine debris surveys, and found that previous studies have underestimated marine debris presence in the region. Finally, biophysical modelling suggests that large migrations (>200 km in 28–35 days) of tagged male Giant mud crabs (Scylla serrata) against prevailing winds, currents and tides were possible by using selective tidal stream transport and directional swimming. These case-studies demonstrate the effectiveness of explorative biophysical modelling supported by alternative field data, and improve certainty in ecological processes with significance in culture, conservation and commercial values in the region. [Display omitted] • Remote and data-limited locations need creative scientific enquiry and participation with Indigenous and commercial communities. • Post-nesting migrating green turtles swim strongly against the currents and use coastal cues to navigate. • Marine debris in the Gulf of Carpentaria has been underestimated in past studies. • Giant mud crabs (Scylla serrata) used selective tidal stream transport to travel 200 km in 28–35 days. • Biophysical modelling could be adopted globally in remote and data-limited locations to advance marine ecological knowledge. [ABSTRACT FROM AUTHOR]