Three-dimensional evaluation of beaches of oceanic islands as reservoirs of plastic particles in the open ocean

The quantification of plastic debris on beaches has been extensively used as an indicator of plastic pollution in the marine environment. However, most efforts have focused on surface layers, with few investigations looking deeper into the substrate, thus underestimating total standing stocks. Such information is crucial to improve our understanding of where plastic accumulates in the oceans. In this study, we investigated the three-dimensional distribution of plastic (>1 mm) in three sandy beaches located in oceanic islands of the North Atlantic (Azores and the Canary Islands) that are known to accumulate significant quantities of small plastic debris at the surface layer. On each beach, we collected a total of 16 sediment cores down to 1 m depth, from the high tide line up to the backshore following a stratified random sampling design spread across four different levels across the beach. Samples were taken every 10 cm down to 1 m into the sand. Our results revealed the presence of plastic items in the deepest layers with subsurface layers accounting for 84 % of the total plastic abundance and with a similar pattern in terms of size, shape, colour and composition. Furthermore, we found increasing plastic concentrations towards the upper levels of the beach, indicating longer term accumulation in the backshore. Collectively, this study suggests that the plastic items reaching sandy beaches of the Macaronesia are being incorporated into its deepest layers, acting as reservoirs of plastic in the open ocean.

Assessing the effectiveness of MARPOL Annex V at reducing marine debris on Australian beaches

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.

Investigation on beach debris on the historical nesting grounds of green turtles (Chelonia mydas) in Hainan Island, South China

Hainan Island used to be the most important nesting ground of green turtles in China before they disappeared about 37 years ago. Habitat degradation is one of the main reasons for the disappearance of sea turtles. Therefore, it is necessary to take action to evaluate and recover the historical nesting grounds if we hope for sea turtles to return in the future. In this study, we surveyed the beach debris on 13 historical nesting grounds of green sea turtles on Hainan Island. The beach debris on these nesting grounds mainly consisted of plastic, cigarette butts, foam, glass, and nylon, with plastic (including plastic blocks, cigarette butts, and foam) being the dominant type, accounting for 78.92% in number, followed by glass. The average density of beach debris was 0.314 pieces·m^-2. Compared to other nesting grounds, the average quantity and density of beach debris in Hainan was lower, but the proportion of plastic debris was extremely high. After categorizing debris type, we found that most was from human coastal activities (35.54%), with debris at tourist beaches having the biggest proportion of debris from smoking supplies. The distribution characteristics of beach debris were related to the function of the beach, density of tourist, and the intensity of beach debris cleaning. It is recommended to further strengthen the emission reduction and clean-up of beach debris in Hainan Island, so as to restore the nesting habitat of sea turtles as soon as possible.

Anthropogenic litter on the macrotidal sandy beaches of the Amazon region

Coastal zones, which are strategic points of considerable importance to the tourism industry, are among the environments most affected by anthropogenic debris. Thus, it is crucial to monitor and implement management programs to provide immediate solutions. Here, we aimed to evaluate anthropogenic litter along 21 macrotidal sandy beaches in the Amazon region. Indices and multivariate statistical analyses were used to identify spatial patterns of pollution, as well as sources and lifetime of the items. A total of 20,286 items were collected, with an average density of 0.19 items/m² and a predominance of plastics. Litter was associated with tourist and recreational activities. The lifetime of most items was <1 year. All beaches had intermediate levels of pollution. The analyses identified varying patterns of anthropogenic litter related to the cleaning frequency and waste item typologies. In conclusion, pollution of macrotidal beaches in the Amazon region is an emerging problem that requires measures to prevent and mitigate the impacts on this ecosystem and to reconsider the form of production and consumption of plastic waste.

The spatiotemporal dynamics, distribution, and characteristics of beached plastics along the remote south coast of Western Australia

Understanding the accumulation mechanism for beached plastics is important for marine debris research. Similar to the global accumulation pattern for beached plastics, we find that along the remote south coast of Western Australia (SCWA) white, hard, microplastics dominate the microplastic pollution accumulating on beaches. We estimate that along the SCWA, plastics are present at a density of 2.01 items·m^-2, but also find that the density of plastic pollution is higher at the eastern end of bays. Significantly fewer plastics were found after easterly winds (austral summer-prevailing winds), and regional physical ocean process, including the Leeuwin Current, and the Ekman transport effect may be relevant to the rate of plastic accumulation on SCWA beaches.

Beach debris quantity and composition around the world: A bibliometric and systematic review

Anthropogenic pollution of marine ecosystems caused by beach debris has become a serious environmental concern in the last few decades. Regarding the raising production of beach debris, the present work aimed to summarize the quantity and quality of beach debris reported from different beach areas of the world. Also, a bibliometric analysis was used to analyze research trends and upgrade knowledge in this research area. Using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA), the eligible papers reviewed regarding beach debris abundance along with their composition from 2010, which were extracted from the Scopus database. The results of the study showed that plastic items represented the dominant material (61.25%), followed by food (5.88%), wood (5.78%), metals (5.2%), and glass (5%). Further, the beaches studied were classified into three degrees, including highly polluted (31.5 items/m2), moderate polluted (3.47 items/m2), and low polluted (0.37 items/m2), based on the average abundance of debris.

Disentangling beach litter pollution patterns to provide better guidelines for decision-making in coastal management

Beach litter represents a worldwide problem impacting both terrestrial and aquatic environments. In the present study, we assessed beach litter pollution in a prominent touristic site in Brazil, the Jericoacoara National Park. In particular, we applied a delta-generalized additive modeling (GAM) approach in order to investigate pollution hotspots and to provide better guidelines for coastal environmental managers. A total of 7549 litter items were collected, resulting hard and flexible plastics the most abundant type. Our GAM analysis revealed that the distribution of each type of litter was affected by distinct drivers in the protected area, with the extension of the beach, tourist attractions, wind angle, and the distance to water bodies and villages as the most significant explanatory variables. Our model is suitable in predicting litter pollution hotspots on beaches, which is a valuable tool for future guidelines and effective management strategies to prevent beach pollution worldwide.

An approach to the integration of beach litter data from official monitoring programmes and citizen science

Marine litter on Spanish beaches is assessed through two monitoring programmes: the Official Monitoring Programme of Marine Litter on Beaches (BM-1) developed by the Spanish Ministry for the Ecological Transition and the Demographic Challenge and the Citizen Science Monitoring Programme (BM-7) that provides beach litter data from voluntary clean-up initiatives. So far, the data provided by both programmes have been analysed separately although their integration could improve the assessment of the situation of Spanish beaches regarding marine litter. To this end, this paper studies the possible integration of both datasets through the calculation of a baseline value for marine litter on Spanish beaches. Statistical analysis of data shows that both datasets produce similar values and also integrate in a consistent way to achieve a value of 128 items/100 m as a baseline value for beach litter in Spain.

A comparative study of deep learning-based network model and conventional method to assess beach debris standing-stock

The conventional survey of marine debris standing-stock has various drawbacks such as high cost and inaccuracy because the total amount of debris in the whole beach is inferred using the results of the manual investigation in selected narrow areas. To overcome the disadvantages, an automatic detection method using a deep learning-based network model was developed to detect and quantify the beach debris. The network model developed in this study classified items with a precision of 0.87 (87%) mAP and showed <5% error compared to actual survey. This study is the first fieldwork in Korea that shows the difference between automatic and conventional methods to predict the beach debris standing-stock. The results provide essential information for the development of effective beach debris management systems and policies.

Density and composition of surface and buried plastic debris in beaches of Senegal

Debris poses a series of problems to marine life and human well-being. However, estimates of density and characteristics of debris found on beach surfaces and buried in the sand are patchy on a global scale and absent for West Africa. Here we investigate the density of surface and buried debris accumulated in two beaches with contrasting levels of urbanisation in Senegal, West Africa. We also describe type, colour, weight, size, and possible source of the 1766 items collected. The average density of debris buried at a depth of 10 cm (48.75 items/m²) was 25 times higher than that observed at the surface (1.92 items/m²). Plastics accounted for 97.62% of the items. Plastic bags and clothing plastic were the most common types, whereas white and transparent were the most common colours. Most items originated from mixed sources, i.e. beach users and land-based sources (51.30%). Debris density in the urbanised site was 20 times higher than that in the non-urbanised site. Debris density can, therefore, be largely underestimated when sampling only on the beach surface. Our study provides the first findings for future research on beach debris in Senegal.

Anthropogenic litter on Brazilian beaches: Baseline, trends and recommendations for future approaches

Beaches are fundamental habitats that regulate the functioning of several coastal processes and key areas contributing to national and local budgets. In this study we provide the first large-scale systematic survey of anthropogenic litter on Brazilian beaches, covering a total of 35 degrees of latitude, recording the litter type, its use and size. Plastic comprised the most abundant litter type, followed by cigarette butts and paper. Small pieces (<5 cm) were dominant among litter size-classes and food-related use was associated to most litter recorded types. Generalized additive models showed that proximity to estuarine run-offs was the main driver to beach litter accumulation, reinforcing river drainages as the primary route of litter coastal pollution. Also, the Clean-Coast Index evidenced there was not a pattern of beach litter pollution among regions, which denotes that actions regarding marine pollution must be taken by all state governances of the country.

Beach litter distribution along the western Mediterranean coast of Spain

The amount and composition of beach litter was assessed, during spring 2018, at 56 sites along the coast of Alicante Province, on the western Mediterranean Sea. Selected sites covered "natural" (19), "village" (17) and "urban" (20) bathing areas and a total of 10,101 litter items was counted in an area of 201,686 m². Plastic represented the dominant material with 8345 items, i.e. 82.6% of all debris; paper and cardboard numbered 566 items (i.e. 5.6%); pottery and ceramics 348 (3.4%); metal 325 (3.2%); cloth 231 (2.3%); glass 147 (1.5%); rubber 64 (0.6%); wood 46 (0.5%) and other materials summed 29 items, i.e. 0.3% of all debris. Cigarette butts, 45.6% of total items, were observed at different coastal sites: i.e. 1028 units at natural, 1148 at village and 2431 at urban sites. Despite the efforts of local administrations, which enforced cleaning operations at most sites, litter items were essentially related to beachgoers followed by wastewater discharges and fishing activities.

Marine debris in Trindade Island, a remote island of the South Atlantic

Marine debris is widespread in oceans worldwide, including the most remote locations. Here, for the first time, we report macro-debris accumulation on beaches of Trindade Island, a remote island 1160 km from mainland Brazil. High debris density was recorded on windward, east-coast beaches, which are exposed to wind-driven currents. Small-sized plastic fragments were the most abundant debris. Polyethylene (67%), polypropylene (30%) and polyamide (3%) were the most prevalent polymeric materials identified by ATR-FTIR. Identified debris show that interaction with Trindade fauna, mainly with seabirds and endangered terrestrial crabs, exists and already has some impact. This study provides baseline information on Trindade macro-debris demonstrating that the island, located on the edge of the South Atlantic Gyre, acts as a sink for gyre debris, exposing the island fauna to the threats related to plastic contamination.