Global Review of Beach Debris Monitoring and Future Recommendations Catarina Serra-Goncalves,̧ † Jennifer L
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Critical Review Cite This: Environ. Sci. Technol. 2019, 53, 12158−12167 pubs.acs.org/est Global Review of Beach Debris Monitoring and Future Recommendations Catarina Serra-Goncalves,̧ † Jennifer L. Lavers,*,‡ and Alexander L. Bond‡,§ † University of Tasmania, Institute for Marine and Antarctic Studies, School Road, Newnham, Tasmania 7250, Australia ‡ University of Tasmania, Institute for Marine and Antarctic Studies, 20 Castray Esplanade, Battery Point, Tasmania 7004, Australia § Bird Group, Department of Life Sciences, The Natural History Museum, Tring, Hertfordshire HP23 6AP, United Kingdom *S Supporting Information ABSTRACT: Marine debris is distributed worldwide and constitutes an increasing threat to our environment. The exponential increase in the level of plastic debris raises numerous concerns and has led to an intensification in plastic monitoring and research. However, global spatial and temporal patterns and knowledge gaps in debris distribution, both on land and at sea, are relatively poorly understood, mainly due to a lack of comprehensive data sets. Here, we critically review the quality of the available information about beach plastic debris worldwide to highlight where the most urgent actions are required and to promote the stand- ardization of reporting metrics and sampling methods among researchers. From a total of 174 studies evaluated, 27.0% reported marine debris densities in metrics that were not comparable. Some studies failed to report basic parameters, such as the date of the sampling (9.8%) or the size of the collected debris (19.5%). Our findings show that current research regarding beach debris requires significant improvement and standardization and would benefit from the adoption of a common reporting framework to promote consensus within the scientific community. 1. INTRODUCTION Plastic debris can result from numerous human activities but is broadly categorized into either land- or marine-based Plastic products, especially single-use items, have become sources.19 Approximately 80% of all debris originates on widespread in our society, and as a result, production and 1,2 land, being of particular concern in coastal ecosystems where it disposal have increased drastically in recent decades. A lack − 14,20 ff represents 60 80% of litter on beaches. These same areas of e ective waste management and mitigation strategies, are important to local communities and tourism; therefore, particularly in low- and lower-middle-income countries, has debris has the potential to damage the aesthetic value of resulted in the accumulation of large amounts of plastic debris Downloaded via UNIV OF TASMANIA on November 6, 2019 at 10:16:13 (UTC). 3−5 shorelines and, consequently, their economic value. Further- in the environment. Often termed marine debris, it is more, the degradation of these habitats constitutes a major fi de ned as any persistent, manufactured or processed solid threat for the myriad marine and coastal species that rely on See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. material made or used by humans and either deliberately or them.21,22 The accessibility of coastal ecosystems, combined accidentally discarded, disposed of, or abandoned in the with the visible manifestation of debris on beaches, has led to 8 marine and coastal environment. Monitoring of aquatic the majority of data on debris being derived from beach environments suggests the overall level of plastic (typically surveys.23 accounting for 61−87% of debris) is increasing,4,6,7,9 with In 2015, all United Nations Member States adopted the 17 plastic production and consumption rates showing no signs of Sustainable Development Goals (SDGs) as part of the “2030 slowing.10 Agenda for Sustainable Development”.24 Goal 14 aims to At present, plastic debris represents one of the most rapidly conserve and promote the sustainable use of the oceans, expanding and topical environmental hazards, due to the including the prevention and significant reduction in marine durability of plastic products and their diverse negative impacts pollution by 2025. Additionally, in 2016 almost 200 countries − on wildlife, habitats, and economies.11 13 Most, if not all, united as part of the Convention on Biological Diversity to marine environments (e.g., coastal zones, open ocean, and ratify the “Strategic Plan for Biodiversity 2011−2020”, which deep-sea sediments) are now contaminated by debris,14,15 with significant quantities reported even in the most remote corners Received: March 6, 2019 16,17 of the Earth. Debris distribution is influenced by ocean Revised: September 24, 2019 currents, wind, and waves, all of which can fragment items and Accepted: October 2, 2019 transport them over vast distances.18 Published: October 2, 2019 © 2019 American Chemical Society 12158 DOI: 10.1021/acs.est.9b01424 Environ. Sci. Technol. 2019, 53, 12158−12167 Environmental Science & Technology Critical Review includes Aichi Biodiversity Target 8 that aims to reduce all types of marine pollution by 2020.25 It is crucial to measure change and evaluate progress toward established international targets.26 There has been significant investment in plastic monitoring and research, especially since 2013; however, our understanding of this environmental issue remains largely based on individual surveys reporting the − abundance and type of beach debris at single locations.27 30 In the dynamic marine environment, these one-off surveys provide no information about changes over time, something that can be overcome only with robust sampling at the same site over many years. A handful of studies have reviewed the literature to identify factors that may influence the global distribution of beach − debris14,23,31 34 and have made recommendations for stand- ardized reporting metrics.32,35 However, assessing progress against global environmental policy targets remains difficult as the data generated through dozens of single-year, single- location beach debris studies undertaken in recent decades have not been reviewed. Therefore, there is an urgent need for a review and analysis of existing beach debris data so that researchers can better assess the global scale of this issue. Here, we provide an overview of the available information regarding beach debris abundance worldwide (a) to identify Figure 1. Flowchart showing the decision process for inclusion and global geographic distribution trends and gaps in beach debris exclusion of candidate beach debris literature identified using an ISI abundance and (b) to evaluate the performance of existing Web of Knowledge search. studies against established data standards. Through synthesiz- ing research outputs and translating data into a common From these 174 papers, the following information language (i.e., reporting metrics), we highlight where the most concerning beach debris was extracted, when available, for urgent actions are required to better understand the impacts of plastic and nonplastic items: (1) total debris abundance, (2) ff marine debris, enabling more e ective mitigation policies to be total debris density, (3) sampling location and year, (4) size developed. class of the sampled debris [macro-plastics (≥5 mm) and micro-plastics (0.2−5 mm)], (5) sampling method [surface 2. METHODS (0−2 cm) or buried debris (>2 cm)] with the corresponding 2.1. Literature Review. We conducted a systematic review depth when applicable, (6) reporting units, and (7) the most following established methods.36 An extensive search of the ISI common debris item by mass and number. Some studies Web of Knowledge database was conducted in April 2018 to contained more than one sampling location, and where search for publications using the following keywords: “beach possible, the beach debris density/mass data were reported debris OR beach OR beach litter” combined with “marine for each location independently; otherwise, a mean was debris OR plastic debris OR marine pollution OR plastic reported for all locations combined. In rare instances in pollution OR marine litter OR plastic litter OR plastic marine which data were reported from vegetated areas (e.g., dunes), it pollution OR marine plastic pollution OR marine plastic litter”. has been excluded from this review. Published values were Our search aimed to include all peer-reviewed papers converted to the same units (items per linear meter or items published before December 31, 2017. However, the results per square meter), when possible. Macro- and micro-debris missed some entries (see Discussion) and did not include densities were split and analyzed independently, because records from the gray literature or popular media. The micro-debris densities tend to be much higher and, therefore, contemporary literature typically adopts five main categories not comparable on the same scale with macro-debris densities. for debris size; however, there is some disagreement regarding From each study, we also recorded (1) the orientation of the the categories used (e.g., micro- and nanoparticles). Therefore, sampling location [leeward (LW) or windward (WW)], (2) we use only the two most common debris size categories: whether the sampling was conducted on an island or mainland − macro-debris (>5 mm) and micro-debris (0.2−5 mm).14,37 40 locality, (3) whether it was a community science study, (4) the We excluded all <0.2 mm debris. duration of the study (number of years: single-year vs On the basis of these search terms, we obtained 1060 multiyear studies) and if the respective multiyear studies