Beach Litter Assessment: Critical Issues and the Path Forward

Abstract

Studies analyzing large-scale patterns or long-term trends in the amounts and composition of beach litter are often based on the analysis of several small-scale studies, which may provide an inaccurate picture if the methods and approaches used in those studies are not directly comparable. Moreover, most beach-litter review studies do not evaluate how the results are affected by a number of factors. Therefore, this paper analyzes empirical results from 62 beach-litter (BL) assessment studies published in the last decade (years 2010-2020) in peer-reviewed international journals. Both the results on beach litter (origin, composition, and density) and the utility of those findings to coastal managers are analyzed and discussed. The paper identifies strengths and weaknesses of different research designs, overall compatibility among the results of studies, and identification and means of eliminating those aspects that cause incompatibilities, inconsistencies, and high variability of data that cause low reliability of the results, among other issues. The results indicate that a global picture based on a number of small-scale studies cannot be drawn due to incompatibilities in sampling protocols and presentation of results, data analysis and interpretation, spatial and temporal differences, and the lack of understanding of factors influencing BL. This paper offers a critical view of many aspects of (BL) research in order to bring them to researchers' attention, at the same time recognizing the importance of previously published studies in making significant advancements in this field. Finally, it is also a call to move from limited data collecting and presentation in peer-reviewed journals to experimental designs, large data analyses, and testing of methods and solutions to the BL issue to advance understanding of beach-litter issues.