Increasing our understanding of coastal microplastics and mesoplastics: a comparison of sampling methodologies using volunteer researchers

Abstract Coastal microplastic and mesoplastic pollution has become a significant issue for the environment, ecosystems and potentially human health, and the problem is so pervasive that traditional science is struggling to measure its true impact. Citizen science research projects in this field present an opportunity to augment existing research and potentially provide benefits to the volunteers. However, different sampling methodologies and the absence of a standardised protocol, makes it difficult to make meaningful comparisons between data collected globally. In this study we compared three existing sampling protocols. These methods included two citizen science sampling protocols, the Big Microplastic Survey (BMS), and the Australian Microplastic Assessment Project (AUSMAP), and the scientific recommendations of the European Union Marine Strategy Framework Directive (MSFD). We used volunteers to undertake the sampling in both uncoordinated and coordinated surveys across three locations in the south of the UK. In two locations we found that the BMS method consistently provided higher counts of plastic pollution, and fewer zero counts than the AUSMAP and MSFD methods. In another location, BMS and AUSMAP produced comparable results. We conclude that standardisation remains a challenge, and that further research should focus on establishing a means to allow data collected by different methods to be compared.