Macroplastics in Lakes: An Underrepresented Ecological Problem?

Lakes are the greatest reserve of available superficial inland fresh water and concurrently one of the most threatened ecosystems. Among the many pollutants, plastics contaminate lakes worldwide; notwithstanding that, little is known on the impacts of macroplastics. The aim of this work is to provide the first global overview of scientific articles researching macroplastic pollution in lakes. Articles were selected from Web of Science and Scopus databases. We performed a bibliometric analysis of the results on the publication trend, geographical distribution of study areas, investigated matrix (i.e., water, sediment, biota), as well as abundance and type (i.e., shape, litter category, polymer) of lacustrine macroplastics. We also compared the articles' methodologies. Fourteen articles were collected (the publication trend is increasing in recent years), showing a diffuse contamination by macroplastics. Research efforts are mostly focused on shoreline assessments. There is a lack of information and methodological standardisation (i.e., macroplastic size definition, sampling protocol, shape, litter categories), which limits the comparison of article outputs. We propose the definition of lacustrine macroplastics as plastics >5 mm and the adoption of the UNEP/IOC protocol to sample lake shoreline. We suggest focusing future investigations on (1) testing the methodological standardisation, (2) understanding the factors influencing macroplastic dispersal, and (3) assessing the impacts on biota.