Floating Macrolitter Monitoring: From initial harmonization to a Global Reporting Tool

Quantifying floating macrolitter in rivers and seas contributes to designing effective mitigation strategies and evaluating environmental policies. This field has undergone a significant transformation over the last years, transitioning from fragmented local studies to large scale harmonized monitoring. This evolution is rooted in the first systematic effort to quantify riverine litter inputs, which established visual observation and the use of a mobile App as a robust and accessible method (González-Fernández & Hanke, 2017).

Building upon these foundations, the monitoring landscape has been further refined through scientific publications and the development of European and international guidelines. Such guidelines provide the scientific and methodological basis to ensure that data collected across different regions and basins are comparable and representative. Here we review data available in the literature and the use of the existing guidelines at global level.

In 2025, the European Commission has launched the new JRC Floating Litter Monitoring App. This digital tool integrates the official Joint List of Litter Categories and allows for real-time, geo-referenced data acquisition in both riverine and marine environments. Beyond its technical capabilities, the app is designed to be an effective tool for facilitating standardized reporting and data management. By bridging the gap between field observations and global databases, it enables a consistent evaluation of pollution levels at a global scale. This presentation will highlight how the integration of harmonized protocols and user-friendly technology can empower a global network of observers, providing the reliable data needed to support international environmental regulations and the fight against plastic pollution.