Trashing our own "backyard" - Investigating dispersal and accumulation of floating litter from coastal, riverine, and offshore sources in the German Bight using a citizen science-based wooden drifter recapture approach.

Understanding marine debris dispersal through drift buoys and numerical modelling is one focus of litter pollution research that can identify particularly affected regions and aid targeted clean-up efforts. This study assessed the dispersal and accumulation of floating litter from coastal, riverine, and offshore sources in the German Bight, based on ~33,000 reports of wooden drifters deployed between 2016 and 2019. The majority (66.6%) released along the Lower Saxony coast and the rivers Ems, Weser, and Elbe were first reported within ≤25 km, indicating that coastal and riverine litter sources largely pollute adjacent shorelines. Drifters from coastal sites and release points near the river mouths dispersed similarly far, occasionally crossing distances comparable to those deployed at sea, reaching Scandinavia and Great Britain within a few days or weeks. Small-scale clustering occurred in <2% of all locations where drifters had been reported. These findings and limitations of the methodological approach are discussed.