FSLEs help in modelling marine floating debris accumulation

Floating marine debris (FMD) pollution, including mostly plastics, has negative impacts on marine environments. Their accumulation is a major concern, particularly in coastal areas, where a better understanding of the processes involved would be crucial for coastal management to target interventions. Frontal zones are considered to act as aggregators of floating marine debris, but they are also biogeochemical hotspots, which also aggregate marine organism, thus increasing the debris' impact on marine organisms.

To observe the fronts, and model floating marine debris accumulation, fine-resolution SST data, as well as bathymetry, current velocities and Finite-size Lyapunov exponents (FSLEs) were used in a study by the University of Tasmania. The study area was selected within the Gulf of Maine and Nantucket Shelf area on the northeast coast of the United States of America (USA), due to the availability of floating marine debris data there. The interactions of tidal mixing, the Eastern Maine Coastal Current and bottom topography are the primary factors generating the five main coastal fronts found in this area. In three of those front, debris accumulations are observed.

The study concludes that both fronts and the physical processes which form them (frontogenesis) influence the accumulation of floating marine debris in the area of study. The modelling shows that the environmental variables used, including FSLES (except for bathymetry) have an impact on the accumulation and could be used for forecasting. Further sampling campaigns in different coastal environments should be led to validate and improve the process.