Macrolitter and microplastics along the East Pacific coasts - A homemade problem needing local solutions.

The East Pacific (EP) region, especially the central and southern EP, has been fairly less studied than other world's regions with respect to marine litter pollution. This comprehensive literature review (257 peer-reviewed publications) showed that both macrolitter (mostly plastics) and microplastics tend to accumulate on EP shorelines. Moreover, they were also reported in all the other compartments investigated: sea surface, water column, seafloor and 'others'. Mostly local, land-based sources (e.g., tourism, poor waste management) were identified across the region, especially at continental sites from low and mid latitudes. Some sea-based sources (e.g., fisheries, long-distance drifting) were also identified at high latitudes and on oceanic islands, likely enhanced by the oceanographic dynamics of the EP that affect transport of floating litter. Our results suggest that effective solutions to the problem require local and preventive strategies to significantly reduce the levels of litter along the EP coasts.

Plastic pollution transcends marine protected area boundaries in the eastern tropical and south-eastern Pacific.

The Eastern Tropical and South-Eastern Pacific region is of global biodiversity importance. At COP26, the governments of Costa Rica, Panama, Colombia, and Ecuador committed to the expansion of existing MPAs to create a new Mega MPA, safeguarding the Eastern Tropical Pacific Marine Corridor. It offers a profound step forward in conservation efforts but is not specifically designed to protect against the more diffuse anthropogenic threats, such as plastic pollution. We combine published data with our own unpublished records to assess the abundance and distribution of plastic pollution in the region. Macro- and microplastic concentrations varied markedly and were not significantly different when comparing areas inside and outside existing MPA boundaries. These findings highlight the diffuse and complex nature of plastic pollution and its ubiquitous presence across MPA boundaries. Understanding the sources and drivers of plastic pollution in the region is key to developing effective solutions.

Aerial and underwater drones for marine litter monitoring in shallow coastal waters: factors influencing item detection and cost-efficiency.

Although marine litter monitoring has increased over the years, the pollution of coastal waters is still understudied and there is a need for spatial and temporal data. Aerial (UAV) and underwater (ROV) drones have demonstrated their potential as monitoring tools at coastal sites; however, suitable conditions for use and cost-efficiency of the methods still need attention. This study tested UAVs and ROVs for the monitoring of floating, submerged, and seafloor items using artificial plastic plates and assessed the influence of water conditions (water transparency, color, depth, bottom substrate), item characteristics (color and size), and method settings (flight/dive height) on detection accuracy. A cost-efficiency analysis suggests that both UAV and ROV methods lie within the same cost and efficiency category as current on-boat observation and scuba diving methods and shall be considered for further testing in real scenarios for official marine litter monitoring methods.