Basin-scale sources and pathways of microplastic that ends up in the Galápagos Archipelago

Abstract. The Galápagos Archipelago and Marine Reserve lies 1000 km off the coast of Ecuador and is among the world's most iconic wildlife refuges. However, plastic litter is now found even in this remote and iconic island archipelago. Prior to this study, the sources of this plastic litter on Galápagos coastlines were unidentified. Local sources are widely expected to be small, given the limited population and environmentally-conscious tourism industry. Here, we show that remote coastal sources of plastic pollution are also fairly localized and limited to South and Central American coastlines, in particular Northern Peru and Southern Ecuador. Using virtual floating plastic particles transported in high-resolution ocean surface currents, we analysed the backward-in-time and forward-in-time pathways and connectivity between the Galápagos region and the coastlines around the East Pacific Ocean. We also analysed how incorporation of wave-driven currents (Stokes drift) affects these pathways and connectivity. We found that only virtual particles that enter the ocean from Peru, Ecuador and (when waves are not taken into account) Colombia can reach the Galápagos. It takes these particles a few months to travel from their coastal sources on the American continent to the Galápagos region. The connectivity does not seem to vary substantially between El Niño and La Niña years. Identifying these sources and the timing and patterns of the transport can be useful for identifying integrated management opportunities to reduce plastic pollution from reaching the Galápagos Archipelago.