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

Abstract

Abstract. The Galápagos Archipelago and Galápagos Marine Reserve lie 1000 km off the coast of Ecuador and are among the world's most iconic wildlife refuges. However, plastic litter is now found even in this remote 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 sources of plastic pollution are also fairly localised and limited to nearby fishing regions and South American 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 plastic origin and fate using pathways and connectivity between the Galápagos region and the coastlines as well as known fishery locations 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 region. 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.

Microplastic pollution in seawater and marine organisms across the Tropical Eastern Pacific and Galápagos

“…1 ). These findings are coherent with basin-scale microplastic particles transport that explain sources and pathways of microplastic that end up in the Galápagos Archipelago 30 from far South oceanic basins. However, Costa Rica and other countries farther north can be considered as plastic particle origin sources if simulations are not limited to surface currents.…”

“…Around 60% of all plastic items produced are less dense than seawater 3 . Biofouling and other interactions with marine biota, degradation, fragmentation or additives leaching may accelerate the sinking process of derived plastic particles 30 . The impact of microplastics in the marine environments, however, depends on physical behaviours (migration, sedimentation and accumulation), chemical behaviours (degradation and adsorption) and bio-behaviours (ingestion, translocation and biodegradation) 18 .…”

“…However, plastic litter and microplastic residues have recently been found even in this isolate group of islands and around its waters. To our knowledge, prior to this study, the levels of this microplastic contamination and its quantification on Galápagos coastlines and across the Eastern Tropical Pacific were barely known and limited to one single study 30 .…”

“…As surface ocean currents are spatial and temporal variables, the highest concentrations of plastic debris are constantly fluctuating. However, there is limited available data on the sources and dispersion of plastic litter along the Tropical South American coast and the Galápagos archipelago 30 .…”

Object narratives as a methodology for mitigating marine plastic pollution: multidisciplinary investigations in Galápagos

“…Specifically, modelling by van Sebille et al . (2019), using virtual plastic particles (Lange & van Sebille 2017), suggests that plastic waste from outside the archipelago itself originates predominantly from northern coastal Peru and southern Ecuador, with the strong probability of additional material coming from fishing fleets in the vicinity of the archipelago, whose presence and movements are now tracked by satellite. In the case of Galápagos, therefore, plastic pollution appears to be a regional problem, requiring regional solutions.…”