We show that the high seas are colonized by a diverse array of coastal species, which survive and reproduce in the open ocean, contributing strongly to its floating community composition. Analysis of rafting plastic debris in the Eastern North Pacific Subtropical Gyre revealed 37 coastal invertebrate taxa in total, largely of Western Pacific origin, exceeding pelagic taxa richness by three-fold. Coastal taxa, including diverse taxonomic groups and life history traits, occurred on 70.5% of debris items. Most coastal taxa possessed either direct development or asexual reproduction, possibly facilitating long-term persistence on rafts. Our results suggest that the historical lack of available substrate limited colonization of the open ocean by coastal species, rather than physiological or ecological constraints as previously assumed. It appears that coastal species persist now in the open ocean as a substantial component of a neopelagic community sustained by the vast and expanding sea of plastic debris.

Please see Haram et al. 2023 Nature Ecology and Evolution for details: https://www.nature.com/articles/s41559-023-01997-y