Break-through fish diversity and locations

Aim: While marine debris is entering the ocean at unprecedented rates, little is known about how biological communities engage with this introduced substrate. This study analyzes the community composition of debris-associated fishes and explores the role of plastics in transferring fish across biogeographic barriers.

Location: Pacific Ocean, including North Pacific Garbage Patch.

Results: Fish communities around marine debris have low diversity, individual debris items have highly dissimilar species compositions, and species composition is affected by horizontal debris item size. Debris items in Group I have significantly higher fish species diversity and differ in community composition from Group II. We observed four species (Abudefduf vaigiensis, Histrio histrio, Oplegnathus punctatus, and Petroscirtes spp.) surviving east of the Hawaiian Islands, where they have not been previously reported. While we have not yet detected juveniles of these "break through" species east of the Islands, the earlier transport by debris of A. vaigiensis and H. histrio to Hawaii in the 1990s and their subsequent successful establishment there suggest that these Indo-Pacific fish have found hospitable thermal regimes east of the Hawaiian Islands matching their original reproductive ranges.

Main conclusion: We suggest that marine debris acts as a mechanism for fish to cross biogeographic barriers, such as the Eastern Pacific Barrier. While natural flotsam has long been a potential vector, long-lived and increasingly abundant plastic debris may set the stage for altering fish biogeography.