Plastic bottle caps act as vessels for invasive species in ocean drift

A research team led by Nagoya University and Fukui Prefectural University has discovered that small pieces of marine debris, such as plastic bottle caps, can act as “small ships” for various organisms, potentially facilitating the introduction of invasive species into new ecosystems.

In January 2023, researchers recovered a 3.5-centimeter plastic bottle cap off the coast of Kochi Prefecture, Japan. The cap, which bore a label from a beverage company in the Philippines, contained a complex micro-ecosystem of 307 individuals, including polychaetes, bryozoans, barnacles, and foraminifera. Notably, some of the polychaetes identified had not been previously recorded in Japan.

Through drift simulations and analysis of foraminifera shells, the team estimated that the cap traveled from the northern Philippines to the waters off Kochi via the Kuroshio Current, a journey lasting at least 70 days. The study, published in the journal “Marine Pollution Bulletin”, highlights that marine plastic pollution poses a threat to biodiversity not only through ingestion and landscape degradation but also by serving as a transport mechanism for non-native species.