Microplastic Contamination of a Benthic Ecosystem in a Deep-Sea Hydrothermal Vent

Plastic contamination is a global pervasive issue, extending from coastal areas and open oceans to polar regions and even the deep sea. Microplastic contamination in hydrothermal vents, which are known for their high biodiversity even under their extreme conditions, has remained largely unexplored. Here, we present, for the first time, microplastic pollution in a deep-sea hydrothermal vent at one of the pristine biodiversity hotspots—the Central Indian Ridge. Not only the environment, (seawater: 2.08 ± 1.04 MPs/L, surface sediments: 0.57 ± 0.19 MP/g) but also all six major benthic species investigated were polluted by microplastics.  Microplastics mainly consisted of polypropylene, polyethylene terephthalate, and polystyrene fragments ≤ 100 µm, and were characterized as being either transparent or white in color. Remarkably, bioaccumulation and even biomagnification of microplastics were observed in the top predators of the ecosystem, such as squat lobsters (14.25 ± 4.65 MPs/individual) and vent crabs (14.00 ± 2.16 MPs/individual) since they contained more microplastics than animals at  lower trophic levels (e.g. mussels and snails, 1.75 ~ 6 average MPs/individuals). These findings reveal microplastic contamination of an ecosystem in a hydrothermal vent, thereby suggesting that their accumulation and magnification can occur in top-level animals even within remote and extreme environments.