Peer Review #2 of "Gooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre (v0.1)"

Gooseneck barnacles (Lepas spp.) ingest microplastic debris in the North Pacific Subtropical Gyre Substantial quantities of small plastic particles, termed "microplastic," have been found in many areas of the world ocean, and have accumulated in particularly high densities on the surface of the subtropical gyres.While plastic debris has been documented on the surface of the North Pacific Subtropical Gyre (NPSG) since the early 1970s, the ecological implications remain poorly understood.Organisms associated with floating objects, termed the "rafting assemblage," are an important component of the NPSG ecosystem.These objects are often dominated by abundant and fast-growing gooseneck barnacles (Lepas spp.), which predate on plankton and larval fishes at the sea surface.To assess the potential effects of microplastic on the rafting community, we examined the gastrointestinal tracts of 385 barnacles collected from the NPSG for evidence of plastic ingestion.We found that 33.5% of the barnacles had plastic particles present in their gastrointestinal tract, ranging from one plastic particle to a maximum of 30 particles.Particle ingestion was positively correlated to capitulum length, and no blockage of the stomach or intestines was observed.The majority of ingested plastic was polyethylene, with polypropylene and polystyrene also present.Our results suggest that barnacle ingestion of microplastic is relatively common, with unknown trophic impacts on the rafting community and the NPSG ecosystem.