Turtle barnacle in the plastisphere: an unusual attachment of Chelonibia testudinaria to marine plastic debris

Abstract Marine plastic debris is transforming ecological boundaries in the Anthropocene. A rare attachment of the epibiotic barnacle, Chelonibia testudinaria , to floating plastic debris is reported here. Traditionally considered host-specific to marine vertebrates, this finding challenges the strict biological dependence of this species. The barnacle was firmly cemented to an artificial polymer, co-occurring with the coastal fouler Amphibalanus amphitrite . This observation suggests that marine plastics may serve not only as passive transport vectors but also as novel settlement substrates for host-associated epibionts, and that C. testudinaria may occasionally settle on artificial substrates under natural conditions.