Bottom-Feeders Eat Their Fiber: Ingestion of Anthropogenic Microdebris by Antarctic Deep-Sea Invertebrates Depends on Feeding Ecology

Anthropogenic debris has been documented in Antarctica for the past 40 years. Upon breakdown, large pieces become microdebris, which reaches the seafloor through a variety of physical and biological processes. The Antarctic benthos, deeply reliant on sinking organic particles, is thus vulnerable to ingesting microdebris. By using benthic specimens sampled between 1986 and 2016 and deposited in biological collections, we provide the first record of microdebris in Southern Ocean deep-sea invertebrates. Specimens from 15 species (n = 169 organisms) had their gut content examined, with 13 species yielding microdebris in the shape of fibers (n = 85 fibers). The highest ingestion percentages were recorded in the sea cucumbers <i>Heterocucumis steineni</i> (100%), <i>Molpadia violacea</i> (83%) and <i>Scotoplanes globosa</i> (75%), and in the brittle star <i>Amphioplus peregrinator</i> (53%). Deposit- and suspension-feeding were the strategies which yielded the most fibers, accounting for 83.53% of particles. Seven fibers were identified as microplastics, composed of polyamide, polycarbonate, polyester, polyethylene terephthalate, polyisoprene and polysulfone. We also provide the earliest record of a microplastic in Antarctica, a polysulfone fiber ingested by a <i>Boreomysis</i> sp. mysid caught in 1986. The occurrence of fibers in the world's most remote continental margin renews concerns of pollution in seemingly isolated regions.