Marine biofouling organisms on beached, buoyant and benthic plastic debris in the Catalan Sea

11 pages, 7 figures, 4 tables

Plastic debris provides long-lasting substrates for benthic organisms, thus acting as a potential vector for their dispersion. Its interaction with these colonizers is, however, still poorly known. This study examines fouling communities on beached, buoyant and benthic plastic debris in the Catalan Sea (NW Mediterranean), and characterizes the plastic type. We found 14 specimens belonging to two phyla (Annelida and Foraminifera) on microplastics, and more than 400 specimens belonging to 26 species in 10 phyla (Annelida, Arthropoda, Brachiopoda, Bryozoa, Chordata, Cnidaria, Echinodermata, Mollusca, Porifera and Sipuncula) on macroplastics. With 15 species, bryozoans are the most diverse group on plastics. We also report 17 egg cases of the catshark Scyliorhinus sp., and highlight the implications for their dispersal. Our results suggest that plastic polymers may be relevant for distinct fouling communities, likely due to their chemical structure and/or surface properties. Our study provides evidence that biofouling may play a role in the sinking of plastic debris, as the most abundant fouled plastics had lower densities than seawater, and all bryozoan species were characteristic of shallower depths than those sampled. More studies at low taxonomic level are needed in order to detect new species introduction and potential invasive species associated with plastic debris

BF was supported by the postdoctoral fellowships programme Beatriu de Pinós funded by the Secretary of Universities and Research (Government of Catalonia) and the Horizon 2020 programme of research and innovation of the European Union under the H2020 Marie Skłodowska-Curie Actions grant agreement no. 801370 (Incorporation grant 2019 BP 00183), and by the Juan de la Cierva programme funded by the Ministry of Science and Innovation (Incorporation grant IJCI-2017-31478). EDM was supported by the European Research Council (ERC) under the European Union's Horizon 2020 - Research and Innovation Framework Programme (grant agreement no. 724324 to L.H. Liow) and the Research Council of Norway (grant 314499 to E. Di Martino). This research has received support through a Catalan Government Grups de Recerca Consolidats grant to GRC Geociències Marines (ref. 2017 SGR 315) and the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) to Institut de Ciències del Mar

Peer reviewed