The case study of Israel and Portugal

This work was supported by the Israel Ministry of Science and Technology Israel-Portugal collaboration grant (3–1650). Funding Information: The authors are grateful to Maxim Rubin-Blum and Mali Salmon-Divon for scientific advice. The authors thank “ecoocean” non-profit organization for providing the Israeli research vessel and the crew. The authors acknowledge the collaboration of the Institute for Nature and Forests Conservancy (ICNF), in particular Ana Sofia Palma and the Nature Wardens, Carlos Silva known as “Lobo do Mar,” Inês Nobre and André Silveira for operating the boat and helping to collect samples in Sado. The authors express gratitude to the MARLab team of the NOVA School of Science and Technology, especially Andreia Guilherme, João Pequeno, and other volunteers who helped in field work, and also thank Isabel Menezes from the Portuguese Institute for the Ocean and Atmosphere (IPMA), for granting access to the Folsom splitter. Publisher Copyright: Copyright © 2023 Marsay, Ambrosino, Koucherov, Davidov, Figueiredo, Yakovenko, Itzahri, Martins, Sobral and Oren.Introduction: Floating microplastic debris are found in most marine environments around the world. Due to their low density and high durability, plastic polymers such as polyethylene, polypropylene, and polystyrene serve as stable floating substrates for the colonization of diverse communities of marine organisms. Despite the high abundance of microplastic debris in the oceans, it is not clear how the geographical location and season affect the composition of marine microplastic and its bacterial microbiome in the natural environment. Methods: To address this question, microplastic debris were collected from the sea surface near estuaries in the Mediterranean Sea (Israel) and in the Atlantic Ocean (Portugal) during summer and winter of 2021. The microplastic physical characteristics, including shape, color, and polymer composition, were analyzed and the taxonomic structure of the microplastic bacterial microbiome was characterized using a high-resolution metabarcoding pipeline. Results: Our results, supported by previously published data, suggest that the plastisphere is a highly diverse ecosystem which is strongly shaped by spatial and temporal environmental factors. The geographical location had the highest impact on the plastisphere physical characteristics and its microbiome composition, followed by the season. Our metabarcoding analysis showed great variability between the different marine environments with a very limited microbiome “core.” Discussion: This notion further emphasizes the importance of plastisphere studies in different geographical locations and/or seasons for the characterization of the plastisphere and the identification of plastic-associated species.publishersversionpublishe