From the Sea to the Land: Dynamic of the Sargassum Tide Holobiont in the Caribbean Islands Pascal Jean Lopez (
[email protected] ) CNRS Délégation Paris B https://orcid.org/0000-0002-9914-4252 Vincent Hervé Max-Planck-Institut for Terrestrial Microbiology Josie Lambourdière Centre National de la Recherche Scientique Malika René-Trouillefou Universite des Antilles et de la Guyane Damien Devault Centre National de la Recherche Scientique Research Keywords: Macroalgae, Methanogenic archaea, Sulfate-reducing bacteria, Epibiont, Microbial communities, Nematodes, Ciliates Posted Date: June 9th, 2020 DOI: https://doi.org/10.21203/rs.3.rs-33861/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 1/27 Abstract Background Over the last decade, intensity and frequency of Sargassum blooms in the Caribbean Sea and central Atlantic Ocean have dramatically increased, causing growing ecological, social and economic concern throughout the entire Caribbean region. These golden-brown tides form an ecosystem that maintains life for a large number of associated species, and their circulation across the Atlantic Ocean support the displacement and maybe the settlement of various species, especially microorganisms. To comprehensively identify the micro- and meiofauna associated to Sargassum, one hundred samples were collected during the 2018 tide events that were the largest ever recorded. Results We investigated the composition and the existence of specic species in three compartments, namely, Sargassum at tide sites, in the surrounding seawater, and in inland seaweed storage sites. Metabarcoding data revealed shifts between compartments in both prokaryotic and eukaryotic communities, and large differences for eukaryotes especially bryozoans, nematodes and ciliates.