Exploring the role of macroalgal surface metabolites on the settlement of the benthic dinoflagellate Ostreopsis cf. ovata.

We investigate in this work the surface chemistry of four brown algae of the Dictyotaceae family as a potential factor for the settlement of the toxic benthic dinoflagellate O. cf. ovata. While the interactions between bacteria and macroalgae have been investigated to some extent during the past decades, less is known about the drivers guiding the settlement of microalgae on the surface of macroalgae. An integrative approach combining 18S rRNA sequencing, untargeted metabolomics and in vitro bioassays was used to analyze the epiphytic microbial communities as well as the surface chemotype of each macroalgal species together with the bioactivity of their surface metabolites.