Epibiont hydroids on beachcast <i>Sargassum</i> in the Mexican Caribbean

Abstract

Massive accumulations of pelagic species of <i>Sargassum</i> have generated recent social, economic and ecological problems along Caribbean shores. In the Mexican Caribbean, these events have prompted the study of diverse biological and ecological aspects of these macroalgae. However, studies on their associated biota, including Hydrozoa, remain scarce. This research provides important species observations in an area where data is lacking. The occurrence and percent cover of hydroids on <i>Sargassum</i> thalli collected on the beach at Puerto Morelos, Quintana Roo, Mexico from April 2018 to March 2019 was studied. Three pelagic species and morphotypes of <i>Sargassum</i> from this area were analyzed: <i>Sargassum fluitans</i> III, <i>S. natans</i> I and <i>S. natans</i> VIII, as well as a benthic species, <i>S. polyceratium</i> var. <i>ovatum</i>. A total of 14 taxa of hydroids, belonging to the superorders "Anthoathecata" and Leptothecata, were identified. In our study, more hydroid taxa were observed on axes of the different species of <i>Sargassum</i> than on leaves or aerocysts. In general, the greatest species richness of hydroids was observed from February to April. Results show that live hydrozoans attached to pelagic <i>Sargassum</i> are transported into the area. This should be considered in future management measures that address the recurring coastal abundance of <i>Sargassum</i> and its associated biota in the Caribbean region.