Diversity and distribution of the coral-associated endolithic algaeOstreobiumin the Southwestern Caribbean

Abstract

AbstractCoral reefs are facing significant environmental challenges. Ocean acidification has the potential to induce the dissolution of coral reefs. The community of micro-bioerosion exhibits a heightened level of concern in the context of ocean acidification. Comprehending the close interplay between bioeroders and corals is of utmost importance in predicting the trajectory of these vulnerable ecosystems. The genusOstreobium, which belongs to the order Bryopsidales (Chlorophyta) and comprises euendolithic chlorophyte algae, has been identified as the primary cause of reef dissolution among microbioeroders. The objective of this study was to comprehend the inherent distribution ofrbcLclades ofOstreobiumin the Southwestern Caribbean corals within a gradient of reef depth. TheOstreobium rbcLvariants were found to be linked with corals belonging to the Agariciidae, Merulinidae, Poritiidae, Siderastreidae, Astroconeiidae, Montastreidae, Mussidae, and Pocilloporidae families. The individuals selected for the current investigation are categorized as members of either the “complex” or “robust” coral groups. Our findings indicate that solely the corals categorized as ‘complex’ exhibit close memberships with the threeOstreobiumsuperclades. In general, the dispersion ofOstreobiumwithin the Southwestern Caribbean region exhibits differentiation among various coral groups and is influenced by geographical and bathymetric factors. TheOstreobium’s diversity is primarily composed of ecological specialists, wherein most clades are linked to particular hosts. Conversely, only a few ecological generalists are associated with multiple hosts, akin to zooxanthellae.Ostreobiumexhibits greater diversity on encrusting corals such as agariciids, which are among the most abundant and widespread coral species in the Caribbean.