Spatial, temporal and network analyses provide insights into the dynamics of the bacterial communities associated with two species of Caribbean octocorals and indicate possible key taxa.

Despite the current decline of scleractinian coral populations, octocorals are thriving on reefs in the Caribbean Sea and western North Atlantic Ocean. These cnidarians are holobiont entities, interacting with a diverse array of microorganisms. Few studies have investigated the spatial and temporal stability of the bacterial communities associated with octocoral species and information regarding the co-occurrence and potential interactions between specific members of these bacterial communities remain sparse. To address this knowledge gap, this study investigated the stability of the bacterial assemblages associated with two common Caribbean octocoral species, Eunicea flexuosa and Antillogorgia americana, across time and geographical locations and performed network analyses to investigate potential bacterial interactions. Results demonstrated that general inferences regarding the spatial and temporal stability of octocoral-associated bacterial communities should not be made, as host-specific characteristics may influence these factors. In addition, network analyses revealed differences in the complexity of the interactions between bacteria among the octocoral species analyzed, while highlighting the presence of genera known to produce bioactive secondary metabolites in both octocorals that may play fundamental roles in structuring the octocoral-associated bacteriome.

Supplementary information: The online version contains supplementary material available at 10.1007/s13199-023-00923-x.