Characterisation of the bacteria associated with barnacle, Balanus amphitrite, shell and their role in gregarious settlement of cypris larvae

► We investigated Balanus amphitrite associated bacteria with 16S rRNA-based methods ► Compared to biofilm on rock, barnacles hosted a higher ratio of alphaproteobacteria ► The effect on larval settlement of bacteria from barnacles and rocks was assessed ► It was found that barnacle-associated bacteria promoted larval settlement ► Vibrio and Pseudoalteromonas spp. are likely responsible for the promotory effect