Spatial heterogeneity of bacterial communities in the mucus of Montastraea annularis

Corals are known to contain a diverse microbiota; however, few studies have explicitly addressed the spatial variability of bacterial communities across individual, healthy coral colonies. This study applied culture-based and culture-independent methods to examine the spatial heterogeneity in bacterial communities in the mucus of 3 healthy Montastraea annularis colonies from Looe Key Reef, Florida Keys. Automated ribosomal intergenic spacer analysis (ARISA) results showed significant variability (up to 61% dissimilarity) in the composition of the total bacterial community at different locations only centimeters apart on individual coral colonies. Abundances of culturable Vibrio spp. determined by TCBS plating were highly variable across individual coral colonies, differing by up to 100-fold between different locations on the same colony. ARISA profiles indicated that intra-colony variation rivaled intercolony differences in the composition of the culturable Vibrio community (i.e. types of culturable Vibrio spp. and their relative abundances). The high degree of spatial heterogeneity in coral-associated bacteria observed across individual colonies has implications for coral microbiology studies and coral restoration projects.