Spatial heterogeneity of bacterial communities in the mucus of Montastraea annularis

Abstract

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 hetero- geneity 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 Vib- rio 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 commu- nity (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.