Marine Benthic Invertebrates 16S rRNA gene pyrotag

Coral reefs provide habitat for an array of marine invertebrates that host symbiotic microbiomes. Photosynthetic symbionts including Symbiodinium and diatoms potentially influence the diversity of their host-associated microbiomes by releasing carbon-containing photosynthates and other organic compounds that fuel microbial metabolism. In this study we used 16S rRNA gene amplicon pyrosequencing to characterise the microbiomes of 11 common Great Barrier Reef (GBR) marine invertebrate species that host photosynthetic symbionts and five species in which photosynthetic symbionts are absent. The presence of photosynthetic symbionts influenced the composition but not the species richness, evenness and phylogenetic diversity of invertebrate-associated microbiomes. Invertebrates associated with non-photosynthetic symbionts were dominated by Alphaproteobacteria while those hosting photosynthetic symbionts were dominated by Gammaproteobacteria. Interestingly many sequences retrieved from symbiont bearing invertebrates, for example Oceanospirillales spp., Alteromonas spp., Pseudomonas spp., Halomonas spp., have previously been implicated in the metabolism of the organic sulfur compound dimethylsulfoniopropionate (DMSP), produced in high concentrations by photosymbiont dinoflagellates and implicated in climate regulation through facilitating cloud formation. This study highlights the complex nature of invertebrate holobionts and confirms the importance of photosynthetic symbionts in structuring marine invertebrate-associated bacterial communities.