The Aura-biome

Benthic organisms influence the microbes in the surrounding water layer, which we have termed the aura-biome.

The types of microbes in the water column are correlated with benthic cover (Kelly et al 2014). Therefore, we hypothesize that the microbiome in the boundary layer just above a benthic organism will be influenced by that organism. We investigated whether a patch of reef dominated by single reef organisms influenced the types of microbes in the water directly above the organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including 1) the coral Mussismilia braziliensis, 2) fleshy macroalgae (Stypopodium, Dictota and Canistrocarpus), 3) turf algae, and 4) the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef.

Each benthic macro-organism influences the taxa and functions of microbes in the water column surrounding it, developing a specific “aura-biome”. The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria, Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity. Zoanthids, which are highly invasive and form large monocultures were associated with Alteromonas and functions suggesting a stressful environment.
Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water column, which may lead to either the stimulation or suppression of the recruitment or growth of neighboring benthic organisms.

Read more in Walsh et al 2017 in PeerJ.