Physiological Comparison of Bacterial Communities From Various Species of Scleractinian Corals

Ritchie, K.; Smith, G.

Bacterial communities within the surface layers of hard corals have been shown to play an important nutritional role for the coral animal. They may play an equally important role in maintaining the health and preventing disease in corals. However, very little is known about the composition of the 'normal microbiota' in the furface mucopolysaccharide layers of these animals. We attempted to address this problem by comparing carbon source utilization patterns of the bacterial communities from surface mucopolysaccharide layers. Each community was seperately exposed to 95 potential carbon sources. Oxidation rates were measured every six hours for a 72 hour period. Most amino acids were oxidized by all bacterial communities. Oxidation of some carbohydrates and organic acids were highly variable. These were used to compare communities from the different sources. Cluster analysis showed that communities from the boulder corals grouped together (Montstrea spp., Diploria spp., and Dichocoenia sp.) and Acropora palmata clustered with Porites spp.. The Agaricia agaricites bacterial community was not similar to those of other corals. Finally, the bacterial community from the water mass was not similar to coral bacterial communities as a whole. These results indicate that corals may have a distinct microbiota characteristic of a coral type. Continuing studies should help maximize the level of resolution of these communities within specific coral species.

Physiological Comparison of Bacterial Communities From Various Species of Scleractinian Corals

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