Coral reefs have the highest biodiversity of any marine ecosystem. I’ve always been fascinated by all of the critters present on reefs, and have wondered how communities are assembled, both in space and in time. We (that is, the public, as well as research scientists) immediately think about swarms of colorful fishes and complex networks of corals when we think about reefs. However, there is another level of biological complexity on coral reefs. This is the microbial communities found living on and near corals.
Corals are unique animals in that they are intimately associated with both their constituent microbial communities and the zooxanthellae that live in the coral tissue. These three components – the coral, the zooxanthellae, and the microbes – make up the coral holobiome. With the advent of next generation sequencing it is possible to characterize the entire community of microbes living on and in association with corals. This allows testing of classic hypotheses related to community assembly. Because the microbial community is intimately associated with the host coral, inferred patterns and processes can “scale up” to the level of the host.