can be found in places as wide ranging as the cold, nutrient-rich, upwelling-fueled waters of the Eastern Pacific, the calm waters of the Society Islands in the South Pacific (where I took this photo), and the crystal clear, positively balmy waters of the Red Sea, from whence I am writing this post. Most taxonomists place individuals from either end of their range into the same species, but at some point that is an arbitrary decision. There are clear physiological differences within coral species that are correlated with geography. If you transplanted a colony of Pocillopora damicornis from Panama to Saudi Arabia, the elevated water temperatures would almost certainly cause it to bleach and die. Why? Dunno. Some researchers, such as the Meyer lab at OSU, are trying to figure that out by looking at genetic differences in the corals. Others suggest that corals can gradually acclimate to such extremes in temperature. We think those hypotheses are part of the story, but that the microbes that live with corals might tell another important part. After all, the interactions with microbes through disease and bleaching are the most common causes of coral death. If we compare the differences in microbes across a host species’ range of environments to the differences explainable by the coral’s evolutionary history, we might be able to explain why some corals are more tolerant of variation in the environment than others.
As I procrastinate on my mountains of queued labwork, I am happily organizing and editing my photos from the field. We have photographed each sampled coral colony, hoping to use the collection as a backup for the metadata that we collected simultaneously. The photo at the top of the page depicts the last coral we sampled on this trip – one that had me pumping my fists underwater in excitement! It’s not a particularly rare species, but Jesse and I had a long wish list, a short span of time, and a limited number of reefs to explore. In order to describe the broad levels of variation in the coral microbiome, we are trying to sample at least two species from each coral family we come across, in each location. After we visit a number of reefs around the world, we hope to have enough replication within each family to describe how they differ from one another. As our tanks of air slowly got lower on gas, we still hadn’t found a symbiont-bearing representative of the Dendrophylliidae, though we knew it was around here somewhere! Just as I had given up on it, I spotted that yellow rock. And to be honest, the excitement I felt at that moment is the real reason that I do what I do.