Bacterial diseases are on the rise in tropical corals, causing a decline in coral populations across the globe. Researchers around the world have determined which bacteria cause coral disease and how disease spreads across reefs. However, we actually still know very little about what types of bacteria are in healthy corals. Recent experiments suggest that like humans, corals maintain beneficial bacteria in and on their tissues. Here at OGL, the main focus of our coral microbiology research program is the characterization of bacterial communities in healthy corals. We believe that basic research on the role of bacteria in coral health is critical for effective management of precious coral reef resources, including the Florida Keys and the Hawaiian Islands, not to mention reefs around the world.
Scientists at OGL work with corals at their earliest stages – eggs, sperm, and larvae. By studying bacteria in young corals, we are determining how and when coral-bacterial associations are initiated, whether or not there are specific bacteria that live within corals, and how stable those relationships are across time and space. We use DNA-based analysis and advanced microscopy to identify bacteria in these early life stages of corals. Our research has shown that mass spawning corals are colonized by bacteria after the larval stages settle and metamorphose into juvenile polyp stages. We have also identified particular groups of bacteria that may be very important to Caribbean corals, and a group of bacteria that are passed from parent to offspring in one coral species.
Like our research on shipworm symbiosis, our work on the elaborate relationships between corals and bacteria reminds us that it is important to understand, protect, and preserve even the smallest organisms. We are certain that our research will shed some light on the processes controlling bacterial infection and colonization of corals, and how bacteria contribute to coral health.