Diagram of waterborne coral disease investigation method

A synopsis of our method for investigating waterborne coral disease. Some coral diseases, such as stony coral tissue loss disease, are known to be waterborne, meaning that pathogen(s) are shed by infected corals into the surrounding water column and spread to other corals. Our approach uses diseased corals placed into mesocosms containing sterile seawater, which then infuse the water with the unknown pathogen(s). Because the infectious dose needed to infect healthy corals is not known, our method involves concentrating the sample via tangential flow filtration (TFF). Mesocosm water is passed through a mesh screen to remove any large debris, then passed over a series of 100 kDa filter cassettes using a peristaltic pump. Through this process, pure water is filtered out of the sample, while any microbes are retained, gradually concentrating the microbial community present in the mesocosm in a small volume of water. Because different microbial groups (e.g. bacteria, viruses, etc) largely can be grouped by size, this concentrate is then passed through a series of different pore size filters to capture different size classes of the microbial community. These filters can then be investigated using targeted sequencing approaches, or could be used in transmission experiments to identify the size class, and by association the likely microbial group, that is responsible for causing the coral disease.