Healthy and SCTLD-diseased corals in mesocosms

Each of the two mesocosms shown contains filtered and UV-treated seawater, a weighted airline (for water circulation and oxygenation), and a fragment of a coral colony. In both corals, the brown region represents apparently healthy, non-necrotic coral tissue. In the left mesocosm, the coral is healthy with no apparent signs of disease. In the right mesocosm, the coral is infected with stony coral tissue loss disease (SCTLD) and is displaying characterisitc disease lesion in the lower left corner. The white area is recently exposed dead coral skeleton, where tissue has been lost due to the disease. The green area is coral skeleton that has been exposed by SCTLD and is now being overgrown by algae.