On healthy reefs around the world, corals, algae, fishes and microbes live interconnected and in balance—exchanging nutrients, resources, and chemical signals. However, new research led by the University of Hawai'i (UH) at Mānoa and the Royal Netherlands Institute for Sea Research (NIOZ) has revealed that when coral bleaching occurs, corals release unique organic compounds into the surrounding water that not only promote bacterial growth overall, but select for opportunistic bacteria that may further stress reefs.