For millennia, coral reefs have flourished as one of the planet's most magnificent natural wonders. As Earth's most biodiverse ecosystem-surpassing even the rainforests-they are home to a cooperative network ranging from immense fish to sunlight-capturing algae to invisible microbes. Just how critical the microbes in particular are for coral reef health is finally understood thanks to recent discoveries. Coral Reefs in the Microbial Seas is the first book to unveil the complete story of how these relationships uphold coral reef health and what impact human activity has on this delicate balance.