Star Coral (IMAGE) Penn State Caption Physiologically stressed reef corals lose their symbionts and appear bleached. The invasive symbiont, Symbiodinium trenchii is quick to populate these animals after cessation of thermal stress. Credit Dustin Kemp, University of Georgia Usage Restrictions Non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.