Award: OCE-1503430

The back-to-back mass coral bleaching events of 2014 and 2015 represented an unprecedented natural experiment that allowed researchers to examine the impacts of multiple large-scale disturbances on the response of the threatened staghorn coral, Acropora cervicornis, to thermal stress in Florida, US. Both in terms of bleaching susceptibility of wild colonies (75% of colonies showed signs of bleaching in 2014 and 63% in 2015) and colony mortality (88% of colonies died in 2015), staghorn corals proved to be very vulnerable to these thermal anomalies where sea temperatures exceeded 32 °C for prolonged periods of time. The initial impacts of the bleaching were exacerbated by the occurrence of a "Rapid Tissue Loss" coral disease that resulted in additional coral mortality. The negative responses recorded are a source of concern for a coral species that was recently listed as threatened under the US Endangered Species Act due to its drastic regional decline. While the impacts observed in Florida were significant, the variable response of different coral genotypes, ranging from 0-100% bleaching, showed that there are certain genotypes that are indeed resilient to increased temperatures and are thus able to survive even extreme sequential bleaching events. The identification of these resilient genotypes is a major finding of this study and this information will be used directly by researchers and resources managers to design effective restoration activities that include the propagation and outplanting of these hardy types into susceptible reef environments. The next step of our research is to investigate further the factors that make surviving corals resilient to bleaching. To address this important question, our project collaborators will be analyzing coral tissue samples collected before, during, and after both bleaching events to evaluate the role that nutritional status and the identity of symbiotic microalgae and microbes may have on the differential response of coral genotypes. The information collected in this study was incorporated into the Tropical Ecology Curriculum taught by the project investigators to undergraduate and graduate students at the University of Miami and Florida International University. In addition, public lectures on the causes and impacts of coral bleaching were incorporated into the workshops and lectures offered to local schools and the public as part of our Rescue-A-Reef Citizen Science Program (http://sharkresearch.rsmas.miami.edu/donate/rescue-a-reef). Last Modified: 01/29/2016 Submitted by: Diego Lirman