Abstract: I will present some findings showing genetically-identified cryptic coral species within a functional group differing in their response to disturbance (bleaching), environmental gradients (depth), and symbiont community. These findings suggest a role for response diversity in driving ecological resilience at Moorea, but also highlight the vulnerability of previously unrecognized populations that are smaller than expected based on morphological classifications of ‘species’. At Moorea, broadcast-spawning Pocillopora corals dominate the reef and species are notorisouly difficult to reliably to tell apart in the field. As a result, researchers in the past typically grouped them according to morphology, which hides evolutionarily distinct genetic lineages. In 2019, coral bleaching occurred at Moorea. What looked like larger colonies bleaching and dieing more than smaller colonies turned out instead to be differences among at least five cryptic species. While not all species died from bleaching, the specific genetic lineage in which most colonies died happened to have larger colonies and has so far only been found at Moorea. The bleaching event was caused by a sub-surface heatwave, governed by a reduction in cooling from internal waves. As a result, the 2019 marine heatwave at Moorea was completely missed by satellite-derived estimates of sea surface temperature and degree heating weeks, which are commonly used to monitor thermal stress on coral reefs.

Biography: Scott Burgess is an Associate Professor at Florida State University (FSU). Research in his lab group combines ecological and evolutionary principles to study the population biology of coastal marine invertebrates (mostly corals and bryozoans). He has been working on coral reefs for about 20 years, beginning with a formative JCU Honors project at One Tree Island on larval fish dispersal. Since then he worked at AIMS in the LTMP, then did a PhD at UQ, then moved to the US to do a Postdoc at UC Davis. He has been at FSU since 2014, and does field work at Moorea, French Polynesia. He is broadly interested larval dispersal, reproductive strategies, and adaptation to variable environments. He typically uses some combination of field and laboratory experiments, molecular genetic approaches, and mathematical modeling.