Award: OCE-1829867

This award was a collaboration between Dr. Scott Burgess (Florida State University, FSU) and Dr. Peter Edmunds (California State University Northridge) to generate new knowledge on the fundamental mechanisms that determine the resilience, or lack thereof, of coral communities on tropical coral reefs. The field work component was based at the University of California Berkely Gump Station in Moorea, French Polynesia. The research integrated with, and added value to, the Moorea Coral Reef (MCR) Long-Term Ecological Research (LTER) site, also supported by the US National Science Foundation.

Coral reefs are an important source of food, income, medicine, and protection, but are globally in decline, which affects the US both directly and indirectly. Perhaps surprisingly, much of the biodiversity on coral reefs remains to be properly described so there is still much to learn about why some locations appear more resilient than others. Corals that look similar to each other but are genetically divergent because of different evolutionary histories are called cryptic species. Cryptic species are being increasingly discovered in many types of coral.

The intellectual merit of this work was the advance in knowledge for how cryptic coral species can, on the one hand create diverse portfolios in the capacity of biological communities to recover and reorganize after disturbance, and on the other hand reveal species with population sizes and geographic ranges that are smaller than previously thought with higher vulnerability to environmental change. We used modern genomic techniques to delineate six cryptic species of cauliflower coral (Pocillopora) and reveal their evolutionary relationships to each other, as well as to the suite of symbiotic algae hosted in the coral’s cells. In 2019, there was a severe marine heatwave that caused about 70% of the corals to die at Moorea. Larger corals bleached and died more than smaller corals, leading many to conclude that coral size mediates bleaching. Our research discovered that one particular species (genetically identified), which was also quite common and had large colony sizes, suffered much higher mortality than the other five species. As a result, we were able to show that differences in coral bleaching and mortality were explained by different tolerances among cryptic species, and not the size of the coral. This discovery led to a fundamentally different interpretation of the mechanisms explaining why some corals bleach while others do not. We also discovered that different cryptic species prefer to live in different habitats within the reef. Such niche partitioning is important because it sheds light on how cryptic species diverged evolutionarily, how they coexist without outcompeting each other, and how restoration initiatives should consider the location and choice of corals to focus on. We also performed a series of aquarium experiments that showed how cryptic species have different physiological responses to environmental factors like temperature and light, both of which differ among habitats and are changing over time. Overall, this project has changed the way researchers study cauliflower corals, shown how cryptic coral species affect ecological processes that are relevant beyond corals, and positioned the research community, including the MCR LTER, to pursue new research questions and directions. The project has produced 11 peer-reviewed papers so far, many as open access.

The results of this research had broader impacts that were directly relevant to management decisions and restoration initiatives because the project generated new knowledge of the species diversity within the main type of reef building coral, uncovered how different habitats within coral reefs contain different cryptic species, and revealed that marine heatwaves affect some cryptic species but not others. The project contributed to STEM education by supporting three PhD students and two undergraduate students. The project contributed to developing a competitive STEM workforce by mentoring one postdoctoral scholar and four research technicians. The project increased participation of the best and brightest in STEM by training and mentoring six women and two people from an underrepresented group. One student from the latter group was also supported with supplemental funding (INTERN) to do a non-academic research internship at the NOAA Southwest Fisheries Science Center. The internship provided training and professional development to expand the student’s preparation for a wider range of career paths after graduation. There were also numerous public engagement activities including communicating results via public lectures at local libraries, and by press releases and news articles of key findings. We also described a new species of Pocillopora at Moorea, and deposited a specimen at the Smithsonian National Museum of Natural History. We worked with FSU Research to produce a 3-minute video describing our research results for the general public. To communicate our research internationally, we made a version with French subtitles, and another version with Tahitian subtitles and voice.

Last Modified: 04/17/2025
Modified by: Scott Burgess