Award: OCE-2048678

Reef-building corals serve as the foundation for coastal ecosystems in the tropics, and as global temperatures rise, corals are adapting to environmental stress. This project investigated the mechanisms of thermal tolerance among Porites lobata corals in Palau. We found that corals use multiple strategies to withstand stress - genetic adaptation of the corals themselves, genetic adaptation of their symbionts, and control of their microbial communities. In some cases, there is a trade-off between a coral's ability to tolerate high temperatures and their ability to tolerate light stress. These results show how corals respond to environmental stress and helps predict how corals will continue to adapt to a changing global climate. 

A critical question for this research was whether the corals that have adapted to high temperatures can produce offspring that survive on other reefs. In Palau, semi-enclosed lagoons have high water temperatures on a daily basis, so the corals that live in the lagoons are adapted to those high temperatures. If corals outside the lagoons (with lower thermal tolerance) bleach or die, could larvae from the thermally-adapted lagoon corals re-seed those outer reefs and help incresae the ability of all corals to withstand future bleaching events? To answer this question, we spawned Porites lobata corals in a labooratory environment, raised the larvae to settlement, and then planted the newly-settled corals (from thermally tolerant parents) at their home reef in a lagoon and at another reef outside the lagoon. There was no difference in survival between corals planted at their home reef or at the away reef. A lab experiment with newly-settled corals showed that light stress is more lethal to newly-settled corals than thermal stress. Together, these results show us that some thermally-tolerant corals from the lagoons might survive on the outer reefs, but the trade-off between thermal tolerance and light tolerance might cause mortality of some corals. Our team was the first to successfully spawn and rear Porites lobata larvae in a lab, so our results will lay the foundation for future research and restoration efforts using this species. 

This project supported training and mentorship of a postdoctoral researcher, an undergraduate intern from Palau, and a technician who has now enrolled in a PhD program. Our team shared results with the public through a radio show in Palau, two music concerts in the US, blog posts, and a collaborative art-science program to teach conservation principles to young (K-8) students. Additionally, our scientific results have broad implications for coral reef management restoration efforts, and we have shared our results with the relevant governmental authorities in Palau. 

 

Last Modified: 02/28/2025
Modified by: Kirstin Meyer-Kaiser