The role of diel thermal variability on coral performance

Rising ocean temperatures threaten coral reefs worldwide by causing coral bleaching—a phenomenon where corals expel their symbiotic algae due to stress. However, recent field studies and experimental evidence suggest that corals from environments with higher diel thermal variability (DTV) exhibit greater thermal tolerance and increased potential for physiological flexibility. This project addresses the urgent need to understand the mechanisms by which DTV can potentially mitigate coral bleaching by enhancing resilience and thermal tolerance. By integrating field and experimental data in a resilient reef-building coral species, this research establishes how DTV influences traits critical to coral survival, including coral growth, thermal performance, and physiological flexibility across varying thermal environments in Bocas del Toro, Panamá. Such insights are crucial for predicting coral bleaching under future climate scenarios and inform strategies for reef conservation and restoration efforts worldwide. This project includes the mentorship of a postdoc, two graduate students, three Panamanian interns, undergraduate students, and high school students from local Boston, MA schools. Outreach initiatives enhance public understanding of coral reef ecosystems through an interdisciplinary bilingual hybrid concert combining music and science in live performance, which are live-streamed to English and Spanish speaking audiences in the US and Panamá. This project is determining the mechanisms underlying how diel thermal variability (DTV) influences coral thermal physiology and performance. The central hypothesis of this research posits that DTV enhances coral resilience by promoting physiological plasticity, thereby improving responses to thermal challenges that can cause coral bleaching and mortality. To address this hypothesis, this project quantifies how differences in DTV influence the plasticity of coral thermal physiology and molecular function, focusing on a tractable study species (Siderastrea siderea) across six reef sites in Bocas del Toro, Panamá. The project's specific goals include: (1) establishing long-term baselines of environmental variability across sites and seasons, (2) determining if differences in DTV lead to increased plasticity in thermal physiology, and (3) testing how DTV around different mean temperatures within the context of a coral's thermal performance curve (TPC) impacts growth and physiology. By addressing these objectives, the research advances fundamental knowledge of coral thermal biology, with implications for predicting coral reef persistence and guiding effective conservation strategies amidst accelerating climate change. This project is jointly funded by Biological Oceanography and Integrative Ecological Physiology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.