Project: Thermal stress and differential recovery of coral reefs

NSF Award Abstract:

Coral reefs are the world’s most diverse marine ecosystem that provide invaluable goods and services for millions of people worldwide. Yet, coral reefs are experiencing thermal-stress events worldwide and their communities are changing. While coarse-grained climate models predict that few coral reefs will survive the 3ºC sea-surface temperature rise in the coming century, field studies show localized pockets of coral survival and recovery, even under high temperature conditions. Quantifying recovery from thermal-stress events is central to making accurate predictions of coral reef trajectories into the near future. This study examines the differential rates of coral recovery following thermal-stress events, globally, and determines the extent to which regional and local conditions influence recovery. This research is taking advantage of the recent progress in spatio-temporal analyses. One of the most transformative aspects of this work is determining where coral recovery rates differ from expectations, and how those differences relate to regional and local conditions. The research is of relevance to all persons that live and work near coral reefs. What happens to reef corals has cascading consequences on other reef-associated organisms and influences whether coral reefs can keep up with sea-level rise. This project is increasing scientific capacity by training a post-doctoral scholar and a PhD student in big-data analysis and making these analysis techniques broadly available. High quality and free online tutorials are supporting standards-driven instruction for high school math, science, and computer teachers in R, a programming language and software environment used for statistical computing and graphics. The project is producing large-scale data and computational resources, which are benefitting diverse users such as students, scientists, resource managers and the broader public.

The current rapid rate of climate change threatens coral reefs. Quantifying recovery from thermal-stress events is central to making accurate predictions of coral-reef trajectories into the near future. Coral populations in different geographic regions and under different local conditions vary in their capacity to tolerate or recover from thermal stress. However, how and why coral responses differ remains poorly understood. There is a clear need for accurate predictions of coral trajectories following thermal-stress events and for determining which interacting factors most influence coral recovery. This study is characterizing the relationships between the rates of coral recovery, frequency and intensity of thermal-stress events, geographic location, habitat, and local conditions that slow or enhance coral recovery. Four approaches are being used to analyze coral recovery: (i) a binary approach, (ii) a meta-analysis approach, (iii) an inverse-problem approach, and (iv) a state-space approach. Spatial and temporal differences in rates of coral recovery are being quantified by capitalizing on the latest developments in spatio-temporal analyses within a Bayesian framework. Observed outcomes of coral recovery are being compared with predicted outcomes to identify areas where recoveries are either higher or lower than expected, and to assess context-dependencies of coral recovery in relation to local and regional conditions. The most transformative aspect of the study is the identification of localities with greater than expected recovery rates, which could guide future conservation decisions by enabling managers to target coral reefs with specific characteristics for protection from human disturbances by designating them as potential refuges as the oceans continue to warm.

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.