A Scientific Framework for Evaluating Coral Reef Resilience to Climate Change

Hannah Barkley, Ph.D., 2016
Anne Cohen, Advisor

The 21st century warming and acidification of tropical oceans will impact the structure and function of coral reefs. Consequently, conservation efforts are increasingly focused on identifying and protecting communities that demonstrate resilience to these changes. In this thesis, I develop a scientific framework for identifying climate change resilience in coral communities and, using Palau's coral reefs, demonstrate the application of this approach. First, I use coral skeletal records to evaluate the sensitivity of coral reefs to severe thermal stress. This information reveals coral communities that exhibit weak responses to multiple high-temperature events. Second, I evaluate coral community structure across a strong, natural pH gradient, where the coral communities of Palau's Rock Island reefs show a level of pH tolerance that is unique amongst all reefs studied. Third, I conduct experiments to constrain the pH thresholds of these resilient corals and investigate mechanisms for pH tolerance. Finally, I combine archipelago-wide coral temperature and pH sensitivity data to construct resilience indices.  My study succeeds in identifying coral communities that have the potential to withstand climate change and highlights the spatial variability in resilience potential. Critically, I present a set of scientific tools and approaches for identifying resilient coral communities with global applicability.