Coral reef ecosystems are being profoundly affected by climate change. Episodes of mass coral reef “bleaching”, in which corals lose their symbiotic algae (“zooxanthellae”) and turn white or pale, have devastated reefs around the world. These bleaching events are directly linked to periods of unusually high temperatures, such as those occurring in the Caribbean in 2005, the Great Barrier Reef in 2002 and the Indian Ocean in 1998. As a result of these events, coral reefs are now recognized as model systems to study the impacts of climate change, over scales that vary from individual corals to entire ecosystems. Understanding and predicting how coral reefs worldwide will respond to continued climate change in the coming century is a critical area of research in marine conservation, because of its direct links to biodiversity conservation, fisheries management, MPA design and coastline protection.

The principal underlying factor that will determine how coral reef ecosystems respond to climate change is whether the corals that build them will be able to acclimatize or adapt rapidly enough to avoid mortality as thermal stress becomes more frequent and severe. To address this question the Pew Institute’s Reefs of Hope project supports the research of Prof. Andrew Baker at the University of Miami. Dr. Baker’s research investigates the ability of reef corals to contain different types of algal symbionts depending on the environmental conditions they experience. His earlier research has shown that bleaching can actually promote adaptive shifts that favor algae that are more thermally tolerant, and that these shifts are already detectable on reefs that have been severely impacted by mass coral bleaching.

The Reefs of Hope project aims to assess whether corals can mitigate the effects of future climate change by switching or shuffling different algae. Specifically, its goal is to understand how reefs in different parts of the world will respond to climate change. Combining physical oceanographic models of climate change with genetic surveys that monitor the adaptive response of reef corals, this project will help us understand and predict which reefs have the best chance of escaping severe climate change impacts and continue to function as before. This information will help us make useful comparisons of reef response to climate change, inform global marine conservation efforts and help us target reefs most in need of protection over the next 30-50 years.

Principal questions addressed by the Reefs of Hope project:

• Which reefs are most likely to survive over the next 30-50 years?
• How will the species composition of reefs in different regions change over time?
• Will coral reefs of the future resemble those of the past? Will reef communities adapt, acclimatize or go extinct?

Secondary questions that the Reefs of Hope project will help us understand:

What are the consequences of climate change and coral bleaching for marine biodiversity in reef ecosystems?

• Will the diversity and/or density of corals on affected reefs allow these ecosystems to remain functionally intact?