Ocean Acidification and Coral Reefs - Scale Dependence and Adaptive Capacity

Ocean Acidification (OA) is perhaps the most serious threat to marine ecosystems. This project and addresses the problem in the most diverse and beautiful ecosystem on the planet, coral reefs. The research utilizes Moorea, French Polynesia as a model system, and builds from the NSF investment in the Moorea Coral Reef Long Term Ecological Research Site (LTER) to exploit physical and biological monitoring of coral reefs as a context for a program of studies focused on the ways in which OA will affect corals, calcified algae, and coral reef ecosystems.

The project builds on a previous NSF-funded OA project at the Gump Station, adding research in five new directions:

1. experiments of year-long duration, 
2. studies of coral reefs to 20-m depth,
3. experiments in which carbon dioxide will be administered to plots of coral reef underwater, 
4. measurements of the capacity of coral reef organisms to change through evolutionary and induced responses to improve their resistance to OA, and
5. application of emerging theories to couple studies of individual organisms to studies of whole coral reefs.

Broader impacts will accrue through a better understanding of the ways in which OA will affect coral reefs that are the poster child for demonstrating climate change effects in the marine environment, and which provide income, food, and coastal protection to millions of people living in coastal areas, including in the United States.

Additionally, the research will have broad-reaching and cascading effects at multiple levels associated with public awareness of climate change effects, and the preparation of an American workforce focused on Science, Technology, Engineering and Mathematics (STEM) careers. These effects will be realized by basing the research in a 4-year, Hispanic-serving campus California State University Northridge (CSUN) where undergraduates will have strong involvement in the project through classroom instruction and Research Experience for Undergraduates (REU) opportunities, and postdoctoral, graduate, and technical staff opportunities will be supported. An ongoing program of high school involvement will be extended to include K-12 educators in Moorea, and integration of lesson plans between local schools and CSUN.

This project focuses on the effects of Ocean Acidification on tropical coral reefs and builds on a program of research results from an existing 4-year award, and closely interfaces with the technical, hardware, and information infrastructure provided through the Moorea Coral Reef (MCR) LTER. The MCR-LTER, provides an unparalleled opportunity to partner with a study of OA effects on a coral reef with a location that arguably is better instrumented and studied in more ecological detail than any other coral reef in the world. Therefore, the results can be both contextualized by a high degree of ecological and physical relevance, and readily integrated into emerging theory seeking to predict the structure and function of coral reefs in warmer and more acidic future oceans.

The existing award has involved a program of study in Moorea that has focused mostly on short-term organismic and ecological responses of corals and calcified algae, experiments conducted in mesocosms and flumes, and measurements of reef-scale calcification. This new award involves three new technical advances: for the first time, experiments will be conducted of year-long duration in replicate outdoor flumes; CO2 treatments will be administered to fully intact reef ecosystems in situ using replicated underwater flumes; and replicated common garden cultivation techniques will be used to explore within-species genetic variation in the response to OA conditions.

Together, these tools will be used to support research on corals and calcified algae in three thematic areas:

1. tests for long-term (1 year) effects of OA on growth, performance, and fitness,
2. tests for depth-dependent effects of OA on reef communities at 20-m depth where light regimes are attenuated compared to shallow water, and
3. tests for beneficial responses to OA through intrinsic, within-species genetic variability and phenotypic plasticity.

Some of the key experiments in these thematic areas will be designed to exploit integral projection models (IPMs) to couple organism with community responses, and to support the use of the metabolic theory of ecology (MTE) to address scale-dependence of OA effects on coral reef organisms and the function of the communities they build.