Coral reefs are of great ecological importance, having the highest species diversity of any marine habitat and ranking near the top of all ecosystems with respect to annual total gross productivity. The communities are supported structurally by reef-building corals and trophically by efficient recycling. The key biotic interaction underlying reef systems is the mutualistic relationship between hermatypic corals and photosynthetic zooxanthellae. Hermatypic corals are both functional autotrophs and heterotrophs and derive carbon from multiple sources. In addition to biotic interactions, numerous other biological processes are influenced by a variety of abiotic events that can operate at spatial scales ranging from millimeters to hundreds of kilometers, and which can vary on short to long time scales. Coral reef ecosystems can be affected by perturbations ranging from short and relatively localized disturbances, where return to the original state is possible, to more chronic, widespread influence of shifts in climate over decades that may fundamentally alter the ecosystem. The latter perturbation is predicted to cause sweeping change in coral reef ecosystems in the coming decades. While there are coral reef monitoring programs, descriptive ecology alone cannot elucidate the mechanistic basis of change in these systems. This award will establish a Long-Term Ecological Research (LTER) site focused on dynamics of coral reef ecosystems, at the island of Moorea, French Polynesia, location of the University of California's Gump Research Station. This LTER will estimate long-term trends and address key gaps in understanding through long-term observations and experiments supplemented by shorter-term process studies. The goals are to better understand key processes that (i) modulate ecosystem function, (ii) shape community structure and diversity, and (iii) determine abundance and dynamics of constituent populations. Such mechanistic understanding will allow more accurate predictions of how coral reef ecosystems will respond to qualitatively different types of environmental change. Coordinated interdisciplinary research by the team of 20 investigators will address issues central to the LTER program. The themes that will form the core research thrusts of the proposed LTER include: (1) the biological bases for variation in ecological performance of hermatypic corals (the foundational group); (2) population dynamics of key groups; (3) food web and nutrient dynamics; and (4) the maintenance and functional consequences of diversity. Two additional research components cut across these themes and will help to integrate and generalize the research endeavors of the thematic areas. These are: (a) an explicit focus on physical - biological coupling (including but not limited to abiotic forcing) over multiple scales; and (b) hydrodynamic, food-web and ecosystem modeling to obtain greater insight and predictive power, and to further guide empirical efforts. Major issues within each thematic area will be addressed through focused, process-oriented studies and by long-term monitoring of key abiotic conditions and important ecosystem processes, community attributes, and demographic processes for representative functional groups of organisms. Broader Impacts. Both the scientific community and the public have tremendous interest in and concern about conservation of coral reef ecosystems. This project will greatly increase understanding of these systems, and as such, will inform government officials, resource managers and others charged with conservation and management of coral reefs. LTER cross-site comparisons that reveal generality across different ecosystems will lead to more effective management of natural resources in general. Scientific findings and technical information from the project will be broadly disseminated through a website, scientific publications and presentations, and in the media. Outreach activities will be extensive, and will involve K-12 programs in Southern California as well as community and school outreach in French Polynesia and an internship program for Tahitian university students (coordinated by the Atitia Center). Undergraduate and graduate students from under-represented groups (particularly Hispanic, Native American and Pacific Island) will be involved in an education and research training program, linking California State University Northridge (a minority institution) and University of California Santa Barbara, that will provide training in research, team research experiences, and development of skills needed to carry out interdisciplinary, collaborative research. The project also will engage in post-doctoral training, and will build international linkages between US scientists and those in South Pacific island nations.
The Moorea Coral Reef (MCR) LTER explores community and ecosystem effects of pulsed perturbations and slowly changing environmental drivers on coral reefs, ecologically and economically important ecosystems that are at high risk from local and global stressors. Field operations are based from the University of California’s field station on Moorea, French Polynesia, and the site includes coral habitats in lagoons and the offshore fore reef. Staring in 2007, the fore reef was perturbed by an outbreak of the corallivorous Crown-of-Thorns Seastar (COTS) followed by a cyclone in early 2010. These events killed almost all corals on the fore reef but had little effect in the lagoon. Coral reefs always have been impacted by these kinds of massive disturbances, but never before has there been a reef system with such comparable levels of prior research, high resolution in situ instrumentation and time series measurements made before, during and after such a major set of perturbations. This is providing the MCR with an unparalleled scientific opportunity to address fundamental, unresolved questions regarding disturbance and recovery of coral reefs. The MCR collected several years of time series data before the recent perturbations occurred. Community trajectories from coral reefs in other regions reveal that a rapid return to coral dominance is prevented if macroalgae become widely established following the sudden death of coral, a state shift that is becoming more common in the Caribbean and Pacific. Our research focused on the processes that prevent a shift to macroalgal dominance following loss of coral. Herbivory has long been known to be a critical process on coral reefs that can prevent a state shift to macroalgae, and management strategies to enhance resilience of coral reefs emphasize actions to avoid overfishing herbivores. Despite this, it is not well understood how herbivores respond to the sudden, widespread loss of coral. MCR’s time series data and field experiments provided novel insights into behavioral and dynamical responses of coral reef herbivores that have fundamental implications for management strategies to enhance resilience. Following the recent perturbations to the fore reef, the abundance and biomass of herbivorous fishes increased rapidly, and grazing by these fishes prevented a state shift to macroalgae. Importantly, most of these herbivores were parrotfishes, which initially recruit to nursery habitat within the lagoon before moving to the fore reef later in life. Our work reveals critical connectivity between inshore and offshore reefs, and indicates that protecting nursery habitat of key herbivores is essential for maintaining reef resilience. While coral cover has fluctuated tremendously on the fore reef, it has varied far less in lagoons. However, previous perturbations triggered an important shift in the species composition of corals in lagoon habitats. The abundance of acroporid corals fell, especially the thicket-forming staghorn coral, a major provider of habitat for fishes and invertebrates. Staghorn Acropora has recovered little over the past 30 years. Consequently we asked what governs the population dynamics of key species of corals. We found that acroporid corals are more susceptible than other types of corals to predators. The reason for the slow recovery of staghorn Acropora is that they must be defended from corallivores by a territorial farmerfish. We also found a second, potentially ubiquitous means by which coral-dwelling fishes can greatly affect their coral habitat. Numerous species of fishes use coral structure for shelter; we found that the abundance of fishes is positively related to the size of their coral host, and that the growth rate of the coral is enhanced by its associated fishes due to excretion of nitrogenous waste. Since most of the fish are planktivores, this represents an important flow of nutrients from the water column to the benthos. While we have long known that the amount of coral on a reef influences the number and type of fishes present, our findings show that the reverse often is true - the type of fishes present can markedly enhance the amount of coral on a reef. Thus our studies of fish – coral interactions are revealing critical roles that fishes play in the resilience and dynamics of corals. A total of 18 postdoctoral investigators, 64 graduate students, 63 undergraduates, 53 technicians / programmers and 6 K-12 teachers participated in this project. Web sites associated with this project: 1) http://mcr.lternet.edu/ Description: This is the main web site for the Moorea Coral Reef LTER site. It provides access to MCR LTER data, personnel, education pages and public information. 2) http://mcr.lternet.edu/education Description: This is the main web site for the Moorea Coral Reef LTER site Educational and Outreach materials. It includes an encyclopedia of marine life of Moorea and teacher resources such as K-12 lesson plans and curricula. 3) http://mcr.lternet.edu/data/realtime/ Description: This displays meteorological and oceanographic data in real time from the Gump Research Station in Moorea.
