Overview:

Many nearshore marine ecosystems are defined by habitat-forming species (e.g., kelp, oysters, and coral) that provide shelter and food to other organisms. As a result, spatial variation in the amount, size and distribution of habitat-forming species plays a central role in determining patterns of density and diversity of associated fauna. While it is well-known that many occupants of biogenic habitat also affect the dynamics of the habitat itself (e.g., through consumption or fertilization), the role of bidirectional habitatoccupant interactions in driving the dynamics and spatial patterns of occupants and their habitat is poorly understood. The proposed research addresses these feedbacks in coral reef ecosystems. Specifically, we will study bidirectional interactions between corals in the genus Pocillopora (an important biogenic habitat) and the coral-associated fishes and invertebrates (CAFI) that depend on these corals for their persistence. The project uses field surveys, mesocosm and field experiments, and mathematical models to investigate the feedbacks in the coral-CAFI system by: (1) quantifying variation in the coral-CAFI spatial landscape; (2) testing the effects of habitat attributes (coral density, size, and proximity) on the settlement of CAFI and on the distribution of signals used by larvae to locate habitat; (3) testing the effects of habitat attributes on CAFI density (incorporating effects on settlement and post-settlement processes), on coral condition, growth, survival, and on the services that CAFI provide to the coral; and (4) extrapolating these shorter-term effects to understand long-term (e.g., multi-decadal) dynamics. This will be accomplished by building, parameterizing, evaluating, and applying a model that translates short-term experimental results into predictions of coral-CAFI dynamics on larger temporal and spatial scales. The model will be used to evaluate how coral ecosystems recover from disturbances, in light of the coral- CAFI feedbacks.

Intellectual Merit:

The mechanisms that underlie the effects of habitat configuration on the density of its occupants remain poorly understood. The proposed research tackles this problem by proposing and testing a mechanism (which we term ?propagule redirection?) that has the potential to explain diverse empirical relationships between habitat amount, patch size, and proximity on occupant density. Furthermore, the feedbacks that arise from the effects of occupants on their habitat are largely absent from past studies of landscape dynamics. Because variation in habitat attributes drives variation in occupant densities, which in turn likely drives the dynamics and distribution of the habitat itself, such feedbacks are a critical, albeit currently missing, component of landscape ecology. Further study of this connection will offer novel understanding regarding the creation of spatial patterns in habitat and associated fauna, and illuminate consequences of habitat loss and fragmentation that many systems defined by habitat-forming species are currently experiencing.

Broader Impacts:

This project will: (1) facilitate restoration effects; (2) enhance the scientific workforce; and (3) engage the public in scientific research and knowledge. For example, results of this project will provide insights about the restoration, conservation, and ecosystem-based management of coral reefs, a threatened and economically important ecosystem. Through a continuing collaboration with the NOAA Ecosystem Science Program, scientific outputs will be connected with opportunities to improve marine conservation and policy. Further, by coordinating with the Moorea Coral Reef LTER program, the project will benefit (and benefit from) ongoing studies of that ecosystem. This award facilitates NSF?s Strategic Framework for Investment in Graduate Education by training several early career researchers including one postdoc, two PhD students, and several undergraduates. Students will be fully engaged in the research and will present products of this project at several venues, including national conferences. To include personnel from diverse backgrounds, PIs will coordinate with recruitment programs at UCSB, UGA, and Tulane (e.g., UCSB's Bridge to Doctorate Program). Outreach to the public will be conducted in French Polynesia (e.g., via the Atitia Center) and at the PI's home institutions, and will include a range of activities, including science fairs, ocean awareness programs, and community engagement projects designed to link arts and science.