Community Ecology of Coral Reefs of Moorea

Project 1. Impact of corallivory on long-term coral health - One of our main projects is to understand how predation on corals by different types of fishes such as parrotfishes, pufferfishes, and butterflyfishes impacts long-term coral health and survivorship. Predation on corals is an important process on coral reefs. However, there has been little that has been done to characterize the community wide patterns of corallivory by parrotfishes, pufferfishes, and butterflyfishes in terms of how they select for different coral species in their diets. We will document community-wide patterns in predation scars from these large corallivores to document how different species of fishes chose different corals to consume. We will then track the long-term fate of corals that get preyed on to understand how predation impacts coral survivorship across the different types of reefs in Moorea. Understanding these corallivory dynamics will be important to understanding the long-term health of Moorea coral reefs as both coral and fish communities change with global change.

Project 2. Role of fish-derived nutrients in coral reef ecosystems - Animals are significant links in biogeochemical cycles, recycling nutrients back to the environment via excretion and making limiting nutrients available to primary producers. Our work on other coral reefs shows that the input of nitrogen from fishes is over 25X greater than all other sources of nitrogen on these reefs combined (e.g. anthropogenic nitrogen, nitrogen fixation, atmospheric nitrogen deposition). Consequently, these fishderived nutrients can facilitate cover of macroalgae and suppress density of juvenile corals via competition with macroalgae. Specifically, our work in Moorea on fish-derived nutrients will address how this fish-mediated nutrient cycling on reefs impacts: (1) the spatial distribution of nutrients within reefs, (2) algal primary production across seasons, (3) coral growth, fecundity, and recruitment, and (4) the nutrient limitation and growth of herbivorous fishes.

Project 3. Impact of herbivorous fishes and nutrients on coral reef communities - Much of our research will examine the importance of herbivory and herbivore species richness in affecting ecosystem function of Moorea coral reefs. We will examine how increasing species richness of herbivores allows for complementary feeding on different species of algae, more efficient removal of algal biomass, and increased growth and survivorship of corals. Our upcoming work will address broader complementarity across the whole herbivore guild on reefs in Moorea. Currently, my lab is designing research on theecology of herbivorous fishes by addressing the mechanisms that drive interspecific differences in feeding patterns. Ultimately, this work will allow us to identify specific herbivores that are overwhelmingly important for the removal of macroalgae and the mechanisms of nutritional ecology that drive these patterns.

Project 4. Impact of nutrient pollution on coral bleaching  We will also examine the impacts of nutrient pollution on coral bleaching on the reefs of Moorea. Our research on nutrient pollution and coral bleaching in Moorea is focusing on two major aspects: (1) island-wide patterns in bleaching and coral loss with respect to landscape-scale nutrient availability and (2) how different forms and sources of nutrients can either facilitate or mitigate bleaching. In particular, we are testing the hypotheses: (1) that coral bleaching in response to elevated ocean temperatures will be greatest at sites experiencing the
highest levels of anthropogenic nutrient enrichment and (2) that nitrate enrichment from anthropogenic sources will increase the susceptibility of corals to bleaching to a greater degree than recycled nitrogen in the form of ammonium (i.e. more fish-derived sources).