Award: OCE-1851032

 

Coral reefs harbor incredible biodiversity, but are critically threatened by ongoing changes to coastal environments.  Some fishes and invertebrates that reside in close association with corals – collectively known as coral-associated fishes and invertebrates (CAFI) -- can affect how corals grow and survive.  Importantly, the spatial distribution of corals can affect the settlement of CAFI to corals: corals with many neighboring corals receive fewer CAFI due to a dilution effect, while solitary corals have higher densities of CAFI.  As a result, there can be a strong feedback between corals and CAFI.  Our project, based in Moorea, French Polynesia, explored these feedbacks using a combination of literature reviews, field surveys, field experiments, and mathematical modeling and simulation.  Our research informs coral reef management, much of which involves some form of habitat restoration.  However, relatively little is known about how CAFI affect coral health and resilience.  Our work addresses this informational gap and should therefore help inform future management and restoration efforts.  Our project also focused on professional development of training undergraduate students, graduate students, and a post-doctoral scholar, and facilitating public knowledge of coral reef research through several initiatives. 

We reviewed the scientific literature and summarized effects of CAFI on corals, demonstrating the diverse ways in which CAFI can both benefit and harm their coral hosts.  By manipulating the coral landscape and monitoring the CAFI assemblage over 1.5 years, we demonstrated that the spatial distribution of coral colonies alters the development of the CAFI assemblage.  These differences in the CAFI community affected coral physiological traits (e.g., protein content).  Furthermore, by using 3D photogrammetry we demonstrated that CAFI also affected coral growth.  The coral-CAFI feedback caused isolated corals to have more beneficial CAFI and to therefore grow more.

These benefits of CAFI are limited due to the effects of density-dependent mortality of CAFI – which constrains the ultimate density of CAFI that can persist on a coral.  Our modeling efforts demonstrate that CAFI should evolve to selectively settle on larger corals (and avoid small corals), despite the greater resilience that would arise if CAFI settled to smaller corals as well. 

To better understand the factors that influence density-dependence in CAFI, we conducted a meta-analysis of the strength of density-dependence in early life stages of reef fishes, some of which are key members of the CAFI assemblage.  By using advanced methods in meta-analysis that address possible sources of non-independence, we quantified considerable variation in the strength of density-dependent mortality.  That variation is not well explained by traits of the fish or features of the environment.  Although the presence of predators intensifies density-dependence, variation in predator density cannot explain most of the variation in density-dependent mortality.  The factors (still to be fully identified) can lead to considerable variation in CAFI density and thus, their effects on corals.

In addition to these results, our project also focused on the professional development of students (undergraduates and graduates).  Eight PhD and MS students contributed to our project and most of them completed the research for their theses in Moorea.  Our project also engaged the public.  For example, our postdoc collaborated with other educators (e.g., via the QUBES program) to develop a general framework to increase undergraduate quantitative skills and data literacy along with exposure to counter-stereotypical scientists.  Lessons in development pair a data activity (e.g., graph interpretation) with an interview from the scientist who conducted the work.  We also continued our engagement with the “Imagination Squared: Pathways to Resilience” project (https://imaginationsquared.org/), which challenged individuals from the UGA and Athens communities to consider the meaning of resilience (in their work and in their life).  Participants included faculty and students from the Odum School of Ecology, Lamar Dodd School of Art, area middle and high schools, UGA athletes and musicians.  The first phase of the project was permanently installed in the Athens Public Library, and included images of resilience from over 1000 participants.  Additional sounds of resilience, submitted by area musicians and students, are available at the webpage.  A second phase of the project, “Imagination Squared: Resilience in Ecology” continues today (e.g., with undergraduates in classes responding to prompts about resilience). 

Our team also worked with the 'Ātiti'a Center in Moorea to develop educational resources for elementary school teachers in French Polynesia.  American researchers and students were able to share their findings (see https://mooreascience.com/) via video vignettes that introduced researchers and their projects to local teachers and students.  These videos were dubbed in Tahitian by our local collaborators (and provided with English subtitles)

Last Modified: 01/20/2026
Modified by: Craig W Osenberg