Project: CAREER: Source-sink dynamics in a restored oyster metapopulation

NSF abstract:

Populations of organisms in different locations are connected by the dispersal of offspring, such as seeds or larvae. Dispersal from populations in favorable environments ('sources') to populations in poor environments ('sinks') can allow the latter to persist where they would otherwise fail to survive. Knowledge about source-sink dynamics is important to conservation and natural resource management. For instance, protecting important source habitats or restoring habitats in locations that enhance connectivity with sinks can improve regional population stability and resilience. Climate variability and change are likely to alter the dynamics of source-sink populations over time, but the effects of these changes are not well resolved, challenging effective decision-making for habitat conservation and restoration. This project will use long-term data, multiyear field experiments, biophysical dispersal simulations, and mathematical population models to address several gaps in the understanding of source-sink dynamics in oysters. By partnering with restoration practitioners, the project will generate knowledge to optimize oyster reef management in the Virginia coastal bays, where the marine environment is rapidly changing. To improve learning opportunities for students underrepresented in science, research methods, data, and specimens will be used to develop a 5th-grade lesson plan on oyster restoration ecology and a 7th-grade field-trip module on oyster biology for public-school students in a rural, high-poverty area of coastal Virginia. Research will also be incorporated into an undergraduate restoration ecology class and a course-based research experience for community college students. Research and teaching tasks will be integrated such that students generate data used to advance the science, students receive hands-on training in marine ecology, and scientific samples and findings are used to develop classroom lesson plans. Data, code, and learning materials will be published publicly online following reproducible and transparent standards.    

Despite intense theoretical interest, temporal variation in the demography and connectivity of source-sink populations has rarely been explored empirically beyond simple lab studies. This project will resolve the patterns, causes, and consequences of temporal dynamics in oyster (Crassostrea virginica) source-sink structure and inform oyster restoration in coastal Virginia. The PI will test the hypothesis that temporal heterogeneity (variation, autocorrelation, and trends over time) in reproductive output, reproductive timing, and oceanographic forcing alters demographic connectivity by developing a biophysical model of oyster larval dispersal parameterized using two decades of environmental and population-monitoring data. Five years of field observations and experiments will be used to empirically determine the drivers of spatial and temporal heterogeneity in the demographic rates that govern source-sink structure (oyster recruitment, survival, growth, fecundity). A Bayesian state-space integral projection model parameterized with dispersal estimates and empirical data will be used to test the hypothesis that temporal heterogeneity in dispersal and demography determine regional oyster population dynamics. The PI will combine models and data with restoration practitioner feedback to develop spatial planning scenarios that improve oyster population size and stability under future climate conditions.