Collaborative Research: Understanding the eco-evolutionary mechanisms underlying colonization potential in a tropical seagrass species

About This Grant

Coastal ecosystems are among the most valuable and vulnerable places on earth. These ecosystems support numerous keystone organisms, including habitat-forming species, like seagrass, that serve as the foundation for community structure and function, while also providing critical ecosystem services to people. Unfortunately, seagrasses are increasingly impacted by human activities and have experienced significant degradation and loss over the last century. Further, changes in habitat suitability is causing seagrass species to shift their geographic distributions, resulting in losses of some species and gains of other species in many coastal regions. Along the United States Atlantic Coast, the temperate seagrass, Zostera marina (eelgrass), has declined considerably in recent decades at the southern edge of its range, while the subtropical seagrass, Halodule wrightii (shoal grass), has increased in abundance at the northern edge of its range (North Carolina), where the two seagrass species overlap. This project aims to assess where and how H. wrightii could expand into higher latitudes of the western Atlantic coast, potentially replacing Z. marina as the dominant habitat-forming seagrass. Further, the results of this research will provide critical information and approaches for determining how seagrasses and their associated ecosystem services may shift as habitats become more or less suitable. The outcomes of this project will be used and incorporated into coastal ecosystem management plans, and seagrass monitoring, mapping, and restoration efforts in the United States. Predicting responses of habitat-forming, foundation species is key for ensuring the long-term maintenance of ecosystem structure, functions, and services. Distinguishing eco-evolutionary characteristics of edge-of-range populations that could facilitate or inhibit range expansion can improve predictions for how species may adapt or migrate as habitats become more or less suitable. The overarching objective of this proposal is to determine how shifts in habitat suitability (i.e. temperature, light availability, and biotic interactions) will affect productivity, eco-physiology, gene expression, genetic structure, and colonization potential of a subtropical seagrass at its leading northern range. This project aims to identify ecological, physiological, and genetic mechanisms that may facilitate the expansion of an understudied foundation seagrass species, H. wrightii, into higher latitudes of the western Atlantic coast. The Project Team will examine and evaluate population structure, phenotypic plasticity, and genetic differentiation among H. wrightii populations at range edges versus interiors (stress vs. comfort zones). Manipulative mesocosm and field experiments will be used to evaluate H. wrightii acclimation potential to biotic and abiotic stressors, as well as the effects of a temperate seagrass species, Z. marina, on H. wrightii productivity and gene expression. This project will expand understanding of the abiotic and biotic mechanisms that underlie organismal resilience by examining variation in colonization potential and genetic differentiation of a habitat-forming species at its northern range limit. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.