Postdoctoral Fellowship: OCE-PRF: How does the increasing prevalence of weedy species alter community interactions and coastal ecosystem functioning?

The number of species is declining globally, and weedy species that grow and reproduce quickly are becoming increasingly dominant in many marine ecosystems. It is important to understand how the increased prevalence of weedy species will affect other organisms and the environment to better manage and conserve these changing ecosystems. This project will use large-scale field experiments to learn more about how different species of seagrass (both weedy and non-weedy) interact with different types of bivalves and how their interactions affect multiple aspects of coastal carbon cycling.

Field experiments that include realistic fluctuations of the natural environment will improve understanding of seagrass-bivalve interactions in natural settings and their potential impact on the carbon cycle. Results from this project will enhance conservation and restoration strategies of both seagrasses and bivalves and may be upscaled to inform global carbon budgets.

As a part of this project, research and mentoring opportunities will be extended to undergraduate students, including individuals from underrepresented groups, to broaden participation in the field of ecology. This project will also advance literacy in environmental sciences through the development of a K-12 lesson plan on seagrass-bivalve interactions to teach students about the role of species interactions in ecosystem health.

Observed and anticipated community composition shifts toward assemblages dominated by early successional species will affect species interactions, and in turn, alter biogeochemical cycling and resiliency to global change. Seagrass meadows are an ideal system for studying community effects on ecosystem function because multiple seagrass species with varied life history strategies often co-exist, and as foundation species, they support and interact with several other species.

Seagrasses are also lauded for their potential to store large amounts of organic carbon in underlying sediments, but their role in driving inorganic cycling, including dissolved inorganic carbon and total alkalinity production, is not as well studied but can affect the net carbon storage capacity of seagrass meadows. Seagrass-mediated changes in dissolved inorganic carbon and total alkalinity can also impact pH-sensitive organisms living within seagrass meadows, including bivalves, and bivalves in turn interact with sediments and the water column in ways that affect both organic carbon storage and the balance of dissolved inorganic carbon and total alkalinity in the carbonate system.

The proposed research will investigate how seagrass species and bivalve functional traits interact to influence organic and inorganic carbon cycling using large-scale field experiments. Specifically, this study will first assess how the strength and direction of species interactions change across seagrass species identity and bivalve functional form by evaluating seagrass and bivalve growth metrics in bivalve-addition manipulations in meadows dominated by early successional (r-selected) vs. climax (k-selected) seagrass species.

Using the same experimental approach, this study will also address the impacts of seagrass-bivalve interactions on surface sediment organic carbon storage, decomposition rates, and seawater carbonate chemistry. The findings from this study will deepen understanding of the potential for seagrass facilitation of pH-sensitive organisms in natural settings and the role of faunal communities in driving seagrass meadow carbon sink capacity.

This study will therefore have implications for the management and conservation of coastal ecosystems as climate change and other anthropogenic stressors increase the extent and severity of coastal acidification and continue to alter foundation species assemblages.

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.