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Evaluating and Enhancing Eelgrass Resiliency and Restoration Potential in a Changing Climate

Evaluating and Enhancing Eelgrass Resiliency and Restoration Potential in a Changing Climate

Long term SAV monitoring transect at the CB-NERRVA Goodwin Island Reserve. Credit: CB-NERRVA/Erin Shields

A network of the intended users from reserves, state agencies, and Chesapeake Bay nonprofits developed a framework to guide eelgrass restoration efforts with an emphasis on climate resilience.

In the lower Chesapeake Bay, Virginia, warmer water temperatures in recent years have resulted in large scale diebacks of eelgrass meadows (Zostera marina). Historically stable, dense eelgrass meadows have converted to low-density, ephemeral meadows. In contrast, many eelgrass populations in Back Sound, North Carolina appear to be more resilient to warming water temperatures. Restoring this iconic species in Virginia and beyond will require understanding the drivers of eelgrass resilience to climate change.

By coordinating a network of the intended users from reserves, state agencies, and Chesapeake Bay nonprofits, this project compared resiliency traits of eelgrass populations in Virginia and North Carolina. The project team worked with a user advisory group, which held regular brainstorming meetings, to design an approach that would inform management decisions related to eelgrass, especially restoration. The team conducted reciprocal restoration trials of Virginia and North Carolina eelgrass seeds (i.e. planting seeds sourced from NC at restoration sites in VA, and vice versa). In addition, the team performed whole genome sequencing of eelgrass sourced from both VA and NC. Restoration trials showed that seeds sourced from NC performed better than local VA seeds at some, but not all, of the restoration sites in VA. Genomic results confirmed that eelgrass populations in VA and NC are locally adapted and use different molecular pathways to achieve resilience to warming conditions.

These results offer insights into the drivers of these regional differences in eelgrass resilience. They indicate the importance of seed sources in potential future eelgrass restoration, in addition to focusing on site selection. The team used the results to develop a draft decision-making framework to guide eelgrass restoration efforts with an emphasis on climate resilience. The framework integrates genomic data, environmental monitoring, and site-specific stressor assessments to inform donor site selection and restoration planning. This framework not only synthesized a wide range of data but also incorporated early and consistent input from the End User Advisory Group, which helped ensure that it was both scientifically rigorous and practically relevant.

The Impact

  • Generated new insights into spatial and temporal patterns of eelgrass resiliency in both North Carolina and Virginia and set the stage for future comparative work with other submerged aquatic vegetation communities.
  • Directly supported the development of two major externally funded initiatives, including a large-scale restoration project funded by the National Park Service and the National Park Foundation, which examines eelgrass populations from North Carolina to Massachusetts.
  • Advanced an innovative framework for eelgrass restoration projects in Chesapeake Bay that incorporates resilience to climate change.
  • Provided professional development opportunities for undergraduate and graduate students to practice bridging research with real-world management needs.