The Great Bay Eelgrass Resilience Project

June 5, 2025 - The Eelgrass Resilience Project was a three-year collaborative research effort designed to bridge science and management and address eelgrass habitat loss in the Great Bay Estuary, NH. The estuary is currently classified as nitrogen impaired, primarily due to significant declines in eelgrass (Zostera marina). Despite more than a decade of discussion, uncertainty remains about the factors affecting eelgrass health and the role of nitrogen reduction—creating challenges for effective action.

This project brought together hydrodynamics, biogeochemistry, and ecology to explore how factors such as water residence time, nitrogen loading, in-situ nitrogen processing, sediment dynamics, and light availability influence eelgrass resilience. The team assessed spatial trends across the estuary and conducted a cutting-edge experiment to measure nitrogen processing along a flow path through an eelgrass meadow. In this webinar, the team presented their scientific methods, key findings, and project deliverables. They also shared insights from working with a Project Advisory Committee that connected the team with municipal and state decision-makers, as well as national experts who provided real-time peer feedback throughout the project.

Speakers: Bill McDowell, University of New Hampshire; Lynn Vaccaro, Great Bay National Estuarine Research Reserve; Kalle Matso, Piscataqua Region Estuaries Partnership

View resources related to the webinar:
https://nerrssciencecollaborative.org...

Learn more about the project and explore associated resources:
https://nerrssciencecollaborative.org...

Join our mailing list for updates:
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00:00 - Intro
01:41 - Management context and collaborative process
09:32 - Overview of research approach and questions
19:02 - Sampling methods and testing multiple hypotheses
23:30 - Hydrodynamic model of Great Bay Estuary
28:38 - Denitrification rate observations explained
31:32 - How different drivers affected eelgrass
33:03 - Summary of findings
34:30 - Lessons learned, benefits, and next steps
42:37 - Q&A