racoon tracks

This is the first update about the Great Bay Eelgrass Resilience Project. Periodic updates like this one will help keep communities around Great Bay and others informed and engaged and provide a preview of results as they begin to emerge. 

After nearly a year of planning, consultations and proposal writing, GBNERR staff are helping launch the  Great Bay Eelgrass Resilience Project. Here are the basic specs for the project.

    • Full project title: Resilience and positive feedbacks: Water quality management and eelgrass health in the Great Bay Estuary, NH/ME
    • Project timeframe: Fall 2021 – Fall 2024
    • Project partners: University of New Hampshire and Piscataqua Region Estuaries Partnership
    • Funder: NERRS Science Collaborative
    • Primary objectives:
      • Improve understanding of what drives eelgrass health and resilience
      • Fill science gaps to help adaptively manage eelgrass and nitrogen in Great Bay

      Why research eelgrass in Great Bay?

      Seagrasses are a vital component of healthy estuaries here in New England and throughout the world. They are rooted, flowering plants that grow underwater and are typically submerged, even at low tide. Nearly all the seagrass beds found in Great Bay are composed of a single species commonly known as eelgrass, Zostera marina.

      When healthy, eelgrass forms dense underwater meadows that provide essential habitat and oxygen for fish and shellfish. The roots of eelgrass plants hold sediment in place, while the long leaves slow waves and tidal currents, causing suspended sediments to settle out and helping prevent coastal erosion. 

      Unfortunately, eelgrass has been declining in Great Bay over the past 20 years, which is one of the factors that led EPA to develop the Great Bay Total Nitrogen General Permit in 2020. This 2 minute video describes eelgrass trends locally, and this 1 minute video visually compares healthy and less healthy eelgrass meadows in Great Bay.

      Great Bay is not the only place struggling with these issues – eelgrass populations are declining in many parts of the US. While eelgrass can handle a wide range of temperatures, water depths and salinity levels, the plants, especially seedlings, need high light levels. In many coastal areas, excess sediments and nutrients alter water quality, limiting the amount of sunlight that can penetrate the water, which in turn slows or prevents the growth of eelgrass. Other factors, such as intense storms and diseases, can also damage eelgrass meadows.  

      The Great Bay Eelgrass Resilience project will closely examine the connections between eelgrass health, water quality and water flow patterns in Great Bay. The team will look at these relationships from two angles. First, by looking for spatial patterns and correlations between eelgrass health and different physical and chemical variables, we will try to tease out what factors seem to be impacting growth locally. Second, we will use state of the art approaches to measure how eelgrass can affect the water it lives in, potentially improving water quality and increasing its own resiliency. For example, to what extent does eelgrass stimulate denitrification in the sediment, promote the removal of nitrogen from the water, and improve water clarity?

      Thanks to significant upgrades to wastewater treatment plants around Great Bay, nitrogen inputs to the Bay have been declining. With water quality improving, eelgrass may be better able to recover and expand its coverage, leading to further improvements in the Bay. Although we’re not sure what this project will reveal, we are eager to collaborate closely with local and state decision makers to make sure we are learning from and contributing to the ongoing management of Great Bay. For example, we hope this research will spark new ideas for restoring eelgrass meadows, help us prioritize future investments, and adaptively manage the Bay’s water quality.

      The Eelgrass Resilience team has assembled a Project Advisory Committee that will provide input throughout the project to ensure results are relevant, trusted and useful. The group includes representatives from the towns around Great Bay as well as the agencies and organizations involved in protecting water quality and habitats.The current advisory committee membership is here


      Want to learn more?

      deer scat
      2 deer beds with tracks nearby