Jump to...
The Great Salt Bay Eelgrass Restoration Project
Bordering the towns of Nobleboro, Newcastle, and Damariscotta, Great Salt Bay is a unique upper estuary salt bay. It supports horseshoe crabs, ospreys, quahogs, and sturgeon. Over 1 million alewives and American eels migrate through every year. The foundation of this ecosystem is eelgrass!
Unfortunately, Great Salt Bay has lost over 300 acres of eelgrass since the 1990s. This loss is staggering and has far reaching implications for water quality and fish habitat throughout the entire Damariscotta River estuary.
What is eelgrass?
Eelgrass (Zostera marina) is a flowering marine grass that forms dense meadows underwater. It is the foundation of entire food webs and serves as essential fish habitat in Great Salt Bay. It likes clear, clean water so its blades can photosynthesize.
What is causing eelgrass to disappear?
The reason eelgrass is dying in Great Salt Bay is likely a combination of many different factors, including rising temperatures, excess nutrients in the bay, and an overabundance of invasive European green crabs. Of these, nutrient levels and green crab populations are the areas where our actions will have the biggest impact.
Keeping nutrients in check
In August 2025, high levels of nitrogen were sampled throughout the Bay and a large algae bloom was found off Massachusetts Island. Another bloom was found in June 2026, pictured here.
Turf algae, as it is known, is actually many species or communities of algae and cyanobacteria that grow on other plants, including eelgrass. It forms short, dense, carpet-like mats that reduce light and smother marine plants. Turf algae thrives in high-nutrient, high-light, and low-flow environments. Reducing nutrients (nitrates and phosphates) which can come from septic systems, pet waste, and fertilizers, can help keep its growth in check.
> Water quality monitoring is a key component of the Eelgrass Restoration Project, and regular updates will be shared in our newsletter (sign up below)!
Managing invasive green crabs
Native to the Atlantic coasts of Europe and Northern Africa, the European green crab arrived along the eastern coast of North America in the early 1800s, primarily transported via ballast water in shipping vessels. Highly adaptable, they tolerate wide ranges of salinity and water temperature, allowing them to rapidly colonize coastal estuaries.
Green crabs are prolific and are voracious eaters. As they burrow into the mud and dig for prey (such as clams and worms), they shear through the root structures of eelgrass, uprooting whole patches and destroying the bed’s integrity.
> The trapping and removal of green crabs will be critical to eelgrass restoration in Great Salt Bay. We hope to find a commercial market for the crabs, such as in the production of fertilizer.
What can I do to help?
Help reduce nutrient runoff in Great Salt Bay
- Avoid fertilizing as much as possible. If you must fertilize, avoid doing it before a heavy rain.
- Plant native buffers with deep roots around sources of nutrients like gardens, lawns (geese poop!), animal pens, and agricultural fields.
- Keep septic systems well-maintained and be sure to have them pumped out on a schedule appropriate for their use and size.
- If you are a property owner on Great Salt Bay, consider participating in the Conservation Landscape Certification Program with Knox-Lincoln Soil and Water Conservation District or a shoreline resilience site visit with Coastal Rivers Conservation Trust. These free services help landowners implement conservation practices with one-on-one support and on-site technical assistance. Contact the GSB Eelgrass Restoration Project for more information!
Volunteer!
Eelgrass restoration takes people power. Over the seven years of the GSB Eelgrass Restoration Project we will be looking for…
Snorkelers to harvest and plant eelgrass and monitor the bay
Divers to monitor eelgrass meadow conditions in deeper areas of the bay
Community scientists to process eelgrass seeds and configure restoration equipment
Fishers and harvesters to join the volunteer green crab trapping program
If you are interested in volunteering, please fill out this Google form to be added to the volunteer list.
Sign up for the Great Salt Bay eelgrass newsletter
Hear about project updates, get news from the Bay, and volunteer to support restoration fieldwork and community science!
Contact the Great Salt Bay Eelgrass Restoration Project
Devin Domeyer, Maine Coastal Program: devin.domeyer@maine.gov
Sarah Gladu, Coastal River Conservation Trust: sgladu@coastalrivers.org
