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Key Water Reporter Issues
Eelgrass
Eelgrass is a flowering underwater marine plant that provides critical habitat, stores carbon, and helps keep our water clean. Water Reporters can help by sharing photos of healthy eelgrass beds, patchy areas, or large amounts of eelgrass washed ashore. Extreme low tides are an ideal time to spot and document eelgrass around the Bay.
Why Track Eelgrass?
Eelgrass is a critical coastal habitat that supports fish, lobster, and shellfish, protects shorelines from erosion, and helps buffer climate change by capturing carbon and reducing ocean acidification.
But eelgrass is in danger. It is disappearing fast. From 2018 to 2022, Casco Bay lost 54% of its eelgrass, and the decline continues.
Friends of Casco Bay is part of a collaborative pilot project to study and restore eelgrass. Water Reporters are helping us document where eelgrass is thriving, thinning, or washing ashore—giving us valuable clues about what’s driving this decline.
What to Look For
Eelgrass (Zostera marina) is often confused with green algae or salt marsh grass—but there are some key differences:
Eelgrass is almost always underwater, except during extreme low tides. It’s a true submerged aquatic plant with long, ribbon-like leaves that sway in the current.
Unlike algae, eelgrass has roots and a clear structure. It grows in beds anchored to the seafloor from the low tide line to about 10 feet deep.
Compared to salt marsh grass, which stands upright and out of the water, eelgrass lays flat when exposed and needs to stay submerged to survive.
In wintertime, you might spot geese swimming over eelgrass beds and snacking on the blades.
Shredded roots are tell-tale signs of green crab damage to eelgrass beds.
Tap or click any image to open the full gallery.
Eelgrass vs. Salt Marsh
How to Identify Eelgrass Versus Salt Marsh Grass
- Eelgrass grows underwater and is usually submerged. During extra low tides, you can see eelgrass lying flat like limp noodles.
- Salt marsh grass stands upright and is mostly dry, growing from mud or soil at the water’s edge. It is exposed during most tides, but is sometimes submerged during high tides.
Eelgrass grows in shallow underwater areas of bays and inlets; salt marshes resemble grassy fields and can stretch inland.
Think of salt marsh grass like uncooked spaghetti—stiff and upright. Eelgrass, on the other hand, is more like cooked linguine—soft, flat, and flowing.
How & When to Document Eelgrass
Eelgrass is typically hidden under the water, except during a few periods of extreme low tides throughout the year—the perigean and king tides—when eelgrass beds are exposed.
We send out notices to Water Reporters when there is going to be an extremely low tide.
We also hold Seagrass Snapshots, calling on Water Reporters to get out and document eelgrass during key low-tide dates.
How You Can Help Eelgrass
- Stop or minimize the use of fertilizers on your lawn or garden.
- Tread carefully in eelgrass areas while boating, working, swimming, or wading in the water.
- Help us track eelgrass as a Water Reporter!
- Advocate for clean water.
Learn More About Eelgrass
2025 Seagrass Snapshot
Water Reporters explored mudflats and shallow waters during extremely low tides to document where eelgrass thrives, and where it is missing in Casco Bay for the 2025 Seagrass Snapshot.
The Superheroes of Casco Bay: Eelgrass Meadows: A Vital Ecosystem in Peril
These superheroes of the ocean have been quietly keeping our oceans healthy, our fisheries abundant, and our coastlines intact – yet eelgrass meadows are disappearing at an alarming rate.
A Friend to Eelgrass: A Water Reporter Helps Look After a Vital Ecosystem in Peril
Casco Bay’s eelgrass is in peril. Susan Woodman began photographing the eelgrass meadows at Willard Beach about a year ago as a volunteer Water Reporter for Friends of Casco Bay.
Coffee with the Casco Baykeeper: Eelgrass
Casco Baykeeper Ivy Frignoca shares her concern about eelgrass disappearing from Casco Bay and what Friends of Casco Bay is doing about it.