Eelgrass
Eelgrass Protection
Eelgrass is the only marine plant in Salem Sound that grows completely submerged underwater. It has long, narrow blades and forms dense meadows that create an important habitat for animals, such as crabs, fish, and birds, to forage and find shelter. We have large eelgrass meadows off the Beverly and Manchester coasts. Protecting eelgrass is critical for Salem Sound’s ecological health, as they provide valuable services to both the ecosystem and human communities that live along the coast.
The Importance of Eelgrass
Due to its importance to both natural and human systems, eelgrass is protected at the federal and state level.
Threats to Eelgrass
Despite eelgrass’ ecological and economical importance, Massachusetts’ eelgrass meadows have declined by about 50% over the past 30 years. Salem Harbor has lost approximately 70% of its historic resources, while the meadows off Beverly and Manchester have remained relatively stable.
- “Wasting disease” specific to seagrass caused a significant die-off of eelgrass in the 1930s, when 90% of meadows were decimated in the North Atlantic.
- Nutrient pollution can create poor water quality (eutrophication), which can impact eelgrass’ ability to photosynthesize, as the murky water blocks sunlight from reaching the sea floor.
- Boating and fishing activities can destroy eelgrass beds by stirring up sediments, leaving propeller scars in shallow waters, and intentionally pulling out eelgrass in shellfishing areas.
- Boat moorings can create circular “scars” in eelgrass beds as the chain scours the sea floor, while floating docks block sunlight, diminishing eelgrass’ ability to photosynthesize and grow.
- Rising ocean temperature due to climate change now poses another major threat. Eelgrass cannot survive in water above 77°F, and wasting disease outbreaks occur more frequently with warming temperatures.
- Green crabs, a common invasive species in Salem Sound, damage eelgrass roots and shoots as they burrow in the sediment for shelter or in search of prey. One study found a 100% decline in eelgrass abundance following the introduction of green crabs to a meadow.
Eelgrass Protection
Salem Sound is fringed with eelgrass meadows, some of which have been stable for decades and are considered relatively pristine, while others, such as in Salem Harbor, are in decline. Protecting this important natural resource is critical for Salem Sound’s ecological health.
For more, check out “The Historic Eelgrass Trends in Salem Sound, Massachusetts Final Report by Massachusetts Division of Marine Fisheries (MA DMF)” in Resources.
