How a Little Mussel could Help Save a Merrimack River Salt Marsh

Annalee Tweitmann stood ankle deep in mud, hands wet with mud, peering at a steep riverbank of mud.

Mud comes with the job, she said, and she’s fine with that. Because mud is where the mussels are.

Tweitmann, a coastal restoration ecologist with Mass Audubon, had come to a salt marsh in Rowley, Massachusetts, to hunt for a creature called the ribbed mussel. Her plan was to transplant some of them from this relatively healthy marsh to an unhealthy marsh a few miles away, which is eroding into the Merrimack River. It’s part of a pilot project to see if mussels could help hold that collapsing marsh together.

Massachusetts has about 45,000 acres of salt marsh — coastal wetlands that are regularly flooded and drained as salt water ebbs and flows with the tides. And these marshes are “incredibly important for so many reasons,” said Tweitmann. They provide habitat for birds, shelter baby lobsters, filter water and protect homes and roads from storm surge. They also store literally tons of carbon in their dense peaty soil — 3-5 more tons per acre than tropical forests, according to the National Oceanic and Atmospheric Administration.

But Massachusetts has lost about 41% of its salt marsh since 1777 — Boston alone has lost 81% — a devastating legacy of human intervention. Colonists used salt marsh grass for roof thatch and animal feed; to increase production, farmers dug ditches and built berms to manage tidal flow. A century later, landowners drained marshes to control mosquitoes or build houses.

The result, said Nancy Pau, a wildlife biologist at the North Shore’s Parker River National Wildlife Refuge: “Some of our marshes are too wet and some of our marshes are too dry, and they have equally negative consequences in opposite directions.”

Read More at wbur.org.