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Lessons in adaptation help address sea-level rise at Musquash Marsh

How restoring a salt marsh helps to protect one of
New Brunswick’s most important coastal ecosystems

November 15, 2019
© DUC

The Bay of Fundy is home to some of the highest tides in the world. Twice a day, every day, the ocean rises upwards of 16 metres, and then drops back down six hours later. When the tide is out, you can walk the ocean floor. Up and down the bay’s coast, this constant motion has created unique and varied wildlife habitat. And the Musquash Estuary is no exception.

Estuary 101

Estuaries are where saltwater from ocean tides meet fresh water flowing from rivers and streams.

Located west of Saint John, near the mouth of the Bay of Fundy, Musquash Estuary stretches several kilometres inland from the coast and is one of the largest habitats of its kind in New Brunswick. Designated as a federal marine protected area in 2006, it’s home to orchids, harbour seals, and black ducks. It encompasses forests, open water, and a salt marsh.

Just above the northern tip of Musquash’s protected area are three freshwater wetlands. We restored these wetlands in the 1980s. This unused agricultural land had historically been a salt marsh before it was diked off from the rest of the estuary in the 17th century. In the 1970s and 80s, it was a general practice to convert former saltmarshes—which had typically been drained or cut off from the ocean by these agricultural dikes—to freshwater wetlands.

Adapting wetland conservation strategies to address sea-level rise

A few years ago, our Atlantic conservation team started to notice big changes to the landscape. Stronger storms and waves from higher sea levels were eroding the dike separating the restored freshwater marsh from the estuary’s salt water.

Without intervention, ocean water would wash away entire portions of the dike. And once those famously strong Bay of Fundy tides started flowing into the freshwater marsh, they’d also erode the shoreline behind it.

For Adam Campbell, DUC’s head of conservation in Atlantic Canada, the solution was clear. “It didn’t make sense to fight sea-level rise by building the dike higher,” says Campbell. “Coastal salt-marsh restoration was the way forward.”

Common Gallinule
Common Gallinule © DUC

The plan was to let the water flow where it wanted to, but help it move more gradually. In 2018, we opened holes in the dike to allow salt water and sediment to wash in. Tide by tide, this wetland began its conversion from freshwater back to salt marsh. Soon, mud flat areas full of dense salt grass, will emerge

to better buffer against sea-level rise and the punishing waves from storm surges. Best of all, Musquash Marsh will add to the ecological value of the surrounding marine protected area.

 
  © DUC

New research and climate change inform best practices on the Atlantic coast

DUC looks after thousands of hectares of wetlands like Musquash near or along Atlantic Canada’s coast. Over time, we’ve learned a lot about the ecological needs of areas we’re conserving. New research and on-the-ground conservation work informs new best practices. Today, as these areas face new environmental challenges —challenges that impact all of us—salt marsh restoration is an essential part of our coastal conservation strategies.