Atlantic, Wetlands

A saltwater solution for sea-level rise at Fullerton’s Marsh

Saving Prince Edward Island from the threat of sea-level rise

November 23, 2020

In Canada’s smallest province, DUC restores a salt marsh to slow erosion caused by rising seas

From space, Prince Edward Island looks like a skiff of sand on the edge of the Atlantic Ocean.

Here, the ocean is a constant, something Islanders have built their lives around, from the fishing industry to tourism. But the ocean is also an unstoppable force, something Islanders have also learned to guard against—and prepare for—as sea levels continue to rise, changing the shape of their picturesque province.

Rising tides, sinking land, and stronger waves threaten coastlines

Rising global temperatures are melting glaciers and sea ice, pouring an excess of water into Earth’s oceans. Add to this the fact that our region’s landmass has been slowly sinking since the last ice age. According to research by Adam Fenech at the University of Prince Edward Island’s Climate Lab, an average of 28 centimetres of coastline is eroding on P.E.I. each year. That puts more than 1,000 homes, cottages and commercial buildings, 17 lighthouses, and 10 bridges at risk over the next 70 years.

“The research that we put into visualizing sea-level rise has raised people’s knowledge and awareness of these issues, and increased their willingness to take action,” says Fenech.

While there’s no way to stop what’s already started, there are some places on the Island where natural solutions can lessen the impact of higher tides and stronger waves.

Working on the original water control structure in the 1980s, when DUC took sole management of Fullerton's Marsh as a freshwater marsh. © DUC

Restoring wetlands to help cope with sea level rise

Fullerton’s Marsh sits on Fullerton’s Creek near Stratford, P.E.I, where an old rail line bisects 67 hectares of marsh, encompassing a 20-hectare wetland managed by DUC. When those tracks were put in in the late 1800s, the linear earthen mound built to support the tracks acted like a dike, separating the south end of the marsh from salt water flowing in from the Hillsborough River via Fullerton’s Creek.

In the 1940s, the province decommissioned the rail line. In 1950, the province approached DUC for help to convert the marsh into a freshwater marsh on the south side of the tracks. DUC took on the sole management of this marsh in 1980 and has managed the site as a freshwater marsh since then—until staff found that higher tides were eroding the dike faster than it could be fixed.

Construction began on Fullerton’s Marsh in fall 2020 with the removal of the original water control structure. © DUC

The return of salt water to Fullerton’s Marsh

After careful planning, DUC conservation specialists breached the dikes of the freshwater marsh this fall, removing the old steel structure and ensuring the new channel could support a full tidal exchange for the first time in 70 years.

Within a few weeks, there are already noticeable changes in both the plants and wildlife, as the saltwater begins to permeate the wetland, allowing this area to revert to its natural state.

“The bottom sediments are starting to solidify, and there’s certainly a change in wildlife that has been visiting the marsh, with a lot of sandpipers, greater yellowlegs…cormorants, even the odd black duck now frequenting the site,” says Jonathan Platts, a DUC conservation program specialist for P.E.I.

As the biome of Fullerton’s Marsh reverts back to saltwater, the freshwater plants will be replaced by sturdier salt grasses, like spartina, or cord-grass. Tall and reedy, these plants are a key weapon in the fight against coastal erosion.

“When the waves come in, that grass acts as a buffer to lessen the impact of the waves before they hit the shore,” says Platts. “Coastal wetlands are also able to sequester large quantities of carbon. As sea levels rise, so will the marsh. Over time, it will accumulate layers upon layers of sediment, which are rich in carbon. It makes a lot of sense to restore these areas back to salt marsh as it is one of the most effective natural ways to help offset the effects of climate change.”

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The bottom sediments are starting to solidify, and there's certainly a change in wildlife that has been visiting the marsh, with a lot of sandpipers, greater yellowlegs…cormorants, even the odd black duck now frequenting the site.

Jonathan Platts

Exposed mudflats during low tide after breaching the dike. © DUC

Future of Fullerton’s Marsh is bright, thanks to a salt water solution

By August of 2021, Platts expects to see these salt grasses emerging over the area and growing in denser patches. Within two or three years, there won’t be any freshwater plants remaining. And within five to seven years, Platts expects an observer wouldn’t be able to tell the difference between this renewed marsh and a natural salt marsh.

This will be the dynamic ecosystem this area needs. It will host a diversity of wildlife, including herons, kingfishers, marsh wrens, and waterfowl that already make their home in P.E.I. It will act as a coastal buffer against rising sea levels and stronger storms and will help to decrease the energy produced by waves, which, in turn, will prevent erosion along the shore.

But salt marsh restoration is one of many solutions we’ll need to deploy along our coasts in the coming years. We’re striving to be a leader in how we conserve wetlands and manage infrastructure on the coast—and we hope others will do the same. We need to start thinking critically about how we develop and live on this small, vital skiff of land in the Atlantic.