Environmental News in Southern New England

Wenley Ferguson of Save The Bay is leading a swamp relocation project at Sapowet Marsh in Tiverton, Rhode Island, USA. The goal is to slowly drain pools, some of which are more than 18 inches deep, to protect the marsh grass and Stop erosion. (Caitlin Faulds/ecoRI press photo)

TIVERTON, RI—The grass is dying. Clusters of broken, bare stems stand in a shallow, salty pool, patching together low-lying swamps.

The slow baldness cannot be seen from the asphalt road of Seapowet Avenue, hidden behind a thick reed curtain. But standing deep in the peat, surrounded by the smell of rotting sulfur, the bare ground clearly proves that steady saltwater creep is occurring in the swamps of Rhode Island.

Spartina alterniflora (Spartina alterniflora), or light grass, is known for its salt tolerance and is a common feature in saltwater marsh environments.

"They can grow along the edge of the bay and are submerged twice a day, but they cannot grow in standing water," said Wenley Ferguson, who holds a shovel in his hand. In the surroundings, sunlight flickered from the pool, unable to be discharged, and slowly increased with each high tide.

Since 1929, the average sea level in Rhode Island has risen by about 1 foot. The storm surge and high tide have advanced inland. Generally, swamps respond to rising high water lines by matching their migration inland.

But with the sea on one side, and a dense network of roads, developments, arable land, and invasive species on the other—and the sea level is accelerating—the Sapovet Marsh has nowhere to go.

But Ferguson, Director of Habitat Restoration to Save the Bay, is working to save the swamp from that saltwater grave.

For more than five years, Ferguson has been working with the Rhode Island Department of Environmental Management (DEM) in the Sapowet Marsh Wildlife Management District, a 260-acre state-owned property.

Over the past 75 years, more than 90 feet of coastline erosion has occurred on the edge of the coast of Sapowet. Under Ferguson's supervision, Sapowet has become the location of the state's largest swamp migration promotion project—a small counterattack against the forces at play.

"When I talk about facilitating swamp migration," she said, "it's a bit like preparing land for swamp migration."

As early as 2017 and 2018, Save Bay and DEM worked with the Tiverton Conservation Commission to restore 9 acres of coastal grassland and rebuilt coastal sand dunes on the north side of the marsh to slow erosion.

Now, work has moved to the west and southeast sides of the swamp-and the strategy has been changed to match.

Save The Bay intern Betsy Smith (left), DEM non-gaming biologist John Herbert, middle and URI graduate student Lucianna Faraone Coccia clear a trail on Sapowet Marsh.

The roots of grasses along the western front line are tight, but they are easy to cut. With a stomped foot, the shovel sank from the mud, and water accumulated on the toes of Ferguson's black rubber boots.

Ferguson said it was a warm and sunny day in November—it was too hot. She packs up for a cool autumn day and wears a blue wool sweater, but 60 degrees means she will sweat by noon.

Earlier this week, Ferguson and a handful of DEM employees and volunteers used shovels and small excavators to dig a woven network of waterways in the swamp. These shallow creeks will provide a route for the pooled water to Narragansett Bay, allowing the area to drain slowly.

Ferguson said that if the root zone of swamp plants can be slightly dry, they will "grow healthy and happy." Healthy plants build stronger foundations, and stronger foundations make coastlines more resistant to erosion and sea level rise.

But "we don't want to exhaust it too quickly," she said. It's been three days since they dug the first waterway, and the water level only dropped a little, revealing a few inches of bare mud-exactly as planned.

The stagnant water is thick with loose sediments and bacterial mats on it. If the water rushes out all at once, these sediments will pour into the bay. It is best to dig in stages, let it settle in the swamp, and keep it as high as possible.

They came back on this day to adjust the flow channel and excavate areas that were naturally blocked by the silt. Save the Gulf volunteer and Lucianna Faraone Coccia, a Master of Environmental Science student at the University of Rhode Island, shoveled a pile of grass roots.

"If it were there, it might block the entire river," Faraone Cocha said, glancing down, and pointed out that a fiddler crab was groping along the river with its unbalanced claws.

With each shovel full, the water flow gets stronger and stronger, and the peat pile next to the runner gets bigger and bigger.

"This is technically considered filler," Ferguson said, and threw another peat at the pile of peat next to her. "In fact, we left the peat in the swamp, and we created these small islands."

These islands are about a chunk of peat thick—about 6-12 inches, not too high, Ferguson said—but that small elevation is “like a mountain in a swamp.”

Ferguson worked hard to keep the peat in the swamp, obtaining additional permits from the Coastal Resources Management Committee, DEM Water Resources Office, and the Army Corps of Engineers. She said that this kind of micro-topography is essential for a healthy swamp surface.

"These areas will only be higher, and they may recolonize," Ferguson said. "When I say it is possible-they will indeed recolonize."

In a season, these islands will sprout new shoots, or they are high and dry enough to support clusters of tall marsh grass. The tall grass will provide an ideal nesting habitat for salt marsh sparrows.

As healthy salt marshes decrease, so does the number of salt marsh sparrows—a bird that uses a cup of dense marsh grass to build its nest. Ferguson said that these nests were built to withstand the highest moon tides. They have a dome, so "the eggs will float, but they won't float outside the nest." But the area here is often flooded, causing the nest to fail.

"That's why the small islands we are building are very valuable habitats," Ferguson said.

Wenley Ferguson is always looking for clues about what shaped the swamp we see today.

The old ways and legacy lines today's marsh state is the result of human development and marshland intervention over the centuries. According to Ferguson, almost every swamp in the country has some historical influence. They are by no means original.

"Many of them have been manipulated for agricultural activities in this area. Then in recent years, we have built roads along them," Ferguson said. "We conserved them. We created duck habitats and seized them. We filled them."

According to Ferguson, from the 1700s to the 1900s, approximately 50% of the marshes in the area were filled. Agricultural dikes also manipulated the marsh surface, dating back to about the 1600s, when people began to hay in these areas.

"The fresher the marsh grass and the fresher the groundwater level, the greater the value of the hay," she said.

When she digs these channels, Ferguson is always looking for clues about the shape of the swamp seen today. The shovel full of roots means that the dead pool was once a field. The water collected in a straight line may be a sign of the old embankment. The long and straight ditch is probably the remnants of the old mosquito ditch-once used to reduce mosquito breeding grounds, but now it has accelerated the erosion of the marshland.

The exhausting past of the swamp—plus its location in an ancient river valley whose steep valley makes migration of the swamp difficult—illustrates a challenging future.

Ferguson said: "That's why what we are doing today is trying to restore some of the health of the swamp...under the current conditions," Ferguson said, "but always focus on where the swamp wants to go."

An excavator drives into the reeds growing on the eastern edge of Sapowet Marsh.

John Veale, a habitat biologist at the DEM Department of Fish and Wildlife, said as he pushed away the sharp corners of dozens of broken reeds. He said, "Be careful with your eyes when you walk through here." "It might be a bit dangerous. "

Over the past century, invasive reed species—with few native reeds—have used weakened saltwater marsh ecosystems to wreak havoc in North America. The eastern edge of Sapowet Marsh is hidden under Old Main Road and several corn fields owned by DEM, and this is no exception.

In many ways, reeds are the perfect storm. Their feathery seed heads capture light beautifully, but they also capture wind and spread like wildfire. Once the seeds take root, the reeds will grow densely. They almost wipe out animal habitats and win the competition with native grasses.

On the Sapowet Marsh, it is an insurmountable obstacle to marsh migration. Only a few vines bravely stretched tendrils into the bushes. In order to keep the marshes away from the eroding sea, the reeds need to loosen their control. But this is a notoriously daunting task.

"We can't do this with a shovel," Ferguson said. "I mean, it's too difficult. A small piece of reed is one thing. When it swaggers, it's another thing."

Mowing and burning have little effect on controlling reeds, and it soon proved costly to pull them out of the roots. But like a smooth herb, it is easily affected by salt water. If Ferguson can drain the pooled fresh water and promote the flow of tides into the reeds, they may dissipate-native grasses may have a chance of survival.

"We will not remove the reeds, but we can reduce the height and vitality of the reeds by promoting fresh water drainage," she said.

Ferguson is in the early stages of this battle, just making plans. Reeds grow to 10-12 feet tall in some places, covering the location of the ground.

"There is enough water," Ferguson said. "It came from somewhere. I just can't figure out the drain pipe because it is too thick."

She asked for the help of an excavator. Within a few hours, the machine opened up a clearing among the reeds and deepened a natural stream. Once some still fresh water is discharged, it is easier to measure the direction of the water flow.

Ferguson and her team intend to extend the creek and old agricultural ditches — to make better use of past mistakes — but the plan is still being developed. Instead of fixing more errors in a hundred years, it is better to act slowly.

"The deterioration of the edge of the swamp is very significant, in my opinion it is a terrible way," Ferguson said, stopping to point to a group of buffalo passing by the water. "So that's why we must be very careful not to open new openings for this erosion."

Editor's note: The above video was shot by BT Hathaway, the founder of SKYCAM Films in New Bedford, Massachusetts.

Environmental News in Southern New England

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