Suzanne's Mom's Blog

Today I learned a few things about marshes that I didn’t know. For example, they are supposed to be wet but not too wet. In Rhode Island, one important wetland was dying — until it was given a helping hand.

Caitlin Faulds has the story at ecoRI News. “The grasses are dying. Clusters of broken, denuded stems stand in shallow pools of brackish water, making a patchwork of the low-lying marshlands. The slow balding is invisible from the blacktop of Seapowet Avenue, hidden behind a thick curtain of phragmites. But standing boot-deep in the peat, surrounded by the sulfuric scent of decomposition, the bare ground is clear evidence of the steady saltwater creep happening in marshes across Rhode Island.

“Spartina alterniflora, or smooth cordgrass, is notoriously salt-tolerant and a common feature in saltwater marsh environments.

“ ‘They can grow along the edge of the cove and get flooded twice a day, but they can’t grow in standing water,’ said Wenley Ferguson, shovel in hand. All around, the sunlight glints off pools of standing water, unable to drain and slowly growing with each high tide.

“The average sea level in Rhode Island has increased by about a foot since 1929. Storm surges and king tides have pushed further and further inland. Normally, the marsh would respond to the rising high-water line by matching the migration inland. But with the sea on one side and a dense web of roads, development, cultivated fields, and invasive species on the other — and accelerated sea-level rise on its way — Sapowet Marsh has nowhere to move. …

“Ferguson has been working with the Rhode Island Department of Environmental Management (DEM) at the Sapowet Marsh Wildlife Management Area, a 260-acre state property, for more than five years now. … Under Ferguson’s watch, Sapowet has become home to the largest marsh migration facilitation project in the state — a small counter to the forces at play. …

“The cordgrass roots are taut, but they cut easy. Just one stomp and the shovel sinks through the muck, water pooling up and over the toes of Ferguson’s black rubber boots. …

“Earlier in the week, Ferguson — along with a handful of DEM employees and volunteers — used shovels and a small excavator to dig a weaving network of runnels through the marsh. These shallow creeks will give the pooling water a route out to Narragansett Bay, allowing the area to slowly drain.

If the root zone of the marsh plants is able to dry even slightly, they will grow ‘healthy and happy,’ Ferguson said. Healthy plants build up a stronger root base, and a stronger root base makes a coastline more resilient to erosion and sea-level rise.

“But ‘we don’t want to drain it too fast,’ she said. It has been three days since they dug the first runnels and the water level has dropped only slightly, exposing a few inches of bare mud — exactly as planned. The standing water is thick with unconsolidated sediments and topped by a bacterial mat. If the water rushes out all at once, this sediment will pour into the bay. It’s better to dig in phases and let it settle out in the marsh, maintaining as much high ground as possible. …

“Ferguson fought to keep the peat in the marsh. … ‘These areas will just be a little higher, and they might recolonize,’ Ferguson said. ‘And when I say might — they do recolonize.’

“Within one season, the islands will host new sprouts of cordgrass, or they’ll prove high and dry enough to support clusters of high marsh grasses. The clusters of high grass will make ideal nesting habitat for the saltmarsh sparrow.”

Read about other benefits at ecoRI, here.