Saving the salt marsh

By Dustin L uca Staff Writer

IPSWICH — Geoff Wilson stood along the edge of a ditch a few hundred feet into the Great Salt Marsh by Crane Beach, looking into a path filled with water, wooden stakes and twine. Roughly 100 feet from him, a few volunteers packed recently cut marsh grass into an empty ditch that fills with water each high tide.

“Another saying we have on the team is that ‘every marsh was a farm,’” said Wilson, a principal with Northeast Wetland Restoration. “It’s what they needed back then, throughout the industrial revolution, before cars came along.”

Those driving to Crane Beach might not notice, but the salt marsh they’re passing to get to the water is in crisis and not built for adapting to sea-level rise. Areas with manmade ditches either trap water or don’t capture enough of it with each passing tide, triggering all kinds of other processes that aren’t helpful to the marsh system.

See MARSH, Page A6

Lukas Wilson of Northeast Wetland Restoration pushes on a wooden stake that holds biodegradable twine, which holds down salt marsh grass that was used to fill an old drainage ditch in the Great Salt Marsh. Workers with Northeast Wetland Restoration, seen here, are restoring the Great Salt Marsh near Crane Estate.

PAUL BILODEAU/Staff photo

Geoff Wilson of Northeast Wetland Restoration heads out to an area to lead his team in restoring The Great Salt Marsh near Crane Estate.

Using a drone, you can see the mowed salt marsh grass, which is being used to fill the old agriculture drainage ditches in the Great Salt Marsh near Crane Estate. Workers with Northeast Wetland Restoration, seen here, are restoring the Great Salt Marsh near Crane Estate. This part of the Great Marsh restoration is being spearheaded by the Trustees, which owns Crane Estate.

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All the non-natural ditches are providing oxygen a means for getting to peat under the marsh grass, according to Wilson. With so many ditches, oxygen then triggers decomposition. Some marshes around New England have dropped by as many as 9 centimeters in the past 200 years from the impact, as the ocean they absorb twice a day continues to rise.

“These plants don’t want to grow in standing water or saturated peat.

When they do, they die, their root masses are lost, and they sink,” said Russell Hopping, lead coastal ecologist for The Trustees of Reservations. “In both cases of over-draining and under-draining, the whole marsh is sinking. We’re losing vegetation.”

Healing with a lawnmower

But ecologists are saying efforts to heal the marsh (contrary to filling it) are working: Roughly $4 million in projects are targeting thousands of acres of marsh from Ipswich to Newbury, with some finishing up years of restoration as others begin the first of three seasons of grass-cutting and ditch-filling. The groups involved have a goal to cover about half of the 16,000 acres of Essex County marshes by the time they’re done, with ditches filled over a three-year cycle to allow them to stabilize and form peat gradually.

Standing on flattened stretches of marsh grass in between ditches, volunteers mow the grass and then use another machine to push that grass toward and into a ditch. That grass is then packed into the base of the ditch and anchored in place with twine and stakes so it doesn’t get washed out with the tide.

Each year for three years, the ditch is filled once in the same way. With that, three new layers of vegetation are added a year apart, allowing the layer below each new one to begin forming into peat, according to Wilson.

“This ditch we’re closing off,” he said, “we want the groundwater to come up to the growing root system.”

The project represents a marsh-themed mystery, where ecologists are responding to agricultural practices that date back to the first English settlers in the 17th century, according to Wilson. Partners in the projects, which are sharing resources and expertise as they carry them out for the first time, include The Trustees, Essex County Greenbelt, the Parker River National Wildlife Refuge, the U.S. Fish and Wildlife Service, and more. The work is mostly paid for with grants and donations from a host of sources targeting the individual organizations.

“We’ve figured out, with Geoff’s help, how to build some automation in this system to scale up and treat thousands of acres economically,” Hopping said. “This is what these machines allow us to do.”

Turning back the marsh’s clock

The North Shore was colonized by English “planters” or settlers first in 1623, with a short-lived fishing settlement in present-day Gloucester and Rockport.

By 1630, the Naumkeag settlement picked up its present-day name of Salem, Marblehead was celebrating its recent birth, and the planters began extending out to modern-day Beverly, Danvers and beyond.

Once Ipswich saw settler activity, the salt marsh was likely generating hay at a rate of about a ton per acre, according to Wilson. Several ditches were added over time to improve hay yield to as much as three tons per acre.

A “reclamation embankment system” was added in the 1800s to restrict the flow of the tide and better control where salt water went each day, further improving growing conditions.

Records don’t really paint a picture of when many of the ditches were created, but some structures named over time still show up today, according to Wilson.

That gives ecologists a point of reference in understanding what parts of the marsh are natural, and what paths were created by humans centuries earlier.

By the 1900s, the industrial revolution saw the marsh’s use for agriculture end, and those working it simply walked away, according to Hopping. That left all the ditches they created to become occupied by exploding salt-water mosquito populations. The ditches were later modified again to bring pest counts down, according to Hopping.

“All the marshes along New England have been incredibly altered for agricultural purposes, first in the later 1600s, and augmented again in the early 1900s for mosquito control,” Hopping said. “What we’re trying to reverse is the agricultural history, which is still continuing on.”

By filling the manmade ditches and restoring the marsh closer to its natural state, each tide will capture sediment and cause grass to grow taller to compete with the captured sediment, causing the entire system to rise very gradually. It’s a similar approach to sealevel rise and stormwater management to the “living shorelines” built around the region, including along Collins Cove in Salem.

In the meantime, the ocean is rising at a rate of about 3.5 millimeters per year, according to Wilson.

Spartina alterniflora, a particularly aggressive salt marsh cordgrass, can cause the marsh to grow at a rate of anywhere from 5.5 to 18 millimeters per year — far outpacing the speed of sealevel rise. “Marshes naturally will build and accrete. ...

We’re trying to restore the marsh’s ability to do that so it can keep up with sea-level rise,” said Cynthia Dittbrenner, director of coastal and natural resources for The Trustees. “Whether or not our marshes can keep up remains to be seen. The first step is to heal them.”

Contact Dustin Luca at 978-338-2523 or DLuca@gloucestertimes.com. Follow him at facebook.com/ dustinluca or on Twitter @ DustinLucaSN.

Colbie Wilson of Northeast Wetland Restoration rakes in mowed salt marsh grass to fill an old drainage ditch in the Great Salt Marsh. Workers with Northeast Wetland Restoration are restoring the Great Salt Marsh near Crane Estate.

PAUL BILODEAU/Staff photo