Project could hold key to coastal marsh preservation

It’s late July at the mouth of the Housatonic River. Wind gusts out seaward carrying columnar rain clouds. Lightning flashes on the horizon. Waving meadows of tall grasses with summer wildflowers give way to salt grasses.

Biology professor LaTina Steele of Sacred Heart University leads a crew of undergrads from a van. They scurry down to the Stratford Point shoreline to beat the weather. Steele is part of a research team studying how to restore lost salt marshes. Stratford Point is a major test site.

“We’re getting oysters coming into the site… we’re seeing a lot of them over there,” said Steele, pointing to several lines of artificial reefs in the distance. “We’re documenting that there aren’t that many here. After restoration we’ll probably start to get more.”

As the rain sluggishly chugs toward the team, they set to work digging up samples of sediment to bring to the lab. They’ll examine the soil for shellfish and other invertebrates, taking a census of the life here before they enter the next phase of their restoration work.

In the background a young boy of about 12, the child of one of the student researchers, enthusiastically asks the scientists to tell him what kinds of shells he’s finding.

Someone tells him he’s found oysters growing on other oysters. There weren’t oysters here before. They’re a testament to the work done here.

Stratford Point used to belong to the Remington Gun Club. For roughly 65 years the marshes had been used as their skeet shooting range. Three million pounds of lead shot were fired into the marsh, contaminating the soil and Housatonic estuary.

Lead cleanup, which involved excavating and replanting the contaminated marsh, occurred around 20 years ago but the dig functionally destroyed the marsh.

“Back then the only technology was to dig up the marsh, all the substrate, run it through a jig and try to pull out the lead shot,” said Min Huang, migratory bird program leader for the state Department of Energy and Environmental protection. “We didn’t get all the lead, but it destroyed that marsh.”

Stratford Point is a case study in shoreline habitat restoration. The projects being done here by Sacred Heart, National Oceanic and Atmospheric Administration, the Environmental Protection Agency, DEEP and others could hold the key to preserving sensitive coastal areas from the effects of climate change, namely intense storms and sea level rise.

Scientists know now that coastal marshes serve as buffers from storms, nurseries for fish, homes for crabs and birds and sinks for carbon. Preserving them is critical for maintaining the shape of the coast, the economy and biodiversity.

Coastal marshes have long been under threat from development and human intervention. In the past, coastal marshes were considered mosquito-infested wastelands and nuisances. Starting in the colonial period and until the 1960s state and local policy centered around marsh drainage and removal. Even as policy shifted, auto-centric, suburban sprawl development patterns continued to put stress on coastal marshes as developers pushed into coastal areas. Now it is extremely rare to find coastal marshes without neighborhoods or vacation areas on top of them.

Climate change heightens the pressure on these environments. Increasing storm severity threatens to wash these ecosystems away. Rising sea levels threatens to drown them, turning salt marshes into barren mud flats. The altered hydrology from decades of projects means more invasive plants and less sediment recharge.

“We’ve built basically right down to the edge of the marshes,” said Huang. “In areas where the marsh might migrate if you have houses there you have homeowners building bulkheads to protect their property.”

In effect, the marshes are being squeezed between rising seas and coastal infrastructure. There’s just no place for them to go.

In 2014 a team led by Sacred Heart biology professor Jennifer Mattei installed several lines of reef balls near Short Beach on Stratford Point. The goal was to jumpstart a reef ecosystem that would protect the marsh while growing new shellfish colonies.

“It’s all about getting those habitats back into places where they are missing,” said Mattei. “It’s working as planned because the oysters are recolonizing, and the oysters are going to protect the toe of that marsh.”

Reef balls are hollow balls made of Ph-balanced concrete with large holes to allow animals and water to pass through them. They mimic the structure of a coral or shellfish reef, absorbing wave energy and protecting tender shorelines. In the process they provide a place for oysters, salt grass and other sea life to reestablish without being washed away.

“When we started it was only 5 percent left of what was there,” said Mattei. “Those homeowners behind the marsh don’t realize what they’re losing.”

The balls were installed to protect the salt marsh which had rapidly eroded away following an earlier contamination cleanup effort.

Scientists and state and federal conservation officials are testing out how best to build marshes up before they’re lost for good. Huang said that the state had been working on several projects to restore marsh connectivity with the sea. Roads, culverts and dykes had created choke points where high water could not drain, drowning marshes in salt water ponds.

“What you get is water being trapped inland,” said Huang. “You don’t get complete flushing of the marsh.”

Beth Lawrence, a professor of biology at UConn, has been working across the way from Stratford Point at Great Meadows Marsh and at other salt marshes up and down Long Island Sound. Her project looks at placing thin layers of sediment on top of marshes to keep them from drowning in high seas.

“We’re testing how different sediment textures affect the vegetation,” said Lawrence. “Ultimately does it promote coastal resilience in our era of rising seas?”

Lawrence said that for some parts of the marsh it was a race against time. There are two kinds of marsh, high marsh and low marsh that have completely different plant and animal communities at slightly different elevations. The high marsh, which is important nesting ground for birds, is rapidly disappearing.

“The idea of building the marsh vertically, adding sediment to the surface might help save our marshes in at least the short term,” said Lawrence.

Lawrence said that ideally thin-layer placement would use dredge materials from local harbor or river dredge navigation projects to help re-charge the marshes. In unaltered conditions those sediments would have been deposited on marshes over time.

James Turek, a restoration ecologist for NOAA who was part of the restoration effort on Stratford Point said that while it would be ideal for dredging sediments to be used to restore coastal habitats it wasn’t as simple as dumping silt on a marsh. Apart from the inter-agency logistical issues and Congressional funding constraints sediments just aren’t all equal. In quiet stretches of river, anoxic sediments can harbor dangerous sulfuric material.

“What happens is the bacteria suck out all the (sulfur) and then you have hydrogen sulfide generated,” said Turek. “When you expose the air to hydrogen sulfide it causes a chemical reaction that generates sulfuric acid.”

You can’t dump sulfuric acid-laced sediments on anything and expect it to go well for a restoration project or for human health, Turek explained.

“The source of those sediments and their quality needs to be taken into consideration,” said Turek. He said that he’d prefer to have dredge material dumped nearer to shore where they can naturally wash up and recharge beaches and marshes.

Mattei’s living shoreline gets around this problem somewhat by giving sediment the chance to settle out of the sea, effectively recharging the marsh without worrying about trucking soil in. Since 2014, the height of the sediment has grown by over a foot, according to Mattei. The marshes have begun to grow over the first line of reef balls farther out into the estuary. The deeper artificial reefs have allowed oysters and mussels to recolonize too, providing further wave-break protection for the shore.

“This is demonstrating that we can have shoreline protection,” said Mattei. “We can jumpstart the reef-making process.”

Mattei explained that an under-appreciated part of keeping the shorelines safe was maintaining shellfish reefs deeper out in the water. Shellfish reefs disburse wave energy and soften storms with the sheer mass of their bodies. Their filter feeding cleans the water and allows light to reach seagrass beds. All of this contributes to maintaining protected shorelines and fish habitat.

“Historically this whole area used to be covered in oyster reefs,” said Mattei. “In New Haven there used to be huge oyster houses and people would harvest and eat oysters right on the shoreline.”

She explained that with climate change accelerating the pace and frequency of major storms that now was the time to jumpstart reef making. Without restoring natural shore protection, increasingly powerful nor’easters would scour the coast and erode marshes away.

Statewide, protecting marshes from this means restoring drainage where culverts and flood protections had accidentally made saltwater ponds on marshes. Hammock river, in Clinton is on the list for removing tidal restrictions. A pair of living shoreline projects are in the works for Long Warf Park and East Shore Park in New Haven.

For Mattei the next phase is installing oyster castles farther out into the water. Oyster castles are, basically, concrete Lego bricks that can be assembled by hand at low tide out in the water. They’re easier to install than reef balls and perform a similar function, creating a foundation for reef growth.

She’s also excited that her project is serving as a model for other states to adopt. Earlier in August, she hosted a delegation from the New York State Department of Environmental Conservation who are hoping to replicate her success at a decaying marsh near Westchester near Playland.

“I’m hoping that more people understand, particularly in the political realm, the value of these habitats,” said Mattei. She said that she’s seen people come around to over time, even though there’s still pushback. “It just takes time, though I’m a little impatient.”