A Sweet Solution to a Sticky Problem

When you’re a biologist at a site named for a legendary environmentalist, you feel a responsibility to do your job with the planet in mind.

Just ask Dr. Susan Adamowicz, Land Management Research and Demonstration Area biologist for the Northeast Region of the Fish and Wildlife Service. Stationed at Rachel Carson National Wildlife Refuge in Maine, she is tasked with finding innovative ways to manage wildlife habitat and takes inspiration from the renowned author.

Service biologist Dr. Susan Adamowicz examines Spartina patens, a native salt marsh cordgrass, at Parker River National Wildlife Refuge. (Credit: Steve Droter)

Rachel Carson conducts marine biological research in 1952. (Credit: USFWS)

In 1962’s Silent Spring, Carson, who also worked for the Service, sounded the alarm about pesticides that imperiled wildlife and people alike. She knew that many of the synthetic chemicals used to control unwanted plants and insects were dangerous to more than their targets.

For a healthy environment, Adamowicz seeks other solutions … and hopes she has found one with the help of a University of New Hampshire researcher.

A “Consummate Invasive Species”

Phragmites australis, or common reed, is an aggressive, nonnative marsh grass that pushes out native wetland plants. You’ve probably noticed its tall (up to 18 feet!), feathery, golden stalks in your neighborhood or along the freeway.

Phragmites is plentiful in the high salt marsh of the Great Marsh, the largest continuous stretch of salt marsh in New England. Three thousand acres of the 20,000-acre marsh in eastern Massachusetts lie within Parker River National Wildlife Refuge.

Parker River National Wildlife Refuge, in eastern Massachusetts, protects 3,000 acres of the Great Marsh, the largest continuous stretch of salt marsh in New England. (Credit: Matt Poole, USFWS)

A boardwalk passes through a stand of Phragmites australis at Parker River National Wildlife Refuge. (Credit: Steve Droter)

Phragmites changes the structure of the salt marsh, filling natural channels and tidal pools where waterbirds, fish, and invertebrates find food and safety. Many wildlife species find its dense patches impassable, and in the fall, when the stalks die back, stands of the plant turn to tinderboxes primed for wildfire, putting nearby homes and businesses at risk.

Biologists have long searched for effective ways to control Phragmites. It’s a determined adversary, however. Like those birthday candles that re-ignite, just when it seems defeated, it springs back to life.

According to Adamowicz, “Phragmites is the consummate invasive species. If you cut it or burn it, it comes back. If you can flood it for six months, that might kill it, but flooding is not always feasible.”

Phragmites grows along a marsh at Sachuest Point National Wildlife Refuge in Rhode Island. (Credit: Tom Sturm, USFWS)

While restoring natural tidal flow to coastal marshes is the preferred way to fight Phragmites,  replacing culverts, filling ditches, and improving drainage can take a long time. Treating it directly is necessary to keep it in check in the meantime.

Sadly, there’s been no good way to do that. Herbicides work in certain locations but pose a risk to native vegetation and groundwater — certainly not a solution Rachel Carson would embrace.

So Adamowicz teamed up with Dr. David Burdick, research associate professor and interim director of the Jackson Estuarine Laboratory at the University of New Hampshire, to explore innovative ways to control Phragmites. One of the methods they tested was sweet and simple.

Turning the Tables

Burdick had a hunch that sugar, the same kind you put in your coffee, might be Phragmites’ Kryptonite.

Dr. David Burdick takes notes at Parker River National Wildlife Refuge. (Credit: Gregg Moore, UNH)

Each summer, rising air temperatures and increased plant growth stimulate bacteria in salt marsh soils to convert organic matter and oxygen into carbon dioxide, water, and energy — a process called aerobic (“with air”) respiration. The activity quickly uses up soil oxygen, forcing other groups of bacteria to make energy using anaerobic (“without air”) respiration.

One by-product of anaerobic respiration is hydrogen sulfide gas, a potent toxin for plants as well as people. At typical levels, the gas is not deadly to most native plants, but it can be toxic to Phragmites.

Burdick thought increasing bacterial respiration, and therefore hydrogen sulfide levels, could kill the invasive.

“Because Phragmites is a master at getting oxygen to its roots for its own respiration, we could use this strength to kill it,” he mused. “By elevating soil hydrogen sulfide levels, we might stimulate the plant to oxidize the gas into a strong acid that it may not be able to tolerate.”

While he couldn’t control air temperatures, he could increase fuel for the bacteria — using glucose in the form of table sugar.

Pour Some Sugar on It

Burdick and his team first tested their idea in the greenhouse. They soaked Phragmites plants with bay water for three hours every two weeks to mimic the flooding that high-marsh plants get during the extra-high “spring” tides that come with the full and new moons each month.

Some plants (the control) received only the bay water; others got water with table sugar; still others water with extra salt; and the remaining, water with sugar and salt.

In the greenhouse study, plants receiving sugar or sugar-plus-salt (right, top and bottom) showed clear signs of distress within weeks of treatment. (Credit: Gregg Moore, UNH)

Both the sugar and sugar-and-salt treatments showed signs of stress within weeks and eventually died. Only the plants that received plain bay water or bay water with added salt lived.

The sugar-treated plants had very high soil acidity, possibly caused by sulfuric acid, the product of hydrogen sulfide oxidation. This supported Burdick’s theory.

Next, Burdick and Adamowicz headed to Parker River Refuge to set up a field study in the northern part of the Great Marsh. The research was supported by federal funds for Hurricane Sandy recovery and resilience projects.

Following the greenhouse trial, Burdick and his team tested the treatments in the Great Marsh at Parker River National Wildlife Refuge. (Credit: Gregg Moore, UNH)

They isolated individual Phragmites plants and applied the same treatments as in the greenhouse. Sugar and salt were put on the plants every two weeks, after the spring tides flooded the marsh.

The plants that got sugar had far greater mortality than the other treatments, even with uncontrollable environmental factors, such as rain — a clear sign that sugar is not sweet to Phragmites.

Refining the Technique

Adamowicz is pleased with the study results so far and eager to set up more field trials. She’s exploring ways to treat Phragmites with sugar and salt more efficiently and broadly, perhaps using a backpack sprayer to apply corn syrup at more-frequent intervals than every two weeks.

“This is another tool in our toolbox, and it’s nontoxic to wildlife, which is very desirable,” she said. “The more complicated response to Phragmites is ecosystem restoration, but in the meantime, we need a fast-acting tool to help native plants come back and buy time.”

If Rachel Carson were alive today, she would certainly approve of this environmentally sound method — and just might be thinking, “Sweet!”

Lessons Learned and Put to the Test at Rhode Island Refuge

When Hurricane Sandy hit the Rhode Island coast in late October 2012, Sachuest Point National Wildlife Refuge got hammered. Five years later to the day, the remnants of Tropical Storm Philippe struck New England, bringing strong winds and heavy rain. This time, the refuge was ready, thanks to work by the U. S. Fish and Wildlife Service and its partners.

The Wrath of Sandy

Hurricane Sandy brought heavy rain, wind gusts exceeding 80 miles per hour, and a storm surge boosted by a full moon to Sachuest Point. It wrought havoc on the refuge, chewing up pavement, strewing rocks and chunks of concrete onto the access road, and knocking down power poles. Maidford Marsh was flooded and its outlet to the Sakonnet River blocked by sand.

Restoring power to the visitor center took three months and re-opening the road another three, at a cost of $648 thousand. Thousands of would-be visitors were inconvenienced.

Hurricane Sandy caused severe damage to the access road at Sachuest Point. Credit: USFWS

Fortifying Infrastructure

Following Sandy, the Service worked with partners to repair and armor the access road, bury 7,000 feet of utility lines that run alongside it, and remove 60 utility poles. The work cost more than $1 million and was supported by Federal funding for Hurricane Sandy recovery and resilience projects and a generous $250,000 donation from local partners.

Following Hurricane Sandy, the Service and its partners strengthened the access road by adding armor stone along the ocean side. Credit: USFWS

The last utility pole along the access road comes down. Credit: USFWS

Mending the Marsh

The northern end of the marsh at Sachuest Point was modified dramatically in the early 20th century, when the Maidford River was rerouted and the Connector Road built from one side to the other. The southern end served as the dump for the Town of Middletown until 2004, when trash was removed and placed in a landfill to the west of the marsh.

With the marsh’s natural water movement, or hydrology, altered, the northern end was prone to flooding during heavy rain storms. After Sandy, it was inundated for an extended period, and the Connector Road was underwater.

In 2015, as part of another project supported by Hurricane Sandy funds, refuge staff created new channels in the marsh to improve its hydrology and drain storm water. When they realized more were needed, they contracted with the Woods Hole Group, in East Falmouth, Massachusetts, to study further the hydrology of the marsh. Another channel was added this fall, and staff will continue to assess the situation.

With support from a Hurricane Sandy Resilience grant from the National Fish and Wildlife Foundation, the Town of Middletown, Rhode Island, raised the Connector Road through the marsh to reduce its chances of being overtopped by floodwaters.

In 2015, the Service created additional channels in the marsh to improve water movement and drainage. Credit: USFWS

Following further study of the marsh’s hydrology, the Service created another channel this past summer. Credit: USFWS

A Trial Run

This year’s storm was the result of bombogenesis, which happens when air pressure drops rapidly, intensifying the winds at the center of the storm. While not a hurricane, it brought heavy rain, high winds, and more power outages than Sandy. Due to the moon phase, tides were lower, reducing storm surge.

This time, there was no flooding and no loss of power at the refuge. The access road and visitor center remained open to the public. Cleanup amounted to closing lids on trash bins.

In the northern Maidford Marsh, stormwater drained through new channels and into the Sakonnet River without backing up. The Connector Road remained above water and open to traffic.

“We were hoping that the new channels would improve drainage, and this storm demonstrated that they have,” said Dr. Jennifer White, the Service’s Hurricane Sandy resiliency coordinator.

A #StrongerCoast

It’s hard to make a direct comparison between last month’s storm and Hurricane Sandy, but the conditions presented by the two are strikingly similar. While Sachuest Point experienced high winds and heavy rain during both, the damage to infrastructure and habitat was like night and day.

Knocked to its knees five years ago, the refuge returned stronger, meeting the recent challenge head-on and remaining up and running for wildlife and people.

Taking marsh restoration to a new level

The author at the project site. Credit: Dagny Leonard

As part of “Building a Stronger Coast” month, we’ve asked Erik Meyers, with The Conservation Fund, to share his thoughts on a marsh restoration project that the Fund is leading at Blackwater National Wildlife Refuge in Maryland. Erik is vice president for climate and water sustainability at the Fund.

“But it’s not Yosemite!” friends sometimes blurt out when I speak glowingly of Blackwater National Wildlife Refuge. “No,” I respond, “it’s better.”

Few places on Earth better convey nature’s timeless beauty, productivity … and fragility. Here at Blackwater, soft green marsh grasses spread toward a distant horizon; small salt-marsh birds dart in and out of view; tree islands and forest fringe frame views of the marsh and coastal rivers — all competing for attention with majestic eagles soaring in dramatic Chesapeake skyscapes. Not for nothing is Blackwater frequently called the “Everglades of the North.”

Seaside sparrows nest in the salt marsh at Blackwater Refuge. Credit: USFWS

I’ve learned to look closer, however, and see what’s changing as well. Sometimes the change comes gradually—a ghost forest where there was a healthy stand of pines five years ago. Sometimes change comes suddenly—last year’s solid salt marsh now pocked with small pools of open water. The evolution of this landscape, formed after the retreat of the last major glacier in North America some 10,000 years ago, is accelerating due to the rising level of the Chesapeake Bay and Atlantic Ocean.

Sea-level rise models predict that Blackwater will be dramatically altered over this century, much more than at any point in recent history. An assessment by The Conservation Fund and others signaled the need to act now to hold onto these marshes, including ensuring space for the marsh to relocate, or “migrate,” inland as sea level rises. As important as they are to wildlife, salt marshes also serve people, buffering storm surge and wave action and absorbing flood waters.

In addition to offering important wildlife habitat, salt marshes like the one at Blackwater absorb floodwaters and storm surge, protecting coastal property. Credit: Whitney Flanagan

A core project team of staff from the refuge, Audubon Maryland-DC, and The Conservation Fund, along with strong technical and citizens advisory groups, developed science-based, comprehensive strategies to help the marsh adapt. There were three objectives:

• Hold the most-promising marsh-migration corridors in open-space uses.
• Help former upland areas become new, high-quality marsh.
• Slow the loss of existing high-quality salt marsh in strategically targeted areas.

A grant from the National Fish and Wildlife Foundation, supported by federal funds for Hurricane Sandy recovery and resilience, provided an unprecedented opportunity to apply and evaluate these strategies. The centerpiece of our project, completed in 2016, involved using Blackwater River sediment, which is mostly disintegrated upstream marsh, to raise the surface level of 40 acres of strategically located Refuge salt marsh.

Depositing Blackwater River sediment on the marsh to raise its elevation. Credit: Dave Harp, Chesapeake Photos

Pioneering scientific research suggests that native marsh grasses are most productive at a higher point in the tide range. With the elevation of the marsh surface, we expect native grasses to increase root growth, or “biomass,” and “lift” themselves higher over time. Maintaining productive native marsh plants is key to helping marshes rise along with future sea level.

This slideshow requires JavaScript.

While we will continue to monitor and evaluate the project, to date, the results have exceeded our expectations. Added sediment settled out to target levels. Existing native grasses have flourished, and new plants added over the summer have taken root. Breeding pairs of seaside sparrows are already back using the site.

These outcomes are due to incredible partners at the refuge, the Fish and Wildlife Service Northeast office, Audubon Maryland-DC, and other federal and state agencies — a social ecosystem nearly as vital as the natural system we’re all trying to conserve, enhance, and adapt.

So, no, it’s not Yosemite; it’s better.