It was 6 o’clock in the morning on an overcast July day when I found myself encased in rubber boots up to my waist, slowly sinking into an experiment that might prove to be the future of the Chesapeake Bay. Clumps of broad-leaved marsh grasses burst from the reddish water pooled around my boots as the tide came in at Blackwater National Wildlife Refuge in Cambridge, Maryland. Within a few hours, brackish water would inundate sections of nearby Maple Dam Road, forcing refuge visitors and residents alike to take advantage of their four-wheel drive.
Twenty years ago, this marsh wasn’t nearly so wet. Back then, it looked like your textbook saltmarsh: a dry upland area, which at Blackwater is loblolly pine forest, that transitions on a downward slope towards the sea—first into high marsh that rarely floods, and then into low marsh regularly washed over by tides. The high marsh was dominated by salt hay, a wiry grass that forms a thick blanket and stays dry above the water line. Wind and waves whip the grass into characteristic cowlicks and, occasionally, if you pried one of those cowlicks apart with a stick, you might have found the perfectly concealed nest of a Black Rail.
Not anymore. The 28,000-acre Blackwater NWR has lost an estimated 5,000 acres of marsh since the 1930s, forcing Black Rails to abandon the area. Invasive species degraded the salt-hay blanket while tides and waves, powered by climate change and its attendant sea level rise, broke it down and pulled it to sea. As a result, most of the 5,000 acres of former marsh are now open water better known as Lake Blackwater, and much of the remaining marsh is low and wet.
As the habitat shifted from high marsh to low marsh, the birds shifted, too. From 1990 to 1992, Dave Brinker, now the central regional ecologist at the Maryland Department of Natural Resources, led a survey of Maryland’s coastal plain marshes for the elusive Black Rails, gray-breasted red-eyed mouse-size birds. After midnight, he broadcast Black Rail calls and then waited for the birds to respond. He heard them calling up and down Maple Dam Road, which runs through Blackwater NWR; indeed, he heard them throughout the Chesapeake. They weren't common by any means, Brinker says, "but we found them in more places than anybody had ever found them.”
When he repeated the survey in 2006 and 2007, after much of the high marsh that the rails call home had transformed into wet, low marsh, he barely heard any at all. He estimates that only 1,200 Black Rails currently breed on the East Coast. “We had an 85 to 90 percent decline in 15 years,” Brinker told me as we drove through the marsh in July. “And that was a shock to everybody.”
Now an impressive group of conservation partners—U.S. Fish and Wildlife Service, Audubon, The Conservation Fund, Maryland DNR, and the U.S. Geological Survey—are leading a series of experiments to figure out how to save a marsh from deteriorating. If they can identify a method that works and get the cost down, they may just be able to rebuild this fragile ecosystem before it’s completely consumed by the sea.
That morning, the partners gathered at Shorter’s Wharf at Blackwater NWR to celebrate the completion of their most ambitious marsh restoration experiment to date. This past December, 26,000 cubic yards of sediment dredged from the Blackwater River were mixed with water (80:20 water:sediment ratio) and sprayed across 40 acres of inundated marsh right behind the dry patch where we stood. At any given spot, 4-6 inches of sediment should have accumulated, raising the land to high-marsh elevation.
Then, 213,000 clumps of grass were planted into the newly dry land to hold the sediment in place. On that final day as the group met, landscapers extracted each plant from stacked pallets and pushed them, one at a time, into the sediment with muddy fingers, moving through a dozen plants or more per minute. Finally, the grueling work of moving earth and planting hundreds of thousands of marsh plants was done. Matt Whitbeck, a wildlife biologist with Blackwater NWR, called the project “the most effective conservation planning, unprecedented in my career.”
We visited a completed plot where one plant sprouted every foot or so. Many looked brown and dead; it was frankly a bit underwhelming. Then one of the landscapers pried up a grass clump to reveal white and green roots beneath the soil—a sign of new growth. “It’s very shocking to go from being covered and babied in a greenhouse” to roasted by the sun and whipped by saltwater, he tells me. “It’s very common for them to brown out and then come back green like this.”
Marsh grasses are hardy plants by definition and should grow quickly, their roots spreading beneath the sediment and sending up new shoots. This should stabilize the soil and prevent additional erosion. But up in the drier, higher areas, the partners’ goal is more ambitious: They want to transform low marsh back into high marsh to recreate salt-hay habitat for Black Rails.
It wasn’t until 2002, just 15 years ago, that biologists with Blackwater NWR caught on to the severity of the marsh loss. Alarmed, they recognized the need to reclaim the 5,000 acres of lost marsh at Lake Blackwater, but they didn’t know how to do it. On a two-acre plot, just across Maple Dam Road from Shorter’s Wharf, they led an experiment with the Army Corps to try and fill in an area that had converted to open water. But recreating the lost land just wasn’t feasible: They estimated it would cost several billion dollars for 5,000 acres, and that’s without considering additional losses from erosion and sea level rise.
Since then, the urgency has only increased. In 2012, Dave Curson, Audubon Maryland-DC’s director of bird conservation and the driving force behind the restoration efforts, led an assessment of the Chesapeake’s marshes with USFWS biologist Whitbeck and Erik Myers of The Conservation Fund, among others. The results confirmed his worst fears. Sea levels were expected to rise by three feet by 2100—bad news for the marshes. “They’re likely to be completely drowned and eroded by the end of the century,” which is faster than anyone anticipated, he says.
Thanks to this initial experiment at Blackwater NWR, the partners knew that they couldn’t recover marsh once it’s gone. Instead, they aim to save the best remaining marshes. In the 2012 report, Curson identified a horseshoe of “the most intact and the birdiest marshes” in the area. “If we can keep 30,000 acres, I think we’ll be doing pretty well,” he says. “Right now, this big marsh complex is around 70,000 acres. So we’ll say goodbye to 40,000 acres and try to keep 30,000.”
First, though, they have to figure out how to keep one acre—much less 30,000. The just-completed effort at Shorter’s Wharf is one of several experiments underway to identify the best way to save a marsh. “What we’re trying to do here is not just try to lengthen the life of the marsh by raising its elevation, but raising it to a point where we can actually convert it back to that high-marsh vegetation,” that salt hay, Curson says. This is necessary and possible because Blackwater isn’t just eroding at the edges where the marsh meets the sea; it’s also eroding from the inside out—a process that isn’t typically considered in models of salt-marsh erosion.
“What you actually have [at Blackwater] is an enormous complex mosaic of different vegetation patches that doesn’t really show typical zonation,” Curson says. “Instead of erosion at the edges where the shoreline is, you just have the submergence of the whole system. The erosion is actually little holes that open up, and it’s like Swiss-cheese interior erosion. So it’s way different from the textbook saltmarsh.”
The marsh is eroding in interior patches because of a few recent man-made threats. Nutria, an invasive rodent released around the Chesapeake for fur trappers during the last century, likes nothing more than to devour salt hay from its roots—and by the late 1990s, its population ballooned to nearly 50,000 animals. Those roots hold the sediment in place, and without them, the soil collapses and erodes quickly with each passing tide.
The rodents are so damaging that, in 2002, Congress authorized $4 million per year for five years to eradicate nutria from Maryland and Louisiana. Marcia Pradines, manager of the Chesapeake Marshlands NWR Complex, isn’t ready to declare them eradicated yet. “But we haven’t seen any in two years, so that’s pretty amazing,” she says. Still, their damage is done; they converted thousands of acres of high marsh to low marsh and open water.
At the same time, sea level has risen in the Chesapeake from a combination of geology and humans’ carbon-dioxide exhaust, intensifying marsh erosion and bringing storms and their surges closer inland. In 2003, flooding from Hurricane Isabel pushed saltwater high into the marsh, as high as the upland loblolly pine forests. Saltwater soaked into the dry ground and into the pines’ roots, killing them. Now, stands of pallid trees known as "ghost forests" fringe the marsh, serving as sentinels of change as their dead roots slowly loosen their hold on the soil. When those dead trees fall, the sediment collapses beneath them, sometimes falling several inches.
Water then pools in these root-less holes and spreads outward, eroding the marsh from the inside out. Swiss cheese, indeed. “It’s amazing how quickly it’s happening,” Curson says. Just two years ago when he did marsh surveys, he’d fall into a deep, muddy hole—the most jarring evidence of the rapid erosion—about five times per day. Now, it’s more like 20 times per day. “The whole marsh is falling apart rapidly,” he says. “The root mats have just disintegrated so much more than one year earlier. We’re catching this place just in the nick of time.”
Spraying dredged sediment in a thin layer and planting grasses, like at Shorter’s Wharf, is one way to save a marsh. At nearby Farm Creek Marsh, a 700-acre plot owned by Chesapeake Audubon Society, the partners are leading another experiment: Instead of raising the land, they plan to remove the water. “One of the things we’re going to do is dig channels to help the marsh drain and see if that restores the patens [salt hay] and the high marsh,” says Hugh Simmons, president of Chesapeake Audubon Society and National Audubon Society board member.
We visited Farm Creek Marsh that afternoon and, let me tell you, it is a very wet place: We needed those waist-high waders as we slogged through several feet of water pooled in rotted marsh. With each step, my boot broke through what used to be a matted marsh-grass blanket, then plunged through a foot or more of mud until the clay bedrock caught my plummeting foot. Each time, it felt like a miracle. Somehow, Simmons deftly maneuvered through the muck with an enormous camera to document the marsh’s vegetation before the experiment begins.
Al McCullough, an ecological engineer at Sustainable Science LLC, describes the channel digging as “doing a coronary bypass” on the marsh. Maryland DNR will dig the channel—an extension of a natural tidal creek—to connect the wettest parts of the marsh to the sea and, if it works, drain the pooled water. To track its success, a group of partners—Audubon, USGS, Maryland DNR, and McCullough—will monitor water levels and vegetation throughout the marsh. Small bags of buried peat will capture any new root growth, allowing the scientists to quantify how much new grass (if any) sprouts after the marsh is less waterlogged. To pay for the work, Curson has raised $450,000 from the Wildlife Conservation Society’s Climate Adaptation Fund, the National Fish and Wildlife Foundation, and the France-Merrick Foundation.
Farm Creek Marsh has taken a leading role in the experiments because this is the last place Black Rails were known to breed. But it’s been a long time since anyone heard their characteristic “ki ki kerr” call, which is easily distinguished from the other three rail species (Virginia, Clapper, and King Rails) that nest along the Chesapeake by its dropped pitch on the final note. During this nesting season, Curson placed audio recorders (donated by Chesapeake Audubon Society) around the marsh, set to record from sundown to sunrise, to capture any errant Black Rail calls. He estimates he has about 800 hours of audio files to analyze from five recorders.
The Black Rail’s vanishing act compelled the USFWS, earlier this year, to examine whether the species warrants listing under the Endangered Species Act. If the agency decides to list it, the marsh restoration experiments—and especially the one that works best—could end up being critical to the elusive species’ survival. “If something like this [marsh restoration] works, and you have a species that you’re trying to recover, it gives you a management technique that we can apply to landscape scale,” Brinker, the Maryland DNR biologist and original rail surveyor, says.
The Saltmarsh Sparrow is in a similar position as the Black Rail. It also nests beneath salt hay and is losing ground rapidly as eastern marshes deteriorate. The future survival of these species requires a method for restoring marsh, and one that doesn’t cost too much money. “It’s expensive to do that, to try and get the right habitat that you need to mitigate the losses of Black Rails and Saltmarsh Sparrows,” Brinker says. The Shorter’s Wharf restoration project costs over $1 million—$1.1 million for the sediment application and $200,000 for the plants—for