Our Marshes Are Dying





Hartford Courant, July 22,2007 (updated May 2, 2014, see endnote)


BRANFORD –Peter Banca looked out a window of his Stony Creek home, across his sloping lawn to the green swath of marsh named for his father, a look of surprise on his face.
“I had no idea,” he said when confronted with the prediction that the marsh would disappear in a few decades. But he knew the implications immediately.
Banca marsh has been losing 10 or more feet of its seaward edge each year to what some scientists call sudden wetland dieback — a so-far unexplained phenomenon in which marsh grasses die off, leaving mud, pocked with holes, to wash away with the tide. Even away from the edge, pockets of marsh grass are fading into barren mud sinks.
The fate of Banca marsh, and of tidal wetlands around the world, may be tied to rising sea levels and global warming in intriguing ways. The life of these simple grasses ebbs and flows to the moon’s orbital cycles, to the pressing influence of humans and perhaps even to a fungus that sails across the Atlantic Ocean on dust storms kicked up by drought in Africa.
“Sudden dieback” may be a misnomer: For more than a decade scientists have been uncovering troubling changes in marshes around the world and trying to decipher the causes. So far, there is no one simple answer.
Along the Gulf Coast of Louisiana, hundreds of thousands of acres have died off, done in, perhaps, by a combination of drought, heat, fungus and rising water. Around Hudson Bay, an exploding population of lesser snow geese has denuded a large area of sub-Arctic wetlands. On Cape Cod, hordes of purple marsh crabs creep out at night to munch on the cordgrass.
Banca and his mother, Florence, donated the 5.25-acre marsh next to their home to the University of New Haven a decade ago to protect it from development. That may turn out to be a moot point if the marsh dies.
“I hope we don’t see that day,” said Banca, 58. “But it’s going to change the character not only of my own home, but of the whole Connecticut shoreline.”
Losing a marsh takes away not only nice views, but also a marine nursery for oysters, shrimp, crabs and fish, and a feeding and nesting area for birds and other wildlife.
These coastal wetlands trap sediment and filter contaminants from groundwater and surface water runoff. And marshes serve as a physical barrier between the sea and the billions of dollars worth of homes, businesses and infrastructure jammed along the Connecticut shoreline — a shock absorber for flood tides and storm surges.
This is a front line in the battle over global warming: a place where the theories about how things change and what might happen come up against the practical realities of daily life.
The rise in sea level is expected to accelerate over the coming century due to thermal expansion and melting land-based ice, according to projections from the U.N.-based Intergovernmental Panel on Climate Change. It could be a matter of inches or several feet, depending on what climate models you look at.
Even a few inches could spell the end of much of the world’s coastal wetlands.
“I just wonder if there’s anything we can do, as a society and a nation, to protect ourselves,” Banca said.
Connecticut’s salt marshes have been developing for thousands of years, since glaciers from the last ice age receded, pouring their melting water into the sea and leaving behind the basin that is now Long Island Sound.
As long as the sea rose slowly, marshes could keep pace. Saltwater-tolerant grasses colonized newly deposited sediment, in turn trapping more sediment and building the marsh. Upper marsh plants spread inland as the creeping sea pushed at their borders.
But now the sea may be rising too quickly for marshes to adapt, and manmade barriers — buildings, parking lots, roads and train tracks — have cut off the marshes’ inland retreat.
At least since the arrival of European colonists, humans have been fiddling with the marsh equation. They cut ditches to drain the marshes and cultivated salt marsh hay for their cattle. Wetlands were filled for development. In the 1930s, federal work projects dug more ditches in an ultimately futile effort to control mosquitoes.
Shoreline development, from shopping centers to subdivisions, has increased the amount of fresh, nutrient-rich water running into the marshes. It’s also encouraged the spread of an invasive reed, phragmites. The plant’s tall, densely packed stalks have taken over large areas of high marsh, crowding out native plants and many animals.
A belt of phragmites lines the upper edge of Banca marsh. Behind it, a former trolley line, now a hiking path, cuts through the marsh. Farther back, commuter trains whoosh by on the Amtrak line. Roads curve through clutches of houses mounted on the shore’s stony ledge.
From a deck at the edge of his lawn, Banca can look south past the rocky fingers of Stony Creek, through the Thimble Islands into the Sound.
“Marshes have kind of come into their own,” Banca said. “In years gone by, they were treated as dumps.”
As Banca tells the story, the grassy rise where his house sits was once a pile of stone debris from a nearby quarry, where his grandfather, Alexander, worked. Alexander Banca came to America from Italy in the 1890s and made his living in stone work and freight hauling on the trolley line.
Alexander’s son, Attilio, befriended a World War I veteran who was convalescing at a home nearby. Jules Andre Smith was an artist and architect, one of eight men sent by the U.S. Army to Europe as sketch artists to record life on the front lines. The experience cost him a leg.
Attilio and Smith asked the elder Banca to sell them the rock dump next to the marsh so they could build a studio and art gallery. They obviously saw something the grandfather did not.
“He said, ‘You’re crazy! Why do you want to build down by a swamp?'” Peter Banca said. Then he gave them the land.
Smith founded The Research Studio in central Florida, an artists’ colony now called the Maitland Art Center. Attilio Banca ran the gallery in Stony Creek and later in Maitland. When he married in 1936, he and Florence adapted the studio and gallery as a home, and spent their summers in Branford and winters in Florida.
In a small stand of trees just above the marsh sits a rock with a bronze plaque on it: in grateful memory of Attilio Banca.
At low tide, the outer edge of Banca marsh forms a ragged outline. Stems of spartina alterniflora — the cordgrass that dominates the lower marsh — stick up from a shelf of dark peat a foot or two above the mud flat.
University of New Haven Professor Roman Zajac stood in the grass one day this spring, black Wellingtons on his feet and a yellow, book-size global positioning device in his hand. He waited for the requisite five satellites to pop onto the GPS screen, then set out to map the marsh.
Zajac, 58, is a benthic ecologist — he looks at what’s on and in the oceans’ sediments. He spent much time as a youth exploring Hammonasset Beach and Rocky Neck state parks.
He and some of his graduate students are trying to understand why — and how fast — Banca marsh is eroding. On this day, Zajac held his GPS reader waist-high and stepped out as far as he could to trace the edge of the grassy shelf. Every few seconds, the GPS box would beep, recording a position.
In a healthy marsh, cordgrass holds the gooey gray sediment together with its roots. Along the edge of Banca marsh, stretches of bare mud are pockmarked with holes — cavities left behind by dying cordgrass. In some places, hummocks of peat with tufts of grass still clinging to them have broken away.
Soon the tide will wash away these chunks and the bare mud at the edge, and the green marsh will become a mud flat.
The predicted rise in sea level in response to global warming will certainly hasten this process.
“Most coastal scientists would agree this is what’s going to happen over the next 10 to 20 years,” Zajac said. “How much we lose and how quickly we lose it becomes the question.”
By Zajac’s calculations, about a quarter of the marsh has disappeared. He estimated the 3-acre area he is mapping will crumble into mud flat in 38 years.
Zajac said the pace of erosion at Banca may actually have slowed as the crumbling edge reaches higher marsh, where thicker peat offers more resistance. But another dynamic is at work there. The dominant high marsh grass is turning brown and dying.
Using laser-generated images taken from aircraft crisscrossing the marsh, Zajac and his crew have created precise elevation maps showing where the marsh appears to be sinking. In these “wet” areas, where the high tide now creeps in more often, they see high marsh grass dying off.
Zajac is not sure what is killing off the grasses. Scientists elsewhere are puzzling over the same problem, and in some cases, they are finding very different answers.
Mark Bertness, a marsh ecologist from Brown University, does not like to speculate about causes.
“Science is not about hunches and science is not about having a pet hypothesis,” Bertness said. “Science is about figuring it out.”
What he figured out on Cape Cod is that large numbers of the tiny purple marsh crab, sesarma reticulatum, were decimating the marsh grass.
“Humans are doing something to crank up these crabs,” he said. “I don’t know what at this point, it could be over-fishing,” which may have eliminated the crabs’ natural predators. “I don’t jump to conclusions.”
“His preliminary results are astounding,” acknowledged Stephen M. Smith, a plant ecologist at the Cape Cod National Seashore who is working with Bertness. Smith estimated as much as 12 percent of the Cape’s marshes have died off in recent years.
Smith recently found more surprises. After examining old aerial photographs over the winter, he and fellow researchers concluded that what they had been calling sudden wetlands dieback has been going on for at least two decades.
“Perhaps the reason it’s called sudden dieback is because suddenly people noticed it,” he said.
Further, some of what they initially thought was low marsh dying off turns out to be the remnants of higher marsh areas that have been dying back from their seaward edge. That could be because higher tides have been flooding them more often with salt water. The same phenomenon has been seen in the past year at the Hammonasset marshes in Madison.
Bertness sees parallels to the crab story around Hudson Bay and in the U.S. Southeast. In a 2004 paper published in American Scientist, Bertness and two colleagues described how the lesser snow goose has wreaked havoc in the far north.
The geese breed in the lowlands around Hudson Bay, where they feast on the marsh grass. As long as there were not too many geese, their eating habits and frequent defecation, adding nutrients back to the soil, had a positive effect on the grasses.
At one time the geese spent winters mostly grazing in the coastal marshes of Texas and Louisiana. But starting in the 1960s, the introduction of high-yield crops and nitrogen-based fertilizers in American agriculture in effect laid out a smorgasbord of rich food for the birds. The population exploded from an estimated 600,000 to 3 million or more.
Up north, the impact was devastating. In 10 years, Bertness said, the geese ate more than 247,000 acres, about a third of the Hudson Bay coastal marsh vegetation.
In the salt marshes of Georgia and South Carolina, Bertness and colleagues pegged marsh loss to snails. Normally, blue crabs and other predators eat marsh snails that in turn graze on the cordgrass. The snails also eat a common fungus that grows on the grass — fusarium. In the absence of predators — through over-fishing or other changes — the snails can decimate the marshes, Bertness and his colleagues said.
Fusarium, along with other factors, is a suspect in recent diebacks of Louisiana’s salt marshes. While Louisiana’s marshes have been subsiding and regenerating for a long time, scientists say the recent diebacks are more extensive and sudden than previously observed.
Everywhere he looks, Bertness sees the hand of man.
“What I am most alarmed about is that every case we know of is triggered by human disturbance,” he said. “The question is what are the triggers, and what we can do about it?
“It’s important that the general public get a real feel for what could be going on. It’s really important to get this right.”
Wade Elmer knows about fusarium. A plant pathologist at the Connecticut Agricultural Experiment Station in New Haven, he has been studying the fungus and related plant diseases in agricultural crops for 20 years.
Now, with a grant from the Long Island Sound License Plate Fund, he is looking at the marshes. He and two colleagues slogged around the Banca marsh mud in June to collect samples of cordgrass. By looking for evidence of fusarium in both the healthy marsh and the parts that are dying, he hopes to better understand what role the fungus plays.
This is not a simple task: There are more than 200 species of fusarium. What Elmer has found here so far is a different species from one tied to the diebacks in Louisiana. And, he said, a small worm that attacks plant roots may work in conjunction with the fusarium to kill the plants.
“Most of the species [of fusarium] are found as epiphtyes — that is, they live on the surface but don’t cause disease,” Elmer said. When the plant is stressed, the fungus turns deadly.
“My hypothesis is there’s an initial stressor — probably rising sea level.”
The most intriguing theory behind the fusarium is that it arrived here after being carried across the Atlantic Ocean on huge dust storms stirred up by ongoing drought in northern Africa.
Scientists estimate that hundreds of millions of tons of dust from Africa may reach the Southeastern U.S., Caribbean and Amazon basin each year. The dust can carry bacteria and other pathogens — including fusarium — on a five- to seven-day journey across the ocean. The dust has been tied to respiratory problems in Florida and the Caribbean, the declining health of coral reefs and red tide blooms.
The drought itself appears related to a well-known climate fluctuation, the North Atlantic Oscillation. It is worth considering that one of the predicted consequences of warming temperatures is greater surface evaporation and more frequent drought.
Elmer is trying to get a sample of some of the African dust to see if he can isolate fusarium and compare its DNA with the local strain.
“If I found the same thing in that dust, then I would be further along in believing that that’s how this pathogen got here,” he said. “Even if it’s identical genetically, it doesn’t prove it. Dust clouds may have been coming here for thousands of years.”
Whatever the marshes’ problems, the rising sea level spells bad news for the saltmarsh sharp-tailed sparrow. The secretive brown bird only breeds in high marsh grass from Maine to North Carolina. Twice a month, the areas where it builds nests are flooded by the “spring” tides — the especially high water at the full and new moons, when the sun, Earth and moon are in alignment.
Their first nests are often washed away. They rebuild right away, putting them in synch with the spring tides. Barring unusually high tides or heavy rains, they have about 24 days to lay eggs, raise their young and get them out of the nest before the next flood.
Chris Elphick, a conservation biologist at the University of Connecticut, studies the sparrows in places like Hammonasset, the East River in Guilford and the Hammock River in Clinton. The sparrow is not endangered yet, but sooner or later it probably will be, he said.
It’s not obvious what difference it will make if the sparrow dies out. “But we’ll be losing yet another species, or have another species declining, and that’s going on all the time around us,” Elphick said. “We pay attention when the last one of something goes.”
At Hammonasset Beach State Park and elsewhere around Long Island Sound, efforts are underway to restore marshes that had been filled or drained years ago. One might ask if there is any point to this activity now, or even of studying marshes that, if climate predictions are on target, almost certainly will disappear.
Roman Zajac seems of two minds on the subject. Back in his UNH lab, he and graduate student Leah Pabst use their computers to compare elevation maps to their GPS data and an aerial photo of Banca marsh taken in 2004.
“If sea level rise is the driver, there’s not much we can do besides going Dutch,” Zajac joked, referring to the Netherlands’ famous dikes that hold back the sea.
On the other hand, he said, their work can at least help us understand how the change is affecting the area’s ecology.
“It may help predict what marshes are more susceptible than others [to dieback],” he said. “It can be a good planning tool for marsh protection and shoreline protection.”
Pabst is writing her master’s thesis this summer on fish populations in the Quinnipiac River marshes, where there is plenty of evidence of dieback. She has spent many hours paddling and pushing a canoe up shallow tidal creeks to gather fish samples, slogging through sticky mud that can suck your boots down like quicksand.
Pabst is frustrated by what she sees.
“You try to be objective as a scientist,” she said. “It’s very difficult to do that in the climate we have today. It’s becoming an ethical and moral issue.”
“Unfortunately people are going to have to deal with [global warming] on a personal level — and that’s when it’s going to be a problem,” she said. “Americans like what they want and when they want it. They don’t want to bend over and do anything because they have it done for them. …
“People I work with who are my age, we’re pissed off. We don’t want to inherit this problem, and have our kids inherit it.”

Some related websites: wetland.neers.org — New England Estuarine Research Society www.epa.gov/owow/oceans/nepccr/index.html — EPA: National Estuary Program Coastal Condition Report, June 2007 www.longislandsoundstudy.net — The Long Island Sound Study www.aswm.org/science/dieback/dieback.htm –Association ofStateWetlandManagersearthobservatory.nasa.gov/Newsroom/NasaNews/2001/200106144886.html – NASA

Copyright © 2007, THE HARTFORD COURANT. Unauthorized reproduction or Web posting prohibited.

Update, May 2, 2014: Two newly published studies by a team of Brown University researchers provide ample new evidence that the reason coastal saltmarshes are dying from Long Island to Cape Cod is that hungry crabs, left unchecked by a lack of predators, are eating the cordgrass. Read more here.

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