Fins surfaced in the tidal creek, drawing Matt Wright’s attention away from the boat in the growing dusk.
The 48-year-old Illinois resident was on his first tour of a salt marsh when dolphins appeared around the vessel, gently swimming through the estuary as shadows advanced across the tideland.
Brilliant green spartina grass stood in the marsh mud, contrasting sharply with the dark water. The red-orange sun sank lower on the horizon, refracting light through the tall grass.
It’s a peaceful image Wright still can’t get out of his head, months after seeing the spectacular landscape that day in June.
“People think that if you are looking for really beautiful scenery, you’ve got to go to the Rockies,’’ Wright said. “But being out there in the creek and having the sunset cruise with all the scenery -- and all the wildlife, was a very memorable experience.’’
Salt marshes like the one Wright visited are segments of the Carolinas and Georgia that many people find hard to forget. The briny wetlands provide food and shelter to marine life, fuel local economies, draw recreational anglers and commercial oystermen, and provide scenery that distinguishes them as unparalleled in the eastern United States.
But these expanses of grass, which cover 1 million acres from the Outer Banks to north Florida, face danger from the earth’s changing climate and rising seas. Higher ocean levels threaten to erode marsh banks and kill tidal grasses.
Some areas are already experiencing changes. Parts of the South Atlantic coast are sinking, tidally driven floods are increasing, marsh grasses are thinning, trees are dying and water is covering research equipment that used to stand in the grasses.
Changes in South Atlantic salt marshes are not as obvious as what’s occurring on the Gulf Coast, where thousands of acres of marine wetlands have eroded and entire islands have disappeared. But scientists in the Carolinas and Georgia are paying close attention as the warming earth causes the sea to expand and polar ice to melt.
Anywhere from 14 to 34% of the existing salt marshes along the South Atlantic could be lost by 2060 if seas continue to rise as expected, according to the National Oceanic and Atmospheric Administration’s Charleston office, which bases its estimate on a variety of factors, including a moderate increase in ocean levels.
Marshes near Wilmington, Charleston, Myrtle Beach and Savannah are among those facing threats.
Sea levels have risen about 3 millimeters annually, on average, in the past 100 years along much of the South Atlantic coast, but in the past 30 years, the rate of that rise has increased to about 5 millimeters annually, according to NOAA in Charleston..
In the past 10 years, the rise has approached 15 millimeters per year, federal scientists in Charleston said.
“These vast expanses of marshes we are accustomed to in the Southeast are going to disappear,’’ said University of South Carolina scientist Jim Morris, one of the nation’s leading experts on salt marshes.
The South Atlantic's Sea of Grass
The South Atlantic coast has some of the most extensive salt marsh systems in the country. The marshes cover about 1 million acres from North Carolina's Outer Banks to North Florida. Areas in pink on his map show approximate locations of salt marshes. Source: NOAA
“The scientist in me says that is the way it is. I can study this and not get emotional about it. But the other side of me is saddened.’’
Sea level rise threatens all types of salt marshes, but those most at risk are in areas of exploding growth, where virtually every parcel of oceanfront land has been developed and people have turned to tidelands behind the beaches as places to live and work.
Places where marshes were filled long ago to develop property are experiencing ever-worsening floods that, during full-moon tides, often send water into streets and yards.
Seawalls and bulkheads have been built to prevent marshes from eating away grassy lawns and parking lots near the water, but these structures are speeding up the loss of marshes.
In the Carolinas and Georgia, state regulators have approved at least 28,000 permits for docks, bulkheads and other development in tidelands during the past three decades, according to data provided to McClatchy by the three states. That, however, is only a snapshot of the permitted work because state agencies did not provide some of the data requested by McClatchy.
The powerful combination of marsh-side development and sea level rise increases chances that some of the region’s most visible tidelands will drown, scientists say.
Development prevents marshes from naturally moving inland, as the tidelands would under normal conditions. As a result, vulnerable marshes can shrink, eventually disappearing beneath the rising water.
Scientists and conservation groups are scrambling to learn more, while bracing for expected changes to salt marshes.
In southern Georgia, scientists are experimenting with a restoration project - piling dredged mud on an island - which they hope will help protect salt marshes before ocean levels rise too high and overwhelm the grasses.
Conservationists are in a race to protect undeveloped land along the Southeastern coast so marshes can move inland as seas rise. At the same time, researchers are advocating for stricter controls on development near tidal creeks and salt marshes.
But to slow the pace of rising seas, sharp reductions in greenhouse gases must be adopted, and that won’t stop sea level rise altogether, scientists say.
What’s at stake from sea level rise in the Southeast
What’s it all mean?
The Carolinas and Georgia have some of the most extensive stretches of salt marshes in the country. South Carolina and Georgia each have about 350,000 acres of salt marsh, while North Carolina has about 225,000 acres.
Coupled with North Florida, the 1 million acres of salt marsh rival the acreage of the land at Grand Canyon National Park. More than half of the country’s existing salt marshes are found on the South Atlantic and Gulf Coasts, according to a 2015 report headed by researchers at the University of North Carolina.
If salt marshes disappear, converting to open bays or mud flats, the multi-billion dollar tourism economies of the Carolinas and Georgia could take a hit.
So could the recreational and commercial fishing industries because marshes are rich with young fish and crabs that grow into the seafood people catch for sport and eat in restaurants.
Hurricanes and tropical weather, increasing threats to the coastal South, could have more devastating impacts if salt marsh grasses aren’t there to slow storm surges before water washes onto the mainland.
Wildlife people are used to seeing in marshes could leave or die.
The future of salt marshes is an economic concern for Lori Galloway, a North Carolina shrimper and seafood dealer, and Richard Mitchell, a South Carolina waterman. Both are heavily invested in the seafood business, their families working for generations in the ocean and marshes of the South Atlantic coast.
Both already are worried about pollution hurting water quality in the marshes. Mitchell recently learned that part of the area where he harvests oysters has been closed for the season because of bacteria contamination.
Still, oyster beds can be reopened if water quality improves.
Sea level rise is a sustained threat.
“The marsh is important for the ecosystem because shrimp, crabs and fish all feed in them,’’ said the 78-year-old Mitchell, who learned how to harvest oysters from his mother when he was a youngster on Hilton Head Island. Today, he collects oysters with help from his grandson.
“Something would be terribly wrong if all the marsh grass disappeared.’’
Galloway, who runs High Rider Seafood near Holden Beach and Oak Island, said she’s seen a surge in development along the southern North Carolina coast that threatens the marshes and waterways her business depends on.
“We’ve got too many golf courses and too many houses; they’re building docks straight out into the marshes,’’ the 51-year-old Galloway said. “You’ve got to have your marsh grasses if you want the sea life.’’
Salt marshes face threats, in large part, because carbon dioxide and other gases have heated the atmosphere, causing both air and ocean temperatures to increase.
Saltwater expands and rises when it is heated up. And melting ice at the poles is dumping more water into the sea.
Signs of change
On a bright day this past summer, Morris’ research assistant, Karen Sundberg, drove down a series of dirt roads to see how encroaching salt water had affected a big marsh near Georgetown, S.C., about a half hour’s drive south of Myrtle Beach.
Dying cedar trees stood along Goat Island Road as she maneuvered the truck to the scrubby island in the marsh at North Inlet, a University of South Carolina research area.
Salt water had inundated the trees, causing them to stand ghostly white in the glaring mid-day sun.
Hurricanes have flooded the trees with ocean water in recent years, but the steady rise in sea levels likely played a bigger role in their deaths, said Sundberg and Erik Smith, a scientist who works with her at USC’s Baruch Marine Lab on North Inlet.
“Dead trees on the edge, that’s sea level rise,’’ Smith said. “Cedars are the last ones to go.’’
This graphic uses NOAA images of the Southeastern coast to show how sea level rise will impact salt marsh systems. The larger image will show the marsh system, in magenta, gradually being submerged under water as the sea level rises nearly four feet by 2100.
After parking the truck not far from the line of cedars, Sundberg walked on a long wooden platform to a spot well into the marsh, where research is underway.
Sundberg showed where areas of spartina grasses were not building up naturally as rapidly as areas where she had applied fertilizer.
Clumps of marsh grass stood taller and thicker where the plots had been fertilized when compared to the natural spartina grasses nearby. The marsh mud where plots had been fertilized also was higher.
The experiment was launched to see how the nitrogen and phosphorus in fertilizer affected the marsh in an array of ways, but it also showed researchers that the fertilizer made the marsh more robust.
It’s possible that could be one tool eventually to help marshes fight rapid sea level rise, but the idea of fertilizing marshes remains a point of fierce scientific debate.
Jumping into a skiff at the island’s boat landing, Sundberg cranked the motor and cruised down a tidal creek past muddy banks filled with oysters to a spot she and Morris said is among multiple places that show signs of rising seas at North Inlet.
A marsh monitoring device that once was surrounded by thick spartina grass now stands starkly in the mud, where it nearly disappears during high tide.
Overall, parts of the marsh at North Inlet are holding steady and keeping pace with rising water, but other parts are not, Smith and Morris said.
A key question now is whether the rise in sea levels will have more of an effect on the marsh system than sea level rise has had in the past.
“I can’t imagine the middle of North Inlet is not going to be open water by 2100,’’ Smith said.
Sinking and thinning in NC
Masonboro Island, N.C., is another spot where scientists have seen signs of change from rising seas.
In 2016, researchers reported that a section of the island’s salt marsh south of Wrightsville Beach was sinking by 1.9 millimeters per year, even as sea level was rising.
The subsidence has stopped, possibly because tropical storms blew sand into the marsh, said Brandon Puckett, a researcher involved in the Masonboro study.
But sea levels continue to rise. And that’s depleting grasses that hold the marsh at Masonboro Island together. Grass cover is thinner in some parts of the marsh, said Puckett, a research coordinator with the N.C. National Estuarine Research Reserve system.
“The thinning part has a lot to do with sea level rise and inundation,’’ Puckett said
Like at North Inlet in South Carolina, measuring gauges established in marshes around Beaufort, N.C., also are standing in open water, said Puckett and Carolyn Currin, a salt marsh researcher who recently retired from the National Oceanic and Atmospheric Administration’s Beaufort, N.C., lab.
Regionwide, researchers with the U.S. Fish and Wildlife Service say they’ve found evidence that some undeveloped salt marshes are losing ground to the swelling sea.
So far, “salt marshes are not quite keeping up with sea level rise,’’ service researcher Michelle Moorman said during a seminar in September. The service has been monitoring 21 federal wildlife refuges on the South Atlantic coast since 2012.
Scientists from the U.S. Geological Survey, universities in the region and NASA also have raised concerns about the future of salt marshes in parts of the Carolinas and Georgia, particularly those that are heavily developed.
Chester Jackson, a researcher at Georgia Southern University, said he has found chunks of the South Carolina coast are washing away. Erosion is a natural phenomenon that should be expected, but it is an increasing concern because sea levels are rising at an ever-increasing rate, he said. The question is whether the rise in sea level will be so great that it will worsen erosion, he said.
A study he conducted in 2017 found about 57% of the South Carolina coast has eroded since the 1800s. Jackson has made similar findings in Georgia.
Jackson said he’s pessimistic about the future of salt marshes in the region, most notably because of the developed areas that are blocking the marshes’ ability to expand onto new ground as the sea swells. But any marsh that can’t build up enough sediment to outpace sea rise is in trouble, he said.
Spartina grasses, the dominant species in Southeastern tidelands, are important because they trap sediment that rolls through on the tide. But if the sediment supply is inadequate and the sea rises too high, the marsh won’t build up and the grasses will drown.
“When the sea level rises faster than the marsh can keep up, we anticipate more erosion over time,’’ Jackson said. “That is the critical point.’’
Subsidence, or the sinking of land, is a bigger deal on the Gulf Coast, where land levels are lowering and sea levels are rising faster than on the South Atlantic. But there are spots on the South Atlantic where the land is sinking, including areas around Charleston, Georgetown and Savannah, researchers say.
“I tell my students the recipe for disaster is when you have a shoreline, the majority of which is eroding, and you’ve got subsidence going on at the same time,’’ Jackson said. “What that is doing is showing you geologically the area cannot sustain itself.’’
Some scientific research has painted a more optimistic future for salt marshes as seas rise.
A 2016 study that involved researchers from the Virginia Institute of Marine Science indicated that marshes actually build up faster the more they are flooded. The study examined 179 marshes in North America and Europe.
“My goal in 2016 was to provide a sort of reality check, that while we know marshes are in fact vulnerable, marshes also are highly adaptable,’’ said Matt Kirwan, an institute researcher who was involved in the study. “Sea level has been rising for 20,000 years and marshes in most places have survived that sea level rise.’’
On the Georgia coast, salt marshes could be lost over the long-run, but the short-term forecast is better, said Clark Alexander, director of the Skidaway Institute of Oceanography in Savannah.
While the amount of sediment needed to build up Georgia marshes is not keeping pace with sea level rise, the marshes already stand high enough to withstand major losses over the next 80 years, he said.
Even so, Kirwan said he’s become more concerned in the past five years about the ability of some marshes to build up sediment so they can survive.
Threats enhanced by development
The struggle of salt marshes to cope with sea level rise is an issue in many places like North Inlet and Masonboro Island, protected natural areas with extensive tidelands.
But the threat that sea level rise will drown salt marshes is greater in developed areas.
Salt marshes near Wilmington, N.C. and the beaches south of there - Charleston, North Myrtle Beach, Hilton Head Island, and Murrells Inlet, S.C., and Tybee Island and St. Simons Island, Ga. - are among those developed areas.
Bulkheads and other barriers
When tidal salt marshes are threatened by a rising sea level and erosion, they try to migrate upland. But many property owners use bulkheads and other barriers to protect waterfront property from erosion, and these have walled off tidal marshes all along the Southeastern coast. An alternative to that is what is known as a living shoreline. The use of materials such as oyster shells, native marsh grasses, wood, limestone, rip rap, as well as construction setbacks and slopes, and plantings of marsh grass help limit erosion and protect the marshes.
They are ringed by houses, bulkheads, docks and businesses - and when seas rise in places like that, marshes are trapped.
In developed areas, bulkheads and buildings block the rising water as it seeks to spread onto nearby land. With the marsh continuing to erode and development in the way, the tideland becomes more narrow until it disappears.
Nate Herold, a researcher with NOAA in Charleston, said multiple developed areas of the South Atlantic coast could have a hard time as ocean levels swell.
Spots around Charleston, Murrells Inlet, Pawleys Island, Hilton Head Island and Wilmington are among the South Atlantic marshes that are vulnerable in the face of rising sea levels, according to Herold’s research.
Using tide gauge data and intermediate sea-level rise projections, Herold estimates that North Carolina could lose up to three-quarters of its existing salt marshes by 2100 if sea levels rise by four feet, a projected increase used by many scientists studying climate change. By 2060, the state could lose 34% of its existing salt wetlands, the analysis found.
South Carolina could lose 46% of its existing marshes by the end of the century and 23% by 2060. Georgia faces the loss of 25% of its existing wetlands by 2100 and 14% by 2060, Herold’s calculations show.
Some of those existing marshes will move to other areas, such as up freshwater rivers. But the ones people know will change, Herold and others say.
“None of that surprises me,’’ USC’s Smith said, noting that the losses of existing wetlands could vary, based on other factors.
A Duke University graduate student, in a 2018 study now undergoing peer review for publication in a scientific journal, found that marshes surrounded by bulkheads are more likely to be lost than wetlands without bulkheads.
Samantha Burdick’s study looked at marshes in the Beaufort, N.C., area, comparing aerial imagery from the early 1980s to 2013. All told, 85 of 89 areas with bulkheads experienced a loss of marsh during that time, according to the report she put together in collaboration with NOAA’s Currin..
The N.C. Coastal Resources Advisory Council found the report interesting enough to discuss during a 2018 meeting, noting that Burdick’s research suggests “bulkheads have a significant effect on marsh loss through erosion and prevention of upland migration.’’
That’s an important finding since bulkheads have been commonly used to hold back water so that property along salt marshes doesn’t erode, even though Burdick’s study said they don’t actually perform as well during major storms as many property owners think.
Another report had similar conclusions. Bulkheads were among the main reasons wetlands were damaged in North Carolina’s 20 coastal counties, according to a 2021 N.C. Department of Environmental Quality habitat protection plan.
How salt marshes survive
When salt marshes are threatened by sea level rise, they have two survival strategies.
One is by increasing their elevation by trapping sediment or using below-ground biomass.
Another way is to move upland as sea level rises and salt water moves inland. The problem comes when bulkheads and other hard surfaces get in the way.
Records obtained by McClatchy newspapers identified some 5,000 approvals by state regulators for bulkheads on the Georgia-Carolina coast, with about 3,300 of those in North Carolina.
The amount of bulkheads, however, is likely far higher because North Carolina only provided data on bulkhead approvals since 2009.
South Carolina’s environmental agency gave McClatchy the Georgia Southern University study that Jackson conducted. It identified about 1,000 bulkheads in South Carolina.
Georgia has under 700 bulkheads, regulators there said.
The 2021 North Carolina coastal habitat protection plan provided a bold prediction: It said the demand for bulkheads and other erosion control devices will likely rise.
More than 48,000 properties valued at $13 billion are expected to become regularly flooded by 2100 under conservative sea level rise estimates, according to the report by the N.C. Department of Environmental Quality.
“Increasing development on the coast is expected to bring increasing demand for shoreline stabilization,’’ the report said.
Once reviled, now revered
Salt marshes for decades were underappreciated, even reviled, along the South Atlantic coast. Many people saw them as wastelands that inhibited development and provided habitat for mosquitoes.
Sea level rise threatens salt marshes
South Atlantic salt marshes most threatened by rising sea levels are on the southern North Carolina coast, the Murrells Inlet and Charleston areas of South Carolina, and Jacksonville, Fla., according to resiliency maps from the National Oceanic and Atmospheric Administration. Threats also exist in the Hilton Head Island-Savannah area. Areas in red and orange on this map show spots where marshes are least resilient to sea level rise. Areas in green are most resilient. Source: NOAA
Nationally, thousands of acres of marsh were filled to create farmland and make homesites near the water. Part of the most visible area of the historic Charleston peninsula is former marsh that was filled centuries ago.
“This practice continued into the 20th century, with little realization of the extent of impact filling salt marshes and tidal creeks has on natural drainage patterns, thus leaving the coastline in a heightened state of vulnerability, particularly during storm events,’’ according to the Guide to the Salt Marshes and Tidal Creeks of the Southeastern United States, a 2016 publication.
Places like Cherry Grove in South Carolina felt the impact of that attitude toward salt marshes as the Myrtle Beach area grew from a small regional vacation spot.
By the late 1960s, a private developer’s “massive dredge and fill operation’’ had turned parts of the salt marsh at Cherry Grove into high ground, according to S.C. Administrative Law Court records. Evidence presented during a 1999 trial, in which former U.S. Rep. John Jenrette sought unsuccessfully to build homes in part of the old marsh, showed that up to 20 blocks of vacation home sites were created by the original filling at Cherry Grove.
Harold Worley, a North Myrtle Beach businessman, said he remembers the operation as a youngster. A local contractor dug up marsh mud from the water, then piled it up on other parts of the soggy tideland to create the lots, Worley said. The developer also filled in a marshy channel that emptied into the sea at Cherry Grove, he said.
“It was marsh,’’ Worley said. “Anybody who tells you differently is lying like a dog.’’
Today, the Cherry Grove salt marsh is substantially smaller than than it was decades ago, and what’s left of the tideland is crowded by extensive development. The area routinely floods in the low spots that were filled in, said Worley, a former state representative who serves on the Horry County Council.
“In hindsight, it was probably a bad thing for the environment,’’ Worley said. “But it was a good thing for the economy.’’
As people learned more about marshes, they realized that the salt wetlands support an array of wildlife and fish, while slowing hurricane-driven storm surges. In the 1970s, the federal government began to limit filling of salt marshes, and state agencies followed suit, the 2016 salt marsh guide said.
People like Bob Perry are glad that happened.
Perry, a retired biologist with the S.C. Department of Natural Resources, spent part of his career working in the tidelands of Georgetown County.
Salt marshes always gave him a sense of renewal.
“It’s a refreshing, sort of clean place,’’ he said. “If you look across the big landscape, they make you feel good.”
In North Carolina, between the towering beach houses of Topsail Island and the rapidly developing mainland of Pender County sits a vast marsh system. Tucked into the middle of that is an oyster farm, spiky green grasses encircling a small cove where Cody and Rachel Faison have worked since July.
When the Faisons were searching for a new oyster lease, they looked at nearby marsh grasses to see if they liked a location. They were trying to find a place like this one, with sprawling fields of green grass, small fish flitting through the water and seabirds coasting above.
“It’s a grass that obviously looks alive and is supporting an ecosystem that is thriving,” Cody Faison said during an August trip to the lease site.
Sometimes, Faison said, he will be chest-deep in the water tending to the oysters when a school of red drum will pass by. Other times, he might see crabs, dolphins or sheepshead.
Working on the marsh, Faison said, “You just realize that you’re one small part of this big system that just seems to be doing incredible things around you.”
Tiny marsh fish sustains life
By most accounts, the loss of salt marsh, either from historic filling operations or rising sea levels, isn’t good for the coastal environment of the Carolinas and Georgia.
In these tidelands are fish like the mummichog, a tiny species that lives its entire life in the creeks and grasses.
The three-inch long fish may not sound important, but mummichogs are the food that many popular recreational and commercial species feed on, including red drum.
Red drum will scoot into the salt marsh and attack mummichogs, crabs, snails or other small marine creatures. Red drum are so aggressive their tails sometimes extend out of shallow water as they feed on tiny creatures below..
Other popular species, like flounder, feed on smaller marsh fish by ambushing them.
Flounder, often a staple of seafood platters at local restaurants, will wait in the tidal creeks adjacent to the flooded marsh grasses, then gobble small fish and crabs when the tide pushes their way.
If salt marshes dwindle, these species will have a harder time finding the food they thrive on. Already, some species, including flounder, are being watched carefully because of declining populations.
The blue crab, also a popular seafood along the Atlantic coast, is another species depending on salt marshes. After spawning upriver from salt marshes, female crabs swim back down river and release larvae.
The tiny crabs then float on the tides into salt marshes, where grasses provide protection as the crabs grow, Clemson University researcher Michael Childress said.
Dolphins like the ones vacationer Wright saw in June feed on mullet, squid and red drum, and sometimes chase fish onto the muddy marsh banks, coming partially out of the water and turning sideways on the banks to gobble the small fish.
The technique of catching fish on marsh banks, known as strand feeding, is important to some marsh dolphins, said Lauren Rust, a marine biologist and former federal fisheries official who founded the Lowcountry Marine Mammal Network.
“Strand feeding is a huge source of food for certain amounts of dolphins,’’ she said. “They rely on the marshes, the habitat, the structure.’’
An estimated 250 to 300 dolphins are known to live in tidal creeks in the Charleston area alone, she said.
Salt marshes are havens for oysters, like the shellfish Mitchell collects on the muddy banks at Hilton Head, as well as young shrimp.
Birds also flock to marshes. Among them are terns, ospreys, sandpipers and herons.
Money and storms
Salt marshes also help the economies of Georgia, South Carolina and North Carolina.
Tourism, fueled by visitors to the shores of the Carolinas and Georgia, has a multi-billion dollar economic impact on the region every year. And some of that is tied to salt marshes that are lined with restaurants, vacation homes and businesses that rent kayaks and boats.
Salt marshes at Calabash, N.C., and Murrells Inlet, S.C., have rows of seafood restaurants frequented by vacationers to nearby beaches, such as Sunset Beach just across the North Carolina line, and North Myrtle Beach.
Shem Creek at Mount Pleasant, just outside Charleston, has a cluster of seafood houses, as do areas around Brunswick, Ga.
To get an idea of how important salt marshes are to the economy, take Murrells Inlet. The small community, just south of Myrtle Beach in Georgetown County, S.C., is known as the “Seafood Capital’’ of South Carolina,
Murrells Inlet’s marsh-area restaurants have, in a single year generated more than $40 million in sales, according to a 2013 report from researchers at Coastal Carolina University.
Commercial fishing also depends on healthy salt marshes. In the three states, it is a more than $1.5 billion industry, according to federal statistics.
For all the economic impacts of tourism and fishing, one thing tidelands provide that is perhaps more important than anything is their ability to protect the coast from hurricanes and tropical storms.
Big storms are increasingly lashing the southern coastline. Marshes don’t stop the surges — mainland areas still get flooded — but these wetlands of thick grass slow down the water, experts say.
“They’re priceless, absolutely,” said Jill Andrews, coastal management chief at the Georgia Department of Natural Resources’ coastal division.
“When you see how little damage our community infrastructure and homes suffered, compared to other places where hurricanes have come up, it just feels like the benefit is there.’’
A 2021 scientific study found that coastal wetlands, including salt marshes, save more than 4,600 lives around the world each year and provide some $447 billion in storm protection.
The United States was among the top nations benefiting from coastal wetlands, which the report said save 469 lives annually and help avoid $200 billion in property damage.
Vanishing islands in Mississippi
The sea’s steady rise will continue to threaten the South Atlantic coast, but so far, nothing in the Carolinas and Georgia compares to what has occurred on marshes along the Gulf of Mexico.
There, entire islands have vanished under the water and thousands of acres of salt marsh have eroded away as river channels were diverted and oil and gas companies cut canals through the marshes.
As that was going on, sea level was rising.
From 1985 to 2010, Louisiana lost 16.57 square miles of wetlands a year, USGS geologist Brady Couvillion and colleagues found in a study of marshes. The state accounts for 80% of coastal wetlands loss in the United States, the survey says.
To put the marsh loss into perspective, the study by Couvillion and other scientists said, “If this loss were to occur at a constant rate, it would equate to Louisiana losing an area the size of one football field per hour.”
The Mississippi River built the bountiful marshes of South Louisiana with sediment that flowed from its mouth, but the river’s changing course and, later, levees erected to prevent flooding, deprived those same marshes of the sediment.
Oil production in the marshes contributed to erosion, as has sea level rise, sinking marshes as soils compact. The BP oil catastrophe in 2010 and devastating hurricanes have accelerated marsh loss along the gulf.
Much of the loss has occurred along the Louisiana coast, but substantial — and lesser known — problems have hit Mississippi, with rising seas chewing away at the marsh grasses and mud.
Mississippi has lost 10,000 acres of coastal marsh, around 16% of the total, in the past 60 years. That’s notable to fishermen, who ply the waters off Biloxi.
Wetlands have been filled for commercial and residential development, hurricanes have eroded the shoreline and rivers at both ends of the state have changed course, depriving the Mississippi Sound of sediment and hurting barrier islands.
“Islands have eroded away or shrunk,’’ said Chris Wells, executive director of the Mississippi Department of Environmental Quality. “Marsh complexes have shrunk in size. You can see over time the marsh literally eroding away.”
Is there a solution to sea level rise?
Sea level rise is a phenomenon that can’t be stopped cold anytime soon, but aggressive efforts to control carbon dioxide emissions from industries and automobiles could help slow it down, environmentalists, policy makers and many scientists say.
Beyond that, the Southeastern coast must look at ways to deal with the rising sea, said Todd Hopkins, a coastal resilience coordinator with the U.S. Fish and Wildlife Service.
One way to tackle sea level rise is to find land where the salty wetlands can move as the ocean overwhelms existing stretches of marsh, Hopkins and others say.
Other ways include building up marshes with dredged mud to make them stand taller and stronger as seas rise, or enacting tougher development rules to prevent construction in marshes.
Burdick, the former Duke graduate student who researched the impact of bulkheads in marshes, suggested requiring coastal development to be set back farther from marshes. She also favored using living shorelines — the use of natural materials such as oyster shells — to buffer property, instead of bulkheads.
Environmentalists say they are trying to acquire and preserve thousands of acres so that salt marshes will have room to move as rising seas advance. The Nature Conservancy, the Open Space Institute and Ducks Unlimited are among the groups seeking to strike deals.
“We’ve got to look at areas for marsh migration,’’ said Emily Purcell, an official with Ducks Unlimited in the Southeast. “All of us know, living in the Southeast, we’ve got tangible impacts from sea level rise squeezing coastal habitats.’’
The U.S. military, federal agencies and state natural resource departments announced an effort last spring to save salt marshes. Government agencies are developing a plan that would say how to preserve marshes.
The group is working with the non-profit Pew Charitable Trusts and it has drawn support from two dozen conservation groups. Pew has spent much of the year focusing on the need to save salt marshes.
Meanwhile, coastal regulators are watching the project at Jekyll Island, Ga., that seeks to determine if South Atlantic marshes can be built up and restored by pumping dredged mud onto them.
The good news is that some South Atlantic salt marshes will undoubtedly survive, and in fact, may grow more expansive because they have undeveloped land nearby where they can move naturally, as has been the cycle for thousands of years..
Much of Georgia’s coastal development, for instance, is clustered around the Savannah-Tybee Island area and around Jekyll and St. Simon’s islands, with the rest of the marshland undeveloped or lightly developed..
In South Carolina, miles of coastline between Myrtle Beach and Charleston, and Charleston and Hilton Head Island are protected as federal and state nature preserves. In North Carolina, vast stretches of the coast between Wilmington and Nags Head also are preserved.
Still, the loss of some existing salt marshes is inevitable, scientists say. The marshes people know today are in serious trouble, they say.
For Wright, the vacationer from Illinois who watched dolphins in the South Carolina tideland last summer, a concerted effort to protect salt marshes is worthwhile. The marsh he saw near Charleston is evidence of that, he said.
“One way to get people to care about this is if they can see these natural areas,’’ Wright said. “If someone sees that it is threatened, people will say let’s do something about it.’’
David Raynor, a database reporter with The News & Observer of Raleigh, N.C., contributed to this story.