Bates College professor Bev Johnson and her students conduct climate change research in Sprague Marsh at the Bates-Morse Mountain Conservation area in Phippsburg. Brianna Soukup/Staff Photographer

Bates College professor Bev Johnson and her students conduct climate change research in Sprague Marsh at the Bates-Morse Mountain Conservation area in Phippsburg. Brianna Soukup/Staff Photographer

Recent Bates College graduate Cailene Gunn loves salt marshes. She just moved across country to the Olympic Peninsula in Washington for them. OK, for a job involving salt marshes – with the Pacific Northwest National Laboratory, one of the U.S. Department of Energy’s national laboratories – but still.

The Granby, Connecticut native fell hard for the coastal grasslands while studying at the Bates-Morse Mountain Conservation Area, 600 acres of coastal uplands and salt marsh in Phippsburg. The beachgoing public knows the marsh primarily as the place they walk past – swatting mosquitos – on the way to pristine Seawall Beach. But beyond preservation and limited recreation (the beach is accessible only by foot) the conservation area’s primary function is to serve as a research and educational laboratory for both Bates students and professors.

Those educational experiences can lead to jobs like the one Gunn just landed. She believes the fact that she was so enthusiastic (“chatty”) about her senior thesis on a salt marsh in Harpswell, damaged by human impact but now in recovery, is what prompted the lab to create a research associate position for her.

Gunn lived at the conservation area for a summer, at Bates’ nearby property Shortridge, and she and other classmates rave about having had that opportunity.

“I have got to say it was the best,” Gunn said. She’d put in eight hours of lab work, but the perks including kayaking, hiking and sunbathing. “We just have access to this beautiful beach and get to play outside all the time.” Just as valuable was being part of the greater coastal community in Phippsburg, she added. “They care about what is happening to the coast, and that is really special.”

The work Gunn did was an off-shoot of her geochemistry professor Bev Johnson’s research into the long sedimentary history of the Sprague salt marsh at Bates-Morse Mt., a project that has helped set international standards for blue carbon.



If you’ve never heard that term before, don’t worry, Gunn arrived at Bates knowing nothing about blue carbon either.

Here’s a primer. Our carbon output, i.e. emissions, is a key contributor to climate change. While President Ronald Reagan infamously blamed trees for pollution, the amount of carbon dioxide, or CO2, they absorb is a net positive, environmentally speaking; they offset emissions from our factories, cars and other components of the developed world. What scientists have dubbed “green carbon” is the carbon absorbed by natural, biological processes. It can’t stop climate change, but it could slow it.

In the past decade, scientists subdivided that green carbon descriptor, recognizing the carbon captured in the oceans as “blue carbon.” Even more recently, they created an entirely separate category for the coastal blue carbon systems, that is, mangroves, salt marshes and seagrass meadows. Here’s the part that relates to Gunn’s work as a student at Bates, as well as Johnson’s work as a member of the international Blue Carbon Scientific Working Group. The part of the ocean habitat that is vegetated, whether it be with mangroves, seagrasses or salt marshes, is astonishingly efficient at storing carbon. Such areas cover less than half a percent of the seabed, but scientists say they account for as much as 71 percent of all carbon storage in ocean sediments. Better than trees.

Beverly Johnson looks at sediment changes in a core sample at the Sprague River Marsh in the Bates-Morse Mountain Conservation area. Brianna Soukup/Staff Photographer

Beverly Johnson looks at sediment changes in a core sample at the Sprague River Marsh in the Bates-Morse Mountain Conservation area. Brianna Soukup/Staff Photographer

“Coastal blue carbon systems sequester roughly 15 times more carbon per unit area than the upland forests do,” Johnson said. “They are really good at it.” And because those sediments are free of oxygen, the carbon can remain stored for thousands of years if left undisturbed.

In other words, salt marshes, just by doing their thing, that is, growing reedy grass in peat that gets soaked by the ocean twice a day, are diligently capturing and retaining the carbon that we don’t want in the atmosphere. In Maine alone, approximately 73,000 tons of CO2 are sequestered in salt marshes annually.


Johnson likes to do the math in relatable numbers: that’s equivalent to the amount of carbon emissions produced by about 15,000 cars every year. Sprague Marsh alone sequesters approximately 900 tons of CO2 annually, or what’s produced by 200 passenger cars every year. Johnson knows that relatively speaking that’s not a big number. But, she says, “every little bit helps,” and that’s why these ecosystems are now part of the international carbon accounting system.

Salt marshes were already known to offer protection from rising seas, to prevent erosion, take up pollutants and provide nursery habitat for commercially important fisheries, as well as shorebirds. Now they’ve been shown not merely to help with the impacts of climate change, but to slow its pace. In theory anyway.

So Gunn loves those mucky, typically fairly smelly marshes for a reason: They’re our allies, albeit unintentionally, in fighting climate change.

The cloud on this sunny discovery is that they’re under siege from development.


Sprague Marsh and the surrounding land does not technically belong to Bates; it’s owned by a nonprofit corporation comprising the St. John family (the land’s original owners) and the general public. The Nature Conservancy holds conservation easements on the property while Bates, which has a 50-year lease, manages the area. Laura Sewall, whose teaching background is in eco-psychology, is the director of both the Bates-Morse Mountain Conservation Area and the nearby Shortridge Coastal Center, a residential property where lucky students like Gunn might get to spend a summer while doing research on the land. It’s also her job to help facilitate research on the site.


Bev Johnson, center, with her student Kelsey Chenoweth, left, and Philip Dostie, assistant instructor in environmental geochemistry, at Sprague Marsh. Brianna Soukup/Staff Photographer

Bev Johnson, center, with her student Kelsey Chenoweth, left, and Philip Dostie, assistant instructor in environmental geochemistry, at Sprague Marsh. Brianna Soukup/Staff Photographer

Sewall has been at Bates since 2008, but her roots in the Phippsburg area go much deeper; her family has long been part of the nearby Small Point Association, which owns the beach so many hikers (about 20,000) access during the summer months. She’s always known the property was unique, but research by Bates students and professors has only heightened her sense of its importance.

“It is the largest undeveloped barrier beach in the state,” Sewall said. Barrier meaning that the dunes on the beach protect the marsh beyond it. “And we are very proud of the marshes because they provide so much ecosystem service, blue carbon being just the latest.”

The Maine Geological Service, a part of the state’s Department of Agriculture, Conservation & Forestry, surveys the beach once a year, and according to the survey’s marine geologist Stephen Dickson, uses it, along with Reid State Park, as a bellwether for the whole state’s coastline. “What happens there is all occurring because of the forces of nature rather than the influences of people,” Dickson said. As a control, it helps them determine whether human development is causing problems in other areas. “But if everybody is eroding, including Seawall and Reid State, then the problem is much bigger.”

The information packed into the sediments of Sprague Marsh dates back several thousand years, he said. “It’s a wonderful natural laboratory that is really rare in Maine.”


Bates is by no means the only college with a research facility right on the coast. Darling Marine Center in Walpole is the University of Maine’s marine laboratory. The College of the Atlantic has access to not one but two islands, the 220-acre Alice Eno Field Research Station and, 25 miles off shore, the Edward McC. Blair Marine Research Station. Bowdoin students work at both the college’s Coastal Studies Center on Orr’s Island in Harpswell and the Bowdoin Scientific Station on Kent Island in New Brunswick.


All these institutions are part of a new consortium of 12, the Northeastern Coastal Stations Alliance, which was founded last year to share and coordinate research in the Gulf of Maine. Sewall helped organize the consortium with grant support from the National Science Foundation. Bates-Morse Mountain is a member.

“I see it as a field station in the rough,” Sewall said. “We are developing a greater body of research that comes from that specific place.”

That includes the salt marsh work led by Johnson, as well as long-term beach research done by professor Mike Retelle and his students, particularly on changing sea levels due to melting glaciers. One of his students wrote her thesis on how rising sea levels will affect Phippsburg. The sexy outtake? It’s going to be an archipelago. Beyond that, studying historical sea level increases allows us to shed light on the future. And, this record shows, sometimes sea level changes have happened in more drastic steps, rather than steady increments.

Bates College professor Beverly Johnson works with a couple students studying climate change at the Sprague Marsh. Brianna Soukup/Staff Photographer

Bates College professor Beverly Johnson works with a couple students studying climate change at the Sprague Marsh. Brianna Soukup/Staff Photographer

“Looking at the past can actually tell us, don’t expect things to happen slowly,” Retelle said.

Biology professor Brett Huggett works in the upland forest with his students (one of whom, Isobel Curtis, spent the summer at Bates-Morse Mountain surveying over 250 hemlocks looking, and unfortunately, finding, for signs of hemlock woolly adelgid, an invasive insect from Asia making inroads on Maine’s coastal communities, where warming temperatures are allowing it to thrive).

Comparing research from locations up and down the coast, where there are boots on the ground observing changes over time, is, Sewall said, “believed to be some of the best ways at looking at our bigger environmental issues, like ocean acidification.”


And the growing peril to powerful parts of the ecosystem such as salt marshes. A report on blue carbon by the United Nations Environment Programme says worldwide, mangroves, salt marshes and seagrasses are disappearing “faster than anything on land” and may be entirely gone in a matter of decades.

Approximately 50 percent of the world’s salt marshes and mangroves have already been destroyed, Johnson said. Current rates of loss are between 1 and 2 percent per year, and the losses are greatest in developing nations. Some of the biggest culprits are the creation of shrimp and fish aquaculture ponds, run-off from agriculture, and human expansion into coastal areas.

In Maine, salt marshes are abundant (mangroves are not part of our ecosystem; you’d see them in warmer areas such as Louisiana) but they’re typically compromised in some way, whether because someone built a road over them or plugged them up for agricultural reasons.

“It turns out about 95 percent of salt marshes in the United States have been altered,” Johnson said.


Professor Johnson’s students, some of whom came to Bates without a clue as to what they wanted to study, sing her praises. But it might help that their professor happens to have a very appealing classroom; there are few more spectacular places in midcoast Maine than Sprague Marsh.


“I was definitely very interested in the sciences,” said senior Danny Stames, one of Johnson’s thesis students. “That was my thing in high school. But I wasn’t entirely sure what I’d major in. But Bev in particular just has this wonderful ability to take these science-related questions and break them down for the layperson.” That influenced his decision, but so did Bates-Morse Mountain. “Just the fact that you can be outside? Being able to work in a salt marsh and get credit for it? That’s so great.”

Before Johnson came to Bates, she studied sedimentary history in Australia, where she said her research was centered around the continent’s record of fires. (She found that while Australia was always seasonally adapted to fire, those fires increased dramatically as soon as humans arrived, some 50,000 years ago). At Sprague, she uses stable isotope geochemistry to learn the history of the marsh – and how it has moved over time – by taking sediment cores throughout the marsh.

When the Blue Carbon Scientific Working Group was founded in 2011, one of its goals was to establish standards for quantifying and monitoring coastal carbon. Using her work in Sprague Marsh, Johnson helped write the manual for measuring carbon stocks – and fluxes – in blue carbon ecosystems. The scenic marsh in Phippsburg, then, has had ramifications worldwide.

Despite its relative lack of development, Sprague Marsh was used for haying in Maine’s early days, when forests covered so much of the land that the grasses from the salt marsh were harvested for animal feed. Farmers would “ditch” the marsh, creating a cut perpendicular to the tidal channel. “So that it is drier and you can get out on it and harvest the hay,” Johnson explained.

That practice continued through the 1960s, Johnson said.

Beverly Johnson works with her student, Kelsey Chenoweth. Brianna Soukup/Staff Photographer

Beverly Johnson works with her student, Kelsey Chenoweth. Brianna Soukup/Staff Photographer

Ditching decreases the salinity of the marsh, and if access to the tide is further limited (say, by a culvert), that leads to an unhealthy marsh, invaded by freshwater plant species such as typha (cattails) and steadily rotting. Instead of functioning as efficient carbon sinks, these unhealthy marshes start giving off methane gases (another greenhouse gas, even worse for the atmosphere than carbon emissions).


At Sprague Marsh, a well-intentioned but ill-fated project by U.S. Fish and Wildlife to provide more habitat for offshore fish breeding led to plugging up a previously ditched part of the marsh, enabling fresh water to pool up behind a now 15-foot earthen dam and creating considerable methane emissions. (As well as excellent mosquito habitat. If you like mosquitoes.)

“What ends up happening (is) you don’t get any exchange with the tides anymore,” Johnson said. “So you get a really wet marsh, leading to decomposition of the peat and release of the CO2.”

But the fish, and the shorebirds that feed on them, did rebound, she said. It presents a dilemma.

“We have to make choices about how we use these landscapes,” Johnson said. “If we value shorebirds and fish for shorebirds more than anything else, it makes sense to put in these plugs, but then you miss out on what these ecosystem services can provide. The interesting question is, which ecosystem service do you value more? I personally don’t know what the answer is. The carbon is pretty important.”

The Blue Carbon Initiative (the overseeing body of the scientific group) estimates that at least 67 percent of the world’s mangroves have already been lost. For seagrass meadows, that loss is 29 percent. At least 35 percent of the world’s salt marshes are already gone.



Gunn started her work in Sprague Marsh taking core samples with Johnson, and became intrigued by the methane emission issue. She trained Stames and Kelsey Chenoweth, both of whom are working on thesis projects in area salt marshes.

Gunn focused her thesis work on Long Marsh on Long Reach Road in Harpswell. A simple restoration project there in 2014 swapped in a 14-foot culvert for the 3-foot one that had restricted the tide to part of the marsh. As Gunn took samples on the marsh, she saw a decrease in methane emissions in less than 16 months and a 92 percent decrease in the typha that had invaded the marsh. Once again, the salt marsh could function as a carbon-sequestering body – blue carbon.

Gunn said over 90 percent of the salt marshes in Casco Bay are restricted by culverts. Does that mean we can help stave off climate change by replacing them with culverts that allow the tides to flow? That would be good, but Gunn thinks it would be a hard sell.

“Since the marshes in Maine are pretty small, the economic significance isn’t enough to really push other projects,” she said. But Washington state has some big marshes, and she hopes to use her Bates research on that larger playing field to help turn the tide for those salt marshes.

“They are so important for the health of the coastlines,” she said. “And taking care of them isn’t that hard.”

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