Salt Marshes Stink!

marsh

This week’s science adventure took me to a salt marsh in Barrington, Rhode island, with scientists Kenny, Tom, and Scott. With a wheelbarrow, numerous steel rods, two plastic step-stools, a plank of wood, several bags of quick-drying concrete, food and water for a hard day’s work, and sophisticated equipment that talks to satellites, we trudged through spongy, oozing, pungent coastal marsh.

And boots. Don’t forget tall, waterproof boots—-or waders if you’re lucky—-if you venture into the marsh. A salt marsh floods with the tides, and it’s a boggy, stinky, and treacherous place.

mud

Careful where you step, or the marsh may suddenly swallow a limb.

It’s hard to describe the stench of the marsh’s thick black mud. Mix rotten eggs, worn and moldy socks, and a briny tang, and you might be getting close. It’s an odor I’ve come to love, living in coastal Rhode Island, reminding me of happy days in my kayak, floating by spindly spider and fighting fiddler crabs, mussels, oysters, tiny fish called mummichogs, and graceful great blue herons and egrets. You can feel the abundance of life around you.

fiddler

Fiddler crab

Wetlands are areas of high productivity, meaning uncountable plants are breathing, growing, and reproducing, using sunlight to turn carbon dioxide and water into food for themselves and other organisms.

goose

Both migrating and resident Canada geese visit the salt marsh.

Macro-algae, various marsh grasses, and islands of shrubs, juniper trees, and other plants grow here. As Tom tells me, “Wetlands are now thought to be as productive as rain forests.”

It’s thrilling to be surrounded by one of the planet’s greatest carbon sinks. (A carbon sink is an area where productivity is high. Here masses of carbon dioxide—a major greenhouse gas—are taken up by plants.) Salt marshes, like other areas of high productivity such as rain forests and the Southern Ocean, are vital for mitigating global warming and climate change.

Today, Kenny and Tom are installing SETs—“surface elevation tables.” It’s an appropriate acronym for points set in concrete. Scott then uses sophisticated equipment to determine the elevation of each.

“I’m tying the SET into the National Spatial Reference System,” says Scott. “Water levels are rising, and salt marshes need to rise at the same pace. Otherwise they will flood and turn into mudflats—where vegetation can no longer grow.”

They will return to this marsh—and others like it—again and again over the years, measuring how its elevation and health change over time. Will they grow and rise? Will growth keep up with rising sea levels? Or will they sink, die, and regress?

stake

Scott and Kenny work together to pound a long metal pole deep into the spongy ground.

Tom, who has been mixing concrete to hold the stake in place, stands and stretches. This is hard physical work, and we are tired, wet, and filthy. He gazes out over the waving marsh grasses. “I grew up by the salt marsh. We could play football on the marsh in those days.”

kt

Tom concretes the stake into place, while Kenny spreads powdered rock called feldspar.

“You couldn’t do that now,” Kenny says matter-of-factly. We look down at the soggy peat below us. It ripples beneath us with each strike of the post hammer. “Especially here—this marsh is so degraded.”

“They didn’t used to stink as bad,” says Tom. “A lot of the stinkiness is due to the fact that they are now drowning in place due to sea level rise, sadly.”

Now Kenny is shaking out white powdery feldspar over two sections of the plot. “The feldspar is for what’s called a marker horizon,” he says. “As organic and inorganic material gets deposited on it over time, we can later take a small core and measure how much has accumulated over the feldspar over time, divide by time, and you get a surface accretion rate.”

“Why should we care about marshes?” I ask as they all take a breather. Kenny and Tom reel off a list of reasons.

Salt Marsh Facts:

  • Salt marshes grow on coasts and in estuaries the world over. In the US, they can be found on every coast.
  • Salt marshes stink due to the gases given off by decomposing organic matter.
  • The soil is composed of spongy peat (decomposing plant matter) and thick mud.
  • The marsh is frequently flooded, then drained, by salty tidal water.
  • Salt marshes provide a habitat—including food, shelter, and a safe place for juveniles—for over 75% of the fish and selfish humans enjoy.
  • Humans love wetlands and estuaries too for fishing and shell-fishing, boating, paddling, birding, and more.
  • Salt marshes protect shorelines from erosion and buffer wave action, especially during storms.
  • They trap sediment, which also helps protect the estuary.
  • They absorb rainwater and reduce coastal flooding.
  • They filter water and absorb excess nutrients (e.g., from fertilizers), thereby keeping beaches and waterways cleaner.

Salt marshes might stink, but what’s not to love about them? They are essential for our economy, culture, and environment.

marsh

We love the salt marsh!

You can see an interview with Kenny in this piece by the Providence Journal.

Kenneth Raposa is a salt marsh ecologist with The Narragansett Bay National Estuarine Reserve, Tom Kutcher is a wetland scientist with Rhode Island Natural History Survey, and Scott Rasmussen is an environmental scientist with the Environmental Data Center at the University of Rhode Island. This project is funded through the RI Coastal Resources Management Council (CRMC) to establish two additional long-term salt marsh monitoring sites to complement the existing few sites. The goal is to build a strong network of long-term sites around all coastal RI to gain a better understanding of what is happening to salt marshes throughout the state.

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