Twelve years ago, my husband, Robert, and I began swimming the creeks and channels of the Great Marsh, the largest continuous stretch of salt marsh in New England. Its 25,000 acres of cordgrass marshes, barrier beaches and mudflats extend from Gloucester, Massachusetts to Seabrook, New Hampshire.
We made a pact with each other to swim every time we could. After a summer idyll of blue skies and marshes as lush as Kansas cornfields, we swam later into the fall, matching the dropped temperatures with thicker and thicker layers of neoprene. We took it for granted that we’d eventually hit a wall that would stop the swimming until the ocean warmed up again the following year. But as we swam in rain, darkness, and slushy water just above freezing, we discovered that walls are relative. Even a blizzard was navigable with the right gear.
Early on I began jotting down notes about the swimming. It was pretty basic stuff at first, but over time these notes evolved into an exploration of what happens when you immerse yourself in the same ecosystem over and over, through the daily changing of the tides and the yearly rotation of the seasons.
You certainly get to know the non-human inhabitants of a tidal estuary. Great blue herons, white egrets and banded kingfishers hunted for minnows in the same channels where we gathered mussels for our own dinner. Turkey vultures circled above us in Eben Creek. Once, floating downstream on a perfect July day, I was surrounded for a few minutes by a school of silvery minnows.
You also look more closely at the salt-marsh environment itself. Because marsh cordgrasses have adapted to handle immersion in salt water, they dominate the coastal marshes, converting enormous amounts of solar energy into grass. Though few creatures directly eat the grass, as it decomposes it becomes a vast, nutrient-rich environment for bacteria, algae, and fungi. These organisms, in turn, are food for snails, shrimp, oysters, clams, and hermit crabs—and so on up the food chain to muskrats and foxes and humans.
Even aside from its roles as feeder and protector of species, salt marshes are also unequaled as a kind of continental front bumper, a shock-absorbing barrier to storm surge. Break open a hunk of marsh wall and you’ll see dark, peaty stuff bound together with the pale-yellow gnarls and filaments of cordgrass roots, a structure that answers the question of how marsh walls can be so relatively lightweight and yet hold their shape so well, how spongey and soft can also be strong.
This peaty stuff is also a highly effective reservoir for carbon sequestration, helping to offset the negative impact of greenhouse gases.
As I continued exploring and writing, I came to understand that the daily tides and routines of a salt marsh are embedded within much longer tides and more consequential narrative arcs. The turkey vulture is shadowed by the 747. The Jet Skis that disturb the peace of perfect summer beach days are just noisier versions of our own daily commutes. When you swim a saltwater creek as the tide nears high, you have a visceral sense of what could happen if the tide just kept on rising.
The book is my small contribution to what will surely be an ongoing conversation and reckoning.
Special thanks to Gordon Harris, whose blog story, “Nuclear Ipswich,” very effectively made the point that history is not only about what happened, but also about what didn’t happen. Thanks also to Bellevue Literary Press for permission to use some adapted passages from the book.