Oysters | A Truly Miraculous Creature

Can oysters help New England’s coast survive climate change?

One Billion Oysters

The only place most of us ever see an oyster is on ice. It’s an expensive delicacy, a sensuous mouthful associated with the boudoir by way of the belly. If you live near the seacoast, your knowledge might extend to the names of a few favorite local oysters and the bodies of water in which they grow. In short, our only experience of the oyster, which has been around for 500 million years or so, is as food. Up and down the New England coast, however, in estuaries and harbors and university marine-science labs, researchers are beginning to see a far greater value in the American oyster, Crassostrea virginica, than as an amorous appetizer. Simply put, this creature’s intriguing and downright paradoxical characteristics make it a powerful candidate to help mitigate the effects of climate change while helping to rebuild our coastal ecosystems.

Let’s start with the intrigue. Oysters are remarkably good at filtering water, up to 50 gallons a day each when feeding. They consume plankton, algae, and organic matter, “cleansing” the water column of excess nutrients from various sources that can lead to damaging blooms, cloudy water, and lifeless bottoms. Their fixed life begins when they attach to a hard surface, preferably another oyster. Without this attachment, they perish. Unlike humans, whose growth rate is genetically predetermined, oysters grow only in the presence of sufficient food and save their energy by hibernating when the water turns too cold or otherwise unfit for their efficient operation.

Aquaculture farmers, benefiting from science and long experience, have become accomplished at hatching oysters and then growing them to market size by attaching them to microscopic bits of clamshell. In Maine, the Damariscotta River estuary nurtures seven million or so oysters. Rhode Island, New Hampshire, and Connecticut also grow out a further tens of millions for the insatiable consumer. One of the world’s prime oyster grounds is the more than nine square miles of Wellfleet Harbor in Massachusetts, home to the largest self-sustaining oyster population in New England. So far, so good: We have an abundant, renewable resource keeping our coastal waters clean and supporting watermen.

Time for the paradoxes. The American oyster is either male or female, depending on its age. The first year, most spawn as males, but turn female and release eggs generally by age 3. At the raw bar, you’re probably consuming immature oysters, as growers try to bring them to market by age 2. You’re also almost certainly eating a farmed oyster, for with the exception of Wellfleet, “wild” oysters don’t exist anywhere on our coasts in numbers sufficient to supply more than the locals foraging for their own tables. And the youngster you consume might be infected with either of two prevalent oyster diseases—Dermo and MSX— with increasing mortality as the oyster ages (neither disease affects humans). Occasionally, one strikes with breathtaking virulence, such as Rhode Island’s 1995 Dermo outbreak, which killed more than 98 percent of the state’s wild oysters in just four years.

We know from New England local histories and preserved shells that oysters can live for decades—and once grew to more than a foot in length on reefs so massive that they had to be dynamited when harbors and channels were built in the 18th and 19th centuries. But you won’t find many such specimens these days, or the reefs they grew on. Why? Because we’ve destroyed, built over, or polluted their coastal habitat, introduced diseases from other waters, and otherwise so altered the conditions for naturally sustaining populations that the only way they can survive now is with our help. Even then, we eat most of them before they’re sexually mature, further truncating the natural breeding cycle. Although there are a few scattered estuaries that have a “natural set”—a regularly occurring spawning cycle in the wild—it’s very likely that without long-term human intervention the oyster will disappear from New England’s waters almost entirely.

So are oysters a quasi-endangered species—or what’s for dinner? And why does it matter?

ONE OYSTER: URBAN COWBOY

Clad in rubber boots, Anamarija Frankić and I race across the six lanes of Morrissey Boulevard in Boston’s Dorchester neighborhood on a bright morning in June. We’re headed down a slope toward a polluted, choked-off basin called Patten’s Cove. Frankić, a marine biologist originally from Croatia, is slim and tanned from time outdoors, her short dark hair swinging with each energetic stride, talking rapidly about her research at UMass Boston, whose waterside science building we can see perhaps a mile away across the marshy, muddy landscape.

We’re looking for wild oysters. Working with students and the community and with funding from the Schmidt Family Foundation, Frankić has begun habitat restoration experiments, the success of which will largely depend on the survival of native oysters. But first, she needs me to imagine what once was.

“Oysters were the keystone species of the whole New England area,” she explains, “and we’ve lost 90 to 95 percent of them. Native American legends talk of walking across oyster reefs and flats to get from island to island, and we know from the middens [the piles of oyster shell, many 20 feet tall and once found all along the New England shore] that it was a super-abundant species. Today we have hardly any left—and we eat the toddlers!” To drive home how much we’ve lost, she quotes from the U.S. Oyster Census of 1880, which recounts that a single Wellfleet schooner in a fleet of many landed 1.5 million oysters in one day in 1877, representing 30 percent of what the area produced all last year.

We arrive at the cove’s edge. It’s low tide, and bottles and plastic trash litter the shore, which is mostly mud and rocks. “This area has the highest [level of] degraded water in the whole of Boston Harbor,” Frankić observes. “It’s almost like a sewer.” She walks out some way in ankle-deep water, bending to pluck an empty oyster shell from the muck. She waves it as her voice rises:“Historically, oyster reefs were spread along the New England coast like coral reefs, supporting our coastal system, its water quality and biodiversity, mitigating against erosion and stressors, like when you have too much nutrient or acidity changes. Oysters respond to that.”

Frankić speaks of oysters as almost a collective being: “Like they’re picking up signals from the environment and from each other, signals we can’t interpret with all our technology.”

For example, when nutrients such as nitrogen—from agricultural or sewer runoff or animal feces—flow into areas where human structures, including piers, wharves, yacht clubs, and sea walls, have blocked or diminished the tidal flows, they can stimulate plankton growth, which in turn can cause vast algae blooms that subsequently consume all the oxygen in the water.

In such “hypoxic events,” fish and other species perish, and eventually the algae die, too, falling to the bottom, where they smother what’s growing there to create the lifeless, oxygen-poor muck that lies below much of Boston Harbor.

Oysters, however, can sense this rise in available food and accelerate their growth. Present in sufficient numbers, they consume the excess nutrient, in the process incorporating nitrogen and phosphates into their shells and removing them from the environment. Frankić pauses, then bends to retrieve yet another open—dead—oyster. “Since we announced that there are oysters here, I feel like people are collecting them. It’s illegal to harvest anything except soft-shell clams all around here,” she says, her arm sweeping to embrace the whole harbor. She explains that immigrants to the area bring their food traditions, including foraging, with them, often not knowing how deadly red tide and other shellfish diseases can be: “Like so much, it’s all about education. We found cholera in some samples here. Not a good thing.”

When, however, a body of water is home to millions of oysters, Frankić explains, “they create a kind of microclimate that becomes not just micro but regional.” Oysters on the bottom build three-dimensional structure, not only providing the ideal place for newly spawned young to settle, but, as every fisherman knows, a place for fish and the things fish eat to congregate, mate, hunt, nest, and thrive. “When you think about why New England in the past had such amazing fish stocks,” Frankić notes, “it was because they were supported by estuaries that had salt marshes, oyster reefs, and eelgrass beds.”

Twenty minutes later, we’ve walked the whole stretch of cove, finding dozens of shells but not a single living oyster. “Last time I was here,” Frankić recalls, “I counted 156.” She stoops, frowns, and straightens abruptly. “Hey!” She points to a rock at the water’s edge, with an oyster about the size of a silver dollar attached to its side. I approach, and her fingers delicately trace the ridges of the shell. “That’s a thin shell, very young, very unhappy from the pollution. But alive!”

This project—part of a larger, international effort that Frankić leads called Green Harbors—began with the removal of 19 tons of debris and trash from this urban cove in 2013. This summer’s work is mapping, establishing baselines for various water-quality and biodiversity parameters, and further cleaning.

Frankić’s ultimate vision is of floating islands built of green materials, functioning, like the salt marsh that was once here, as silt traps so that the surrounding oyster beds she’ll plant can thrive and, in turn, rehabilitate the water. She foresees her students having a living laboratory to track how the oysters affect water quality, to record what plant and animal species come, and to witness the rebirth of an ecosystem.

ONE THOUSAND OYSTERS: THE OYSTER GARDEN

Dana Morse works for the University of Maine Sea Grant system as an educator and outreach resource for aquaculture programs. Always looking for ways to help residents learn more about their coast, he turned to an idea that had begun some years ago in the South and that has gradually spread from Oregon to Maine: oyster gardening.

It’s a warm June afternoon at the Darling Marine Center in midcoast Walpole, and I’m meeting Morse and this year’s class for an event unofficially called “Oyster In.” New gardeners will get their first spat (baby oysters grown out to fingernail size in a hatchery), which they must sew into fine-mesh plastic trays that they’ve made up as part of their winter education. It can take up to three years for the oysters to reach edible size; members of previous classes will move their juveniles, which have overwintered here in deep water, to larger mesh trays before all move to prime summer feeding grounds: raised steel racks planted firmly in the mud of Great Salt Bay.

We walk the length of a long dock dotted with small groups of oyster gardeners clad in lifejackets and sipping from coffee cups; Morse stops to exchange news after the long winter.Finally, we climb into a moored boat.

“The class has the same principles as a community garden,” Morse explains, “with master gardeners instructing novices on how to grow food. It’s just that it happens to be oysters—quite unusual, rarified, and fairly exotic, much more so than even the most heirloom of tomatoes or foreign of squashes.

“They get beautiful oysters, but it’s as much about engaging with the environment. There’s the sit-down education, where they learn about biohazards and invasive species, but then they have to actually build some of the equipment they use.” He nods towards the groups around us. “Friendships grow.”

We clamber into a battered aluminum skiff and motor out into open water, heading towards Lowe’s Cove, where the bags were stowed the previous fall in water deep enough that winter ice wouldn’t crush them. Morse, in fisherman’s overalls and thick gloves, is at the helm. We tie up to a buoy attached to a heavier line running on the bottom, with racks of mesh bags tied off at intervals. With us are Alex and Jim, two eager newbies, who’ll haul the lines.

Morse snags the line of the first rack and runs it through a cleat, then hands it to the two men. “Haul away, boys!” he calls over his shoulder. Their enthusiastic response sets the boat rocking wildly as a wire box the size of a lobster trap comes abruptly half over the rail, showering everyone with frigid water and tendrils of deep-green kelp. Grunting, Morse hauls in the 50-pound box filled with mesh bags, each holding one gardener’s crop, then moves on to the next. More racks come aboard, some with mysterious dents and tangled lines. “You never know what you’re going to find,” he says. “Lines all twisted and knotted up from winter storms.”

An hour later, the last rack recovered, the whole crew piles back into their vehicles and heads off to Great Salt Bay Farm & Heritage Center, where the first-years will count spat, then sew them into their very first bags. The old-timers dump their bags, discarding dead oysters, then washing the live ones to get any accumulated marine crud off them before putting their crops into larger mesh bags for the summer growth season.

Based at the farm is the Damariscotta River Association, which, in the person of Sarah Gladu, has largely taken over the program. She’s a good teacher and opens my eyes this day to yet another gift of the oyster. “Everyone talks about hands-on for kids,” she remarks, surveying the motley, mostly older, crowd, “but it’s equally important for adults. Oyster gardening is hands-on, full-body engagement. People slip in the mud, get wet, get cold—there are all kinds of ways of being engaged. And they do become marine stewards, and they do get interested in the water quality of this estuary.”

A tractor and flatbed trailer arrive, the bags are stowed, and then it’s time for a mile’s stroll down to the bay through salt meadows filled with goldenrod and milkweed and purple loosestrife. As we wait for the tractor on the shore of the lease site—a clamshell-shaped cove filled and emptied by the tide—I talk to John Swenson. This lanky, grizzled retired engineer was in the second class and has carried on ever since. I’ve watched him since we started the day, and he seems to be a leader, moving with experience from task to task and bringing others along with him.

I look at the group, most in rubber boots, gathered in clumps and chatting amiably. “These people, they’re mostly retired, from all walks of life,” Swenson notes.

He looks around. “My group had a retired IBM executive, a UConn professor, a body-shop owner. There are a few couples, but it’s mostly men in their fifties and sixties looking for an interesting way to get out on the water. It’s not onerous: Move the racks once a year; every two weeks clean off the marine life that sticks to them, summer through fall. If you have to miss, there’s always someone who’ll clean your bags for you.”

And why 1,000 oysters, the maximum gardeners are permitted? “That’s about what a family can eat in a year,” Swenson replies simply. “Of course, you get to be pretty popular.”

ONE HUNDRED THOUSAND OYSTERS: OYSTER STEVE HAS A SECRET

“Oyster Steve” Patterson, shellfish field manager at Roger Williams University in Bristol, Rhode Island, is also a marine educator who works with oyster gardeners. Unlike in the Maine model, however, Patterson’s oyster gardeners only babysit their oysters, giving them up at the end of each season to be planted in restoration beds to repopulate Rhode Island’s waters.

We’re barreling down a back road in Patterson’s pickup, his Lab, Lila, leaning in from the back seat now and then to lick my ear. We’ve entered a marsh wilderness about an hour from Bristol. He tells me that I might want to roll up my window for the next bit, and we enter a stretch where marsh grass and brambles screech against the truck’s sides as we bounce through big ruts before finally pulling up in a small clearing. We don hip waders, and he hands me a walking stick. “To keep you upright,” he says laconically.

Earlier, in his office, Patterson had started my visit with a question. “Do you know,” he asked, bushy eyebrows raised above a classic sun-touched Irish face, “that our oysters have a secret?” By “our,” he meant oysters spawned at the RWU hatchery. He’d taken me through Rhode Island’s 1995–99 Dermo disaster and what followed: the search for tiny reservoirs of survivors to breed for repopulation.

Eventually, it was successful, so much so that the spat quickly outgrew the lab’s capacity to feed them. Working with world-class aquaculture expert Dale Leavitt, his boss, Patterson started an outreach program to find oyster gardeners who owned a coastal tidal property and dock to which a floating tray holding 6,000 to 10,000 spat could be attached. Today, more than 100 gardeners are spread over coves and ponds and inlets from Bristol to Block Island, taking babies the size of a little fingernail in early summer and returning almost-one-inch adolescents in late fall for planting in restoration beds. “The survival at one inch,” Patterson explains, “is 70 percent, versus almost nothing if they’re smaller. In two years, I think we had maybe 100,000 oysters to plant. To date, our gardeners have raised six, seven million oysters for restoration.”

Patterson wades into a tidal pond. Low tide has exposed the shore, and I can make out thousands of oysters in shallow, mounded ribbons, imagining how many thousands more still lie underwater. (I also understand the utility of the stick, which I use as a lever when I sink up to my ankles in mud.) Patterson reaches down and pulls up what looks like one of those court jester’s hats, with triangles of material rising in a ring. Except that it’s entirely the green-beige of algae, and each triangle is a six- to eight-inch oyster jutting straight up from a surf-clam shell about the size of his hand. I’ll travel the length and breadth of New England’s coast for this story, but never again will I see oysters this large—longer than my hand and with deep wells on the cup side.

“It’s called an oyster crown,” Patterson says, handing it to me. “They grow straight up like that until the base shell dissolves, and then they become singles. There are a lot of things you see here that you don’t see anywhere else.” He points to another super-sized oyster, this one with a much smaller juvenile attached: “Here we have a natural set. And since these oysters survive past adolescence, and most of these are 6-year-olds, you can actually see what an oyster reef looks like at low tide. Let’s find you a banana oyster.” And he does, eventually, its shell curving gently, a full foot long and two or three inches wide.

As Patterson searches, he talks about the reef’s biodiversity, how this former dump site now shelters more than half a million oysters—and all the species drawn by them, from the raccoon whose tracks we followed in, to the blue heron who flew off as we drove up, to the much smaller creatures living on and around the reef.

“I have underwater photos,” he says, “showing thousands of glass shrimp grazing on the algae growing on an oyster shell’s surface. I call them my rabbits. Because then, of course, we get our carnivores that come in to eat the rabbits: all sorts of crabs, lobsters, flounder, tautog, oyster toad fish, silversides.

“And ocean fish come in to lay their eggs. I very often find eggs in our restoration sites. Historically you had estuary fish like striped bass that don’t spawn in saltwater, they don’t spawn in freshwater; they look for those saline zones where their babies have a place to hide so they don’t get consumed so quickly.” Those saline zones, of course, are the oysters’ preferred waters.

Two hours later I find myself in the comfortable living room of a retired couple from Pittsburgh, Gene and Joyce Corl, near Wakefield, looking out on Segar Cove. They’ve proudly shown off their dock and its rack of oysters. “We love what we have here,” Gene says. “This is a way to help out. You’re contributing.” Joyce nods, looking at her husband. “It’s such an amazing story, the oysters,” she adds, “and we’re one part of it.” Her husband shrugs. “It’s not hard,” he says, “and maybe if we get the oyster back, we get shrimp. Maybe someday I’ll see flounder under the dock.”

Patterson’s secret? “We’re not allowed to say our oysters are immune to Dermo,” he told me, and I can hear the wink in his voice, “but let’s just say they show a marked ability to live in the presence of the disease, and that they pass this on to other generations.” These Roger Williams University oysters are the descendants, now several generations strong, of the survivors of that 1995 outbreak—and this reef, teeming with life, is proof that they might once again thrive on their own along New England’s coast.

FIVE MILLION OYSTERS: IF YOU CULTCH IT, THEY WILL COME

A few years back, the EPA gave Wellfleet, Massachusetts, a failing grade for water quality where two creeks flowed into the harbor. “Moderately to severely degraded” from too much nitrogen, parts of the harbor were turbid and anoxic, plagued by periods of naturally occurring nutrient overload.

“Several consultants proposed spending up to $60 million over many years to pay for the installation of a new waste-water management system,” recalls Curt Felix, at that time vice-chair of the town’s wastewater-management committee. This for a town of about 3,000 year-round residents. “And then a former Woods Hole Oceanographic Institute scientist suggested oysters.”

“Oysters aren’t just filter feeders that purify water,” Felix explains enthusiastically. “As they naturally eat algae—where nitrogen is bound in the plant matter—they remove it from the water, which, together with dissolved minerals, makes their shell. So they not only help restore nutrient balance and make the water clearer, but they also reduce the ocean’s acidity with the calcium carbonate in their shells, like Tums—ocean acidification being another problem associated with global warming.”

A diminutive, fiftyish fellow with the stringy build of a runner, Felix speaks in full paragraphs, pausing in between to gather his thoughts before the next burst. With his background in marine biology, I’d imagined that he’d been a valuable asset in convincing the townspeople to fund a project that, as he said, “had never really been tried on a large scale, and which we all were going to pay for.”

It turned out that the Massachusetts Audubon Society had done a pilot oyster-reef restoration project in the harbor with promising results, while Dr. Frankić had supervised a graduate-student thesis project there as well. The scientists and Wellfleet’s shellfish constable surveyed 14 acres of inner harbor and in 2011 laid down clamshell near the town pier, taking advantage of Wellfleet’s well-established natural set and cultching to jump-start a large oyster population that would filter water coming from the degraded creeks. They get the shell—surf clam—free from a processing plant in New Bedford that’s happy not to have to pay to dump it.

“At first, they used to pile the shells on a barge,” Felix explains when I ask how cultching works, “and shovel them over the side by hand as the barge puttered along. Then they got the bright idea of repurposing a road-sanding apparatus” that usually sits on the back of the truck and throws sand out in an arc behind it.

On this early-summer day, we’re standing by a primitive wheelhouse stuck onto the back of the barge, which is moored to the town pier at slack tide. A truck eases up to the edge above us, then dumps a full load of shell down into the spreader’s maw. At the helm is Andy Koch, Wellfleet’s shellfish constable. Koch is stout about the middle, but tall, with hands like spades and feet just as large. Felix casts off, and we motor out to the first cultching grounds. Koch idles the boat, and Felix hustles to start the spreader motor. Then we move slowly forward as shells begin spewing out the back of the barge to settle in a thick ribbon on the bottom, providing not just a happy place for spat to settle but the foundation and structure for, over time, the growth of an oyster reef. Then back to the pier, where another truckload waits. Koch will make this trip when the tides are right for several hours each day over 10 days to two weeks.

“The oysters spawn,” Felix says, “when the water gets above 68 degrees here, about the first week of July. So in June we have to get ’em all in, the shells. The oysters spawn, and spat results, little tiny things floating around looking for a rough surface. They’ll attach to other oysters, so you have a multiplier effect. If you maintain a critical minimum population, it can be self-sustaining.”

“It’s like you put your money in the bank,” Koch puts in, “and our harvest is the interest. I was a fin fisherman, and fishermen know that structure is life. If you have structure on the bottom, you can have gold. Small fish hang out, crabs and little shrimp live and reproduce, and then it takes off from there—small minnows, striped bass, move in at high tide. You get menhaden hanging around the reef. We even had turtles—hundreds of rare diamondback turtles.”

So what actually happened? “In the last three years,” Felix says proudly, “we managed to produce a 70 percent reduction in nitrogen, with an oyster population that went from a couple thousand to more than five million. We’ve had tremendous success.” Instead of tens of millions of dollars, the total cost of the project has been less than $250,000, with water quality now rated excellent, and species whose presence had diminished in recent years—terrapin turtles, bluefish, menhaden—frequenting the project area. One notable visitor who spent two days directly over the site was Katharine, the tagged great white shark whose coastal peregrinations have fascinated so many.

Back at the dock, Frankić, who comes down to Wellfleet for periodic monitoring with her graduate students, shows me the cultch sites. “If you look at Wellfleet Harbor on Google Earth,” she says, “it looks like a giant womb. It’s made for spawning oysters.” We’re walking a narrow strip of beach opposite the long finger of pier that juts out into the harbor, and Frankić is pointing to the muck that during the 2013–14 winter storms covered millions of oysters, killing them and putting a dark cloud over the project. “I cried when I saw this the first time,” she tells me, “but that’s nature. You never know what’s going to happen. So this summer, we try again: cultch and see what happens.”

Demonstrating the extraordinary resilience of this enduring species, though those storms killed about one-quarter of the stock, by fall 2015 following a successful summer spawn, that number was back up to just under four million, the harbor water sweet and clear.

A BILLION OYSTERS

Oysters clean our water. Oysters create structure for biodiversity. Oysters sequester pollutants. Oysters put fishermen to work. If a two-acre plot in Wellfleet Harbor can grow five million oysters in just two years, imagine what such plots could do in 10 years, 15 years, a generation: a billion oysters strategically deployed up and down the coast.

In 2010, New York landscape architect Kate Orff entered a national contest looking for ways to protect Lower Manhattan from rising ocean levels and storm surges—the kind that Hurricane Sandy would bring two years later. She proposed planting oyster reefs offshore in huge swaths to absorb and deflect such follow-ons to climate change. Her idea, called “oyster-tecture,” won first place, and a federally sponsored program is now getting off the ground on Staten Island.

A final note: Many of the researchers I interviewed rarely eat oysters. “If I were raising white rhinos or ivory-billed woodpeckers because I found a few,” Patterson says, “and all of a sudden we had 500 of them, I wouldn’t advocate eating 250 because we have so many. We don’t exactly advertise what we have, because people would come and help themselves. It’s not illegal.”

So the next time you’re at your favorite raw bar with a dozen Pemaquids or Wellfleets or Matunucks glistening on their beds of ice, say a small prayer of thanks to this magnificent mollusk. So delicious, yes, but so good to us and so good for our environment, a truly miraculous creature.