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Volume 3, Number 3
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A New Bay for the Oyster?

By Michael W. Fincham

Loading oysters onto an oyster recovery ship

On the last Saturday of October, there's an oyster party out on the Choptank and the Chester, two Maryland rivers littered with broken-down reefs and scattered, disease-ridden oysters. Watermen are invited as well as environmentalists, scientists, politicians and the press.

There have been other oyster parties along these rivers in recent years, but these were planting parties organized by the Oyster Recovery Partnership, a coalition of organizations, agencies, scientists and volunteers who want to put oysters back in the Bay. On this Saturday, however, there's an old-fashioned fishing party, a "trying of the grounds," a test case for the idea that oysters can be restored — and that the Bay's resilience can be revived.

Oystermen in narrow, deadrise workboats driven by diesels and old car motors chug out in the pre-dawn light to oyster grounds called Emory Hollow and Blunts and Bolingbroke Sands. They haul out their long-shafted hand tongs and hop up onto the narrow edge of their open cockpits. As dawn breaks there are several workboats parked over each oyster bar with watermen balanced on their washboards waving their arms and working their tongs back and forth as they dig into a pile of oysters along the bottom.

There will be no October surprise this Saturday morning. Charley Frentz, the man who's throwing the party, already knows what kind of oysters the watermen will find on these bars. "It will be a golden opportunity to actually see these 4-, 5-, and 6-inch oysters that we've got in the Bay now," says Frentz, director of the Oyster Recovery Partnership. "They are gorgeous." He knows they're gorgeous because his organization put them there three years ago and scientists have monitored their growth ever since.

Think of the event as an opening, a groundbreaking — which it literally is. These oyster grounds were closed for business for three years, while the Oyster Recovery Partnership under Frentz reorganized its approach to restoration. The new plan called for stepped-up spawning of disease-free oysters, new mass production techniques for moving and planting oysters, the establishment of off-limits sanctuary bars where watermen could not harvest and other managed reserve bars where they could, on occasion, go fishing for oysters.

These three oyster bars are the test case for the new approach and a trying ground for the new director. "Everybody has been very patient the last three years with me," says Frentz, who took over as director in 2000. "They have been giving me the benefit of the doubt on these managed reserves and sanctuary programs and how we are cleaning the bars, how we are using the watermen. And until these boys get these oysters on October 30th, I don't have a deliverable."

Two Estuaries: The Old and the Now

The great oyster dieoffs of the last four decades have changed the ecology of the Chesapeake. When H.L.Mencken, back in the 1940s, called the Bay "an immense protein factory," the estuary was turning out more seafood per acre than any other body of water in the world — and oysters were one of the reasons. Sitting silently along the bottom, oysters were, in effect, the heavy machinery on the factory floor.

The most profitable species in the Bay, oysters were both a foundation fishery for the region's economy and a keystone species for the Bay's ecology. They built reefs, creating three-dimensional habitat for crabs and finfish and dozens of other species. They held barnacles and mussels and jellyfish larvae on their tough shells. They were food for blue crabs and for odd little animals like oyster drills and ugly, big-toothed toadfish. More importantly, oysters on the bottom were indefatigable filter feeders, noiseless vacuum cleaners quietly sucking nutrients and phytoplankton out of the water. Stacked in huge beds, oysters were engines for clarity, magnets for biodiversity.

Don Meritt and his staff have developed techniques for spawning, feeding and setting the native oyster.

What's the best way to restore oysters in the Bay? Replanting with the native oyster? Or importing an oyster from overseas? Don Meritt (above) and his staff have developed techniques for spawning, feeding and setting the native oyster, Crassostrea virginica. The aquaculture hatchery he runs at the UMCES Horn Point Laboratory is the major source for the native oysters now being replanted in Maryland waters. Ken Paynter and Tim Koles (opposite page, left and right) get ready to test-plant oysters from China, Crassostrea ariakensis, in the Chesapeake. Sterile by design, those oysters are fast growing (in the lab) and disease resistant (so far). Which will be king in the once-great shellfish Bay?

And then, in only three decades, they were nearly gone. Two parasites, MSX and Dermo, infected the oyster grounds of southern Virginia in the early 1960s and spread steadily northwards into Maryland waters during years of drought or low rainfall. By the early 1990s populations of Crassostrea virginica, the native species, were down to less than one percent of their historic levels.

There were less drastic declines with three other great filters: forests, wetlands and seagrasses. These natural systems are the major buffers in estuaries like the Chesapeake, the primary causes for water clarity, the sources for ecosystem stability. They help absorb, in different ways, the intermittent insults of tropical storms and the ongoing onslaught of sediments and nutrients that can overwhelm and overfertilize the estuary.

In theory, these buffers are reservoirs for resilience. When one buffer declines — say oysters — then the others would still be at work: filtering, absorbing, mitigating. The Bay would still have a built-in capacity to bounce back. When several buffers trend down at the same time — say, oysters and seagrasses and wetlands — then funny things start to happen. Feedback loops activate. One trend starts to magnify another. Ecosystem change accelerates.

The end result is regime change: the ecosystem transitions from one self-sustaining state to another. The Chesapeake over the last three decades has shifted from an ecosystem driven by bottom dwellers and benthic processes to an oysterless ecosystem driven by plankton blooms in the water, bacterial blooms along the bottom and large, low-oxygen zones. These two estuaries are very different. And the new state has its own built-in resilience — it can resist recovery.

Oyster Futures

When watermen start fishing the Choptank and the Chester in the first light of the last Saturday in October, they'll like what they'll find. "On these three bars," says Frentz of the Oyster Recovery Partnership, "we probably have more oysters for the watermen than they caught in the entire Chesapeake last year." Frentz will have his "deliverable," one that's simultaneously impressive — and sobering.

For the onlookers on the press boats, a scene full of tongboats clustered over oyster bars will look a lot like an old photo from the past, from a half century earlier when the Bay was still a protein factory. It's more likely a snapshot of what the future will look like.

The oysters coming out of those rivers were put there by science, not by nature. They were born in a laboratory, not in a river. They are the product of progress in breeding disease-resistance, in turning out larger numbers of hatchery-spawned oysters and in getting them planted in the right places.

Research results like these are the other "deliverables" from the oyster recovery crusade. They are starting to answer some of the big questions about the future Bay: Does oyster restoration work? Will it help the whole ecosystem bounce back? Can it kick off a new round of regime change in the Chesapeake?

The research answers are incomplete, impressive — and also sobering.

The progress that put oysters in the Choptank and Chester should continue. With each passing year, Stan Allen at the Virginia Institute of Marine Science (VIMS) is able to breed yet more generations of native oysters with stronger disease resistance. At the UMCES Horn Point Laboratory, Don Meritt is setting up a hugely expanded, industrial-level oyster hatchery. The near future could bring an exponential increase in the amount of native seed oysters available for planting.

The good news from the field is that reef restoration works — in places — and when it does "good ecological things happen," according to UMCES scientist Ken Paynter. Wherever the Partnership has planted oysters, Paynter has taken samples in every season except the dead of winter, sending divers down with cameras and quadrats and grab bags to videotape the reefs and bring up oysters for growth and disease analysis. "When you do restore an oyster reef, then the oysters grow and survive. You get animals recruiting to form a diverse benthic community in the reef," he says. "And it appears that oysters filter lots of water."

The bad news: reef restoration is working only in low-salinity regions. Everywhere else they went, Paynter and his divers saw oysters grow well for two years, then die quickly from Dermo or MSX, as the two parasites continue to invade and overwhelm oysters in moderate to high salinity waters.

Oyster restoration with native oysters, says Paynter, will work only in low-salinity waters below 10 parts per thousand. Healthy high-filtering oysters could be restored on tens of thousands of upriver acres, totaling perhaps 25 percent of the Bay's historic oyster grounds, according to Paynter's rough estimate.

That's a significant chunk of the ecosystem where rebuilding oyster reefs could restart water filtering and biodiversity and other "good ecological things." But it still leaves 75 percent of the old oyster grounds stuck with a dwindling supply of disease-ridden oysters.

Can native oysters drive a major ecosystem rebound, a regime change towards a restored Chesapeake? According to the research so far, that's a little like kick-starting a four-cylinder motor that's got only one spark plug firing.

 Two people making an oyster float to grow oysters.
Progress and its Paradoxes

On a mild April morning earlier this year, Ken Paynter and his field technician Tim Koles pulled on their dark, rubbery dry suits and went wading in the chilly waters off Solomons Island. Pushing into chest-deep water, they floated between them a rack of wire cages holding dark shells, each the size of a thumbnail. The event was a first for Maryland: the test-planting of oysters from China in the Chesapeake Bay. There are a number of paradoxes in the progress of oyster science. The success with replanting native oysters (albeit, only in low salinity waters) has raised some optimism about planting non-native oysters in the high-salinity waters that make up most of the Bay's oyster grounds. Since reef restoration works, it might work more widely if we can find an oyster that won't get sick from MSX or Dermo.

A second paradox: Chinese oysters may be introduced to repair oyster grounds that were ruined by an earlier introduction of Japanese oysters half a century ago. Forty years after MSX began devastating oyster beds in Delaware and Chesapeake bays, Gene Burreson of VIMS was able to prove that MSX was a natural parasite carried by Crassostrea gigas, a Japanese oyster carried into the Bay by oyster growers, scientists or international shipping. Gigas, it turned out, does not thrive in the Bay, but its parasite, MSX, does.

The oysters that Paynter and Koles are planting are called Crassostrea ariakensis, or the Suminoe oyster. The known native ranges for the species include northern China, western Korea and southern Japan. Paynter's test oysters, however, never lived in Asian waters. They were conceived in a lab in southern Virginia — as were their parents and grandparents. These third-generation lab specimens were also crossbred for sterility by Stan Allen of VIMS. In both lab and field tests, they have grown faster and fatter in Chesapeake waters than the native Crassostrea virginica. They are not reproducing in the Bay because they are, for now, sterile animals bred for testing. Most importantly they are not dying off from the local diseases.

No wonder a lot of watermen and some scientists think the Asian oyster holds a key to the future economy and ecology of the Bay. Paynter, however, is cautiously optimistic, calling the prospects promising. "It is not in my mind an either/or sort of thing," he says. "But rather virginica, the native oyster can do its job in lower salinity waters where disease is not as prolific, and perhaps ariakensis will be more successful in higher salinities. And we can accomplish restorations in both areas."

A final paradox: the road back to a restored Chesapeake will, it seems, require a detour through China. The stakes are high, of course, given the example of MSX, but the potential benefits are enticing. If it can reproduce in Bay waters, if it can build reefs, if it holds no unknown viruses or exotic diseases — those are a lot of ifs.

But if this Asian oyster keeps passing all its many tests, then there may soon be new biological engines on the floor of the Bay, turning plankton into protein and kick-starting once again the Chesapeake's famous old seafood factory. And October mornings in the future might see a lot more planting parties and fishing parties on a lot more rivers, all of them running clearer in the early morning light.

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