Blue crab populations in Chesapeake Bay have fallen more than 70 percent in the last 20 years, the result of uncontrolled development, sewage dumping and wastewater discharge. But now the bay is beginning to recover, thanks to an unprecedented cleanup effort involving states, the federal government and tens of thousands of volunteers.Colin Woodard
Four centuries later, many still agree. Millions have moved to the region, in part to enjoy the bay’s balmy shores and succulent marine life. From the yacht basins of Annapolis to the fishing fleets of Smith Island, from the crab houses of Baltimore to the bustling ports of southern Virginia, the Chesapeake is central to the lives and identity of the region’s towns and cities. Marylanders call it "the land of pleasant living."
But the Chesapeake is in trouble. Where Smith would have looked down to see fish hiding in meadows of sea grass, one can see nothing at all: The water is an opaque brown flecked with bits of algae and the occasional plastic shopping bag. Nine-tenths of its oysters have vanished, and scientists fear the bay’s signature blue crab is on the threshold of collapse. Blue crab populations have fallen by more than 70 percent in the last two decades, and this year’s catches are at an all-time low. Ducks, sturgeon and menhaden populations are a shadow of their historic levels.
But the Chesapeake is comparatively lucky. While other bays and seas around the world have been driven to ecological collapse over the past two decades, the people of the Chesapeake have been working to restore the ecology of the bay. Since the early 1980s, Maryland, Virginia, Pennsylvania and the District of Columbia have been working to improve sewage and industrial wastewater treatment in the Bay, protect wetlands and improve the health of fisheries. The effort has since grown to enlist numerous federal agencies and tens of thousands of bay residents. The result has been a resurgence of rockfish, striped bass and shad. But progress is offset by rapid suburban development, including a merging of Baltimore and Washington, D.C. suburbs.
"We’ve seen some modest improvements in the health of the bay, but much remains to be done," says Michael Hirshfield, vice president of the Chesapeake Bay Foundation in Annapolis, Maryland. "In the face of continuing population growth, even staying in place has been a serious challenge."
At first, people thought the bay would recover if pollution from municipal sewers and factories were reduced, but it’s turned out to be more complicated. "The Chesapeake and its watershed are one large system, and you have to look at problems on that level," says Ann Swanson, executive director of the Chesapeake Bay Commission, a tri-state legislative body. "If you’re managing striped bass, you have to look at the juvenile blue crabs that they eat. And if you care about blue crabs, you’d be crazy if you didn’t look at the state of sea grasses." And so on.
Like many bays and seas around the world, the Chesapeake has been overwhelmed by the activities of human beings along its shores. Fishing, channel dredging, clear-cutting and industrial pollution all played a role. But the most severe factor has been nutrient pollution—a deluge of sewage, livestock wastes and fertilizer run-off from cities, suburban homes and agriculture. The nutrients trigger massive algae blooms and can create huge "dead zones" of oxygen-less water. Fish, crabs and other organisms must abandon such areas or perish. The algae also snuff out sea grasses—the habitat of blue crabs and other creatures—by blocking sunlight.
"Reducing the nutrient input in the Bay is the primary, keystone objective for any clean-up," says Don Boesh, president of the University of Maryland’s Center for Environmental Science. Clean-up efforts have so far reduced the annual quantity of nitrogen nutrient entering the bay from 360 million pounds in 1985 to around 310 million pounds this past year. But the Environmental Protection Agency estimates that figure would have to drop to between 130 and 190 million pounds to restore water quality.
Achieving such a reduction will cost $8.5 billion over the next decade, according to the Chesapeake Bay Foundation. The funds, most of which would have to come from federal and state budgets, would finance further upgrades of sewage treatment plants and urban storm water systems, an expansion of forested "buffer zones" along the shore and land preservation.
There are some promising signs. In June, the six U.S. Senators who represent Maryland, Virginia and Pennsylvania asked Congress to come up with $660 million during the next five years to upgrade Chesapeake-area sewage treatment plants. Last year, state and federal officials announced a toughened, region-wide restoration plan that called for a 30 percent reduction in the urban sprawl projected for 2012, a tenfold increase in oysters by 2010 and a commitment to preserve 20 percent of the land in the watershed from development.
Others have been trying to restore the oyster beds that once kept nutrient-caused algae blooms in check. Oysters filter algae out of the water. Back in 1607, oysters were so numerous they filtered the Chesapeake’s entire water volume every three to four days. But decades of over-harvesting and, in the late 1980s, the appearance of two parasites—MSX and Dermo—triggered a collapse in oysters.
Now, at as little as one percent of historic levels, the oysters take a year or more to filter the Chesapeake. Virginia’s latest attempt to restore oysters is controversial. State scientists are introducing a disease-resistant Asian oyster they hope will be better able to survive in the altered bay. The Asian oysters are made infertile in an effort to prevent them from spreading out of control, but on rare occasions, some oysters regain their fertility. Maryland scientists are instead trying to rebuild native oyster stocks by building new beds out of shucked oyster shells and seeding them with native sprat, or baby oysters.
As for the blue crabs, "The real choice we have to make is to reduce harvesting pressure so that enough breeding-age crabs survive to reproduce," says Boesch. Indeed, if human pressures on the bay are cut back, the Chesapeake may be able to recover on its own.