The Chesapeake Bay needs federal and even international help to prevent "invasions" by exotic fish, plants and parasites carried as stowaways aboard globe-trotting ships calling in Baltimore and Norfolk, Va., a new report says.
Warning that visiting ships play "ecologic roulette" with the bay by discharging ballast water teeming with non-native organisms, committee of scientists, shipping agents and state and federal officials says an individual state like Maryland can do little to combat the threat.
In a report to the Chesapeake Bay Commission, the panel calls for national voluntary guidelines on discharge of ballast water in coastal waters. If ships do not comply, the U.S. Coast Guard should impose regulations, the panel says.
The report also calls for international regulation of ballast water intake and discharge, because cargo ships and tankers visiting the bay come from at least 48 ports around the world.
The bay commission, which represents state legislatures in Maryland, Pennsylvania and Virginia, is due to act on the panel's recommendations next month.
An accidental introduction of foreign fish or plants could harm native species, undermining the 11-year-old effort to restore the Chesapeake, said Ann Pesiri Swanson, executive director of the commission.
"As we spend millions and millions of dollars and regulate people to improve water quality in the name of living resources," Ms. Swanson said, "it would be a shame to have a new living resource introduced into the [bay] and upset the balance."
Ballast water is believed to be the prime source for invasions of rivers, lakes and bays.
Shipping has been blamed, for example, for bringing the troublesome zebra mussel from Europe to the Great Lakes and for carrying fish-killing red tides from Japan to Australia. Ships pump water into below-deck tanks or cargo holds to ensure stability during an ocean voyage, and captains release ballast when approaching port.
A single large ship can carry millions of gallons.
The problem is that whatever is present in the water -- including juvenile fish, eggs, plankton, bacteria and viruses -- comes aboard in the ballast.
Many of the organisms can survive for weeks inside the ships and are released when the ballast is pumped overboard.
Zebra mussels, the most notorious of the foreign invaders, have spread rapidly since showing up in the Great Lakes less than a decade ago. The fast-growing mollusks, which attach to any hard surface, can shut down water plants and power stations by clogging their intake pipes.
The tiny mussels now live throughout the Northeast, in the upper Mississippi River and in the upper Susquehanna, the bay's largest tributary. Operators of municipal water systems and power plants nationwide are expected to spend $3 billion in the next decade to protect their facilities from the creatures.
The Chesapeake already has been invaded by other exotic species, such as the freshwater Asian clam and the underwater grass hydrilla. Some scientists even speculate that the devastating oyster parasite MSX, which suddenly appeared in the bay in the 1950s, was brought here in ship's ballast.
Baltimore and Norfolk, among the busiest ports in the nation, are likely places for an invasion because of the vast quantities of ballast discharged by ships arriving from Europe, Asia and Latin America. Together, the two ports receive 3.2 billion gallons of ballast water a year, a recent federal study determined; Norfolk ranks second nationally and Baltimore fifth in volume of ballast water received.
Many of the organisms released by ships into the Chesapeake do not survive. But scientists from the Smithsonian Environmental Research Center, near Edgewater in Anne Arundel County, have found living organisms in more than 90 percent of the 70 vessels they have sampled.
Ships bound for the Great Lakes now are required by federal law to exchange their ballast at sea before entering coastal waters. Salty water kills many fish and plants picked up in freshwater ports.
One major Chesapeake fleet owner, the Navy, with 96 vessels based in Norfolk, Va., already has pledged to protect coastal waters worldwide through at-sea ballast exchange.
Effective Nov. 1, the Navy adopted a new environmental protection manual, which includes a requirement that whenever possible, any vessel that has taken on ballast water within 12 miles of a coastline must exchange that ballast at sea before reentering coastal waters.
Moreover, the Navy has awarded the Smithsonian a $500,000 grant to sample military vessels for foreign organisms in their ballast tanks, said Steven G. Olson, an environmental engineer based in Norfolk who is the Navy's Chesapeake Bay coordinator.