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.
