Like oceangoing Trojan horses, ships calling in Baltimore carry hidden invaders: alien marine organisms that could damage the Chesapeake Bay, a scientist warned yesterday.
They reach the bay in the 200,000 gallons of ballast water released hourly by ship traffic to Baltimore and Norfolk, ballast picked up in ports around the world, said Dr. James T. Carlton, director of maritime studies at Williams College-Mystic Seaport in Mystic, Conn.
The ballast -- from Europe, Asia and Central and South America -- teems with tiny crustaceans, worms and the eggs and larvae of crabs, fish and shellfish that could harm the bay's native species, Dr. Carlton told the Chesapeake Bay Commission, a panel of bay-region legislators meeting in Annapolis.
"A major ballast-water invasion of Chesapeake Bay [by a damaging species] could happen at any time," said Dr. Carlton.
He is working with scientists from the Smithsonian Environmental Research Center in southern Anne Arundel County on a federally funded study of shipping's role in transporting non-native organisms.
While the Chesapeake has been spared major disruption so far by exotic marine life, Dr. Carlton said the routine release of ballast water amounts to "ecological roulette" that could have serious consequences for native fish, shellfish and plants -- and possibly even for humans.
Although ships have been visiting the bay for centuries, in a recent interview Dr. Carlton said releases of foreign marine organisms may be increasing because vessels are bigger and faster, and they journey here from more exotic locales.
The worst marine invasion in this country to date has been that of the zebra mussel, a small mollusk from the Black Sea that turned up in the Great Lakes in 1988, where it rapidly grew and clogged the intake pipes of power plants and even briefly choked off a town's water supply.
In just a few years, the mussels have spread to the Mississippi River and to the upper Susquehanna, where they could eventually reach Maryland. Utilities and municipalities throughout the East, including Baltimore, have spent millions to protect water supplies from the shellfish. The mussels also are crowding out native shellfish.
Ballast water from ships is believed to be the source of the zebra mussel, as well as of other invasions of foreign marine life.
