Ships bring in organisms that could harm bay

January 07, 1994|By Timothy B. Wheeler | Timothy B. Wheeler,Staff Writer

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.

Australian researchers have found toxic algae cysts in mud at the bottom of ship ballast tanks, Dr. Carlton said, and the discovery has prompted some experts to link shipping with an apparent increase in harmful algae blooms around the world.

There even is scientific speculation that at least one of the parasitic diseases devastating the Chesapeake's oysters, MSX, may have arrived on the East Coast in the 1950s in ship ballast. And cholera bacteria, which can cause outbreaks of intestinal illness, have been detected in ships in Mobile Bay.

Ships pump water aboard as ballast to keep from capsizing or foundering in rough seas. But the pumping also sucks up whatever is swimming or floating around the vessel. "Ships can pick up schools of fish, bring them to Chesapeake Bay -- how often this happens, I'm not sure -- and simply deposit them in the bay," Dr. Carlton said.

Indeed, scientists from the Smithsonian research center have found life -- from tiny crustaceans to entire schools of small fish -- in the ballast tanks of all but two of 27 ships they sampled in Baltimore in the past four months. The organisms collected so far represent all the major families of the marine animal kingdom, but some of the specimens are so unfamiliar that researchers are still working to identify them.

A similar study that Dr. Carlton did of ballast water carried by 160 ships calling in Oregon from Japan found more than 360 different species.

The Chesapeake is the largest East Coast recipient of ballast water, he said, with an estimated 13.2 million gallons discharged into the harbors of Baltimore and Norfolk every day.

What scientists don't know yet is how many of the organisms brought into the Chesapeake in ballast water can or will survive. Smithsonian researchers plan to focus on that in the coming months, said Dr. Greg Ruiz, a biologist involved in the study.

Survival may depend on a variety of factors, from water temperature and salinity to the number of organisms released.

Many previous invasions of alien marine life may have been overlooked, said Dr. Anson "Tuck" Hines, another Smithsonian researcher, because most of the organisms transported are small clams or crustaceans with no commercial value.

Largely in response to the zebra mussel invasion, Congress passed a law requiring ships bound for the Great Lakes to exchange their ballast in the Atlantic. Increasing the salinity level of ballast is likely to kill off any fish or organisms that might survive in the fresh-water lakes.

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