Scientists seek defense against invading
species in Great Lakes
By Tom Meersman
Minneapolis-St. Paul Star Tribune
Published June 29, 2004
MASSENA, N.Y. - Coast Guard Petty Officer Ward Ordway
boarded a foreign ship in the St. Lawrence Seaway, ready
to look into its dark, dank bowels for stowaways. Not
human troublemakers, but aquatic creatures that could
escape the murky depths of ballast water tanks and invade
the Great Lakes.
Ordway and an assistant tested the stored water to make
sure it was salty enough to kill any pests carried from
foreign ports. Tests like this are the U.S. government's
main bulwark against alien species.
Yet a gaping hole exists in this line of defense.
Invading creatures from abroad still can reach the Great
Lakes - on oceangoing ships that don't get tested. The
Coast Guard's 11-year-old ballast-monitoring program exempts
from testing three out of four vessels heading into the
lakes from ports around the world.
These untested ships - nearly 3,500 since 1995 - are
loaded with cargo, rather than ballast water. In theory,
their nearly empty ballast tanks shouldn't be teeming
with foreign creatures.
But they are, scientists have discovered. Even ships
with nearly empty ballast tanks can carry millions of
tiny invaders in residual water and mud that can end up
dumped into Great Lakes ports.
Once established in the world's largest freshwater lake
chain, an invader like the European round goby can become
a permanent resident, out-eating, out-reproducing and
overpowering native species.
Two-thirds of the 79 non-native species discovered in
the lakes since the St. Lawrence Seaway opened in 1959
almost certainly arrived in ballast tanks, according to
recent U.S. and Canadian research analyzed by the Minneapolis
Since the testing program began in 1993, 14 invaders
from Europe and elsewhere have been discovered in the
lakes. It's impossible to say whether they slipped through
- or had arrived before the program began.
Coast Guard officials defend their program and say that
it is probably stopping some invaders, even though there's
little evidence to prove it.
One reason that tiny creatures from abroad continue to
be discovered is that scientists are looking harder for
them, said Lt. Cmdr. Kathy Moore, chief of the Coast Guard's
environmental standards division. Researchers may be finding
invaders that have lived in the lakes for years and were
not noticed until their populations increased, she said.
Concern about the invaders prompted Congress in 1990
to order the Coast Guard to begin a testing program in
the Great Lakes. The rules adopted three years later are
more stringent than those for most other U.S. ports.
If a ship heading toward the seaway has water in its
ballast tanks, its captain is required to exchange the
water on the open sea. In theory, the saltwater will wash
out or kill the organisms picked up in foreign ports before
they can be carried into the Great Lakes. Then these water-laden
ships are tested by Coast Guard officers as they enter
To critics of the program, such tests mean nothing.
One of the doubters is Eric Reeves, a retired Coast Guard
commander who was responsible for the ballast-monitoring
program in the Great Lakes from 1993 to 1998. He now says
the inspection program can't prevent new invaders.
Reeves lost faith in saltwater as a defense against invaders
after he studied scientific reports on aquatic species.
Reeves said he discovered that some organisms from foreign
ports can tolerate salinity and are not killed by the
ocean water. And he learned that invaders were carried
in the slop and sludge of ships that were exempt from
inspections. "I realized that we really didn't have
a program designed to solve the problem," he said.
Moore, of the Coast Guard, acknowledged that the program
is not perfect, especially for hardy invaders and those
that burrow into the mud at the bottom of ballast tanks.
"If they're embedded in sediments, they're not something
necessarily that can be easily flushed out," she
For several years, the Coast Guard has been considering
whether stricter ballast-water regulations are needed
on the Great Lakes. Lake scientists generally support
the idea. Shippers worry that new regulations might make
their business less competitive.
Anjuna Langevin, director of navigation and enforcement
for the Shipping Federation of Canada, an industry group,
said that a sudden change in ballast-water restrictions
in the Great Lakes could put the region at a competitive
disadvantage and tempt ship owners to move elsewhere.
Langevin said that technology to remove invaders from
ballast water is unproven and likely would cost at least
$1 million per ship. Experimental methods include filtration,
exposure to intense ultraviolet light, oxygen removal
and chemical treatment.
The largest risk comes from relatively few ships. Vessels
from abroad, known as "salties," make about
500 trips into the Great Lakes each year, according to
the Coast Guard. By contrast, most shipping traffic is
from "lakers" - vessels that move only within
the Great Lakes and make thousands of shorter trips each
If a solution is found for the Great Lakes, it might
benefit other U.S. waters, which offer invaders easy access.
Chesapeake Bay contains at least 160 non-native species,
for example, and the San Francisco estuary is home to
more than 200 invaders. There are no locks to separate
these waters from the oceans.
After more than a decade of study, the International
Maritime Organization, a U.N. agency, proposed worldwide
standards earlier this year that would affect existing
ships beginning in 2014.
But the treaty contains provisions that could postpone
the deadlines. It will also take years to ratify.