Alien species still
entering Great Lakes an expert says
Thursday, April 20,
BY BILL KRASEAN
Laws requiring cargo ships to dump their ballast water
at sea and not in the Great Lakes have lessened but not
ended the threat of invasive plant and animal species.
Allegra Cangelosi, senior
policy analyst with the Northeast-Midwest Institute in
Washington, D.C., said invasive species may still be slipping
into Great Lakes waters from residual ballast water or
by hitchhiking on hulls, sea chains and anchors.
Cangelosi, a 1978 Kalamazoo
College graduate who spoke here Tuesday and Wednesday,
said very fine water filters, potent biocides such as
ultraviolet light and other preventive measures are needed
to eliminate the threat of another invasion similar to
the zebra mussel or the Eurasian ruffe.
The two and several
other species have been introduced into the Great Lakes
when ocean-going vessels dumped their ballast water in
Great Lake ports.
Great Lakes water users
spend tens of millions of dollars on zebra-mussel control
every year, Cangelosi said, primarily to prevent the mussels
from clogging water-intake pipes.
The Aquatic Nuisance
Task Force estimates that the zebra mussel alone costs
municipalities and industries about $360,000 a year and
nuclear power plants $825,000 annually.
Introduced in the late
1980s, zebra mussels have spread to inland lakes and rivers
across North America.
Other invading species
of fish such as the sea lamprey, ruffe and round goby
have reduced the populations of native fish such as lake
trout, walleye, yellow perch and catfish, threatening
a sport- and commercial-fishing industry that is valued
at almost $4.5 billion annually and supports 81,000 jobs,
according to the Task Force.
nuisance plants, such as purple loosestrife, Eurasian
watermilfoil and hydrilla have quickly replaced native
plants, they said.
The problem of invasive
species is worldwide -- "every coastline that ships visit,"
Cangelosi said in an interview Wednesday. "It's estimated
that San Francisco Bay has a new invader every six weeks."
Once the Great Lakes
problem was recognized, Congress worked to protect the
world's largest body of fresh water by changing rules
governing the dumping of ballast water. Cangelosi said
ships must now exchange their original ballast water with
ocean water no closer than 200 miles from shore.
Flushing is never complete,
however, and residual water can remain, she said.
"I look at treating
methods that can be used on shipboard -- filters, UV light
and other ways to kill or remove plants and animals from
ballast water," she said. "Once we find methods, it's
up to ship owners to look at the economics and anatomy
of the ships, the ballast setup, and determine the best
"We want a suite of
tools for them to choose."