From the Associated Press via the Detroit News and Free Press
Oceangoing freighters that claim to be empty of ballast water before entering the Great Lakes routinely carry dangerous foreign organisms, including saltwater algae, invertebrates and deadly bacteria, a new report says.
The University of Michigan and National Oceanic and Atmospheric Administration conducted a five-year study of freighters that enter the lakes through the St. Lawrence Seaway.
The study found that ships that register as having no ballast on board routinely carry thousands of viable organisms in muddy water that sloshes around in empty ballast tanks.
Those organisms can escape when ships take on and unload ballast water while in Great Lakes harbors. Ballast water is stored in huge tanks below deck to keep ships stable and is added or dumped based on the cargo load.
Researchers also found that two-thirds of the 42 ships sampled carried potentially deadly organisms in ballast water tanks that were supposed to be empty and clean, including cholera and cryptosporidium, The Muskegon Chronicle reported Tuesday.
In 1993, cryptosporidium from an unknown source contaminated Milwaukee's drinking water system, killing more than 100 people and making 400,000 others ill.
Zebra mussels and 181 other species imported to the lakes threaten to drive out some native species at the base of the Great Lakes food web, endangering a multibillion dollar fishery.
The study's authors said immediate action is needed to stem the flow of exotic organisms and pathogens entering the lakes in freighters' ballast tanks.
They said one possible remedy would be requiring all transcontinental freighters to completely empty and refill ballast tanks with salt water before entering the Great Lakes.
"These findings clearly indicate a need for development of either ship management or ... treatment processes that ensure that fresh or brackish (mildly salty) water residuals from offshore are not co-mingled with freshwater ballast discharged within the Great Lakes," according to the 285-page study.
Presently, ships heading for the Great Lakes are required to exchange any ballast water at sea and report their ballast-water load at a station in Montreal.
But most freighters headed for the seaway are loaded with cargo and carry no ballast; nearly 90 percent enter the lakes as being ballast-free.
Researchers downplayed the discovery of cholera and other pathogens in freighters' ballast tanks.
"We know there are pathogens in these ships, but we don't know of any outbreaks of disease associated with ships' ballasting practices," said co-author Fred Dobbs, an oceanography professor at Old Dominion University.
Environmentalist Cameron Davis said the study validated his worst fears about the government's failed attempts to shield the Great Lakes from new exotic species.
"Many invasive species act like a computer virus: once they get into the Great Lakes ecosystem they can clean it out," said Davis, executive director of the Chicago-based Alliance for the Great Lakes. "In the Great Lakes, we are operating without a virus protection program."
Michigan lawmakers are considering legislation that would require shipping companies to obtain a ballast water discharge permit to operate at the state's Great Lakes ports.
