Are invaders riding on ships' hulls?
By Jeff Alexander
Grand Rapids Press
Published January 17, 2008
MUSKEGON -- Disinfecting ballast water in ocean freighters may not keep the ships from importing more foreign species into the Great Lakes, according to a new study.
The reason: Some foreign species enter the lakes on the hulls of ocean freighters, according to a study by University of Notre Dame biologists John Drake and David Lodge.
The scientists claim the problem, called hull fouling or biofouling, may pose as serious a threat to the Great Lakes as exotic species imported in a freighter's ballast water tank.
"Overall invasion risk from biofouling may be comparable or exceed that of ballast water discharge," Drake and Lodge said in an article published recently in the scientific journal Aquatic Invasions.
Congress has been debating legislation for several years that would regulate ballast water discharges from freighters. The U.S. Coast Guard, which regulates the shipping industry, also has been working for years on a ballast water discharge standard for ocean freighters that visit Great Lakes ports.
Previous proposals did not address the ships' hulls.
Conclusions from the study were based on samples collected from the hull of a South American freighter drydocked in Ontario. They found between 100 and 200 different species on the ship's bottom, including eight that have not yet been documented in the Great Lakes.