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Great Lakes Article:

Alien species poised to hit lakes

Invasive critters found in sludge at bottom of ships' ballast tanks

Grant Lafleche
St. Catharines Standard
04/03/2002


Neither the absence of sunlight nor the freezing cold can stop a horde of alien invaders knocking at the door of the Great Lakes basin.

New research by a University of Windsor student has shown what many environmentalists have feared for years -- invasive species are hiding in the slime and sludge found at the bottom of ballast tanks on ships travelling the Great Lakes.

Sarah Bandoni, a PhD biology student and researcher at the university's Great Lakes Institute, said she has discovered microscopic eggs of tiny water-borne creatures can survive the harsh conditions of the ballast tanks for long periods.

When the water conditions are right, the eggs hatch.

"It is an evolved defence that allows these organisms' eggs to survive in these conditions," she said Thursday. "This means they can be introduced to the Great Lakes."

For years, alien species such as the zebra mussel or the round-eyed goby have wreaked havoc in the Great Lakes, pushing out domestic fish by attacking them or significantly altering their habits.

Most reached the lakes in the ballast tanks of oceangoing ships that enter the Great Lakes system via the St. Lawrence Seaway.

In order to protect the lakes from foreign invaders, ships are now required to dump their ballast before entering the seaway.

But there is more than water in the ballast tanks. At the bottom of the tanks is an unpumpable sludge. This sludge is not regulated and ships carrying it are regarded as NOBOB (no ballast on board) vessels.

When ships unload or take on cargo in the Great Lakes, they use lake water as ballast that gets mixed with the tank slime.

Bandoni's research, part of a joint Canadian/U.S. research effort, shows there is a potential for a foreign animal to rise from the sludge and invade the lakes.

Last year, she took samples from lake ships and tested them in the lab.

She found that the eggs of creatures such as water fleas will remain dormant until fresh water is added to the sludge.

Not even the near-total darkness of the ballast tanks prevents the eggs from hatching.

"It was thought that light was an important ingredient to hatching these eggs," Bandoni said. "Well, it isn't."

She suspects when fresh water is added to ballast tanks while in the lakes, the eggs hatch. When the ballast is dumped, the critters are free to roam the lakes.

Environmentalists have been calling for regulations to control the slime on NOBOB ships. However, no regulations have been passed requiring the removal or treatment of the sludge.

She is trying to classify the creatures that hatched in her lab to determine which ones could be a potential problem for the Great Lakes.

Some of the organisms will be those that are found worldwide, she said, and others may be domestic to the Great Lakes basin. Others, however, could be alien in origin.

As well, researchers at two American universities are testing the ballast slime for bacteria and other organisms that might find their way into the lakes.

Bandoni will take another series of samples of NOBOB ballast scum this summer.


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