newcomers in lakes pose dangers to marine ecology
By Chen Chekki - The Chronicle-Journal
November 22, 2004
Alien species invading Lake Superior and disrupting the water basin and human activity is a growing problem, said an expert on the topic who visited Thunder Bay on Saturday.
Carl Richards has studied for the past 10 years how foreign plants, animals, fish and bacteria get dropped off in the Great Lakes through water held in the ballasts of ships.
The University of Minnesota professor, who came to the city for a public forum on invasive species, said empty cargo ships usually take in some water to keep them stable.
Taken into ships in such distant places as the Baltic Sea, Danube River and Black Sea, the ballast water then gets discharged when the ships come to the Great Lakes to pick up cargo.
But the ballast water often carries organisms not native to the Great Lakes.
Throughout the 1980s and 1990s, zebra mussel, quagga mussel, round goby and New Zealand mudsnails added themselves to Lake Superior’s ecoystem.
The Dreissena Bugenis: quagga mussell Dresissena bugensis, like the zebra messel and many other recent invaders, is native to the Black & Caspian Seas region,
Sea lamprey, which came in through ballast water from ships in the mid-1900s, devastated the lake trout populations in Lake Superior, Richards said.
Zebra mussels that were discovered in Thunder Bay in 1990 have clogged water intakes to power plants, city water systems and pulp mills, he said.
Many of the other alien species, Richards believes, are also having an ecological impact on the Great Lakes.
“We think some of these species might cause some of these native species to go extinct,” he said.
Lake Superior has taken in more ballast water than any of the Great Lakes and once the alien species are brought in, it’s virtually impossible to get rid of them, Richards said.
He said 70 per cent of the ships heading to the Great Lakes from around the world don’t stop much anywhere else before they arrive.
A possible solution to the problem is forcing ships to exchange ballast water once they get to the ocean, so the salt water taken in kills off the alien species in the ship.
The United States requires ships to do this, and Canada is talking about similar legal requirements.
Meanwhile, the problem of alien species exists in places elsewhere in the world.
“They have as much problems in Europe with our species being a pain in the butt over there,” Richards said.