Invasive species taking toll on lakes
Written by Oakland Press   
Wednesday, 22 March 2006 13:46

Oakland County has 47 lakes confirmed with zebra mussels, with the discovery in 2005 of the mollusks in Bush Lake near Holly and this year in Bald Eagle Lake in Brandon Township.

The spread of the nonindigenous species in Oakland County is following a pattern of moving from the Great Lakes to inland lakes via what Hugh MacIsaac calls stepping stones.

And once established, such invasive species are nearly impossible to remove, said MacIsaac, invasive species research chairman at the University of Windsor's Great Lakes Institute of Environmental Research.

"The big problem with invasive species is how to get them out.

"A friend of mine says the only real solution to zebra mussels is the next period of glaciation that will scour them out."

MacIsaac and other scientists, as well as policy makers, spoke Monday to a group of journalists at the Great Lakes Institute of Environmental Research about issues affecting the Great Lakes region.

It's been estimated, he said, that the rate of nonindigenous species entering the Great Lakes basin is 50,000 times higher than it would be if only natural forces were at work.

Humans and their modes of transportation, said MacIsaac, act to quickly move species around the world.

He added they create networks of places where invasive species move - the stepping stones, for example, that allow zebra mussels and other invasives to move from the Great Lakes to inland lakes and rivers.

"The networks we are most concerned with are networks that move either humans or cargo around the world," he said.

The fishhook water flea, a minuscule organism that fouls anglers' lines, moved from its native Black Sea probably through inland canals to the Baltic, from which it traveled to the Great Lakes. A predator and its relatives are likely responsible for a decrease in native zooplankton - tiny animals at the bottom of the food chain.

Researchers have found about 100 lakes in Ontario, said MacIsaac, with populations of fishhook water fl ea.

They're responsible for the possible extirpation of at least three species of zooplankton, so Ontario, said MacIsaac, is poorer by about 300 populations of the tiny animals.

Both money and effort should be directed toward preventing nonindigenous species from entering the basin in the first place, "rather than try to mitigate their effects once they're here ... because these things spread like wildfire," he said.

G. Tracy Mehan, former director of Michigan's Offi ce of the Great Lakes and former assistant administrator for water in the U.S. Environmental Protection Agency, said regulations have had some great successes in the Great Lakes, notably in reducing the pollutants entering the water from point sources.

He advocated, however, a systemic ecosystem approach to managing the lakes and dealing with invasives.

"We're barely in the ballpark," said Mehan. "We seem unable to muster the wit to deal with the scourge of aquatic invasive species coming into the Great Lakes.

"Our science has improved somewhat, but our risk management and regulatory procedures are still fairly primitive."

Gail Krantzberg, director of the Centre for Engineering and Public Policy at McMaster University in Hamilton, Ontario, said despite successes such as the reduction of phosphorus going into the lakes, the basin still faces challenges from chemicals and from nonpoint source pollution due to storm water runoff.

Pharmaceuticals, for example, are entering the lakes in increasing amounts, she said, contributing to a chemical soup.

"We have a chemical component then, albeit at very low levels, but the question is, what effect may it have on us?" asked Krantzberg.

"We need to know."

Chris Marvin, a research scientist at the National Water Research Institute for Environment Canada in Hamilton, said that while scientists documented decreases in the levels of "legacy toxins" in the Great Lakes such as PCBs and dioxin, they may have missed new and emerging chemicals that sneaked in under the radar screen.

He called it an "object failure on the part of scientists in government, academia and industry to get a handle on what was going on.

"We didn't ask the question, if we're taking a compound out, then what are we replacing it with?"

Regulatory agencies and researchers, he said, should "spend a lot more time focusing on new and emerging chemicals, rather than on legacy compounds like dioxins and PCBs."

 
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