Special Segments

Special Segment: Lake Invaders

Tuesday, November 09, 2010

Researchers are sounding a warning that there is a threat to the Great Lakes that may be worse than the Asian carp.

The new threat is literally eating up the basic building blocks of life in the lakes.

"We really are seeing the collapse of one of the largest lakes, food webs, in one of the largest lakes in the world," said Dr. Charles Kerfoot of Michigan Technological University.

Dr. Kerfoot has been surprised by what he and his team have found.

"We saw a ring of chlorophyl in southern Lake Michigan," said Kerfoot.

That was the first surprise. Something like chlorophyl is supposed to be evenly mixed in the waters of the lake. But in the late 1990s the Michigan tech team, and numerous other researchers and agencies, used boats and mini-submarines, and sophisticated buoys and even satellite imagery, to prove that a kind of doughnut exists in southern Lake Michigan. The round swirl is a merry-go-round of phytoplankton and zooplankton, the basic building block of life in the lake. The doughnut is kicked up by winter storms and it swirls around a low spot in the lake. That was surprising enough, but there was more.

"Then came the quagga mussels. We picked them up near the end of the project in 2001," said Dr. Kerfoot.

Think of the quagga as a cousin of the more famous zebra mussel. They probably arrived in the ballast water of foreign ships. The quagga now lives in the soft bottom of the Lake Michigan. Five years ago a one-square meter soil sample of lake bottom contained dozens of them. But more recent samples show as many as 15,000 per square meter.

Quaggas are multiplying very rapidly, and they are eating the doughnut.

"They eat all the building blocks out of that water column. They are sucking down all the particulate matter, and that includes the chlorophyl. So the primary producers are being literally sucked out of the lake down to the quagga layer," said Dr. Kerfoot.

Starting in April of 2001 when researchers first found the quagga, they found an abundance of chlorophyl, phytoplankton and zooplankton. But by 2008, they found the doughnut had been eaten away.

Further evidence is how clear the water has become in southern Lake Michigan. Kerfoot estimates the quagga are already consuming four to seven times more of the basic food building blocks than the lake can produce. He fears the lake is losing the battle.

"There's something wrong when you get water as clear as your bathtub water. There's nothing living in it. What is happening is a collapse of the food chain," said Dr. Kerfoot.

The research goes on, while Dr. Kerfoot and the Michigan tech team wonder why no one else seems to hear the alarm. He says research on how to control the Quagga is desperately needed but he doesn't know of anyone who is doing it.

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