Alien algae alarms aquatic experts

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Capital News Service

Credit: New York Sea Grant

LANSING—An invasive species of algae is threatening to disrupt the ecological balance in Michigan lakes and waterways.
It’s a form of seaweed called starry stonewort.
“Starry stonewort can change the ecology of lakes. It lowers the reproduction of fish species and ruins the habitats needed for fish and aquatic insects,” said Gary Crawford, senior fisheries biologist consultant at Environmental Counseling & Technology Inc. in Ann Arbor.
It can also increase the potential for winterkill when lakes freeze over because the algae take up oxygen that fish need to survive.
R. Jan Stevenson, professor of zoology at Michigan State University, said it’s not the kind of algae that commonly grows in the area lakes and its source is unknown.
Starry stonewort was first found inland in Lobdell Lake in Genesee County’s Argentine Township in 2006 and has been spreading since then, crowding out other underwater plants, said Frank Ruswick, deputy director of the Department of Natural Resources and Environment (DNRE).
Crawford said the plant has hit more than 90 inland lakes, primarily in Southeast and Southwest Michigan, the Upper Peninsula, the northern Lower Peninsula and Indiana.
The starry stonewort is an early ancestor of plants. It lives in fresh water and can tolerate low nutrient and light levels, according to Stevenson. Starry stonewort can be found at three to 20 feet deep in lakes or slow-moving rivers, he said.
In addition, the algae are spreading along the northern coast of Lake Michigan, and Crawford said it’s beginning to move closer to shore.
Fish also have a harder time surviving because of the thick weeds of the starry stoneworts, he added.
Compared to fast-moving invasive species such as the zebra mussel, it has taken the starry stonewort nearly 30 years to become conspicuous in Michigan inland lakes, Crawford said.
Starry stonewort moves rapidly from lake to lake and is easily transported in aquatic plant debris that may be caught on boat trailers, he said.
Crawford said one option to stop them is raking but it is labor-intensive and can cause fragmentation, which allows the algae to develop faster.
Other options include chemical treatment and increasing water movement, he said.
Crawford is a member of a task force focusing on aquatic invasive species. Other members are from the University of Michigan, Grand Valley State University and the DNRE. They are looking for the best way to stop the problem.
© 2010, Capital News Service, Michigan State University School of Journalism. Not to be reproduced without permission.

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