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MSU Researchers Find Relationship Between Invasive Zebra Mussels With Toxic Algae

Zebra mussels covering a larger shell
Randy Westbrooks/ Invasive Plant Control Inc.
Zebra mussels have be present in Gull Lake since the mid-1990s.

Michigan State University researchers say they have found a connection between invasive zebra mussels and toxic algae blooms through a long-term study.

Scientists from the W.K. Kellogg Biological Station first noticed an invasive population of zebra mussels in Gull Lake in the mid-1990s. Afterwards, unexpected harmful algal blooms started appearing.

That led to a research project to see if there was a connection. Stephen Hamilton is a professor at the station.

dock on lack with sectioned off openings to the water for field testing
Credit Orlando Sarnelle
Researchers did a variety of tests to prove the relationship between zebra mussels and Microcystis.

He says the presence of zebra mussels led to an increase in a type of bacteria called Microcystis that produces the algae.

“The strongest effect is probably a kind of differential feeding where they graze down all the other kinds of algae. And then Microcystis is not palatable and prospers because it’s not competing with these other algae," he said.

In other words, while the mussels feed on all other algae, it leaves Microcystis to prosper in a situation where otherwise it wouldn’t be very competitive.

Hamilton says they also noticed the two species’ connection when a large number of mussels died off due to warm temperatures in 2010.

Warm water usually means more Microcystis.

Instead, researchers saw an 80% decrease of the bacteria.

“Which enabled us to have yet another line of evidence showing the relationship between zebra mussels and Microcystis," he said. "Because that year when they died back, the Microcystis dropped, and then it came back when the zebra mussels came back.”

Hamilton’s team has been studying the interactions between zebra mussels and Microcystis for more than a decade.

McKoy's story is brought to you as part of a partnership between WKAR and Michigan State University's Knight Center for Environmental Journalism.

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