Great Lakes: Quagga mussels -spit out Microcystis

Invasion of the Great Lakes: Quagga mussels least known, most dangerous invader

Algal blooms return

Many areas of the Great Lakes have seen a return of blooms of the toxic blue-green alga Microcystis.

"The quagga mussels are filtering out particles in the water, but not Microcystis, which they spit out," said Nalepa. "That leaves Microcystis with fewer competitors for nutrients."

Without the brake of competition, the Microcystis algae proliferate.