Invasive mussels don't get a lot of love around the Great Lakes, because they take food from other animals and carpet much of the lake floor.
But Michigan State researchers say quagga mussels may actually doing some good.
"We think that they’re filtering the E. coli out of the lake directly and just kind of acting as predators on the E. coli,” PhD student Chelsea Weiskerger told Michigan Radio.
She and research partner Richard Whitman examined years of records of E.coli pollution at 64 beaches along lakes Michigan and Erie.
Weiskerger says quagga mussels make the water clearer, allowing ultraviolet rays from to sun to reach further underwater.
“And those UV rays, they can come in and they can damage the DNA of things like E. coli and other bacteria," she told MIchigan Radio's Lester Graham. "When that does that, it renders these things either temporarily or permanently inviolable, like inactivated."