Published March 22, 2021 at 1:11 PM EDT Listen • 5:02
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John Janssen remembers the moment he realized Lake Michigan was about to change.
It was a September day in 1990 and he was diving looking for sculpin an ugly fish with big lips that likes to hide under rocks.
“I wasn’t paying much attention to anything else it was my dive partner who suddenly grabbed me and pointed out that first zebra mussel,” he says.
“I just lay on the bottom for like five minutes, trying to imagine what the lake was going to look like in a year.”
Janssen is a fisheries biologist at the University of Wisconsin, Milwaukee, and he knew what was coming. Zebra mussels had already invaded Lake Erie.
Invasive quagga mussels have changed the chemistry of the Great Lakes, churning up phosphorus that feeds algae blooms. They also damage ships and clog water-treatment pipes.
Quagga mussels have taken over four of the North American Great Lakes to such an extent that in many places they have completely taken over every available underwater surface so there is little room for anything else. Image Credit: Swenson College of Science and Engineering
North America’s Great Lakes are by far the largest connected freshwater system in the world. In a little over 30 years their biology has been utterly changed with the establishment of invasive populations of zebra and quagga mussels, with an immense decline in the abundance of native plants and animals. A new study shows the quagga mussels have taken over the cycling of the lake’s stores of phosphorus, one of the few elements essential to almost all life. The authors warn many European lakes could be headed for similar declines now the mussels are spreading there, and offer some ideas of how to control the invader.
January 26, 2021
The health of aquatic ecosystems depends on the supply of key nutrients, especially phosphorus. Too much phosphorus results in unwanted eutrophication, and much effort is spent on preventing phosphorus pollution of water bodies. In the world’s largest freshwater ecosystem, the North American Great Lakes, this control may have recently been lost to an invasive species.
According to a new study published in the journal PNAS, quagga mussels, which have spread across four of the five Great Lakes, have accumulated large amounts of phosphorus in their biomass, to the degree that their activities now regulate the supply of phosphorus to the ecosystem.