Quagga Mussels Choking Lake Michigan

The ecology of Lake Michigan is slowly being transformed by trillions of quagga mussels, says the National Oceanic and Atmospheric Administration (NOAA). The tiny bivalves, a deep-water loving cousin of the zebra mussel, are dramatically altering the food chain of the lake by trapping millions of pounds of biomass on the lake bottom.

A soon to be released report by NOAA scientist Tom Nelepa and others is quantifying this dramatic change in lake ecology.

Analyzing ten years of data, Nelepa found that the invasive quagga mussel has almost completely displaced a native shrimp-like species of amphipod in some regions. This shrimp species is a major source of food for the lake’s native fish populations.

“They [the quagga mussels] are basically stripping the water of all the phytoplankton and the other invertebrates that rely on the phytoplankton are now starving — their numbers are going down,” Nelepa told Circle of Blue.

As the quagga mussels filter phytoplankton and other micronutrients out of the water, they disrupt the natural flow of energy from these lower organisms to the larger sporting fish – essentially cutting off the energy need for aquatic life in the lake.

The report will be published in the journal of Freshwater Biology in the spring of ‘09.

Inset photo courtesy of NOAA