Invasion
Invasion Description
1st Record: mid-lake reef complex, off Milwaulkee/WI/Lake Michigan (Cuhel and Aguilar 2013)
Geographic Extent
mid-lake reef complex, off Milwaulkee/WI/Lake Michigan (Cuhel and Aguilar 2013); off Racine/WI/ Michigan (2003, USGS Nonindigenous Aquatic Species Program 2008)
Vectors
| Level | Vector |
|---|---|
| Alternate | Hull Fouling |
| Alternate | Ballast Water |
Regional Impacts
| Ecological Impact | Competition | |
| Quagga Mussels developed populations in deeper waters around offshore reefs in Lake Michigan, and kept filtering through the winter at low temperatures. This filtering lowered phytoplankton concentration in spring, when Zebra Mussels, which are dormant in winter, began to start feeding again. The difference in the seasonality of feeding led to the complete replacement of Zebra Mussels by Quagga Mussels on offshore reefs (Cuhel and Aguilar 2013). | ||
| Ecological Impact | Habitat Change | |
| Heavy settlement of Quagga Mussels around offshore reefs in Lake Michigan, led to increased structure and sedimentation on rocky surfaces, and limited scouring of sediments. On level, soft silt/clay sediments, dense colonies of mussels created new, complex structure. The large filtering biomass led to increased water clarity, and increased depth of algal growth, dimnishing spawning habitat for Lake Trout (Salvelinus namaycus), which prefer to spawn in darkness, on bare cobble bottoms (Cuhel and Aguilar 2013). | ||
| Ecological Impact | Trophic Cascade | |
| Heavy grazing of phytoplankton, and reduction of settlement, diminshed food for the previously abundant deposit-feeding amphipod Diporeia hoyi, a major food item of Lake Whitefish (Coregonus clupeiformis) and Cisco (Coregonus spp). Because of the year-round decrease in phytoplankton biomass, the biomass of zooplankton is expected to decrease, in turn decreasing the abundance of forage fishes (Cuhel and Aguilar 2013). | ||