Microphotograph of the cladoceran, Daphnia.

Water flea, Bythotrephes cederstroemii. Photo taken by J. Liebig, NOAA GLERL.

Zebra mussels attached to stick. Photo taken by S. van Mechelen, University of Amsterdam, 1990.

Microcystis bloom at the Lake Michigan Field Station, Muskegon, MI, August 2006. Photo courtesy of Greg Marks.

Microcystis bloom in Lake Michigan at the Lake Michigan Field Station, August 2006. Photo courtesy of Greg Marks.

Zebra mussel filtering, showing open siphon. Photo taken by W. Brusate, Marine City, MI, 1995.

Microcystis in container scooped up from Maumee Bay, Lake Erie. Photo taken by D. Schloesser, USGS, Great Lakes Science Center, September 1998.

Close-up of Microcystis bluegreen algae. Maumee Bay, Lake Erie, September 1998. Photo taken by D. Schloesser, USGS, Great Lakes Science Center, late September 1998.

Quagga mussel collected from Lake Michigan, June 2007. Photo by M. Quigley, GLERL.

Zebra mussel (Dreissena polymorpha) collected from Huron River in Ann Arbor, MI. Photo by M. Quigley, GLERL, June 2007.

Hemimysis anomala. Microphotograph by S. Pothoven, GLERL, December 2006.

Hemimysis anomala. Microphotograph by S. Pothoven, GLERL, December 2006.

Hemimysis anomala. Microphotograph by S. Pothoven, GLERL, December 2006.

Hemimysis anomala. Microphotograph by S. Pothoven, GLERL, December 2006.

Hemimysis anomala. Microphotograph by S. Pothoven, GLERL, December 2006.