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AbstractFour river systems on the Wisconsin shoreline of Lake Michigan are designated Areas of Concern (AOCs) because of severe environmental degradation: the Lower Menominee River, Lower Green Bay and Fox River, Sheboygan River, and Milwaukee Estuary. Each AOC has one or more Beneficial Use Impairments (BUIs) that form the basis of the AOC designation and that must be remediated or otherwise addressed before the AOC designation can be removed. All four of these AOCs have BUIs for benthos (bottom-dwelling or benthic invertebrates), and all but the Menominee River have a BUI for plankton (free-floating algae and invertebrates, or phytoplankton and zooplankton, respectively). The U.S. Geological Survey collected samples in 2012 at these four AOCs and at six non-AOCs to support the evaluation of the status of aquatic communities in the benthos and plankton at the AOCs. Samples were collected during three periods representing spring, summer, and fall. Benthos samples were collected using a dredge grab sampler and artificial substrates; plankton samples were collected using a tow net for zooplankton and a vertical water sampler for phytoplankton. Benthos and plankton were identified to the lowest possible taxonomic category and counted; samples for documenting water temperature, pH, and specific conductance, as well as sediment particle size and organic carbon were also collected during biological sampling.
IntroductionThe Laurentian Great Lakes of the United States and Canada contain one-fifth of all the freshwater in the world. They face common plights of many large water bodies, such as invasive species, native species loss, nutrient enrichment, chemical contamination, habitat degradation, bank erosion, and sedimentation. Within the Great Lakes, certain geographic areas are considered to have severe environmental degradation and were defined as Areas of Concern (AOCs) in the United States-Canada Great Lakes Water Quality Agreement (International Joint Commission United States and Canada, 1987). Along the Great Lakes shoreline, 43 AOCs have been identified: 26 in U.S. waters and 17 in Canadian waters, and five AOCs are shared between the nations. Four AOCs in Wisconsin are along Lake Michigan's shoreline: the Lower Menominee River, Fox River and Lower Green Bay, She...
