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Developed by Dr. Hongyan Zhang (University of Michigan), Edward Rutherford (NOAA Great Lakes Environmental Research Laboratory), and Yu-Chun Kao (USGS Great Lakes Laboratory)


The purpose of the model is to examine the impact of increased nutrient loads on the food web of Saginaw Bay. Users can view changes in the biomass of walleye, yellow perch, aquatic plants, and harmful blue-green algae in the Bay when Phosphorus (P) concentration is increased or decreased. At a certain point, increased P causes a decrease in the biomass of yellow perch and aquatic plants, while the biomass of blue-green algae and walleyes will continue to increase.


  • Select P concentrations in Saginaw Bay to visualize changes in biomass of walleyes, yellow perch, aquatic plants, and blue-green algae on Tipping Point gauges
  • Save and print maps and data for planning and decision making

Note: Data for this model are only available for certain HUC 12 watersheds within Saginaw Bay (MI).

About the Model (8:17)

Additional Information


  1. Kao, Y., Adlerstein, S., & Rutherford, E. (2014). The relative impacts of nutrient loads and invasive species on a Great Lakes food web: An Ecopath with Ecosim analysis. Journal of Great Lakes Research, 40, 35-52. doi:10.1016/j.jglr.2014.01.010

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