Mapping Environmental Stessors on the Great Lakes
Posted on: May 15, 2017
Environmental stress mapped across the surface of the Great Lakes. This map is a closer look at the cumulative influence of 34 different environmental threats on Western Lake Superior. The colours represent stress levels compared to other parts of the five lakes. (Image: University of Michigan)

It should be no surprise that the Great Lakes face immense environmental pressures. During the 1960s, Lake Erie was pronounced “dead” due to overloading of phosphorous from municipal waste.

The Great Lakes Environmental Assessment and Mapping Project — a group of about 20 American and Canadian researchers and environmentalists — produced the data for this map, which illustrates the cumulative impacts of human activity across the Great Lakes. It speaks volumes at a glance. David Allan, team lead for GLEAM’s project and a professor at the University of Michigan’s School of Natural Resources and Environment, hopes the map will help improve how we manage the Great Lakes.

For three years, GLEAM’s scientists analyzed, weighted, plotted and merged 34 environmental stressors, including various effects of residential, commercial and industrial development, crisscrossing shipping lanes, thriving invasive species (in many areas, zebra and quagga mussels are a more serious problem than pollution) and climate change.

“The red spots on this map are not all red for the same reasons,” says Allan. “Our goal is to help people understand that there are many complex combinations of stressors at play here and that they have a spatial pattern. We have to resist the temptation to say, ‘What’s the most important thing? Let’s fix that.’ ”

The list of 34 individual stressors on the Great Lakes were divided into seven categories with specific maps available for each stressor.

MAPS FOR EACH INDIVIDUAL STRESSOR:

  • Aquatic habitat alterations: Changes to aquatic habitat from diverse causes, such as shoreline hardening and erosion control structures, port and marina development, and tributary dams
  • Climate change: Changes to seasonal, average, and extreme temperature, precipitation, and ice cover
  • Coastal development: Land-based human development near lake margins, such as residential and commercial development and industrial activities
  • Fisheries management: Changes to Great Lakes ecosystems resulting from fishing pressure, stocking activities, and aquaculture
  • Invasive species: Changes to Great Lakes ecosystems from invasive and nuisance species in abundances not previously seen
  • Nonpoint source pollution: Nutrients, sediments, and waterborne contaminants transported from watersheds to the Great Lakes by streams and rivers and atmospheric deposition
  • Toxic chemical pollution: Chemical pollutants from industrial and agricultural sources.

 

 

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