GLEAM

Great Lakes Environmental Assessment and Mapping Project

Great Lakes Stressors

Cumulative stress to the Laurentian Great Lakes is determined from 34 individual stressors, along with habitat and lake-specific weights derived from an extensive survey of Great Lakes researchers. A stressor is defined in this project as a pressure, which exceeds its range of normal variation due to human activity, affecting species, biological communities, or ecosystems.

Great Lakes stressors were divided into seven categories:

  • 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