Invasive Species

Many non-native species live in the Great Lakes, and some of them are considered invasive. These species have established populations, multiplied rapidly and caused profound and lasting impacts on the Great Lakes ecosystem. Others (such as Asian carp) have caused serious ecological problems in other parts of the country and threaten to enter the Great Lakes. This lesson explores how invasive species have impacted the Great Lakes and how people can help prevent the spread of these unwanted species.

Grade level: 4-8 grades

Performance Expectations:

  • MS-LS2-4 Ecosystems: Interactions, Energy and Dynamics. Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.
  • MS-LS2-2 Ecosystems: Interactions, Energy and Dynamics. Construct an explanation that predicts patterns of interactions among organisms across multiple ecosystems.

For alignment, see: Invasive Species NGSS Summary


  • Name and visually recognize the primary aquatic invasive species of the Great Lakes.
  • Understand and analyze the negative impacts that invasive species have on the Great Lakes ecosystem.
  • Explain the ways in which non-native species are introduced into the Great Lakes.


Many non-native species have been introduced into the Great Lakes since the early 1800s, either accidentally or intentionally. Nonindigenous or non-native species are plants and animals living outside of the area where they evolved. A fraction of these species (about 10%) are considered invasive. Aquatic invasive species are non-native plants, animals and microscopic organisms that have a profound negative impact on an aquatic ecosystem or human activity.

Free from natural predators, invasive species reproduce rapidly in their new homes and compete with native species for food and habitat. They disrupt the aquatic food web by reducing food for native species or by preying directly upon native species. Invasive species are often called “biological pollutants.” They’re costly to manage and have led to a severe loss of biodiversity throughout the world.

In the Great Lakes, zebra and quagga mussels and sea lamprey are among the invasive species that have permanently altered the ecosystem, contributed to declines in native species, and impacted sport and commercial fishing. Invasive plants, such as purple loosestrife and Eurasian watermilfoil, have established themselves in many wetlands and inland lakes, respectively, resulting in a loss of native plants and the wildlife that depend upon them.

Many invasive species in the Great Lakes were transported from foreign ports in the ballast water of ocean-going freighters. Ships often take on ballast water for better balance, stability and safety. Today, the United States and Canada require that most ships entering the Great Lakes exchange their ballast water while still at sea to reduce the transport and introduction of new species. Other species like sea lamprey entered the Great Lakes on their own when shipping canals were modernized. Still other introductions are the result of accidental releases, like when a fisherman is using bait that may not be a native species.

How You Can Help

Prevent the transport of aquatic invasive species. Before leaving a body of water:

  • Remove mud, plants, fish and animals from fishing gear, boats, motors, and trailers.
  • Eliminate water from all equipment, including swimming floats, boat hulls, and bait buckets.
  • Clean and dry anything that came in contact with the water—even boots, clothing, and pets.
  • Do not release or put plants, fish or animals into a body of water unless they came out of it. Dispose of unused fishing bait in the trash.
  • See: Protect Your Waters Website



  • Great Lakes Most Unwanted
    Summary: Students work in small groups to organize invasive species cards, featuring facts and photos. Each group presents a different invasive species in a poster or fact sheet to the class.
    Time: 2 hours