Invasive Species

Invasive Species

  • Nonnative species that have successfully invaded (or are likely to invade) an ecosystem, causing significant ecological, economic, or human health problems

  • Non-native and invasive are not mutually exclusive


Is it REALLY Invasive?

  • Sea lampreys are considered an invasive species in the Great Lakes, BUT genetic analysis suggests they’re native to Lake Cxzxhamplain (colonized the lake postglacially)


How do they get here?

  • European colonization

  • Agriculture, horticulture, aquaculture

  • Accidental transport (e.g., ballast water)

  • Biological control


Impacts of Invasive Species

  • Introduced predators

  • Introduced competitors

  • Morphological & behavioral impacts


Genetic Impacts

  • Hybridization 

    • Genetic swamping


Biological Characteristics of Introduced Fishes in the Great Lakes

  • Fast growth rate

  • Wide temperature tolerance

  • Wide salinity tolerance

  • Small egg size


Successful Invaders 

  • “Tens Rule”

    • 1 in 10 transported species escape into the wild

    • 1 in 10 escaped species become established

    • 1 in 10 established species become invasive

  • Invader characteristics

    • Early-successional colonizers

    • Abundant

    • Tolerant of a wide range of conditions with high reproductive potential

    • European

    • Enemy release hypothesis

  • Ecosystem characteristics

    • Islands

    • Disturbed

    • Biotic resistance hypothesis


Control of Invasive Species

  • Restrictions on transport

  • Eradication

  • Biological control