Lesson 9 – Invasive or Exotic Species

Non-Native Species Non-native, or exotic, species are those species that do not naturally occur in an ecosystem They arrive in ecosystems in a variety of ways: Boats or travellers from other countries carry organisms unknowingly People bring seeds or cuttings of exotic plants to grow in their gardens Sometimes species are intentionally introduced to help solve a problem

Non-Native Species Introduction of many non-native species fails because few species can tolerate the conditions (temperatures, precipitation, predators, disease) of an entirely new ecosystem Once in a while, a species will thrive due to few predators or disease to limit reproduction The intentional introduction of a species must be carefully monitored to ensure it does not disrupt the existing ecosystem

Invasive Species In some cases, native species might not be able to compete with an introduced species, which will allow the new species to increase quickly and become invasive Invasive species are non-native species that have a negative impact on the natural environment Invasive species populations often grow out of control which can lead to the extinction of native species

Introduction Fail! South America introduced the Canadian beaver in the 1940s for its fur; the fur did not grow thick enough in the warmer climate; beavers were not trapped or hunted and populations exploded causing lots of damage; foxes were introduced to prey on beavers; foxes fed on native rabbits instead; lack of rabbit droppings affected soil conditions and entire ecosystem was out of balance; the beavers have continued to spread and cause damage

Invasive Species in Canada More than 3000 invasive species in Canada More than 185 of those are in the Great Lakes region Invasive species have negative impacts on the ecology, economy, tourism, and health of a region Canada spends millions of dollars each year to control invasive species Damage by invasive species around the world is estimated to cost $1.4 trillion annually

Invasive Species in Canada Zebra mussel 1988 from bilge water Sea lamprey Round Goby Emerald ash borer beetle Asian long-horned beetle Toronto, Vaughn – 27 000 trees removed Purple Loosestrife Kudzu Vine

Controlling Introduced Species Chemical Control – use pesticides to protect trees, crops, fisheries, human health; may pollute or kill native species Mechanical Control – human made barriers to prevent spread; pulling or digging up plants or trapping insects Biological Control – predator or infectious agent is used to kill or harm the species

Keeping Asian Carp out of Great Lakes Escaped into Mississippi River in 1990s during flooding Have made their way north towards the Great Lakes Chicago Ship and Sanitary Canal is the only connection from the Mississippi to the Great Lakes Building a Barrier Asian Carp Fishing