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Human Impacts-Introduced Species

Human Impacts-Introduced Species. What Are They?. Species humans bring to a new ecosystem Can be intentional or unintentional New ecosystem is probably not ready New species can dominate in ecosystem lacking natural predators Outcompete native species in their niche. Stink Bugs.

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Human Impacts-Introduced Species

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  1. Human Impacts-Introduced Species

  2. What Are They? • Species humans bring to a new ecosystem • Can be intentional or unintentional • New ecosystem is probably not ready • New species can dominate in ecosystem lacking natural predators • Outcompete native species in their niche

  3. Stink Bugs • 1988-Introduced to US from East Asia in shipping crates • First seen in Allentown • Pest Insect • Produce Large Populations • Resistant to Pesticides

  4. Stinkbugs (cont’d) • Outcompete native insects who do not resist pesticides • Feed on crops such as cotton, corn, soybeans, and shrubs • No natural predators • Release unpleasant odor when threatened

  5. Zebra Mussels • Native to streams in South Russia • First seen in North America in Great Lakes in 1988 • Have natural enemies in Europe, but not North America • Invasive in North America, Great Britain, Spain, Ireland, and Sweden

  6. Zebra Mussels (cont’d) • Introduced to North America by ocean-going ships • Since introduction, have spread far • Cost to manage in Great Lakes is over $500000 per year • Outcompete native animals for food • Can suffocate other clams and mussels • Possible source for deadly avian botulism

  7. Kudzu • Introduced to US from Japan in 1876 in Centennial Exposition in Philadelphia • Introduced to Southeast shortly thereafter • Marketed as ornamental plant, cow feed, and to prevent oil erosion • When left unattended, it spread quickly and became a weed • Covers 7400000 acres in the US

  8. Kudzu (cont’d) • Native to China where colder climate controls it • Controlled in US through mechanical, biological, and chemical methods • Mechanical: Cutting it back, which is time consuming • Biological: Bacterial blights and insects • Chemical: Herbicides and soil solarization

  9. Cane Toad • Originated in Central and South America • Introduced to Caribbean islands, Pacific islands, and Australia • Australia was particularly susceptible due to its distinct, isolated, ecosystems • Introduced to Australia to control cane beetle; failed • Spread rapidly: 1935-about 100 toads Now-Over 200 million

  10. Cane Toads (cont’d) • Australian predators cannot handle toxin produced by toad • Some predators try to eat them, resulting in less biodiversity for the predator species • Outcompete native species for food

  11. Cane Toad Control Methods • Physically trapping them • Unfortunately, may trap wrong species • Toxins from adults can be used to lure tadpoles

  12. Yellow Star Thistle • Native to Mediterranean basin where it has herbivore enemies and coevolved with other plants • Introduced to California after the Gold Rush • Thrived due to Mediterranean Climate • Human activity helped to distribute plant (i.e. mowing, land grading, soil disturbance) • 5 million acres of it just in California • Does not have many predators in US

  13. Yellow Star Thistle Control Methods • Herbicides • Some insects will eat it • Rust fungus attacks it • Some animals will graze on it

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