Controlling alien species

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  • Created by: rahza
  • Created on: 27-09-17 03:31

Controlling alien species

Alien or invasive species are those that have moved from one ecosystem to another where they were previously unknown.

Causes:

  • humans trading animals and plants
  • introduced as biological control agents to control pests
  • escapees
  • animals introduced for sport

Effects:

  • become successful predators
  • compete effectively with native organisms of the same niche, pushing them to extinction
  • introduce diseases --> spread to organisms that have been exposed to that pathogen
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Examples:

Water hyacinth: 
grow successfully:

  • covers huge areas of land and water
  •  blocks sunlight from reaching native aquatic plants
  •  reduce concentration of oxygen in the water
  •  kills fish

habitat for mosquito larvae

Japanese knotweed:

  • vigorous root systems --> forces its way through concrete and damaged buildings, roads, walls.
  • Outcompetes native species by reducing space where they grow.
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Examples:

Cane toad:

  • introduced to Queensland, Australia from Hawaii in 1935
  • aim: control insect pest of cane sugar
  • the cane toad bred rapidly, spreading across the country
  • has few predators in Australia as the toad produces a toxing that kills animals that eat it

Red lionfish:

  • native to seas of South-East Asia
  • escapee from the Caribbean
  • becomes a predator in its new environment; eats local species of coral reefs

Indian mongoose:

  • introduced to Jamaica in 1872
  • aim: control rats in cane fields
  • the mongoose did so well it became a predator to other animal
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