What are invasive species?
• Exotic species
• Naturalized species
• Invasive species
Exotic
Species
• Exotic in the vernacular means
strange, unusual, unfamiliar
Exotic Dancer
Exotic
carrot
Exotic Species Definition
• Exotic Species
• (Alien, non-indigenous,
non-native )
• Introduced New Area
– Outside historic
geographic range
• Different Continent
• Different part of the
same continent
– Different ecosystem
Different continent
House Sparrow
Distribution North &
Central America
Different Part of a Continent
House
Finch
Historic Range SW USA
Introduced
Long Island NY
Different Part of Continent &
Different Ecosystem
Rainbow Trout
Native to tributaries of Pacific Ocean in Asia & North America
Naturalized
Species
Dandelion
• Naturalized species:
– alien (Exotic) species
– establish viable
populations
Chicory –
common
along
roadsides
Ring-necked Pheasant
Naturalized Species
• How many naturalized species occur in
the United States?
• What percentage of Illinois’ Flowering
plants are naturalized?
– Total flora = 3,100 species
– 26% (811 species are naturalized)
Why worry about
alien species?
• There are about
30,000 alien species
in the United States
and most of them are
beneficial
Toby
Why worry about Exotic (Alien)
species?
• Value of Exotic species:
– Produce 98% of USA food supply
– 500 billion dollars
• Some exotic species become invasive
Invasive Species
• Federal Definition –
– “Invasive species” means an alien species whose
introduction does or is likely to cause economic or
environmental harm or harm to human health.
Executive Order 13112 (Feb. 3, 1999)
• 0.1% percent of alien species that arrive become
invasive (10 percent rule)
– 10 percent establish (10%) – they are naturalized
– 10 percent spread (1%)
– 10 percent become invasive (0.1%)
Cost of Invasive species:
• Invasive species cause economic
damage:
– $123- $137 billion dollar annually in USA
• Agricultural pests – about ¼ of agricultural
GNP is lost
• Costs excludes damage to natural
ecosystems
How do invasive species cause
damage
• Invasive species cause damage by:
– Eliminating indigenous species
– Disrupting ecosystem processes
– Reducing biodiversity
– Cause human health or economic
problems
Why are invasive species successful?
• Release from enemies
– Natural competitions, parasites, pathogens, predators
• Increased competitive abilities (ICA)
• “Vacant niches,” unutilized, or under utilized
resources
• Community characteristics
– Species richness
– Disturbance favors invading species
• Native species often have no natural immunity to
introduced diseases –
– Dutch elm disease,
– Chestnut blight
Novel
Native
Ave. Number of Pathogen Species
Fungi
Viruses
Examples of Invasive Species
• Kudzu
• Zebra mussel
• Asian Carp
•Introduced from Japan
•Erosion control & Forage
•Rapid growth
•U.S. Soil Conservation
Service (1935-1942)
Kudzu
Kudzu over grows trees in SE United States
Occupies 7 million acres
Illinois 16 colonies
440 acres
Alaska
Hawaii
Puerto Rico
Virgin Islands
Kudzu Distribution
in USA
Actual size ¾ inch
Zebra Mussel
• Native to streams
– (Ural & Volga) entering Caspian sea
• Great Lakes 1988 – ballast water
• June 1991 first confirmed sighting in
Illinois River
• How did it get into the Illinois River?
Chicago River
Des Plaines
Calumet Slag
Canal
Illinois Sanitary and Ship Canal
• 1800’s Chicago sewage discharge
– Chicago River
– Lake Michigan
• Lake Michigan as a drinking water source
– 1854 cholera epidemic killed 5.5%
– 1860-1900 65/100,000 died annually from
typhoid fever
• Reversed flow of Chicago River (1900)
• Sewage into Des Plaines and Illinois rivers
Chicago River
Des Plaines
Calumet Slag
Canal
After 1900
Zebra mussel Impacts
• Reduced or eliminated native mussels
• Decimated food supply of fish
– Filter out large phytoplankton
– Only metabolize green algae –
• Bluegreen algae (Cyanobacteria)
– Abundance of zooplankton & plankton eating
fish decreased
• Water is clearer
• Economic costs
• – Clogged pipes
– Attach to boats
• Consumed by some ducks & fish
– Not controlled
Transported:
bilge water
and on
exterior of
boats
How do invasive species get here?
• Inadvertently: Foreign transport of goods
– Zebra mussel
– Asian long-horn beetle
– Sea lamprey into Great Lakes
– Asian Tiger mosquitoes
– Brown tree snake
– Dutch elm disease.
• Promoted by state or federal agencies
(kudzu, multiflora rose, autumn olive)