Term
| What are introduced species? |
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Definition
| A species that has been introduced to a location outside its natural distribution by the activities of humans. |
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Term
| What can dispersal be limited by? |
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Definition
Terrestrial: seas, livers, mountains, desert
Marine: Continents, currents, climatic differences, oceans. |
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Term
| How big is the problem of introduced species? |
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Definition
since 1600 intoduced species have facilitated in the extinction of:
20% mammal extinctions
22% bird extinctions
42% reptile extinctions
30% of fish extinctions |
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Term
| Why are some species intentionally released? |
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Definition
- Human colonisers and domestic animals
- Sailors leaving food on islands
- European settlers releasing animals to make it like home
- Biological control
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Term
| In what situations can species escape? |
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Definition
- Crops, forestry plantations, ornamentals
- Aquaculture
- Fur farming
- Game
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Term
| How can species accidentally be introduced? |
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Definition
- Cargo stowaways
- Burrs and seeds in mud
- Ship's ballast
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Term
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Definition
Natural range: S US to S America
Introduced to: Australia
Introduced how? Purposely to eat Cane beetles, whose larvae eat the roots of sugar cane and ruin crops
3000 released in plantations in 1935.
Rate: Moving at 50km/year.
Success: eat anything that fits in their mouth and venomous to predators- no predator in aus.
Problems: Decline in quolls and native frogs |
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Term
CASE STUDY
Brown tree snake |
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Definition
Introduced to: Guam (Mariana Islands) with 11 native birds and 5 endemics
Introduced how? Stowaway in millitary cargo in 40/50s
Success: Guam birds lack predator defences
Problems: 9 of 11 birds extinct and has impacts on lizzards |
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Term
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Definition
Carlton and Geller (1993)
Sampled ballast from 159 ships in USA from japanese posts
Sampled 0.25% of ballast and found 367 identifiable taxa at all trophic levels. |
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Term
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Definition
Guan + Wiles (1997)
Natural range: N America
Introduced to: UK (great buckinghamshire) 1976
Introduced how? Aquaculture
Problems caused: Dominant benthic species (bullhead and stone loach) increase in abundance from crayfish release site. Due to predation and competition for shelters. |
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Term
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Definition
- 400 endemic fish species
- British introduced new techniques causing overfishing
- 1960 introduced non-native species to perk up stocks
- Nile perch and Nile tilapia successful
- >250 at risk or extinct
- Overfishing means populations of algae eating fish are dropping- causing eutrophication
- 1990- introduction of water hyacinth chockes breeding grounds.0
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Term
| What are the characteristics of harmful introductions? |
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Definition
- Natural flora or fauna not adapted
- Natural control factors absent
- May not succeed immediately
- May be encouraged by habitat disturbance
- Not all succeed
- May succeed in one location but not another
- Eradication may be difficult or impossible
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Term
CASE STUDY
How introduced species are encouraged by habitat destruction |
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Definition
Harrison (1968)
Progressive degradation of SE Asian forests not only decreases non-flying native mammal mammals, but increases % of introduces species. |
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Term
CASE STUDY
How an introduced species can survive in one place but not another |
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Definition
Amur honeysuckle
Natural range: E Asia
Introducted: Britain 1896 + USA 1900s
Introduced why? Ornamental species
In America it has spread rapidly, thrives in disturbed habitats and high reproductive output. |
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Term
CASE STUDY
Successful eradication of Coypu |
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Definition
Coypu
Natural range: S America
Introduced to: USA, Europe + Japan (UK 1929)
Introduced how? Farmed for fur
Feral populations in E Anglia
Damage crops, water plant communities and bank stability. Eradication used floating cage traps baited with carrots, 1981-1989. |
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Term
CASE STUDY
Successful eradiction of cats |
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Definition
- Cats introduced to islands throughout world, extinct mammals, birds and reptiles. 33 bird sp.
- Successfully eradicated in 48 islands
- 75% small 21% large
- Eradication of uninhabitad sub-Antarctic island took 15 years intense effort
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Term
CASE STUDY
Eradication impossible? |
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Definition
Himalayan balsam
Introduced to: Kew gardens- now in england and wales
Tall (2m), forms dense stands that choke other plants.
Seed pods ejected 7m and can survive for 2 yrs, repidly spread along water ways. |
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Term
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Definition
Introduced to UK in 19th century. Spread rapidly. Damages forestry, orchards, market gardens and crops. Displaces native red squirrel.
- Loss and fragmentation of habitat
- Direct competition
- Squirrel pox virus fatal for red squirrels and grey are carriers.
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Term
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Definition
Native to: W Europe and N Africa
Introduced: 12th century for food and fur
Cause damage to crops
Grazing can be beneficial to grassland, heath and dunes
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Term
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Definition
Native: C+S Europe
Introduced: by romans
Seeds disperse well, seedlings grow rapidly, robust. Can become established in woodlands, grows to fill canopy gaps. Controlled in ancient woodland. |
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