MODULE 2

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MODULE 2

• Impacts of IAS

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Learning Outcomes

• By the end of this module you should be able to
• understand the different types of impacts
• know the costs associated with IAS
• give examples of problematic species
• identify the indirect effects of IAS

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Categories of IAS impacts

• Economic
• Environmental
• Social

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Economic impacts

• In the US the economic costs of invasive plants
  and animals are estimated at US137 billion per
  year.

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Economic impacts

• These include
• Primary production
• Trade
• Infrastructure damage
• Management
• Other sectors

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Primary production

• Agriculture
• up to 40 of global agricultural production lost
  due to IAS
• up to 49 of production in Africa

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Primary production

• Leafy spurge
• competes with native plants
• increases erosion
• toxic to animals
• causes skin irritation

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Primary production

• European rabbit
• annual cost to Australias agricultural
  production is US373 million
• feeds on many crops, including wheat and
  livestock forage
• causes erosion

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Primary Production

• Field rat
• Feeds on harvested grain and destroys crops
• In Indonesia consumes 17 of rice crop

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Forestry

• IAS impacts include
• timber losses
• cost of herbicides and pesticides
• worldwide cost of 100 billion per year

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Primary Production

• European gypsy moth
• causes extensive defoliation
• eats the leaves of approximately 500 plants and
  trees
• a major pest in North American forests

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Primary Production

• Comb jelly
• comprises up to 95 of the biomass in the Black
  Sea
• was responsible for the collapse of the anchovy
  fishery, which was worth US 250 million/year

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Primary Production

• Sea lamprey
• predate upon sport fish in the Great Lakes of
  North America
• extract blood and fluids from host fish

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Trade

• Export restrictions for IAS infested countries
• Hawaii
• loss of millions of dollars in fruit exports when
  fruit flies discovered

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Tourism

• Siam weed (Chromolaena odorata)
• a threat to conservation and ecotourism
• invades natural areas
• reduces biodiversity
• compromises game-viewing in nature reserves and
  national parks

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Tourism

• SARS outbreak
• caused 17 billion loss to Chinas tourism
  industry in 2003

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Property / Infrastructure

• Brown Tree Snake
• causes US 1-4 million damage to power lines on
  Guam
• power outages every 3 days on average

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Property / Infrastructure

• Zebra mussel
• clogs water intakes and discharge pipes
• competes with native mussels
• cost of control is US 10 billion over 10 years

Fouled pipe
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Property / Infrastructure

• Formosan subterranean termite
• infestations weaken the structure of houses
• cause US1 billion/year of damage in the United
  States

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IAS Management

• Globally, billions of dollars are spent to
  prevent, eradicate and control IAS impacts
• Although the costs of prevention are often high,
  they are minor compared to the costs if an IAS
  were to become established

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Social Impacts

• Human health
• introduced infectious diseases can have a
  devastating impact
• AIDS, smallpox, cholera

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Social Impacts

• Recreation
• invasive plants interfere with recreational
  activities in parks and protected areas

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Culture

• Invasive species can impact on the cultural
  values and activities of an area
• Examples

- loss of native grasses used in basket making -
the loss of species harvested for ritual
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Livelihoods

• Loss of biodiversity due to IAS affects peoples
  livelihoods

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Environmental Impacts

• Ecosystems and biodiversity
• within an ecosystem all species are connected
• a disruption to one species can affect a whole
  range of other species

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Species level impacts

• IAS can affect native species by
• changing their abundance
• changing their geographical range
• causing local or global extinction

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Ecosystem level impacts

• IAS can change the balance and structure of
  ecosystem
• common wasps have invaded New Zealand beech
  forests
• they monopolize high-energy honeydew produced by
  scale insects
• native species are unable to
• feed on this important resource

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Processes

• Predation
• Herbivory
• Disease (pathogens)

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Processes

• Physical processes (fire regimes, nitrogen
  cycles)
• Competition
• Hybridisation
• Parasitism

The mallard duck hybridises with many native duck
species
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Concluding remarks

• Many IAS are detrimental to the economy as well
  as human health and the environment
• Unlike other environmental pollutants IAS have
  an increasing impact over time

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Summary

• Invasive Alien Species have had enormous negative
  impacts.
• IAS are found in nearly every habitat and occur
  in all major taxonomic groups.
• Invasive species can have adverse economic,
  social and ecological impacts.
• Billions of dollars are spent annually to
  prevent, control and manage IAS.
• The introduction of an IAS can cause major
  ecosystem changes.