Download IAS Management Options - Invasive Species Specialist Group

MODULE 2
Impacts of IAS
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
Categories of IAS impacts
• Economic
• Environmental
• Social
Economic impacts
• In the US the economic costs of invasive
plants and animals are estimated at US$137
billion per year.
Economic impacts
• These include:
– Primary production
– Trade
– Infrastructure damage
– Management
– Other sectors
Primary production
• Agriculture
– up to 40% of global agricultural production lost
due to IAS
– up to 49% of production in Africa
Primary production
• Leafy spurge
– competes with native plants
– increases erosion
– toxic to animals
– causes skin irritation
Primary production
• European rabbit
– annual cost to Australia’s agricultural
production is US$373 million
– feeds on many crops, including wheat and
livestock forage
– causes erosion
Primary Production
• Field rat
– Feeds on harvested grain and destroys crops
– In Indonesia consumes 17% of rice crop
Forestry
• IAS impacts include:
– timber losses
– cost of herbicides and pesticides
– worldwide cost of $100 billion per year
Primary Production
• European gypsy moth
– causes extensive defoliation
– eats the leaves of approximately 500 plants and
trees
– a major pest in North American forests
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
Primary Production
• Sea lamprey
– predate upon sport fish in the Great Lakes of
North America
– extract blood and fluids from host fish
Trade
• Export restrictions for IAS infested countries
• Hawaii
– loss of millions of dollars in fruit exports when fruit
flies discovered
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
Tourism
• SARS outbreak
– caused $17 billion loss to China’s tourism industry
in 2003
Property / Infrastructure
• Brown Tree Snake
– causes $US 1-4 million damage to power lines on
Guam
– power outages every 3 days on average
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
Property / Infrastructure
• Formosan subterranean termite
– infestations weaken the structure of houses
– cause $US1 billion/year of damage in the United
States
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
Social Impacts
• Human health
– introduced infectious diseases can have a
devastating impact
– AIDS, smallpox, cholera
AIDS ribbon
Smallpox
Cholera
Social Impacts
• Recreation
– invasive plants interfere with recreational activities
in parks and protected areas
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
Livelihoods
• Loss of biodiversity due to IAS affects
peoples’ livelihoods
Mile-a-minute weed overgrowing a fence in Palau
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
Species level impacts
• IAS can affect native species by:
– changing their abundance
– changing their geographical range
– causing local or global extinction
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
Wasp feeding on honeydew
Processes
• Predation
• Herbivory
• Disease (pathogens)
Black petrel killed by feral cat
Processes
• Physical processes (fire regimes, nitrogen
cycles)
• Competition
• Hybridisation
• Parasitism
The mallard duck hybridises with many
native duck species
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
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.