Invasive species Flashcards
(13 cards)
What is an invasive species?
A non-native organism introduced to an environment where it doesn’t naturally occur, as a result of human activity
Its presence can/does harm the environment, economy and human health
What is an introduced species?
A species that lives outside of its native distributional range and has arrived there as a result of human activity
What makes a species invasive?
Fast growth and rapid reproduction (floating pennywort, Himalayan balsam)
Association with a human environment (Japanese knot weed)
Often generalist, can compete with resources, adapt fast and well to a wide range of conditions (Brown rat, lion fish, german cockroach)
Why do invasive species do well?
Good competitors (rhododendron)
No competition in new area (brown tree snake in Guam)
Utilises resources unavailable for other species (European green crab)
Lack of natural predators
Lack of parasites in the new habitat
Or new parasites and pathogens that are harmful to local species (grey squirrel)
Prediction of successful invasions
If a species has successfully invaded one area, it’s more likely to invade others (Drosophila suzukii)
Direct impacts/biotic interactions
Novel prey/mutualist/predator/competitor
Ecological impacts - reduction of biodiversity
Alteration of habitats and ecosystems (rabbits or Cane toad in Aus)
Ecological impacts - other processes
Hybridisation with a native species (mallard duck with New Zealand grey duck and Hawaiian duck)
Invasive species as a driver of speciation
Lupines in Iceland - soil is poor quality and lupines are legumes so enrich nitrogen content in the soil
Agriculture and economic impacts
Crop loss up to 100% in unmanaged fields
Annual control costs $500 mill in US and Europe
Colorado potato beetle
Domestic cats cause around $52 billion in economic costs annually
Human health impacts - disease vectors
Asian tiger mosquito causes zika virus, dengue and yellow fever
Pathways through which invasive species are introduced
Human-facilitated introductions through international trade (ballast water + zebra muscles)
Accidental release (lionfish in Caribbean)
Intentional introduction of water primrose, Japanese knotweed, rhododendron and American skunk cabbage were all introduced as ornamental plants
Intentionally introduced as biocontrol (Cane toad in Aus or mongoose in Caribbean and Hawaii)
Stages of invasive species management
Prevention - control of vectors and pathways (Asian hornet or Colorado potato beetle)
Eradication - measures of eradication might be successful
Containment - prevention of further spread, public awareness typically begins (Asian Carp)
Long-term management - minimise the impact of the invader, protection of native species and resources (Japanese knotweed, giant-African snail)
Control strategies for managing invasive species
Strict border controls and quarantine
Pathway management
Public awareness and education
Legislation and policy
Risk assessment and screening
Clean equipment and vehicles
Early detection and rapid response
Control measures include chemical, mechanical and biological
Integrated Pest Management (IPM) - combining multiple control methods for more effective eradication
What factors facilitate invasions?
Climate change
Land use change
Habitat fragmentation
Human transport and trade
Native species similarity
