BIOS104 Invasive species

What is an invasive species?

A non-native organism introduced as a result of human activity to an environment where it doesn’t naturally occur, and whose presence causes- or is most likely to cause - harm to the environment, economy or human health

What is an introduced species?

A species that lives outside its native distributional range and has arrived there as a result of human activity

What makes a species invasive?

• Fast growth and rapid reproduction

• Good at living in human-altered environments

• Generalists - can adapt fast and well to a wide range of conditions

What are some examples of fast growing invasive species?

• floating pennywort

• Himalayan balsam

• Zebra mussels

What are some examples of invasive species good at living with humans?

• Japanese knotweed

• Argentine ant

• Giant hogweed

What are some examples of generalist invasive species?

• brown rat

• lionfish

• German cockroach

Why are invasive species doing well?

• Good competitors (rhododendron)

• No competition in a new area (brown tree snake)

• Utilise resources unavailable for local species (european green crab)

• Lack natural predators (deer)

• Lack parasites in a new habitat or spread new parasites harmful to local species

What can we predict of a species that has successfully invaded one area?

Its likely to invade others

How many invasive species are there in the UK?

More than 2,000

What are the ecological impacts of invasive species?

• reduction of biodiversity (brown tree snake)

• alteration of habitats and ecosystems (rabbits in australia, cane toads)

• Hybridisation with native species (ducks)

• invasive species as drivers of speciation

What is an example of invasive species having both good and bad ecological impacts?

Lupines in Iceland

• Attract nitrogen to the soil so the soil is enriched

• However, no room for anything else to grow

What are the economic impacts of invasive species?

• agriculture (crop loss)

• Wildlife (cats cause $52 billion in economic costs annually)

How can invasive species impact human health?

Through diseases vectors

e.g. asian tiger mosquito

• Dengue fever

• Zika virus

• Chikungunya

• Yellow fever

What are the pathways of invasion of invasive species?

• international trade - shipping & cargo and freight (Zebra mussels & brown tree snake)

• Human-facilitated introduction - accidental release (lionfish, pythons)

• Intentional (victorians and ornamental plants)

• Intentional - biocontrol

What are the stages of invasion?

• Before

• Lag time - few populations, localised

• Expansion - strong growth, rapid dispersal

• Persistence - widespread and abundant, fully established

What are the stages of management of invasive species?

• Prevention - control of vectors

• Eradication

• Containment - Prevent further spread, public awareness

• Long-term management - minimise impact

What are the control measures for early prevention?

• Strict border controls and quarantine

• Pathway management

• Public awareness and education

• Legislation and policy

• Risk assessment and screening

• Clean equipment and vehicles

What are the types of control measures?

• mechanical - hunt or pulling up plants

• Chemical - pesticides

• Biological control - bring other species to predate invasive one

What is integrated pest management?

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