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.