3.5: The Introduction of Non-Native Species
pg. 91
Key Concepts:
4. Many human activities impact and threaten the sustainability of natural ecosystems.
Invasive Species: a non-native species whose intentional or accidental introduction
negatively impacts the natural environment.
- When non-native species are introduced to Ontario, most fail because they can not adapt
to their new environment.
- Those non-native species that doe survive are able to tolerate the limits set by the
abiotic environment.
- In some cases the non-native species may not have natural predator (population control),
therefore they may out grow their ecosystem and have a negative effect on both the biotic
and abiotic factors of that ecosystem.
- Non-native species which have a negative effect are called invasive species.
- There are over 3000 invasive specie sin Canada, 185 in the Great lakes alone.
- Invasive species have environment al and economic impacts. They change the natural
ecosystems, and cost billions of dollars to control.
Table 1: Impacts of Invasive Species
Type of
Impact
Ecological
Economic
Tourism
Health
Consequences
- Invasive species compete with or feed on native species, leading to
population decline or extinction.
- Invasive species change ecosystem dynamics by altering nutrient
cycles or energy flow.
- Damage to forests and agricultural crops causes financial losses.
- Competition with invasive plants lowers crop yield.
- Diseases and pests may destroy livestock and crops, kills trees, and
harm important species such as honeybees.
- Species loss and reduced water quality have negative impacts on
wildlife viewing, fishing, and water-based recreation.
- Waterways can become choked with invasive aquatic plants,
rendering them impassable to boats.
- Disease-causing organisms, such as; the West Nile virus, are
introduced.
- Pesticides used to control invasive species cause pollution and are
health risks.
Controlling Introduced Species
- It is difficult to control the introduction of non-native species and the to determine
whether they will become invasive over time.
- There are three types of control measures; chemical, Mechanical, and Biological.
Chemical Control
- Pesticides are used mostly in forests and agriculture because of their economic
importance.
- There risks with pesticides, they sometime target native species also.
Mechanical Control
- Physical barriers or removal is used to control invasive species.
Biological Control
- Biological control is very effective, yet does have its challenges.
- The introduction of other organisms to control the invasive species, may control or
reduce invasive species impact, but may lead to secondary problems.
Science Works: Containing the Invasion
BLM: 3.SW-1
Evidence of Learning: Students can …
- explain why most introduced species fail to survive in a new ecosystem.
- describe what makes an introduced species invasive.
- describe some of the ecological and environmental impacts of invasive species.
- discuss the costs and benefits of different methods of controlling invasive species.
Check Your Learning
Questions 1 – 9, page 94
Summary:
- Invasive species are non-native species whose introduction negatively impacts
ecosystems.
- Invasive species have been introduced intentionally and accidently.
- Invasive species may negatively affect our health and the economy.
- Invasive species can be controlled using mechanical, chemical, or biological methods.