Invasive species

Invasive Species

  • Definition: Non-native organisms introduced to new environments (intentionally or unintentionally) that establish, spread, and cause harm.

  • Types: Can be plants, animals, fungi, or microorganisms.

  • Characteristics: Often thrive in new environments due to a lack of natural predators, pathogens, or competitors.

Threats to Biodiversity and Ecosystems

Impacts of Invasive Species

  1. Ecological Impacts

    • Disruption of ecosystems by outcompeting native species.

    • Reduction of biodiversity and alteration of habitats.

    • Can lead to the extinction of native species.

    • Disruption of natural processes such as pollination and nutrient cycling.

  2. Economic Impacts

    • Severe costs to agriculture, fisheries, forestry, and tourism.

    • Require costly management efforts to control.

    • Can lead to reduced yields and damage to infrastructure, costing billions annually.

  3. Human Health Impacts

    • Direct threats to health by spreading diseases.

    • Triggering allergies or hazardous conditions.

    • Examples include skin irritation from certain plants and disease spread by invasive mosquitoes.

Ways Invasive Species Threaten Biodiversity

1. Outcompeting Native Species

  • Resource Competition:

    • Compete effectively for food, water, and space, e.g., zebra mussels in North American freshwater systems filter out plankton.

  • Rapid Growth and Reproduction:

    • Establish dense populations quickly, pushing native species toward decline or extinction.

2. Predation on Native Species

  • Direct Predation:

    • Invasive species prey on native species with no natural defenses, e.g., the brown tree snake in Guam nearly wipes out bird species.

3. Spread of Diseases

  • Pathogen Carriers:

    • Introduce new diseases; e.g., American grey squirrels carry squirrel pox virus lethal to native red squirrels.

  • Ecosystem-wide Effects:

    • New diseases can lead to die-offs affecting entire ecosystems.

4. Habitat Alteration

  • Changing Physical Landscapes:

    • Some species like kudzu smother native plants, altering habitats.

  • Soil and Water Chemistry:

    • Certain plants, e.g., salt cedar, change soil composition and salinity, making it inhospitable for native species.

5. Hybridization with Native Species

  • Genetic Pollution:

    • Invasive species interbreed with native species, e.g., mallard ducks with black ducks, threatening genetic integrity.

  • Loss of Unique Traits:

    • Hybridization can dilute unique adaptations and traits in native species, compromising their survival.