WK 1: Stages of Invasion

Aquatic Biological Invasions FW 421/521

Introduction to Invasive Species

Overview of This Week's Topics

  • Stages of Invasion

    1. Transport

    2. Establishment

    3. Spread

Stages of Invasion

  • 1. Transport

    • Process where species are moved from one location to another, often through human intervention.

    • Possible outcomes:

    • Species may fail in transport which means they do not survive the journey or conditions.

    • Species may survive transport and introduction to a new environment.

  • 2. Establishment

    • The phase where introduced species must establish a population.

    • Criteria for successful establishment:

    • Must survive in the new environment.

    • Must reproduce and form a viable population.

    • Must successfully disperse in the new environment.

    • Outcomes:

    • Non-invasive: Species fails to establish.

    • Invasive: Species successfully establishes.

  • 3. Spread

    • Successful invasive species spread into the new environment beyond the initial point of introduction.

Transport Pathway and Outcomes

  • Graphic representation adapted from Kolar & Lodge (2002):

    • Species can be affected by pathways of transport, which are crucial for determining if they will become invasive or remain noninvasive.

Terminology in Invasion Ecology

  • Alien: Species that are introduced to a new environment outside its native range.

  • Casual: Non-establishing alien species; temporary presence in the environment.

  • Introduced: Any species transported beyond its native range.

  • Naturalized/Established: An introduced species that reproduces consistently and sustains populations in the wild.

  • Invasive: An alien species whose introduction causes or is likely to cause economic or environmental harm or harm to human health.

Framework for Biological Invasions

  • Proposed by Tim M. Blackburn et al. in 2011.

  • Emphasizes the interconnectedness of different invasion stages and how they impact each other.

  • Provides foundational language for discussing invasive species frameworks:

    • Transport: Species that are not transported beyond the limits of their native range.

    • Geography: Consideration of geographical limits concerning invasion potential.

    • Captivity or Cultivation: Impacts of human cultivation on species transport and establishment.

Management of Invasive Species

  • Prevention: Preventing the introduction of potential invasive species.

  • Eradication: Attempting to eliminate invasive populations after they have established.

  • Containment: Preventing the spread of invaders once they are established.

  • Mitigation: Reducing the impact of invasive species on native ecosystems.

  • Concept of 'Boom and Bust': Describes population dynamics of invasive species where rapid population growth can be followed by a sharp decline.

Spatial and Temporal Scale of Invasion

  • Adaptation from Theoharides & Dukes (2007) demonstrates the relationship between the stages of invasion and other ecological processes:

    • Temporal Scale (Years): 10^0 to 10^7, showing the duration for each phase of invasion.

    • Spatial Scale (m²): 10^(-2) to 10^7, indicating the geographical reach of invasive species during different stages (

    • Transport covers small linear distances, whereas spread can cover extensive areas.)

Conclusions

  • Key points on stages of invasion:

    • Transport, Establishment, and Spread are fundamental to understanding the dynamics of invasive species.

    • Importance of identifying human actions that influence the fate of invaders.

    • Recognizing the complexity of the invasion process aids in targeting specific areas for study and management strategies.