Management and Risk Assessment Notes

Management and Risk Assessment

Introduction

This lecture focuses on management issues related to invasive species, especially in the context of risk assessment. As we delve into these topics, it's essential to review how introduced species affect native ecosystems and human economies.

Differentiation Between Explanation and Prediction

Understanding the nuances between explanation and prediction is vital in invasion ecology.

Explanation
  • Retrospective Analysis: In invasion ecology, many issues are problems of explanation, involving retrospective analyses to comprehend past impacts, such as those caused by the zebra mussel in the Great Lakes.
  • Methods Used: This sector uses various methods, including population dynamics studies, experiments, statistical analyses, and modeling, which require an in-depth understanding of:
    • Taxon natural history
    • Environmental factors
    • Social aspects surrounding invasive species
Prediction
  • Definition: Prediction refers to generating statements about the likelihood of future events occurring, distinct from mere explanation.
  • Criteria for Predictive Systems: A comprehensive review by the US National Research Council emphasized three essential criteria:
    1. Transparency and Peer Review: Predictive systems should be open to peer review and evaluation.
    2. Logical Framework: There should be a logical framework incorporating independent variables significant to the process.
    3. Repeatability: The system should yield the same outcomes regardless of the user.
  • Current Findings: As of the 2002 report, few predictive systems in invasion ecology fulfilled all three criteria.

Limitations of Prediction

Several factors can hinder the success of predictions:

  • Significant Effects with Little Variance Explained: Sometimes statistical significance (p < 0.05) does not correlate with strong explanatory power (low R² values).
  • Omission of Species: Some species may not be evaluated due to inadequate information or incompatibility with the test.
  • Danger of Extrapolation: Extrapolating from conditions that generate predictions can be hazardous, especially with non-linear or transformed data.
  • Introduction vs. Native Populations: The risk assessment is often based on introduced populations, which might exhibit different characteristics from their native counterparts, leading to inaccuracies.

Risk Assessment Overview

Risk assessment consists of various analytical techniques aimed at estimating the frequency and consequences of undesired outcomes.

Focus of Assessment

For invasive species, it typically involves analyzing:

  • Likelihood of Establishment: The chances of a species entering and establishing itself in a new region.
  • Potential Impact: Evaluating the likelihood and the type of impact the invasive species may have.
Types of Risk Assessments
  • Species-Focused: Evaluates specific species, usually with intentional introductions in mind.
  • Vector-Focused: Centred on pathways like pet trade or ballast waters concerning unintentional introductions.

Risk Assessment Protocols

Various governmental risk assessment protocols exist:

  • Australian Weed Risk Assessment: The most widely employed for permitting purposes.
  • US Ecological Risk Assessment Framework: Specifically for ecological impacts.
  • Generic Non-Indigenous Aquatic Organisms Risk Analysis: For aquatic organisms.
Common Structure of Protocols

Most protocols employ a structured approach using species traits and environmental characteristics to assess the likelihood of a species moving through all invasion stages. Typically, this structure includes:

  • A series of yes/no questions
  • A scoring system leading to a risk categorization (low, moderate, or high).
Australian Weed Risk Assessment Details
  • Contains 49 Questions covering:
    1. Biogeography: Distribution, climate, domestication, and previous establishment successes.
    2. Undesirable Attributes: Toxicity, unpalatability, and establishment in native communities.
    3. Biology and Ecology: Attributes enabling reproduction, spread, and persistence.
  • Acceptance Criteria: Responses yield scores leading to recommendations:
    • Accept
    • Evaluate further
    • Reject
  • Not all questions need to be answered if information is limited; however, a minimum within each category is required.
  • Statistics: The protocol has been successful, rejecting about 90% of known invasive species and accepting approximately 70% of non-invasive species.
Adaptation of Protocols

The Australian Weed Risk Assessment has been adapted for use in various locations such as Hawaii, the Czech Republic, Florida, and also for freshwater invertebrates.

Study on Question Relevance in Risk Assessment

Weber and colleagues (2009) analyzed the questions correlating with species categorizations in the Weed Risk Assessment over eight years:

  • Key Approximate Questions: Found that answering just three specific questions yielded comparable results to the full assessment.
    1. Whether the species is a congeneric weed
    2. Likelihood of unintended dispersal of propagules
    3. Ability to benefit from disturbances such as cultivation or fire.
  • The study indicates a more efficient assessment can potentially be achieved with fewer questions, allowing for high prediction accuracy with limited data.
Economic Aspects of Risk Assessment

Keller et al. (2007) found that conducting full Weed Risk Assessment offers net economic benefits. When accuracy is near 90%, positive returns could accrue within a decade, highlighting the cost-effectiveness of these assessments.

Addressing Unintentional Introductions

Simple questions that capture key attributes may not suffice for assessing unintentionally introduced species. Therefore, other methods like vector risk assessment are necessary.

Case Study: Ballast Water Analysis

Drake and Lodge (2004) presented an analysis of risks posed by ballast waters.

  • Method: Analyzed ship traffic data from 243 ports globally and employed complex network flow analysis.
  • Outcomes: They identified invasion hotspots and significant port-to-port linkages, with
    • Warm colors indicating increased invasion risk.
    • Notable hotspots included Europe and East Asia due to their active ports.
    • Temporal patterns indicated a rise in invasion risks in East Asia and other specific regions.
  • Vector Interruption Strategies: Findings suggested that reducing the introduction probability per ship was significantly more effective than targeting dominant ports.

Conclusion

To mitigate negative effects from invasive species, prevention of establishment is crucial. Nonetheless, due to human motivations for species introductions, maintaining control over species introductions might not always be feasible. Therefore, developing robust predictive power through risk assessments is essential. Future predictive efforts should:

  • Enhance datasets and analytical tools.
  • Include not just species-specific risks but also vector risk assessments.
  • Consider factors likely to alter invasion dynamics, including climate change, which could affect ecological conditions and human interactions with invasive species through transport and commerce.