Establishing Cause Effect Relationships in Multi Stressor Environments

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Establishing Cause- Effect Relationships in
Multi- Stressor Environments

• John Newberry

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Pollution in Riverine Environments

• Multiple sources
• Effluent exposure
• Interaction of stressors

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Impacts

• Incremental
• Multiple source
• Multiple stressor

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Approaches

• Laboratory toxicity tests
• Field bioassessments/ experiments
• Simulation modeling
• Hybrid methodologies

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Causal Criteria

• Strength of association
• Consistency of association
• Specificity of association
• Time order or temporality
• Biological gradient
• Experimental evidence
• Biological plausibility

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Field and Bioassay Experiments

• Nutrient- diffusing substrates (NDS)
• Exposure bioassays
• Postexposure bioassays

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Artificial Stream Experiments

• Greater complexity
• Stream mesocosms