Steps 1 & 2: Defining the case & listing candidate causes for the Truckee River case study

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Step 1: Define the Case

List Candidate Causes

Evaluate Data from the Case

Evaluate Data from Elsewhere

Identify Probable Cause

Detect or Suspect Biological Impairment

As Necessary: Acquire Data

and Iterate Process

Identify and Apportion Sources

Management Action: Eliminate or Control Sources, Monitor Results

Biological Condition Restored or Protected

Decision-maker and

Stakeholder Involvement

Stressor Identification

• What biological effects are observed?

• Where & when are they occurring?

• Where are comparable reference sites?

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Defining the biological impairment

• Identify subset of biological measures to focus & guide SI process

• Choose wisely, & where possible, aim for specificity

SPECIFICITY EXAMPLES SI UTILITY

coarse failure to meet biological criteria triggering SI process

composite↓ sensitive taxa

↓ EPT taxalisting candidate causes

developing conceptual model

specific↓ Paraleptophlebia

absence of brook trout

grouping sitesdiagnosing

evaluating strength of evidence

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Let’s start defining your case…

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Defining the case: what, where & when

1. What biological effects do you want to focus on?

BUGS? FISH?

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Defining the case: what, where & when

2. Where are your impaired & reference sites?

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Defining the case: what, where & when

Which biological variables?invertebratesfish

Where does the biological variable change among your sites?

Which are your impaired and reference sites?

Which time scale?

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Defining the case: what, where & when

To Do:1. Load relevant data files

SiteinfoMetrics

2. Merge files

3. Make boxplots for each biological response variable

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Define the Case

Evaluate Data from the Case

Evaluate Data from Elsewhere

Identify Probable Cause

Detect or Suspect Biological Impairment

As Necessary: Acquire Data

and Iterate Process

Identify and Apportion Sources

Management Action: Eliminate or Control Sources, Monitor Results

Biological Condition Restored or Protected

Decision-maker and

Stakeholder Involvement

Stressor Identification

Step 2: List Candidate Causes

• Make a map• Gather information on

potential sources, stressors, and exposures

• Develop a conceptual model

• Engage stakeholders• Develop “final” list

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Let’s start by assembling a map…

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Listing candidate causes

• Hypothesized causes of impairment– Sufficiently credible to be analyzed– Focus on proximate stressor, or stressor directly inducing effect

of concern– May include sources, mechanisms of action, or several causes

acting together (causal scenarios)

• Develop list using:– Data from site– Info on known or potential sources– Existing knowledge from site, region & elsewhere– Stakeholder input

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Let’s start listing your candidate causes…

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Listing candidate causes: initial brainstorming

1. What sources are in watershed?

2. What stressors could be causing effects?

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• Strategies– Combine if they share causal pathways, modes of action,

sources & routes of exposure, or if they interact– Re-aggregate stressors that have been unnecessarily

disaggregated– Identify independently acting stressors that cause the same

effect– Define effects more specifically

Combining stressors

• Warnings– Avoid combining causes without an underlying model– Avoid broad candidate cause definitions– Don’t lose independent effects of individual causes

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Based on our brainstorming, let’s start developing a conceptual model…

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Developing a conceptual model

• What is it? – Diagram showing cause-effect

linkages among sources, stressors, & biological effects

• Used for:– Initial brainstorming– Analysis framework– Communication tool

SOURCE

STRESSOR

BIOTIC RESPONSE

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Using the conceptual models in CADDIS

• The stressor-specific diagrams are there to give you ideas, & get you thinking about what may be happening in your stream

• Take the parts that make sense for your system & leave the rest

• Pilfer & modify freely, to generate case-specific diagrams

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Things to keep in mind in model development• Think about causal pathways

—How do sources lead to stressors?—How do stressors lead to biological effects?

• Be as specific as possible—You do not need data for every component in your

diagram—Want to identify potential data sources & types of evidence—General vs. specific impairments

• Be thorough & inclusive—You can always eliminate potential sources, pathways, etc.

later on, but don’t limit your initial brainstorming

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Keeping all that in mind, let’s start drawing!

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The “final” list of candidate causes

• Fill in with final list…

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Now that we have a diagram, where do the data fit in?