Steps 1 & 2: Defining the case & listing candidate causes

Steps 1 & 2: Defining the case & listing candidate causes

2

• Fish kills

• Organismal anomalies

• Changes in community structure

• Low biotic index values

• Violation of biocriteria

Define the Case

List Candidate Causes

Evaluate Data from the Case

Evaluate Data from Elsewhere

Identify Probable Cause

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

Detect or suspect biological impairment

3

What triggered SI at Pretend Creek?

PC1

PC2

Pretend Springs city limit

NC1

NC2

Pretend Creek

Nearby Creek

macroinvertebrate IBI = 22

macroinvertebrate IBI = 64

4

• What biological effects are observed?

• Where & when are they occurring?

• Where are comparable reference sites?

Step 1: Define the Case

List Candidate Causes




Detect or Suspect Biological Impairment


and Iterate Process




Decision-maker and



5

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

6

Example: fish kills in Virginia & West Virginia

WHERE?

7

Example: fish kills in Virginia & West Virginia

WHAT?

WHEN?March–May 2006

Acute phase (mid-March) Chronic phase (March–May)

smallmouth bass

redbreast sunfish

VA

redhorse sucker

WV

smallmouth bass

northern hogsucker

May 25–31, 2006

Acute phase only

8

PC1

PC2


NC1

NC2

Pretend Creek

Nearby Creek

0

50

100

PC1 PC2 NC1 NC2

Site

EP

T t

axa

ric

hn

ess

(% o

f P

C1)

Defining the case for Pretend Creek

9

Defining the case for Pretend Creek

PC1

PC2


NC1

NC2

18 EPT generabrook trout

8 EPT generano brook trout

Pretend Creek

Nearby Creek

10

• Make a map

• Gather information on potential sources, stressors, and exposures

• Develop a conceptual model

• Engage stakeholders

• Develop “final” list

Define the Case




Detect or Suspect Biological Impairment


and Iterate Process




Decision-maker and



Step 2: List Candidate Causes

11

forest

forest

PC1

PC2


NC1

NC2

forest dairy farm

subdivision

unimpaired siteimpaired siteWWTPindustrial facilitydam

Include pollution sources & other environmental conditions or factors that affect which candidate causes are listed

12

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

13

• 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

14

Example: Willimantic River, CT

POTW

MR3

MR1

1. Toxicity from metals, ammonia, or complex mixture

2. Removal of organisms during high flows

3. Loss of interstitial habitat due to settled particles

4. Asphyxiation due to low dissolved oxygen

5. Mortality due to thermal stress

6. Taxa loss due to altered food resources

15

Example: fish kills in Virginia & West Virginia1. Low dissolved oxygen in water2. Gill damage from ammonia, high pH, or other mechanism

prevents uptake of oxygen3. Altered blood chemistry from nitrite exposure prevents fish

from using oxygen

4. Viral, bacterial, parasitic, or fungal infections

5. Mortality from high pH6. Mortality from pH fluctuations7. Mortality from ammonia toxicity

8. Toxicity of unspecified substances

9. Starvation due to inadequate food resources

16

17

Listing advice for candidate causes

• 8 common candidate causes

• Basic information:–Definition of candidate cause–Sources–Site evidence–Biological effects–When to exclude–How to measure–Relevant literature reviews–Generic conceptual model

• Metals

• Sediments

• Nutrients

• Dissolved oxygen

• Temperature

• Ionic strength

• Flow alteration

• Unspecified toxic chemicals

18

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

19

20

“Generic” conceptual model for sediment

Simple conceptual model diagram for SEDIMENTDeveloped 7/2007 by Kate Schofield & Susan Cormier

insufficient sediments

↓ plants or biofilm

↑ suspended sediments ↑ deposited & bedded sediments

↓ light

↓ visibility↓ visibility

Δ filter-feeding efficiency

Δ filter-feeding efficiency ↑ abrasion↑ abrasion

↑ sediment oxygen demand


↓ interstitial spaces

↓ interstitial habitat & flow↓ interstitial

habitat & flow

↓ substrate size

↓ substrate diversity & stability


↑ coverage by fines

↑ fine substrate habitats


↑ burial↑ burial

↑ pool in-filling↑ pool

in-filling

↓ water velocity & discharge

↑ deposition↑ deposition

other biological impairments

biologically impaired invertebrate assemblages

biologically impaired fish assemblages other biological impairmentsother biological impairments

biologically impaired invertebrate assemblagesbiologically impaired invertebrate assemblages

biologically impaired fish assemblagesbiologically impaired fish assemblages

↓ habitat↓ habitat

Δ sediment in streamΔ sediment in stream

↑ sediment in discharged waters


↑ mobilization of bank & channel sediment


↑ water velocity & discharge

↓ availability of bank & channel sediment↓ availability of bank & channel sediment

↓ sediment in discharged waters


↓ deposition on floodplain


watershed soils

watershed soils

channel sedimentchannel

sedimentstreambank

sedimentstreambank

sediment

upstream impoundment


point source discharges


↑ watershed erosion


↑ sediment delivery to stream


watershed land cover alterationwatershed land cover alteration

riparian land cover alteration


channel alterationchannel alteration

↓ sediment delivery to stream


↓ deposition↓ deposition

↑ streambank erosion↑ streambank erosion

biotic response

proximate stressor

source

additional step in causal pathway

LEGEND

interacting stressor

mode of action

contributing landscape change

biotic responsebiotic response

proximate stressor

sourcesource



LEGEND


mode of actionmode of action



↑ heat absorption

↑ heat absorption

21





↓ light








habitat & flow

↓ substrate size








in-filling




















watershed soils

watershed soils


sedimentstreambank

sedimentstreambank

sediment

















biotic response

proximate stressor

source


LEGEND


mode of action



proximate stressor

sourcesource



LEGEND





↑ heat absorption

↑ heat absorption

Conceptual model components in CADDIS

origination points, areas, or entities that release or emit agents

biological results of exposure to proximate stressor

stressors that directly induce biological effect of concern

other stressors that influence or are influenced by the focal stressor

changes that affect delivery of agents to stream

22

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

23

Case-specific conceptual models: Long Creek, ME

↓ dissolved oxygen

↑ temperature

↓ large woody debris

↓ brook trout

↓ EPT taxa↑ non-insect taxa

↑ HBI score

detention basins

Δ flow regime

Δ water velocity

↓ water depth

↓ wetted channel

↑ rate or magnitude of flow fluctuations

↑ toxic substances

↑ NaCl↑ ionic content

↑ metals↑ organics ↑ pesticides

↑ NH3

↑ sediment

↑ suspended sediment

↑ deposited sediment

↑ autochthony

↑ autochthonous food resources

↓ allochthonous food resources

instream impoundment

watershed devegetation

channel alteration

riparian devegetation

impervious surfaces

industrial processes

lawn care & landscaping

landfill leachate

sanding, salting & plowing instream

deposits

1

2

3 4

56

7

24


↑ temperature

↓ large woody debris

↓ brook trout

↓ EPT taxa↑ non-insect taxa

↑ HBI score

detention basins

Δ flow regime

Δ water velocity

↓ water depth

↓ wetted channel

↑ rate or magnitude of flow fluctuations

↑ toxic substances

↑ NaCl↑ ionic content

↑ metals↑ organics ↑ pesticides

↑ NH3

↑ sediment

↑ suspended sediment

↑ deposited sediment

↑ autochthony

↑ autochthonous food resources

↓ allochthonous food resources

instream impoundment

watershed devegetation

channel alteration

riparian devegetation

impervious surfaces

industrial processes

lawn care & landscaping

landfill leachate

sanding, salting & plowing instream

deposits

Case-specific conceptual models: Long Creek, ME

25

Case-specific conceptual models: Little Scioto River, OH

source

proximate stressor response

KEY


↑ fish weight

↑ DELT anomalies

↑ % tolerant invertebrates

↓ % mayflies

channel modification

↑ pool depth ↓ woody debris

↑ un-ionized ammonia (NH3)

↑ algae

↑ pH


↑ BOD

↑ TOC

landfill leachate

↑ metals ↑ PAHs

↑ total ammonia (NH4

+ + NH3)

↓ riffles

↑ sediment

↑ channel incision

2

4

5 6 71 3

↑ nutrients (N and/or P)

municipal waste

fertilizer use

industrial effluent

combined sewer overflow

hazardous waste site leachate

↑ UV light

26

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

forest

forest

PC1

PC2


NC1

NC2

forest dairy farm

subdivision

unimpaired siteimpaired siteWWTPindustrial facilitydam

Let’s go back to Pretend Creek…

28

Developing a conceptual model for Pretend Creek

CANDIDATE CAUSES?

KNOWN IMPAIRMENTS ↓ EPT richness ↓ trout abundance

industrial facilities subdivisionKNOWN SOURCES urbanization damdairy

farm

Candidate cause – hypothesized cause of impairment

Proximate stressor – stressor that directly induces biological effect of interest

29

EXAMPLE CANDIDATE CAUSES

↓ dissolved oxygen ↑ metals↑ temperature

Developing a conceptual model for Pretend Creek

industrial facilities subdivisionKNOWN SOURCES urbanization damdairy

farm

KNOWN IMPAIRMENTS ↓ EPT richness ↓ trout abundance

30

Let’s give it a try…

• Break into groups – 1 group per poster

• Arm yourselves with sharpies

• Mark up posters to generate conceptual models for Pretend Creek

31





↓ light








habitat & flow

↓ substrate size








in-filling




















watershed soils

watershed soils


sedimentstreambank

sedimentstreambank

sediment

















biotic response

proximate stressor

source


LEGEND


mode of action



proximate stressor

sourcesource



LEGEND





↑ heat absorption

↑ heat absorption

Conceptual model components in CADDIS

origination points, areas, or entities that release or emit agents

biological results of exposure to proximate stressor

stressors that directly induce biological effect of concern

other stressors that influence or are influenced by the focal stressor

changes that affect delivery of agents to stream

32

An example conceptual model for Pretend Creek…

33

dairy farm


↑ metals

↑ temperature

↓ EPT richness↓ brook trout

abundance

urbanization subdivision

industrial facilities

↑ impervious surfaces

↑ nutrients

↑ primary producers

pesticides

↓ riparian cover

↓ DO-sensitive taxa

↓ coldwater taxa

animal wastes

industrial effluent

↑ heated surface runoff

↑ DELTs

↑ parasitism & disease ↑ gasping

behavior

industrial leachate

↑ toxics in surface runoff

septic systems

deicers

↑ respiration & decomposition

↓ metal-sensitive taxa

dam

↑ water retention

Documents

Steps 1 & 2: Defining the case & listing candidate causes