mj paul tetra tech inc. center for ecological sciences rtp, nc using biological responses in...

MJ PaulTetra Tech Inc.Center for Ecological SciencesRTP, NC

USING BIOLOGICAL RESPONSES IN

NUTRIENT CRITERIA DEVELOPMENT: APPLICATIONS,

OPPORTUNITIES, AND CONCERNS

We can simplify the linkages

This has Clean Water Act implications

NUTRIENT POLLUTION IMPACTS BIOLOGY

40 CFR § 131.11 Criteria

States must adopt water quality criteria that protect designated uses, based on science and composed of suffi cient parameters;

These should be: Numeric or; Narrative “where numerical criteria cannot be established or to

supplement numerical criteria”

Focus has been on deriving numeric nutrient criteria How is this done? 4 major approaches – often in a weight of evidence approach

NUTRIENT CRITERIA DEVELOPMENT

Reference based – biology can be used here

NUMERIC NUTRIENT CRITERIA DEVELOPMENT

TP

(ug

/L)

0.0001

0.001

0.01

0.1

1

10

25th

75th

90th

PIEDMONT TN MODELLogTN = 0.1 + 0.49*Agriculture + 0.14*Urban

TN = 100.1 = 1.0 mg/L

Nu

trie

nt

Co

nce

ntr

atio

n

Non-Forested Land CoverNon-Forested Land Cover

Stressor-response based – biology most definitely used here


S CI2 0 0 7 = 3 0 .7 2 7 6 -6 .5 0 5 8 *x; 0 .7 5 P re d .In t.

-6 -5 -4 -3 -2 -1 0 1 2

L n T P

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

SC

I20

07

Ln(TP)

IBI Sco

re

Mechanistic Models E.g., WASP, QUAL-2k, EFDC, CE-QUAL, HSPF, MIKE… Model specific endpoints to generate nutrient goals


Scientific Literature


Outcome – numeric value One or more lines of evidence

NUMERIC NUTRIENT CRITERIA

45 mg/L

70 mg/L

40 mg/L

55 mg/L

Distribution

Stressor-response

Literature

Models

65 mg/L

Typically criteria are implemented as they are written: E.g., 40 ug/L annual average not to be exceeded more than

1 in 3 yearsWith nutrients, some states have proposed linked

biological and nutrient criteria:

Or as a multimetric: Composite Criteria = Pchla + PDO + B + N

IMPLEMENTING NUMERIC NUTRIENT CRITERIA

Biology ok

Biology not ok

Nutrients ok Nutrients not ok

Not Impaired Not ImpairedFurther Study

ImpairedNeed Cause

Nutrient Impaired

Why? Lack of cause-effect Variability of response of algae/invertebrates/water

chemistry to nutrient enrichment Cannot reliably predict a value that will produce aquatic life

use impact False positives would be costly

LINKED BIOLOGICAL AND NUTRIENT CRITERIA

A B C

D

X X

X

S CI vs. L n (T P )A l l Ha b i ta t S co re s

-6 -5 -4 -3 -2 -1 0 1 2 3

L n T P

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

SC

I20

07

L n T P :S CI2 0 0 7 : y = 3 6 .4 7 8 9 - 4 .5 0 3 6 *x; r2 = 0 .0 9 1 5

Ln(TP)

IBI Sco

re

If nutrient concentrations cannot predict biological response, then how can a biological response be used to infer nutrients are too high? If they can, why do you need confirmation?

Does not improve with a “building the case” approach If cannot reliably link nutrients to algae, DO and/or IBI, then

how can they be combined to infer a numeric nutrient impairment?

LINKED BIOLOGICAL AND NUTRIENT CRITERIA ISSUES

A BX

A BX C DX X

If models are inaccurate, immediately concluding that biological impacts are due to nutrients is questionable stressor identification


What would such an approach open up for other criteria (e.g., priority pollutants)? E.g., Cd limits derived to protect 5 th percentile of sensitive

lab species Combine with proof of in-stream aquatic life impact?


Waiting for evidence of impacts on aquatic life use before acting on nutrient pollution may confl ict with 131.11(a) - States must adopt water quality criteria that protect designated uses;

It is also ecologically risky…


“Expectations that ecosystems will return to original conditions …following reduced nutrient inputs may be fundamentally flawed….”

Reduce the variability – a big part of our problem may be classification…

Accept and apply risk based reasoning Derive numbers based on reducing the risk of impacts, not

on being 100% correct; Existing water quality criteria are very precautionary

SOLUTIONS

S CI vs. L n (T P )A l l Ha b i ta t S co re s

-6 -5 -4 -3 -2 -1 0 1 2 3

L n T P

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

SC

I20

07

L n T P :S CI2 0 0 7 : y = 3 6 .4 7 8 9 - 4 .5 0 3 6 *x; r2 = 0 .0 9 1 5

S CI2 0 0 7 = 3 0 .7 2 7 6 -6 .5 0 5 8 *x; 0 .7 5 P re d .In t.

-6 -5 -4 -3 -2 -1 0 1 2

L n T P

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

SC

I20

07

Classification

Ecology

Incorporate the variability into the criteria setting step, not the assessment step If response conditions are fine and nutrients elevated

(within an acceptable range), then refine numeric nutrient criterion site-specifically

Such an approach protects existing biological conditionfrom nutrients rather than requiring proof of impactbefore action

SOLUTIONS

Incorporate measures with safety levels – range concept Reference based values = lower trigger Stressor-response based values (invertebrate/fish) = upper

values

But, use biological measures EARLY in the causal pathway

SOLUTIONS

Listed for

Nutrients

Not Listed

Listed for

Nutrients

Not ListedSSC

Listed for

NutrientsListed

for Nutrient

s

Nutrient Threshold Exceeded

Bio

logic

al Thre

shold

Exc

eeded

No Yes YesLow High

Yes

No

Incorporate early warning measures for bio-confirmation

SOLUTIONS

SOLUTIONS

Require proof on multiple biological endpoints If nutrients elevated, but chlorophyll is not; then you need

to confirm that all aspects of aquatic life are okay. Nutrients can affect many aspects of aquatic life in streams

(even shaded headwaters):

Algae

Invertebrates Fish

Bacteria Fungi

Function

SOLUTIONS

This discussion is all VERY good for biology Whichever way it goes Bio-confirmation or No (Focus on ALU)

Support technical research Fund more experimental work

Field and lab dosing experiments Develop and apply statistical approaches for

reducing variability Develop new and refine existing biological

response tools

Ask experts what they think

SOLUTIONS

THANKS

Huffy The Bug Slayer

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