C leigh river health indicators and assessment nov2010

River health indicators and assessment

Dr Catherine Leigh

Australian Rivers Institute, Griffith University, Australia

This afternoon‟s presentation outline

• First session (Cath Leigh):

– Indicators and benchmarking for

scoring and assessing river health

• Second session (Nick Bond):

– Things to think about

• Quality assurance

• Site selection

• Pressure indicators

• Classification

• Refinement and adaptation

River Health Indicators and Assessment

First Session: Outline

• The process of developing a river health monitoring and

assessment program

• Some commonly used indicators

• Benefits and limitations of different indicators

• What does an indicator value actually mean in terms of river

health?

– How do you standardise and compare indicators among sites and

through time (how do you score river health)?

– Does the score make sense?

• Different ways to combine scores for reporting

River Health Indicators and Assessment

Flow chart of the process

Field trial Assess indicator

sensitivity to

disturbance

gradient

Identify suite of

potential indicators

Land-use

assessment to

define

disturbance

gradient

Adopt appropriate

standard

Did the indicator respond as expected?

Consider for

inclusion in

scorecard

Can thresholds and

targets be established

from the data?

Do standards already exist (Chinese or international)

Review

indicator

Include in

scorecard

River

Classification

yes

No

Consider for

future

programs

No

yes

yes No

Conceptual

models

Steps in developing a river health program

What are “indicators of river health”?

• River „health‟ can be assessed using indicators

of a river‟s ecological condition in terms of its

physical, chemical and biological attributes

• These indicators must be efficient, rapid and

founded on ecology, and must also

– be responsive to environmental changes

– be comparative over different ecological

regions, and

– report on the whole ecosystem condition

• No shortage of potential indicators

River Health Indicators

Different kinds of indicators…

• Pressure Indicators (indicators of

human disturbance)

– Measures of hydrological alteration

– Indicators of channel modification

– Land-use change indicators

– Measures of nutrient and sediment inputs

– Indicators of exotic and/or invasive species‟

introductions

• Ecosystem Response Indicators

– Indicators of an ecosystem response to

environmental change


Types of ecosystem response indicators

we typically use.....

• Water quality indicators

– Dissolved oxygen, conductivity, pH, turbidity, nutrients, anions and cations, heavy metals

• Biological pattern indicators

– Fish Assemblage Composition

• Various indicators using richness, abundance, presence/absence of species

– Macroinvertebrate Assemblage Composition

• Various indicators (e.g. richness) and predictive models (e.g. AusRivAs observed versus expected)

• Process and biological function indicators

– Primary production, benthic metabolism and nutrient cycling, decomposition, fish body condition, food webs


Why monitor beyond water quality?

• There are other forms of human disturbance to rivers that we want to detect besides pollution

• Water quality is highly variable through time, biological indicators tend to be less so

• There are more pollutants than it is possible to measure

• Pollutants interact and cause synergistic effects that may be unknown

• Biological indicators integrate through time

and across multiple stressors


Biological indicators show structural and

functional responses

• Biotic communities and populations show structural changes in

response to disturbance

• Change in diversity (usually decreases)

• Change in abundance (sometimes increases)

• Loss of certain groups (loss of diversity and/or abundance)

– E.g. sensitive macroinvertebrate taxa like Trichoptera (caddisflies),

Ephemeroptera (mayflies) and Plecoptera (stoneflies) = EPT taxa

• They also have functional and process responses to disturbance

• Change in condition (e.g. fish body weight to length ratio usually

decreases)

• Change in food webs (e.g. fish predator to prey ratios usually decreases)

• Change in recruitment / reproduction (e.g. number of young fish in the total

fish population usually decreases)


Invertebrates as response indicators

Why use invertebrates?

– Ubiquitous (found almost everywhere)

• occur in most habitats across a diverse range of aquatic systems

– Many species and families

• have a broad range of responses to disturbance

– Sedentary

• effective spatial analyses of pollutants or disturbance effects

– Relative longevity

• They can be used to assess changes through time


Invertebrates as response indicators

• Some limitations – typically used for small or wadeable streams (edge and riffle

habitats) rather than large, un-wadeable rivers

– taxonomy may be poorly developed for some regions (hard to identify all species)

– taxonomic identification and sample processing can be intensive and take a long time depending on the level of identification required

– multiple samples or compositing of samples from one site may be required to reduce variation between samples / sample the river community thoroughly


Fish as response indicators

• Why use fish? – Life history information often available

– Feed at many different levels of the food web

– Biological integrity can be assessed rapidly (using metrics)

– Both acute toxicity & stress effects can be assessed

– Affected by large-scale factors

– Commonly used to assess large, non-wadeable rivers

– Often long-lived – integrate temporal changes

– Have social and cultural value


Fish as response indicators

• Some limitations

– Some species may be sparsely distributed, others may school

(this creates patchy distributions)

– They may travel between impacted and non-impacted areas

– Little may be known about juvenile stages making it harder to

assess recruitment

– More difficult to sample in a systematic way

– Fish catch can be affected by effort

– Different sampling methods may catch different types of fish


Some other things to consider about

indicators…

• The program‟s objectives; the conceptual understanding of the

river system; the key human disturbances; the identified important

ecological, social and economic assets

• How responsive the indicators are to the disturbances?

• How likely the indicators are to reflect a response to river health

management (reduction in disturbance)?

• Indicator redundancy

– How unique is each indicator (what important information does it tell us about

the river‟s ecological integrity)?

• What level of training is required to collect, maintain and analyse

data for the indicators?


Flow chart of the process

Field trial Assess indicator

sensitivity to

disturbance

gradient

Identify suite of

potential indicators

Land-use

assessment to

define

disturbance

gradient

Adopt appropriate

standard

Did the indicator respond as expected?

Consider for

inclusion in

scorecard

Can thresholds and

targets be established

from the data?

Do standards already exist (Chinese or international)

Review

indicator

Include in

scorecard

River

Classification

yes

No

Consider for

future

programs

No

yes

yes No

Conceptual

models

Scoring and assessing river health

An example: Macroinvertebrate EPT richness

• In the Taizi River Pilot Study, one indicator we tested was EPT richness

– Family level identification of macroinvertebrate taxa from each site

– Number of different families within Ephemeroptera (E), Plecoptera (P) and Trichoptera (T) was calculated

– EPT family richness (EPT_S)

• EPT_S had significant statistical relationships with the disturbance gradient (showed the expected response)



• Values for EPT_S in the Taizi study area were higher in the Mountainous region than in the Lowland region

• But what do these values mean in terms of river health and how do we compare between sites?

• How do we standardize the values so we can score EPT_S and compare among sites?

• We need to know what values represent a „healthy‟ river and what values do not


What is „healthy‟ and what is not?

Reference or benchmark for indicators

X Scoring and assessing river health

Benchmarking selected indicators, scoring

and assessing river health

• To report on (score and assess) river health, values can be set for

each of the selected indicators that reflect different levels of health

(this is called „benchmarking‟)

• It is important, therefore, to agree on levels that distinguish

between „good‟ (target or reference) and „bad‟ (unacceptable)

condition in a particular river based on:

– River type (Classification)

– River health program‟s objectives

– Management objectives for that river

• Different reporting programs often use different benchmarking

and/or scoring systems


Benchmarking selected indicators, scoring

and assessing river health

• A reference point or benchmark for indicators sets a value that we

expect at a site in a state of „good‟ health

– Logical reference point is the expected condition of a site if undisturbed by

human activity

– In practice though, such sites will not exist in all river regions

• How can we make sensible conclusions about results of the monitoring?

– Reference Condition Approach

– Synthetic Reference Condition Approach

– Disturbance Gradient Approach

– Expert opinion and local knowledge

– Refinement and adaptation


Reference Condition

• The “reference condition” approach relies on comparing test

sites with others in “reference condition”

• These may be in a natural “un-impacted” condition or have

habitats in “best attainable” natural condition


Synthetic Reference Condition

• Synthetic “condition” is generated through conceptual models,

expert opinion and long-term datasets

• The Synthetic Reference Condition can theoretically be set at

any „point‟ that is seen to be desirable (in terms of “good

ecological condition”)


Disturbance Gradient

– Those indicators best able to detect changes

in ecological condition are then included in

monitoring programs

– Indicator values under low human

disturbance may be predicted from the

modelled relationships

Disturbance gradient

Low High

Ecolo

gic

al health indic

ato

r

Reference values

• The disturbance gradient approach is used South-East Queensland

in Australia

• Indicators are tested against an appropriate disturbance gradient (e.g.

land use)


So there are many different options for

benchmarking…

• Indicator values from reference sites (if available)

• Historical or modelled data (before to a particular disturbance)

• Data from similar systems elsewhere in good condition (this is an

example where the classification step in developing a river health

program is important)

• Comparison with values derived from indicator-disturbance

relationship models

• Established criteria or standards (often applied to water quality)

• Expert opinion and local knowledge

The option chosen must be the most appropriate for the particular

river health program and the river system in question


Setting a decision framework

• It may be important to establish a decision framework by which to determine potential target values („good‟ health) and values that represent „bad‟ or „unacceptable‟ health for each of the chosen indicators. (These are the values that can be used to „score‟ the health of each site)

• The framework provides the rationale as to how and why the values were chosen for each indicator – e.g. why an established guideline was used for one indicator, but a reference condition value was used for another

• Expert opinion, local knowledge, and an understanding of the program‟s objectives must also be kept in mind when applying such a decision framework and when checking to see if the results „make sense‟



• Looking again at our example of EPT_S values…

• No true reference sites in the study region; but there are some well researched

guideline values from different parts of the world with similar types of rivers

• We can compare these with the EPT_S values in the Taizi and use expert

knowledge to guide our choice of suitable target and threshold values

• We also consider the river classification (so we compare like with like); do we

expect different EPT richness in different regions of the Taizi?

• We also consider the program‟s objectives – to improve biotic diversity and

decrease impacts of human disturbance on biota

• So… we used a combination of expert opinion, published values in the literature and unpublished data from undisturbed streams and ‘reference condition’ rivers in China and other parts of the world with similar environmental characteristics (climate, topography etc)

• We then compared these values with our own data to establish sensible EPT_S values that represented ‘target’ (excellent health) and ‘worst-case scenario’ (the ‘fail’ value, extremely bad health) for each reporting region (Uplands, Midlands, Lowlands)


Next step: Score and assess river health

• Different methods can be used to score river health

• E.g. the Australian EHMP and USA EPA health programs use a

standardised scoring system that gives each site a score between

0 and 1 for each indicator:

• If indicators increase in value with disturbance:

Score = 1 – ((Observed site value – Target value)/ (Fail value – Target value))

• If indicators decrease in value with disturbance:

Score = 1 – ((Target value – Observed site value)/ (Target value – Fail value))



• EPT_S decreases in value with disturbance

• e.g. for each site:

Score = 1 – (Target value – Observed EPT_S value)

(Target value – Worst-case Scenario value)

• This produces scores for each site that have meaning in terms of the

sites‟ level of ecological condition

• These scores can be compared with each other (in space) and through

time



• Scores for indicators within indicator groups can be aggregated in

many different ways

• This might be done by taking the average score for the indicators,

or the minimum score etc.

– The minimum score might be appropriate if a poor score from any of

the individual indicators was particularly detrimental to overall

ecosystem health

• Scores can also be aggregated across sites to provide an overall

score for each of the river regions.

– For example, this could be done by averaging each of the indicator

group scores across sites within each river region, or by taking the

minimum score etc


Aggregating scores: a Queensland example


Seasonal site index measurement (raw data)

14 Indices x 127 sites x 2 seasons

Seasonal site index score (0-1) 14 Indices x 127 sites x 2 seasons

Seasonal site indicator group score (0-1) 5 Indicator Groups x 127 sites x 2

seasons

Index measurement compared to target and worst-case scenario values =

Standardised Score (0-1)

Standardised scores for indices in each of 5 Indicator Groups

averaged (0-1)

127 sites monitored twice per

year (Spring and Autumn)

Fish

Invertebrates

Nutrients

Physico-chemical

Ecosystem processes

Different levels of health between 0 and 1

• If desired, different levels of health (e.g. of low or high concern)

could be set for each indicator score (somewhere between 0 and1)

• Also, what score between 0 and 1 is the cut-off between passing or

failing river health?

• This cut-off value may depend on the ecosystem health objectives

and/or management actions applicable to the site, river section or

reporting region

• For example, a score of 0.2 or more may be considered

acceptable for a site in a designated industrial zone where little or

no ecosystem health management is expected, but a score less

than 0.7 might be considered a fail for a site in a nature reserve

• These scoring options and their implications for ecosystem health,

management and reporting must be considered carefully and in

light of the program‟s overall objectives and by the whole team


Thank you!

Many thanks to CRAES, Zhang Yuan, Qu Xiaodong,

Kong Weijing, and Nick Bond

Technology

C leigh river health indicators and assessment nov2010