C leigh river health indicators and assessment nov2010


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C leigh river health indicators and assessment nov2010

  1. 1. River health indicators andassessmentDr Catherine LeighAustralian Rivers Institute, Griffith University, Australia
  2. 2. 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 adaptationRiver Health Indicators and Assessment
  3. 3. 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 reportingRiver Health Indicators and Assessment
  4. 4. Flow chart of the process Conceptual models Land-use Assess indicator assessment to Identify suite of Field trial sensitivity to define potential indicators disturbance disturbance gradient gradient Consider for yes No Did the indicator Review inclusion in respond as expected? indicator scorecard Do standards already exist No Can thresholds and (Chinese or international) targets be established from the data? No yes yes Consider for River Adopt appropriate Include in futureClassification standard scorecard programs Steps in developing a river health program
  5. 5. 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 indicatorsRiver Health Indicators
  6. 6. 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 changeRiver Health Indicators
  7. 7. Types of ecosystem response indicatorswe 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 websRiver Health Indicators
  8. 8. 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 River Health Indicators
  9. 9. Biological indicators show structural andfunctional 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)River Health Indicators
  10. 10. Invertebrates as response indicatorsWhy 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 timeRiver Health Indicators
  11. 11. 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 thoroughlyRiver Health Indicators
  12. 12. 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 valueRiver Health Indicators
  13. 13. 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 fishRiver Health Indicators
  14. 14. Some other things to consider aboutindicators…• 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?River Health Indicators
  15. 15. Flow chart of the process Conceptual models Land-use Assess indicator assessment to Identify suite of Field trial sensitivity to define potential indicators disturbance disturbance gradient gradient Consider for yes No Did the indicator Review inclusion in respond as expected? indicator scorecard Do standards already exist No Can thresholds and (Chinese or international) targets be established from the data? No yes yes Consider for River Adopt appropriate Include in futureClassification standard scorecard programs Scoring and assessing river health
  16. 16. 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)Scoring and assessing river health
  17. 17. An example: Macroinvertebrate EPT richness• 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 notScoring and assessing river health
  18. 18. Reference or benchmark for indicatorsWhat is „healthy‟ and what is not? X Scoring and assessing river health
  19. 19. Benchmarking selected indicators, scoringand 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 systemsScoring and assessing river health
  20. 20. Benchmarking selected indicators, scoringand 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 adaptationScoring and assessing river health
  21. 21. 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 Scoring and assessing river health
  22. 22. 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”)Scoring and assessing river health
  23. 23. Disturbance Gradient• The disturbance gradient approach is used South-East Queensland in Australia• Indicators are tested against an appropriate disturbance gradient (e.g. land use) – Those indicators best able to detect changesEcological health indicator in ecological condition are then included in monitoring programs – Indicator values under low human disturbance may be predicted from the Reference values modelled relationships Low High Disturbance gradient Scoring and assessing river health
  24. 24. So there are many different options forbenchmarking…• 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 knowledgeThe option chosen must be the most appropriate for the particular river health program and the river system in questionScoring and assessing river health
  25. 25. 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‟Scoring and assessing river health
  26. 26. An example: Macroinvertebrate EPT richness• 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)Scoring and assessing river health
  27. 27. 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))Scoring and assessing river health
  28. 28. An example: Macroinvertebrate EPT richness • 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 timeScoring and assessing river health
  29. 29. Scoring and assessing river health• 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 etcScoring and assessing river health
  30. 30. Aggregating scores: a Queensland example Seasonal site index measurement 127 sites monitored twice per (raw data) year (Spring and Autumn) 14 Indices x 127 sites x 2 seasons Index measurement compared to target and worst-case scenario values = Standardised Score (0-1) Seasonal site index score (0-1) 14 Indices x 127 sites x 2 seasons Fish Standardised scores Invertebrates for indices in each of 5 Indicator Groups Nutrients averaged Physico-chemical (0-1)Seasonal site indicator group score (0-1) Ecosystem processes 5 Indicator Groups x 127 sites x 2 seasons Scoring and assessing river health
  31. 31. 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 teamScoring and assessing river health
  32. 32. Thank you! Many thanks to CRAES, Zhang Yuan, Qu Xiaodong, Kong Weijing, and Nick Bond