4.1 macro invertebrates as ecological indicators-en

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  • 1. Some technical and backgroundinformation to supportdevelopment of river healthassessment programs
  • 2. Macroinvertebrates as ecological indcators• Macroinvertebrates most widely used biological indicator of stream health – Good performance in evaluating WQ, especially heavy metals, organic pollution – Efficient to sample – “Cosmopolitan” – similar groups in different parts of the world• However: – Less sensitive to changes in hydrology and physical form (geomorphology) – Do not quantify environmental “goods and services” such as fisheries production
  • 3. Two broad approaches• Multi-variate approaches – RIVPACS, AUSRIVAS• Multi-metric approaches – IBI, SIGNAL
  • 4. Multi-metric indicators (e.g. IBI, SIGNAL) 1. Combine a number of metrics describing the composition and tolerance of the invertebrate assemblages at a site. 2. Individual or combined metric scores compared against values derived from geographically similar reference sites – Multi-metric approach depends on fairly predictable patterns of tolerance of different invertebrate taxa (often Order/Family) to disturbance gradients
  • 5. Multivariate indicators (e.g.RIVPACS, AUSRIVAS) 1. Use statistical models based on reference sites to „predict‟ biota occurring at assessment sites. 2. Difference between observed (O) and expected (E) – (O/E) is used as „indicator. – Predictive models replace the use of regionalisation in deriving reference values – Initial development requires large datasets to build and validate statistical models – Less transferable than multi-metric methods
  • 6. AUSRIVAS (Australian River AssessmentSystem)• Developed as “Australia-wide” river health assessment program – Macroinvertebrates as indicator – Many years of development – Au$Millions – Still being refined – Not used in every state. – Not the only program of assessment.
  • 7. Statistical modelsSpeces occurrence ~ env. Predictor 1 + env. Predictor 2…
  • 8. Measuring impairment• OE metric considers taxa predicted to occur with a >50% probability based on site characteristics• OE ratio of these taxa used to assess impairment of site
  • 9. Multi-metric (IBI type approaches)• SIGNAL: Stream Invertebrate Grade number – Average Level• Each taxon is given a „sensitivity‟ score (0-10) – Reported as average score of all taxa recorded from a site
  • 10. Information to calculate SIGNAL score
  • 11. Method includes samplingrecommendations
  • 12. Manuals provide detailed steps
  • 13. Detailed data sheets provided for all fieldassessments
  • 14. Technical details vs implementation• Both „multivariate‟ (e.g. AUSRIVAS) and „multi- metric‟ scoring systems (e.g. SIGNAL, B-IBI) used in Australia – Both approaches shown to be effective at identifying polluted sites. – Approaches still being refined, especially for desert bio-regions Technical details of each method are important, but both approaches effective if properly applied
  • 15. Chessman (2003) NSW Dept infrastructure planning and Natural resources“We suggest that Australia relies too heavily on bioassessment concepts developedto assess water pollution in well-watered regions of the Northern Hemisphere.Effective assessment of human impacts on macroinvertebrates in the rivers of inlandAustralia requires a better understanding of the roles of flow regimes, including floodand drought se- quences, and of microhabitat structure and invasive alien species.”
  • 16. Reducing variance (s) in the results – Training programs – Accreditation of staff – Web-training, data reporting etc. – QA/QC at every stage of assessment
  • 17. QA/QC – staff training• Appropriate training and testing of staff involved in field and laboratory work• EPA (Australia) ID 20% of invertebrate samples twice for consistency.• Development of standard operating procedures• May involve collaboration between organisations - universities, research groups, central & provincial govt.
  • 18. AUSRIVAS: online training and accreditation
  • 19. Summarising experiences from Australia• River health monitoring and environmental flows assessment strategies take considerable time to develop, and evolve over time• 15+ years in Australia (>20 years in USA) – Changes in indicators – Refinement of targets and scoring systems• Technical details matter• Training and QA/QC equally as important to success of programs.