4.1 macro invertebrates as ecological indicators-en
Some technical and backgroundinformation to supportdevelopment of river healthassessment programs
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
Two broad approaches• Multi-variate approaches – RIVPACS, AUSRIVAS• Multi-metric approaches – IBI, SIGNAL
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
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
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.
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
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
Detailed data sheets provided for all fieldassessments
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
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.”
Reducing variance (s) in the results – Training programs – Accreditation of staff – Web-training, data reporting etc. – QA/QC at every stage of assessment
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.
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.