Some technical and background information to support development of river health assessment 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 Assessment

System)• 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.

Statistical models

Speces occurrence ~ env. Predictor 1 + env. Predictor 2…

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

Information to calculate SIGNAL score

Method includes sampling

recommendations

Manuals provide detailed steps

Detailed data sheets provided for all field

assessments

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

“We suggest that Australia relies too heavily on bioassessment concepts developed

to assess water pollution in well-watered regions of the Northern Hemisphere.

Effective assessment of human impacts on macroinvertebrates in the rivers of inland

Australia requires a better understanding of the roles of flow regimes, including flood

and drought se- quences, and of microhabitat structure and invasive alien species.”

Chessman (2003) NSW Dept infrastructure

planning and Natural resources

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.

AUSRIVAS: online training and accreditation

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.