Principal Investigators: M. Thoms and R. Norris
Research Officers: M. Parsons and G. Ransom
Cooperative Research Centre for Freshwater Ecology
Monitoring River Health Initiative Technical Report Number 23
Environment Australia, 2002
ISSN 1447 1280
ISBN 0 642 54889 7
4. Appendices
Twenty-two leading ecologists, geomorphologists and hydrologists attended a
workshop titled "Stream Habitat Assessment: Integrating Physical and Biological
Approaches", that was held at the University of Canberra on May 2-3, 2000 (Table
4.1). Broadly, the workshop was designed to provide the rationale and background
information upon which to build the physical assessment protocol. The specific
aims of the workshop were to:
- examine physical and biological approaches to the assessment of stream condition
currently in use in Australia;
- determine the critical parameters required for assessment of stream condition
from both a geomorphological and a biological perspective; and,
- determine variables that are easily measured in the field and which represent
critical parameters.
There were many tangible and some less tangible outcomes of the habitat assessment
workshop. The less tangible outcomes generally related to the formation of interdisciplinary
approaches to stream assessment and are summarised as follows:
- the workshop bought together geomorphologists, ecologists and hydrologists
to seek an interdisciplinary approach to physical assessment of stream condition.
As such, the workshop fostered dialogue that may result in advances in both
disciplines; and,
- the workshop highlighted that the topic of physical and chemical stream
assessment is complex and multifaceted, particularly when overlain with a
prerequisite of biological relevance.
The tangible outcomes of the workshop relate directly to the development of
a standardised physical and chemical assessment protocol. Three main topics
of concern arose from general discussion sessions and workshop presentations
on five existing stream assessment methods (River Habitat Audit Procedure, River
Styles, Index of Stream Condition, AusRivAS and Habitat Predictive Modelling).
These topics of concern were: study design issues, appropriate scale of focus
and identification of physical and chemical variables to use in the protocol.
A fourth issue that will need to be addressed is the overall choice of method
used to determine stream condition. These topics of concern are discussed individually
in the following sections.
Table 4.1 List of participants in the Habitat Assessment
Workshop
| John Anderson1 |
Judy Faulks |
Richard Norris5 |
| Rebecca Bartley |
Brian Finlayson |
Melissa Parsons |
| Andrew Boulton |
Kirstie Fryirs |
Mike Stewardson |
| Gary Brierley2 |
Chris Gippell |
Mark Taylor |
| Nerida Davies3 |
Bruce Gray |
Jim Thompson |
| Jenny Davis |
Kathryn Jerie |
Martin Thoms |
| Barbara Downes |
Tony Ladson4 |
Simon Townsend |
| Fiona Dyer |
Richard Marchant |
John Whittington |
| Wayne Erskine |
Leon Metzeling |
|
- Presented an overview of the River Habitat Audit Procedure
- Presented an overview of River Styles
- Presented an overview of Habitat Predictive Modelling
- Presented an overview of the Index of Stream Condition
- Presented an overview of AusRivAS
4.1.2.1 Study design issues
Some study design issues that need to be considered in developing a protocol
are:
- Comparisons between similar types of rivers will be an important aspect
of the physical and chemical assessment protocol. Thus, the protocol should
include an explicit method for dividing streams into homogeneous stream sections.
The River Habitat Audit Procedure (Anderson, 1993) and River Styles (Brierley
et al., 1996) are potential candidates for achieving this on a medium
to large-scale. However, if the Habitat Predictive Modelling approach (Davies
et al., 2000) is to be used in the standardised protocol, consideration
must also be given to the grouping of similar sites using small-scale physical
features. It may be possible to use the homogeneous stream section identification
techniques of the River Habitat Audit Procedure and River Styles to enhance
the formation of groups in Habitat Predictive Modelling.
- The geomorphological reference condition needs to be defined for a standardised
protocol. The definition of reference condition is particularly important
if Habitat Predictive Modelling is used, because this approach requires a
reference site database on which to build the model. The River Habitat Audit
Procedure, River Styles and the Index of Stream Condition are less reliant
on pre-defined reference conditions, and use post-sampling condition ratings
derived from knowledge of the 'best available' stream condition. Similarly,
the approach of the United Kingdom's River Habitat Survey was to identify
reference sites post-sampling, on the basis of criteria such as the occurrence
of rare or outstanding habitat features or a habitat quality assessment score
(Raven et al., 1998). Delineation of physical reference condition needs
to be examined in detail for the protocol, because this step is critical to
the process of assessing stream condition, as separate from merely describing
the physical characteristics of streams.
Some scale issues that need to be incorporated into the standardised physical
and chemical assessment protocol are:
- The design of the standardised physical and chemical assessment protocol
should pay close attention to both grain and extent. Extent is the overall
area encompassed by a study, and grain is the individual unit of observation
(Wiens, 1989). AusRivAS has a large extent (sites spread across States) but
a small grain (10m sweep net samples collected from habitats within reaches).
As a group, macroinvertebrates integrate a whole range of impacts occurring
over a range of temporal and spatial scales and thus, the grain size used
in AusRivAS is adequate for assessing the biological condition of individual
sites spread across the landscape. However, physical and chemical aspects
of stream condition have different properties to the biota and thus, the use
of the same grain and extent as AusRivAS may not be adequate for assessments
of physical and chemical condition.
- In addition to the scale of focus of the study design, the scale of focus
of measurement variables needs to be resolved. It is well accepted that there
is a hierarchical arrangement of physical features within river systems and
that processes operating on higher scales act to constrain processes operating
on lower scales (Schumm and Lichty, 1965; Schumm, 1977; Frissell et al.,
1986). Thus, physical features could be measured on a number of scales ranging
from catchments, to sections, zones, reaches, individual habitat units and
microhabitats. It may be best to match the scale of focus of the measurement
variables with the grain and extent of the study design. However, the arrangement
of river systems in a hierarchical formation suggests that factors operating
at scales 'in-between' the grain and extent may also be important for determining
physical and chemical stream condition. If the Habitat Predictive Modelling
approach is to be adopted as the overall method of assessment, it will be
necessary to measure a large number of large and local-scale physical features,
although other variables measured at other scales may also be incorporated
into the model. Conversely, the collection of variables at 'too many' scales
may complicate interpretations, add to field collection times and add little
to assessment of stream condition. Perhaps the best way forward would be to
examine the grain and extent of existing physical and chemical assessment
methods and then investigate the deviation of these scales from the ones currently
used in AusRivAS.
4.1.2.3 Identification of Physical and Chemical Variables to Use in the Protocol
Considerations for selecting the variables to include in the protocol are:
- When selecting potential variables for use in the protocol, the ease of
field measurement, conformity with rapid philosophies and the expertise required
to collect and interpret data will need to be considered. However, in eliminating
variables that do not meet these criteria, care needs to be taken that key
variables for the assessment of river condition are maintained in the protocol.
Additionally, consideration must be given to the practical application of
the protocol in the field. If it is to be conducted alongside AusRivAS sampling,
then realistically it can not take longer than one or two hours in the field
to collect data. However, if it is to be conducted as a separate exercise
from AusRivAS, then more field time can be incorporated because of the reduced
need for laboratory processing time.
- The current set of AusRivAS variables does not seem to fully encompass physical
influences on stream condition, because AusRivAS variables were chosen to
represent the physical environment for macroinvertebrates. In the protocol,
it will be necessary to include variables that are important to macroinvertebrates,
however, there are many additional variables to include that represent important
physical and geomorphological aspects of stream condition. A summary of physical
and chemical variables discussed at the workshop is given in Table
4.2.
4.1.2.4 Choice of method used to determine stream condition
Each of the methods presented at the workshop (Index of Stream Condition, River
Habitat Audit Procedure, River Style and Habitat Predictive Modelling) has the
potential to assess different aspects of stream condition. However, no single
method seems to fulfil all the requirements for a standardised physical and
chemical assessment protocol and as such, the relevant components will need
to be extracted from each method and incorporated into a new protocol. The suitability
of each method and the relevant components to incorporate into the protocol
will be discussed in Appendix 2.
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Validation of the Methodology. Department of Primary Industries, Queensland.
Brierley, G., Fryirs, K. and Cohen, T. (1996) Development of a generic geomorphic
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characterisation. Working Paper 9603, Macquarie University, Graduate School
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Davies, N.M., Norris, R.H. and Thoms, M.C. (2000) Prediction and assessment
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