Sustainable Rivers Audit
SRA Report 1
A report on the ecological health of rivers in the Murray-Darling Basin, 2004–2007
Peter Davies, John Harris, Terry Hillman and Keith Walker
June 2008
Prepared by the Independent Sustainable Rivers Audit Group for the Murray–Darling Basin Ministerial Council
SRA Report 1
Independent Sustainable Rivers Audit Group
Peter Davies John Harris Terry Hillman Keith Walker
June 2008
Published by Murray–Darling Basin Commission Postal Address GPO Box 409, Canberra ACT 2601 Office location Level 4, 51 Allara Street, Canberra City Australian Capital Territory
Telephone (02) 6279 0100 international + 61 2 6279 0100 Facsimile (02) 6248 8053 international + 61 2 6248 8053 E-mail [email protected] Internet http://www.mdbc.gov.au
For further information contact the Murray–Darling Basin Commission office on (02) 6279 0100
This report may be cited as: Davies PE, JH Harris, TJ Hillman and KF Walker 2008. SRA Report 1: A Report on the Ecological Health of Rivers in the Murray–Darling Basin, 2004–2007. Prepared by the Independent Sustainable Rivers Audit Group for the Murray– Darling Basin Ministerial Council.
MDBC Publication No. 16/08
ISBN 978 1 921 257 56 8
© Copyright Murray–Darling Basin Commission 2008
This work is copyright. Graphical and textual information in the work (with the exception of photographs and the MDBC logo) may be stored, retrieved and reproduced in whole or in part, provided the information is not sold or used for commercial benefit and its source SRA Report 1: A Report on the Ecological Health of Rivers in the Murray–Darling Basin, 2004–2007 is acknowledged. Such reproduction includes fair dealing for the purpose of private study, research, criticism or review as permitted under the Copyright Act 1968. Reproduction for other purposes is prohibited without prior permission of the Murray–Darling Basin Commission or the individual photographers and artists with whom copyright applies.
To the extent permitted by law, the copyright holders (including its employees and consultants) exclude all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this report (in part or in whole) and any information or material contained in it.
The contents of this publication do not purport to represent the position of the Murray–Darling Basin Commission. They are presented to inform discussion for improvement of the Basin's natural resources. iii
Dedication
Peter Wray Cullen AO 1943 – 2008
A visionary scientist and one of the architects of the Sustainable Rivers Audit iv
Contents
Dedication ...... iii Contents ...... iv Executive Summary...... ix Acknowledgements...... xiii 1. Introduction...... 1 1.1 Overview ------1 1.2 Program design ------1 1.3 Links to regional and national programs ------3 1.4 Links to international programs------3 1.5 Reporting schedule------3 2. The Audit Framework...... 5 2.1 Nature of the ecosystem ------5 2.2 Elements of the Audit ------6 2.2.1 Condition and Ecosystem Health ...... 6 2.2.2 Reference Condition...... 7 2.2.3 Reporting scale...... 7 2.2.4 Sample site selection...... 8 2.2.5 Sample frequency...... 8 2.3 Linking the Audit to ecosystem health ------8 2.3.1 Ecosystem components and Themes ...... 8 2.3.2 Data relationships and integration using Expert Rules...... 11 2.4 Reporting data in statistical terms ------14 2.5 Attributes of healthy and unhealthy systems------15 3. Themes ...... 18 3.1 Selection of Themes ------18 3.2 Hydrology ------18 3.2.1 Background...... 18 3.2.2 Data sources...... 19 3.2.3 Reference Condition for Hydrology ...... 20 3.2.4 Variables, metrics and indicators...... 20 3.2.5 Aggregation and integration methods for hydrology...... 24 3.3 Fish------25 3.3.1 Background...... 25 3.3.2 Sampling methods ...... 25 3.3.3 Reference Condition for Fish...... 26 3.3.4 Variables, metrics and indicators...... 26 3.3.5 Diagnostic metrics ...... 27 3.3.6 Aggregation and integration methods for fish...... 28 3.4 Macroinvertebrates ------29 3.4.1 Background...... 29 3.4.2 Sampling methods ...... 30 3.4.3 Reference Condition for Macroinvertebrates...... 30 3.4.4 Variables, metrics and indicators...... 31 3.4.5 Aggregation and integration methods for macroinvertebrates ...... 32 v
3.5 Proposed Themes ------33 3.5.1 Physical Form ...... 33 3.5.2 Vegetation...... 33 4. Operations...... 34 4.1 Introduction ------34 4.2 Sample Plans ------34 4.3 Sampling compliance ------35 4.3.1 Overview...... 35 4.3.2 Implications for the Fish Theme ...... 35 4.3.3 Implications for the Macroinvertebrate Theme ...... 35 4.4 Hydrology Theme ------36 4.5 Data management ------36 4.5.1 Data returns ...... 36 4.5.2 Data quality...... 36 4.5.3 Contextual analysis...... 37 4.6 Program management------37 4.6.1 Quality Assurance...... 37 4.6.2 Review of field sampling and analysis...... 37 5. Assessment of Valleys...... 40 5.1 Basin context------40 5.1.1 Ecosystem Health and Condition ...... 40 5.1.2 Rainfall and drought...... 40 5.2 Avoca Valley ------47 5.2.1 Hydrology...... 47 5.2.2 Fish ...... 49 5.2.3 Macroinvertebrates ...... 53 5.2.4 Ecosystem Health...... 57 5.3 Border Rivers Valley ------59 5.3.1 Hydrology...... 59 5.3.2 Fish ...... 62 5.3.3 Macroinvertebrates ...... 66 5.3.4 Ecosystem Health...... 70 5.4 Broken Valley ------72 5.4.1 Hydrology...... 72 5.4.2 Fish ...... 75 5.4.3 Macroinvertebrates ...... 79 5.4.4 Ecosystem Health...... 83 5.5 Campaspe Valley ------85 5.5.1 Hydrology...... 85 5.5.2 Fish ...... 88 5.5.3 Macroinvertebrates ...... 92 5.5.4 Ecosystem Health...... 96 5.6 Castlereagh Valley ------98 5.6.1 Hydrology...... 98 5.6.2 Fish ...... 100 5.6.3 Macroinvertebrates ...... 104 5.6.4 Ecosystem Health...... 108 5.7 Condamine Valley ------110 5.7.1 Hydrology...... 110 5.7.2 Fish ...... 113 5.7.3 Macroinvertebrates ...... 117 5.7.4 Ecosystem Health...... 121 vi
5.8 Darling Valley ------123 5.8.1 Hydrology...... 123 5.8.2 Fish ...... 125 5.8.3 Macroinvertebrates ...... 129 5.8.4 Ecosystem Health...... 133 5.9 Goulburn Valley ------135 5.9.1 Hydrology...... 135 5.9.2 Fish ...... 138 5.9.3 Macroinvertebrates ...... 142 5.9.4 Ecosystem Health...... 146 5.10 Gwydir Valley ------148 5.10.1 Hydrology...... 148 5.10.2 Fish ...... 151 5.10.3 Macroinvertebrates ...... 155 5.10.4 Ecosystem Health...... 159 5.11 Kiewa Valley ------161 5.11.1 Hydrology...... 161 5.11.2 Fish ...... 163 5.11.3 Macroinvertebrates ...... 167 5.11.4 Ecosystem Health...... 171 5.12 Lachlan Valley ------173 5.12.1 Hydrology...... 173 5.12.2 Fish ...... 175 5.12.3 Macroinvertebrates ...... 179 5.12.4 Ecosystem Health...... 183 5.13 Loddon Valley------185 5.13.1 Hydrology...... 185 5.13.2 Fish ...... 187 5.13.3 Macroinvertebrates ...... 191 5.13.4 Ecosystem Health...... 195 5.14 Macquarie Valley------197 5.14.1 Hydrology...... 197 5.14.2 Fish ...... 200 5.14.3 Macroinvertebrates ...... 204 5.14.4 Ecosystem Health...... 208 5.15 Mitta Mitta Valley------210 5.15.1 Hydrology...... 210 5.15.2 Fish ...... 212 5.15.3 Macroinvertebrates ...... 216 5.15.4 Ecosystem Health...... 220 5.16 Murray Valley, Lower------222 5.16.1 Hydrology...... 222 5.16.2 Fish ...... 225 5.16.3 Macroinvertebrates ...... 229 5.16.4 Ecosystem Health...... 233 5.17 Murray Valley, Central ------235 5.17.1 Hydrology...... 235 5.17.2 Fish ...... 238 5.17.3 Macroinvertebrates ...... 242 5.17.4 Ecosystem Health...... 246 vii
5.18 Murray Valley, Upper------248 5.18.1 Hydrology...... 248 5.18.2 Fish ...... 251 5.18.3 Macroinvertebrates ...... 255 5.18.4 Ecosystem Health...... 260 5.19 Murrumbidgee Valley ------262 5.19.1 Hydrology...... 262 5.19.2 Fish ...... 265 5.19.3 Macroinvertebrates ...... 269 5.19.4 Ecosystem Health...... 273 5.20 Namoi Valley ------275 5.20.1 Hydrology...... 275 5.20.2 Fish ...... 277 5.20.3 Macroinvertebrates ...... 281 5.20.4 Ecosystem Health...... 285 5.21 Ovens Valley ------287 5.21.1 Hydrology...... 287 5.20.3 Fish ...... 289 5.21.2 Macroinvertebrates ...... 293 5.21.3 Ecosystem Health...... 297 5.22 Paroo Valley------299 5.22.1 Hydrology...... 299 5.22.2 Fish ...... 301 5.22.3 Macroinvertebrates ...... 305 5.22.4 Ecosystem Health...... 309 5.23 Warrego Valley ------310 5.23.1 Hydrology...... 310 5.23.2 Fish ...... 312 5.23.3 Macroinvertebrates ...... 316 5.23.4 Ecosystem Health...... 320 5.24 Wimmera Valley------322 5.24.1 Hydrology...... 322 5.24.2 Fish ...... 325 5.24.3 Macroinvertebrates ...... 329 5.24.4 Ecosystem Health...... 333 6. Comparison of Valleys...... 335 6.1 Introduction ------335 6.2 Hydrology Theme ------335 6.3 Fish Theme------337 6.3.1 Species recorded...... 337 6.3.2 Numbers and biomass...... 341 6.3.3 Observed and predicted communities ...... 344 6.3.4 Condition indices ...... 347 6.3.5 Zone communities ...... 348 6.4 Macroinvertebrate Theme ------350 6.4.1 Families recorded ...... 350 6.4.2 Observed and expected communities ...... 352 6.4.3 Condition indices ...... 355 6.5 Correlation of Theme indices ------358 6.6 Ecosystem Health ------359 viii
7. Progress, Problems and Prospects...... 361 7.1 Progress and future development ------361 7.2 Audit framework ------361 7.3 Other issues------362 7.3.1 General ...... 362 7.3.2 Hydrology...... 362 7.3.3 Fish ...... 362 7.3.4 Macroinvertebrates ...... 363 7.3.5 Quality Assurance and Quality Control...... 363 7.3.6 Sampling and reporting frequency...... 363 7.3.7 Goals and targets ...... 364 8. References ...... 365 9. Appendices ...... 368 9.1 Appendix I: Expert Rules tables ------368 9.2 Appendix 2: Fish and macroinvertebrate sampling sites ------375
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Executive Summary The Sustainable Rivers Audit (SRA) is a systematic assessment of the health of river ecosystems in the Murray-Darling Basin. It is overseen by a panel of independent ecologists, the Independent Sustainable Rivers Audit Group (ISRAG), who are the authors of this report. The report provides assessments of ecosystem health for each of 23 major river Valleys, using data gathered in 2004–07, on hydrology, fish and macroinvertebrates. This is a first step toward analysis of trends, which will be a feature of later reports. The first in a triennial SRA series, the report also describes the framework of the SRA, its operation and options for future development.
The Audit Framework The SRA gathers quantitative information on environmental indicators in Valleys throughout the Basin. The indicators provide ‘windows’ on particular components of the river ecosystems, and are grouped as Themes. At this stage there are Themes for Hydrology, Fish and Macro- invertebrates. The data are acquired systematically using agreed protocols, with quality assurance. Within each Valley there are 1–4 Zones, defined in most cases by altitude. Sampling sites are located randomly within Zones, to enable unbiased statistical analyses and representative reporting. The indicators are combined to form quantitative measures of Condition for each Theme, and Theme Condition ratings are combined to assess Ecosystem Health. Condition assessments for each Valley are related to a benchmark called Reference Condition. This estimates the status of a component (for example, the fish community) as it would be had there been no significant human intervention in the landscape. Reference Condition is a benchmark representing the river ecosystem in good health, but is not a target for management. Condition is rated on a five-point scale from Good through Moderate, Poor, Very Poor to Extremely Poor, depending on how different the Theme components are from their respective benchmarks. The same scale is applied to Ecosystem Health.
Assessment of the River Systems
Assessments of Condition and Ecosystem Health for each of the 23 Valleys in the Basin are shown in the accompanying table. A severe drought has prevailed over the Basin during the Audit period. It is too soon to say how much this has affected fish and macroinvertebrate communities. It has also limited the availability of sampling sites in some Valleys. Hydrological Condition Hydrological data were available for 469 sites. For each site, five indicator values were calculated, representing changes in the flow regime due to human intervention. Site-based assessments of condition were made but, as sites were not randomly distributed, statistical comparisons at Valley and Zone scales were not possible. One third of all Valleys were rated in Good Hydrological Condition, and another third were in Moderate to Good Condition. Many of the sites in Poor Condition were in the lowland Zones of the major rivers. x
The Reference Condition for Hydrology is designed to include wet and dry periods. Condition assessments therefore, reflect the overall effects of the current level of development and water use within the Basin on the historical flow regime rather than that of the recent drought. Fish Condition Fish sampling at 487 sites yielded more than 60,600 individuals in 38 species, weighing more than 4 tonnes. Twenty eight of these were native, many of them small species, contributing 57% of individuals but only 32% of biomass. All fish were returned to the water after measurement (except for pest species in some States). Thirteen metrics were calculated from the sampling and Reference Condition data. Two indicators based on metrics for abundance, biomass and species composition were combined to derive the Sustainable Rivers Fish Index. Fish communities in the Paroo, Condamine and Border Rivers Valleys were in Moderate Condition, those in eight other Valleys were in Extremely Poor Condition. Those in the remaining Valleys were in Poor or Very Poor Condition. Communities in the northern Basin generally were in better Condition than those in the southern Basin. Native fish dominated by numbers in the Lower and Central Murray, Paroo and Warrego Valleys, and by biomass in the Paroo (78%), Darling (62%) and Borders River Valleys (60%). Golden perch were recorded in 21 of 23 Valleys, and Murray cod, Freshwater catfish and Silver perch were in 16, 7 and 5 Valleys, respectively. Alien species rivalled or outnumbered native fish in nine of the 23 Valleys, especially the Campaspe, Gwydir, Macquarie and Murrumbidgee Valleys. Three alien species, Carp, Eastern gambusia and Goldfish, were present in all rivers, and Redfin perch, Brown trout and Rainbow trout were also widespread. Carp were overwhelmingly dominant, being 87% of alien fish biomass and 58% of total fish biomass. In other words, Carp accounted for nearly six of every 10 kilograms of fish in the Basin. Native species were found in only 43% of Valley Zones where they were predicted to occur under Reference Condition. This illustrates the well-known decline of native fish in the Basin. The Darling Valley had the highest biomass of alien and native fish (16.8 kg/site), and the highest biomass of native species (10 kg/site). The Central Murray Valley was next most productive. The Paroo Valley was least productive, yielding 0.75 kg/site of alien and native biomass, although 78% of this was native fish. Macroinvertebrate Condition Macroinvertebrate samples taken from 773 sites included over 209,100 specimens of macro- invertebrates (invertebrates visible to the naked eye) in 124 families. They include leeches and worms, shrimps, snails, beetles, bugs and the young stages of dragonflies, midges and other insects. Two indicators based on the presence of families and the composition of communities (but not on estimates of abundance), were combined as the Sustainable Rivers Macroinvertebrate Index. Communities in the Border Rivers, Upper Murray and Paroo Valleys were in Moderate Condition, and those in the Avoca and Wimmera Valleys were in Very Poor Condition. The remaining Valleys were in Poor Condition. Twenty three families were recorded in all 23 Valleys. A number of families were rare, including 14 that were recorded at only one site each. The common families include many species that are tolerant of pollution and other human disturbances, and the rare ones contain sensitive species. xi
In general, the communities of Valleys in the northern Basin were in better condition than those in the southern Basin. In addition, upland Zone communities generally were in better condition than those in lowland Zones. Ecosystem Health Only the Paroo Valley was rated in Good Health. The Border Rivers and Condamine Valleys were rated in Moderate Health. Seven other Valleys were in Poor Health and 13 were in Very Poor Health. No Valley was rated in Extremely Poor Health. Of 62 Zones in 23 Valleys, two were rated in Good Health, eleven were in Moderate Health and the remaining 49 were in Poor (19 Zones), Very Poor (27 Zones) or Extremely Poor Health (3 Zones). Nine of 13 Upland Zones were in Very Poor or Extremely Poor Health. Valleys in the northern Basin generally were in better health than those in the south. Two of nine northern Valleys were rated in Very Poor Health, compared to nine of 14 southern Valleys. The three Valleys rated in Moderate or Good Health were in the northern Basin.
Progress and Prospects The Sustainable Rivers Audit is developing into an effective tool for surveillance of the Basin’s river ecosystems. The scope of the Audit is to be expanded by the addition of Themes for Vegetation and Physical Form, including floodplain environments. Both are at an advanced stage of development and will be included in SRA Report 2. Refinements to existing indicators (hence measurements of Condition) and Reference Condition are also progressing. Future reports will describe trends in condition and health. Sampling procedures in the Fish and Macroinvertebrate Themes were reviewed, and the findings will be used to refine methods and improve consistency between agencies. The Hydrology Theme experienced problems due to delays and data limitations. These issues prevented quantitative rating and comparisons of Valleys and Zones, and need to be resolved for SRA Report 2 in 2010– 11. ISRAG recommends that the SRA should be expanded to include floodplain and terminal wetlands, including those declared as Wetlands of International Importance under the Ramsar Convention and icon sites in The Living Murray initiative. These include the Lower Lakes and Coorong. ISRAG urges the establishment of management goals for river health, at Valley and smaller scales, across the Murray-Darling Basin. ISRAG sees these as essential for good natural resources management. The SRA could play a valuable role in development and in monitoring progress against them. xii
Condition and Ecosystem Health assessments for Valleys in the Murray-Darling Basin, 2004–07
Condition Ecosystem Valley Health Macro- Rank Hydrology Fish invertebrates
1 Paroo Good Good Moderate Moderate
2 Border Rivers Moderate Moderate Moderate Moderate to Good
2 Condamine Moderate Moderate Moderate Poor to Good
3 Namoi Poor Good Poor Poor
3 Ovens Poor Good Poor Poor
3 Warrego Poor Good Poor Poor
4 Gwydir Poor Moderate Poor Poor to Good
5 Darling Poor Poor Poor Poor
5 Murray, Lower Poor Poor Poor Poor
5 Murray, Central Poor Moderate Poor Poor
6 Murray, Upper Very Poor Moderate Extremely Poor Moderate to Good
6 Wimmera Very Poor Poor Poor Very Poor
Moderate 7 Avoca Very Poor to Good Poor Very Poor Moderate 7 Broken Very Poor to Good Very Poor Poor Moderate 7 Macquarie Very Poor to Good Very Poor Poor
8 Campaspe Very Poor Moderate Extremely Poor Poor
8 Castlereagh Very Poor Good Extremely Poor Poor
8 Kiewa Very Poor Good Very Poor Poor
8 Lachlan Very Poor Moderate Extremely Poor Poor to Good
8 Loddon Very Poor Moderate Extremely Poor Poor
8 Mitta Mitta Very Poor Good Extremely Poor Poor
9 Goulburn Very Poor Poor Extremely Poor Poor
9 Murrumbidgee Very Poor Poor Extremely Poor Poor to Moderate
xiii
Acknowledgements The Independent Sustainable Rivers Audit Group (ISRAG) wishes to record its appreciation of contributions from many dedicated, professional people. Don Blackmore, former Chief Executive, Murray-Darling Basin Commission, and Professor Peter Cullen, formerly at the University of Canberra, played key roles in establishing the SRA. The SRA Team at the Murray-Darling Basin Commission has provided executive support to ISRAG, facilitated and administered every facet of planning and operations and contributed to discussions. Present members include Dr Sharon Davis, Dr Robyn Johnston, Dr Michael Wilson, Frederick Bouckaert, Greg Long, Dr Mathew Maliel and Kara Boughton. Past members include Brian Lawrence, Dianne Flett, Philippa Bourke, Dr Craig Boys, Julie Coysh, Dr Damian Green, Leanne Wilkinson, Vic Hughes and Sue Pritchard. Special acknowledgements are accorded to former Program Manager Jody Swirepik and former Director Scott Keyworth, whose energy and enthusiasm were vital for the program in its formative stages. Wayne Robinson as biometrician has made major contributions to the design of sampling programs and analysis of data. Dr Steve Carter has been responsible for analyses related to Expert Rules. Mark Lintermans has advised on fish biology. Other invaluable contributions have come from consultants and advisors, notably Dr Chris Gippel, Dr Chris Walsh, Dr Rory Nathan and Dr Mike Reid. Members of the Sustainable Rivers Audit Implementation Working Group (SRAIWG) are too many to name individually, but all have played vital roles in administration and coordination of logistics and personnel in the State jurisdictions, and in developing and implementing the program. Advice from Dr Bruce Chessman and Dr Jean Chesson has been especially helpful. The MDBC Community Advisory Committee has been a strong supportor of the SRA and through its representation on SRAIWG has made valuable contributions. Members of the Hydrology, Fish, Macroinvertebrate and Quality Assurance Task Forces also are too many to mention, but they have provided expert advice and robust criticism in developing and supporting the respective Themes. It remains to thank Dr Wendy Craik, Chief Executive of the Murray-Darling Basin Commission, and Les Roberts, General Manager Natural Resources, for their continued support.
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1. Introduction
1.1 Overview The Sustainable Rivers Audit (SRA) is the most comprehensive assessment of river health ever undertaken in the Murray-Darling Basin. Observations are being recorded at many sites, using standardized protocols for sampling and analysis, to indicate and monitor the ecological condition and health of the Basin’s rivers. As its name suggests, the SRA is an audit, concerned with surveillance rather than measuring compliance with standards or targets. It reports on the status of the rivers using standardized, representative, quality-assured data gathered in a systematic manner, and is concerned with the signs of change rather than the causes. Where changes are indicated, the appropriate response may be to mount an investigation to determine the cause, however, this is not part of the SRA program itself. Now entering its fourth year, the SRA is an initiative of the Murray-Darling Basin Commission (MDBC), supported by partner governments in the Australian Capital Territory, New South Wales, Victoria, Queensland, South Australia and the Australian Government. Each contributes to the membership of an SRA Implementation Working Group (SRAIWG), which provides technical advice to program management and oversees field and laboratory work by agency staff. The SRAIWG advises the SRA Team at the MDBC, responsible for coordinating the program, processing data and providing executive support to other parties. There are also specialist Task- forces, responsible for development and implementation of Themes (Section 1.2). The scientific integrity of the SRA is overseen by a panel of ecologists, the Independent Sustain- able Rivers Audit Group (ISRAG). ISRAG reports through the MDBC to the Murray-Darling Basin Ministerial Council, hence the wider community. This report, prepared by ISRAG, presents a Basin-wide assessment of river health, based on data gathered in 2004–07.
1.2 Program design The SRA combines information about the status and trends of groups of environmental indicators, called Themes, in each of 23 Valleys in the Basin (Fig. 1.2-1). Themes related to Hydrology, Fish and Macroinvertebrates are now active, and two others, related to Vegetation and Physical Form, are under development. Each Theme represents a key ecosystem component (Section 2.3). Sampling sites in Valleys are located in Zones defined, in most cases, by altitude. The sites are distributed randomly within Zones, to enable statistical analyses and unbiased assessments and comparisons between times and places. Field data are processed in a series of steps leading to Metrics and Indices for each Theme in each Zone and Valley. The Indices represent the Condition of the ecosystem component described by the respective Theme, and the information from all Themes is combined by ISRAG to indicate Ecosystem Health at the Valley scale.
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Figure 1.2-1. The Murray-Darling Basin, showing the 23 Valleys sampled in the Sustainable Rivers Audit
To facilitate comparisons between Valleys, allowing for different background conditions, the SRA employs a concept of Reference Condition. This describes the patterns and processes that would be expected to prevail now had there been no significant human intervention in the landscape. It is open to some uncertainty, because it is estimated rather than measured, but it is a consistent benchmark for each Theme and Valley (and Zone) in the Basin. The design of the SRA incorporates flexibility and accessibility, in the spirit of adaptive manage- ment. Virtually all facets of the program are open to revision as more data are gathered, as environmental conditions change, and as ideas change. The data obtained by sampling or analysis are available to all interested parties, including the public, but the levels of detail, analysis, synthesis and interpretation needed by these parties may differ. With this in mind, the program is designed to provide information at several levels, from summary assessments of condition and health down to the ‘raw data’ for each Theme at different sites and times in each Valley. The raw data are inviolable, and there is a strong emphasis on quality control and quality assurance in data collection and handling. On the other hand, the metrics and indicators derived from the raw data, and the methods used to combine and report them, are open to revision. Without doubt, they will be refined in future. More information about the purpose and design of the SRA is accessible via the MDBC portal on the Internet
1.3 Links to regional and national programs The MDBC has a number of environmental programs, including the SRA, that are linked through an Integrated Basin Reporting process. The SRA contributes data to other programs, and the SRA Team in particular, has developed a sophisticated data-management and quality-assurance system that is being adapted for use in other programs. Related programs include the Native Fish Strategy, The Living Murray, the Northern Murray-Darling Basin Program, the River Murray Water Quality Monitoring Program and other programs concerned with managing risks to shared resources. The SRA contributes also to the operations of River Murray Water, including issues related to the Cap on water diversions. Other regional, state and national programs are linked to the SRA through shared methods, data, reports and conceptual frameworks. State programs include ‘State of the Environment’ reporting and monitoring, including the Environmental Health Monitoring Program in Queensland, the Monitoring, Evaluation and Reporting Program in New South Wales, the Index of Stream Condition in Victoria and the Tasmanian River Condition Index. At a national level, the SRA has links to the Framework for the Assessment of River and Wetland Health, the National Monitoring and Evaluation Framework for natural resources management and state of the environment reporting. There are links also to the CSIRO Murray-Darling Basin Sustainable Yields Project. Other synergies are developing. For example, the SRA is likely to contribute to planning by the new Murray-Darling Basin Authority.
1.4 Links to international programs Few countries have large-scale river condition assessment programs as sophisticated as the SRA. Criteria for selecting and developing metrics used in the SRA were developed from those used in the Environmental and Monitoring Assessment Program (EMAP) of the US Environment Protection Agency
1.5 Reporting schedule The SRA was initiated by the Murray-Darling Basin Ministerial Council in late 2000. A frame- work (Whittington et al. 2001) was trialled in an SRA Pilot Audit of four Valleys in 2002–03 (MDBC 2004a–e), and the program formally commenced in 2004. The SRA operates on six-year cycles, with the most comprehensive reports issued at the end of each cycle. Annual reporting is precluded by limited resources and the scope and logistic complexity of the program, but it may become possible in future. A further complication is that the Themes address ecological patterns and processes operating over different scales of time and space, and annual reporting may be more useful for some Themes (e.g. Macroinvertebrates) than others (e.g. Physical Form). Two kinds of reports are produced in each six-year cycle: • Implementation and Operations Reports are scheduled in Years 1-2 and 4-5. These are concerned mainly with data collection, processing and analysis and quality assurance. 4
They may contain updates about program operations and preliminary assessments of data, but not comparisons between Valleys. Such reports were issued in 2004–05 and 2005–06. • Audit Reports are scheduled at three-year intervals, and will provide assessments of Condition for each Theme and Ecosystem Health for each Valley. o SRA Report 1 (this report) is due in Year 3 (2007–08). It contains comparative data from one round of sampling in all Valleys, and a Basin-wide assessment for the three current Themes, but does not consider trends. o SRA Report 2, due in Year 6 (2010–11), will include Valley-based assessments and analyses of trends. It will include three cycles of sampling for macro- invertebrates and two cycles for fish and hydrology, plus one cycle for vegetation and physical form, and will comment on status and trends in Condition and Ecosystem Health. It is also likely to include assessments of physical form and vegetation. Later reports will become still more comprehensive as data from more Themes become available. Reports are submitted annually to the Murray-Darling Basin Ministerial Council in March-April, via the Murray-Darling Basin Natural Resource Management Committee and the MDBC. These reports are released publicly, with the Council’s sanction. SRA Reports 1 and 2 will also be distributed to State jurisdictions, for comment as appropriate. This report is SRA Report 1. It provides a Basin-wide assessment of river health, indicated by the Hydrology, Fish and Macroinvertebrate Themes, for 2004–07, and includes: • An introduction to the conceptual foundations and framework for the SRA; • An outline of SRA operations, including methods, compliance and quality assurance; • Assessments of Condition and Ecosystem Health for each Valley; • Comparisons between Valleys; and • A review of progress and plans for future development.
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2. The Audit Framework
2.1 Nature of the ecosystem For many years, rivers were thought of merely as drainage channels linking the land and sea. This idea changed as it became clear that they have their own distinctive, self-sustaining communities of animals and plants. They are now acknowledged as ecosystems, but are unusual in that there is less cycling of nutrients than in, for example a lake, because matter is continually swept downstream. The headwater streams in a river system support communities of bacteria, fungi and invertebrates that feed upon organic matter washed in from the catchment, including the wood, bark and leaves of plants. This material is progressively rendered to smaller particles that sustain communities further downstream. As the streams gather volume, and the gradient decreases, the communities begin to change in favour of photosynthetic plants, including phytoplankton. The changes are rarely a smooth progression; instead, rivers tend to be ‘patchy’ environments in which more-or- less uniform patches are separated by boundaries (ecotones) that provide diverse habitats for organisms, and thereby promote biological diversity. In rivers like the Murray, with well- developed floodplain communities, patches may be related to the frequency and duration of flooding. The ecotones between the channel and riparian zone, or between wetlands and woodlands, are biodiversity ‘hotspots’. The channel and floodplain are inseparable. The channel transports water, sediment and dissolved material, and is a corridor for dispersal of animals and plants. The floodplain receives water from the channel and stores, decomposes and reconstitutes organic matter as new organisms. The biological processes involved in transformation of organic matter are more complex than those involved in transport so that, for many groups of flora and fauna, most biodiversity resides in floodplain habitats rather than the channel. The hydraulic connections between channel and floodplain are controlled by the pattern of flow in the river. Flow also governs the physical landscape, from the nature of the sediments to the shape of the channel, and the associated communities of plants and animals. In ecology, these relation- ships are embraced by the Flood Pulse Concept (Junk et al. 1989), which likens seasonal and annual changes in flow to the ‘pulse’ of a riverine ecosystem. The rivers of humid, tropical and warm-temperate regions have a strong seasonal pulse that is similar from one year to another. In other regions, especially those with dry climates, seasonal and annual patterns are erratic, and irregular flood and drought ‘events’ are likely to dominate. In either case, the flood pulse has profound effects on the kinds of animals and plants that live in the river and on its floodplain. An erratic pulse, for example, is likely to favour organisms that are hardy (tolerant to drought), opportunistic (able to capitalise quickly on good conditions) and mobile (ready to disperse quickly to areas where conditions are favourable). These are typical attributes of many species of riverine flora and fauna in the Murray-Darling Basin. The hallmark of dryland rivers is variability in time (seasons, years, decades) and space (sites, reaches, valleys, regions). River management often reduces or redistributes this variability, with potentially serious consequences for the ecosystem. In the Murray-Darling Basin, rainfall varies from one year to the next, and from one place to another, depending on latitude, orography, vegetation, distance from the coast and other factors. The nature and intensity of human development in the Basin also varies within Valleys and regions. These sources of variability are 6 significant for the SRA because they mean that, in statistical terms, large numbers of samples are needed to describe Valley ecosystems, and to detect differences and trends over time. More information about the ecology of rivers in the Murray-Darling Basin is provided by Mackay and Eastburn (1990), Crabb (1997), Young (2001) and Breckwoldt et al. (2004).
2.2 Elements of the Audit
2.2.1 Condition and Ecosystem Health At first sight, the idea of Ecosystem Health is an appealing, intuitive way to describe the complex patterns and processes of an ecological system. It refers to the status of an ecosystem, with all its components, in terms of structure, integrity, vitality and function. Under close analysis, however, the idea becomes complicated, and it has generated a lot of discussion in the last 20 years (e.g. Hearnshaw et al. 2005). Ecosystems are conceptual entities, and may not correspond to discrete areas of land or water. They are unique in many respects, so that generalisations can be elusive and comparisons may be difficult. The ‘health’ of an ecosystem cannot readily be judged by comparison with a database indicating ‘normal’ ranges for different variables, as ecologists do not have access to the kinds of reference data that a medical practitioner does. Nor is an ecosystem reliant on a single central coordinating and controlling unit, like a brain or heart. Although parts of an ecosystem may be lost due to changes in the environment, or to invasions by alien species, the system is unlikely to ‘die’; rather, it is transformed into a different state. Riverine ecosystems especially are influenced by extreme events, like floods and droughts, that have no direct counterpart in human health. Further, as humans are part of ecosystems, ecosystem ‘health’ is influenced by a host of social, political and economic factors, as well as the properties of the environment itself. In the SRA, data are gathered on ecosystem components, represented by Themes (e.g. Hydrology, Fish, Macroinvertebrates) that are linked by ecosystem processes (e.g. carbon exchange, energy transfer, nutrient cycling). The capacity of an ecosystem component to support these key processes is referred to here as its Condition, described by structural and functional measure- ments. Information about the condition of one component alone is not sufficient; rather, it is necessary to integrate data for a number of components, depending on how many Themes are active. The process of combining data from the Themes is carried out by ISRAG, leading to assessments of Ecosystem Health for each Valley. It requires some professional judgement, because it is based on information from a limited number of Themes. The presently active Themes (Hydrology, Fish, Macroinvertebrates) are linked by key processes at a range of scales, and thereby reflect Ecosystem Health. Future assessments could be strength- ened by adding Themes to include floodplain wetlands and woodlands, measures of processes like recruitment (the accrual of reproductive individuals to populations) and the system’s capacity to recover from disturbance (resilience). Added Themes, and more frequent observations in some cases, would increase the range of spatial and temporal scales covered by assessments. Condition of ecosystem components in Valleys is determined from a suite of measurements within the respective Themes, using methods explained in Section 3. A numerical comparison of observed Condition and that expected under Reference Condition (Section 2.2.2) is called a Metric. Metrics are combined as Indicators, indicators are combined as Indices, representing Condition. By this means it is possible to measure differences between current Condition and Reference Condition without implying that they are necessarily ‘good’ or ‘bad’. A river ecosystem is deemed ‘healthy’ when its essential character (its native flora and fauna, for example) is maintained over time, notwithstanding disturbances due to human activities or the 7 vagaries of climate. In these circumstances, the ecosystem is resilient enough to withstand disturbances and to continue to support processes and supply resources. Its resilience depends on the degree and nature of exploitation or change, as well as inherent properties like biological diversity and patterns of water and sediment transport, at a range of scales. In future development of the SRA, serial measures of ecosystem components will be used to assess resilience, and thereby extend assessments of Ecosystem Health.
2.2.2 Reference Condition In the SRA, Reference Condition indicates the Condition that would be likely to prevail now had there been no significant human intervention in that region. It is a benchmark, and underpins spatial comparisons without confounding influences due to regional differences in climate, soils, topography, biogeography or other factors. The concept applies throughout the SRA, but the methods used to estimate it vary among Themes, depending on available knowledge (see Section 3). Historical data, expert knowledge and modelling are used where possible, but sometimes these may not be sufficient for reliable estimates of some variables. In addition, Reference Condition may be described at site, Zone, Valley or even regional scales, depending on the variable of interest and the available information. Observations on the current state of these less-certain variables may still be gathered and reported, and could become important later, as trends emerge. In time, the importance of Reference Condition in SRA assessments is likely to diminish as the emphasis shifts toward detecting change between successive assessments. Although Reference Condition represents a river ecosystem in good health, it is not a target for management. This would be unrealistic because true pristine conditions in the Murray-Darling Basin are neither desirable nor attainable, and human impacts are an inseparable part of ecosystems. Further, management targets are properly determined by integrating ecological values with social, cultural and economic ones.
2.2.3 Reporting scale The SRA reports primarily at the Valley scale. Within each Valley, Zones are defined in order to facilitate the assignment of sampling sites in areas that are ecologically similar. Typically, there are two to four Zones per Valley, except the Paroo Valley which has a single zone. As sampling sites are assigned randomly within Zones, Reference Condition also is defined at that scale. Site-scale observations are aggregated to provide Zone- and Valley-scale assessments for each of the Valleys. The SRA does not formally report at the site scale, unless there are exceptional circumstances (for example, some site-level data may be of interest to specific audiences). Valley- scale assessments are made by combining (aggregating) site- and Zone-scale assessments, weighted according to their respective proportions of total stream length. In most Valleys, Zones are defined by altitude as ‘lowland’ (0-200 m AHD), ‘slopes’ (200-400 m AHD), ‘upland’ (400-700 m AHD) and ‘montane’ (>700 m AHD). There are exceptions, however, for the principal rivers, the Murray and Darling. The Darling Valley is partitioned as Lower, Middle and Upper Zones, using geomorphic rather than altitudinal criteria. The Murray is divided into Lower, Central and Upper Murray Valleys, and the former two are divided into Lower, Middle and Upper Zones, with an added zone to include streams draining the eastern slopes of the Mt Lofty Ranges. In terms of altitude, these are ‘Lowland’ Zones, except the Mt Lofty Zone which is classed as a ‘Slopes’ Zone. The Upper Murray Valley has three altitudinal Zones (Slopes, Upland, Montane). 8
2.2.4 Sample site selection In the present Audit, sampling sites were restricted to river or stream channels. They did not include floodplain woodlands or wetlands, including most of the icon sites of The Living Murray program
2.2.5 Sample frequency Sampling in Themes acquires data for Valleys at different rates because, given the need to balance sampling frequency and available resources, only part of the work required for a full Audit can be completed in any one year. The full complement of Valleys is sampled every three years for the Hydrology and Fish Themes, and every two years for the Macroinvertebrate Theme. At least one complete round of data collection should occur for all Themes in each three-year SRA reporting cycle (this may be varied, however, for the proposed Physical Form and Vegetation Themes).
2.3 Linking the Audit to ecosystem health
2.3.1 Ecosystem components and Themes The SRA bases its reports on natural components of the river ecosystem as well as components that are responsive to human interventions in the landscape. Two related conceptual models serve to illustrate the scope of the Audit: • The River Ecosystem Function Model (Fig. 2.3-1) shows some of the links between ecosystem components and processes across channel and floodplain. It also identifies the 9
components addressed by the SRA Themes. Each Theme represents the Condition of a component, and is effectively a window on the ecosystem. • The Human Impact – Condition Response Model (Fig. 2.3-2) relates Themes to the effects of human interventions in the environment, linking the causes of change to their biophysical consequences, Condition and Ecosystem Health. The rationale for selection of Themes is further described in Section 3.1. In each Theme, variables for monitoring Condition have been selected according to criteria developed from those used in the EMAP program of the US Environment Protection Agency. These include considerations of conceptual relevance, the logistical feasibility of measurement and analysis, statistical confidence, variability and interpretability. In the SRA, the criterion of interpretability has been extended to include a capacity to estimate Reference Condition.
Channel Floodplain
Birds VegetationVegetation & Bats Aquatic Terrestrial Frogs Large Trees Invertebrates Hydrology Clarity Hydrology Nutrient status Turbidity Temp Understorey TN, FRP, TN NOx, NH4 Reptiles High Flows Microbes
DOM Ground Cover Volume
Benthic R, GPP Macrophytes Seasonality Benthic algae Phytoplankton Macrophytes MPB & microbes Low Flows Water column R, GPP
Seed Bank Zero Flows MacroinvertebratesMacroinvertebrates Zooplankton Max Spell Littoral / Riffle Litter Macro, Mega Invertebrates POM Fish Fish Vertebrates (Fish) LWD LWD
Physical Form Array of Types Reach Condition
Figure 2.3-1. River Ecosystem Function Model showing components and processes in a channel-floodplain ecosystem. Components addressed by SRA Themes are shown as ‘windows’ (in grey) on the ecosystem. Active themes: Macroinvertebrates, Fish, Hydrology; Proposed Themes: Physical Form, Vegetation. Interactions between components are shown as arrows. 10
Vegetation •Fish • Macroinvertebrates • Hydrology •Physical Form • •Physical Biophysical Condition components: key of Status
measured as
Hydrology and hydraulics and Hydrology changes Population • impacts species Alien • Consequences • Geomorphology • quality Water • Biophysical
produces
regime
Alien speciesAlien spread Sediment regime Sediment and abundance Flow regime Flow regime Climate and substrate Nutrient Connectivity Mechanisms • • • • • • Changes in: Changes • regime Temperature • regime Fire • form Channel
via
’
Chemical application Chemical Grazing, cropping, cropping, Grazing, afforestation and leves Water cycle Water • • Regulation • improvement ‘River • Incidental Human Causes Use: Resource Water • impoundments Barriers, • and transfer Abstraction Change: Use Land • Clearing • • alienation Floodplain • Intentional : change Climate • Thermal • : introduction Species
Figure 2.3-2. Human Impact – Condition Response Model linking human causes of changes in riverine environments to ecosystem components. Components are equivalent to SRA Themes, shown on the right 11
2.3.2 Data relationships and integration using Expert Rules The steps involved in processing SRA data are illustrated in Figure 2.3-3. Sample site selection and sampling protocols, data entry, management and analysis are guided by processes developed by the SRA Team (Section 4). The data are defined and integrated as follows: • Primary data are field observations of variables (e.g. counts, measurements) recorded from individual samples and validated by quality control. In the Hydrology Theme, they may include modelled data. They may be accompanied by statistical summaries, providing derived data. An example is the names of fish species present at a site, leading to a derived statistic representing the number of species recorded. • Metrics represent the difference between an observation and its estimated value under Reference Condition. They are calculated from primary and/or derived data, from both observed (current) and Reference Condition. An example is the OE (observed: expected) ratio for fish, or the number of fish species expected under Reference Condition for a Zone that is actually observed at a site in the Zone. • Indicators are derived by integrating two or more Metrics using Expert Rules (see below). Generally, they are monotonically related to Condition. They may be ordinal numbers (rank assessments), and may involve comparisons with Reference Condition. Values range between 0–100. An example is ‘Expectedness’, which combines three metrics to yield information about the ‘expected’ species in a Zone. • An Index is an integrated value for Condition, derived by integrating two or more Indicators, using Expert Rules (see below), and aggregated for reporting at Valley- and Zone-scales. An example is the Sustainable Rivers Fish Index (SR–FI), which combines the ‘Expectedness’ and ‘Nativeness’ Indicators to represent the Condition of the fish community (Section 3.3.4). The diverse audience for the SRA requires results at various levels of detail (Fig. 2.3-3). To this end, the Audit data are preserved as a complete set of primary data, and as metrics, indicators and indices. Indicators and indices are derived from metrics using ‘Expert Rules’, a computational process based on ‘fuzzy logic’ (e.g. Negnevitsky 2002). This approach avoids the need for sharp, artificial boundaries between categories of assessment. Another virtue is that the process of assessment is transparent and open to review in the light of new knowledge. Still another is the ability to integrate independent kinds of assessments in ways that cannot be achieved by simple summation. 12
Data collection Estimated using standardized protocols Reference Condition
Condition and Health ISRAG assessments from all available data Ministerial Council rating MDBC Theme Index Community Indicators and Indices from Metrics by Expert Rules Indicators
Metrics Metrics Managers from Primary Data and Reference Condition Integration of Information Integration Derived Statistics
Scientists Primary Data Primary Data from each site
Level of detail Figure 2.3-3. Stages in processing information in the SRA, from primary data to assessment of health
The rules were developed initially by ISRAG, then encoded using the Fuzzy Logic Toolbox in the computer program MatLab® (The Mathworks Inc., USA). They were used at three levels: (1) Indicator Expert Rules determine the values of indicators from metrics (Hydrology and Fish Themes only); (2) Index Expert Rules determine the values of indices from indicators (Hydrology, Fish and Macroinvertebrate Themes); and (3) Health Expert Rules determine Ecosystem Health from all Theme indices. This approach requires judgements, based on ‘expert opinion’, of the relative contributions of each metric, indicator or index to the integrated result. In particular, assessments of Ecosystem Health required judgements about the links between Themes. For example, ‘Poor Condition’ of Macroinvertebrate and Fish (and potentially Vegetation) communities would logically indicate poor health, whether or not Hydrology (and potentially Physical Form) is ‘Poor’. If hydrological (and/or geomorphological) Condition were compromised, but biological Condition was not, the health of the system is at risk, perhaps with time-lagged biological responses to changes in the physical environment. In ISRAG’s view, ecological health is indicated mainly by biological changes caused by changes in physical drivers, subject to human impacts. Thus, Fish and Macro- invertebrate Condition have more influence on the Ecosystem Health rating than the Hydrology Condition. In addition, Fish Condition has more influence than Macroinvertebrate Condition, as fish are sensitive over a wider range of temporal and spatial scales than are most macro- invertebrates. The Expert Rules used to integrate assessments of Ecosystem Health are shown, in compact form, in Table 2.3-1, and the complete sets of rules used at the levels of indicators, indices and Ecosystem Health are tabulated in Appendix 1. It was intended that Ecosystem Health Index (SR-EH) scores would be derived for the Valleys by applying the Health Expert Rules to numerical data from the three active Themes. This was 13 precluded by the inability to spatially aggregate data from the Hydrology Theme for this report (see Section 3.2.2), and it was necessary to use Bands (Sections 2.4, 2.5) in place of numeric scores. Nevertheless, the rules were still used to support health assessments.
Table 2.3-1. Expert Rules in Ecosystem Health assessment. Values of the Ecosystem Health Index (SR–EH) are determined by combinations of Theme Condition Indices, shown here as Condition Ratings. The indices have different weightings, so that SR–EH scores are not derived by simple summation. These rules are used by ISRAG to support assessments in terms of the Labels shown at right. See further Appendix 1.
Condition Rating Ecosystem Health
Macro- Fish Hydrology SR-EH Label invertebrates Good Good Good 100 Good Good Good Poor 93 Health Good Good Extremely Poor 85 Poor Good Good 75 Good Poor Good 75 Poor Good Poor 69 Moderate Good Poor Poor 69 Health Good Poor Extremely Poor 63 Poor Good Extremely Poor 63 Poor Poor Good 53 Good Extremely Poor Good 50 Extremely Poor Good Good 50 Poor Poor Poor 47 Poor Good Extremely Poor Poor 45 Health Extremely Poor Good Poor 45 Poor Poor Extremely Poor 43 Good Extremely Poor Extremely Poor 40 Extremely Poor Good Extremely Poor 40 Poor Extremely Poor Good 28 Extremely Poor Poor Good 28 Extremely Poor Poor Poor 24 Very Poor Poor Extremely Poor Poor 24 Health Poor Extremely Poor Extremely Poor 20 Extremely Poor Poor Extremely Poor 20 Extremely Poor Extremely Poor Good 5 Extremely Poor Extremely Poor Poor 3 Extremely Poor Extremely Poor Extremely Poor Extremely Poor 0 Health
14
2.4 Reporting data in statistical terms In this report, the score for a Valley-scale index (or indicator) is the average of scores for Zones in the Valley, weighted according to their relative stream lengths. It is thereby spatially aggregated. Most SRA indices have skewed (asymmetrical) distributions, and the appropriate statistic to indicate average values is the median (the average of position) rather than the arithmetic mean (the average of values). The more skewed the data, the greater is the difference between median and mean. The median is the preferred statistic because it is least sensitive to extreme values. For Zones, therefore, values are calculated from site data as medians rather than means. The calculated median is an estimate of the ‘true’ value that would have been obtained if all possible sites had been sampled. The most appropriate way to indicate the reliability of an estimate in this case is to determine the 2.5 and 97.5 percentiles of 2000 random samples of the original site data. This ‘boot-strapping’ procedure yields confidence limits (CL) for the calculated median, specifying a range in which we can be 95% sure that the ‘true’ median lies. This procedure is repeated anew for each index and indicator, at either Valley- or Zone-scale. It is convenient to specify the lower and upper 95% confidence limits in parentheses. For example, an index might have a median of 50 (CL 35–70), indicating an estimated value of 50 and a 95% probability that the ‘true’ median lies between 35 and 70. Comparisons between indices should take account of the associated confidence intervals. For example, a wide confidence interval indicates a high degree of variation among sites in the Valley or Zone for which the median is calculated. Thus, medians of 40 and 50 may not be different, in statistical terms, if the associated confidence limits overlap. In reporting SRA indices and indicators, the following notations apply:
• Median index and indicator scores are reported with lower and upper 95% confidence limits in parentheses. • The median score is assigned to a Band, according to Table 2.4-1. • If the associated confidence limits extend into one or more higher Bands, a (+) qualifier is added to the assigned Band. If they extend into one or more lower Bands, a (–) qualifier is added. If they overlap higher and lower Bands, a (±) qualifier is added. The same qualifiers are applied to a Label assigned to each Band, as in Table 2.4-1. Labels are used, for example, in the ‘boxed’ remarks that preface assessments of Condition and Ecosystem Health (Section 5). To illustrate: a SR–FI score could be reported as 50 (CL 35–70), indicating a Large (±) Difference from Reference Condition. In this case, the qualifier shows that the confidence limits extend into one or more adjacent score Bands, as Table 2.4-1 will confirm. 15
Table 2.4-1. Bands and Labels applied to assessments of Condition and Ecosystem Health
Score Band Label range Difference from Theme Condition Reference Condition or Ecosystem Health
80–100 Near Reference Condition Good 60–79 Moderate Difference Moderate 40–59 Large Difference Poor 20–39 Very Large Difference Very Poor 0–19 Extreme Difference Extremely Poor
Part of the rationale for distinguishing these ranges (hence Bands, Labels) is as follows: • Up to 20% fewer fish species and macroinvertebrate families, and reductions in high- and low-flow and other hydrological variables, relative to Reference Condition, are probably not significant ecological changes in the present context. This makes allowances for the uncertainties in estimating Reference Condition for each Theme, and for the inherent variability of the system. • A 20–40% reduction in these variables is likely to indicate significant disruptions to ecological processes. • Greater changes are likely to represent correspondingly greater disruptions to ecological processes.
2.5 Attributes of healthy and unhealthy systems In ecology, as in human biology, it is often easier to define an unhealthy system than a healthy one. Health cannot be measured directly; instead, we employ a variety of surrogate measurements and other observations that indicate the system’s capacity to support key processes (e.g. carbon exchange, nutrient cycling, energy transfer, sediment transport, recruitment), structural components (e.g. communities, populations) and its resilience. These observations must be integrated to provide a holistic assessment of ecosystem health. An immense variety of observations might be monitored. Ecosystems are complex, dynamic systems that combine the properties of their living and non-living constituents with ‘emergent’ properties, like diversity and resilience, that are attributes of the system rather than its components. One approach to monitoring health is to look for detrimental changes in components and processes that are sensitive to various kinds of disturbances over a range of scales in space and time. For example, losses of native flora and fauna are a form of imbalance, and the effects are compounded when these are replaced by alien species. Another approach is to monitor key components that represent the products of ecological processes operating over a range of scales. Both approaches are consistent with the path followed in the SRA (Section 2.3). A healthy ecosystem (Section 2.2.1), which may include human communities, is seen as one whose essential character and functionality are maintained over time, despite disturbances due to resource exploitation, changes in climate and other external agencies. This does not mean that the system is 16 stable—in the Murray-Darling Basin, as in all big river systems, climatic variability leads to naturally wide variations in ecological patterns and processes. The variability apparent in small- scale biophysical processes also is significant, and should not be dismissed as noise. An unhealthy system is one substantially changed from its natural state, typically with losses in structural complexity, vigour, resilience and the efficiency of nutrient cycling. It may have lost and/or gained species, it may be affected by environmental changes (e.g. salinisation), or its resources may be intensively exploited (e.g. diversions of water for irrigation). None of these factors is inherently unhealthy, but may become so if they exceed the resilience of the system. The differences between ‘healthy’ and ‘unhealthy’ systems, then, may be matters of degree (e.g. the numbers of species lost, relative to those present originally). In the SRA, the process of assessment leads to five categories (Bands) that express the Condition of ecosystem components (Themes) in terms of differences from Reference Condition (Section 2.2.1). The Bands have corresponding Labels, used by ISRAG to describe assessments of Condition and Ecosystem Health. Table 2.5-1 illustrates some of differences between healthy and unhealthy ecosystems, as might occur in the Murray-Darling Basin.
Table 2.5-1. Symptoms of healthy and unhealthy river ecosystems, as might occur in the Murray-Darling Basin
Healthy Unhealthy Assessed Feature Ecosystem Ecosystem by SRA?
Flow regime includes floods and Flow regime is altered in ways that droughts of diverse magnitude and limit over-bank flows and isolate timing, across seasonal, annual and channel and floodplain for long Yes, as in the channel inter-annual and decadal scales, periods. Channel has instream flow regime in ensuring surface water connections barriers (e.g. dams, weirs) that Hydrology Theme. between channel and its floodplain impede up- and down-stream Connectivity between wetlands and woodlands. In lowland Connectivity, dispersal by aquatic plants and channel and floodplain regions, channel with few or no animals, including fish. Floodplain to be included through flow regime instream barriers to impede up- and fragmented (e.g. land clearing, use of GRADFLOW down-stream dispersal by aquatic urbanization, agricultural and from hydraulic plants and animals, including fish. development) in ways that impede data in Hydrology Floodplain allows dispersal of dispersal of terrestrial species along Theme. terrestrial plants and animals river corridor. Reduced connectivity laterally and along river corridor. with catchment. High connectivity with catchment.
Not measured at Balance of erosion and sediment- Channel and floodplain show present. To be ation is disturbed, leading to Sediment periodic erosion or sedimentation, measured using persistent catchment erosion, bank regime but these are balanced so that in the SEDNET and other collapse, siltation or other signs of long-term the system is ‘stable.’ indicators in proposed instability. Physical Form Theme.
Alien species of flora and fauna Yes, as fish species Native species of flora and fauna dominant; native species reduced or and macroinvertebrate Biodiversity persist; alien species scarce or absent. In more extreme cases, total families. Also planned absent. species and community diversity for Vegetation Theme. declines. 17
Healthy Unhealthy Assessed Feature Ecosystem Ecosystem by SRA?
High efficiency of bioavailable Low efficiency of bioavailable nutrient cycling on floodplain and in nutrient cycling on floodplain and in channel. Storage, transformation Nutrient- and channel. Lower biodiversity, trophic and uptake of carbon and other complexity and connectivity causing carbon- nutrients optimised by natural reduced transformation and uptake No. cycling diversity, trophic complexity and of carbon and other nutrients. Lost efficiency connectivity of biophysical efficiency dictated mainly by human components. Lost efficiency dictated impacts and high flows. Substantial mainly by high flows. Minimal ‘leakage’ of bioavailable nutrients. ‘leakage’ of bioavailable nutrients.
Populations of plants and animals, Populations of plants and animals, especially long-lived species (e.g. especially long-lived species (e.g. river red gum, Murray cod), fail to No, but planned for river red gum, Murray cod), recruit sufficiently often to maintain Fish and Vegetation Recruitment reproduce and recruit (survive to numbers across a range of age Themes by next full maturity) sufficiently often to classes. Populations may contain Audit report. maintain numbers across a range of disproportionate numbers of young age classes. or old individuals.
Yes, for selected System retains overall character System undergoes major changes in components, by despite changes in climate or levels character following changes in planned analyses of Stability of resource exploitation. climate or levels of exploitation. trends over time and Components and processes remain Components and processes integration across intact. radically altered. Themes.
Some or all communities lack Communities recover after capacity to recover original numbers disturbance (e.g. fire, drought, flood, Yes, by analysis of and distribution following pollution). Diversity of components trends in components disturbance. ‘Weed’ species may Resilience (e.g. species, habitats) and scales of over time, and by proliferate. Diversity of components processes maintained (e.g. assessment of and processes decreases (e.g. recruitment, rates of channel recruitment. substantial loss of species, less change). recruitment).
Levels of exploitation outstrip No, but could come No exploitation, or level of capacity of the system to recover; under MDBC Utility exploitation within the capacity of utility of river resources for humans Integrated Basin the system to recover. is reduced. Reporting.
18
3. Themes
3.1 Selection of Themes There are three active SRA Themes (Hydrology, Fish, Macroinvertebrates), and two others (Physical Form, Vegetation) under development. The Hydrology Theme includes measures of ecologically-significant aspects of the flow regime, including volume, variability, extreme flow events and seasonality. The Fish Theme includes measurements of fish numbers, biomass and community composition. The Macroinvertebrate Theme describes the occurrence of macro- invertebrate families at each site, and includes measures of community composition and sensitivity to disturbance. From 2008, the Hydrology Theme will be broadened to integrate channel and floodplain assessments. The same will apply to the new Vegetation and Physical Form Themes, as they are implemented. Themes are ‘windows’ on Condition and Ecosystem Health. They include variables that are readily measured, represent ecological roles at a range of spatial and temporal scales and are sensitive to river-ecosystem ‘drivers’ like water and sediment transport. Other reasons for this particular complement of Themes are: • Hydrology is a driver in all river ecosystems. The flow regime transports materials in suspension and solution and sustains aquatic and terrestrial organisms in channel and floodplain environments. It is sensitive to short- and long-term human interventions, and links the ecosystem to the regional landscape. • Macroinvertebrates are a large part of aquatic biodiversity and a food resource for fish and other fauna. They contribute to carbon and nutrient processing, are sensitive to natural changes and human disturbances over the short- to medium-term, and are readily sampled. • Fish are near the top of the aquatic food chain and are sensitive to environmental changes in the short- to long-term. They are a food resource for birds and, are well-known and valued by humans. • Vegetation (proposed) is part of aquatic and floodplain biodiversity, a habitat and food resource for plants and animals and a source and sink for carbon and other nutrients. Vegetation in channel and floodplain habitats is sensitive to natural changes and to human disturbances in the short- to long-term. • Physical Form (proposed) is another ecosystem driver, and is sensitive to human intervention in the short- to long-term. The geomorphic environment provides habitats for biota, and sources and sinks for materials transported by the river. More information about the existing and proposed Themes is provided below.
3.2 Hydrology
3.2.1 Background Hydrology defines the quantity and spatial and temporal distribution of water in the system. It is a natural driver of river form and function, and is often directly modified by human interventions. It provides sensitive measures of Condition, a means for comparisons between rivers and a context 19 for observations of ecosystem components like fish, vegetation and macroinvertebrates. It governs the transport of water and material, connectivity between components, the quality and extent of habitat, and it provides cues for biological processes (e.g. reproduction, migration). The Hydrology Theme is a natural complement for the proposed Physical Form Theme. Although it is presently focused on changes in the flow regime, derived from discharge records, aspects of hydraulics, connectivity and the floodplain water regime are planned for inclusion in future SRA reports.
3.2.2 Data sources At this stage in development of the Hydrology Theme, assessments are limited to parts of the drainage network (mainly high-order streams and rivers) for which there are models. As data become available from other sources, reaches from the upper catchments will be incorporated and the effects of land-use (e.g. farm dams), ground- and surface-water interactions and climate change will be included. This should commence in the next three-year Audit cycle, 2008–10. Hydrology Theme assessments for this report were based on data from the following flow models: the Integrated Quantity–Quality Model (IQQM: NSW, Qld), MSM-BIGMOD (for the Murray and Lower Darling channels: MDBC) and the REsource ALlocation Model (REALM: Vic.). Data for Valley sites were supplied by State jurisdictions and the MDBC, as follows: • Victoria: Avoca, Broken, Campaspe, Goulburn, Kiewa, Loddon, Mitta Mitta, Ovens, Wimmera • New South Wales, Australian Capital Territory: Border Rivers, Castlereagh, Darling, Gwydir, Lachlan, Macquarie, Murrumbidgee, Namoi • Queensland: Border Rivers (same data supplied by NSW, plus Moonie River), Condamine, Paroo, Warrego • MDBC: Upper, Central and Lower Murray Valley sites. The data were for different periods of modelled record, thus: • Data from Victoria were for 11–53 years of record, and typically 15–30 years • Data from New South Wales and the Australian Capital Territory were for 80–117 years of record, and typically more than 110 years • Data from Queensland were for 111–117 years of record • Data from MSM-BIGMOD (MDBC) were for 111 years of record (1895–2006). Data were derived for current and Reference Condition scenarios, for the same time periods (a Reference Condition scenario includes no infrastructure, no diversions or transfers: see Section 3.2.3). Current scenarios for Queensland (Border Rivers, Condamine, Paroo, Warrego Valleys) were modelled with all licensed offtakes fully utilised, and current scenarios for all other Valleys represent actual licensed current demands, per State agency hydrological models. Modelled flows for Victorian rivers (only) included the effect of farm dams in estimating Reference Condition. Hydrological data were not available for the entire drainage network, or for all reaches in the modelled network. Sites were selected by State agencies to be representative of flow regimes in the Valley, but generally at critical points from a water-management perspective (e.g. inflows to reservoirs, offtakes, tributary inflows). As the sites were not randomly chosen, statistical analyses were not possible. Spatial aggregation was also precluded because it was not possible to determine accurately the spatial domain of each site (the up- and/or down-stream area to which the data applied). Rather, domains varied according to the proximity of sites to major infra- structure or abstraction/transfer points. 20
The data supplied therefore, do not comply with the design requirements of the SRA which specify randomly-allocated, spatially-representative data for sites or reaches. The outcome was that indicators could be calculated for sites, but not aggregated to Zone- or Valley-scale, and evaluations of the hydrological condition of each valley were limited to qualitative evaluations based on site scores. This will be rectified in future SRA reports. In 2007–08, CSIRO commenced analyses of Basin-wide hydrological data through the Murray-Darling Basin Sustainable Yield Project (MDBSYP), deriving estimates of water yield and movement, accounting for links between surface- and ground-water, catchment land management (e.g. forestry, farm dams) and the projected effects of climate change. The assessments in MDBSYP are fundamentally different from those in the SRA: MDBSYP is forecasting changes in water yields that may occur under future scenarios of climate change, whereas the SRA is intended to evaluate flow-regime changes caused by human interventions, using ecologically-significant indicators. Both approaches, however, are based on similar modelled data, and future links between the two are under discussion.
3.2.3 Reference Condition for Hydrology Reference Condition for Hydrology is estimated using models run under assumptions of no direct human influence on water management (that is, with storages, diversions and inter-valley transfers set to zero). The effects of farm dams, reafforestation, land clearing, groundwater extraction and other land management activities, will be incorporated when they can be quantified. The models cover a minimal period of 15 years, and are run for each site, covering the same period of record as for the current scenario. Current levels of major water resource development were assessed for each Valley, with flows and diversions determined from gauging data. Major developments included large dams, offtake channels, surface water extraction for agricultural and urban use and inter-valley transfers (e.g. Snowy Mountains Scheme). The influence of each development was removed in each model, providing data to indicate Reference Condition. The influences of major dams, irrigation systems, irrigation and urban extractions and inter-basin transfers were removed in all models, but the influence of farm dams was removed in Victorian models only. The influences of groundwater extractions, waste-water treatment plant inflows, land-use changes and small, non-consumptive offtakes for fish farms or small hydro-electric systems were removed in some Valleys. It is intended that these factors will be incorporated consistently across the Basin for reporting in SRA Report 2. In the past decade, river flows in most of the Basin have been much lower than historic averages, and records for the last 20-30 years contain more low-flow years than those that span a century or more (Section 5.1.2). This is partly compensated by the nature of flow data used in the SRA— comparisons between current and Reference Condition—but important questions remain about the best means to account for future climate change.
3.2.4 Variables, metrics and indicators The Hydrology Theme employs metrics developed from variables used in the SRA Pilot Audit assessment for hydrology (MDBC 2004c), later included in the Flow Stressed Ranking (FSR) procedure developed by Sinclair Knight Merz (SKM 2004, 2005). A large suite of potential variables was reduced, mainly by minimizing redundancy (co-linearity) in the information they contain. 21
Potential metrics representing the hydrological status of rivers from an ecological perspective were reviewed in light of this analysis. Five indicators and seven corresponding metrics were selected, each indicating changes between current and Reference Condition: • Changes in High-Flow Events Indicator (HFE): High-Flow Metric, HF = Change in magnitude of high flows • Changes in Low- and Zero-Flow Events Indicator (LZFE) : Low-Flow Metric, LF = Change in magnitude of low flows Zero Flow Metric, PZ = Change in proportion of time with no flow • Changes in flow Variability Indicator (V): Monthly Variation Metric, CV = Change in coefficient of variation of monthly flows • Seasonality Indicator (S): Seasonal Period Metric, SP = Change in timing of minimum and maximum flows • Changes in Gross Volume Indicator (GV): Mean Annual Discharge Metric (MNAQ) Median Annual Discharge Metric (MDAQ). The latter two metrics have no direct counterparts in the FSR procedure. Metric values range from 0–100, where 100 indicates no change (equivalent to the Reference Condition value). In keeping with the FSR analyses (SKM 2004, and SKM 2005), all metrics were derived using monthly flow data, with the obvious exception of the two annual discharge metrics. The relative independence of the metrics simplifies their aggregation, using Indicator and Index Expert Rules (Appendix 1), to determine the SR Hydrology Index. Their ecological relevance, and methods of calculation, are explained below (and further in SKM 2005: Appendix C): 1. High-Flow Metric (HF) HF indicates changes in the magnitude of high flows from Reference to current conditions. Flood flows determine maximum depths, velocities and shear stresses. They drive fluvial geomorphic processes, transporting and depositing sediment and changing channel shape, and may act as a ‘disturbance’, removing vegetation and other organic matter and re-setting the processes of succession. Reduced flood flows can mean fewer over-bank flows, limiting connectivity between the channel and floodplain. Populations of many native species of flora and fauna recruit on a large scale during high-flow periods. HF is the mean of the highest and second highest monthly flows (top 12th and second top 12th flows, or 8.3rd and 16.7th percentiles), thus:
HF= (HF8.3 + HF16.7) /2 where HF8.3 is the range-standardized high-flow index based on the 8.3% exceedance flow, from
HF8.3 = 1 – 2 × | Pile(Q8.3r) – Pile(Q8.3c) | where
Q 8.3c = Current 8.3% exceedance flow (ML) Q 8.3r = Reference 8.3% exceedance flow (ML) Pile(Q8.3c) = Proportion of years that the 8.3rd percentile current flow is exceeded by the annual 8.3rd percentile Reference flow
Pile(Q8.3r) = Proportion of years that the 8.3rd percentile Reference flow is exceed- ed by the annual 8.3rd percentile Reference flow 22
The range-standardised high-flow index based on the 16.7% exceedance flow, HF16.7, is calculated in a similar way. 2. Proportion of Zero Flow Metric (PZ) PZ compares the proportions of months with zero flow under Reference Condition and current conditions. These are extreme low-flow periods when habitats are restricted and water quality is prone to deteriorate. They are a natural feature of ephemeral and episodic streams, but may harm perennial communities needing continuous access to water. Extended zero-flow periods can result in drying of the channel, leading to loss of connectivity between pools and even complete loss of aquatic habitat. Under natural conditions, some kinds of aquatic biota are able to recolonise dried channels, once flow resumes. PZ is calculated as:
PZ = 1 – 2 × [ max(PZr, PZc) – min( PZr, PZc) ] where
PZc = Proportion of zero monthly flows over the period of record under current conditions
PZr = Proportion of zero monthly flows over the period of record under Reference Condition 3. Low-Flow Metric (LF)
LF reflects changes in the magnitude of low flows under Reference and current conditions. Low- flow periods are a natural feature of many Australian rivers, but they reduce the availability of instream habitat and are stressful for some species of aquatic biota. LF is calculated as the mean of the lowest and second lowest monthly flows (bottom 12th and second bottom 12th flows, or 91.7th and 83.3rd percentiles), thus:
LF = (LF91.7 + LF83.3) /2 where LF91.7 is the range-standardized low-flow index based on the 91.7% exceedance flow, from
LF91.7 = 1–2 × | Pile(Q91.7r) – Pile(Q91.7c) | where
Q91.7c = Current 91.7% exceedance flow (ML) Q91.7r = Reference 91.7% exceedance flow (ML) Pile(Q91.7c) = Proportion of years that the annual 91.7th percentile current flow is exceeded by the annual 91.7th percentile Reference flow
Pile(Q91.7r) = Proportion of years that the 91.7th percentile Reference flow is exceeded by the annual 91.7th percentile Reference flow
The range-standardized low-flow index based on the 83.3% exceedance flow, LF83.3, is calculated in a similar manner. 4. Monthly Variation Metric (CV) CV compares flow variability between Reference and current conditions over all months of the year. Variations in flows and water levels affect the composition, structure and zonation of aquatic and riparian plant communities, and provide life-history cues for many plant and animal species. Reduced flow variation may indicate hydraulic changes, including reductions in longitudinal and lateral connectivity, hence habitat complexity. This index does not measure seasonal timing—a reversed seasonal regime could have the same score as a Reference regime. 23
CV compares the coefficients of variation (standard deviation divided by mean) of monthly flows under current and Reference Condition:
CV = CVr / CVc where
CVc = Current monthly coefficient of variation CVr = Reference monthly coefficient of variation 5. Seasonal Period Metric (SP) SP measures the shift between the months of maximum flow and minimum flow under Reference and current conditions. The seasonal timing of periods of low and high flow affects the responses of plant and animal communities. In the southern Murray-Darling Basin, the flora and fauna are adapted to high flows in winter/spring and low flows in summer/autumn, whereas the converse is true for northern regions of the Basin. Changes to seasonal patterns, such as those associated with irrigation, have caused significant changes in some riverine and floodplain communities. SP is derived from frequency distributions showing the percentage of years that maximum and minimum annual flows fall in a given month under current and Reference conditions. The minimum proportions (from current or Reference data) in each month are summed, as follows:
1 ⎧ ⎫ SP = ⎨∑∑[]min(), PHRPHC ii + []min()PLC , PLRii ⎬ 200 ⎩ ii⎭ where
PHCi = Percentage of years when the ith month has highest flow under current conditions
PHRi = Percentage of years when the ith month has highest flow under Reference Condition
PLCi = Percentage of years when the ith month has lowest flow under current conditions
PLRi = Percentage of years when the ith month has lowest flow under Reference Condition 6. Mean Annual Discharge Metric (MNAQ) MNAQ is the ratio of the long-term mean annual discharge under current conditions to that under Reference Condition. It should not be confused with the FSR Mean Annual Flow Index, which estimates changes in the proportions of time that mean annual flows are exceeded. It is difficult to link MNAQ to any specific ecosystem impact but, in general, virtually all aquatic, riparian and floodplain communities would be affected by significant changes in mean annual flow. 7. Median Annual Discharge Metric (MDAQ) MDAQ is the ratio of the long-term median annual discharge of current conditions to Reference Condition. A median indicates the discharge that prevails 50% of the time. Medians indicate the distribution of annual flows in terms of rank values rather than actual values, as does the mean. The median and mean coincide in a flow distribution that is symmetrical, but they diverge if the distribution becomes skewed toward high or low flows. 24
3.2.5 Aggregation and integration methods for hydrology The SRA design framework for the Hydrology Theme requires a spatially-unbiased sample of data from the drainage system. If these data are available, site-scale values can be spatially aggregated to Zone- (median value) and Valley-scale (average of Zone median values weighted by stream length). In fact, data could not be obtained to meet this design requirement and aggregation therefore, has not been attempted. This problem should be resolved in future but, for the present, metrics, indicators and the Sustainable Rivers Hydrology Index (SR-HI) are reported on a site-by-site basis. The SR–HI was generated by integration of five indicators, derived from the seven metrics in Table 3.2-1 (see further Section 3.2.4). The indicator for change in Low and Zero Flow Events (LZFE) integrates the Low-Flow (LF) and Proportion of Zero Flow (PZ) Metrics, and the indicator for Gross Volume (GV) integrates the change in Mean/Median Annual Discharge Metrics (MNAQ, MDAQ). In each case, integration was accomplished using the Indicator and Index Expert Rules (Appendix 1). The remaining indicators (High Flow Events, HFE; monthly flow Variability, V; Seasonality, S) are equivalent to their FSR counterparts (High Flows, HF; Monthly Variation, CV; Seasonal Period, SP). Indicator scores are scaled 0-100, where 100 is equivalent to Reference Condition. Their interpretation is described in Section 2.3. The Indicators were then integrated to yield SR–HI scores for each modelled stream section. According to the Index Expert Rules, changes in the frequencies of high- and low-flows and the duration of zero-flow events, represented by HFE and LZFE, are primary drivers of river health. Changes in flow variability and seasonality are secondary drivers, and are given less weight. Changes in gross annual volume (mean, median) are still less-influential, and are part-correlated with the other indicators (SKM 2005).
Table 3.2-1. SR Hydrology Index (SR–HI) and contributing indicators and metrics. Indicators are in order of decreasing influence on the Index Expert Rules (Appendix 1). Abbreviations in parentheses are from the Flow Stressed Ranking Procedure (Section 3.2.4)
Index Indicator Metrics
High-Flow Events, HFE High-Flow magnitude (HF) Low-Flow magnitude (LF) Low- and Zero-Flow Events, LZFE Proportion of Zero flow (PZ) SR–HI Variability, V Monthly flow Variation (CV) Seasonality, S Seasonal Period shift (SP) Mean Annual Discharge, MNAQ Gross Volume, GV Median Annual Discharge, MDAQ 25
3.3 Fish
3.3.1 Background More than 60 fish species are known from the Murray-Darling Basin, including a complex of species (Hypseleotris spp.) awaiting formal description. The total also includes 10 species that are alien, having originated outside Australia, and seven marine or estuarine species that enter fresh water. SRA methods for using fish as indicators rely on information about the identity, origin and condition of individuals, their abundance and the composition of communities. The methods were established for the Index of Biotic Integrity (IBI) in North America (e.g. Karr 1981) and the NSW Rivers Survey (Harris and Gehrke 1997). They were tested, refined and standardized during the SRA Pilot Audit (MDBC 2004a–e), and are documented in the SRA Protocols (MDBC 2007a).
3.3.2 Sampling methods In each Zone, seven fish sampling sites were chosen using a stratified-random procedure, with a minimal 18 sites per Valley. Each was the centre point of a one kilometre stream reach. This design was adopted following power analyses and benefit-cost analyses of species-accretion data from the SRA Pilot Audit, showing that further samples were unlikely to yield many more species. For Valleys with less than three Zones, more sites are added to each Zone in relation to its proportion of the total valley length. Montane Zones are often small, and are included only if the stream length in that Zone is longer than 120 km and more than 7% of the total Valley stream length. Sampling sites were selected from the stream network following MDBC (2004f). Field teams validated the location and resolved practical issues such as problems of access, lack of water or proximity to instream barriers or impoundments (channel sites only were suitable). The SRA Protocols specify methods for choosing alternative sites to deal with these issues. In the six-year SRA reporting cycle, each Valley will be sampled twice for fish. In the second round of samples (IP4-IP6), approximately one-quarter of sites will be ‘fixed sites’, re-sampled if they are available (some, for example, may become dry), and the remaining ‘roving sites’ will be reallocated. This procedure, determined by statistical modelling, is designed to adequately represent spatial and temporal variation within Valleys. Given limited resources for sampling, it permits trend detection and provides adequately for statistical comparisons between Valleys and Zones. Sampling generally was in low-flow conditions in spring-summer-autumn, but with flexibility to allow for high seasonal temperatures in northern areas and high irrigation flows in southern rivers. All main habitat types in the river channel at each site were sampled in proportion to their relative extents. For logistical reasons, floodplain wetlands and ephemeral streams were not sampled, although they are significant habitats for fish. Fish were sampled using boat-mounted, backpack or bank-mounted electrofishing gear, and bait traps (not ‘baited’, as often assumed). To standardize the sampling effort, the Protocol informs field teams on the appropriate mix and application of methods according to local habitat characteristics. All captured fish greater than 15 mm length were counted. Up to 50 fish of each species at each site, caught by each method, were identified, measured and examined. Larger catches were sub- 26 sampled. Variables recorded include species identity, abundance and the lengths and condition of individuals (e.g. presence of external parasites, lesions or other abnormalities), based on rapid visual appraisal. Fish were returned alive to the water after examination, except for voucher specimens needed for laboratory confirmation and alien pest species that, in some jurisdictions, must be humanely destroyed.
3.3.3 Reference Condition for Fish Reference Condition for Fish (RC-F) is the estimated Condition of fish communities that would have prevailed now, in a given Zone and Valley, in the absence of significant human intervention. It does not apply to particular sites, as habitat conditions vary and fish are likely to move between sites. As it is not possible to measure Reference Condition directly, it is determined by combining expert knowledge, previous research, museum collections and historical data, and is used in the calculation of several indicators. Scientists from each State participated in expert committees to review data on fish distributions throughout the Basin, and State-based research, leading to predictions of the distribution of each species in each Valley and Zone under Reference Condition. Estimates of Reference Condition are based on documented information that is amenable to revision and re-analysis in response to future improvements in knowledge. In addition, a semi-quantitative assessment of ‘Rarity’ is made for each species in each Valley and Zone. This predicts the likelihood of a species being found at a site, using SRA sampling methods, if the encompassing Zone is in Reference Condition. Estimates of Reference Condition in Zones and Valleys clearly have a strong influence on assess- ments of fish Condition, hence determinations of Ecosystem Health. In developing protocols for sampling and analysis, a considerable effort was made to consult many sources of information, avoid biases and represent Reference Condition communities as accurately as possible. Future assessments will depend less on the accuracy of these estimates, as they will be concerned more with temporal trends.
3.3.4 Variables, metrics and indicators From the primary data recorded for fish at each site, 12 metrics were derived and six were integrated as two indicators (Table 3.3-1). The indicators were integrated to provide the Sustainable Rivers Fish Index (SR–FI). The use of biomass data as a metric was enabled by estimating the weights of individual fish using empirical length-to-weight relationships for each species. Another metric, being investigated for possible future use, would be to measure recruitment (the accrual of potentially- reproductive individuals to populations). Other metrics investigated but not adopted include reproductive and migratory guilds, size structure and sensitivity/tolerance guilds. Fish Index (SR–FI) values for each Zone are integrated to yield the Index for the Valley. This is the mean of the median values for each Zone, weighted according to their relative stream lengths. The medians and means are accompanied by 95% confidence limits, which should be considered in comparing Index values (Section 2.3).
27
Table 3.3-1. Indicators and metrics used to calculate the Sustainable Rivers Fish Index (SR–FI). Abbreviations in parentheses
Indicator Metric Meaning
Compares number of native species predicted to Expectedness Observed to occur in the Zone under RC-F and the median number Expected ratio actually caught at sites. The number of predicted (SR–FIe) (OE) species is corrected downward for species likely to be rarely sampled under RC-F, using the SRA Protocol. Information on species richness relative to Observed to Compares native species predicted to occur in a Zone Reference Predicted ratio under RC-F (without correction for Rarity) and those Condition (OP) caught across all sites in that Zone.
Proportion native Nativeness Proportion of total biomass contributed by native biomass species. (SR–FIn) (prop_N_biom)
Information on Proportion native Proportion of individuals that are native species. proportions of abundance abundance, (prop_N_abund) biomass and species richness Proportion native Proportion of species that are native species. that are native species rather than alien (prop_N_sp)
3.3.5 Diagnostic metrics The Sustainable Rivers Diagnostic Indicator (SR-Fd) is not integrated with the Expert Rules for the SR-FI, but helps to identify symptoms of poor community Condition. Seven metrics comprising the SR-Fd (Table 3.3-2) are modified from those developed for the Index of Biotic Integrity (Karr and Chu 1997; Harris and Silveira 1999): • Two metrics (‘pelagic’, ‘benthic’) compare the numbers of species in key habitats with Reference Condition, with added expert opinion on the distributions of alien species. These are designed to reveal changes in communities associated with benthic (bottom) and pelagic (open-water) habitats. • Two other metrics (‘macro’, ‘mega’) compare the numbers of species in dietary groups (‘guilds’) with Reference Condition. These illustrate changes in the food web. ‘Mega- carnivores’ include such species as Golden perch, Freshwater catfish, Trout cod and River blackfish. ‘Macro-carnivores’ include Australian smelt, Climbing galaxias, Murray hardyhead, Yarra and Southern Pigmy perch and Flat-headed gudgeon. • The Total Abundance metric (‘T_abund’) compares the expected abundance of all (native and alien) fish against observed data, standardized by altitude (a surrogate for habitat size). It measures the habitat’s capacity to support numbers of fish. 28
• Fish with ‘Abnormalities’ (‘abnorm’) may indicate ill-health in populations. This metric rates the percentage occurrence of parasites, lesions and other injuries on individuals. It is recognized that parasites and injuries are strictly ‘abnormal’ only if they occur frequently. • Some species are ‘Intolerant’ (‘intol’) of contaminants (e.g. Australian smelt, trout species), salinity (young Silver perch, Murray cod), obstructed migration paths (Golden perch, Macquarie perch, Spangled perch), cold-water pollution (Bony herring, Silver perch) and other disturbances, and may be absent as a consequence. This metric compares an ‘intolerance’ rating for the community with that expected under Reference Condition (RC-F). Development of the Diagnostic Indicator is not finalized because some of the metrics have yet to be fully refined. In this report, values of SR–Fd are not reported, but noteworthy metric values are commented on.
Table 3.3-2. Diagnostic metrics in the Fish Theme. ‘All fish’ here includes native, introduced and alien species. Abbreviations for metrics in parentheses
Metric Description
Pelagic species richness Species richness (numbers) of all pelagic (mid-water) fish at (pelagic) each site compared to predicted richness.
Benthic species richness Species richness of all benthic (bottom-dwelling) fish at each (benthic) site compared to predicted richness.
Proportion macro-carnivores The proportion of all individual fish that are macro-carnivores (macro) (i.e. eat prey <15 mm length).
Proportion mega-carnivores The proportion of all fish that are mega-carnivores (i.e. eat (mega) prey >15 mm length).
Total abundance (T_abund) Median number of fish in a Zone, compared to the number predicted in a ‘good’ site at the same altitude range (determined from SRA data).
Fish with abnormalities Inverse median score of fish in a Zone with visible (abnorm) ‘abnormalities’ (diseases, tumours, wounds, parasites etc.).
Intolerant species richness Numbers of native and alien species intolerant of (intol) disturbances (e.g. poor water quality, sediment, cold-water pollution, migration barriers) compared to the numbers predicted.
3.3.6 Aggregation and integration methods for fish The method used to aggregate site-based scores to Zone- and Valley-scales was as follows: Zone scale
• The Zone score for each Metric (e.g. OE) is the median Metric score for sites in that Zone. The OP Metric score is an exception, being derived directly at the Zone scale. 29
• Metric scores were input to the Indicator Expert Rules to determine a Zone Indicator score (e.g. Expectedness, SR–FIe). • Zone Indicator scores were input to the Index Expert Rules to determine a Zone Theme Index score (e.g. SR–FI). Valley scale
• The Valley score for each Metric is the mean of median Metric scores for Zones, weighted by stream length. • Valley Metric scores were input to the Indicator Expert Rules to determine a Valley Indicator score. • Valley Indicator scores were input to the Index Expert Rules to determine a Valley Theme Index score. The Sustainable Rivers Fish Index (SR–FI) was generated from five Metrics grouped as two Indicators (Table 3.3-1). The first Indicator, ‘Expectedness’ (SR–FIe), concerns expected species richness and incorporates two metrics (OE, OP) that specify observed species richness in Zones and Valleys relative to Reference Condition. The second Indicator, ‘Nativeness’ (SR–FIn), integrates three metrics (prop_N_biom, prop_N_abund, prop_N_sp) (Table 3.3-1) containing information on the proportions of community biomass and abundance that are native rather than alien. The two Indicators were combined, using Index Expert Rules, to yield SR–FI scores for each Zone and Valley. Scores are scaled from 0-100, where 100 represents Reference Condition (in this case, RC-F). Their interpretation is described in Section 2.4. The Index Expert Rules, hence the SR–FI score, are based on the premise that changes in the numbers of expected species (quantified by the ‘Expectedness’ indicator, SR–FIe) will affect the overall condition of fish communities. A substantial loss of expected native species therefore indicates poor condition. The Index score may be further modified when ‘Nativeness’ (SR–FIn) is diminished by dominant numbers or biomasses of alien fish. Thus, a very low SR–FI score would indicate loss of expected native species and dominance by alien species; a high score would mean abundant expected native species and few alien species.
3.4 Macroinvertebrates
3.4.1 Background Benthic macroinvertebrates (bottom-dwelling invertebrates visible to the naked eye) are abundant, locally diverse, easily sampled and identified, and sensitive to natural and human-caused changes in rivers. More than 140 taxa (mainly taxonomic families) have been recorded in SRA sampling throughout the Basin. They include a diverse range of aquatic insects, crustaceans, molluscs, worms and other forms, in variable numbers. The composition of macroinvertebrate communities is strongly influenced by variations in flow regime, water quality and other conditions within and between sites, and there are regional variations due to biogeography, climate and other factors. The scales of sensitivity and response generally are smaller than those for fish. Most methods for using macroinvertebrates as indicators of river health rely on information about the identity and abundance of individuals and the composition of the community. In the SRA, sampling methods were those developed for the Australian River Assessment Scheme (AUSRIVAS), under the National River Health Program (Davies 2000), and adopted throughout Australia. The methods were trialled and refined during the SRA Pilot Audit (MDBC 2004a–f, 2007). 30
3.4.2 Sampling methods In each Valley, 35 macroinvertebrate sampling sites were chosen using a stratified-random procedure, ensuring at least three sites per Zone. Statistical power analyses in the SRA Pilot Audit confirmed that more sites were unlikely to improve assessments significantly. The numbers of sites per Zone were allocated according to the percentage of total valley stream length within each Zone in a Valley. Locations were then randomly selected from the stream network, following the SRA Sampling Protocol, without stratification by stream order or size. Field teams validated the locations and resolved practical issues, including problems of access and lack of water. The SRA Sampling Protocol (MDBC 2007a) specifies methods for choosing alternative sites. Each Valley is sampled twice for macroinvertebrates during the six-year SRA reporting cycle. In the second three-year cycle, approximately one-quarter of sites will be ‘fixed sites’, re-sampled each year if they are available (not dry), and the remaining ‘roving sites’ will be re-allocated annually. As for fish (Section 3.3.2), this balance provides for statistical trend detection and comparisons between Valleys and Zones, given the limited resources available for sampling. In selecting sites, the required minimum number of sites was spread across at least 25% of the stream network in a Zone. In future, sites will not be subject to this “minimum distance rule”. Sampling generally was in low-flow conditions, in spring or autumn, and conducted only in the stream channel. Riffle and edge habitats were sampled where possible. If riffle habitats were absent, as in most lowland reaches, edge habitats only were sampled. Floodplain wetlands and ephemeral pools and streams were not sampled, for logistical reasons, although they are significant habitats for macroinvertebrates. Macroinvertebrates were sampled using the AUSRIVAS kick-sampling method, where the collector disturbs the substratum over a 10m stretch of stream bed, and a range of micro-habitats, and captures macroinvertebrates in a standard net. Sample processing again follows standard AUSRIVAS protocols, with live- or laboratory-sorting and identification to generate a list of families observed at the site. Identification is at family level for most groups. For many, but not all, macroinvertebrates, families represent reasonably discrete functional ecological groupings (e.g. feeding modes, habitat associations etc.). In this report, for sake of readability, the term ‘families’ is used loosely, in preference to the technically correct ‘taxa’ (singular: ‘taxon’). Some groups referred to in this way are taxonomic groups other than families (e.g. Acarina, Chironominae, Hirudinea, Ostracoda). The AUSRIVAS sampling method does not accurately represent the abundances of macro- invertebrates, and numeric data from samples therefore are not used here in the assessment of Condition. Nor does the method adequately sample several groups of molluscs and crustaceans, especially larger species like freshwater mussels and crayfish. These limitations will be addressed in future refinements of the sampling protocol.
3.4.3 Reference Condition for Macroinvertebrates The Reference Condition for Macroinvertebrates (RC-M) is the estimated composition of benthic macroinvertebrate communities that would occur now, at a given site, Zone and Valley, in the absence of significant human intervention. Initially, the SRA had adopted the AUSRIVAS approach, based on data from best available sites (Whittington et al. 2001, MDBC 2004b), but this was problematic due to the highly-modified nature of streams in the Basin, and assessments showed little difference between Valleys. Reference Condition is now established by applying a ‘Filters’ approach, based on the traits (of species in families) that determine distributional limits for temperature, hydrology, geomorphology and biogeography. A Filters model was developed 31 for the SRA in 2006–07, and compared against AUSRIVAS outputs for several disturbance gradients (Walsh et al. 2007). The conceptual framework for the Filters method (Chessman and Royal 2004, Chessman et al. 2006) begins with a regional ‘pool’ of macroinvertebrate families. The distribution of each family is limited by the tolerances of its members to environmental conditions. Locally, high or low temperatures, for example, could exclude particular taxa. If the potential range of a family is estimated with regard for several environmental factors, and these factors are measured or estimated at a particular site, the pool of families that potentially could occur at that site can be identified. Filters were developed from a large database (over 330,000 records, plus environ- mental data) drawn mainly from the AUSRIVAS archive of the National River Health Program (Gray 2004). These were combined with remotely-sensed data for estimating Filter variables, evaluated against measured values. Using the Filters model, assessments of community condition at the site scale involve comparison of families present (‘observed’) at the site and those that potentially could occur (‘expected’). The comparison is based on the presence or absence of families, and not their relative abundances. No estimates have been made of the probabilities of occurrence of families at sites under Reference Condition, but these could be incorporated in future analyses. Following assessment of performance of the Filters-based metrics (Walsh et al. 2007), ISRAG had sufficient confidence in them to use them in SRA reporting. The Filters method is likely to ‘over-predict’ taxa at site scale, and may need further refinement. This has been addressed partly through use of the numerical bands described (Section 2.4).
Table 3.4-1. Diagnostic Metrics used to calculate the Sustainable Rivers Macroinvertebrate Index (SR–MI). SIGNAL is an acronym for Stream Invertebrate Average Grade Number (Section 3.4.4). Other abbreviations in parentheses
Index Metric Meaning
Observed to Expected Proportion of the number of families observed at a site ratio (Filters OE) predicted to occur under Reference Condition
SR–MI Observed to Expected SIGNAL score for the assemblage at a site compared SIGNAL ratio with that expected under Reference Condition (RC-M), (Filters SIGNAL OE) determined by the Filters method (see text)
3.4.4 Variables, metrics and indicators From the primary data recorded at each site, and outputs from the Filters model, two metrics are calculated (Table 3.4-1): • Filters OE Metric: The Filters OE metric is a ratio (Observed / Expected) equivalent to the proportion of families that are observed (‘O’) in field samples and those expected (‘E’) at sites under Reference Condition (determined by the Filters model). The metric attains a value of 100 when all expected families are observed, and falls to zero when no expected families are found. It indicates the effect of disturbance, if the disturbance causes the loss of expected families. In practice, it is rare for a disturbance to eliminate all macro- invertebrate families, and low values for sites in south-eastern Australia typically are 0–20. 32
Analysis of a large data set, including sites in and out of the Basin (Walsh et al. 2007), shows that, with the current formulation of the Filters model, maximal values for Filters OE are about 60. Values above 40 are considered high, and values below 20 are considered low. • Filters SIGNAL OE: SIGNAL (Stream Invertebrate Grade Number Average Level) is based on the sensitivity of macroinvertebrates to pollution or other disturbances. Each family is assigned a grade according to its tolerance, where 1 is high tolerance and 10 is high sensitivity. The ‘observed’ SIGNAL OE score is the sum of these grades divided by the number of expected taxa (determined by the Filters method), and the ratio between observed and expected scores is the Filters SIGNAL OE Metric. The Metric broadly indicates differences in the representation of disturbance-sensitive families relative to Reference Condition for Macroinvertebrates. It attains a value of 100 when the SIGNAL OE score of the observed sample equals that derived for the site under Reference Condition (from the Filters model), and declines as the observed SIGNAL OE score declines relative to that for Reference Condition. Low values for sites in south-eastern Australia typically are 50–80. Analysis of a large data set for sites in and out of the Basin (Walsh et al. 2007) shows that, with the current formulation of the Filters model, maximal values for Filters SIGNAL OE are about 125. Values above 100 are considered high, and values below 80 are considered low.
3.4.5 Aggregation and integration methods for macroinvertebrates The method used to aggregate scores to Zone- and Valley-scales was as follows: Zone scale
• The Zone score for each Metric (e.g. Filters OE) is the median Metric score for sites in that Zone. • Zone Metric scores were input to the Index Expert Rules to determine a Zone Theme Condition Index score. Unlike the Fish Theme, there was no intermediate step involving Indicators. Valley scale
• The Valley score for each Metric is the mean of median Metric scores for Zones, weighted by stream length. • Valley Metric scores were input to the Index Expert Rules to determine a Valley Theme Condition Index score. Unlike the Fish Theme, there was no intermediate step involving Indicators. Data integration was accomplished using Expert Rules, combining values of Filters OE and Filters SIGNAL OE to yield the Sustainable Rivers Macroinvertebrate Index (SR–MI) (Table 3.4-1). Values of SR–MI range from 0–100, where 100 is equivalent to Reference Condition for Macroinvertebrates. The Index Expert Rules, hence values of SR–MI, are based on the premise that changes in the numbers of expected families relative to Reference Condition (quantified by the Filters OE metric) indicate macroinvertebrate community Condition. The Filters SIGNAL OE Metric further modifies the SR–MI score when there are changes in the relative sensitivity to disturbance of families, relative to Reference Condition. A low SR–MI score would indicate the loss of many expected families, including disturbance-sensitive families. 33
3.5 Proposed Themes
3.5.1 Physical Form The proposed Physical Form Theme will assess the geomorphic condition of the channel- floodplain ecosystem at two spatial scales. Tier 1 is at the largest scale, and will characterise the entire drainage network as a census of physical river ‘types’, including descriptions of the richness, abundance, evenness, rarity and complementarity, compared to Reference Condition. Tier 2 is at a smaller scale, and will characterise the condition of a unit of stream drainage of a particular type in terms of the features of sampling sites in river ‘reaches’. In both Tiers, reach- and site-based data will be aggregated to Zone- and Valley-scales for reporting. Tier 2 assessments will be based on metrics and indicators relating to channel form, bank dynamics, bed dynamics and floodplain features, and will indicate changes in geomorphic form and process. Sites will be selected randomly, stratified by river types and Zones. Field observations will be supported by SEDNET (an expanded, refined version of SedNet, a program used to model sediment dynamics for the National Land and Water Resources Audit, 2001) and GRADFLOW (a spatial flow-inundation model developed by CSIRO). Reference Condition for the proposed metrics will be defined from data from Reference sites, historical maps and air- photographs and model outputs.
3.5.2 Vegetation The proposed Vegetation Theme will assess channel-floodplain vegetation at two spatial scales. Tier 1, the largest scale, will track catchment-scale changes in the extent and type of riverine vegetation relative to Reference Condition. A Basin-wide inventory of the extent and distribution of vegetation types will be repeated every six years, mainly using satellite imagery. Tier 2 will characterise the vegetation at reach scale, based on data from sampling sites, using individual plots and transects in channel, riparian and floodplain environments. Indicators will be related to taxonomic composition and disturbance, nativeness/weediness, function (e.g. regeneration, crown coverage) and structure. Data will be collected by field measurements and by aerial imagery. In both Tiers, reach- and site-based data will be aggregated to Zone- and Valley-scales for reporting.
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4. Operations
4.1 Introduction This report marks the completion of Implementation Periods 1–3 (2004–07). ISRAG considers that the sampling, analyses, program management and quality assurance protocols in the Fish and Macroinvertebrate Themes have been consistent with the scientific design and conceptual basis of the SRA. The program is meeting the need for auditing the ecological health of the Basin’s rivers, and is providing independent, scientifically-credible assessments. Implementation of these two Themes has proceeded as planned, despite some issues associated with the scarcity of sites due to drought and, occasionally, practical problems with sampling. During the reporting period, fish samples were taken at 487 sites, and macroinvertebrate samples were taken at 773 sites. The Hydrology Theme has experienced several problems (Section 4.4), including delays and data limitations, analysis and reporting inconsistencies among States and incomplete quality assurance procedures. Assessments in this report therefore are limited to determination of site-scale metrics, allowing only qualitative interpretations of hydrological condition at the Valley scale. A process is underway to resolve these issues for the next SRA round. This Section reviews the status of the three Themes. It refers to the first cycle of the Macro- invertebrate Theme (one series of samples from all Valleys), completed in IP2, and the first cycle of the Fish Theme, completed in IP3. Although further macroinvertebrate samples were taken during IP3, these are part of the second cycle and are not considered here. This Section describes:
• The numbers and locations of sampled sites compared to Sample Plan requirements; • Data for the Hydrology Theme; • Data management for the Fish and Macroinvertebrate Themes; and • Program management, including reviews of field sampling procedures.
4.2 Sample Plans The SRA Team provided Field Site Sample Plans to sampling teams in each State, identifying prescribed ‘SRA sites’ on the stream network. In the field, teams located these sites using GPS or topographic maps and recorded locations where sampling occurred, following a Site Validation Protocol. Designated SRA sites were presumed to be the centre of a 1000 m reach, but it was possible that the site would not fall precisely on the river, requiring teams to relocate prior to sampling. These differences could introduce a spatial bias if sampling teams made systematic choices (for example, to consistently move nearer to road crossings). A spatial analysis is planned to compare the statistical distributions of SRA site attributes like altitude and distances to nearest road and nearest bridge to the same attributes for all reaches in the stream networks. About 74% of fish and 83% of macroinvertebrate field sampling sites fell within 500 m of prescribed SRA sites, effectively within the nominated 1000 m reaches. About 84% of fish and 92% of macroinvertebrate sites were within 1000 m of SRA sites. The proximity of field sampling sites to SRA sites improved over time, as site-validation protocols were improved. 35
4.3 Sampling compliance
4.3.1 Overview Drought created significant difficulties for site allocation, validation and sampling, particularly in the northern Valleys. In some southern Valleys, bushfires also hindered sampling. Appendix 2 compares the numbers of sites sampled in each Valley Zone and the numbers of sites specified in the sampling plans for the respective Themes. It also shows for Valley-Theme combinations the differences between the number of sites sampled and the number of sites required. The differences refer to sites missed because of dry conditions, problems of vehicle access or other reasons. Where additional sites were sampled, they have been included in analyses if they conformed to the respective sampling plan. Differences in the methods used to define the stream networks for the Fish and Macroinvertebrate Themes (Section 2.2.4) led to unequal numbers of Zones in one Valley, the Loddon (2 Fish, 3 Macroinvertebrate Zones). No sampling was undertaken in South Australia during IP3 (fish were sampled in IP1; macro- invertebrates were sampled in IP2). Practical issues in IP1 delayed fish sampling until early winter at some sites in the Lower Murray Valley, potentially causing a bias in SRA assessments because Carp tend to be under-represented in winter catches.
4.3.2 Implications for the Fish Theme ISRAG considers that the disparities between numbers of required and sampled sites did not have serious consequences for analyses of fish data. The more noteworthy departures were as follows:
• Castlereagh: At the Valley scale, 86% of the required number of sites was sampled, but in the Lowland Zone only 57% of the required number was sampled, owing to drought. • Lachlan: Sampling of an extra Upland Zone site meant that the site-number requirements were met for the Valley, but only 86% of required sites was sampled in the Slopes Zone. • Ovens: For the Valley, 93% of the required number of sites was sampled, but only 71% of Montane Zone sites. • Warrego: Eighty percent of the required number of sites was sampled in the Valley, and eight rather than the required 10 sites were sampled in the Lowland Zone. • Wimmera: For the Valley, 94% of the required number of sites was sampled. Eight Lowland Zone sites were sampled (89% of the required number).
4.3.3 Implications for the Macroinvertebrate Theme ISRAG considers that disparities between numbers of required and sampled sites did not have serious consequences for analyses of macroinvertebrate data, other than possibly for the Castlereagh Valley. Departures were as follows:
• Border Rivers, Goulburn, Loddon, Upper Murray, Wimmera: In these Valleys, 97% of the required numbers of sites was sampled. • Castlereagh: For the Valley, 51% of required sites was sampled, with 46%, 38% and 78% of required sites sampled in the Lowland, Slopes and Upland Zones, respectively. The data were accepted for analysis, but as there were shortfalls in all three Zones, and the percentage of sites sampled at the Valley scale was low, an evaluation should be made later, using the Filters model (Section 3.4.3). 36
• Kiewa: Eleven of the required 12 sites were sampled in the Upland Zone. One more site than required was sampled in the Slopes Zone, so that the Valley requirement was met. • Mitta Mitta: Assessments were based on 32 sites (92% of the required number). One more site than required was sampled in the Slopes Zone. • Lower Murray: Assessments were based on 33 (94%) of the required 35 sites. • Namoi: Twenty five (71%) of 35 required sites were sampled, with the largest discrepancy in the Slopes Zone (44% of required sites). Further evaluation is recommended, using the Filters method (Section 3.4.3).
4.4 Hydrology Theme Extensive delays in determining the location of representative sites and the delivery of modelled data by some States caused substantial problems, and there were inconsistencies between models, estimations of Reference Condition and the durations of site records. The hydrological assess- ments in this report therefore do not meet rigorous SRA design principles. A process involving ISRAG, the States and the SRA Team is underway to resolve these issues for the next report. Data were supplied from Queensland (67 sites), MDBC (59 sites), New South Wales (176 sites) and Victoria (211 sites). Following removal of duplicate data supplied by Queensland and New South Wales for the shared Border Rivers valley, and removal of inappropriate sites and incorrect data, 469 sites remained for analysis. Metrics were derived using software developed by Sinclair Knight Merz (SKM 2004, 2005) for the Flow Stressed Ranking (FSR) project (Section 3.2.4). Following trials, the software was refined to meet SRA automation and data-management needs, and extended to output annual discharge statistics. Outputs were compared to independently-measured annual discharge statistics and other data, and to reported values for sites in Victoria where FSR and SRA input data were identical. No discrepancies were detected. Delays in delivery meant that hydrology data did not pass through the data-acceptance procedures applied to fish and macroinvertebrate field data returns (Section 4.5.1). Nevertheless, the data were from well-established models, and subject to the quality-assurance methods applied to those models.
4.5 Data management
4.5.1 Data returns Field data gathered by State agencies were received by the SRA Team and validated via the SRA Data Acceptance Protocol, which included a series of assessments of compliance. A more- structured system to classify and document data issues was implemented after IP1. ‘Errors’ were detected where one or more data elements did not comply with the protocol, and ‘Warnings’ indicated the need to confirm aspects of the supplied data. Following implementation of this system, a total 28 ‘Errors’ and 25 ‘Warnings’ have occurred, and entire datasets have been replaced on two occasions.
4.5.2 Data quality Checks were applied at each stage of data processing, from acceptance to derivation of indicators and construction of spreadsheets, charts and other reporting materials. Following acceptance, data integrity was maintained using one-to-one comparisons of supplied data to as-held data, including ‘random walks’ and comparative analyses of calculations conducted by two different systems, the 37 use of test datasets, step-wise code testing and creation of particular ‘modules’ for data management across related files and functions.
4.5.3 Contextual analysis A contextual analysis has commenced, aimed at identifying outliers, anomalies and regional- ization effects in the Basin-wide data set. The results will be used to establish the domain of acceptable values for each attribute and to further improve the data-acceptance process in future.
4.6 Program management
4.6.1 Quality Assurance The SRA Quality Assurance Project Plan documents the activities and procedures that contribute to the quality of program data, under the guidance of the Quality Assurance Taskforce. The Plan covers document control, protocol management and data verification and validation, and is complemented by documents which detail Quality Assurance and Quality Control activities from site selection to the derivation of metrics, indicators and indexes, and report writing. In addition to documenting current practices, the Plan provides a mechanism for improvements to the program. Quality Assurance protocols were used as quality control tests at each of the stages in data transformation, from acceptance of data to charting of metrics.
4.6.2 Review of field sampling and analysis Reviews have been carried out by the Murray-Darling Freshwater Research Centre of procedures used in IP2–IP3 by sampling teams for the Fish and Macroinvertebrate Themes. The reviews were intended to evaluate quality assurance and quality control activities among field teams and to provide recommendations to be considered for IP4, through the Quality Assurance Taskforce, in consultation with other SRA taskforces. Field teams in SA were not sampling at the time of review and are yet to be assessed. A summary of observations and outcomes for each review follows. Fish Theme Observations
• Variations between States in identifying and recording taxa and abnormalities. • Variations (minimal) in bait-trap placement. • Variations in handling pest species (SRA sampling is non-destructive except for voucher specimen collection and disposal of noxious or alien species, subject to State policies). • Variations in use of anode net, subject to State Occupational Health and Safety policies. Implications for SRA Report 1 data
• Variations between States in applications of the Protocol relating to electrofishing gear and sampling methods have yet to be assessed formally, causing minor uncertainty over relative sampling power. • The potential for errors in taxonomic identification remains. To be resolved by additional staff-training workshops, field identification keys and voucher collections. • ISRAG considers that while these issues require management, they do not greatly affect the conclusions in this report. 38
Outcomes The following recommendations are being reviewed and/or implemented for IP4:
• Sampling should continue to be undertaken by SRA-trained staff. • States should conduct SRA training before each sampling season. • Laminated Basin fish guides are needed for field use. • Teams should photograph live specimens of taxa difficult to identify in the field. • Guidelines are needed for bait-trap placement. • Standardised methods are needed for checking and recording abnormalities. • Standard guidelines are needed for handling pest species. • Variations in use of electrofishing gear require further assessment.
Macroinvertebrate Theme Observations
• Sampling teams follow State-specific AUSRIVAS protocols rather than consistent, Basin- wide protocols. • Variations in the type and proportion of habitats sampled. • Variations in the number of sweeps taken and the areas covered by sweeps. • Minor variations in live-pick methods (due to State-specific AUSRIVAS protocols). • Variations in sorting tray sizes, net sizes and net shapes. • Variations in identification keys used, in taxa included in State-specific AUSRIVAS models, and the levels to which taxa are identified. • Recent taxonomic revisions (e.g. Odonata) are not consistently represented in State agencies’ identification keys. • Variations in quality-control checking of identifications and enumerations. • Differences between State protocols (e.g. inclusion of rocks in sweep-net sampling in South Australia; exclusion of macrophytes in Queensland). Implications for SRA Report 1 data
• Variations in sampling protocols, driven by State protocols, caused problems in defining Reference Condition. These continued to be issues during IP1–IP2. • Discrepancies between States in the taxonomic groups retained by sampling were resolved by exclusion of certain taxa (e.g. Cladocera, Copepoda) from analyses. • Discrepancies in retention maxima for taxa in live-pick samples were managed by using presence/absence data only in calculating SIGNAL OE scores. • Problems with differences and errors in taxonomic identification remain for resolution. • ISRAG considers that while these issues require management, that they do not greatly affect the conclusions in this report. Outcomes
• A Filters model (Section 3.4.3) to predict the distribution of invertebrate families under Reference Condition was implemented for the first time in SRA Report 1 (in previous reports, Reference Condition was based on State-specific AUSRIVAS models). Modelled 39
data were imported into the SRA database and analyses including derivations of metrics and indicators were implemented by the SRA Data Manager. • To cater for the new model, the SRA Team rebuilt the software code running the analysis to confirm operations on raw data and generation of confidence limits. A sample dataset containing test records was used to confirm that the Expert Rules processor operated properly. The normalization algorithm applied prior to applying Expert Rules also was confirmed to be working as required. Output tables were checked visually, as a final step. • Development and adoption of the Filters model included a review of taxa to be included for modelling. Some taxa were removed to reduce variation associated with inconsistent identification and inadequate sampling technique. Standardisation of the sampling protocol to address these concerns will be considered for adoption in IP5. • A test of inter-operator variability will be considered, following implementation of a standard protocol. • SRA standard identification keys for macroinvertebrate groups will be available to State agencies and sampling teams.
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5. Assessment of Valleys
5.1 Basin context
5.1.1 Ecosystem Health and Condition For easy reference, this section provides compact summaries of Ecosystem Health and Condition assessments. Comparisons and discussion are deferred, however, to Section 6. Ecosystem Health assessments are shown in Figure 5.1-1. Condition assessments for the Hydrology Theme are shown in Table 5.1-1, and assessments for the Fish and Macroinvertebrate Themes are shown in Figures 5.1-2–3 and Tables 5.1-2–3, respectively.
5.1.2 Rainfall and drought Annual rainfall deficits for the Basin in 2004–07 are shown in Figures 5.1-4–7, respectively. These maps broadly indicate the environmental conditions that prevailed in each of the Valleys during the Audit period. At the wider Basin scale, they show that the dry conditions of the last decade were intensified during the Audit period, leading to the severe drought that still prevails over parts of the Basin (e.g. MDBC 2007b). These maps were designed to support more detailed hydrological analyses than have been possible in this report, but are provided for reference. In 2002, the Basin experienced a 1 in 20 year low annual flow. Similar flows occurred in 1982-83 (MDBC 2003a), but three of the six driest years on record have occurred since 2002 (D. Dreverman, MDBC, pers. comm.). Commenting on conditions in 2007, in the third year of the present SRA cycle, the Murray-Darling Basin Commission (MDBC 2008) reported that: “… the calendar year of 2007 was extremely dry in its own right. Total system inflow, including Menindee (the aggregate of inputs from the northern Basin) was about 2100 GL – the third lowest inflow year out of 116 years of records. Coming immediately after the lowest inflow year on record is unprecedented in the historic record. The two year total inflow ending December 2007 was about 3350 GL – about half of the previous two year minimum of 6500 GL (1937–1938) and only 15% of the long term average for a two year period”. Although the northern Basin catchments received near-average to above-average rainfall (Figures 5.1-5–9), they contributed comparatively little to the total Basin discharge. Modelled mean annual ‘natural’ discharge in the Darling is about 1,900 GL, and that for the Murray tributaries (Upper Murray, Murrumbidgee, Mitta Mitta, Kiewa, Ovens, Goulburn) is 12,400 GL. Indeed, the dry conditions have been most persistent and severe in the Murray catchments, as the rainfall-deficit maps show. Thus, in the latter part of the SRA reporting period, most of the rivers (by length) in the Basin have experienced conditions equivalent to the long-term average, but discharge from the Basin as a whole has been at an extreme low. Drought before and during sampling will have influenced data from the Fish and Macro- invertebrate Themes, but complex interactions and time-lagged effects make it difficult to predict the nature of these effects. There will be long-term effects through changed habitat conditions. Metrics supporting the Hydrology Theme are based on long-term modelled data, and involve comparisons of ‘natural’ and ‘current’ flows. They are not likely, therefore, to indicate immediate conditions. More immediate assessments may be included in future development of the Hydrology Theme. 41
WARREGO
CONDAMINE
BORDER RIVERS PAROO
GWYDIR
NAMOI CASTLEREAGH
MACQUARIE
DARLING
LACHLAN
LOWER MURRAY MURRUMBIDGEE
AVOCA CENTRAL MURRAY
WIMMERA UPPER MURRAY BROKEN LODDON OVENS MITTA MITTA CAMPASPE GOULBURN KIEWA
0 100 200 300 400 500 km 1:7,500,000
Figure 5.1-1. Compact summary: Ecosystem Health for all Valleys
42
SR Hydrology Index Number Valley of Sites Minimum Median Maximum
Avoca 11 75 96 100 Border Rivers 34 70 100 100 Broken 19 41 97 100 Campaspe 18 58 79 100 Castlereagh 3 100 100 100 Condamine 22 44 78 100 Darling 7 47 67 74 Goulburn 40 34 95 100 Gwydir 19 37 64 99 Kiewa 14 90 100 100 Lachlan 21 66 100 100 Loddon 30 34 82 100 Macquarie 41 55 100 100 Mitta Mitta 18 78 100 100 Murray, Lower 14 16 57 64 Murray, Central 32 36 66 100 Murray, Upper 12 47 100 100 Murrumbidgee 26 36 100 100 Namoi 22 59 100 100 Ovens 23 81 98 100 Paroo 4 100 100 100 Warrego 5 93 100 100 Wimmera 34 13 88 100
Table 5.1-1. Compact summary: Sustainable Rivers Hydrology Index (SR–HI) for all Valleys. These data are for selected locations and are not representative of the Valleys in a statistical sense (see Section 3.2.5). Median values are shown, with minima and maxima 43
100
Good 80 Moderate 60 Poor
40 Very Poor Fish Index, SR-FI Sustainable Rivers 20 Extremely Poor
0 Paroo Kiewa Avoca Namoi Ovens Gwydir Darling Broken Loddon Lachlan Warrego Wimmera Goulburn Mitta Mitta Mitta Macquarie Campaspe Condamine Castlereagh Border Rivers Border Murray, Upper Murray, Lower Murray, Murrumbidgee Murray, Central Murray,
Valley Lower Median Upper
Avoca 30 46 61 Border Rivers 55 60 69 Broken 25 35 50 Campaspe 2 5 17 Castlereagh 0 14 23 Condamine 47 63 71 Darling 56 59 68 Goulburn 2 5 17 Gwydir 43 51 56 Kiewa 19 26 44 Lachlan 5 14 28 Loddon 3 12 27 Macquarie 20 34 40 Mitta Mitta 3 10 39 Murray, Lower 49 53 58 Murray, Central 40 54 64 Murray, Upper 14 14 26 Murrumbidgee 5 14 21 Namoi 48 59 63 Ovens 33 50 57 Paroo 76 78 91 Warrego 17 56 58 Wimmera 36 47 57
Figure 5.1-2 (above), Table 5.1-2 (below). Compact summary: Sustainable Rivers Fish Index (SR–FI) for all Valleys. Median values are shown, with 95% confidence limits. The chart includes the SRA colour standard and key 44
100 Good 80 Moderate 60 Poor 40 Very Poor Sustainable Rivers Rivers Sustainable 20 Extremely Poor Macroinvertebrate Index,SR-MI Macroinvertebrate 0 Paroo Kiewa Avoca Namoi Ovens Darling Gwydir Broken Loddon Lachlan Warrego Wimmera Goulburn Macquarie Mitta Mitta Campaspe Condamine Castlereagh Border Rivers Murray, Upper Murrumbidgee Murray, Lower Murray, Central Murray,
Valley Lower Median Upper
Avoca 29 34 37 Border Rivers 58 66 75 Broken 46 51 53 Campaspe 36 41 45 Castlereagh 36 41 52 Condamine 51 55 64 Darling 48 52 56 Goulburn 49 50 59 Gwydir 51 56 61 Kiewa 58 59 70 Lachlan 49 53 56 Loddon 45 51 54 Macquarie 46 50 54 Mitta Mitta 51 59 65 Murray, Lower 47 48 56 Murray, Central 41 46 50 Murray, Upper 59 65 69 Murrumbidgee 43 48 52 Namoi 48 52 57 Ovens 51 57 59 Paroo 58 64 72 Warrego 39 49 53 Wimmera 29 36 44
Figure 5.1-3 (above), Table 5.1-3 (below). Compact summary: Sustainable Rivers Macroinvertebrate Index (SR–MI) for all Valleys. Median values are shown, with 95% confidence limits. The chart includes the SRA colour standard and key 45
Figure 5.1-4. Rainfall deficits in the Murray-Darling Basin, 2004. Data source: Bureau of Meteorology
Figure 5.1-5. Rainfall deficits in the Murray-Darling Basin, 2005. Data source: Bureau of Meteorology 46
Figure 5.1-6. Rainfall deficits in the Murray-Darling Basin, 2006. Data source: Bureau of Meteorology
Figure 5.1-7. Rainfall deficits in the Murray-Darling Basin, 2007. Data source: Bureau of Meteorology 47
5.2 Avoca Valley
5.2.1 Hydrology
Figure AVO.1: Avoca Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for selected sites on the Avoca mainstem were 75–99, indicating Moderate to Good Condition (Lowland Zone: Moderate to Good; Slopes Zone: Good).
The Avoca Valley covers 12,000 km2, or about 1% of the Basin area. The river flows from the Great Dividing Range northward to the Murray, terminating in the Avoca Marshes and Lake Bael Bael, at the edge of the Kerang Wetlands. Floodwaters are dissipated across a wide area, the Avoca Floodway. There are no instream storages apart from 12 low-level weirs that extend local water-supply during low-flow periods (Vlok et al. 2007). There is some irrigation of vines in the southern region (upstream of Charlton) and pasture in the north. Irrigation in the upper reaches is often supported by runoff-harvesting stored in farm dams rather than by direct diversions. 48
Figure AVO.1 shows values of the Hydrology Index for five selected sites and Table AVO.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams in the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Sites 1–3, on the Avoca mainstem (Lowland Zone), were Near Reference Condition or showed a Moderate Difference from Reference Condition (SR–HI = 75–92). Two tributary sites in the Slopes Zone (Sites 4, 5) were Near Reference Condition (SR–HI = 94, 99). The indicators show:
• High-Flow Events: Near Reference Condition, with a 4–16% reduction at all sites. • Low- and Zero-Flow Events: Moderate Difference from Reference Condition in the Slopes Zone but a Very Large Difference in the Lowland Zone. Most tributaries were Near Reference Condition. • Variability: Near Reference Condition at all sites. Reduced at the most downstream site, slightly modified at others. • Seasonality: Near Reference Condition at most sites, but a Moderate Difference from Reference Condition was apparent downstream site (e.g. Site 1). • Gross Volume: Mean and median annual flow volumes were reduced in mainstem sites by 15–30% and 30–50%, respectively, relative to Reference Condition. At all five selected sites, indicators for Gross Volume of annual flow (GV) show differences from Reference Condition, indicating diversions. Site 4 on Mountain Creek, a small tributary, showed a Large Difference, with GV = 50, but other indicator values at that site showed little difference. This may be an effect of intercepting runoff in farm dams, changing the volume of stream discharge without modifying other attributes of the hydrograph. At mainstem sites, the Low- and Zero-Flow Events indicator (LZFE) is the most reduced. This reflects substantial diversions during summer and consequent increases in the frequency and duration of low- and zero-flows. The impacts may be exacerbated by catchment erosion and stream sedimentation (Vlok et al. 2007); filling deep pools that could offer refuges for native fish. In general, the flow regime of the Avoca Valley had reduced magnitudes of annual flow volumes and high- and low-flow events, but little change in variability or seasonality.
Table AVO.1: Avoca Valley: SR Hydrology Index and indicators. Sites are shown in Figure AVO.1. US: upstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Avoca US Bael Bael Lowland 75 91 34 85 77 72 2 Avoca at Coonooer Bridge Lowland 92 95 68 93 95 79 3 Avoca at Archdale Junction Lowland 89 89 60 92 93 81 4 Mountain Creek Slopes 94 84 100 92 94 50 5 Glenlogie Creek Slopes 99 96 84 95 95 88
49
5.2.2 Fish
100 90 Good 80 Moderate 60 46 Poor 40 Very Poor 20 24 Extremely Poor 0 Valley lowland slopes
Figure AVO.2: Avoca Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median. 50
The Avoca Valley fish community was in Poor Condition. The Lowland Zone in partic- ular had few fish and lacked almost two thirds of the predicted native species. The Valley had lost much of its native species richness and alien species contributed over 90% of the biomass in samples.
Eighteen sites were surveyed across two Zones of the Avoca Valley in November 2005, yielding 905 fish. Analyses showed a Large (±) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 46 (CL 30–61). • Only 35% of expected native species were recorded. • Nativeness showed a Very Large (±) Difference from Reference Condition. • Numbers in the Lowland Zone were very low (average 27 fish per site). Figure AVO.2 shows sampling sites, Zones and corresponding SR–FI values, and Table AVO.2 shows Index values, Indicators, Metrics and derived variables. Only five of 16 predicted (RC–F) native fish were recorded in the Lowland Zone, with four alien species. In the Slopes Zone, all six RC–F species were recorded, with three alien species. SR–FI for the Avoca Valley was above the average for all Valleys (Section 6.3.4), and close to that for the Wimmera, Ovens and Gwydir. The Lowland Zone community was in much poorer condition (SR–FI = 24) than that in the Slopes Zone (SR–FI = 90). The wide confidence interval for SR–FI in the Slopes Zone was due mainly to variability in Nativeness. The Valley community showed a Large (±) Difference from Reference Condition (Lowland Zone: Very Large (±) Difference, Slopes Zone: Near Reference Condition (–)). The Valley score was interpreted conservatively, given the low SR–FI score, low total abundance and low diversity of species in the Lowland Zone, and the predominance of alien biomass in both Zones. Nativeness and Expectedness varied in both Zones. Moderate numbers of fish were caught in the Slopes Zone (average 79), but there were few in the Lowland Zone (27), and a Valley average of only 11.5 native fish per site. In the Lowland and Slopes Zones, native species were 42% and 80% of individual fish, respectively. Two alien species, Eastern gambusia and Carp, were numerically dominant at most Lowland Zone sites, and Redfin perch also were common. The Lowland Zone had low native species diversity, and only 35% of 16 RC–F species were caught. In the Slopes Zone, all six RC-F species were caught and there were locally high abundances of Australian smelt, Obscure galaxias and River blackfish. Large alien species, especially Carp and Redfin perch, dominated the biomass in the two Zones. The native fish mainly were small species, plus a few larger Golden perch at three sites. Alien fish, on average, were 50 times larger than native fish. These factors contributed to an extremely low percentage of native biomass, averaging only 8% across the Valley and demonstrating the dominance of alien species. Table AVO.3 shows native species abundances in the Avoca Valley compared with Reference Condition. Southern pygmy perch were predicted to be common in the Lowland Zone, but were not caught at any sites. Other species not caught, but predicted to be rare or moderately rare in one or more Zones under Reference Condition, included Silver perch and Freshwater catfish. 51
Few fish in the Slopes Zone (1.6%) had visible Abnormalities, but there were more in the Low- land Zone (7.5%). Mega-carnivores such as Golden perch and Murray cod were rare or absent from catches.
Table AVO.2: Avoca Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes
Fish Index 46 (30–61) 24 (14–50) 90 (51–97 Expectedness Indicator 50 (39–67) 33 (28–52) 82 (61–100) Nativeness Indicator 36 (17–55) 23 (14–57) 70 (8–90) Metrics Total species 10 9 9 Native (RC–F) species 6 5 6 Predicted RC–F species count 16 16 6 Alien species 4 4 3 Caught/Predicted native species (%) 35 31 86 Numbers of fish Mean fish per site 50 27 79 Native individuals (%) 68 42 80 Fish biomass Biomass/site all species (g) 7,006 5,029 9,478 Mean native biomass/fish (g) 16 39 11 Mean alien biomass/fish (g) 404 288 547 Biomass native (%) 8 9 7
52
Table AVO.3: Avoca Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes
Australian smelt 34 55 89 Bony herring 0 0 Carp gudgeons 0 0 Dwarf flat-headed gudgeon 0 0 Flat-headed galaxias 0 0 Flat-headed gudgeon 71 6 77 Freshwater catfish 0 0 Obscure galaxias 4 420 424 Golden perch 4 2 6 Murray cod 0 0 Murray hardyhead 0 0 Murray–Darling rainbowfish 0 0 River blackfish 2 17 19 Silver perch 0 0 Southern pygmy perch 0 2 2 Un-specked hardyhead 0 0
Alien species
Carp 57 43 100 Eastern gambusia 87 70 157 Goldfish 1 1 Redfin perch 14 16 30 53
5.2.3 Macroinvertebrates
100 Good 80 Moderate 60 Poor 40 34 34 30 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure AVO.3: Avoca Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 54
The Avoca Valley macroinvertebrate community is in Very Poor Condition (poorest in the Basin). Most sites had few ‘expected’ families, including disturbance-sensitive families.
Thirty five sites were surveyed across two Zones of the Avoca Valley in April 2005, yielding 6,707 macroinvertebrates in 54 families (39% of Basin families). Analyses showed a Very Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 34 (CL 29–37). • Low proportion of expected families (Filters OE = 21). • Low SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 79). The SR–MI score for the Avoca Valley was the lowest of all Valleys. Both Lowland Zone and Slopes Zone communities showed a Very Large Difference from Reference Condition (SR–MI = 34, 30, respectively). A wide confidence interval (14 points) for the Slopes Zone indicates more variability there, but all sites nevertheless showed a Large to Very Large Difference from Reference Condition. Figure AVO.3 shows sampling sites, Zones and SR–MI values, and Table AVO.4 shows metrics and derived variables. A little over half (57%) of the expected families were found in the Valley. Family richness generally was low compared to Reference Condition. Diversity was low (average 17 families per site), with the Slopes Zone being most diverse (average 21 families per site). Most (75–84%) of the Valley fauna was found in each of the Zones. Expectedness (Filters OE) and Filters SIGNAL OE scores were low and varied little among sites, with slightly more variation in the Slopes Zone. Table AVO.5 shows that most sites in both Zones had moderate to low Filters OE and Filters SIGNAL OE scores, and most Slopes Zone sites also had low Filters SIGNAL OE scores. Thus, most sites had a substantially lower than expected diversity of macroinvertebrates, and a similar loss of disturbance-sensitive families. Table AVO.6 shows ‘common’ and ‘rare’ families. The four common families were marsh beetles, whirligig beetles and water scorpions (Scirtidae, Gyrinidae, Nepidae). There were 17 rare families (at few sites, compared to other Valleys), including crustaceans, snails and insects.
55
Table AVO.4: Avoca Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Index SR–MI 34 34 30 (29–37) (31–39) (20–34) Metrics Filters OE 21 21 24 (20–23) (20–23) (19–24) Filters SIGNAL OE 79 82 72 (75–80) (79–85) (68–76) Families Families per site 17 15 21 minimum – maximum 7–28 7–20 10–28 Total families 54 41 45
Table AVO.5: Avoca Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Valley Zone Lowland Slopes
Number of sites 35 22 13
Filters OE High Medium 25 16 9 Low 10 6 4
Filters SIGNAL OE High Medium 15 13 2 Low 20 9 11
56
Table AVO.6: Avoca Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin; ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 22 13 35 Number of families sampled 42 47 56 Percent of families in Basin 38.5 38.5 39.2 Percent of families in Valley 75 84 100 Percent of sites by Zone Lowland Slopes VALLEY
Common Scirtidae 55 62 57 Gyrinidae 36 54 43 Nepidae 32 23 29 Muscidae 14 9 Rare Caenidae 23 15 20 Gomphidae 9 6 Corbiculidae 8 3 Elmidae 8 3 Hirudinea 8 3 Hydrobiidae 8 3 Janiridae 8 3 Libellulidae 5 3 Lymnaeidae 5 3 Mesoveliidae 8 3 Notonemouridae 8 3 Philorheithridae 5 3 Polycentropodidae 5 3 Protoneuridae 5 3 Sphaeriidae 8 3 Temnocephalidea 5 3 Tipulidae 5 3 57
5.2.4 Ecosystem Health
The Avoca Valley river ecosystem was in Very Poor Health (Lowland Zone: Very Poor; Slopes Zone: Poor). Fish species count and abundance were dominated by native species but biomass was dominated by aliens; some expected species were absent. Many expected and disturbance-sensitive macroinvertebrate families were absent. The flow regime was in Moderate to Good Condition, with reduced magnitudes of annual flow volumes and low and zero flows, and little change in variability, seasonality and high flows.
Summary Theme assessments are as follows (Table AVO.7): Hydrology Theme • Condition Index SR–HI = 75–99 at selected mainstem locations, indicating Moderate to Good Condition (Lowland Zone: Good, Slopes Zone: Good). • High flows slightly reduced at all sites. • Incidence and duration of low and zero flows showed a Moderate Difference from Reference Condition in upper and middle but a Very Large Difference in the lower reaches. Sites on tributaries were Near Reference Condition. • Flow variation near Reference Condition at all sites. • Seasonality near Reference Condition at all sites, but with a slight shift in the most downstream Lowland Zone sites. • Annual flow volumes in mainstem reduced by 15-30% as means and 30-50% as medians. Fish Theme • Condition Index SR–FI = 46 (CL 30–61), indicating Poor Condition but above average (SR–FI = 37) for all Valleys. Condition differed markedly between Zones (Lowland Zone: Very Poor; Slopes Zone: Good). • Ten species caught, including four alien species. • Predicted native species reduced in the Lowland (69%) and Slopes Zones (14%). • Mean abundance 50 fish per site, mainly native species (68%). • Biomass dominated by alien species (92%). Macroinvertebrate Theme • Condition Index SR–MI = 34 (CL 29–37), indicating Very Poor Condition (both Zones: Very Poor). • Low diversity and proportions of expected families in both Zones. • Many disturbance-sensitive families lost, especially in the Slopes Zone. 58
Table AVO.7: Avoca Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes
Moderate Hydrology Condition Moderate Good Rating to Good Fish Index 46 (30–61) 24 (14–50) 90 (51–97) Rating Poor Very Poor Good
Macroinvertebrate Index 34 (29–37) 34 (31–39) 30 (20–34) Rating Very Poor Very Poor Very Poor
Ecosystem Health Very Very Poor Rating Poor Poor
59
5.3 Border Rivers Valley
5.3.1 Hydrology
Figure BOR.1: Border Rivers Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for sites on the Border Rivers were 71– 100, indicating Moderate to Good Condition (Lowland Zone: Moderate to Good Condition; other Zones: Good Condition).
The Border Rivers catchment is 43,500 km2, or about 4% of the Basin area. It includes rivers rising on the western side of the Great Dividing Range, flowing to the Barwon River, at the head of the Darling Valley. The main tributaries are the Macintyre Brook and the Dumaresq and Macintyre rivers, combining as the Macintyre upstream of Goondiwindi. Downstream, the Macintyre flows through a broad floodplain before entering the upper reaches of the Barwon River near Mungindi. The Moonie River joins the Barwon separately, draining the north-west, and the Severn River drains the south, from New South Wales. There are four major instream storages, the Coolmunda, Glenlyon, Pindara and Rangers Valley Dams, with a combined capacity 60 of 641 GL. Irrigated agriculture occurs throughout the Valley, but is centred on the Macintyre. Cotton is the major crop and horticulture is locally important. There is substantial offstream storage for harvesting high flows. Figure BOR.1 shows values of the Hydrology Index for five selected sites and Table BOR.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams in the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Hydrological condition at the Macintyre/Barwon sites declined from the Upland Zone (Site 5: SR–HI = 100), upstream of regulation and diversion, through the Slopes Zone (Sites 4, Site 3), downstream of storages (SR–HI = 96), to the Lowland Zone (Site 2), which showed a Moderate Difference from Reference Condition (SR–HI = 71). Site 1, at the terminus of the Moonie River, was Near Reference Condition (SR–HI = 96). The indicators show:
• High-Flow Events: Magnitudes were Near Reference Condition upstream (e.g. Site 5), reducing downstream to a Very Large Difference in the Lowland Zone (Site 2), as a result of systematic harvesting. • Low- and Zero-Flow Events: Near Reference Condition. • Variability: Near Reference Condition at most sites. A Moderate Difference was apparent at Site 2, reflecting suppression of high flows. • Seasonality: All sites were Near Reference Condition except Site 4 (Moderate Difference), reflecting the influence of upstream storages. • Gross Volume: Substantial differences (30–75%) from Reference Condition in the Barwon River in the Lowland Zone (e.g. Site 2), and the Boomi and Little Weir Rivers, reflecting the bulk removal of water. Near Reference Condition at other sites. By the time most flows (via the Macintyre) enter the upper Darling Valley, indicators for Gross Volume of annual flow (GV) and High-Flow Events (HFE) consistently show Large to Very Large Differences from Reference Condition. This reflects the volume of water diverted from the system and the effect of differentially harvesting high flows. Low- and zero-flow events are little changed under present management. In general, the flow regime of the Border Rivers Valley is characterised by reductions in the magnitude of high-flow events and annual volumes, and small shifts in seasonality, but there is little change in low- and zero-flow events and variability. Annual volumes and high-flow magnitudes were substantially reduced in the Barwon River in the Lowland Zone, and the Boomi and Little Weir Rivers, but there were minor changes elsewhere.
61
Table BOR.1: Border Rivers Valley: SR Hydrology Index and indicators. Sites are shown in Figure BOR.1.
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Moonie at Gundablouie Lowland 96 76 100 87 97 89 2 Barwon at Mungindi Lowland 71 35 100 75 84 56 3 Macintyre at Goondiwindi Slopes 96 78 100 99 82 92 4 Macintyre at Dam Site Slopes 96 90 92 87 67 80 5 Macintyre at Wallangra Upland 100 100 100 100 100 100
62
5.3.2 Fish
100 Good 80 84 Moderate 60 60 63 55 51 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure BOR.2. Border Rivers Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 63
The Border Rivers Valley fish community was in Moderate Condition. The Upland Zone was dominated by alien species, but otherwise the intrusion of aliens was moderate. Native fish were often abundant, and most predicted native species occurred in each of the four Zones. Nevertheless, species richness had been lost, particularly in the Lowland and Montane Zones, and there was much variation among sites.
Fish were surveyed at 28 sites in four Zones of the Border Rivers Valley in April–May 2005. The total catch was 4,345 fish. Analyses showed a Moderate (–) Difference from Reference Condition: • SR Fish Index (SR–FI) = 60 (CL 55–69) • Many expected native fish were not found (SR–FIe = 57). • Nativeness showed a Moderate (–) Difference from Reference Condition. Figure BOR.2 shows sampling sites, Zones and corresponding SR–FI values, and Table BOR.2 shows Index values, Indicators, Metrics and derived variables. From 7–12 native species and 3–4 alien species were present in each Zone, and 13 native species were recorded in the Valley. Condition in the Montane Zone (SR–FI = 51) was poorer than in the Lowland (SR–FI = 55), Slopes (SR–FI = 63) and Upland Zones (SR–FI = 84). The Upland Zone score should be regarded with caution, as there was variability in Nativeness, species richness, abundance and biomass. There was substantial variation in the Upland and Montane Zones, but less in the Lowland Zone. Despite these differences, community condition compared well with most other Valleys, and the Fish Index score (SR–FI = 60) was third highest among all Valleys. Nativeness varied among Zones, ranging from SR–FIn = 30 in the Montane Zone to SR–FIn = 97 in the Upland Zone, where alien intrusion has been less. Nativeness varied among sites in both of these Zones, reflecting patchiness in alien fish distributions. Expectedness (SR–FIe) was less variable among sites and Zones, indicating similarities in the Reference Condition communities. The Border Rivers Valley community showed a Moderate (–) Difference from Reference Condition (Lowland Zone: Large Difference, Slopes Zone: Moderate (–) Difference, Upland Zone: Near Reference Condition (–), Montane Zone: Large Difference). Some sites in the Upland Zone were near Reference Condition. Across the Valley, 63% of individual fish and 60% of total biomass were native. These are high values, but still demonstrate significant incursions by alien species. Table BOR.2 shows that native species representation in all Zones was below Reference Condition, ranging from 58% (Lowland) to 80% (Upland), with 81% of predicted species across all samples from the Valley. Lowland Zone sites had few native species and were dominated by Carp and Goldfish, with some Eastern gambusia. Montane Zone sites had highly variable numbers of native species, possibly due to human impacts. These sites supported Goldfish and Eastern gambusia, but not Carp, which are constrained by instream barriers that block upstream movements. Surprisingly, Silver perch were not detected in Border Valley catches. The proportion of native species among fish from the Upland Zone was similar to that in other Zones, but the proportion of native individuals was much lower. This was reflected in the biomass data, and resulted from large catches of Eastern gambusia at two sites. 64
Table BOR.3 shows the abundances of species in the Valley Zones and compares them with the predicted Reference Condition. Noteworthy among the missing species are Silver perch and River blackfish. Across the Valley, over 20% of fish showed Abnormalities, driven mainly by extreme numbers (79%) in one Montane Zone site and high levels (12%) in Lowland Zone sites. Macro- and Mega- carnivore species were common in all Zones.
Table BOR.2: Border Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland Montane
60 55 63 84 51 Fish Index (55–69) (50–63) (55–83) (61–100) (32–68) 57 51 58 66 59 Expectedness Indicator (52–64) (51–56) (52–76) (66–97) (43–59) 60 57 64 97 30 Nativeness Indicator (50–72) (42–68) (53–94) (37–100) (9–77)
Metrics Total species 18 10 12 15 11 Native (RC–F) species 13 7 9 12 7 Predicted (RC–F) species count 16 12 15 15 11 Alien species 5 3 3 3 4 Caught/Predicted native species (%) 81 58 60 80 64
Numbers of fish Mean fish per site all species 155 118 104 222 176 Native individuals (%) 63 75 84 36 76
Fish biomass Total biomass/site all species (g) 9,322 13,231 11,838 4,596 7,623 Mean native biomass/fish (g) 57 65 94 23 49 Mean alien biomass/fish (g) 65 250 216 19 25 Biomass native (%) 60 43 69 40 86
65
Table BOR.3: Border Rivers Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown as numbers; species not predicted shown as blanks
Native species Zone Lowland Slopes Upland Montane Total
Australian smelt 0 4 62 0 66 Bony herring 542 188 3 733 Carp gudgeons 7 295 387 899 1,588 Darling River hardyhead 0 0 1 1 Flat-headed gudgeon 0 0 Freshwater catfish 1 12 26 2 41 Golden perch 44 14 4 3 65 Mountain galaxias 0 2 2 4 Murray cod 6 32 6 28 72 Murray–Darling rainbowfish 5 49 22 0 76 Olive perchlet 0 0 3 3 River blackfish 0 0 0 Silver perch 0 0 0 0 0 Southern purple-spotted gudgeon 0 0 1 1 2 Spangled perch 13 7 6 26 Un-specked hardyhead 0 12 38 50
Alien species
Carp 151 39 31 Eastern gambusia 46 61 940 202 Goldfish 13 18 25 40 Rainbow trout 1 Redfin perch 51 66
5.3.3 Macroinvertebrates
100 Good 80 70 66 69 Moderate 60 46 46 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure BOR.3: Border Rivers Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 67
The Border Rivers macroinvertebrate community was in Moderate Condition, with the Lowland and Slopes Zones in better condition than the Upland and Montane Zones, having more ‘expected’ families. The Upland and Montane Zones were in Poor Condition, with depleted communities that had lost most of their disturbance-sensitive families.
Thirty four sites were surveyed across four Zones of the Border Rivers Valley in May 2005, yielding 7,367 macroinvertebrates in 63 families (44% of Basin families). Analyses showed a Moderate Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 66 (CL 58–75). • Moderate to high proportion of expected families (Filters OE = 38). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 89). The Border Rivers Valley had the highest SR–MI score of all Valleys. The Lowland and Slopes Zone communities showed a Moderate Difference from Reference Condition (SR–MI = 69, 70, respectively), and the Upland and Montane Zones showed a Large Difference (SR–MI = 46). Wide confidence intervals (20–30 points) in all Zones indicate substantial variation in condition among sites. Figure BOR.3 shows sampling sites, Zones and SR–MI values, and Table BOR.4 shows metrics and derived variables. Sixty six percent of expected families were found in the Valley, and family richness was less than Reference Condition at more than 40% of sites. Diversity was high (average 26 families per site), and least in Lowland Zone sites (average 22 families per site). Most (90%) of the Valley fauna was in the Slopes Zone (cf. 68–75% for the Lowland, Upland and Montane Zones). Table BOR.5 shows that expected (Filters OE) scores indicated some loss of expected families, with significant variation among sites in the Upland and Montane Zones. No sites had a low Filters OE score, and 12 of 27 sites in the Lowland and Slopes Zones had high scores. Filters SIGNAL OE scores were near Reference Condition in the Lowland and Slopes Zones, but less in the Upland and Montane Zones. Most sites in the latter Zones had impoverished communities, lacking some disturbance-sensitive families. Table BOR.6 shows ‘common’ and ‘rare’ families. The 19 common families included snails (Ancylidae, Lymnaeidae), prawns (Palaemonidae) and 16 families of aquatic insects. The palaemonid prawn Macrobrachium australiense, for example, is part of the diet of many fish. Rare families (below the 10th percentile for all Valleys) included isopod crustaceans (Phreato- icidae) and a variety of insects. 68
Table BOR.4: Border Rivers Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 66 69 70 46 46 (58–75) (56–87) (63–85) (32–54) (39–74) Metrics Filters OE 38 38 39 30 28 (34–42) (30–45) (36–47) (21–35) (23–43) Filters SIGNAL OE 89 97 91 78 83 (87–92) (89–100) (86–93) (74–84) (82–84) Families Families per site 26 22 28 23 28 minimum – maximum 12–37 12–29 21–35 19–33 22–37 Total families 63 42 57 44 46
Table BOR.5: Border Rivers Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 34 11 16 4 3
Filters OE High 13 5 7 1 Medium 21 6 9 4 2 Low
Filters SIGNAL OE High 1 1 Medium 29 10 14 2 3 Low 4 2 2
69
Table BOR.6: Border Rivers Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 11 16 4 3 34 Number of families sampled 43 57 44 47 63 Percent of families in Basin 39.4 46.7 39.3 47.5 44.1 Percent of families in Valley 68 90 70 75 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY
Common Corixidae 100 100 100 100 100 Baetidae 91 94 100 100 94 Notonectidae 91 100 75 100 94 Palaemonidae 100 75 100 67 85 Ancylidae 73 69 75 100 74 Coenagrionidae 55 75 100 67 71 Culicidae 64 56 100 67 65 Gerridae 91 63 25 62 Isostictidae 45 88 56 Pleidae 18 69 50 33 47 Gomphidae 18 63 25 67 44 Staphylinidae 45 56 25 44 Ecnomidae 55 50 41 Hydrometridae 45 38 32 Mesoveliidae 36 31 50 32 Protoneuridae 18 25 75 33 29 Lymnaeidae 38 25 33 24 Naucoridae 9 31 18 Hebridae 19 33 12 Rare Hydropsychidae 9 25 6 Scirtidae 6 33 6 Gelastocoridae 6 3 Haliplidae 6 3 Lestidae 33 3 Phreatoicidae 33 3 Psychodidae 6 3 Simuliidae 25 3
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5.3.4 Ecosystem Health
The Border Rivers Valley river ecosystem was in Moderate Health (Lowland, Upland Zones: Moderate; Slopes Zone: Good; Montane Zone: Poor). Fish species count, biomass and abundance were dominated by native fish, but some expected species were absent. Some expected and disturbance-sensitive macroinvertebrate families were absent in Lowland and Slopes Zones, and many were absent in the Upland and Montane Zones. There were reduced annual flow volumes and high-flow magnitudes in the Barwon River in the Lowland Zone but minor hydrological changes elsewhere.
Summary Theme assessments are as follows (Table BOR.7): Hydrology Theme • Condition Index SR–HI = 71–100 at selected mainstem locations, indicating Moderate to Good Condition (Lowland Zone: Moderate to Good, Slopes and Upland Zones: Good). • High flows were Near Reference Condition upstream, progressing to a Very Large Difference from Reference Condition downstream. • Incidence and duration of low and zero flows were Near Reference Condition. • Flow variability slightly reduced or unchanged. • Seasonality little changed at most sites. • Annual flow volumes were significantly reduced in the Barwon River in the Lowland Zone but Near Reference Condition elsewhere. Fish Theme • Condition Index SR–FI = 60 (CL 55–69), indicating Moderate Condition (third highest for all Valleys). Condition varied across Zones (Lowland Zone: Poor; Slopes Zone: Moderate; Upland Zone: Good; Montane Zone: Poor). • Eighteen species caught, including five alien species. • Predicted native species reduced in the Lowland (42%), Slopes (40%), Upland (20%) and Montane Zones (36%). • Mean abundance 155 fish per site, mainly native species (63%). • Biomass dominated by native species (60%). Macroinvertebrate Theme • Condition Index SR–MI = 66 (CL 58–75), indicating Moderate Condition (Lowland, Slopes Zones: Moderate; Upland, Montane Zones: Poor). • Moderate to high diversity and proportions of expected families in Lowland and Slopes Zones. • Low to moderate proportions of expected families in Upland and Montane Zones. • Disturbance-sensitive families reduced in the Slopes Zone and further reduced in the Upland and Montane Zones. 71
Table BOR.7: Border Rivers Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland Montane
Moderate Moderate Hydrology Condition Good Good Good Rating to Good to Good Fish Index 60 (55–69) 55 (50–63) 63 (55–83) 84 (61–100) 51 (32–68) Rating Moderate Poor Moderate Good Poor
Macroinvertebrate Index 66 (58–75) 69 (56–87) 70 (63–85) 46 (32–54) 46 (39–74) Rating Moderate Moderate Moderate Poor Poor
Ecosystem Health Moderate Moderate Good Moderate Poor Rating
72
5.4 Broken Valley
5.4.1 Hydrology
Figure BRO.1: Broken Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Condition of the Broken Valley was Moderate to Good (Lowlwand Zone: Moderate to Good; Slopes Zone: Good). Hydrology Index scores were 41–100, indicating Near Reference Condition above the influence of offstream storages, and Moderate to Large Differences from Reference Condition downstream.
The Broken River rises in the Great Dividing Range east of Mansfield and flows west then north to Benalla, then west to join the Goulburn River above Shepparton. A substantial distributary, Broken Creek, flows north-west from the river downstream of Benalla, joining the Murray at the downstream end of Barmah Forest. There is one instream storage, Lake Nillahcootie (40 GL). Lake Mokoan, a wetland near Benalla, has been used as an offstream storage (26 GL) to augment irrigation diversions in summer and autumn. Water was diverted to Lake Mokoan from the Broken River upstream of Benalla at Broken Weir and released to the river downstream of 73
Benalla, upstream of Casey’s Weir and Broken Creek. Water is also diverted into Broken Creek to enhance irrigation and stock and domestic supplies. Figure BRO.1 shows values of the Hydrology Index for five selected sites and Table BRO.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams across the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at two sites upstream of the diversion to Lake Mokoan was Near Reference (SR–HI = 95–100). Index scores for the Broken River between the offtake of water to Lake Mokoan and its return downstream showed a Large Difference from Reference Condition (SR–HI = 41). The remaining sites showed a Moderate Difference from Reference Condition. The indicators show:
• High-Flow Events: High flows in the Broken River were reduced by 50% downstream of Broken Weir, where water is diverted to Lake Mokoan. Values indicated Near Reference Condition at Site 5, Large Difference from Reference Condition at Sites 3–4, reflecting offstream storage, and Near Reference Condition upstream on the Broken and at other sites. • Low- and Zero-Flow Events: The frequency of low- and zero-flow periods was increased in the middle and lower Broken River (Large to Extreme Differences from Reference Condition at Sites 2 and 3), but remained Near Reference Condition at upstream sites. Most Lowland Zone tributaries had Large to Moderate Differences from Reference Condition, and all Slopes Zones sites were Near Reference Condition. • Variability: Near Reference Condition at all sites except Site 3, which showed a Moderate Difference from Reference Condition, reflecting redirection of flows to offstream storage. • Seasonality: Large to Very Large Differences from Reference Condition at Sites 3–4. Moderate Differences from Reference Condition on Boosey and Broken Creeks in the Lowland Zone. Near Reference elsewhere. • Gross Volume: Mean annual volumes reduced by 8–16% in the Broken Lowland Zone, with median annual flow reduced by 75% at Site 5. Boosey and Broken Creeks experienced 73–100% and 25–30% reductions in mean and median annual flow volumes, respectively. Near Reference Condition at most other sites. Site 3, on the Broken River downstream of the Lake Mokoan offtake and upstream of the return channel, has experienced most change, with all indicators showing substantial reductions. Operation of the offstream storage (storage in winter-spring, release in summer-autumn) is reflected in changes to indicators at Sites 3–4, downstream of the offtake. High-Flow Events (HFE), Low- and Zero-Flow Events (LZFE), and Seasonality (S) are clearly affected. The Gross Volume of annual flow (GV) is unchanged at Site 4, indicating that flow changes are caused by regulation rather than diversion. There is a substantial distance (>50 km) between Site 4 and the Goulburn confluence, and any diversions in that reach are not accounted for in this assessment. The storage at Lake Nillahcootie, upstream of Site 5, appears to have little effect on the hydrology of the Broken River. Flow in Broken Creek is influenced by diversions from the Broken River and, to a lesser extent, by irrigation return water. In general, the Broken Valley flow regime is characterised by reduced annual volumes and high- flow events and changes to low flows and seasonality in the Broken mainstem and two Lowland Zone tributaries, and minimal changes elsewhere. 74
Table BRO.1: Broken Valley: SR Hydrology Index and indicators. Sites are shown in Figure BRO.1. US: upstream; DS downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Broken Creek US Boosey Ck Lowland 79 95 60 80 76 54 2 Broken River DS Casey’s Weir Lowland 62 45 59 86 36 100 3 Broken River US Casey’s Weir Lowland 41 49 12 69 46 54 4 Broken River US Broken Weir Lowland 95 87 80 94 82 99 5 Broken River US Swanpool Slopes 100 100 99 98 95 97
75
5.4.2 Fish
100 Good 80 Moderate 60 60 Poor 40 35 26 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure BRO.2: Broken Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 76
The Broken Valley fish community was in Very Poor Condition, with the Lowland Zone community in Very Poor Condition and the Slopes Zone in Moderate Condition. Fewer than half of the predicted native species were found. Although native fish were numerically dominant, these were small species and only one-third of the total biomass. Substantial species richness had been lost, and the biomass was dominated by alien species.
Fish in the Broken Valley were surveyed in November–December 2004. Nineteen sites were sampled in two Zones, yielding 1,816 fish. Analyses indicated a Very Large (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 35 (CL 25– 50). • Less than half the predicted native species were found, particularly in the Lowland Zone. • Nativeness showed a Large (±) Difference from Reference Condition. Figure BRO.2 shows sampling sites, Zones and corresponding SR–FI values, and Table BRO.2 shows Index values, Indicators, Metrics and derived variables. Eleven native species and six alien species were recorded in the Valley, with eight native species in each Zone. The SR Fish Index score placed the Broken Valley community near the average for all Valleys, with 12 communities in better condition and 10 in worse condition. The Lowland Zone community was in poorer condition (SR–FI = 26: Very Poor) than the Slopes Zone community (SR–FI = 60: Moderate), where Nativeness was high (SR–Fn = 96: Near Reference Condition). Index values in both Zones were variable. The Valley community showed a Very Large (+) Difference from Reference Condition (Lowland Zone: Very Large (–) Difference, Slopes Zone: Moderate (–) Difference. Throughout the Lowland and Slopes Zones, the numbers of native species in samples were 38% and 53%, respectively, of those predicted under Reference Condition. Expectedness was correspondingly low (SR–Fe = 28, 40, respectively). Nativeness was low in the Lowland Zone (SR–Fn = 32), where native species had been lost, but in the Slopes Zone there were high proportions of native species and biomass (SR–Fn = 96). The distributions of native fish in the Lowland and Slopes Zones were patchy, causing variable scores. Carp and Goldfish were common in the Lowland Zone, and Redfin perch and Brown trout were common in the Slopes Zone. Native fish made up 65% of the species richness and 74% of total individuals, but only 36% of total biomass. This indicated that alien fish, particularly Redfin perch and Carp, were considerably larger than the native species (average 184 g cf. 36 g). Most of the native species were small fish such as Mountain galaxias and Pygmy perch. Table BRO.3 shows the abundances of native species in the two Zones. Trout cod and Silver perch were not caught, but were predicted to be common under Reference Condition. Other species not caught, but expected to be rare or moderately rare in one or more Zones under Reference Condition, included Trout cod, Murray cod, Golden perch, Macquarie perch, Southern purple-spotted gudgeon and Silver perch. Flat-headed galaxias (Galaxias rostratus) was not recorded; this was predicted to be an occasional species in the Lowland Zone, but it lives mainly in floodplain wetlands that are not sampled under the SRA Protocol. In the Lowland Zone, 4.5% of fish showed Abnormalities, but none were recorded in the Slopes Zone. Two Intolerant species were recorded in the Lowland Zone and four in the Slopes Zone. 77
Macro-carnivore species were abundant in both Zones, but Mega-carnivores were recorded only in the Lowland Zone.
Table BRO.2: Broken Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits) Zone Valley Lowland Slopes
Fish Index 35 (25–50) 26 (14–43) 60 (41–72) Expectedness Indicator 31 (25–41) 28 (21–39) 40 (35–52) Nativeness Indicator 48 (33–71) 32 (21–60) 96 (44–100) Metrics Total species 17 13 12 Native (RC–F) species 11 8 8 Predicted RC–F species count 23 21 15 Alien species 6 5 4 Caught/Predicted native species (%) 48 38 53 Numbers of fish Mean fish per site all species 96 84 106 Native individuals (%) 74 80 70 Fish biomass Total biomass/site all species (g) 7,046 13,753 1,010 Mean native biomass/fish (g) 36 70 8 Mean alien biomass/fish (g) 184 537 14 Biomass native (%) 36 34 57
78
Table BRO.3: Broken Valley: numbers of native fish by Zone. Predicted species (RC–F list) are shown as numbers; species not predicted are shown as blanks
Native species Zone Total Lowland Slopes
Australian smelt 59 8 67 Bony herring 0 0 Carp gudgeons 39 1 40 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 0 0 0 Freshwater catfish 0 0 Riffle galaxias 0 18 18 Golden perch 5 0 5 Macquarie perch 0 0 0 Mountain galaxias 273 273 Murray cod 12 0 12 Murray hardyhead 0 0 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 23 0 23 Obscure galaxias 9 21 30 River blackfish 18 125 143 Short-headed lamprey 0 0 Silver perch 0 0 Southern purple-spotted gudgeon 0 0 Southern pygmy perch 442 297 739 Trout cod 0 0 0 Two–spined blackfish 1 1 Un-specked hardyhead 0 0
Alien species
Brown trout 3 10 13 Carp 87 17 104 Eastern gambusia 13 13 Goldfish 38 38 Rainbow trout 14 14 Redfin perch 10 273 283
79
5.4.3 Macroinvertebrates
100 Good 80 Moderate 60 54 51 49 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure BRO.3: Broken Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 80
The Broken Valley macroinvertebrate community was in Poor Condition throughout, lacking some ‘expected’ and disturbance-sensitive families.
Thirty five sites were surveyed across two Zones of the Broken Valley in March 2005, yielding 10,249 macroinvertebrates in 78 families (57% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 51 (CL 46–53). • Low to moderate proportion of expected families (Filters OE = 28). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 94). SR–MI for the Broken Valley is in the mid–range for all Valleys. The Lowland and Slopes Zone communities showed a Large Difference from Reference Condition (SR–MI = 49, 54, respectively). Confidence intervals in both Zones indicate moderate variation in condition among sites. Figure BRO.3 shows sampling sites, Zones and SR–MI values, and Table BRO.4 shows metrics and derived variables. Seventy five percent of expected families were recorded in the Valley, and family richness at all sites was less than Reference Condition. Diversity was moderate to high (average 24 families per site), with some Slopes Zone sites being particularly diverse (average 31 families per site). Most (84%) of the Valley fauna was in the Slopes Zone (cf. 73% for the Lowland Zone). Table BRO.5 shows that Expectedness (Filters OE) scores indicated moderate to major losses of expected families, with some variation among sites. None of the 35 sites had a high Filters OE score. Filters SIGNAL OE scores were near Reference Condition at four Slopes Zone sites, and one site in each Zone had a low Filters SIGNAL OE score. The fauna at most sites was depleted and lacking disturbance–sensitive families. Table BRO.6 shows ‘common’ and ‘rare’ families. Seven common families included longhorn caddis (Leptoceridae), mayflies (Baetidae), snails (Ancylidae), whirligig beetles (Gyrinidae) and water measurers (Hydrometridae). The 22 rare families included 17 insect families. 81
Table BRO.4: Broken Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Index 51 49 54 SR–MI (46–53) (44–51) (48–63) Metrics 28 27 29 Filters OE (26–29) (25–28) (26–33) 94 91 96 Filters SIGNAL OE (87–97) (84–94) (90–109) Families Families per site 24 20 31 minimum – maximum 13–40 13–30 23–40 Total families 78 56 69
Table BRO.5: Broken Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes
Number of sites 35 24 11
Filters OE High Medium 34 23 11 Low 1 1 Filters SIGNAL OE High 5 1 4 Medium 28 22 6 Low 2 1 1
82
Table BRO.6: Broken Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 24 11 35 Number of families sampled 60 69 82 Percent of families in Basin 55.0 56.6 57.3 Percent of families in Valley 73 84 100
Percent of sites by Zone Lowland Slopes VALLEY
Common Leptoceridae 100 100 100 Baetidae 96 91 94 Ancylidae 75 64 71 Gyrinidae 50 55 51 Dixidae 13 100 40 Hydrometridae 21 27 23 Perthiidae 17 11 Rare Acarina 21 82 40 Ceratopogonidae 25 64 37 Athericidae 4 9 6 Ptilodactylidae 18 6 Synlestidae 4 9 6 Atriplectididae 4 3 Conchostraca 4 3 Eusiridae 9 3 Eustheniidae 9 3 Gelastocoridae 9 3 Glossosomatidae 9 3 Haliplidae 4 3 Helicophidae 9 3 Isopoda 4 3 Lestidae 4 3 Limnephilidae 9 3 Megapodagrionidae 4 3 Muscidae 4 3 Oniscigastridae 9 3 Paramelitidae 4 3 Tabanidae 9 3 Thaumaleidae 9 3 83
5.4.4 Ecosystem Health
The Broken Valley river ecosystem was in Very Poor Health (Lowland Zone: Very Poor; Slopes Zone: Moderate). Fish numbers were dominated by native species, but many expected species were absent and biomass was dominated by aliens. Many expected and some disturbance-sensitive macroinvertebrate families were absent. There were reduced magnitudes of annual and high flows and changes to low flows and seasonality in the mainstem and two tributaries in the Lowland Zone, but minimal changes elsewhere.
Summary Theme assessments are as follows (Table BRO.7): Hydrology Theme • Condition Index SR–HI = 41–100 at selected locations, indicating Near Reference Condition upstream of storages and Moderate to Large Differences from Reference Condition at downstream sites. Condition was Moderate to Good. • HFE was reduced by 50% downstream of Broken Weir and Near Reference Condition at other sites. • Values of LZFE were highly altered in the middle and lower Broken River (Large to Extreme Differences from Reference Condition), but Near Reference Condition upstream. Most Lowland Zone tributaries showed Large to Moderate Differences from Reference Condition, and all Slopes Zones sites were Near Reference Condition. • Variability showed a Moderate Difference from Reference Condition in the middle Broken, and was Near Reference Condition at other sites. • Seasonality showed Large to Very Large Differences from Reference Condition in the middle Broken River, a Moderate Difference on Boosey and Broken Creeks in the Lowland Zone and Near Reference Condition elsewhere. • Mean annual flow reduced by 8-16% in the Broken Lowland Zone and median annual flow reduced by up to 75%. Boosey and Broken Creeks showed 73-100% and 25-30% reduction in mean and median annual flow volumes, respectively. Annual volumes were Near Reference Condition at nearly all other sites. Fish Theme • Condition Index SR–FI = 35 (CL 25–50), indicating Very Poor Condition, near the average (SR–FI = 37) for all Valleys. Condition varied among Zones (Lowland Zone: Very Poor; Slopes Zone: Moderate). • Seventeen species caught, including six alien species. • Predicted native species reduced in the Lowland (62%) and Slopes Zones (47%). • Mean abundance 96 fish per site, mainly native species (74%). • Biomass dominated by alien species (64%). Macroinvertebrate Theme • Condition Index SR–MI = 51 (CL 46–53), indicating Poor Condition (both Zones: Poor). • Moderate (occasionally high) diversity but low to very low proportions of expected families. • Expected disturbance-sensitive families reduced at most sites. 84
Table BRO.7: Broken Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley
Zone
Valley Lowland Slopes
Hydrology Condition Moderate to Moderate Good Rating Good to Good
Fish Index 35 (25–50) 26 (14–43) 60 (41–72) Rating Very Poor Very Poor Moderate
Macroinvertebrate Index 51 (46–53) 49 (44–51) 54 (48–63) Rating Poor Poor Poor
Ecosystem Health Very Very Moderate Rating Poor Poor
85
5.5 Campaspe Valley
5.5.1 Hydrology
Figure CAM.1: Campaspe Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for the Campaspe River were 58–99, indicating Moderate Condition (Lowland Zone: Poor to Moderate; Slopes Zone: Moderate; Upland Zone: Good).
The Campaspe Valley is about 4,000 km2, or <0.5% of the Basin area. The Campaspe rises in the Great Dividing Range near Woodend and flows north to the Murray at Echuca. The main instream storage is Lake Eppalock (304 GL), near Bendigo and the junction with the Coliban River. There are three storages on the Coliban, namely the Upper Coliban (38 GL), Lauriston (20 GL) and Malmsbury (18 GL). Diversions for irrigation occur at Rochester and downstream toward the Murray. The Coliban provides urban supplies for Bendigo and large towns in the upper catchment, and some irrigation. 86
Figure CAM.1 shows values of the Hydrology Index for five selected sites and Table CAM.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at two sites downstream of Lake Eppalock showed Moderate to Large Differences from Reference Condition (SR–HI = 58, 63). In the Campaspe Upland Zone, Site 4 was in Near Reference Condition (SR–HI = 99), but inflowing streams upstream of Lake Eppalock showed a Moderate Difference (SR–HI = 78, 71). The indicators show:
• High-Flow Events: Reduced by up to 60% on the Coliban and the Campaspe downstream of Lake Eppalock. Near Reference Condition at Sites 3–4; Large Difference from Reference Condition at Sites 1–2, due to regulation at Eppalock. Site 5 showed a 20% reduction due to Upper Coliban, Lauriston and Malmsbury reservoirs and associated offtakes. • Low- and Zero-Flow Events: Very Large Differences to Near Reference Condition in the Lowland Zone, and Near Reference Condition in the Upland Zone. Very Large Difference at Sites 2–3; a Moderate Difference at Site 5. • Variability: Near Reference Condition, except in the Campaspe Lowland Zone where monthly variability was 63% of the Reference Condition value. Site 1 showed a Moderate Difference. • Seasonality: Sites upstream of Eppalock (e.g. Sites 3–5) were Near Reference Condition, but there were Very Large (Site 2) to Moderate Differences (Site 1) downstream. • Gross Volume: Near Reference Condition except on the middle and lower Coliban and the lower Campaspe, where mean and median volumes were 55–60% and 21–45% of Reference Condition values, respectively. Site 1 showed a Very Large Difference from Reference Condition and Site 5, on the Coliban, showed a Moderate Difference. The remaining three sites were Near Reference Condition. The Coliban (Site 5), upstream of Eppalock but downstream of other storages and diversions, showed substantial changes in GV and LZFE and smaller differences in other indicators. In the Campaspe Upland Zone (Site 4), the only indicator to show some modification was GV, possibly due to runoff interception by farm dams. On the Campaspe downstream of Eppalock but upstream of the major diversions (Site 2), HFE, LZFE and S were substantially modified but GV less so. Downstream of the diversions (Site 1), GV and HFE were significantly changed. LZFE and S were considerably higher than at Site 2, perhaps due to transfers from the Goulburn via the Waranga Western Channel. ,On the Coliban and lower Campaspe volumes of annual flows and high flow events were reduced and variability and seasonality also were affected. In general, the flow regime of the remainder of the Campaspe River system was Near Reference Condition Saline groundwater is a threat to the ecosystem of the lower Campaspe (Cottingham et al. 2008), and extended periods of low- and zero-flow could amplify the effects on fish and macroinvertebrate biodiversity.
87
Table CAM.1: Campaspe Valley: SR Hydrology Index and indicators. Sites are shown in Figure CAM.1. US: upstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Campaspe at Echuca Lowland 63 48 84 63 60 38 2 Campaspe at Elmore Lowland 58 41 39 94 34 80 3 Campaspe US Lake Eppalock Slopes 78 99 36 96 88 86 4 Campaspe at Woodend Upland 99 99 100 97 99 80 5 Coliban US Lake Eppalock Slopes 71 80 59 82 80 61
88
5.5.2 Fish
100 Good 80 Moderate 60 Poor 40 Very Poor 20 17 5 Extremely Poor 0 2 1 Valley lowland slopes upland
Figure CAM.2: Campaspe Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 89
The Campaspe Valley fish community was in Extremely Poor Condition. The community had lost most of its native species richness, and alien species contributed most of the biomass and abundance.
Fish in 21 sites across three altitudinal Zones of the Campaspe Valley were surveyed in November–December 2006 and January 2007, yielding 1,362 fish. Analyses showed an Extreme Difference from Reference Condition:
• SR Fish Index (SR–FI) = 5 (CL 2–17). • Expectedness showed an Extreme Difference from Reference Condition. • Nativeness showed a Very Large (±) Difference from Reference Condition. • Native fish were 21% of the catch and only 7% of total biomass. • Sixty four percent of 22 predicted native (RC–F) species were missing. Figure CAM.2 shows sampling sites, Zones and corresponding SR–FI values, and Table CAM.2 shows Index values, Indicators, Metrics and derived variables. Eight native and eight alien species were recorded in the Valley, but there were only two native species in the Slopes and Upland Zones. The Campaspe Valley Fish Index score was equal lowest, with the Goulburn, among all Valleys. Almost two–thirds of the predicted native species were not found. Average numbers of fish per site were very low in Lowland (33) and Upland Zone (29) sites, but higher in the Slopes Zone (132). Native fish numbers ranged from only 15% (Slopes) to 41% (Upland) of total numbers. In the Slopes and Upland Zones, catches of native and alien fish, hence Nativeness, varied substantially. The Campaspe Valley and its three Zones showed an Extreme Difference from Reference Condition; the Upland Zone showed a Very Large (±) Difference. Only one of 21 sites, in the Lowland Zone, had more than three native species; 14 sites had only one or none. Amongst the few native fish, almost all were small (e.g. Australian smelt, Galaxias species, gudgeons and Pygmy perch), apart from a few Murray cod and Golden perch. Low proportions of native fish in Slopes and Upland Zone catches, with the larger body size of alien fish like Carp, Brown trout, Redfin perch and Tench, resulted in a (rounded) zero native proportion of total biomass in the Slopes and Upland Zones, and only 7% for the Valley. Table CAM.3 shows that River blackfish, Macquarie perch, Obscure galaxias and Trout cod were not caught in Zones where they were predicted to be common under Reference Condition. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Bony herring, Freshwater catfish, Murray cod and Silver perch, and several small, less well-known species. Abnormalities were visible on over 4% of fish in Upland Zone sites, but no more than 1% in the other two Zones. Two Intolerant species were found. No Mega-carnivore species were caught at Slopes or Upland Zone sites. 90
Table CAM.2: Campaspe Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Fish Index 5 (2–17) 2 (0–8) 1 (0–24) 17 (6–24) Expectedness Indicator 15 (11–18) 12 (6–12) 9 (9–19) 21 (21–21) Nativeness Indicator 22 (15–43) 19 (8–29) 17 (8–57) 32 (14–89) Metric Total species 16 10 8 7 Native species 8 5 2 2 Predicted RC–F species count 22 21 9 8 Alien species 8 5 6 5 Caught/Predicted native species (%) 36 24 22 25 Numbers of fish Mean fish per site 65 33 132 29 Native individuals (%) 21 29 15 41 Fish biomass Biomass/site all species (g) 13,298 18,881 15,546 5,467 Mean native biomass/fish (g) 66 271 3 1 Mean alien biomass/fish (g) 243 688 138 321 Biomass native (%) 7 14 0 0
91
Table CAM.3: Campaspe Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Lowland Slopes Upland Total
Australian smelt 12 0 12 Bony herring 0 0 Carp gudgeons 8 8 Congolli 0 0 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 39 20 0 59 Freshwater catfish 0 0 Golden perch 7 0 7 Macquarie perch 0 0 0 0 Mountain galaxias 78 78 Murray cod 3 0 0 3 Murray hardyhead 0 0 Flat-headed galaxias 0 0 Murray–Darling rainbowfish 0 0 Obscure galaxias 0 119 0 119 River blackfish 0 0 0 0 Short-headed lamprey 0 0 Silver perch 0 0 Southern purple-spotted gudgeon 0 0 Southern pygmy perch 0 0 6 6 Trout cod 0 0 0 0 Un-specked hardyhead 0 0
Alien species
Brown trout 1 1 45 47 Carp 88 297 385 Eastern gambusia 8 394 19 421 Goldfish 8 2 10 Redfin perch 60 38 27 125 Roach 2 2 Tench 54 26 80
92
5.5.3 Macroinvertebrates
100 Good 80 Moderate 60 48 Poor 40 41 39 33 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure CAM.3: Campaspe Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 93
The Campaspe Valley macroinvertebrate community was in Poor Condition, with all Zones in Poor to Very Poor Condition. Most Slopes and Upland Zone communities were depleted and had lost many disturbance-sensitive families.
Thirty five sites were surveyed across three Zones of the Campaspe Valley in April 2005, yielding 11,819 macroinvertebrates in 78 families (55% of Basin families). Analyses showed a Large (–) Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 41 (CL 36–45). • Moderate to low proportion of expected families (Filters OE = 26). • SIGNAL OE score substantially lower than Reference Condition (Filters SIGNAL OE = 80). SR–MI for the Campaspe Valley is the equal third lowest score of all Valleys (cf. Castlereagh). The Lowland Zone community showed a Large Difference from Reference Condition (SR–MI = 48), and Slopes and Upland Zones showed a Very Large (+) Difference (SR–MI = 33, 39, respectively). Wide confidence intervals for SR–MI (19 points) showed substantial variation in condition among sites in the Upland Zone. Figure CAM.3 shows sampling sites, Zones and SR–MI values, and Table CAM.4 shows metrics and derived variables. Most (78%) of the expected families were recorded in the Valley, but family richness was less than Reference Condition at all sites. Diversity was moderate to high in all Zones (average 25 families per site). Table CAM.5 shows that Expectedness (Filters OE) scores indicated substantial losses of expected families. None of 35 sites had a high Filters OE score, and four sites had a low Filters OE score. Filters SIGNAL OE scores were consistently low for all Zones, with a high proportion of sites (10 of 13) in the Slope Zone having a low Filters SIGNAL OE score. Most Slopes and Upland Zones had impoverished faunas, lacking some disturbance-sensitive families. Table CAM.6 shows ‘common’ and ‘rare’ families. Fourteen common families included limpets and snails (Ancylidae, Physidae), amphipods (Ceinidae), mites (Acarina), damselflies (Coenagri- onidae, Lestidae) and other aquatic insects. The 27 rare families included caddisflies and other aquatic insects. 94
Table CAM.4: Campaspe Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 41 48 33 39 (36–45) (39–53) (25–42) (28–47) Metrics Filters OE 26 28 25 25 (23–28) (23–32) (21–28) (19–29) Filers SIGNAL OE 80 85 73 79 (76–83) (81–91) (69–78) (70–89) Families Families per site 25 24 25 25 minimum – maximum 15–34 17–29 15–34 18–34 Total families 78 47 57 61
Table CAM.5: Campaspe Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 35 12 13 10
Filters OE High Medium 31 12 12 7 Low 4 1 3 Filters SIGNAL OE High 1 1 Medium 17 10 3 4 Low 17 2 10 5
95
Table CAM.6: Campaspe Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown.
Sites sampled 12 13 10 35 Number of families sampled 47 61 62 83 Percent of families in Basin 40.9 46.6 53.0 54.6 Percent of families in Valley 57 73 75 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Leptoceridae 100 100 100 100 Ceinidae 83 100 90 91 Acarina 92 77 100 89 Veliidae 92 85 90 89 Coenagrionidae 92 69 60 74 Gyrinidae 92 77 40 71 Planorbidae 75 54 90 71 Ancylidae 92 46 60 66 Physidae 50 69 80 66 Hydroptilidae 58 54 50 54 Hirudinea 33 23 70 40 Calamoceratidae 50 23 20 31 Lestidae 38 60 31 Nepidae 25 46 10 29 Rare Caenidae 33 54 30 40 Ceratopogonidae 25 46 40 37 Palaemonidae 25 9 Synlestidae 20 6 Atriplectididae 10 3 Austroperlidae 10 3 Calocidae 10 3 Conoesucidae 10 3 Gastropoda 8 3 Gelastocoridae 8 3 Glossiphoniidae 8 3 Gordiidae 8 3 Haliplidae 10 3 Helicopsychidae 10 3 Limnephilidae 10 3 Megapodagrionidae 8 3 Muscidae 8 3 Nemertea 8 3 Philopotamidae 10 3 Philorheithridae 10 3 Pleidae 8 3 Podonominae 10 3 Protoneuridae 8 3 Psephenidae 10 3 Richardsonianidae 8 3 Sialidae 8 3
96
5.5.4 Ecosystem Health
The Campaspe Valley river ecosystem was in Very Poor Health (Lowland Zone: Very Poor; Slopes, Upland Zones: Extremely Poor). Fish abundance and biomass were dominated by alien species, and most expected species were absent. Many expected and disturbance-sensitive macroinvertebrate families were absent. The flow regime was Near Reference Condition except in the Coliban and lower Campaspe where volumes of annual flows and high flow events were reduced and variability and seasonality also were affected.
Summary Theme assessments are as follows (Table CAM.7): Hydrology Theme • Condition Index SR–HI = 58–99 at selected mainstem locations, indicating Moderate Condition (Lowland Zone: Poor to Moderate; Slopes Zone: Moderate; Upland Zone: Good). • High-flow magnitudes were Near Reference Condition in the Upland Zone, but reduced in the Coliban and by up to 60% downstream of Lake Eppalock. • Incidence and duration of low and zero flows showed Very Large Differences from Reference Condition in the Lowland and Slopes Zones, but were Near Reference Condition in the Upland Zone. • Flow variation was Near Reference Condition, except in the lower Campaspe where monthly variability was 63% of the Reference Condition value. • Seasonality of flows was Near Reference Condition at all sites above Lake Eppalock, but there was a Moderate to Very Large Difference from Reference Condition downstream. • Annual flow volume was near Reference Condition except in the middle and lower Coliban and the lower Campaspe, where mean and median volumes were 55–60% and 21–45% of Reference Condition. Fish Theme • Condition Index SR–FI = 5 (CL 2–17), indicating Extremely Poor Condition (equal lowest for all Valleys). Condition was similar among Zones (all Zones: Extremely Poor). • Sixteen species caught, including eight alien species. • Predicted native species were reduced in the Lowland (76%), Slopes (78%) and Upland Zones (75%). • Mean abundance 65 fish per site, mainly alien species (79%). • Biomass dominated by alien species (93%). Macroinvertebrate Theme • Condition Index SR–MI = 41 (0CL 36–45), indicating Poor Condition (Lowland Zone: Poor; Slopes and Upland Zones: Very Poor). • Low to very low proportions of expected families in all Zones, particularly the Slopes and Upland Zones. • Loss of disturbance-sensitive families, especially in the Slopes Zone. 97
Table CAM.7: Campaspe Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland
Poor to Hydrology Condition Moderate Moderate Good Rating Moderate 5 (2–17) 2 (0–8) 1 (0–24) 17 (6–24) Fish Index Extremely Extremely Extremely Extremely Rating Poor Poor Poor Poor
Macroinvertebrate Index 41 (36–45) 48 (39–53) 33 (25–42) 39 (28–47) Rating Poor Poor Very Poor Very Poor
Ecosystem Health Very Very Extremely Extremely Rating Poor Poor Poor Poor
98
5.6 Castlereagh Valley
5.6.1 Hydrology
Figure CAS.1: Castlereagh Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Castlereagh Valley indicated Good Condition. This applied in all Zones.
The Castlereagh River rises in the Great Dividing Range southwest of Coonabarabran and flows northwest to the Barwon and lower Macquarie rivers via a network of channels. The Castlereagh has several foothill tributaries, and there are also tributaries running parallel to the channel in the Lowland Zone, some joining the river within 50 km of the Valley terminus. There are no major instream storages or irrigation developments. Only three modelled sites were available, and the furthest downstream, at Coonamble, is over 100 km from the terminus and upstream of several tributary inflows. Figure CAS.1 shows the value of the Hydrology Index, SR–HI, and Table CAS.1 shows the index and indicator values for all three hydrology sites in the Castlereagh Valley. These sites provide 99 examples of hydrological conditions in the main streams across the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at the three sites assessed was Near Reference (SR–HI = 100). Data were available for only three sites on the Castlereagh mainstem, and not for tributaries. All indicators showed Near Reference Condition at all sites. Assuming that there is little or no modification to flow downstream of Site 1, or in tributaries that join the Castlereagh below that site, the regime generally is little different from Reference Condition.
Table CAS.1: Castlereagh Valley: SR Hydrology Index and indicators. Sites are shown in Figure CAS.1.
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Castlereagh at Coonamble Lowland 100 100 100 100 100 100 2 Castlereagh at Gilgandra Slopes 100 100 100 100 100 100 3 Castlereagh at Mendooran Slopes 100 100 100 100 100 100
100
5.6.2 Fish
100 Good 80 Moderate 60 Poor 40 35 Very Poor 20 14 18 5 Extremely Poor 0 Valley lowland Slopes upland
Figure CAS.2: Castlereagh Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 101
The Castlereagh Valley fish community was in Extremely Poor Condition throughout. The community had lost most of its native species and was dominated by alien fish.
Communities at 18 sites across three altitudinal Zones of the Castlereagh Valley were surveyed in March–April 2007, yielding 5,112 fish. Only four sites were available in the Lowland Zone because of drought. Analyses showed Extreme (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 14 (CL 0–23). • Expectedness showed an Extreme (+) Difference from Reference Condition. • Nativeness showed a Very Large (–) Difference from Reference Condition. • Two-thirds or more of the predicted native fish species were missing. • Only 37% of fish abundance and 19% of biomass were contributed by native species. Figure CAS.2 shows sampling sites, Zones and corresponding SR–FI values, and Table CAS.2 shows Index values, Indicators, Metrics and derived variables. The Castlereagh Valley recorded the equal fifth-lowest SR–FI score in the Basin, Condition uniform within and among Zones, except for sites in the Upland Zone, which varied sharply in Nativeness. Some sites had abundant native fish and few alien species; others had the converse. The Valley showed an Extreme (+) Difference from Reference Condition (RC–F) (Lowland Zone: Extreme (+) Difference, Slopes Zone: Extreme Difference, Upland Zone: Very Large (±) Difference). Only 33%, 23% and 25% of predicted RC–F species were recorded from the Lowland, Slopes, and Upland Zones, respectively, and these Zones had two, three and three alien species, respectively. No fish were caught at two sites in each of the Lowland and Upland Zones, and no native fish were caught at six sites in the Valley. Abundance in the Lowland Zone was very low (37 fish per site). Table CAS.3 shows that a single Spangled perch and two Golden perch were caught in the Lowland Zone, where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, are listed. Notable among them are Freshwater catfish, Murray cod, River blackfish and Silver perch, as well as several less well- known small species. Many Abnormalities (8%) were recorded at Lowland Zone sites. None of the expected Intolerant species were caught. There were few Mega-carnivore species, especially in the Upland Zone, where only one Freshwater catfish was caught. 102
Table CAS.2: Castlereagh Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland
Fish Index 14 (0–23) 18 (1–34) 5 (2–12) 35 (0–41) Expectedness Indicator 15 (10–27) 17 (15–38) 11 (11–11) 20 (7–20) Nativeness Indicator 38 (6–34) 41 (0–41) 25 (19–37) 66 (0–84) Metric Total species 9 6 6 6 Native species 6 4 3 3 Predicted RC–F species count 14 12 13 12 Alien species 3 2 3 3 Caught/Predicted native species (%) 43 33 23 25 Numbers of fish Mean fish per site 284 38 242 467 Native individuals (%) 37 70 57 26 Fish biomass Biomass/site all species (g) 4,037 6,606 6,162 443 Mean native biomass/fish (g) 7 77 6 0 Mean alien biomass/fish (g) 18 396 52 1 Biomass native (%) 19 31 13 10
103
Table CAS.3: Castlereagh Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Zone Total Native species Lowland Slopes Upland
Australian smelt 0 14 15 29 Bony herring 67 0 0 67 Carp gudgeons 36 952 824 1,812 Freshwater catfish 0 0 1 1 Golden perch 2 4 0 6 Mountain galaxias 0 0 Murray cod 0 0 0 0 Murray–Darling rainbowfish 0 0 0 0 Olive perchlet 0 0 0 River blackfish 0 0 0 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 Spangled perch 1 0 1 Un-specked hardyhead 0 0 0 0
Alien species
Carp 30 28 2 60 Eastern gambusia 643 2,421 3,064 Goldfish 16 51 5 72
104
5.6.3 Macroinvertebrates
100 Good 80 Moderate 60 49 Poor 40 41 37 34 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure CAS.3: Castlereagh Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 105
The Castlereagh macroinvertebrate community was in Poor Condition. The Lowland Zone community was in Poor Condition, and the Slopes and Upland Zone communities were in Very Poor Condition. Communities at most sites were impoverished and lacked most disturbance-sensitive families.
Owing to dry conditions, only 18 sites were surveyed across three Zones of the Castlereagh Valley in March 2006, yielding 4,291 macroinvertebrates and 53 families (39% of Basin families). The low proportion (51%) of sites sampled means that the assessment for this Valley should be treated with caution. Biased site selection may have affected the Valley SR–MI score and Condition rating, and low numbers of sites will have increased the confidence interval for both Valley and Zone assessments. Analyses showed a Large (–) Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 41 (CL 36–52). • A moderate to low proportion of expected families (Filters OE = 25). • Much reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 81). SR–MI for the Castlereagh Valley was the equal third-lowest score of all Valleys (cf. Campaspe). The Lowland Zone community showed a Large Difference from Reference Condition (SR–MI = 49), and the Slopes and Upland Zones showed a Very Large Difference (SR–MI = 34, 37, respectively). There were wide confidence intervals for SR–MI in all Zones. Figure CAS.3 shows sampling sites, Zones and SR–MI values, and Table CAS.4 shows metrics and derived variables. Only 57% of expected families were recorded in the Valley, and family richness was less than Reference Condition at all but one site. Diversity was moderate to high (average 21 families per site), and least in the Lowland Zone (average 17 families per site). Most (82%) of the Valley fauna was in the Upland Zone (cf. 68–70% for the Lowland and Slopes Zones). Table CAS.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Only one site in the Valley had a high Filters OE score, and two of the 18 sites had a low Filters OE score. Filters SIGNAL OE scores were consistently low for the Slopes and Upland Zones, and with a high proportion (7 of 10) of sites in these Zones had a low Filters SIGNAL OE score. The faunas at most Slopes and Upland Zones were impoverished and missing most disturbance–sensitive families. Table CAS.6 shows ‘common’ and ‘rare’ families. The 14 common families included midge larvae (Chironominae, Tanypodinae), diving beetles (Dytiscidae), crustaceans (Ostracoda), backswimmers (Notonectidae) and other aquatic insects. The four rare families were caddisflies (Ecnomidae, Hydroptilidae), water striders (Gerridae) and blackfly larvae (Simuliidae). 106
Table CAS.4: Castlereagh Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 41 49 34 37 (36–52) (38–69) (28–60) (26–42) Metrics Filters OE 25 28 23 24 (22–32) (22–40) (19–39) (22–26) Filters SIGNAL OE 81 87 77 78 (78–87) (80–96) (74–86) (71–81) Families Families per site 21 17 23 23 minimum – maximum 12–33 12–26 16–33 14–31 Total families 53 35 38 45
Table CAS.5: Castlereagh Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 18 6 5 7
Filters OE High 1 1 Medium 15 5 4 6 Low 2 1 1 Filters SIGNAL OE High Medium 10 5 2 3 Low 8 1 3 4
107
Table CAS.6: Castlereagh Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 6 5 7 18 Number of families sampled 38 39 46 56 Percent of families in Basin 34.9 32.0 41.1 39.2 Percent of families in Valley 68 70 82 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Chironominae 100 100 100 100 Dytiscidae 100 100 100 100 Ostracoda 100 100 100 100 Notonectidae 100 80 100 94 Tanypodinae 100 80 100 94 Ceratopogonidae 67 100 100 89 Hydraenidae 100 80 86 89 Parastacidae 83 80 86 83 Tabanidae 83 60 29 56 Gomphidae 80 71 50 Libellulidae 17 60 71 50 Ephydridae 60 17 Richardsonianidae 17 6 Rare Ecnomidae 14 6 Gerridae 17 6 Hydroptilidae 20 6 Simuliidae 14 6
108
5.6.4 Ecosystem Health
The Castlereagh Valley river ecosystem was in Very Poor Health (Lowland and Upland Zones: Very Poor; Slopes Zone: Extremely Poor). Fish abundance and biomass were dominated by alien species and most expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. The flow regime showed little change from Reference Condition.
Summary Theme assessments are as follows (Table CAS.7): Hydrology Theme • Condition Index SR–HI = 100, indicating Good Condition. • The magnitude of high flows and mean and median annual volumes, the incidence and duration of low and zero flows, flow variation and seasonality of flows were all Near Reference Condition. Fish Theme • Condition Index SR–FI = 14 (CL 0–23), indicating Extremely Poor Condition and equal fifth-lowest score of all Valleys. The Lowland and Slopes Zones were in Extremely Poor Condition and the Upland Zone was in Very Poor Condition. • Predicted native species richness was reduced in the Lowland (67%), Slopes (77%) and Upland Zones (75%). • Mean abundance 284 fish per site, mainly alien species (63%). • Biomass dominated by alien species (81%). Macroinvertebrate Theme • Condition Index SR–MI = 41 (CL 36–52), indicating Poor Condition (Lowland Zone: Poor; Slopes, Upland Zones: Very Poor). • Moderate to low diversity and proportions of expected families in all Zones. • Moderate reduction of disturbance-sensitive families in the Slopes and Upland Zones. 109
Table CAS.7: Castlereagh Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley
Zone
Valley Lowland Slopes Upland
Hydrology Condition Good Good Good Good Rating
14 (0–23) 18 (1–34) 5 (2–12) 35 (0–41) Fish Index Extremely Extremely Extremely Very Rating Poor Poor Poor Poor
Macroinvertebrate Index 41 (36–52) 49 (38–69) 34 (28–60) 37 (26–42) Rating Poor Poor Very Poor Very Poor
Ecosystem Health Very Very Extremely Very Rating Poor Poor Poor Poor
110
5.7 Condamine Valley
5.7.1 Hydrology
Figure CON.1: Condamine Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores at selected sites on the Condamine, Balonne, Culgoa, Maranoa and Narran channels were 50–100, indicating Moderate to Good Condition (Lowland Zone: Moderate; Slopes Zone: Moderate to Good).
The Condamine Valley covers 136,500 km2, or about 13% of the Basin area, mostly in southern Queensland, and discharges either to the Barwon via the Culgoa and Bokhara rivers, or to terminal lakes at Narran via braided streams on the Lower Balonne Floodplain. The river changes name along its course. The Condamine rises on the western flank of the Great Dividing Range in the north-eastern Basin, flows north-west then west to Surat, where it becomes the Balonne River and flows south-westerly, breaking into distributary channels, the largest of these becoming the Culgoa River. More than 20 unregulated tributaries feed the Condamine-Balonne system upstream of St George. 111
Flows in the system are regulated by instream storages on the Condamine (Leslie Dam, 106 GL; Chinchilla Weir, 10 GL) and Beardmore Dam on the Balonne (including Buckinbah, Moolabah and Jack Taylor Weirs, total 93.5 GL). The capacities of private offstream storages, however, greatly exceed those of the instream storages. Only the Leslie Dam has a capacity higher than its average annual inflow (106 v. 30 GL). Figure CON.1 shows values of the Hydrology Index for five selected sites and Table CON.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Index scores showed Near Reference Condition at Sites 3 and 5 (SR–HI = 91, 100), a Moderate Difference from Reference Condition at Sites 2 and 4 (SR–HI = 60, 73) and a Large Difference at Site 1. The indicators show:
• High-Flow Events: Near Reference Condition at Site 5, Moderate Difference from Reference Condition at Site 3, Large Difference at Sites 2 and 4 and Very Large Difference at Site 1. High flows were reduced by 30–50% in the Condamine downstream of Warwick, and by 40–55% in Lowland Zone sites (Narran, Culgoa Rivers), but were Near Reference Condition in the Maranoa River. • Low- and Zero-Flow Events: Near Reference Condition at most sites but altered in the Condamine Slopes Zone where Site 4 showed a Large Difference, low flows being more frequent. • Variability: Sites 3 and 5, were Near Reference Condition and other sites showed a Moderate Difference. • Seasonality: All selected sites were Near Reference Condition, with only moderate shifts in some other sites in the middle Condamine, lower Balonne and some tributaries (values not shown). • Gross Volume: Near Reference Condition at Site 5 to Extremely Large Difference from Reference Condition at Site 1 (lower Culgoa at Brenda). Annual flow volumes throughout the Valley were reduced by between 20–60% of mean values compared to Reference Condition, with the exception of the Maranoa River. Median annual volumes in the Condamine-Balonne channel were reduced by 40–95%. The Condamine headwaters (Site 5) were unmodified and the Maranoa River was in Good Condition throughout. The remaining sites were affected by flow regulation and high-flow harvesting, partly offset by unregulated tributary flows. Lowland Zone sites on the Narran and Culgoa rivers have their high-flow magnitudes halved. In general, the Condamine Valley flow regime was characterised by reduced high flows and annual volumes, and minor to moderate changes in variability and seasonality. 112
Table CON.1: Condamine Valley: SR Hydrology Index and indicators. Sites are shown in Figure CON.1. US: upstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Culgoa at Brenda Lowland 50 30 64 61 88 15 2 Narran River at Narran Park Lowland 72 40 87 69 90 64 3 Balonne River at Weribone Slopes 91 75 91 88 93 57 4 Condamine at Chinchilla Slopes 60 56 51 72 86 32 5 Condamine US Warwick Slopes 100 100 100 99 100 100
113
5.7.2 Fish
100 Good 80 Moderate 60 63 62 64 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure CON.2: Condamine Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 114
The Condamine Valley fish community was in Moderate Condition. Most fish were native species, but these were only half the total biomass. Alien fish were widespread.
Nineteen sites in the Condamine Valley (11 in the Lowland Zone and eight in the Slopes Zone) were surveyed in March, April and May 2007, yielding 3501 fish. Analyses showed a Moderate (–) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 63 (CL 47–71). • Expectedness showed a Large (–) Difference from Reference Condition. • Nativeness showed a Moderate (±) Difference from Reference Condition. • Ten (56%) of 18 predicted (RC–F) native species were recorded. • Native fish were most (86%) of the total catch but less than half (44%) of total biomass. Figure CON.2 shows sampling sites, Zones and corresponding SR–FI values, and Table CON.2 shows Index values, Indicators, Metrics and derived variables. Seven native species were found in the Lowland Zone and 10 in the Slopes. Three alien species were found in each Zone. The Valley Fish Index (SR–FI = 63) was the second highest score for the Basin. The two Zones produced similar Index and Indicator scores, and there was little difference between Zones in the values of Metrics and variables. Variability between sites also was moderate in both Zones. The Condamine Valley showed a Moderate (–) Difference from Reference Condition (RC–F) (Slopes Zone: Moderate (–), Lowland Zone: Moderate (–)). Of the predicted species, 50% and 56% were recorded from the Lowland and Slopes Zones, respectively. The native proportion of total biomass and the numbers of native individuals in the catch were nearly identical in the two Zones. Catches were abundant, averaging 184 fish per site overall, with most in the Slopes Zone (288 per site). Bony herring were numerous and Carp gudgeons, Australian smelt, Golden perch, Murray-Darling rainbowfish and Spangled perch also were common. Three alien species, Eastern gambusia, Goldfish and Carp, were captured frequently; there were 1-3 alien species at all but four of the 19 sites. Table CON.3 shows that only a single Murray cod was found in the Slopes Zone, where they were predicted to be common. Species not caught, but predicted to occur rarely or occasionally under Reference Condition, are also listed. Notable among them are Freshwater catfish, River blackfish, Rendahl’s tandan and Silver perch, with several small, less well-known species. No Intolerant species were caught. Few visible Abnormalities were recorded (<2%); those few were mainly at Lowland sites (3.3%). Mega-carnivores were common in both Zones.
115
Table CON.2: Condamine Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes
Fish Index 63 (47–71) 62 (39–67) 64 (43–80) Expectedness Indicator 50 (36–56) 46 (31–60) 53 (39–62) Nativeness Indicator 73 (45–92) 76 (45–95) 69 (33–97) Metric Total species 13 10 13 Native species 10 7 10 Predicted RC–F species count 18 14 18 Alien species 3 3 3 Caught/Predicted native species (%) 56 50 56 Numbers of fish Mean fish per site 184 109 288 Native individuals (%) 86 86 86 Fish biomass Biomass/site all species (g) 4,369 3,751 5,220 Mean native biomass/fish (g) 12 18 9 Mean alien biomass/fish (g) 95 140 72 Biomass native (%) 44 44 45
116
Table CON.3: Condamine Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks Zone Native species Total Lowland Slopes Australian smelt 52 43 95 Bony herring 853 1,663 2,516 Carp gudgeons 20 148 168 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 0 0 Freshwater catfish 0 1 1 Golden perch 46 20 66 Hyrtl's tandan 0 0 0 Mountain galaxias 0 0 Murray cod 3 1 4 Murray–Darling rainbowfish 41 21 62 Olive perchlet 0 1 1 Rendahl’s tandan 0 0 0 River blackfish 0 0 Silver perch 0 0 0 Southern purple-spotted gudgeon 0 0 0 Spangled perch 15 80 95 Un-specked hardyhead 0 9 9
Alien species
Carp 33 30 63 Eastern gambusia 126 173 299 Goldfish 6 116 122
117
5.7.3 Macroinvertebrates
100 Good 80 Moderate 60 63 55 53 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure CON.3: Condamine Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 118
The Condamine Valley macroinvertebrate community was in Poor Condition, with Lowland and Slopes Zone communities in Moderate and Poor Condition, respectively. Most sites had impoverished faunas, lacking many disturbance-sensitive families.
Thirty five sites were surveyed across two Zones of the Condamine Valley in June 2006, yielding 5,651 macroinvertebrates and 55 families (39% of Basin families). Analyses showed a Large (+) Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 55 (CL 51–64). • Moderate proportion of expected families (Filters OE = 31). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 92). SR–MI for the Condamine Valley was the eighth highest score for all Valleys (cf. Gwydir). The Lowland Zone community showed a Moderate (–) Difference from Reference Condition (SR–MI = 63), and the Slopes Zone showed a Large Difference (SR–MI = 53). Wide confidence intervals for SR–MI in both Zones (19 points) indicate substantial variation in condition among sites. Figure CON.3 shows sampling sites, Zones and SR–MI values, and Table CON.4 shows metrics and derived variables. Only 70% of expected macroinvertebrate families were recorded in the Valley, and family richness was below Reference Condition at 31 of 35 sites. Diversity was moderate to low (average 18 families per site). Most (86–91%) of the Valley fauna was found in both Zones. Table CON.5 shows that Expected (Filters OE) scores indicate substantial loss of expected families. Only four sites had a high Filters OE score, and three sites had a low Filters OE score. Filters SIGNAL OE scores were consistently low for both Zones, and many sites (33) had a reduced score. Most sites in both Zones had impoverished communities, without many disturbance-sensitive families. Table CON.6 shows ‘common’ and ‘rare’ families. The 10 common families included midges (Chironominae, Ceratopogonidae), damselflies (Libellulidae), crustaceans (Ostracoda) and aquatic beetles (Hydraenidae, Hydrophilidae). The 16 rare families included a variety of crustaceans, molluscs and aquatic insects. 119
Table CON.4: Condamine Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Index SR–MI 55 63 53 (51–64) (53–72) (41–62) Metrics Filters OE 31 35 31 (28–36) (30–39) (23–36) Filters SIGNAL OE 92 97 89 (90–95) (91–97) (88–94) Families Families per site 18 18 19 minimum – maximum 8–27 8–25 10–27 Total families 55 50 48
Table CON.5: Condamine Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes
Number of sites 35 19 16
Filters OE High 4 3 1 Medium 28 16 12 Low 3 3 Filters SIGNAL OE High 2 2 Medium 33 19 14 Low
120
Table CON.6: Condamine Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 19 16 35 Number of families sampled 51 48 56 Percent of families in Basin 46.8 39.3 39.2 Percent of families in Valley 91 86 100
Percent of sites by Zone Lowland Slopes VALLEY
Common Chironominae 100 100 100 Corixidae 100 100 100 Ostracoda 100 88 94 Ceratopogonidae 100 69 86 Hydraenidae 95 69 83 Hydrophilidae 79 81 80 Culicidae 47 69 57 Libellulidae 58 38 49 Noteridae 21 56 37 Pleidae 16 50 31 Rare Veliidae 21 44 31 Orthocladiinae 26 19 23 Physidae 5 25 14 Gerridae 11 13 11 Gyrinidae 13 6 Hydrometridae 5 6 6 Leptophlebiidae 5 6 6 Conchostraca 5 3 Elmidae 5 3 Hebridae 5 3 Heteroceridae 5 3 Hydroptilidae 5 3 Protoneuridae 5 3 Pyralidae 5 3 Richardsonianidae 6 3 Scirtidae 6 3
121
5.7.4 Ecosystem Health
The Condamine Valley river ecosystem was in Moderate Health (Lowland and Slopes Zones: Moderate). Fish abundance was dominated by native species, but biomass was dominated by alien species, and several expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. High-flow and annual volumes were reduced, and there were minor changes to flow variability and seasonality.
Summary Theme assessments are as follows (Table CON.7): Hydrology Theme • Condition Index SR–HI = 60–100 at selected locations on the Condamine, Balonne, Culgoa and Narran, indicating Moderate to Good Condition (Lowland Zone: Moderate; Slopes Zone: Moderate to Good). The tributary Maranoa River was in Good Condition. • High-flow magnitudes were Near Reference Condition in the upper Condamine, but 40– 55% of Reference Condition at Lowland Zone sites (Narran, Culgoa Rivers). • Incidence and duration of low and zero flows generally were Near Reference Condition in most streams, but substantially altered in the middle Condamine. • Flow variability generally was Near Reference Condition. • Seasonality generally was Near Reference Condition, with moderate shifts in the middle Condamine, lower Balonne and some tributaries. • Mean annual flow volumes were reduced throughout by 20–60% compared to Reference Condition. Median annual flows in Condamine-Balonne mainstem reaches were reduced by 40–95%. Fish Theme • Condition Index SR–FI = 63 (CL 47–71), indicating Moderate Condition, the second highest of all Valleys. Condition was similar between Zones (both Zones: Moderate). • Thirteen species caught, including three alien species. • Predicted native species reduced in the Lowland (50%) and Slopes Zones (44%). • Mean abundance 184 fish per site, mainly native species (86%). • Biomass mainly alien species (56%). Macroinvertebrate Theme • Condition Index SR–MI = 55 (CL 51–64), indicating Poor Condition (Lowland Zone: Moderate; Slopes Zone: Poor). • Moderate to low diversity and proportions expected families in both Zones. • Moderate reduction of disturbance-sensitive families in both Zones. 122
Table CON.7: Condamine Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes
Moderate Moderate Hydrology Condition Moderate Rating to Good to Good Fish Index 63 (47–71) 62 (39–67) 64 (43–80) Rating Moderate Moderate Moderate
Macroinvertebrate Index 55 (51–64) 63 (53–72) 53 (41–62) Rating Poor Moderate Poor
Ecosystem Health Moderate Moderate Moderate Rating
123
5.8 Darling Valley
5.8.1 Hydrology
Figure DAR.1: Darling Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for selected sites along the Darling mainstem were 47– 74, indicating Poor Condition(Lower Zone: Poor; Middle and Upper Zones Moderate).
The Darling River and its tributaries drain the northernmost part of the Basin. Most of the tributaries rise on the flanks of the Great Dividing Range in south-eastern Queensland and north- eastern New South Wales. In addition, the Paroo and Warrego Rivers drain the arid north-western region. The main contributors are the Border Rivers (35 percent of long-term annual discharge), Namoi (25 percent), Condamine (20 percent), Gwydir (10 percent), Castlereagh and Macquarie (5 percent) and Paroo and Warrego Valleys (5 percent) (Thoms et al. 2004). All but the Macquarie are ‘summer flow’ rivers, in that much of their annual discharge originates from summer rainfall. The Paroo and Warrego are highly episodic; their flows usually do not reach the Darling. 124
There is little diversion from the Paroo or Warrego, and their current flow regimes are considered equivalent to Reference Condition. There are major irrigation storages on the Condamine, Border Rivers, Gwydir, Namoi, and Macquarie; the major (volumetric) tributaries of the Darling. There are no instream storages on the Darling, other than low-level weirs to provide domestic and stock supply during zero-flow periods. There are 15 such weirs on the Darling upstream of Menindee, ‘ponding’ some 640 km of the river (Thoms et al. 1996). Most diversions take the form of opportunistic harvesting of high flows, and licences preclude pumping at other times. The major irrigated crop is cotton, with citrus and grapes in the lower reaches. A series of annexed deflation lakes at Menindee regulates flow to the lower river, including the Great Anabranch. Figure DAR.1 shows the value of the Hydrology Index, SR–HI, for all sites and Table DAR.1 shows the index and indicator values for five sites along the Valley. Even the uppermost reaches of the Darling (Site 5) show a Moderate Difference from Reference Condition (SR–HI = 73). There is a gradual, slight decline in the index until downstream of Menindee (Site 1), where SR–HI is 47 (Large Difference from Reference Condition). The indicators show:
• High-Flow Events: Reduced throughout the Valley, particularly in the lower reaches, mirroring systematic harvesting. • Low- and Zero-Flow Events: Largely preserved. • Variability: Reduced, probably reflecting suppression of high flows. • Seasonality: The Darling does not have an inherently strong seasonal flow pattern, and the suppression of high flows may have obscured an already weak seasonal pattern. Diversions are opportunistic rather than seasonal. • Gross Volume: Low values, particularly in the lower reaches, reflect the bulk removal of water for irrigation. At all five sites, indicators for Gross Volume of annual flow (GV) and High-Flow Events (HFE) consistently show the greatest differences from Reference Condition. This reflects the volume of water diverted from the system and the effect of differentially harvesting high flows. Low- and zero-flow events are little changed under current management.
Table DAR.1: Darling Valley: SR Hydrology Index and indicators. Sites are shown in Figure DAR.1
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Burtundy Lower 47 12 95 56 47 21 2 Menindee Middle 69 39 93 70 83 36 3 Wilcannia Middle 71 42 98 70 86 36 4 Bourke Upper 74 47 99 74 83 43 5 Barwon River at Walgett Upper 73 45 86 77 84 47
125
5.8.2 Fish
100 Good 80 Moderate 63 60 59 57 55 Poor 40 Very Poor 20 Extremely Poor 0 Valley lower middle upper
Figure DAR.2: Darling Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 126
The Darling Valley fish community was in Poor Condition. Over half the predicted native species were not found, although the intrusion of alien species was moderate compared to other Valleys and native fish were often abundant.
Fish in the Darling Valley were surveyed in February–March 2005, including 21 sites in three Zones, yielding 3,156 fish. Analyses indicated a Large (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 59 (CL 56–68). • Only half the predicted native species were recorded. • Nativeness showed a Moderate (+) Difference from Reference Condition. Figure DAR.2 shows sampling sites, Zones and corresponding SR–FI values, and Table DAR.2 shows Index values, Indicators, Metrics and derived variables. The Darling had the equal fourth- highest Fish Index score (SR–FI = 59) among all Valleys (cf. Namoi). Seven native species and three alien species occurred in each of the three Valley Zones. In the Darling, ‘Lower’, ‘Middle’, and ‘Upper’ Zones were distinguished to ensure that sampling sites were distributed throughout the Valley. These Zones do not represent marked altitudinal differences, although there are north-south differences in seasonal temperatures and rainfall patterns, as well as species representation (for example, Hyrtl’s tandan and Spangled perch occur in northern areas, and Redfin perch and Tench occur in southerly areas). The Zones also experience some differences related to water management, with suppressed flow peaks and extended low-flow periods in the Upper and Middle Zones, several weirs in the Middle Zone and regulated flow releases from the Menindee Lakes in the Lower Zone. Despite these differences, the Darling Valley had the equal fourth-highest Fish Index score among all Valleys. Index scores in the Valley were relatively even, although higher in the Middle Zone where Nativeness was highest and most variable. More uniform distributions of dominant native and alien fish were apparent in the Lower and Upper Zones. The Valley community showed a Large (+) Difference from Reference Condition (Lower Zone: Large (+) Difference, Middle Zone: Moderate (–) Difference, Upper Zone: Large (+) Difference). Table DAR.3 shows that the numbers of native species in all three Zones were less than half of those predicted under Reference Condition (47% in each Zone, with 50% of predicted species across the Valley). Native species richness was quite different from Reference Condition. Species not caught, but predicted to be common under Reference Condition, included Un-specked hardyhead, Murray–Darling rainbowfish and Freshwater catfish. Other species not caught, but predicted to be rare or moderately rare in one or more Zones under Reference Condition, included Silver perch, Southern purple-spotted gudgeon and Freshwater catfish. The total abundance of fish in the Upper Zone (average 75 fish per site) was about half that in the Lower Zone (146) and one-third that in the Middle Zone (230), but this was offset by the larger sizes of individuals in the Upper Zone. Native fish were 47% of total biomass in the Lower Zone, and more in the Middle (79%) and Upper Zone (65%). The Middle Zone yielded most fish per site and the highest proportion of total biomass, and also the highest percentage of individual native fish (95%). The total biomass of native fish remained consistent (9–11 kg per site) across Zones. The mean weight of individual native fish varied between Zones, with those in the Upper Zone being larger (average 182 g per fish). Alien fish were larger (up to 504 g per fish) in the Lower Zone. 127
Among the native species, Bony herring, Carp gudgeons and Golden perch were conspicuous. Carp and Goldfish dominated the alien species. Across the Valley, fewer than 4% of fish showed Abnormalities in all but the Upper Zone, where there were 10% Abnormalities. No Intolerant species were recorded. Macro- and Mega-carnivore species were common in all Zones.
Table DAR.2: Darling Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lower Middle Upper
Fish Index 59 (56–68) 57 (51–67) 63 (55–68) 55 (48–70) Expectedness Indicator 48 (45–50) 48 (48–53) 48 (42–48) 47 (41–52)
Nativeness Indicator 69 (62–86) 65 (51–85) 76 (60–95) 61 (48–87) Metrics Total species 12 10 10 10 Native (RC–F) species 9 7 7 7 Predicted RC–F species count 18 15 15 15 Alien species 3 3 3 3 Caught/Predicted native species (%) 50 47 47 47 Numbers of fish Mean fish per site all species 150 146 230 75 Native individuals (%) 89 86 95 77 Fish biomass Total biomass/site all species (g) 16,803 20,115 14,259 16,034 Mean native biomass/fish (g) 78 76 52 182 Mean alien biomass/fish (g) 382 504 249 323 Biomass native (%) 62 47 79 65
128
Table DAR.3: Darling Valley: numbers of native fish by Zone. Predicted species (RC–F list) are shown as numbers; species not predicted are shown as blanks
Native species Zone Total Lower Middle Upper
Australian smelt 29 77 2 108 Bony herring 516 1375 284 2,175 Carp gudgeons 289 42 20 351 Desert rainbowfish 0 0 Flat-headed gudgeon 3 0 3 Freshwater catfish 0 0 0 0 Golden perch 24 15 67 106 Hyrtl's tandan 0 0 0 Murray cod 13 4 21 38 Murray hardyhead 0 0 Murray–Darling rainbowfish 1 0 6 7 Olive perchlet 0 0 0 0 Rendahl’s tandan 0 0 Short-headed lamprey 0 0 0 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 Spangled perch 0 8 4 12 Un-specked hardyhead 0 4 0 4
Alien species
Carp 98 48 104 250 Eastern gambusia 2 23 11 36 Goldfish 48 13 5 66 129
5.8.3 Macroinvertebrates
100 Good 80 83 Moderate 60 52 47 50 Poor 40 Very Poor 20 Extremely Poor 0 Valley lower middle upper
Figure DAR.3: Darling Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 130
The Darling Valley macroinvertebrate community was in Poor Condition. The Lower and Middle Zone communities were in Poor Condition, and the Upper Zone community was in Moderate to Good Condition. The communities at most sites were impoverished and lacked many disturbance–sensitive families.
Thirty eight sites were surveyed across three Zones of the Darling Valley in April 2005, yielding 4,425 macroinvertebrates in 49 families (36% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 52 (CL 48–56). • A moderate to low proportion of expected families (Filters OE = 29). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 91). SR–MI for the Darling Valley was in the mid-range of scores for all Valleys (cf. Namoi, Lachlan, Namoi, Broken, Loddon). The Lower and Middle Zone communities each showed a Large Difference from Reference Condition (SR–MI = 47, 50 respectively), and the Upper Zone was in Near Reference Condition (–) (SR–MI = 83). In the Upper Zone, a wide confidence interval for SR–MI (32 points) indicates considerable variation in condition among sites. Figure DAR.3 shows sampling sites, Zones and SR–MI values, and Table DAR.4 shows metrics and derived variables. Eighty six percent of expected families were recorded, although richness was less than Reference Condition at 33 of the 38 sites. Diversity was low to moderate (average 16 families per site), and highest in the Upper Zone (average 21 families per site). Most (88%) of the Valley fauna was in the Middle Zone (cf. 71-73% for Lower and Upper Zones). Table DAR.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Five sites had a high Filters OE score, and three sites had a low Filters OE score. Filters SIGNAL OE scores were reduced for all Zones, but only one site had a low score. Most sites in all three Zones had impoverished communities, lacking most disturbance-sensitive families. Table DAR.6 shows ‘common’ and ‘rare’ families. Nine common families included prawns, crayfish (Palaemonidae, Parastacidae), mayflies (Caenidae), midges (Chironominae) and water boatmen (Corixidae). The common prawn Macrobrachium australiense, is part of the diet of many fish, and is often used by fishermen as bait. The 18 rare families included crustaceans (Ostracoda), beetles (Hydrophilidae, Dytiscidae, Limnichidae), little basket shells (Corbiculidae), dragonflies and damselflies (Gomphidae, Aeshnidae, Isostictidae) and other aquatic insects. 131
Table DAR.4: Darling Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lower Middle Upper
Index SR–MI 52 47 50 83 (48–56) (37–53) (45–55) (57–89) Metrics Filters OE 29 26 28 43 (27–32) (22–29) (25–31) (31–45) Filters SIGNAL OE 91 91 90 97 (89–95) (85–97) (89–96) (94–106) Families Families per site 16 15 16 21 minimum – maximum 9–26 9–22 10–22 15–26 Total families 49 36 43 36
Table DAR.5: Darling Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lower Middle Upper
Number of sites 38 13 20 5
Filters OE High 5 2 3 Medium 30 11 17 2 Low 3 2 1 Filters SIGNAL OE High 2 1 1 Medium 35 13 18 4 Low 1 1
132
Table DAR.6: Darling Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 13 20 5 38 Number of families sampled 37 45 36 51 Percent of families in Basin 33.9 41.3 33.0 35.7 Percent of families in Valley 73 88 71 100
Percent of sites by Zone Lower Middle Upper VALLEY
Common Chironominae 100 100 100 100 Corixidae 100 100 100 100 Palaemonidae 100 100 100 100 Corallanidae 100 95 100 97 Caenidae 77 85 100 84 Gerridae 62 80 100 76 Parastacidae 69 75 80 74 Ecnomidae 23 65 40 47 Mesoveliidae 62 10 80 37 Rare Tanypodinae 31 65 60 53 Dytiscidae 15 65 60 47 Hydrophilidae 15 50 100 45 Leptoceridae 31 20 80 32 Oligochaeta 23 40 20 32 Ostracoda 46 10 21 Acarina 15 5 8 Gomphidae 15 8 Aeshnidae 8 5 5 Limnichidae 10 5 Corbiculidae 5 3 Ephydridae 5 3 Hebridae 20 3 Hirudinea 5 3 Isostictidae 20 3 Naucoridae 8 3 Planorbidae 8 3 Pleidae 20 3
133
5.8.4 Ecosystem Health
The Darling Valley river ecosystem was in Poor Health (Lower Zone: Poor; Middle Zone: Poor; Upper Zone: Moderate). The diversity and biomass of fish were dominated by native species, although many expected species were absent. Many expected and disturbance-sensitive macroinvertebrate families were absent. The flow regime had fewer high flows, and reduced annual volumes and variability, but showed little change to low and zero flows and to seasonality.
Summary Theme assessments are as follows (Table DAR.7): Hydrology Theme • Condition Index SR–HI = 47–74 at selected mainstem locations, indicating Poor Condition (Middle and Upper Zones: Moderate; Lower Zone: Poor). • High-flow magnitudes were reduced, particularly in the Lower Zone, by 30–88%. • Incidence of low flows and duration of zero flows were Near Reference Condition. No change in the number of zero flow days but low-flow magnitudes reduced by 17–30% at all but one site. • Flow variability reduced by 20-50%, particularly in the Lower Zone. • Seasonality of flows naturally weak and generally Near Reference Condition. • Mean and median annual flow volumes generally reduced by 33–55% and 60–90%, respectively, particularly in the Lower Zone. Fish Theme • Condition Index SR–FI = 59 (CL 56–68), indicating Poor Condition (fourth highest among Valleys). Condition varied little across Zones (Lower Zone: Poor; Middle Zone: Moderate; Upper Zone: Poor). • Twelve species caught, including three alien species. • Predicted native species reduced by more than half in all Zones. • Mean abundance 150 fish per site, mainly native species (89%). • Biomass dominated by native species in Middle (79%) and Upper Zones (65%) but not in Lower Zone (<50%). Macroinvertebrate Theme • Condition Index SR–MI = 52 (CL 48–56), indicating Poor Condition (Lower, Middle Zones: Poor; Upper Zone: Good). • Low to moderate diversity; low proportions of expected families except in the Upper Zone. • Loss of disturbance-sensitive families at most sites, except in the Upper Zone. 134
Table DAR.7: Darling Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lower Middle Upper
Hydrology Condition Poor Poor Moderate Moderate Rating
Fish Index 59 (56–68) 57 (51–67) 63 (55–68) 55 (48–70) Rating Poor Poor Moderate Poor
Macroinvertebrate Index 52 (48–56) 47 (37–53) 50 (45–55) 83 (57–89) Rating Poor Poor Poor Good
Ecosystem Health Poor Poor Poor Moderate Rating
135
5.9 Goulburn Valley
5.9.1 Hydrology
Figure GOU.1: Goulburn Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Goulburn Valley were 34–100, indicating Poor Condition (Lowland and Slopes Zones: Very Poor to Poor; Upland Zone: Good).
The Goulburn River rises in the Great Dividing Range, in the angle where the axis changes from a north-south to east-west orientation, and joins the Murray upstream of Echuca. Headwater streams join the Goulburn at the point now occupied by Lake Eildon, and in the upper three-quarters of its length, upstream of Shepparton. There are two instream storages, Lake Eildon (3334 GL) and Goulburn Reservoir (25.5 GL), and the latter, impounded by Goulburn Weir, is connected to an offstream storage, Waranga Basin (432 GL). Water from here is transferred to the Loddon or Campaspe valleys. Another offstream storage is Greens Lake (28 GL). The Goulburn River is intensively regulated and supports extensive irrigation areas (>150,000 ha). 136
Figure GOU.1 shows values of the Hydrology Index, SR–HI, for five selected sites and Table GOU.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). The Goulburn varies from Near Reference Condition (SR–HI = 100) upstream of Lake Eildon to a Very Large Difference from Reference Condition in downstream areas (SR–HI = 34). The indicators show:
• High-Flow Events: From Moderate to Very Large Differences from Reference Condition in the Goulburn River, where HFE was 40% lower downstream of Lake Eildon and 60% lower downstream of Goulburn Weir. Near Reference Condition in tributaries and the Goulburn upstream of Lake Eildon. • Low- and Zero-Flow Events: From Moderate to Extreme Differences from Reference Condition in the Eildon River. Low flows reduced by 65–99% downstream of Lake Eildon, but with no change in the numbers of zero flow days. Low-flow frequency increased by more than 99% downstream of Goulburn Weir, with a 60% increase in the number of zero flow days. Moderate to Very Large Differences in Lowland Zone tributaries. Near Reference Condition in Slopes Zone tributaries and the Goulburn upstream of Lake Eildon. • Variability: Large Differences from Reference Condition at all sites downstream of Lake Eildon (40% reduction). All other tributary and Goulburn River sites were Near Reference Condition. • Seasonality: Very Large Difference from Reference Condition below Lake Eildon, tending to Large to Moderate Differences downstream. Elsewhere, mainly Near Reference Condition. • Gross Volume: Annual flow volumes were Near Reference Condition upstream of the main diversions, declining downstream to Moderate and Extreme Differences. Mean annual volumes in the Goulburn downstream of Lake Eildon were unchanged, but median volumes were reduced by 45–50% (see Variability). Mean and median volumes in the Goulburn below Goulburn Weir were reduced by 60 and 90%, respectively. Several Lowland Zone tributaries showed reductions of 20-30% in mean annual discharge and 45– 100% in median annual discharge. Most Slopes Zone tributaries and the Goulburn upstream of Lake Eildon showed reductions in mean and median volumes of 1–30%. Values of GV were Near Reference Condition at Sites 4–5, upstream of the main diversions. The indicators reflect regulation through the operation of storages at Lake Eildon and Goulburn Weir, and the removal of water for irrigation and inter-valley transfers. The seasonal pattern of flow in ‘winter-spring rainfall’ rivers tends to be reversed in rivers regulated for irrigation, but this is partly offset by downstream diversions and inflows from unregulated tributaries. Indicators sensitive to the volume of flow tend to decline with distance downstream. In general, the Goulburn Valley flow regime was characterised by substantial changes in mean and median annual volumes and the magnitude and incidence of low flow and high flow events, with changes becoming greater downstream. 137
Table GOU.1: Goulburn Valley: SR Hydrology Index and indicators. Sites are shown in Figure GOU.1. US: upstream; DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Goulburn River outlet Lowland 35 40 0 61 71 20 Goulburn River US Seven Lowland 2 Creeks 34 40 0 60 65 18 Goulburn River US Goulburn Lowland 3 Weir 54 57 60 58 44 76 4 Goulburn River DS Yea River Slopes 56 63 71 58 20 80 Goulburn River US Lake Upland 5 Eildon 100 100 100 100 100 100 138
5.9.2 Fish
100 Good 80 Moderate 60 Poor 40 Very Poor 20 24 5 Extremely Poor 0 0 2 Valley lowland slopes upland
Figure GOU.2: Goulburn Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 139
The Goulburn Valley fish community was in Extremely Poor Condition. Alien species were 63% of total biomass and 58% of total abundance. The community had lost most of its native species richness and was dominated by alien fish, mainly trout.
Fish communities of the Goulburn Valley were surveyed in November–December 2005, at 21 sites in three Zones, yielding 726 fish. Analyses showed an Extreme Difference from Reference Condition:
• SR Fish Index (SR–FI) = 5 (CL 2–17). • Expectedness showed an Extreme (+) Difference from Reference Condition. • Nativeness showed an Extreme (+) Difference from Reference Condition. • The proportion of total biomass that was native (37%) was low. • Only 56% of predicted native species were collected. Figure GOU.2 shows sampling sites, Zones and corresponding SR–FI values, and Table GOU.2 shows Index values, Indicators, Metrics and derived variables. Six alien species were present in the Lowland and Slopes Zones, and three in the Upland Zone. Data for the Upland Zone indicated Extremely Poor Condition, with only 10% of total biomass and 29% of abundance contributed by native species. The Slopes Zone had similarly low native biomass and abundance, and only 27% of predicted native species (RC–F) were caught. These data produced an extremely low Nativeness score (SR–Fn = 9) and a Fish Index of zero (after rounding) for the Slopes Zone. The Goulburn Valley community had the equal-lowest Fish Index of all Valleys, with the Campaspe. Abundance was low, averaging 35 fish per site, and only 42% of individual fish were native. Fourteen native species and nine alien species were recorded. Minor variability in the Index and Indicators shows uniformity among Zones and sites, apart from Nativeness in the Lowland and Upland Zones. The Goulburn Valley showed an Extreme Difference from Reference Condition, with SR–FI = 5. Extreme Differences prevailed in the Slopes and Upland Zones, and a Very Large (+) Difference in the Lowland Zone. A new population of the nationally ‘threatened’ species, Barred galaxias, was located in the Goulburn Valley, with two Macquarie perch (another threatened species). A coastal-drainage native species, Climbing galaxias, was recorded at one site in the Lowland Zone. It was introduced via inter–basin flows from the Snowy Mountains Scheme and is regarded as an alien species in the Goulburn Valley. The average biomass of native species in the Lowland Zone (527 g per fish) was substantially higher than in other Zones, and resulted from catches of 20 Murray cod (mean weight 1,709 g) and five Golden perch (mean weight 1,516 g). Native fish in the Upland Zone were few and small. Rainbow trout and Brown trout dominated, and alien species together produced 90% of the biomass. The Slopes Zone is affected by cold- water pollution from Lake Eildon and only 27% of RC–F species were caught, while six alien species, including Roach, were 79% of fish biomass. Other alien species recorded were Carp, Goldfish, Eastern gambusia, Oriental weatherloach and Redfin perch. Table GOU.3 shows that freshwater catfish, River blackfish, Macquarie perch and Mountain galaxias were not caught in Zones where they were predicted to be common. Other species not 140 caught, but predicted to occur rarely or occasionally under Reference Condition, are also listed. They include Golden perch, Macquarie perch, River blackfish, Silver perch, Trout cod and several small, less well-known species. Mega-carnivore species were sparse in the Slopes Zone and absent from Upland Zone sites. Abnormalities were visible on fish in each Zone, averaging 2.4% across the Valley. From 2–5 Intolerant species were caught in each Zone.
Table GOU.2: Goulburn Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland
Fish Index 5 (2–17) 24 (8–43) 0 (0–10) 2 (2–25) Expectedness Indicator 16 (16–22) 25 (22–32) 10 (9–10) 18 (18–24) Nativeness Indicator 17 (2–37) 38 (2–62) 9 (0–32) 0 (0–48) Metric Total species 23 15 10 7 Native species 14 9 4 4 Predicted RC–F species count 25 22 15 11 Alien species 9 6 6 3 Caught/Predicted native species (%) 56 41 27 36 Numbers of fish Mean fish per site 35 22 38 44 Native individuals (%) 42 52 51 29 Fish biomass Biomass/site all species (g) 7,061 11,541 7,145 2,496 Mean native biomass/fish (g) 179 527 76 19 Mean alien biomass/fish (g) 223 514 306 73 Biomass native (%) 37 53 21 10
141
Table GOU.3: Goulburn Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Zone Total Native species Lowland Slopes Upland
Australian smelt 36 0 0 36 Barred galaxias 79 79 Bony herring 0 0 Carp gudgeons 9 0 0 9 Climbing galaxias* 2 2 Congolli 0 0 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 5 0 5 Freshwater catfish 0 0 Riffle galaxias 1 0 1 Golden perch 5 0 5 Macquarie perch 0 0 2 2 Mountain galaxias 114 0 114 Murray cod 20 1 21 Murray hardyhead 0 0 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 3 3 Obscure galaxias 0 0 0 0 River blackfish 1 0 0 1 Short-headed lamprey 0 0 Silver perch 1 0 1 Southern purple-spotted gudgeon 0 0 Southern pygmy perch 1 0 4 5 Trout cod 0 0 0 0 Two–spined blackfish 0 20 4 24 Un-specked hardyhead 0 0 Alien species
Brown trout 10 70 170 250 Carp 25 18 43 Eastern gambusia 5 5 Goldfish 1 1 Rainbow trout 9 45 54 Redfin perch 31 4 1 36 Roach 28 28 Oriental weatherloach 1 1
* Not native to the Goulburn Valley 142
5.9.3 Macroinvertebrates
100 Good 80 75 Moderate 60 59 50 Poor 40 41 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure GOU.3: Goulburn Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 143
The Goulburn Valley macroinvertebrate community was in Poor Condition, with the Lowland Zone in Poor Condition and the Slopes and Upland Zones both in Moderate Condition. Most sites had a depleted fauna, lacking most of their disturbance–sensitive families.
Thirty four sites were surveyed across three Zones of the Goulburn Valley in October 2005, yielding 9,607 macroinvertebrates in 88 families (62% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 50 (CL 49–59). • Moderate to low proportion of expected families (Filters OE = 26). • SIGNAL OE score just below Reference Condition (Filters SIGNAL OE = 97). SR–MI for the Goulburn Valley is in the mid-range of scores for all Valleys (cf. Macquarie, Loddon). The Lowland Zone showed a Large (–) Difference from Reference Condition (SR–MI = 41), and the Slopes and Upland Zones showed Large (+) and Moderate Differences from Reference Condition (SR–MI = 59, 75, respectively). Wide confidence intervals for SR–MI in the Upland Zone (26 points) indicated substantial variation among sites. Figure GOU.3 shows sampling sites, Zones and SR–MI values, and Table GOU.4 shows metrics and derived variables. Eighty five percent of expected families were recorded in the Valley, and family richness was less than Reference Condition at all sites bar one. Diversity was moderate to high (average 26 families per site), with some Slopes and Upland Zone sites being particularly diverse (c. 40 families per site), and Lowland Zone sites being less diverse (average 21 families per site). Most (74-75%) of the Valley fauna was found in the Slopes and Upland Zones (cf. 67% for the Lowland Zone). Table GOU.5 shows that Expected (Filters OE) scores indicated a substantial loss of expected families. Only one site in the Valley had a high Filters OE score, and five of the 34 sites had a low Filters OE score. Filters SIGNAL OE scores were high for the Slopes and Upland Zones, and most (11 of 16) sites in these Zones had a high score. The communities at most Slopes and Upland Zones sites were depleted, lacking most disturbance-sensitive families. Table GOU.6 shows ‘common’ and ‘rare’ families. Six common families included midges (Chiro- nominae, Podonominae), broad–shouldered water striders (Veliidae) and damselflies (Megapod- agrionidae). The 21 rare families included many aquatic insects. 144
Table GOU.4: Goulburn Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 50 41 59 75 (49–59) (34–47) (50–67) (59–85) Metrics Filters OE 26 23 28 34 (25–30) (20–26) (24–32) (28–4) Filters SIGNAL OE 97 90 107 115 (97–105) (84–94) (98–115) (100–119) Families Families per site 26 21 30 33 minimum – maximum 14–41 14–31 23–41 24–38 Total families 88 60 67 66
Table GOU.5: Goulburn Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 34 18 10 6
Filters OE High 1 1 Medium 28 13 10 5 Low 5 5 Filters SIGNAL OE High 11 7 4 Medium 20 16 2 2 Low 3 2 1
145
Table GOU.6: Goulburn Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 18 10 6 34 Number of families sampled 60 67 66 89 Percent of families in Basin 55.0 54.9 58.9 62.2 Percent of families in Valley 67 75 74 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Chironominae 100 100 100 100 Veliidae 94 90 100 94 Oligochaeta 78 100 83 85 Ecnomidae 50 30 33 41 Podonominae 30 17 12 Megapodagrionidae 10 33 9 Rare Ptilodactylidae 33 6 Tasimiidae 10 17 6 Atriplectididae 17 3 Blephariceridae 10 3 Ephydridae 6 3 Gelastocoridae 17 3 Glossiphoniidae 6 3 Gordiidae 17 3 Helicophidae 17 3 Janiridae 6 3 Limnephilidae 17 3 Lymnaeidae 6 3 Naucoridae 6 3 Nevrothidae 10 3 Paracalliopidae 17 3 Paramelitidae 17 3 Perthiidae 6 3 Psychodidae 6 3 Richardsonianidae 10 3 Sialidae 6 3 Tabanidae 17 3
146
5.9.4 Ecosystem Health
The Goulburn Valley river ecosystem was in Very Poor Health (all Zones: Very Poor). Fish abundance and biomass were dominated by alien species, and most expected species were absent. Some expected and disturbance-sensitive macroinvertebrate families were absent. There were substantial changes in annual flow volume and magnitude and the incidence of low- and high-flows, increasing downstream.
Summary Theme assessments are as follows (Table GOU.7): Hydrology Theme • Condition Index SR–HI = 34–100 at selected mainstem locations, indicating Poor Condition (Slopes, Lowland Zones: Very Poor to Poor; Upland Zone: Good). • High-flows showed a Moderate Difference from Reference Condition downstream of Lake Eildon and Large to Very Large Difference downstream of Goulburn Weir. • Incidence of low flows and the duration of zero flows ranged from Large Difference from Reference Condition downstream of Lake Eildon to an Extreme Difference downstream of Goulburn Weir. • Flow variability showed Moderate to Large Differences from Reference Condition at all sites downstream of Lake Eildon. • Flow seasonality showed a Very Large Difference from Reference Condition downstream of Eildon Reservoir, progressing from Large to Moderate Difference downstream. • Annual flow volumes were Near Reference Condition upstream of diversions, declining through Moderate to Extreme Differences from Reference Condition downstream. Mean and median volumes in the lower Goulburn River were reduced by 60% and 90%, respectively. Fish Theme • Condition Index SR–FI = 5 (CL 2–17), indicating Extremely Poor Condition (equal lowest for all Valleys). Condition differed among Zones (Lowland Zone: Very Poor; Slopes, Upland Zones: Extremely Poor). • Twenty three species caught, including nine alien species. • Predicted native species reduced in the Lowland (59%), Slopes (73%) and Upland Zones (64%). • Mean abundance 35 fish per site, mainly alien species (58%). • Biomass mainly alien species (63%). Macroinvertebrate Theme • Condition Index SR–MI = 50 (CL 49–59), indicating Poor Condition (Lowland, Slopes Zones: Poor; Upland Zone: Moderate). • Moderate diversity and low to moderate proportions of expected families in all Zones. • Disturbance-sensitive families were well-represented in the Slopes and Upland Zones but less so in the Lowland Zone. 147
Table GOU.7: Goulburn Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland
Poor to Poor to Hydrology Condition Poor Good Rating Very Poor Very Poor 5 (2–17) 24 (8–43) 0 (0–10) 2 (2–25) Fish Index Extremely Very Extremely Extremely Rating Poor Poor Poor Poor
Macroinvertebrate Index 50 (49–59) 41 (34–47) 59 (50–67) 75 (59–85) Rating Poor Poor Poor Moderate
Ecosystem Health Very Very Very Very Rating Poor Poor Poor Poor 148
5.10 Gwydir Valley
5.10.1 Hydrology
Figure GWY.1: Gwydir Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
The Hydrology Index for the Gwydir Valley indicates Moderate to Good Condition, with values of 72–99. The score for Tycannah Creek was 37, indicating Very Poor Condition.
The Gwydir River rises on the western slopes of the Great Dividing Range, near Armidale, and flows west. Near Moree it divides as the Gwydir and Lower Gwydir rivers. The latter divides as distributaries, some feeding wetland complexes. Copeton Dam (1,345 GL) provides instream storage on the upper Gwydir. The Gwydir and several of its tributaries and distributaries support irrigation. Diversions include opportunistic pumping to offstream storages. Figure GWY.1 shows values of the Hydrology Index, SR–HI, for five selected sites and Table GWY.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, 149 nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at the four sites on the Gwydir ranged from Near Reference Condition (SR–HI = 99) upstream of Copeton Dam to Moderate Difference from Reference Condition downstream (SR– HI = 72–79). Tycannah Creek, a tributary to the Lower Gwydir downstream of Moree, showed a Very Large Difference (SR–HI = 37). The indicators show:
• High-Flow Events: Site 5 showed an Extreme Difference from Reference Condition; Site 1 showed a Very Large Difference and the remaining sites were Near Reference Condition. High-flows have been reduced by 90–98% on many tributaries, and by up to 67% in the lower Gwydir River. • Low- and Zero-Flow Events: Sites 2, 3 and 5 showed a Moderate Difference from Reference Condition. Sites 1 and 3 were Near Reference Condition. There was a Large to Moderate Difference in several tributaries, and in the Gwydir downstream of Copeton Dam (but recovering downstream). Elsewhere, values were Near Reference Condition. • Variability: There was a Large Difference from Reference Condition at Site 5, reflecting substantial losses of high-flow events. Site 2 showed a Moderate Difference from Reference Condition and Sites 2, 3 and 4 were Near Reference Condition. Variation was Near Reference Condition for most sites, but Moderate to Large Differences were evident on some tributaries and in the Gwydir below Copeton Dam. • Seasonality: Site 3, downstream of Copeton Dam, showed a Large Difference from Reference Condition. Sites 1, 4, and 5 showed a Moderate Difference and at Site 1, downstream of the storage and major diversions, Seasonality was Near Reference Condition. Seasonality showed a Moderate to Large Difference at most sites. • Gross Volume: There was an Extreme Difference from Reference Condition at Site 5 and a Very Large Difference at Site 1. Annual flow volumes have been reduced by 80–95% on many tributaries and by 80% in the lower Gwydir River. The remaining sites were Near Reference Condition. Site 1 in the lower Gwydir and Site 5, a tributary, showed the effects of opportunistic harvesting of high flows with low values for HFE and GV (modelled current mean annual flows are 25% and 22%, respectively, of those predicted under natural conditions). Other tributaries in the Slopes and Upland Zones, including Copes, Warialda, Myall, Keera, Laura, Bakers and Halls Creeks, show a similar pattern, indicating widespread diversions of high flows. The Gwydir does not show a strong seasonal pattern of flow and the low Seasonality Indicator at Site 3 probably results from seasonal releases from Copeton Dam. In general, the flow regime of the Gwydir Valley is characterised by substantial reductions in annual volumes and high flow magnitudes, coupled with changes in seasonality in most tributaries and the Gwydir downstream of Copeton Dam.
150
Table GWY.1: Gwydir Valley: SR Hydrology Index and indicators. Sites are shown in Figure GWY.1. DS: downstream
Indicators Site Location SR–HI Zone HFE LZFE V S GV
1 Gwydir at Colymongle Lowland 72 33 89 82 95 39 2 Gwydir at Pallamallawa Slopes 79 90 62 76 65 82 3 Gwydir DS Copeton Dam Upland 81 96 61 81 43 89 4 Gwydir at Stonybatter Upland 99 100 100 100 74 100 Tycannah Ck at Horseshoe 5 Lagoon Slopes 37 6 64 55 72 4
151
5.10.2 Fish
100 Good 80 72 Moderate 60 51 Poor 45 40 36 Very Poor 20 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure GWY.2: Gwydir Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median
152
The Gwydir Valley fish community was in Poor Condition. Three–quarters of predicted native species were caught, but they were only a quarter of the total catch and a third of the biomass. The Upland Zone community was in Very Poor Condition. The Valley community had lost most of its native species richness and was dominated by alien fish.
Twenty eight sites across four Zones of the Gwydir Valley were surveyed in January, February and April 2007, yielding 5,905 fish. Analyses showed a Large Difference from Reference Condition:
• SR Fish Index (SR–FI) = 51 (CL 43–56). • Expectedness showed a Large Difference from Reference Condition. • Nativeness showed a Large (–) Difference from Reference Condition. • Eleven of 15 predicted native species (RC–F) were recorded. • Native fish were a quarter (26%) of the total catch and a third (35%) of total biomass. Figure GWY.2 shows sampling sites, Zones and corresponding SR–FI values, and Table GWY.2 shows Index values, Indicators, Metrics and derived variables. Eleven native species were recorded. There were six alien species in the Montane Zone, three and four in the Lowland and Upland Zones, respectively, and only two in the Slopes Zone. The Gwydir Valley Fish Index score was above average (eight Valleys had higher scores). The Slopes Zone community was in Moderate Condition (SR–FI = 72), better than the Upland and Montane Zones communities (SR–FI = 20, 36, respectively). Nativeness was low in Upland sites (SR–Fn = 12) and exceptionally low in Montane sites (SR–Fn = 4). There was moderate variation in Indicator scores among sites in all Zones. The Valley showed a Large Difference from Reference Condition (Lowland Zone: Large (±) Difference, Slopes Zone: Moderate (–) Difference, Upland Zone: Very Large (–) Difference, Montane Zone: Very Large Difference). Only 50% and 43% of RC–F species were recorded from the Lowland and Upland Zones, respectively, and 69% and 67% in the Slopes and Montane Zones. The native proportions of total biomass and native individuals were comparable except in the Montane Zone, where native fish were 3% of total abundance. Montane Zone native fish were larger (183 g) than alien species (10 g), so that the native proportion of biomass remained moderate. Fish were abundant (average 211 fish per site), but less so in the Lowland Zone (27 fish per site). Montane Zone sites had only 1–2 native species whereas sites in the Upland Zone had 1–4 species per site and Slopes Zone sites had 1–8 species. No native fish were caught at one site in each of the Upland and Montane Zones. Table GWY.3 shows that numbers of several popular native species were recorded, including Freshwater catfish, Golden perch and Murray cod. Among the alien species, Eastern gambusia and Redfin perch were extremely abundant, with moderate numbers of Carp and Goldfish, but Rainbow trout and Brown trout were rare. Murray-Darling rainbowfish and Freshwater catfish were not found in Zones where they were predicted to be common. Only single River blackfish and Spangled perch were caught in Zones where they were also predicted to be common. A Murray cod was caught at one Montane Zone site, but cod were not predicted in this Zone and the capture probably came from hatchery stock. 153
Less than 1% of fish across the Valley showed Abnormalities, but 3% were recorded in the Lowland Zone. Intolerant species were recorded only in the Montane Zone. Mega-carnivores were common in all Zones.
Table GWY.2: Gwydir Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland Montane
Fish Index 51 (43–56) 45 (33–61) 72 (55–85) 20 (8–39) 36 (36–38) Expectedness Indicator 50 (42–55) 38 (38–47) 70 (52–78) 36 (25–45) 51 (51–51) Nativeness Indicator 46 (31–56) 52 (28–76) 65 (42–77) 12 (4–37) 4 (4–17) Metric Total species 17 9 11 10 10 Native species 116964 Predicted RC–F species count 15 12 13 14 6 Alien species 63246 Caught/Predicted native species (%) 73 50 69 43 67 Numbers of fish Mean fish per site 211 27 286 322 209 Native individuals (%) 26 37 43 25 3 Fish biomass Biomass/site all species (g) 9,240 1,845 24,306 7,693 3,118 Mean native biomass/fish (g) 59 71 56 52 183 Mean alien biomass/fish (g) 38 68 107 14 10 Biomass native (%) 35 38 28 56 38
154
Table GWY.3: Gwydir Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Zone Total Native species Lowland Slopes Upland Montane
Australian smelt 1 159 0 160 Bony herring 46 36 82 Carp gudgeons 10 401 558 10 979 Darling River hardyhead 0 0 0 0 Freshwater catfish 0 6 2 4 12 Golden perch 5 11 1 17 Mountain galaxias 0 30 30 Murray cod* 3 33 7 1 44 Murray–Darling rainbowfish 0 117 0 117 Olive perchlet 0 0 0 0 River blackfish 1 1 2 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 0 Spangled perch 4 1 0 5 Un-specked hardyhead 0 92 5 97
Alien species
Brown trout 2 2 Carp 71 72 9 152 Eastern gambusia 16 1072 767 982 2,837 Goldfish 31 76 87 194 Rainbow trout 4 4 Redfin perch 831 340 1,171
* Not native in the Montane Zone, probably from hatchery stock 155
5.10.3 Macroinvertebrates
100 Good 80 Moderate 60 56 58 58 59 Poor 40 43 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure GWY.3: Gwydir Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 156
The Gwydir Valley macroinvertebrate community was in Poor Condition throughout, with communities at most sites being impoverished and having lost disturbance-sensitive families.
Thirty seven sites were surveyed across four Zones of the Gwydir Valley in October 2005, yielding 7,777 macroinvertebrates in 70 families (50% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 56 (CL 51–61). • A moderate proportion of expected families (Filters OE = 32). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 91). SR–MI for the Gwydir Valley is the seventh highest score of all Valleys (cf. Ovens, Condamine). The Lowland, Slopes and Upland Zone communities all showed a Large (+) Difference from Reference Condition (SR–MI = 58–59), and Montane Zone sites showed a Large (–) Difference (SR–MI = 43). Wide confidence intervals for SR–MI in Lowland and Slopes Zones (17–26 points) indicate substantial variation among sites. Figure GWY.3 shows sampling sites, Zones and SR–MI values, and Table GWY.4 shows metrics and variables. Sixty nine percent of expected families were recorded in the Valley. Family richness was less than Reference Condition at 33 of the 37 sites. Diversity was moderate to high (average 24 families per site), and least at Lowland Zone sites (average 19 families per site). Most (67–80%) of the Valley fauna was found in each of the Zones. Table GWY.5 shows that Expected (Filters OE) scores indicated moderate to substantial loss of expected families, with significant variation among Slopes Zone sites. Only one site had a low Filters OE score, and four sites had a high Filters OE score. Filters SIGNAL OE scores were near Reference Condition in the Lowland and Slopes Zones, but less in the Montane Zone. The communities in all Zones were impoverished and lacking disturbance–sensitive families. Table GWY.6 shows ‘common’ and ‘rare’ families. Eight common families included crayfish (Parastacidae), little basket shells and snails (Corbiculidae, Thiaridae), mayflies (Caenidae) and water scorpions (Nepidae). Notable among these are the Thiaridae, a group of high-spired, operculate snails that are now rare in many areas, but formerly were common throughout the Basin. The 11 rare families included dragonflies and damselflies (Corduliidae, Diphlebiidae, Megapodagrionidae), river snails (Viviparidae) and a variety of aquatic beetles and flies. The viviparid snails, like the thiarids, were once very common. 157
Table GWY.4: Gwydir Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 56 58 58 59 43 (51–61) (48–69) (52–69) (46–72) (37–48) Metrics Filters OE 32 33 32 35 27 (29–35) (26–38) (31–38) (26–42) (22–28) Filters SIGNAL OE 91 94 96 88 80 (87–95) (86–100) (84–103) (83–91) (79–87) Families Families per site 24 19 25 32 26 minimum – maximum 13–39 13–26 16–32 17–39 22–29 Total families 70 47 55 55 54
Table GWY.5: Gwydir Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 37 11 13 6 7
Filters OE High 4 2 1 1 Medium 32 9 12 4 7 Low 1 1 Filters SIGNAL OE High 6 2 4 Medium 27 8 8 6 5 Low 4 1 1 2 158
Table GWY.6: Gwydir Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 11 13 6 7 37 Number of families sampled 48 56 55 56 72 Percent of families in Basin 44.0 45.9 49.1 56.6 50.3 Percent of families in Valley 67 78 76 78 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY
Common Caenidae 82 85 100 71 84 Parastacidae 100 38 50 100 70 Gerridae 64 62 67 29 57 Tabanidae 64 54 67 49 Corbiculidae 9 38 67 29 32 Nepidae 9 38 33 43 30 Protoneuridae 54 33 14 27 Thiaridae 15 83 19 Rare Corduliidae 36 23 19 Diphlebiidae 33 5 Siphonotidae 9 14 5 Dixidae 14 3 Ephydridae 8 3 Haliplidae 17 3 Megapodagrionidae 14 3 Naucoridae 14 3 Richardsonianidae 8 3 Sciomyzidae 9 3 Viviparidae 9 3
159
5.10.4 Ecosystem Health
The Gwydir Valley river ecosystem was in Poor Health (Lowland, Slopes Zones: Poor; Upland, Montane Zones: Very Poor). Fish abundance and biomass were dominated by alien species, and several expected species were absent. Many expected and some disturbance-sensitive macro- invertebrate families were absent. Annual volumes and high flows were reduced, and there were changes in seasonality in most tributaries and the Gwydir below Copeton Dam.
Summary Theme assessments are as follows (Table GWY.7): Hydrology Theme • Condition Index SR–HI = 72–99 at selected mainstem locations, indicating Moderate to Good Condition (Lowland Zone: Moderate; Slopes Zone: Poor; Upland: Moderate to Good). The single Montane Zone site was in Poor Condition. • High-flow magnitudes have been reduced by 90–98% in tributary streams, and by up to 67% in the lower Gwydir River. • Incidence and duration of low and zero flows showed a Large to Moderate Difference from Reference Condition in several tributaries, and the Gwydir River downstream of Copeton Dam, but recovered downstream. Other sites were Near Reference Condition. • Flow variability was Near Reference Condition for most sites. There were Moderate to Large Differences in some tributaries and in the Gwydir below Copeton Dam. • Seasonality showed a Moderate Difference from Reference Condition at most sites. • Annual flow volume have been reduced by 80–95% in many tributary streams and by 80% in the lower Gwydir River. Fish Theme • Condition Index SR–FI = 51 (CL 43–56), indicating Poor Condition (above the average (SR–FI = 37) for all Valleys). Condition differed among Zones (Lowland Zone: Poor; Slopes Zone: Moderate; Upland, Montane Zones: Very Poor). • Seventeen species caught, including six alien species. • Predicted native species reduced in the Lowland (50%), Slopes (31%), Upland (57%) and Montane Zones (33%). • Mean abundance 211 fish per site, mainly alien species (74%). • Biomass mainly alien species (65%). Macroinvertebrate Theme • Condition Index SR–MI = 56 (CL 51–61), indicating Poor Condition (all Zones: Poor). • Moderate to high diversity, but losses of expected families in all Zones. • Some losses of disturbance-sensitive families in all Zones. 160
Table GWY.7: Gwydir Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland Montane
Moderate Moderate Hydrology Condition Moderate Poor Poor Rating to Good to Good 20 (8–39) 36 (36–38) Fish Index 51 (43–56) 45 (33–61) 72 (55–85) Very Very Rating Poor Poor Moderate Poor Poor
Macroinvertebrate Index 56 (51–61) 58 (48–69) 58 (52–69) 59 (46–72) 43 (37–48) Rating Poor Poor Poor Poor Poor
Ecosystem Health Very Very Poor Poor Poor Rating Poor Poor
161
5.11 Kiewa Valley
5.11.1 Hydrology
Figure KIE.1: Kiewa Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for all sites were 100, indicating Good Condition throughout.
The Kiewa River rises on the Bogong High Plains on the Great Dividing Range as the Kiewa River West Branch, rising near Mt Hotham, and the Kiewa River East Branch, rising above Falls Creek township. The West Branch is the larger, carrying about six times the flow of the East Branch. They join near Mount Beauty and flow northward to join the Murray downstream of Lake Hume. Tributaries to the Kiewa Lowland Zone include Yackandandah, Middle, House and Huon Creeks. The Valley is narrow and steep for much of its length, but the river develops a broad floodplain in the lowermost 20% of its length. Storages on the Kiewa are primarily for power generation, limiting their effects on the long-term pattern and volume of flow. Rocky Valley Dam (28.4 GL), on the East Branch, is the main 162 storage, with a number of small associated (<1 GL) pondages that experience short-term water- level fluctuations and may create similar changes in flow immediately downstream. Figure KIE.1 shows values of the Hydrology Index for selected sites and Table KIE.1 shows the index and indicator values for five sites in the Kiewa Valley. These sites provide examples of hydrological conditions in the main streams in the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at five sites on the Kiewa generally was Near Reference Condition (SR–HI = 100). The indicators show:
• High-Flow Events: All sites were Near Reference Condition. • Low- and Zero-Flow Events: All sites were Near Reference Condition. • Variability: All sites were Near Reference Condition. • Seasonality: All sites were Near Reference Condition. • Gross Volume: Near Reference Condition at all but a small number of sites. The indicators show that flows in the Kiewa are unaffected by current management, being Near Reference Condition at nearly all sites. Little water is diverted (for example, modelled current flows at Site 1, near the Valley terminus, are 99% of modelled natural flows), and there appears to be no change to seasonal patterns or to specific flow events. Note, however, that the indicators (and Hydrology Index) are based on monthly flow data that may not reflect short-term changes resulting from electricity generation.
Table KIE.1: Kiewa Valley: SR Hydrology Index and indicators. Sites are shown in Figure KIE.1. US: upstream; DS: downstream
Indicators Site Location SR–HI Zone HFE LZFE V S GV
1 Kiewa River outlet Lowland 100 100 97 98 92 100 2 Kiewa River at Kiewa Lowland 100 100 97 98 94 100 3 Kiewa River US Running Ck Slopes 100 100 100 99 95 100 Kiewa River West Branch 4 DS Mt Beauty offtake Slopes 100 100 100 99 100 98 Kiewa River East Branch 5 DS Mountain Ck Outlet Slopes 100 100 100 100 100 100
163
5.11.2 Fish
100 Good 80 Moderate 60 56 Poor 40 26 28 Very Poor 20 Extremely Poor 0 1 Valley lowland slopes upland
Figure KIE.2: Kiewa Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 164
The Kiewa Valley fish community was in Very Poor Condition. The Lowland, Slopes and Upland Zone communities were in Very Poor, Poor and Extremely Poor Condition, respectively. Alien species were 90% of total biomass and 57% of total abundance. The community had lost most of its native species richness and was dominated by alien fish.
Fish communities of the Kiewa Valley were surveyed in March 2006. Twenty one sites were sampled across three altitudinal Zones, yielding 2,174 fish. Analyses showed a Very Large (±) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 26 (CL 19–44). • Expectedness showed a Large (–) Difference from Reference Condition. • Nativeness showed a Very Large (–) Difference from Reference Condition. • Alien species made up over half of the catch and 90% of the biomass. Figure KIE.2 shows sampling sites, Zones and corresponding SR–FI values, and Table KIE.2 shows Index values, Indicators, Metrics and derived variables. Eleven native species and eight alien species were caught. The Kiewa Valley showed a Very Large (±) Difference from Reference Condition, with SR–FI = 26 (Lowland Zone: Very Large (±) Difference, Slopes Zone: Large (+) Difference, Upland Zone: Extreme Difference). The Valley Fish Index was low, with only eight Valleys having a lower score. Only 65% of the predicted native species (RC–F) were caught; native fish were 46% of total abundance but only 10% of biomass. Condition was exceptionally low in the Upland Zone, with a Fish Index of one, a mere 2% native biomass and only 4% native individuals. The Slopes Zone community was in better Condition (SR–FI = 56) and significant variation was evident there in scores for Nativeness and Expectedness. Scores in the Lowland Zone were intermediate. Only 53%, 69% and 33% of predicted (RC–F) species were recorded from the Lowland, Slopes, and Upland Zones, respectively, with six, six and three alien species, respectively. The Upland Zone, like the higher-altitude reaches of other Valleys, was expected to have fewer RC–F species than other Zones. This highlights the paucity of individual native species in samples. Although nine native species were captured in the Lowland Zone, their distribution was patchy and only two sites yielded more than two native species. Native species were patchily distributed also in the Slopes Zone and, again, only two sites had more than two native species. In the Upland Zone two sites yielded native fish (one species each). Brown trout and rainbow trout dominated the Valley community, being very numerous in patches and present at all Upland Zone sites. Other alien species, especially Eastern gambusia, Goldfish and Carp, were widespread and abundant. The recently-invading alien, Oriental weatherloach, was found at two Lowland Zone sites. Redfin perch were caught occasionally. A native species from coastal drainages, the Climbing galaxias, was caught in the Upland Zone. This species was introduced via inter–basin flows from the Snowy Mountains Scheme and is treated as an alien species in the Kiewa Valley. Table KIE.3 shows that Mountain galaxias were not caught at any sites in the Upland Zone, although they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Macquarie perch, Silver perch and Trout cod, and several small, less well-known species. 165
Five Intolerant species were recorded, and <1% of fish had Abnormalities. No Mega-carnivores were caught in the Upland Zone.
Table KIE.2: Kiewa Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland
Fish Index 26 (19–44) 28 (17–68) 56 (42–83) 1 (1–1) Expectedness Indicator 39 (34–55) 34 (34–73) 62 (51–87) 15 (15–15) Nativeness Indicator 20 (7–30) 27 (7–62) 37 (16–53) 0 (0–0) Metric Total species 19 15 15 4 Native species 11 9 9 1 Predicted RC–F species count 17 17 13 3 Alien species 8 6 6 3 Caught/Predicted native species (%) 65 53 69 33 Numbers of fish Mean fish per site 104 120 141 50 Native individuals (%) 43 19 77 4 Fish biomass Biomass/site all species (g) 11,212 9,600 21,033 3,003 Mean native biomass/fish (g) 26 44 22 29 Mean alien biomass/fish (g) 171 88 587 62 Biomass native (%) 10 10 11 2
166
Table KIE.3: Kiewa Valley: numbers of native fish by Zone. Predicted species (RC–F list) are shown by numbers; species not predicted are shown by blanks
Zone Total Native species Lowland Slopes Upland
Australian smelt 51 195 246 CCarp gudgeons 8 2 10 Climbing galaxias * 3 3 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 0 0 Riffle galaxias 0 37 0 37 Golden perch 1 1 2 Macquarie perch 0 0 0 Mountain galaxias 0 389 0 389 Murray cod 14 12 26 Flat-headed galaxias 0 0 0 Obscure galaxias 8 1 9 River blackfish 66 33 99 Silver perch 0 0 Southern pygmy perch 3 0 3 Trout cod 1 0 1 Two–spined blackfish 7 92 14 113 Un-specked hardyhead 0 0
Alien species
Brown trout 1 40 116 157 Carp 37 55 92 Eastern gambusia 549 100 649 Goldfish 58 3 61 Rainbow trout 11 215 226 Redfin perch 6 13 19 Oriental weatherloach 32 32
* Not native to the Kiewa Valley 167
5.11.3 Macroinvertebrates
100 Good 80 75 Moderate 60 59 59 Poor 40 43 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure KIE.3: Kiewa Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 168
The Kiewa Valley macroinvertebrate community was in Poor Condition. The Lowland and Slopes Zone communities were in Poor Condition, and the Upland Zone community was in Moderate Condition. Most sites had depleted diversity, but retained many of their disturbance-sensitive families.
Thirty five sites were surveyed across three Zones of the Kiewa Valley in March 2005, yielding 12,159 macroinvertebrates in 84 families (57% of Basin families). Analyses showed a Large (+) Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 59 (CL 58–70). • Moderate proportion of expected families (Filters OE = 29). • SIGNAL OE score equivalent to Reference Condition (Filters SIGNAL OE = 105). SR–MI for the Kiewa Valley was the equal fourth-highest score of all Valleys (cf. Mitta Mitta). The Lowland Zone community showed a Large (–) Difference from Reference Condition (SR–MI = 43), and the Slopes and Upland Zones showed Large (+) and Moderate (+) Differences (SR–MI = 59, 75, respectively). In the Upland Zone, the wide confidence interval for SR–MI (26 points), indicating substantial variation in condition between sites. Figure KIE.3 shows sampling sites, Zones and SR–MI values, and Table KIE.4 shows metrics and derived variables. Eighty one percent of expected families were recorded, and family richness was less than Reference Condition at all sites except one. Diversity was moderate to high (average 30 families per site), being highest at some Upland Zone sites and least at Lowland Zone sites (average 24 families per site). Most (79 and 82%) of the Valley fauna was found in the Slopes and Upland Zones (cf. 59% for the Lowland Zone). Table KIE.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Three Upland Zone sites had a high Filters OE score, and only one site had a low score. Filters SIGNAL OE scores were high for the Slopes and Upland Zones, and most sites (20 of 27) in these Zones had a high score. The communities at most Slopes and Upland Zones were depleted, but retained most disturbance-sensitive families. Table KIE.6 shows ‘common’ and ‘rare’ families. Twenty five common families included 19 families of aquatic insects that indicate good water- and habitat-quality (e.g. mayflies, caddisflies, stoneflies). The 19 rare families included many lowland and slow–flowing water groups such as shrimps (Atyidae) and other Crustacea (Parastacidae, Phreatoicopsidae), diving beetles (Dytiscidae, Hydraenidae), bugs (Corixidae, Notonectidae) and snails (Planorbidae). 169
Table KIE.4: Kiewa Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 59 43 59 75 (58–70) (38–50) (53–64) (65–91) Metrics Filters OE 29 24 29 34 (28–33) (24–26) (26–30) (30–41) Filters SIGNAL OE 105 91 104 116 (101–110) (83–104) (100–109) (107–120) Families Families per site 30 24 30 34 minimum – maximum 19–41 19–26 22–35 28–41 Total families 84 48 69 65
Table KIE.5: Kiewa Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 35 8 16 11
Filters OE High 3 3 Medium 31 7 16 8 Low 1 1 Filters SIGNAL OE High 22 2 10 10 Medium 11 4 6 1 Low 2 2
170
Table KIE.6: Kiewa Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 8 16 11 35 Number of families sampled 48 67 65 82 Percent of families in Basin 44.0 54.9 58.0 57.3 Percent of families in Valley 59 82 79 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Baetidae 100 100 100 100 Chironominae 100 100 100 100 Leptoceridae 100 100 100 100 Orthocladiinae 100 100 100 100 Leptophlebiidae 88 100 100 97 Acarina 75 94 100 91 Elmidae 63 100 100 91 Hydropsychidae 75 100 91 91 Hydrobiosidae 63 94 100 89 Oligochaeta 100 88 82 89 Tipulidae 50 94 100 86 Aeshnidae 63 75 73 71 Psephenidae 94 73 66 Philorheithridae 44 91 49 Calocidae 31 91 43 Corydalidae 13 44 64 43 Eustheniidae 13 73 29 Notonemouridae 6 73 26 Diamesinae 6 55 20 Helicophidae 64 20 Tasimiidae 19 36 20 Osmylidae 27 9 Thaumaleidae 27 9 Ameletopsidae 18 6 Gelastocoridae 13 6 Rare Corixidae 100 81 45 74 Dytiscidae 88 69 27 60 Notonectidae 88 31 18 40 Hydraenidae 38 19 18 23 Atyidae 50 13 17 Coenagrionidae 38 6 11 Parastacidae 25 6 9 Nesamelitidae 18 6 Aphroteniinae 9 3 Corbiculidae 9 3 Culicidae 13 3 Libellulidae 13 3 Muscidae 6 3 Nepidae 6 3 Phreatoicopsidae 9 3 Planorbidae 13 3 Psychodidae 6 3 Pyralidae 13 3 Tabanidae 9 3 171
5.11.4 Ecosystem Health
The Kiewa Valley river ecosystem was in Very Poor Health (Lowland Zone: Very Poor; Slopes Zone: Poor; Upland Zone: Very Poor). Fish abundance and biomass were dominated by alien species, and several expected fish species were absent. Many expected macroinvertebrate families were absent. In nearly all sites the flow regime indicators were Near Reference Condition.
Summary Theme assessments are as follows (Table KIE.7): Hydrology Theme • Condition Index SR–HI = 100 at selected mainstem locations, indicating Good Condition throughout. • High-flow magnitudes were Near Reference Condition. • Incidence and duration of low and zero flows were Near Reference Condition, with the exception of one site. • Flow variability was Near Reference Condition. • Seasonality of flows was Near Reference Condition. • Annual flow volumes were Near Reference Condition in all sites. Fish Theme • Condition Index SR–FI = 26 (CL 19–44), indicating Very Poor Condition, in the low range for all Valleys. Condition differed among Zones (Lowland Zone: Very Poor; Slopes Zone: Poor; Upland Zone: Extremely Poor). • Nineteen species caught, including eight alien species. • Predicted native species reduced in the Lowland (47%), Slopes (31%) and Upland Zones (67%). • Mean abundance 104 fish per site, mainly alien species (67%). • Biomass mainly alien species (90%). Macroinvertebrate Theme • Condition Index SR–MI = 59 (CL 58–70), indicating Poor Condition (Lowland, Slopes Zones: Poor; Upland Zone: Moderate). • Moderate to high diversity and low to moderate proportions of expected families in all Zones. • Good representation of disturbance-sensitive families at most sites, but reduced in the Lowland Zone.
172
Table KIE.7: Kiewa Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland
Hydrology Condition Good Good Good Good Rating 26 (19–44) 34 (17–68) 1 (1–1) Fish Index 57 (42–83) Very Very Extremely Rating Poor Poor Poor Poor
Macroinvertebrate Index 59 (58–70) 45 (38–50) 59 (53–64) 75 (65–91) Rating Poor Poor Poor Moderate
Ecosystem Health Very Very Very Poor Rating Poor Poor Poor
173
5.12 Lachlan Valley
5.12.1 Hydrology
Figure LAC.1: Lachlan Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for selected sites on the Lachlan mainstem were 72–100, indicating Moderate to Good Condition (Lowland Zone: Moderate Condition; Slopes Zone: Moderate to Good Condition; Upland and Montane Zones: Good Condition).
The Lachlan River rises in the foothills of the Great Dividing Range near Gunning and arcs westward, fed by foothill tributaries, terminating in the Great Cumbung Swamp. The main instream storage is Wyangala Dam (1,218 GL), at the junction of the Lachlan and Abercrombie rivers. In addition there is Carcoar Dam (36 GL) on the Belubula River, two offstream storages (Lake Brewster: 153 GL; Lake Cargelligo: 36 GL) and numerous on-farm storages. There is significant irrigation development between Forbes and Condobolin, and in the vicinity of Hillston. Figure LAC.1 shows values of the Hydrology Index for five selected sites and Table LAC.1 shows the index and indicator values. These sites provide examples of hydrological conditions in 174 the main streams across the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). The Lachlan upstream of storages and diversions (Site 5) was Near Reference Condition (SR–HI = 100). Other sites showed a Moderate Difference (SR–HI = 72–74). Site 5 was Near Reference Condition for all indicators. At Sites 1–4, the indicators show:
• High-Flow Events: All four selected sites showed a Moderate Difference from Reference Condition. • Low- and Zero-Flow Events: Site 1 was Near Reference Condition; Sites 2–4 showed a Moderate Difference. • Variability: Site 1 showed a Moderate Difference; Sites 2–4 were Near Reference Condition. • Seasonality: Site 4 showed a Very Large Difference from Reference Condition; Site 2 showed a Large Difference and Sites 1 and 3 showed a Moderate Difference. Seasonality in the Lachlan and Belubula Rivers downstream of Wyangala and Carcoar Dams showed a Very Large Difference from Reference Condition, tending toward a Moderate Difference downstream. It was Near Reference Condition elsewhere. • Gross Volume: Site 1 showed a Large Difference from Reference Condition and Site 4 showed a Moderate Difference, reflecting regional diversions. Sites 2–3 were Near Reference Condition. High- and low-flows and annual flows in the Lachlan Lowland and Slopes Zones were equivalent to Large Differences from Reference Condition. The changes corresponded to reductions in mean and median annual volumes by 20–40% and 30–50%, respectively. No substantial changes were observed in the Upland and Montane Zones, or in tributaries. Site 1, with substantially-changed GV, HFE and V indices, reflected changes due to diversions harvesting of high flows. At Site 4, downstream of Wyangala Dam, there was some loss of Gross Volume (modelled current flow is about 3% less than modelled natural flow), but the main change was to Seasonality, through augmented summer-autumn flows. Site 5, high in the catchment, showed no change from the modelled natural hydrograph. In general, the Lachlan Valley flow regime was unchanged from Reference Condition except in the Lachlan and Belubula rivers downstream of Wyangala and Carcoar storages, respectively. These reaches showed significant changes in the magnitudes of high, low and annual flows, and in flow variability and seasonality.
Table LAC.1: Lachlan Valley: SR Hydrology Index and indicators. Sites are shown in Figure LAC.1. DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Lachlan at Booligal Lowland 72 64 89 74 69 50 2 Lachlan at Willandra Weir Lowland 74 71 62 98 53 96 3 Lachlan at Jemalong Weir Slopes 72 70 60 93 66 84 4 Lachlan DS Wyangala Dam Slopes 72 75 77 86 39 73 5 Lachlan at Narrawa Upland 100 100 100 100 100 100 175
5.12.2 Fish
100 Good 80 Moderate 60 Poor 40 40 40 29 Very Poor 20 14 Extremely Poor 0 1 Valley lowland slopes upland montane
Figure LAC.2: Lachlan Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 176
The Lachlan Valley fish community was in Extremely Poor Condition. Loss of species richness, low abundance of native species and intrusions by alien species were apparent, especially in the Slopes and Upland Zones.
Twenty eight sites across four Zones of the Lachlan Valley were sampled in January, February and March 2006, and 3,433 fish were caught. Analyses indicated an Extreme (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 14 (CL 5–28). • Only half the expected native species were recorded. • Nativeness showed a Very Large (±) Difference from Reference Condition. Figure LAC.2 shows sampling sites, Zones and corresponding SR–FI values, and Table LAC.2 shows Index values, Indicators, Metrics and derived variables. Across the Valley, 10 native species and six alien species were caught. The Lachlan Valley community showed an Extreme (+) Difference from Reference Condition (Lowland Zone: Large (–) Difference, Slopes Zone: Extreme Difference, Upland Zone: Very Large (±) Difference, Montane Zone: Large (–) Difference). Thae Lachlan was ranked with the equal fifth-lowest score (cf. Castlereagh, Murrumbidgee, Upper Murray). The Slopes Zone community showed an Extreme Difference from Reference Condition, with none of the predicted 19 native species other than Carp gudgeons and a single Australian smelt. The Slopes Zone community also showed extremely low Nativeness, and exceptionally low native biomass, (0.4% of total fish biomass). In the Montane Zone, only one of 11 predicted species was caught, hence Expectedness was low. Table LAC.3 shows that 10 of the 20 predicted (RC–F) species were found, and their representation in the Slopes and Montane Zones (11% and 10%, respectively) was extremely low. Species not caught in Zones where they were predicted to be common under Reference Condition included Carp gudgeons and Macquarie perch. Other missing species included Silver perch, River blackfish, Golden perch, Macquarie perch, Trout cod, Murray cod, Southern purple-spotted gudgeon and Freshwater catfish. Bony herring and especially Murray-Darling carp gudgeon dominated the native species. Only three Upland Zone sites had more than two native species. In the Montane Zone, the sole native species caught was Mountain galaxias. Carp and Eastern gambusia dominated the alien species, occurring abundantly at most Lowland and Slopes Zone sites. In the Upland Zone, Carp, Goldfish, Eastern gambusia and Redfin perch occurred, sometimes abundantly. In the Montane Zone, Eastern gambusia was abundant and Carp, Rainbow trout and Brown trout were found occasionally. A wide range of catches was recorded, from 4–720 fish per site. Average abundances also varied, from 85 fish per site in the Slopes Zone to 195 in the Lowland Zone. Over two-thirds of individual fish in the Valley were native, but these averaged only 30% of the total biomass because of the dominance of small Murray-Darling carp gudgeon. Across the Valley, fewer than 2% of fish showed Abnormalities, most of them in the Lowland Zone. Mega-carnivore species occurred only in the Lowland and Upland Zones. Two Intolerant species were recorded in the Montane Zone. 177
Table LAC.2: Lachlan Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland Montane
Fish Index 14 (5–28) 40 (13–56) 1 (0–9) 29 (18–51) 40 (12–40) Expectedness Indicator 19 (11–28) 39 (19–43) 0 (0–1) 34 (34–46) 2 (2–2) Nativeness Indicator 30 (19–47) 37 (12–71) 16 (0–32) 27 (13–62) 89 (37–100) Metrics Total species 16 9 4 11 5 Native (RC–F) species 10 6 2 7 1 Predicted RC–F species count 21 16 18 13 10 Alien species 6 3 2 4 4 Caught/Predicted native species (%) 50 38 11 54 10 Numbers of fish Mean fish per site all species 123 197 85 97 110 Native individuals (%) 68 76 55 56 75 Fish biomass Total biomass/site all species (g) 4,508 8,404 3,809 5,490 91 Mean native biomass/fish (g) 11 18 0 16 1 Mean alien biomass/fish (g) 91 119 100 109 1 Biomass native (%) 21 32 0 16 83
178
Table LAC.3: Lachlan Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes Upland Montane
Australian smelt 3 1 8 12 Bony herring 249 0 249 Carp gudgeons 758 281 40 0 1,079 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 0 0 3 3 Freshwater catfish 0 0 0 0 0 Golden perch 5 0 5 0 10 Macquarie perch 0 0 0 0 Mountain galaxias 0 376 579 955 Murray cod 11 0 0 0 11 Murray hardyhead 0 0 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 0 0 0 Olive perchlet 0 0 0 River blackfish 0 1 0 1 Silver perch 0 0 3 3 Southern purple-spotted gudgeon 0 0 0 0 0 Southern pygmy perch 0 0 0 0 0 Trout cod 0 0 0 0 Un-specked hardyhead 15 0 15
Alien species
Brown trout 4 4 Carp 166 26 38 2 232 Eastern gambusia 100 201 275 186 762 Goldfish 71 11 82 Rainbow trout 2 2 Redfin perch 13 13 179
5.12.3 Macroinvertebrates
100 Good 80 Moderate 60 59 53 53 48 Poor 40 42 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure LAC.3: Lachlan Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 180
The Lachlan Valley macroinvertebrate community generally was in Poor Condition, especially in the Slopes Zone, with substantial loss of ‘expected’ families. Most sites had lost disturbance- sensitive families.
Thirty five sites were surveyed across four Zones of the Lachlan Valley in November 2004, yielding 11,087 macroinvertebrates and 69 families (49% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 53 (CL 49–56). • Moderate proportion of expected families (Filters OE = 30). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 92). SR–MI for the Lachlan Valley was in the mid–range of scores of all Valleys (cf. Darling, Namoi). Most site communities showed a Large Difference from Reference Condition, with the Slopes Zone in poorest condition. Wide confidence intervals for SR–MI in the Slopes and Montane Zones (23–26 points) indicated substantial variation in condition among sites. Figure LAC.3 shows sampling sites, Zones and SR–MI values, and Table LAC.4 shows metrics and derived variables. Some 67% of expected families were recorded in the Valley. Family richness was less than Reference Condition at 91% of sites. Diversity was moderate (average 24 families per site), increasing with altitude, with Lowland Zone sites being least diverse (average 20 families per site). Higher proportions (79%) of the Valley fauna were in the Slopes and Upland Zones (cf. 67 and 71% for the Lowland and Montane Zones). Expected (Filters OE) scores indicated substantial loss of expected families, with significant variation among sites in the Slopes and Montane Zones. Three sites in the Valley had a low Filters OE score, and three sites had a high score. Filters SIGNAL OE scores were near Reference Condition 40% of Lowland Zone sites, but less in the other Zones, where the fauna at most sites was impoverished and missing disturbance-sensitive families (Table LAC.5). Table LAC.6 shows ‘common’ and ‘rare’ families. Seven common families included dragonflies and damselflies (Corduliidae, Megapodagrionidae), mayflies (Baetidae), and water beetles (Hydrophilidae). The 12 ‘rare’ families included several caddisfly, stonefly and mayfly families known from cool flowing waters (Calamoceratidae, Conoesucidae; Notonemouridae, Onisci- gastridae). Thiarid snails, a group which has declined throughout the Basin, are particularly rare in the Lachlan Valley. 181
Table LAC.4: Lachlan Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 53 59 42 48 53 (49–56) (56–70) (30–56) (43–51) (50–73) Metrics Filters OE 30 31 24 28 32 (27–32) (29–36) (19–33) (27–30) (31–40) Filters SIGNAL OE 92 99 88 85 85 (89–95) (97–105) (81–94) (79–88) (82–92) Families Families per site 24 20 22 29 34 minimum – maximum 10–36 15–27 10–31 25–34 33–36 Total families 69 46 55 54 49
Table LAC.5: Lachlan Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 35 14 11 7 3
Filters OE High 3 2 1 Medium 29 12 7 7 3 Low 3 3 Filters SIGNAL OE High 6 6 Medium 25 8 9 5 3 Low 4 2 2 182
Table LAC.6: Lachlan Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 14 11 7 3 35 Number of families sampled 47 55 55 50 70 Percent of families in Basin 43.1 45.1 49.1 50.5 49.0 Percent of families in Valley 67 79 79 71 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY Very Common Baetidae 86 100 100 100 94 Notonectidae 93 100 86 100 94 Veliidae 86 100 86 67 89 Hydrophilidae 79 91 71 67 80 Corduliidae 64 45 71 100 63 Glossiphoniidae 18 71 67 26 Megapodagrionidae 14 67 9 Rare Calamoceratidae 14 33 6 Conoesucidae 14 3 Haliplidae 33 3 Hebridae 7 3 Mesoveliidae 9 3 Notonemouridae 33 3 Oniscigastridae 33 3 Psephenidae 14 3 Psychodidae 9 3 Pyralidae 9 3 Richardsonianidae 7 3 Thiaridae 7 3
183
5.12.4 Ecosystem Health
The Lachlan Valley river ecosystem was in Very Poor Health (Lowland and Montane Zones: Poor; Slopes and Upland Zones: Very Poor). Fish abundance was dominated by native species, but biomass was mainly alien species and most expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. The flow regime was similar to Reference Condition except for the Lachlan and Belubula downstream of Wyangala and Carcoar storages, respectively, where there were changed magnitudes of high-, low- and annual- flows and variability and seasonality.
Summary Theme assessments are as follows (Table LAC.7): Hydrology Theme • Condition Index SR–HI = 72–100 at selected mainstem locations, indicating Moderate to Good Condition (Lowland Zone: Moderate; Slopes Zone: Moderate to Good; Upland, Montane Zones: Good). • The magnitudes of high- and low-flows and annual flows were reduced in the Lowland and Slopes Zones. Mean and median annual flow volumes were reduced by 20-40 and 30- 50%, respectively. No substantial changes were apparent in the Upland and Montane Zones, or in tributaries. • Flow variability was Near Reference Condition, except for a Moderate Difference in the lower Lachlan River. • Seasonality showed a Major, declining to Moderate, Difference from Reference Condition in the Lachlan and Belubula rivers downstream of Wyangala and Carcoar Dams, respectively, but was Near Reference Condition elsewhere. Fish Theme • Condition Index SR–FI = 14 (CL 5–28), indicating Extremely Poor Condition, in the low range of scores for all Valleys. Condition differed among Zones (Lowland Zone: Poor, Slopes Zone: Extremely Poor, Upland Zone: Very Poor, Montane Zone: Poor). • Sixteen species caught, including six alien species. • Predicted native species reduced in the Lowland (62%), Slopes (89%), Upland (46%) and Montane Zones 90%. • Mean abundance 123 fish per site, mainly native species (68%). • Biomass mainly alien species (79%). Macroinvertebrate Theme • Condition Index SR–MI = 53 (CL 49–56), indicating Poor Condition (all Zones: Poor). • Moderate diversity, increasing with elevation, and low to moderate proportions of expected families in all Zones. • Moderately reduction of disturbance-sensitive families in most Zones. 184
Table LAC.7: Lachlan Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland Montane
Moderate Moderate Hydrology Condition Moderate Good Good Rating to Good to Good 14 (5–28) 1 (0–9) 29 (18–51) Fish Index 40 (13–56) 40 (12–40) Extremely Extremely Very Rating Poor Poor Poor Poor Poor
Macroinvertebrate Index 53 (49–56) 59 (56–70) 42 (30–56) 48 (43–51) 53 (50–73) Rating Poor Poor Poor Poor Poor
Ecosystem Health Very Very Very Poor Poor Rating Poor Poor Poor 185
5.13 Loddon Valley
5.13.1 Hydrology
Figure LOD.1: Loddon Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for selected sites on the Loddon mainstem were 36–83, indicating Moderate Condition (Lowland Zone: Very Poor to Moderate; Slopes Zone: Moderate to Good).
The Loddon Valley is 12,500 km2, or about 1% of the Basin area. The river flows northward from the Great Dividing Range, through Central Victoria, to join the Murray near Kerang, downstream of Torrumbarry Weir. Instream storages in the upper catchment include Cairn Curran and Tullaroop Dams and Laanecoorie Reservoir (total 228 GL). The Valley supports extensive irrigation, particularly irrigated pasture, supported by inter-valley transfers from the Murray and the Goulburn (via the Warragamba Basin). These transfers enter the Loddon at Kerang Weir and Loddon Weir, respectively. Instream weirs (Serpentine, Loddon, Boags, Kerang) provide hydraulic heads for diversions. 186
Figure LOD.1 shows values of the Hydrology Index for five selected sites and Table LOD.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams across the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). The Loddon at Site 5 was Near Reference Condition (SR–HI = 83). In the Lowland Zone (Sites 1–4), indices ranged from a Moderate Difference to a Very Large Difference from Reference Condition. The indicators show:
• High-Flow Events: Near Reference Condition at Site 5, but with a Very Large Difference from Reference Condition at Site 2, above Kerang Weir in the Lowland Zone and Moderate Difference at Sites 1,3 and 4. • Low- and Zero-Flow Events: Incidence and duration of low and zero flows, particularly in summer, exhibited Very Large to Extreme Differences from Reference Condition at most Lowland Zone sites, and Large to Very Large Differences in the Slopes Zone. • Variability: Slightly modified at most selected sites, more so at Site 2. Near Reference Condition or a Moderate Difference from Reference Condition at all sites except those near Kerang Weir. • Seasonality: Seasonality was modified at Site 4, between the major storages and diversions, but less changed at other selected sites. Near Reference Condition in the Slopes Zone but Moderate and Very Large Differences near Kerang, Loddon and Serpentine Weirs. • Gross Volume: Mean and median annual flow volumes respectively were reduced by 20% and 10–75% from Reference Condition in Slopes Zone sites, and by 10% and 45–90% in the Loddon Lowland Zone. LZFE was modified at all sites. Low-flow events are not well-protected, particularly in the lower reaches, and their incidence and duration in summer are markedly increased. The effect of regulation on seasonality is apparent at Site 4, downstream of storages but upstream of diversions. Further downstream, decreasing values for HFE and GV show the cumulative effects of diversion. Site 1, downstream of the diversion from the Murray, shows an increase in all indicator values compared to Site 2, upstream. In general, the Loddon Valley regime had highly-modified low flows, especially in the Lowland Zone where there were also major reductions in the magnitude of annual volume and high flows.
Table LOD.1: Loddon Valley: SR Hydrology Index and indicators. Sites are shown in Figure LOD.1. US: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Loddon River Outlet Lowland 65 71 29 89 70 99 2 Loddon US Kerang Weir Lowland 36 35 0 60 67 50 3 Loddon US Loddon Weir Lowland 61 69 23 88 62 82 4 Loddon US Serpentine Weir Lowland 65 70 35 91 47 79 5 Loddon at Newstead Slopes 83 99 46 96 88 94
187
5.13.2 Fish
100 Good 80 Moderate 60 Poor 40 26 Very Poor 20 12 Extremely Poor 0 0 Valley lowland slopes
Figure LOD.2: Loddon Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 188
The Loddon Valley fish community was in Extremely Poor Condition, with losses of native species, low abundance of native fish and intrusions by alien species, especially in the Slopes Zone. Nativeness varied, reflecting spatial differences in the severity of changes.
Fish communities were surveyed in two Zones of the Loddon Valley in November and December 2004. Twenty sites were sampled, yielding 659 fish. Analyses indicated an Extreme (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 12 (CL 3–27). • Over half the predicted native fish species were absent from samples. • Nativeness showed a Very Large (–) Difference from Reference Condition. • Numbers were small compared to other Valleys (average 30 fish per site). Figure LOD.2 shows sampling sites, Zones and corresponding SR–FI values, and Table LOD.2 shows Index values, Indicators, Metrics and derived variables. Ten native species were caught, including nine in Lowland sites and four in the Slopes Zone. Six alien species were recorded in the Valley, including four in each Zone. The Loddon Valley fish community showed an Extreme (+) Difference from Reference Condition (Lowland Zone: Very Large (–) Difference, Slopes Zone: Extreme (+) Difference). Only three Valleys returned lower SR Fish Index scores than the Loddon Valley (Campaspe, Goulburn, Mitta Mitta). The Lowland Zone showed a Very Large Difference from Reference Condition (SR–FI = 26). The Slopes Zone community was in Extremely Poor Condition (SR–FI = 0), reflecting the paucity of predicted native species. The confidence interval for Nativeness in Slopes Zone sites indicated great variability in the distributions of native and alien fish. In the Lowland Zone, nine of 21 predicted (RC–F) native species were collected, making up 46% of the total catch. In the Slopes Zone, only four of 14 RC–F species were recorded, although 73% of individuals were native. Native fish were 21% of the total biomass in the Lowland Zone and 14% in the Slopes Zone. Table LOD.2 shows that more RC–F native species were caught in the Lowland Zone (43%) than in the Slopes Zone (29%). There were similar numbers of fish in both Zones, but biomass was greater at Lowland Zone sites (13.7 kg/site) than at Slopes Zone sites (1.5 kg/site). Native biomass was proportionately higher in the Lowland Zone, where individual fish (Golden perch, River blackfish) averaged 212 g, compared to much smaller fish, especially Galaxias species, in the Slopes Zone (7 g). Alien fish were considerably larger, averaging 455 g across the Valley. Thus, the Lowland Zone had higher scores for Nativeness (SR–Fn = 26) and Expectedness (SR– Fe = 31) than the Slopes Zone (SR–Fn = 13, SR–Fe = 11). Carp, Brown trout and Redfin perch were the most abundant alien species. Goldfish, Eastern gambusia and Tench also were present. Table LOD.3 shows a summary of fish abundances in the Loddon Valley. Freshwater catfish were not caught, but were predicted to be common under Reference Condition. Other species not caught, but expected to be rare or moderately rare in one or both Zones under Reference Condition, included southern purple-spotted gudgeon and Freshwater catfish. 189
Few fish in the Slopes Zone showed Abnormalities, but there were more (7.5%) in the Lowland Zone. Mega-carnivore species such as Golden perch and Murray cod were absent from catches in the Slopes Zone.
Table LOD.2: Loddon Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Fish Index 12 (3–27) 26 (10–32) 0 (0–37) Expectedness Indicator 21 (19–36) 31 (23–38) 11 (11–46) Nativeness Indicator 22 (6–38) 26 (10–33) 13 (0–74) Metrics Total species 16 13 8 Native species 10 9 4 Predicted RC–F species count 22 21 14 Alien species 6 4 4 Caught/Predicted native species (%) 45 43 29 Numbers of fish Mean fish per site all species 35 30 40 Native individuals (%) 60 46 73 Fish biomass Biomass/site all species (g) 7,901 13,705 1,452 Mean native biomass/fish (g) 78 212 7 Mean alien biomass/fish (g) 455 659 114 Biomass native (%) 21 21 14
190
Table LOD.3: Loddon Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes
Australian smelt 65 1 66 Bony herring 0 0 Carp gudgeons 19 0 19 Congolli 0 0 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 44 1 45 Freshwater catfish 0 0 0 Golden perch 10 0 10 Macquarie perch 0 0 0 Mountain galaxias 0 0 Murray cod 6 0 6 Murray hardyhead 0 0 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 13 0 13 Obscure galaxias 1 187 188 River blackfish 0 71 71 Short-headed lamprey 0 0 Silver perch 3 3 Southern purple-spotted gudgeon 0 0 Southern pygmy perch 0 0 0 Trout cod 0 0 0 Un-specked hardyhead 1 1
Alien species
Brown trout 84 84 Carp 141 141 Eastern gambusia 2 2 4 Goldfish 10 10 Redfin perch 59 6 65 Tench 6 6
191
5.13.3 Macroinvertebrates
100 Good 80 Moderate 60 51 52 49 Poor 40 43 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure LOD.3: Loddon Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 192
The Loddon Valley macroinvertebrate community was in Poor Condition throughout. The fauna at most sites was impoverished and lacked disturbance-sensitive families.
Thirty four sites were surveyed across three Zones of the Loddon Valley in October 2005, yielding 9,998 macroinvertebrates in 76 families (54% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 51 (CL 45–54). • Moderate to low proportion of expected families (Filters OE = 31). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 85). SR–MI for the Loddon Valley was in the mid-range of all Valley scores (cf. Broken). All Zone communities showed a Large Difference from Reference Condition (SR–MI = 43–52), with the Slopes Zone having the lowest rating (SR–MI = 43). The wide confidence interval (26 points) for SR–MI in this Zone indicates substantial variation in condition among sites. Figure LOD.3 shows sampling sites, Zones and SR–MI values, and Table LOD.4 shows metrics and derived variables. Three quarters (75%) of expected families were recorded, although family richness was less than Reference Condition at all but three sites. Diversity was moderate (average 25 families per site), with Lowland Zone sites being least diverse (average 22 families per site). Most (82 and 78%) of the Valley fauna was in the Lowland and Slopes Zones (cf. 65% in the Upland Zone). Table LOD.5 shows that Expected (Filters OE) scores showed substantial loss of expected families. Three sites in the Lowland Zone had a high Filters OE score, and three had a low score. Filters SIGNAL OE scores were consistently low for all Zones, and a high proportion (46%) of sites in the Slopes and Upland Zones had a low score. The communities in most Slopes and Upland Zone sites were impoverished and lacking most disturbance–sensitive families. Table LOD.6 shows ‘common’ and ‘rare’ families. The 11 common families included midges (Orthocladiinae), snails (Physidae, Planorbidae), beetles (Hydrophilidae, Scirtidae) and snails (Hydrobiidae). The 16 rare families include aquatic insect families normally associated with cool, flowing waters (Hydropsychidae, Conoesucidae, Baetidae). The mayfly Tasmanophlebia (Onisci- gastridae), associated with sandy, silty, slow-flowing rivers, is rare in the Loddon. 193
Table LOD.4: Loddon Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 51 52 43 49 (45–54) (47–56) (32–58) (28–58) Metrics Filters OE 31 31 28 26 (27–33) (27–33) (22–37) (24–31) Filters SIGNAL OE 85 86 79 96 (80–89) (83–91) (72–90) (64–98) Families Families per site 25 22 29 29 minimum – maximum 12–40 12–32 13–40 24–34 Total families 76 63 60 49
Table LOD.5: Loddon Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 34 23 8 3
Filters OE High 3 3 Medium 28 18 7 3 Low 3 2 1 Filters SIGNAL OE High Medium 24 18 4 2 Low 10 5 4 1 194
Table LOD.6: Loddon Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 23 8 3 34 Number of families sampled 63 60 50 77 Percent of families in Basin 57.8 49.2 44.6 53.8 Percent of families in Valley 82 78 65 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Orthocladiinae 96 100 100 97 Hydrophilidae 83 88 67 82 Physidae 65 75 100 71 Planorbidae 48 75 67 56 Scirtidae 48 75 33 53 Paramelitidae 35 50 67 41 Glossiphoniidae 26 63 33 35 Hydrobiidae 22 63 67 35 Janiridae 30 50 33 35 Pyralidae 13 25 15 Sciomyzidae 13 33 12 Rare Ceratopogonidae 39 50 38 Baetidae 22 38 67 29 Erpobdellidae 9 6 Hydropsychidae 4 13 6 Amphipoda 13 3 Conoesucidae 33 3 Gelastocoridae 33 3 Gomphidae 13 3 Haliplidae 13 3 Hebridae 4 3 Helicopsychidae 33 3 Limnephilidae 33 3 Oniscigastridae 13 3 Phreatoicidae 33 3 Richardsonianidae 13 3 Tabanidae 4 3
195
5.13.4 Ecosystem Health
The Loddon Valley river ecosystem was in Very Poor Health (Lowland and Slopes Zones: Very Poor). Fish abundance was dominated by native species, but biomass was mainly alien species and most expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. The flow regime had modified low flows, especially in the Lowland Zone where there were also major reductions in annual volumes and high flows.
Summary Theme assessments are as follows (Table LOD.7): Hydrology Theme • Condition Index SR–HI = 36–83 at selected mainstem locations, indicating Moderate Condition (Lowland Zone: Very Poor to Moderate; Slopes Zone: Moderate to Good). • High-flow magnitudes showed Moderate Differences or were Near Reference Condition at most sites, but there was a Very Large Difference from Reference Condition in lowland reaches upstream of Kerang Weir. • Incidence and duration of low and zero flows exhibited Very Large to Extreme Differences from Reference Condition at most Lowland Zone sites, and Large to Very Large Differences in the Slopes Zone. • Flow variability was Near Reference Condition, or a Moderate Difference, at all sites except those in the vicinity of Kerang Weir. • Seasonality was Near Reference Condition in the Slopes Zone, but showed Moderate and Very Large Differences in the Loddon River near Kerang, Loddon and Serpentine Weirs. • Mean and median annual flow volumes were reduced by 20% and 10-75% from Reference Condition in Slopes Zone sites, and by 10% and 45-90% in the Lowland Zone on the Loddon River. Fish Theme • Condition Index SR–FI = 12 (CL 3–27), indicating Extremely Poor Condition (fourth lowest among all Valleys). Condition differed between Zones (Lowland Zone: Very Poor, Slopes Zone: Extremely Poor). • Sixteen species caught, including six alien species. • Predicted native species reduced in the Lowland (57%) and Slopes Zones (71%). • Mean abundance 35 fish per site, mainly native species (60%). • Biomass mainly alien species (79%). Macroinvertebrate Theme • Condition Index SR–MI = 51 (CL 45–54), indicating Poor Condition (all Zones: Poor). • Moderate diversity and low to moderate proportions of expected families in all Zones. • Disturbance-sensitive families moderately reduced in the Lowland and Upland Zones, and further reduced in the Slopes Zone. 196
Table LOD.7: Loddon Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones. An ellipsis indicates no data (a Zone not identified for this Theme)
Zone
Valley Lowland Slopes Upland
Very Poor to Moderate Hydrology Condition Moderate . . . Rating Moderate to Good 12 (3–27) 26 (10–32) 0 (0–37) Fish Index Extremely Very Extremely . . . Rating Poor Poor Poor
Macroinvertebrate Index 51 (45–54) 52 (47–56) 43 (32–58) 49 (28–58) Rating Poor Poor Poor Poor
Ecosystem Health Very Very Very . . . Rating Poor Poor Poor
197
5.14 Macquarie Valley
5.14.1 Hydrology
Figure MAC.1: Macquarie Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for selected sites on the Macquarie mainstem were 63–100, indicating Moderate to Good Condition (Lowland and Slopes Zones: Moderate Condition; Upland Zone: Good Condition).
The Macquarie River rises near Oberon, in the Central Highlands of New South Wales, and flows northwest through the Macquarie Marshes to join the Barwon River between Walgett and Brewarrina. The Macquarie system is a network of tributaries, anabranches and distributary streams. The hydrology of the lower reaches is complex, with water moving in either direction among the anabranches and the Castlereagh and Barwon, depending on relative flows. The Bogan River also flows through the Valley, joining the Darling near Bourke. Instream storages include Burrendong Dam (1,189 GL), at the junction of the Macquarie and Cudgegong rivers, Windamere Dam (361 GL) on the Cudgegong and the Ben Chifley Dam (16 GL) on the upper Macquarie. 198
Figure MAC.1 shows values of the Hydrology Index for five selected sites and Table MAC.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Sites 1–4, on the Macquarie mainstem between Burrendong Dam and the Barwon, showed a Moderate Difference from Reference Condition (SR–HI = 63–70). Site 5, on the Macquarie between Ben Chifley Dam and Burrendong Dam, was Near Reference Condition (SR–HI = 100). At Site 5, all indicators were Near Reference Condition. At other sites, the indicators show:
• High-Flow Events: All four sites showed a Moderate Difference from Reference Condition. High-flows were Near Reference Condition for all Upland and most Slopes Zone sites, but reduced by 30–55% in Lowland Zone reaches of the Bogan and Macquarie rivers and Gunningbar, Marra and Marthaguy Creeks. • Low- and Zero-Flow Events: Site 1 was Near Reference Condition; Sites 2–4 showed a Moderate Difference. • Variability: Site 1, 3 and 4 showed a Moderate Difference from Reference Condition; Site 2 was Near Reference Condition. • Seasonality: Sites 3–4 showed a Large Difference from Reference Condition; Sites 1–2 showed a Moderate Difference. • Gross Volume: Mean annual flow volumes were reduced by 5–30% from Reference Condition values in several Lowland Zone streams, by 5–25% in the Macquarie Slopes Zone and by 10–15% in the Cudgegong River. Sites 1–3 showed a Moderate Difference from Reference Condition; Site 4 was near Reference Condition. The incidence and duration of low and zero flows, variation and seasonality and volume of annual flows were Near Reference Condition for most sites, but altered with a Large to Moderate Difference from Reference Condition in several Lowland streams, the Macquarie in the Slopes Zone and the Cudgegong River. The gradual decline of GV from Site 5 downstream to Site 1 reflects diversions, despite un- regulated tributary inflows (19 of 22 tributary sites were Near Reference Condition). LZFE, V and S are altered throughout the Cudgegong River, which shows a Large Difference from Reference Condition. Data for the Macquarie at Carinda (Site 1) reflect changes to the hydrology of the Macquarie Marshes wetlands. High flows and mean and median annual flows had decreased by 25% and 40%, respectively, relative to Reference Condition. In general, the flow regime for most Macquarie Lowland Zone sites, and several Slopes and Upland Zone sites, showed reductions in the magnitude of annual and high flows, changes in low- and zero-flow events, seasonality and variability.
199
Table MAC.1: Macquarie Valley: SR Hydrology Index and indicators. Sites are shown in Figure MAC.1. DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Macquarie at Carinda Lowland 70 63 99 71 71 70 2 Macquarie at Gin Gin Slopes 67 62 63 93 65 78 3 Macquarie at Dubbo Slopes 63 77 62 75 49 77 4 Macquarie DS Burrendong Dam Slopes 64 77 64 74 41 80 5 Macquarie at Bathurst Upland 100 97 95 98 93 100
200
5.14.2 Fish
100 Good 80 Moderate 60 49 Poor 40 34 Very Poor 20 24 Extremely Poor 0 4 Valley lowland slopes upland
Figure MAC.2: Macquarie Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 201
The Macquarie Valley fish community was in Very Poor Condition, with the Upland Zone community in Extremely Poor Condition. Alien species were most of the biomass and abundance. The community had lost most of its native species and was dominated by alien fish.
Fish communities in 21 sites across three altitudinal Zones of the Macquarie Valley were surveyed in February–March 2007, yielding 7,521 fish. Analyses showed a Very Large (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 34 (CL 20–40). • Expectedness showed a Very Large (+) Difference from Reference Condition. • Nativeness showed a Very Large (+) Difference from Reference Condition. • Native species made up only 21% of the catch and 38% of total biomass. • Nine of 19 predicted native (RC–F) species were not found. Figure MAC.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MAC.2 shows Index values, Indicators, Metrics and derived variables. Ten native species and six alien species were recorded. The Valley showed a Very Large (+) Difference from Reference Condition (Lowland Zone: Large (–) Difference, Slopes Zone: Very Large (±) Difference, Upland Zone: Extreme Difference). The Macquarie Valley Fish Index was just below the average for all Valleys. Forty seven percent of the predicted (RC–F) species were not found in samples, and Expectedness and Nativeness were very low. Condition was exceptionally poor in the Upland Zone (SR–FI = 4), with a mere 2% native biomass and 51% native individuals. Lowland Zone fish were in better condition, with mid-40s scores for the Fish Index and Nativeness and Expectedness indicators. Only the Slopes and Upland Zones showed substantial variability in Condition between sites, particularly in Nativeness. Only 50%, 39% and 19% of predicted RC–F species were recorded from the Lowland, Slopes, and Upland Zones, respectively; these had three, three and six alien species, respectively. Three Slopes sites yielded only one native species. Native fish in the Upland Zone were patchily distributed, two sites had no native fish and four had only one species. Small native species including Carp gudgeons, Mountain galaxias and Bony herring often were abundant. Murray cod were caught occasionally and Freshwater catfish and Golden perch were rare. Surprisingly, only one Australian smelt was caught. Eastern gambusia were extremely abundant; Carp also were abundant and Goldfish, Redfin perch and the two trout species were common or occasional. Table MAC.3 shows that only one Golden perch and one Murray–Darling rainbowfish were caught in the Lowland Zone, where both species were predicted to occur commonly. Freshwater catfish, Macquarie perch and River blackfish were not caught at any sites in the Zones where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Silver perch, Trout cod and several small, less well-known species. Few fish (1%) showed Abnormalities; the highest incidence (5%) was in the Slopes Zone. Two Intolerant species were caught at two Upland Zone sites. Few Mega-carnivore species were found, except at Slopes Zone sites where 20 Murray cod were recorded.
202
Table MAC.2: Macquarie Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland
Fish Index 34 (20–40) 49 (33–53) 24 (8–47) 4 (0–16) Expectedness Indicator 32 (23–40) 46 (38–51) 26 (20–36) 4 (3–4) Nativeness Indicator 38 (24–46) 45 (25–57) 32 (17–63) 23 (0–44) Metric Total species 16 9 10 9 Native species 10 6 7 3 Predicted RC–S species count 19 12 18 16 Alien species 6 3 3 6 Caught/Predicted native species (%) 53 50 39 19 Numbers of fish Mean fish per site 358 104 822 148 Native individuals (%) 21 59 11 51 Fish biomass Biomass/site all species (g) 9,549 8,569 15,990 4,087 Mean native biomass/fish (g) 48 47 90 1 Mean alien biomass/fish (g) 21 134 11 55 Native individuals (%) 21 59 11 51 Biomass native (%) 38 34 50 2
203
Table MAC.3: Macquarie Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Lowland Slopes Upland Total
Australian smelt 0 1 0 1 Bony herring 332 6 338 Carp gudgeons 71 577 1 649 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 0 0 0 Freshwater catfish 0 3 1 4 Golden perch 1 3 0 4 Macquarie perch 0 0 0 Mountain galaxias 0 526 526 Murray cod 0 20 0 20 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 1 10 0 11 Olive perchlet 0 0 0 River blackfish 0 0 0 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 Spangled perch 21 0 21 Trout cod 0 0 0 Un-specked hardyhead 8 0 0 8
Alien species
Brown trout 21 21 Carp 157 77 11 245 Eastern gambusia 56 5,045 434 5,535 Goldfish 84 13 2 99 Rainbow trout 27 27 Redfin perch 12 12 204
5.14.3 Macroinvertebrates
100 Good 80 Moderate 60 52 50 49 48 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland
Figure MAC.3: Macquarie Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 205
The Macquarie Valley macroinvertebrate community was in Poor Condition. Most sites had a sparse fauna, lacking most of their expected disturbance–sensitive families.
Thirty five sites were surveyed across three Zones of the Macquarie Valley in October 2005, yielding 9,863 macroinvertebrates in 72 families (51% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 50 (CL 46–54). • A moderate to low proportion of expected families (Filters OE = 28). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 90). SR–MI for the Macquarie Valley was in the mid-range of scores for all Valleys (cf. Loddon, Broken). All Zone communities showed a Large Difference from Reference Condition (SR–MI = 48–52), with moderate variation in condition among sites. Figure MAC.3 shows sampling sites, Zones and SR–MI values, and Table MAC.4 shows metrics and derived variables. Seventy percent of expected families were recorded in the Valley, although family richness was less than Reference Condition at 94% of sites. Diversity was moderate (average 22 families per site), with Lowland Zone sites being least diverse (average 17 families per site). Most (87%) of the Valley fauna was in the Upland Zone (cf. 60–66% for Lowland and Slopes Zones). Expected (Filters OE) scores indicated substantial loss of expected families in all Zones. No site in the Valley had a high Filters OE score, and two had a low score. Filters SIGNAL OE scores were consistently low for all Zones, at 88–94% of sites in the three Zones. Most sites in all Zones had sparse communities lacking most disturbance-sensitive families (Table MAC.5). Table MAC.6 shows ‘common’ and ‘rare’ families. Eight common families included midges and mosquitoes (Chironominae, Tanypodinae, Ceratopogonidae, Culicidae), damselflies (Lestidae) and aquatic leeches (Richardsonianidae). These are common families of still and slow-flowing waters. The 16 rare families included aquatic insect families associated with faster flowing, cooler waters (for example, the mayfly Coloburiscoides (Coloburiscidae) is rare in the Macquarie owing to the lack of these habitats). 206
Table MAC.4: Macquarie Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland
Index SR–MI 50 52 49 48 (46–54) (45–56) (39–58) (41–55) Metrics Filters OE 28 29 27 27 (26–30) (25–33) (22–33) (26–32) Filters SIGNAL OE 90 91 93 90 (85–94) (86–94) (79–97) (78–94) Families Families per site 22 17 20 31 minimum – maximum 9–42 9–20 15–33 25–42 Total families 72 42 48 63
Table MAC.5: Macquarie Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland
Number of sites 35 17 8 10
Filters OE High Medium 33 16 7 10 Low 2 1 1 Filters SIGNAL OE High 3 1 1 1 Medium 27 16 5 6 Low 5 2 3 207
Table MAC.6: Macquarie Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 17 8 10 35 Number of families sampled 46 51 67 77 Percent of families in Basin 40.0 38.9 57.3 50.7 Percent of families in Valley 60 66 87 100
Percent of sites by Zone Lowland Slopes Upland VALLEY
Common Chironominae 100 100 100 100 Notonectidae 94 88 100 94 Tanypodinae 100 88 90 94 Ceratopogonidae 76 75 100 83 Culicidae 76 50 40 60 Lestidae 29 25 20 26 Gordiidae 20 6 Richardsonianidae 6 10 6 Rare Calamoceratidae 20 6 Staphylinidae 12 6 Ceinidae 10 3 Coloburiscidae 10 3 Conoesucidae 10 3 Corbiculidae 13 3 Diamesinae 10 3 Dixidae 10 3 Ephydridae 6 3 Haliplidae 6 3 Helicopsychidae 10 3 Odontoceridae 10 3 Philopotamidae 10 3 Pyralidae 10 3 Sciomyzidae 10 3 Sialidae 10 3
208
5.14.4 Ecosystem Health
The Macquarie Valley river ecosystem was in Very Poor Health (Lowland Zone: Poor; Slopes and Upland Zones: Very Poor). Fish abundance and biomass were dominated by alien species, and many expected fish species were absent. Many expected and disturbance-sensitive macro- invertebrate families were absent. The flow regime for most Lowland, and several Slopes and Upland reaches was typified by reductions in magnitude of annual and high flows, changes in low and zero flow events, flow seasonality and variability.
Summary Theme assessments are as follows (Table MAC.7): Hydrology Theme • Condition Index SR–HI = 63–100 at selected mainstem locations, indicating Moderate to Good Condition (Lowland, Slopes Zones: Moderate; Upland Zone: Good). • High-flow magnitudes were Near Reference Condition for all Upland and most Slopes Zone sites, but reduced by 30–55% at most Lowland Zone sites. • Incidence and duration of low and zero flows, flow variability and seasonality and volume of annual flows were Near Reference Condition at most sites, but showed a Large to Moderate Difference from Reference Condition in several lowland tributaries, the Macquarie Slopes Zone and an upland tributary, the Cudgegong River. • Mean annual flow volumes were reduced from Reference Condition values by 5–30% in several Lowland streams, 5-25% in the Macquarie River in the Slopes Zone and 10–15% in the Cudgegong River. Fish Theme • Condition Index SR–FI = 34 (CL 20–40), indicating Very Poor Condition, near the average score for all Valleys. Condition differed among Zones (Lowland Zone: Poor, Slopes Zone: Very Poor, Upland Zone: Extremely Poor). • Sixteen species caught, including six alien species. • Predicted native species reduced in the Lowland (50%), Slopes (61%) and Upland Zones (81%). • Mean abundance 358 fish per site, mainly alien species (79%). • Biomass mainly alien species (61%). Macroinvertebrate Theme • Condition Index SR–MI = 50 (CL 46–54), indicating Poor Condition (all Zones: Poor). • Diversity moderate in all Zones, but low in the Upland Zone. • Moderate to low proportions of expected families in all Zones. • Some reduction of disturbance-sensitive families in all Zones. 209
Table MAC.7: Macquarie Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland
Moderate Hydrology Condition Moderate Moderate Good Rating to Good 34 (20–40) 24 (8–47) 4 (0–16) Fish Index 49 (33–53) Very Very Extremely Rating Poor Poor Poor Poor
Macroinvertebrate Index 50 (46–54) 52 (45–56) 49 (39–58) 48 (41–55) Rating Poor Poor Poor Poor
Ecosystem Health Very Very Very Poor Rating Poor Poor Poor
210
5.15 Mitta Mitta Valley
5.15.1 Hydrology
Figure MIT.1: Mitta Mitta Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Mitta Mitta mainstem were 78–100, and those for tributaries were 85–100, indicating Good Condition (Slopes Zone: Moderate to Good Condition; Upland Zone: Good Condition.
The Mitta Mitta River rises in the Great Dividing Range east of Falls Greek township, near the Kiewa headwaters, where four tributaries (Big, Bundara and Cobungra rivers, Livingstone Creek) join. The river flows northwest to meet the Murray via the south arm of Lake Hume. Tallangatta Creek, formerly a tributary to the Mitta Mitta, now enters Lake Hume nearby. Other tributaries to the Mitta Mitta Slopes Zone are Snowy Creek and Little Snowy Creek, both rising at Mount Bogong. The Mitta Mitta Valley is narrow and steep for most of its length, forming a floodplain only as it approaches Lake Hume. The largest instream storage in the Basin, Lake Dartmouth 211
(3,900 GL), is at the junction of the Mitta Mitta Slopes and Upland Zones. Originally intended as a drought reserve, long periods of low rainfall and increased irrigation demand have resulted in substantial releases in most years since its construction in 1979. Figure MIT.1 shows values of the Hydrology Index for five selected sites and Table MIT.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Sites 1, 2, 4 and 5 were Near Reference Condition (SR–HI = 88–100). Site 3, downstream of Dartmouth Dam, showed a Moderate Difference from Reference Condition (SR–HI = 78). The indicators show:
• High-Flow Events: Near Reference Condition, except immediately downstream of Dartmouth Dam. Site 3 showed a Moderate Difference from Reference Condition. • Low- and Zero-Flow Events: Near Reference Condition, except in the Mitta Mitta immediately upstream of Hume Reservoir and in one upper Zone tributary. Site 1 showed a Moderate Difference from Reference Condition; other sites were Near Reference Condition. • Variability: All sites were Near Reference Condition. • Seasonality: Near Reference Condition, except immediately downstream of Dartmouth Dam. Site 3, downstream of Dartmouth Dam, showed a Large Difference from Reference Condition and Sites 1–2 showed a Moderate Difference. • Gross Volume: Near Reference Condition, except just downstream of Dartmouth Dam. Little water is diverted from the Mitta Mitta, so that GV is Near Reference Condition over the length of the river. Storage of winter-spring flows has changed Seasonality at Site 3, downstream of Dartmouth Dam, reduced high-flow events and changed the duration and magnitude of low flows. Apart from hydrological changes, releases from Dartmouth Dam depress temperatures in the Mitta Mitta downstream, and threaten native fish populations. In general, most sites on the Mitta Mitta River showed little difference from Reference Condition and all indicators in tributaries and upstream of Dartmouth Dam are Near Reference Condition. Downstream of the dam, there were changes in seasonality and high- and low-flow events.
Table MIT.1: Mitta Mitta Valley: SR Hydrology Index and indicators. Sites are shown in Figure MIT.1. US: upstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Mitta Mitta US Hume Dam Slopes 88 84 74 88 64 97 2 Mitta Mitta at Tallandoon Slopes 97 91 91 91 61 100 3 Mitta Mitta at Coleman Gauge Slopes 78 69 82 87 44 83 4 Mitta Mitta US Dartmouth Dam Upland 100 100 100 100 95 100 5 Mitta Mitta US Livingstone Ck Upland 100 99 100 100 100 100
212
5.15.2 Fish
100 Good 80 Moderate 60 Poor 40 Very Poor 20 20 21 10 13 Extremely Poor 0 Valley slopes upland montane
Figure MIT.2: Mitta Mitta Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 213
The Mitta Mitta Valley fish community was in Extremely Poor Condition. Alien species were 92% of total biomass and 50% of total abundance. The community had lost most of its native species richness and was dominated by alien fish.
Fish communities of three altitudinal Zones in the Mitta Mitta Valley were surveyed in January– February 2005. The 21 sampling sites yielded a catch of 717 fish. Analyses showed an Extreme (+) Difference from Reference Condition: • SR Fish Index (SR–FI) = 10 (CL 3–39). • Expectedness showed an Extreme (+) Difference from Reference Condition. • Nativeness showed Very Large (±) Difference from Reference Condition. • Average numbers of fish were low (34 per site) and the percentage of total biomass that was native (8%) was extremely low. Figure MIT.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MIT.2 shows Index values, Indicators, Metrics and derived variables. Only 43%, 22% and 50% of predicted (RC–F) native fish were recorded from the Slopes, Upland and Montane Zones, respectively. These Zones had six, three and one alien species, respectively. The Mitta Mitta Valley showed an Extreme (+) Difference from Reference Condition (Slopes Zone: Very Large (±) Difference, Upland Zone: Very Large (–) Difference, Montane Zone: Extreme (+) Difference). The Fish Index score was the third lowest for the Basin. Across the Valley, only 43% of the predicted native species were caught. Variation in the Nativeness Indicator was high. Throughout the three Zones, the number of native species observed was never more than half of those predicted under Reference Conditions (43%, 22% and 50%, respectively), with an overall 43% of predicted species found in the Valley. Small numbers of fish (average 34 fish per site) were collected, compared with other Valleys. Total fish biomass also was lower than most other Valleys and the proportion of fish biomass contributed by native species was extremely low, at 8% for the Valley as a whole. Alien Brown trout dominate the fauna of the Mitta Mitta Valley and there are substantial numbers of Rainbow trout, Carp and Redfin perch. Eastern gambusia and Goldfish occur sparsely. Dominant native fish include the two blackfish species, Flat-headed gudgeon and Mountain galaxias. Dartmouth Dam causes severe cold-water pollution in mainstem Slopes Zone sites, but does not directly affect tributaries. Depressed temperatures favour trout over native fish. Trout also dominated Montane Zone sites, where there were few native fish. Communities at cold–polluted sites were in Extremely Poor Condition, with only one native species at any site and up to five alien species. Alien species in the Slopes Zone had high average biomass per fish (539 g) compared to the smaller native fish (15 g). Table MIT.3 shows a summary of native species abundances. Riffle galaxias and Macquarie perch were not caught at any sites in the Zones where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Golden perch, Macquarie perch, Murray cod, Trout cod, River blackfish and some smaller, less well-known species. Mega-carnivore species were conspicuously absent from catches, but very few fish showed Abnormalities. Several Intolerant species were recorded. 214
Table MIT.2: Mitta Mitta Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Slopes Upland Montane Fish Index 10 (3–39) 20 (8–41) 21 (4–36) 13 (13–47) Expectedness Indicator 18 (18–37) 24 (24–35) 15 (15–15) 30 (30–57) Nativeness Indicator 24 (10–51) 26 (8–70) 50 (19–75) 0 (0–45) Metric Total species 12 12 5 3 Native species 6 6 2 2 Predicted RC–F species count 14 14 9 4 Alien species 6 6 3 1 Caught/Predicted native species (%) 43 43 22 50 Numbers of fish Mean fish per site 34 41 31 31 Native individuals (%) 50 66 57 20 Fish biomass Biomass/site all species (g) 3,263 7,923 1,060 805 Mean native biomass/fish (g) 15 14 14 18 Mean alien biomass/fish (g) 175 539 62 28 Biomass native (%) 8 5 23 14
215
Table MIT.3: Mitta Mitta Valley: numbers of native fish by Zone. Predicted species (RC–F list) are shown by numbers; species not predicted are shown by blanks
Native species Zone Total Slopes Upland Montane
Australian smelt 0 0 0 Carp gudgeons 0 0 Flat-headed gudgeon 41 0 41 Riffle galaxias 0 0 0 0 Golden perch 0 0 Macquarie perch 0 0 0 0 Mountain galaxias 30 31 22 83 Murray cod 0 0 0 Flat-headed galaxias 0 0 Obscure galaxias 14 14 River blackfish 63 0 63 Southern pygmy perch 11 11 Trout cod 0 0 0 Two–spined blackfish 28 93 22 143
Alien species
Brown trout 53 53 172 278 Carp 26 1 27 Eastern gambusia 3 3 Goldfish 1 1 Rainbow trout 5 38 43 Redfin perch 10 10 216
5.15.3 Macroinvertebrates
100 Good 80 Moderate 60 59 63 55 57 Poor 40 Very Poor 20 Extremely Poor 0 Valley slopes upland montane
Figure MIT.3: Mitta Mitta Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median
217
The Mitta Mitta Valley macroinvertebrate community was in Poor Condition throughout. Most sites had an impoverished fauna, although they retained most disturbance–sensitive families.
Thirty two sites were surveyed across three Zones of the Mitta Mitta Valley in November 2005, yielding 10,535 macroinvertebrates in 82 families (57% of Basin families). Analyses showed a Large (+) Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 59 (CL 51–65). • Moderate to low proportion of expected families (Filters OE = 29). • SIGNAL OE score near Reference Condition (Filters SIGNAL OE = 104). SR–MI for the Mitta Mitta Valley was the equal fourth highest score of all Valleys (equal to that for the Kiewa Valley). The Slopes and Montane Zone communities each showed a Large (+) Difference from Reference Condition (SR–MI = 55, 57 respectively), and the Upland Zone a Moderate (–) Difference (SR–MI = 63). The wide confidence interval for SR–MI in the Upland Zone (24 points) indicated substantial variation among sites. Figure MIT.3 shows sampling sites, Zones and SR–MI values, and Table MIT.4 shows metrics and derived variables. Eighty percent of expected families were recorded in the Valley, and family richness was less than Reference Condition at all sites bar one (97% of stream length). Diversity was moderate to high (average 29 families per site), with Slopes Zone sites being most diverse (average 30 families per site). Most (83%) of the Valley fauna was in the Upland Zone (cf. 69 and 70% for the Slopes and Montane Zones). Table MIT.5 shows that Expected (Filters OE) scores indicated moderate to substantial loss of expected families. No sites in the Valley had a high Filters OE score. Filters SIGNAL OE scores were generally high low for the Slopes and Upland Zones, with a high proportion (58% and 82%, respectively) of sites in these Zones having a high Filters SIGNAL OE score. Most Slopes and Upland Zones had impoverished faunas but had retained most disturbance–sensitive families. The entire stream length has macroinvertebrate communities with significant loss of expected families, but 66% of stream length has a good Filters SIGNAL OE score. Changes in the Mitta Mitta Valley are not causing major losses of disturbance– or pollution–sensitive families. Table MIT.6 shows ‘common’ and ‘rare’ families. The 18 common families included 14 insect families (e.g. mayflies, stoneflies, caddisflies, beetles, dragonflies) typical of cool, fast–flowing water. Many of the 24 ‘rare’ families favour slow–flowing water. 218
Table MIT.4: Mitta Mitta Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Slopes Upland Montane
Index SR–MI 59 55 63 57 (51–65) (41–70) (46–70) (53–67) Metrics Filters OE 29 27 31 28 (26–32) (20–35) (24–32) (26–33) Filters SIGNAL OE 104 104 104 104 (96–110) (92–116) (86–117) (102–107) Families Families per site 29 30 29 28 minimum – maximum 19–39 20–39 23–38 19–36 Total families 82 58 69 59
Table MIT.5: Mitta Mitta Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Slopes Upland Montane
Number of sites 32 9 12 11
Filters OE High Medium 31 8 12 11 Low 1 1 Filters SIGNAL OE High 21 5 7 9 Medium 9 4 3 2 Low 2 2 219
Table MIT.6: Mitta Mitta Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 9 12 11 32 Number of families sampled 59 71 60 86 Percent of families in Basin 45.0 60.7 57.1 56.6 Percent of families in Valley 69 83 70 100
Percent of sites by Zone Slopes Upland Montane VALLEY
Common Orthocladiinae 100 100 100 100 Baetidae 89 100 100 97 Gripopterygidae 89 92 100 94 Simuliidae 78 100 82 88 Conoesucidae 89 75 91 84 Tipulidae 100 58 91 81 Coloburiscidae 89 67 82 78 Elmidae 56 67 100 75 Oniscigastridae 33 75 100 72 Aeshnidae 89 67 36 63 Philorheithridae 44 58 73 59 Psephenidae 56 33 91 59 Corydalidae 44 33 36 38 Helicopsychidae 22 33 27 28 Notonemouridae 42 27 25 Ptilodactylidae 25 27 19 Neoniphargidae 17 18 13 Nevrothidae 25 9 Rare Tanypodinae 56 75 64 66 Hydrophilidae 44 58 27 44 Hydraenidae 25 27 19 Physidae 56 8 19 Ancylidae 11 25 13 Gyrinidae 11 17 9 Parastacidae 11 17 9 Culicidae 11 8 6 Hydrometridae 22 6 Ameletopsidae 9 3 Aphroteniinae 8 3 Blephariceridae 11 3 Eusiridae 9 3 Gelastocoridae 8 3 Hirudinea 8 3 Isopoda 9 3 Naucoridae 11 3 Podonominae 9 3 Polycentropodidae 9 3 Richardsonianidae 8 3 Tabanidae 9 3 Tanyderidae 11 3 Temnocephalidea 9 3 Thaumaleidae 8 3 220
5.15.4 Ecosystem Health
The Mitta Mitta Valley river ecosystem was in Very Poor Health (Slopes and Montane Zones: Very Poor; Upland Zone: Poor). Fish abundance and biomass were dominated by alien species, and most expected species were absent. Many expected and several disturbance-sensitive macro- invertebrate families were absent. The flow regime is little changed from Reference Condition, apart from changes in seasonality and high- and low-flows below Dartmouth Dam.
Summary Theme assessments are as follows (Table MIT.7): Hydrology Theme • Condition Index SR–HI = 78–100 at selected mainstem locations and 85–100 for tributaries, indicating Good Condition (Slopes Zone: Moderate to Good; Upland Zone: Good). • High flow magnitudes Near Reference Condition, except immediately downstream of Dartmouth Dam. • Incidence and duration of low and zero flows Near Reference Condition, except in the Mitta Mitta upstream of Lake Hume and in Days Creek, an upper Zone tributary. • Flow variability was Near Reference Condition throughout. • Seasonality of flows was Near Reference Condition, except immediately downstream of Dartmouth Dam. • Annual flow volume was Near Reference Condition, except immediately downstream of Dartmouth Dam. Fish Theme • Condition Index SR–FI = 10 (CL 3–39), indicating Extremely Poor Condition, the third lowest score for all Valleys. Condition varied among Zones (Slopes and Upland Zones; Very Poor, Montane Zones: Extremely Poor). • Twelve species caught, including six alien species. • Predicted native species reduced in the Slopes (57%), Upland (78%) and Montane Zones (50%). • Mean abundance 34 fish per site, equally native and alien species. • Biomass overwhelmingly alien species (92%). Macroinvertebrate Theme • Condition Index SR–MI = 59 (CL 51–65), indicating Poor Condition (Upland Zone: Moderate Condition; Other Zones: Poor Condition). • Moderate to high diversity but low proportions of expected families in all Zones. • High proportion of expected disturbance-sensitive families in all Zones. 221
Table MIT.7: Mitta Mitta Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Slopes Upland Montane
Moderate Hydrology Condition Good Good Good Rating to Good 10 (3–39) 20 (8–41) 21 (4–36) 13 (13–47) Fish Index Extremely Very Very Extremely Rating Poor Poor Poor Poor
Macroinvertebrate Index 59 (51–65) 55 (41–70) 63 (46–70) 57 (53–67) Rating Poor Poor Moderate Poor
Ecosystem Health Very Very Very Poor Rating Poor Poor Poor
222
5.16 Murray Valley, Lower
5.16.1 Hydrology
Figure MVL.1: Lower Murray Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Condition of the Lower Murray was Poor throughout, with Hydrology Index scores of 50–60.
The Lower Murray Valley begins at Lock 10, below the Murray-Darling confluence, and ends with the Murray’s entry to Lake Alexandrina, hence Lake Albert and the Coorong, isolated from the Southern Ocean by barrages that prevent incursions by sea water. It also includes the tributaries of the Mt Lofty Zone, draining the eastern slopes of the Mt Lofty Ranges. The Murray flows westward through a broad floodplain from Wentworth to Morgan, where the river turns southward through a limestone gorge extending to about Mannum. The lowermost reaches are flanked by former swamplands, now reclaimed for agriculture by earthen levees. There are Ramsar-listed wetlands at Chowilla, near Renmark, and the Lower Lakes and Coorong. 223
Flows are highly modified by diversions, regulation and inter-valley transfers upstream. There are no major instream storages, but a series of nine low-level weirs that has had profound effects on the river and its floodplain (e.g. Walker 2006). An offstream storage, Lake Victoria (677 GL), regulates flows from the Murray and Darling to meet downstream demand from major irrigation areas, from Adelaide and rural towns and cities in South Australia. The river-mouth barrages maintain high water levels (and low salinity) in the Lower Lakes, supporting local irrigation. Reduced flows over the barrages, intensified by the prevailing drought, have caused major changes to the Coorong. Figure MVL.1 shows values of the Hydrology Index for five selected sites and Table MVL.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). No modelled data were available for the small tributaries of the Mt Lofty Zone. All five selected sites showed a Large to Moderate Difference from Reference Condition (SR–HI = 50–60). The indicators show:
• High-Flow Events: All sites showed a Very Large Difference from Reference Condition, with reductions in high-flow magnitudes of 69–88%, 66% and 68–69% in the Upper, Middle and Lower Zones, respectively. • Low- and Zero-Flow Events: The Lower Murray showed little change in the duration of zero-flows, but there was a substantial increase in the frequency of low flows, particularly in winter-spring, changing the magnitude of low flows by 45–58% over all three Zones. Site 1, 4 and 5 showed a Moderate Difference from Reference Condition; Sites 2–3 were Near Reference Condition. • Variability: All sites showed a 31–40% decline in Variability (thus, a Moderate Difference from Reference Condition). Although the magnitude of extreme flow events was similar for modelled current and natural regimes, regulation and diversions mean that flows in excess of demand are fewer and the distribution of flows is skewed towards low volumes. • Seasonality: All sites showed a Moderate Difference from Reference Condition. • Gross Volume: Current mean annual volumes are reduced by about 50% from Reference Condition values, and median annual volumes are reduced by 60–70%. All sites showed a Very Large Difference from Reference Condition. The Lower Murray regime shows the effects of major diversions, indicated by GV and HFE. Modelled current annual flows are half of ‘natural’ annual flows, and median annual flows are reduced by two-thirds, indicating a major shortfall for over half the time. Seasonality is less- modified in the Lower Murray Valley than in the Central Murray Valley (Section 5.17.1), because un-seasonal high flows are maintained for irrigation in summer. In general, the Lower Murray regime is modified by long-term reductions in the magnitudes of mean and median annual flows and high-flow events by about a half, a third and two- thirds, respectively. There are also reductions in Variability and Seasonality.
224
Table MVL .1: Lower Murray Valley: SR Hydrology Index and indicators. Sites are shown in Figure MVL .1. US: upstream; DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Murray at Wellington Lower 56 31 79 61 60 31 2 Murray at Morgan Middle 60 33 83 64 66 35 3 Murray DS Lock 3 Upper 60 31 85 66 65 37 4 Murray US Lock 7 Upper 50 23 75 63 68 34 5 Murray US Lock 9 Upper 50 24 75 63 70 34
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5.16.2 Fish
100 Good 80 Moderate 60 58 55 53 50 Poor 40 42 Very Poor 20 Extremely Poor 0 Valley lower middle upper Mt Lofty
Figure MVL.2: Lower Murray Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 226
The Lower Murray Valley fish community was in Poor Condition. Only 40% of predicted native species were caught, although Nativeness was increased by the abundance of native fish. The Mt Lofty Zone was drought–affected, and the community there was different from those in the weir– pool habitats of the Murray. Thirteen predicted species that require access to the estuary were missing, due to the barrier effect of the barrages. The community had lost much of its native species richness and its biomass was dominated by alien fish.
Twenty two sites in the Lower Murray Valley were surveyed in April and May 2005, and a further six sites sampled in June. A total of 6,128 fish was caught. Analyses indicated a Large Difference from Reference Condition: • SR Fish Index (SR–FI) = 53 (CL 49–58). • Expectedness showed a Large Difference from Reference Condition. • Nativeness showed a Moderate (–) Difference from Reference Condition. Figure MVL.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MVL.2 shows Index values, Indicators, Metrics and derived variables. The Lower Murray Valley community showed a Large Difference from Reference Condition (Lower and Upper Zones: Large Difference, Middle: Large (+) Difference). The Mt Lofty Zone community showed a Large (–) Difference from Reference Condition. Three Zones are designated in the Murray River and an additional Zone covers the Mt Lofty catchment. The Lower, Middle, and Upper Zones do not represent marked altitudinal differences or large biogeographical differences, but they are subject to management–related, biological and geomorphic differences. In the Lower Zone, the floodplain is isolated by levees, although there are no weirs, there are large terminal lakes and barrages that block estuarine connections. Weir- pools are dominant habitats in the Upper and Middle Zones, flanked in most areas by overhanging willows (Salicaceae). The river in the Middle Zone is deep (up to 30 m) with a narrow, constrained floodplain. In the Upper Zone, the floodplain is unconstrained and wide, and there are many wetlands. The Mt Lofty Zone includes a number of small tributaries. Only 31%, 38% and 35% of predicted (RC–F) native fish were recorded from the Lower, Middle and Upper Zones, respectively. Only six of 16 RC–F species were recorded in the Mt Lofty Zone, with four alien species, so that there was low Expectedness (SR–Fe =41) and moderate Nativeness (SR–Fn = 66). Low index scores in the Mt Lofty Zone may have been influenced by the drought, which restricted the number of sites suitable for sampling. Variability was very low among indices for the three Murray Zones, indicating that their communities are in similar condition. In the Mt Lofty Zone, variability was greater, with substantial variation among sites. Site-selection was delayed into autumn-winter in the Lower Murray, and falling water temperatures and short day-length may have influenced catches. In particular, it is likely that Carp were under-represented because their wintering behaviour reduces catchability (Dr Qifeng Ye, SARDI, pers. comm.). As a result, condition indices may have been overestimated in the Lower Murray Zones. Table MVL.3 shows a summary of native species. Thirteen RC–F species that require unobstructed passage to the estuary to sustain their populations were missing from SRA catches, presumably because of the barrier effect of the barrages. Strictly riverine fishes including Silver perch, Murray cod and Freshwater catfish were not caught in Zones where they were expected to 227 be common under Reference Condition. Other species not caught, but predicted to be occasionally or rare caught in one or more Zones under Reference Condition, are also listed. Fish were numerous (average 219 per site). Abundant Bony herring, Un-specked hardyhead, Mountain galaxias, Australian smelt, Southern pygmy perch, Murray–Darling rainbowfish and Murray-Darling carp gudgeon dominated the native fish, and Eastern gambusia and Carp dominated the alien species. Goldfish and Redfin perch also were common, and Rainbow trout and Brown trout occurred occasionally, especially in the Mt Lofty Zone. Few Abnormalities on fish were recorded. No Intolerant species were caught in the Murray Zones. Mega-carnivore species were not recorded from the Mt Lofty Zone.
Table MVL.2: Lower Murray Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Zone Valley Lower Middle Upper Mt Lofty
Fish Index 53 (49–58) 50 (41–53) 58 (54–63) 55 (49–59) 42 (27–59) Expectedness Indicator 41 (41–43) 34 (32–37) 45 (45–45) 42 (42–42) 39 (39–47) Nativeness Indicator 66 (55–74) 70 (56–80) 71 (62–81) 68 (56–77) 43 (17–73) Metrics Total species 20 14 13 11 10 Native species 14 10 9 8 6 Predicted RC–F species count 35 32 24 23 16 Alien species 6 4 4 3 4 Caught/Predicted native species (%) 40 31 38 35 38 Numbers of fish Mean fish per site 219 179 304 225 167 Native individuals (%) 90 96 93 96 71 Fish biomass Biomass/site all species (g) 12,265 8,023 24,034 15,540 1,463 Mean native biomass/fish (g) 24 18 36 26 4 Mean alien biomass/fish (g) 344 699 655 996 21 Biomass native (%) 39 39 42 36 29
228
Table MVL.3: Lower Murray Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks. Asterisks denote species requiring unobstructed passage to the estuary
Zone Total Native species Lower Middle Mt Lofty Upper
Australian smelt 173 206 0 173 552 Black bream * 0 0 Blue spot goby * 0 0 Bony herring 799 1,020 383 2,202 Carp gudgeons 3 197 0 86 286 Climbing galaxias * 0 0 Common galaxias * 14 0 8 22 Congolli * 0 0 0 0 0 Dwarf flat-headed gudgeon 1 2 1 0 4 Estuary perch * 0 0 0 Flat-headed galaxias 0 0 0 0 Flat-headed gudgeon 48 34 38 30 150 Freshwater catfish 1 1 0 2 Golden perch 15 71 0 45 131 Lagoon goby * 0 0 Macquarie perch 0 0 Mountain galaxias 402 402 Murray cod 0 0 0 0 0 Murray hardyhead 0 0 1 1 Murray–Darling rainbowfish 71 84 157 312 Obscure galaxias * 0 18 18 Olive perchlet 0 0 0 0 Pouched lamprey * 0 0 0 0 0 River blackfish 0 0 0 0 0 Sandy sprat * 0 0 Short–finned eel * 0 0 0 0 0 Short-headed lamprey * 0 0 0 0 0 Silver perch 0 0 0 0 Small-mouthed hardyhead * 0 0 Southern purple-spotted gudgeon 0 0 0 0 Southern pygmy perch 0 0 366 0 366 Trout cod 0 0 0 0 Un-specked hardyhead 78 364 632 1,074 Yarra pygmy perch 0 0 Yellow-eyed mullet * 0 0
Alien species
Brown trout 7 7 Carp 39 103 58 200 Eastern gambusia 2 9 292 5 308 Goldfish 2 31 7 40 Rainbow trout 3 3 Redfin perch 6 5 37 48 See Section 6.3.1 for discussion of representation in samples of particular species 229
5.16.3 Macroinvertebrates
100 Good 80 Moderate 60 56 55 48 Poor 40 39 31 Very Poor 20 Extremely Poor 0 Valley lower middle upper Mt Lofty
Figure MVL.3: Lower Murray Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 230
The Lower Murray Valley macroinvertebrate community was in Poor Condition, with the Lower and Middle Zones in Very Poor Condition, and the Upper and Mt Lofty Zones in Poor Condition. Most sites had impoverished faunas, but retained many of their disturbance-sensitive families.
Thirty three sites were surveyed across three Zones of the Lower Murray Valley in May 2006, yielding 4,291 macroinvertebrates in 58 families (47% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 48 (CL 47–56). • Moderate proportion of expected families (Filters OE = 25). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 97). SR–MI for the Lower Murray Valley had the equal sixth-lowest score for all Valleys (cf. Murrumbidgee). The Lower and Middle Zone communities showed Very Large (+) Differences from Reference Condition (SR–MI = 31, 39 respectively) and the Upper and Mt Lofty Zones showed Large (+) Differences (SR–MI = 56, 55 respectively). Wide confidence intervals for SR– MI in the Mt Lofty Zone (23 points) indicated substantial variation in condition among sites. Figure MVL.3 shows sampling sites, Zones and SR–MI values, and Table MVL.4 shows metrics and derived variables. Most (82%) of the expected families were recorded in the Valley, although family richness was less than Reference Condition at all sites except one (98% of sites). Diversity was moderate to low (average 18 families per site), with Mt Lofty Zone sites being most diverse (average 22 families per site) and Murray sites having consistently lower diversity (average 16 families per site). Most (82%) of the Valley fauna occurred in the Mt Lofty Zone, and only 36 and 45% of the Valley fauna occurred in the Lower and Middle Zones of the Murray. The Upper Zone was more diverse (47 families, or 70% of the Valley total). Table MVL.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Only one site in the Valley had a high Filters OE score, and five sites (10% of stream length) had a low Filters OE score. Filters SIGNAL OE scores were slightly reduced or near Reference Condition in all Zones, with a high proportion (67%) of sites in the Murray having a high Filters SIGNAL OE score but reduced Filters OE score. The Murray sites generally had impoverished communities, but retained most disturbance–sensitive families. In contrast, the Mt Lofty Zone community was impoverished and most sites were missing disturbance-sensitive families. Table MVL.6 shows ‘common’ and ‘rare’ families. The 15 common families included several common in all Zones, namely shrimp (Atyidae) mites (Acarina), worms and midges, as well as caenid mayflies, hydroptilid caddisflies and little basket shells (Corbiculidae). These are generally associated with silty, still–water habitats and/or arid–zone intermittent streams. Six families were very common in both the Upper Zone of the Murray and Mt Lofty Zone sites, but less frequent in the Middle and Lower Zones of the Murray. These were: nemertean worms, aquatic moths (Pyralidae), brine flies and moth flies (Ephydridae, Psychodidae) and velvet water bugs (Hebridae). All are typical of slightly saline water.
231
Table MVL.4: Lower Murray Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lower Middle Upper Mt Lofty
Index SR–MI 48 31 39 56 55 (47–56) (23–41) (29–42) (48–62) (44–67) Metrics Filters OE 25 18 21 28 32 (25–29) (14–22) (17–22) (24–31) (27–34) SIGNAL 97 94 95 103 89 (90–103) (92–95) (94–100) (97–103) (71–111) Families Families per site 18 16 14 18 22 minimum – maximum 9–27 12–19 10–17 9–26 18–27 n families 58 21 25 43 48
Table MVL.5: Lower Murray Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lower Middle Upper Mt Lofty
Number of sites 33 2 7 16 8
Filters OE High 1 1 Medium 27 1 4 14 8 Low 5 1 3 1 Filters SIGNAL OE High 12 1 9 2 Medium 19 2 6 7 4 Low 2 2
232
Table MVL.6: Lower Murray Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 2 7 16 8 33 Number of families sampled 24 30 47 55 67 Percent of families in Basin 22.0 27.5 43.1 45.1 46.9 Percent of families in Valley 36 45 70 82 100
Percent of sites by Zone Lower Middle Upper Mt Lofty VALLEY
Common Chironominae 100 100 100 100 100 Oligochaeta 100 100 100 100 100 Orthocladiinae 100 100 100 88 97 Acarina 100 100 88 75 88 Atyidae 100 100 94 50 85 Caenidae 100 100 88 50 82 Hydroptilidae 50 71 88 75 79 Corbiculidae 50 71 63 13 52 Corallanidae 43 50 33 Nemertea 14 31 13 21 Psychodidae 38 13 21 Lepidoptera 13 38 15 Pyralidae 25 13 15 Ephydridae 6 38 12 Hebridae 19 13 12 Rare Tubificidae 29 75 38 52 Pezidae 100 71 44 42 Dytiscidae 14 13 75 27 Enchytraeidae 50 14 19 13 18 Hydrophilidae 50 13 38 18 Notonectidae 14 63 18 Arrenuridae 14 50 15 Unionicolidae 14 19 13 15 Veliidae 13 38 15 Hygrobatidae 50 12 Hydropsychidae 25 6 Hydryphantidae 25 6 Leptophlebiidae 25 6 Staphylinidae 13 6 Tipulidae 13 6 Aturidae 13 3 Corduliidae 13 3 Elmidae 6 3 Glossiphoniidae 13 3 Halacaridae 50 3 Hymenosomatidae 50 3 Mesoveliidae 6 3 Oxidae 13 3 Perthiidae 6 3 Pionidae 13 3 Spongillidae 6 3 233
5.16.4 Ecosystem Health
The Lower Murray Valley river ecosystem was in Poor Health (Lower and Middle Zones: Very Poor; Upper and Mt Lofty Zones: Poor). If the Mt Lofty Zone is excluded, the rating is Very Poor. Fish abundance was dominated by native species in all Zones, but biomass was dominated by alien species, and most expected species were absent. Most expected macroinvertebrate families were absent from the Murray and the Mt Lofty Zone, and many disturbance-sensitive families were absent. The regime had substantial long-term reductions in the magnitudes of mean and median annual flows and high -flows and there were substantial changes in variability and moderate changes in seasonality.
Summary Theme assessments are as follows (Table MVL.7): Hydrology Theme • Condition Index SR–HI = 50–60, indicating Poor Condition. • High-flow magnitudes reduced by 69–88%, 66% and 68–69% in the Upper, Middle and Lower Zones, respectively. • Little change in duration of periods of zero flows, but reductions in the magnitude of low flows by 45-58% in all three mainstem Zones. • All sites showed a 31–40% decline in variability (Moderate Difference from Reference Condition). • All sites showed a Moderate Difference from Reference Condition in seasonality. • Current mean annual volumes were reduced by 50% from Reference Condition values, and median annual volumes were reduced by 60–70%. All sites showed a Very Large Difference from Reference Condition. • No data were available for the streams of the Mt Lofty Zone. Fish Theme • Condition Index SR–FI = 53 (CL 49–58), indicating Poor Condition, but above the average (SR–FI = 37) for all Valleys. Condition was similar among Zones (Lower, Middle, Upper, Mt Lofty Zones: all Poor). • Twenty species caught, including six alien species. • Predicted native species reduced in the Lower (68%), Middle (62%) and Upper Zones (65%), and the Mt Lofty Zone (57%). • Mean abundance 219 fish per site, mainly native species (90%). • Biomass favoured alien species (61%). Macroinvertebrate Theme • Condition Index SR–MI = 48 (CL 47–56), indicating Poor Condition (Lower, Middle Zones: Very Poor; Upper and Mt Lofty Zones: Poor). • Low diversity and very to extremely low proportions of expected families across all three Zones in the Murray. • Moderate diversity in the Mt Lofty Zone and very low proportions of expected families across all three Murray Zones. • Reduced representation of expected disturbance-sensitive families, especially in the Mt Lofty Zone. 234
Table MVL.7: Lower Murray Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley. An ellipsis indicates no data (a Zone not identified for this Theme)
Zone
Valley Lower Middle Upper Mt Lofty
Hydrology Condition Poor Poor Poor Poor . . . Rating
Fish Index 53 (49–58) 50 (41–53) 58 (54–63) 55 (49–59) 42 (27–59) Rating Poor Poor Poor Poor Poor
Macroinvertebrate Index 48 (47–56) 31 (23–41) 39 (29–42) 56 (48–62) 55 (44–67) Rating Poor Very Poor Very Poor Poor Poor
Ecosystem Health Very Very Poor Poor Poor Rating Poor Poor
235
5.17 Murray Valley, Central
5.17.1 Hydrology
Figure MVC.1: Central Murray Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for the Central Murray mainstem were 64–77, indicating Moderate Condition throughout.
The Central Murray Valley extends from below Lake Hume to Lock 10, below the Murray-Darling junction at Wentworth. Major tributaries include the Murrumbidgee, Darling, Kiewa, Ovens, Goulburn, Campaspe and Loddon rivers. In addition to Lake Hume, there are lesser instream storages at Yarrawonga, Torrumbarry, Mildura and Wentworth weirs, used to provide hydraulic heads for diversions and to regulate flows to meet downstream demand. Tributary flows are highly modified before they reach the Murray. Limited channel capacity near Barmah (Barmah Choke: <9 GL/day) means that some irrigation releases are diverted via the Edward River. 236
Figure MVC.1 shows values of the Hydrology Index for five selected sites and Table MVC.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). All five sites in the Central Murray showed a Moderate Difference from Reference Condition (SR–HI = 64–77), although values of the index decline gradually along the Valley. The indicators show:
• High-Flow Events: Magnitudes reduced by 20–70% throughout. Moderate Difference from Reference Condition at Site 5; Very Large Difference at other selected sites, indicating major reductions in the magnitude of high-flow events. • Low- and Zero-Flow Events: A Moderate Difference from Reference Condition was apparent at Site 3, but other selected sites were Near Reference Condition. Zero flows are not likely to occur and there was no substantial change in the magnitude of low flows. • Variability: Near Reference Condition at all, except Sites 1 and 5, which showed a Moderate Difference from Reference Condition. Reductions of 5–25% in flow variability, with some exceptions. • Seasonality: A Very Large Difference from Reference Condition at Site 5, and a Large Difference at Site 3; otherwise a Moderate Difference, with shifts of 1–2 months, at most sites. • Gross Volume: Mean and median annual flow volumes in the Lower Zone were reduced by 40% and 55–60%, respectively, from Reference Condition, and by 10–40% and 20– 50%, respectively, for most Upper and Middle Zone sites. Site 5 was Near Reference Condition, and other sites indicated a Large Difference. Although values of the Hydrology Index varied only slightly at the selected sites (SR–HI = 64– 77), the indicators show that the nature of changes differed between sites. At Site 5, upstream from major diversions, the main change is in seasonality, as winter-spring runoff is captured in Lakes Dartmouth and Hume to provide irrigation in summer. Values of GV, HFE and LZFE are preserved, although possibly redistributed over in time. At Site 4, downstream of diversions at Yarrawonga and Torrumbarry, there is a marked reduction in GV and HFE, but some recovery in S as the un-seasonal peak of irrigation releases is removed. This effect is progressively amplified by further diversions downstream, and possibly by modified tributary inflows. In general, the flow regime of the Central Murray is modified by reductions in the magnitude of high-flow events and annual flow volumes, with significant shifts in seasonality.
237
Table MVC.1: Central Murray Valley: SR Hydrology Index and indicators. Sites are shown in Figure MVC.1. DS: downstream Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Murray DS Mildura Lower 64 29 97 78 62 45 2 Murray DS Euston Lower 67 30 92 81 65 48 3 Murray DS Wakool Junction Middle 67 36 78 90 58 59 4 Murray DS Torrumbarry Middle 71 36 89 88 60 58 5 Murray at Corowa Middle 77 77 100 73 29 81
238
5.17.2 Fish
100 Good 80 Moderate 60 63 54 51 54 Poor 40 Very Poor 20 Extremely Poor 0 Valley lower middle upper
Figure MVC.2: Central Murray Valley: fish sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 239
The Central Murray Valley fish community was in Poor Condition. The intrusion of alien species was moderate compared to some other Valleys, and native fish were relatively abundant, but only 40% of predicted native species were found. Substantial species richness had been lost.
Sampling of the Central Murray Valley was completed in January–March, 2005. Twenty one sites were sampled in three Zones, yielding 3,117 fish. Analyses indicated a Large (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 54 (CL 40–64). • Only 40% of predicted native fish species were recorded. • Nativeness showed a Moderate (±) Difference from Reference Condition. Figure MVC.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MVC.2 shows Index values, Indicators, Metrics and derived variables. There were 9-10 native species in each Zone, with 3-4 alien species. Only 39-45% of predicted native species were recorded among Zones. For the Valley in general, the diversity of native fish was much less than suggested by Reference Condition, with only 40% of predicted native species being recorded. The Central Murray Valley community showed a Large (+) Difference from Reference Condition (Lower Zone: Moderate (–) Difference, Middle Zone: Large (–) Difference, Upper Zone: Large (±) Difference). The Valley community compares well with other Valleys (only six Valleys had a higher score). Variations in the index and indicators were moderate, showing similar conditions in Zones. The ‘Lower’, ‘Middle’, and ‘Upper’ Zones of the Murray Valley ensured that sites were distributed appropriately. They do not represent strong altitudinal or biogeographic differences but are subject to management–related differences, with cold–water pollution and inverted seasonal flow patterns in the Middle Zone and a major irrigation diversion in the Middle Zone. Upper-Zone samples contained less than half the numbers of native fish found in the other Zones. The Middle Zone is downstream of Hume Dam and subject to depressed summer temperatures and a seasonal temperature lag (e.g. Walker 1992). Fish were abundant (average 148 per site). Across the Valley, 93% of individual fish were native, but the alien fish were larger (830 g cf. 56 g) and accounted for roughly half of the biomass. The numbers of native species in the three Zones were less than half those predicted under Reference Condition, with an overall 40% across the Valley. Native species richness is much reduced relative to Reference Condition. Carp dominated the alien species, although Goldfish and Eastern gambusia were common and occasional Redfin perch were caught. Table MVC.3 shows that species not caught in Zones where they were expected to be common under Reference Condition included Trout cod and Freshwater catfish. Other species not caught, but expected to be rare or moderately rare in one or more Zones under Reference Condition, included Macquarie perch, Freshwater catfish, River blackfish, Trout cod and Southern purple- spotted gudgeon. Across the Valley, less than 3% of fish showed Abnormalities in all except the Upper Zone (4.7%). One Intolerant species was recorded. Macro-carnivores were common in the Lower and Middle Zones but rare in the Upper Zone. Mega-carnivores were common in all Zones.
240
Table MVC.2: Central Murray Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lower Middle Upper
Fish Index 54 (40–64) 63 (56–74) 51 (37–59) 54 (31–71) Expectedness Indicator 42 (35–49) 46 (46–56) 44 (33–47) 40 (26–52) Nativeness Indicator 67 (43–83) 78 (64–91) 57 (40–74) 69 (38–96) Metrics Total species 14 12 14 13 Native (RC–F) species 10 9 10 9 Predicted RC–F species count 25 23 22 21 Alien species 4 3 4 4 Caught/Predicted native species (%) 40 39 45 43 Numbers of fish Mean fish per site all species 148 196 167 82 Native individuals (%) 93 94 92 94 Fish biomass Total biomass/site all species (g) 16,213 24,717 15,297 8,626 Mean biomass/fish (g) 109 126 92 105 Mean alien biomass/fish (g) 830 860 910 562 Mean native biomass/fish (g) 56 76 23 74 Biomass native (%) 48 57 23 66
241
Table MVC.3: Central Murray Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown as numbers; species not predicted shown as blanks
Native species Zone Total Lower Middle Upper
Australian smelt 541 673 218 1,432 Bony herring 405 11 16 432 Carp gudgeons 66 58 248 372 Congolli 0 0 0 Dwarf flat-headed gudgeon 0 0 0 0 Flat-headed gudgeon 3 48 1 52 Freshwater catfish 0 0 0 0 Golden perch 14 6 11 31 Macquarie perch 0 0 0 0 Mountain galaxias 0 0 Murray cod 18 17 23 58 Murray hardyhead 0 0 0 0 Flat-headed galaxias 0 0 0 0 Murray–Darling rainbowfish 27 90 5 122 Obscure galaxias 0 0 Olive perchlet 0 0 0 0 River blackfish 0 0 Short–finned eel 0 0 Short-headed lamprey 0 0 0 0 Silver perch 5 7 4 16 Southern purple-spotted gudgeon 0 0 0 0 Southern pygmy perch 0 0 0 0 Spangled perch 0 0 0 Trout cod 0 12 0 12 Un-specked hardyhead 209 154 12 375 Alien species
Carp 72 67 23 162 Eastern gambusia 10 4 7 21 Goldfish 5 15 3 23 Redfin perch 5 4 9 242
5.17.3 Macroinvertebrates
100 Good 80 Moderate 60 46 49 Poor 40 43 Very Poor 26 20 Extremely Poor 0 Valley lower middle upper
Figure MVC.3: Central Murray Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median
243
The Central Murray Valley macroinvertebrate community was in Poor Condition, with two Zones in Poor Condition and the Middle Zone in Very Poor Condition. Most sites had impoverished faunas, lacking some disturbance-sensitive families.
Thirty five sites were surveyed across three Zones of the Central Murray Valley in October 2005, yielding 6,667 macroinvertebrates and 57 families (40% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 46 (CL 41–50). • Low proportion of expected families (Filters OE = 25). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 92). SR–MI for the Central Murray Valley is the fifth lowest score of all Valleys (cf. Murrumbidgee, Lower Murray). The Lower and Upper Zone communities each showed a Large Difference from Reference Condition (SR–MI = 43, 49 respectively), and the Middle Zone community showed a Very Large Difference (SR–MI = 26). Figure MVC.3 shows sampling sites, Zones and SR–MI values, and Table MVC.4 shows metrics and derived variables. Only 59% of the expected families were recorded in the Valley, and family richness was less than Reference Condition at all sites. Diversity was moderate to low (average 17 families per site), with substantial variation among sites. Most (89%) of the Valley fauna was in the Upper Zone (cf. 51 and 67% for the Lower and Middle Zones). Table MVC.5 shows that Expected (Filters OE) scores indicated substantial to severe loss of expected families. No sites had a high Filters OE score, and eight (19% of stream length) had a low score. Filters SIGNAL OE scores were reduced for all Zones, with 20% of sites (and stream length) with a high score and 80% with a reduced score. Most communities were impoverished and had lost disturbance-sensitive families. Table MVC.6 shows ‘common’ and ‘rare’ families. The five common families, all of which favour still or slow–flowing habitats, were water bugs (Corixidae, Naucoridae), shrimps (Atyidae), semi-aquatic beetles (Staphylinidae) and an aquatic millipede (Siphonotidae). The 17 rare families included diving beetles (Dytiscidae) and midges (Chironomidae), and others associated with fast–flowing habitats. 244
Table MVC.4: Central Murray Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lower Middle Upper
Index 46 43 26 49 SR–MI (41–50) (39–55) (22–35) (44–54) Metrics 25 23 17 27 Filters OE (23–27) (22–29) (16–20) (25–29) Filters SIGNAL OE 92 95 89 92 (87–97) (89–119) (79–97) (87–97) Families Families per site 17 16 14 19 minimum – maximum 10–29 14–18 10–25 10–29 Total families 57 30 37 51
Table MVC.5: Central Murray Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lower Middle Upper
n sites 35 4 8 23
Filters OE High Medium 27 4 2 21 Low 8 6 2 Filters SIGNAL OE High 7 1 1 5 Medium 24 3 5 16 Low 4 2 2 245
Table MVC.6: Central Murray Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 4 8 23 35 Number of families sampled 31 41 54 61 Percent of families in Basin 27.0 35.7 47.0 40.1 Percent of families in Valley 51 67 89 100
Percent of sites by Zone Lower Middle Upper VALLEY
Common Corixidae 100 100 100 100 Atyidae 100 100 96 97 Naucoridae 25 50 26 31 Staphylinidae 50 30 31 Siphonotidae 25 6 Rare Chironominae 100 38 83 74 Tanypodinae 100 25 74 66 Dytiscidae 25 38 74 60 Oligochaeta 13 48 34 Corduliidae 13 26 20 Ecnomidae 13 9 Gripopterygidae 13 4 6 Corallanidae 25 3 Haliplidae 25 3 Hebridae 4 3 Hydrobiosidae 13 3 Hydropsychidae 13 3 Megapodagrionidae 4 3 Pleidae 25 3 Psychodidae 4 3 Sphaeriidae 4 3 Tabanidae 4 3
246
5.17.4 Ecosystem Health
The Central Murray Valley river ecosystem was in Poor Health (Lower Zone: Moderate; Middle Zone: Very Poor; Upper Zone: Poor). Fish abundance was dominated by native species, but biomass half alien species, and most expected fish species were absent. Most expected and many disturbance-sensitive macroinvertebrate families were absent. High flows and annual flow volumes were reduced, and there were significant shifts in flow seasonality.
Summary Theme assessments are as follows (Table MVC.7): Hydrology Theme • Condition Index SR–HI = 64–77 for five mainstem locations, indicating Moderate Condition. • High flows reduced by 20–70%. • No substantial changes in duration of zero flows or magnitudes of low flows. • Flow variability showed a Moderate Difference from Reference Condition, reduced by 5– 25% at most sites. • Seasonality exhibited a Very Large to Moderate Difference from Reference Condition throughout, with shifts of several months. • Mean and median annual flow volumes were reduced relative to Reference Condition by about 40% and 55–60%, respectively, in the Lower Zone, and 10–40% and 20–50%, respectively, at most Upper and Middle Zone sites. Fish Theme • Condition Index SR–FI = 54 (CL 40–64), indicating Poor Condition, above the average (SR–FI = 37) for all Valleys. Condition varied among Zones (Lower Zone: Moderate; Middle Zone: Very Poor; Upper Zone: Poor). • Fourteen species caught, including four alien species. • Predicted native species reduced in the Lower (61%), Middle (55%) and Upper Zones (57%). • Mean abundance 148 fish per site, overwhelmingly native species (93%). • Biomass slightly favoured alien species (52%). Macroinvertebrate Theme • Condition Index SR–MI = 46 (CL 41–50), indicating Poor Condition (Lower, Upper Zones: Poor; Middle Zone: Very Poor). • Low to moderate diversity and low to very low proportions of expected families in all Zones. • Reductions of expected disturbance-sensitive families in all Zones.
247
Table MVC.7: Central Murray Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lower Middle Upper
Hydrology Condition Moderate Moderate Moderate Moderate Rating Fish Index 54 (40–64) 63 (56–74) 51 (37–59) 54 (31–71) Rating Poor Moderate Poor Poor
Macroinvertebrate Index 46 (41–50) 44 (39–55) 26 (22–35) 49 (44–54) Rating Poor Poor Very Poor Poor
Ecosystem Health Very Poor Moderate Poor Rating Poor
248
5.18 Murray Valley, Upper
5.18.1 Hydrology
Figure MVU.1: Upper Murray Valley Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Condition of the Upper Murray Valley was Moderate to Good (Slopes Zone: Moderate to Good; other Zones: Good). Hydrology Index scores were 47–100 for selected sites. The Slopes Zone downstream of Khancoban Pondage was Poor to Good. Other sites were rated Good, with little or no change compared to Reference Condition.
The Murray rises on the western slopes of the Great Dividing Range west of Albury-Wodonga. The headwater tributaries, in descending order of mean annual discharge, are the Swampy Plain River, Corryong, Cudgewa, Limestone, Burrowye, Koetong (which now discharges into Lake Hume), Walwa and Johnston Creeks. From the Junction of Cudgewa Creek, the Murray continues westward to enter the ‘Murray Arm’ of Lake Hume. Much of the catchment is forested, but there is some irrigated agriculture, particularly near Corryong. The main hydrological change is the 249 inter-valley transfer of water via the Snowy Mountains Scheme, which discharges into the Upper Murray near Khancoban, more than doubling the mean annual flow at that point. The lower reaches are impounded as part of Lake Hume. Figure MVU.1 shows values of the Hydrology Index for five selected sites and Table MVU.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at all sites in tributaries was Near Reference (SR–HI = 100), exept for the Swampy Plain River, immediately downstream of the inter-valley transfer near Khancoban, where Condition declined to a Large Difference from Reference (SR–HI = 47), changing to Near Reference Condition further downstream in the Murray (SR–HI = 83). The indicators show:
• High-Flow Events: Magnitude of high flows was more than doubled immediately downstream of Khancoban on the Swampy Plain River (Site 2, Very Large Difference from Reference), but recovered further downstream. Other sites were Near Reference Condition. • Low- and Zero-Flow Events: Sites 1 and 2, showed a Moderate Difference from Reference Condition, characterised by major increases in low flows but no change in zero-flow durations (the river is naturally perennial). Other sites were Near Reference Condition. • Variability: Site 2 showed a Large Difference from Reference Condition, due to sustained large releases from Khancoban Pondage, declining downstream (e.g. Site 1: Moderate Difference from Reference Condition). Other sites were Near Reference Condition. • Seasonality: All sites were Near Reference Condition. • Gross Volume: Site 2 showed a Very Large Difference from Reference Condition, due to increases in median and mean annual volumes in the tributary Swampy Plain River. Other tributary sites were Near Reference Condition, damping the effect of inter-valley transfers from the Snowy Mountains Scheme. Site 2, on the Swampy Plain River downstream from an inter-valley transfer, showed a typical response to augmented flow (modelled current annual flow is 213% of modelled natural annual flow). Gross Volume (GV), Variation (V), and High-Flow Events (HFE) and to a lesser extent Low- and Zero-Flow Events (LZFE) were changed, but Seasonality (S) was little affected. Inflows to the Murray downstream from Corryong and Cudgewa Creeks (Sites 3–4) countered the effects apparent at Site 1. In general, the flow regime of the Upper Murray Valley is characterised by substantial changes in volumes, variability and the magnitudes of high- and low-flows in the Swampy Plain River below Khancoban Pondage, but elsewhere there is little difference from Reference Condition.
250
Table MVU .1: Upper Murray Valley: SR Hydrology Index and indicators. Sites are shown in Figure MVU .1
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Murray at Jingellic Slopes 83 94 60 70 89 86 Swampy Plain River at 2 Khancoban Slopes 47 27 60 44 80 38 3 Cudgewa Creek Outlet Slopes 100 100 100 100 100 100 4 Corryong Creek Outlet Slopes 100 100 100 99 97 100 5 Limestone Creek Montane 100 100 100 100 100 95
251
5.18.2 Fish
100 Good 80 Moderate 60 Poor 40 38 Very Poor 20 14 9 8 Extremely Poor 0 Valley slopes upland montane
Figure MVU.2: Murray Valley, Upper showing sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 252
The Upper Murray Valley fish community was in Extremely Poor Condition. Less than half the predicted native species were caught, and alien species, mainly trout, were 96% of total biomass and 74% of total abundance.
Twenty one sites across three Zones in the Upper Murray Valley were surveyed in March 2005, yielding 881 fish. Analyses showed an Extreme (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 14 (CL 14–26). • Expectedness showed a Very Large Difference from Reference Condition. • Nativeness showed an Extreme (+) Difference from Reference Condition. • The percentage of total biomass that was native (4%) was extremely low. Figure MVU.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MVU.2 shows Index values, Indicators, Metrics and derived variables. Three of the four RC–F species were recorded from Montane Zone sites, producing a higher proportion of caught to predicted species (75%) than other Zones. Seven alien species were found in the Slopes Zone, and three in each of the others. The Upper Murray Valley showed an Extreme (+) Difference from Reference Condition (Slopes Zone: Extreme (+) Difference, Upland Zone: Extreme (+) Difference, Montane Zone: Very Large (+) Difference). Only four Valleys had lower Fish Index scores than the Upper Murray Valley. Fewer than half (47%) of the Valley’s predicted (RC–F) native species were caught. Variation was low in the overall Index and in Nativeness and Expectedness, indicating relatively homogeneous conditions for native fish across the Valley and Zones. Nativeness was low, however, and varied substant- ially in all Zones. Few fish were collected compared to other Valleys (average 42 fish per site), and the proportion of total biomass contributed by native species (4%) was extremely low. The RC–F species, mostly small fish, were outweighed (average mass 9 g v. 134 g) and outnumbered (36% to 64%) by alien species, mainly trout. Native fish diversity was very low throughout the Valley, but occasional sites had numerous Mountain galaxias, River blackfish or Two–spined blackfish. Table MVU.3 shows a summary of native species abundances. Riffle galaxias and Macquarie perch were not caught in the Zones where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Golden perch, Murray cod, Trout cod, Silver perch and smaller, less well-known species. Alien species, other than trout, included numerous Redfin perch and Carp, plus occasional Eastern gambusia and Goldfish. Very few fish in the catches showed Abnormalities. No Mega-carnivores were caught. Several Intolerant species were recorded. 253
Table MVU.2: Upper Murray Valley: Index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Slopes Upland Montane
Fish Index 14 (14–26) 9 (5–28) 8 (8–32)38 (38–55) Expectedness Indicator 31 (31–40) 22 (21–32) 25 (25–46)53 (53–60) Nativeness Indicator 0 (0–23) 17 (0–29) 0 (0–29) 0 (0–43) Metrics Total species 14 13 7 6 Native species 7 6 4 3 Predicted RC–F species count 15 15 9 4 Alien species 7 7 3 3 Caught/Predicted native species (%) 47 40 44 75 Numbers of fish Mean fish per site 42 26 62 37 Native individuals (%) 36 36 37 35 Fish biomass Biomass/site all species (g) 3,723 8,247 1,855 1,066 Mean native biomass/fish (g) 9 14 10 3 Mean alien biomass/fish (g) 134 477 42 42 Biomass native (%) 4 2 12 3
254
Table MVU.3: Upper Murray Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Slopes Upland Montane
Australian smelt 6 0 6 Carp gudgeons 1 1 Climbing galaxias 4 6 10 Flat-headed gudgeon 0 0 0 Riffle galaxias 0 8 3 11 Golden perch 0 0 Macquarie perch 0 0 0 0 Mountain galaxias 16 92 84 192 Murray cod 0 0 0 Flat-headed galaxias 0 0 Obscure galaxias 9 9 River blackfish 33 22 55 Silver perch 0 0 Southern pygmy perch 0 0 Trout cod 0 0 0 Two–spined blackfish 1 40 5 46
Alien species
Brown trout 20 173 98 Carp 32 Eastern gambusia 9 Goldfish 1 Rainbow trout 1 113 66 Redfin perch 52 1 255
5.18.3 Macroinvertebrates
100 Good 80 77 65 69 Moderate 60 56 Poor 40 Very Poor 20 Extremely Poor 0 Valley slopes upland montane
Figure MVU.3: Upper Murray Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 256
The Upper Murray Valley macroinvertebrate community was in Moderate Condition, with its three Zones in Poor to Moderate Condition. Communities at most sites were impoverished and lacked disturbance-sensitive families.
Thirty four sites were surveyed across three Zones of the Upper Murray Valley in November 2005, yielding 14,034 macroinvertebrates in 86 families (60% of Basin families). Analyses showed a Moderate Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 65 (CL 59–69). • Moderate proportion of expected families (Filters OE = 31). • SIGNAL OE score near Reference Condition (Filters SIGNAL OE = 107). SR–MI for the Upper Murray Valley was the second highest score of all Valleys, marginally below that for the Border Rivers and slightly above that for the Paroo. The Slopes Zone community showed a Large Difference from Reference Condition (SR–MI = 56), and the Upland and Montane Zone communities showed Moderate and Moderate (+) Differences (SR–MI = 69, 77 respectively). Figure MVU.3 shows sampling sites, Zones and SR–MI values, and Table MVU.4 shows metrics and derived variables. Eighty three percent of expected families were recorded in the Valley, and family richness was less than Reference Condition at all sites except one. Diversity was moderate to high (average 32 families per site). Most (91%) of the Valley fauna was in the Upland Zone (cf. 71 and 76% for the Slopes and Montane Zones). Table MVU.5 shows that Expected (Filters OE) scores indicated moderate to substantial loss of expected families. No sites had a high Filters OE score. Filters SIGNAL OE scores were high for all Zones, and a high proportion of sites (71% of stream length) had a high score. Communities at most sites have low diversity, but still retain most disturbance-sensitive families. Table MVU.6 shows ‘common’ and ‘rare’ families. The 33 common families were dominated by 28 aquatic insect families that favour fast–flowing, cool habitats. In contrast, the 19 rare families included many associated with slow–flowing or still waters. 257
Table MVU.4: Upper Murray Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Slopes Upland Montane
Index SR–MI 65 56 69 77 (59–69) (48–62) (56–71) (65–81) Metrics Filters OE 31 28 32 35 (29–32) (24–30) (30–33) (30–37) Filters SIGNAL OE 107 102 109 115 (101–111) (96–108) (95–114) (106–118) Families Families per site 32 30 33 33 minimum – maximum 16–40 16–39 24–40 28–37 Total families 86 66 79 60
Table MVU.5: Upper Murray Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Slopes Upland Montane
Number of sites 34 14 12 8
Filters OE High Medium 33 13 12 8 Low 1 1 Filters SIGNAL OE High 24 8 8 8 Medium 10 6 4 Low 258
Table MVU.6: Upper Murray Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 14 12 8 34 Number of families sampled 65 78 61 86 Percent of families in Basin 53.3 69.6 61.6 60.1 Percent of families in Valley 76 91 71 100
Percent of sites by Zone Slopes Upland Montane VALLEY
Common Leptoceridae 100 100 100 100 Leptophlebiidae 93 100 100 97 Orthocladiinae 100 100 88 97 Baetidae 100 92 88 94 Elmidae 93 92 100 94 Gripopterygidae 100 83 100 94 Hydrobiosidae 86 92 100 91 Simuliidae 86 92 88 88 Tipulidae 86 83 100 88 Hydropsychidae 71 92 100 85 Oligochaeta 93 83 75 85 Conoesucidae 79 67 100 79 Aeshnidae 50 58 100 65 Scirtidae 43 50 88 56 Glossosomatidae 50 42 63 50 Oniscigastridae 64 42 25 47 Gomphidae 64 42 13 44 Austroperlidae 14 50 63 38 Corydalidae 7 42 88 38 Helicopsychidae 21 33 63 35 Philopotamidae 14 25 88 35 Athericidae 21 33 50 32 Synlestidae 36 17 38 29 Eusiridae 25 63 24 Sphaeriidae 7 25 38 21 Atriplectididae 7 17 25 15 Limnephilidae 14 17 13 15 Megapodagrionidae 7 25 12 Odontoceridae 17 13 9 Ameletopsidae 17 6 Gelastocoridae 7 8 6 Gordiidae 8 13 6 Isopoda 25 6 Rare Corixidae 93 67 13 65 Notonectidae 57 42 38 Parastacidae 7 8 6 Tasimiidae 7 8 6 Antipodoeciidae 8 3 Aphroteniinae 8 3 Culicidae 8 3 Hydrobiidae 13 3 Lepidoptera 7 3 259
Libellulidae 7 3 Mesoveliidae 8 3 Naucoridae 7 3 Neoniphargidae 13 3 Nepidae 7 3 Nevrothidae 8 3 Osmylidae 8 3 Paramelitidae 13 3 Podonominae 13 3 Psychodidae 8 3
260
5.18.4 Ecosystem Health
The Upper Murray Valley river ecosystem was in Very Poor Health (Slopes and Upland Zones: Very Poor; Montane Zone: Poor). Fish abundance and biomass were dominated by alien species and several expected species were absent. Many expected macroinvertebrate families were absent, but few disturbance-sensitive families were absent. The flow regime showed substantial changes in volumes, variability and the magnitudes of high and low flows in the Swampy Plain River and the Murray downstream of Khancoban Pondage, but elsewhere little difference from Reference Condition.
Summary Theme assessments are as follows (Table MVU.7): Hydrology Theme • Hydrological Index scores were 47–100, indicating Moderate to Good Condition. • Magnitude of high flows more than doubled downstream of Khancoban on the Swampy Plain River, the major inflow to the Murray, but recovered downstream. Other sites were Near Reference Condition. • Low and zero flows showed Moderate Difference from Reference Condition downstream of Khancoban, characterised by large increases in the magnitude of low flows but no change in zero-flow durations (the river was naturally perennial). Other sites were Near Reference Condition. • Large Difference from Reference Condition in variability due to large and relatively constant releases from Khancoban Pondage, declining downstream. Other sites were Near Reference Condition. • GV showed Very Large Difference from Reference Condition downstream of Khancoban, due to increases in median and mean annual volumes in the Swampy Plain River. Other tributary sites were Near Reference Condition, countering the effect inter-valley transfers from the Snowy Scheme on the Murray mainstem downstream. • All sites were Near Reference Condition in seasonality. Fish Theme • Condition Index SR–FI = 14 (CL 14–26), indicating Extremely Poor Condition, in the lower range for all Valleys. Condition varied among Zones (Slopes, Upland Zones: Extremely Poor; Montane Zone: Very Poor). • Fourteen species were caught, including seven alien species. • Predicted native species reduced in the Slopes (60%), Upland (56%) and Montane Zones (25%). • Mean abundance 42 fish per site, mainly alien species (64%). • Biomass overwhelmingly alien species (96%). Macroinvertebrate Theme • Condition Index SR–MI = 65 (CL 59–69), indicating Moderate Condition (Slopes Zone: Poor; Upland, Montane Zones: Moderate). • Moderate to high diversity but low proportions of expected families in all Zones. • Retention of most disturbance-sensitive families in all Zones. 261
Table MVU.7. Upper Murray Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley
Zone
Valley Slopes Upland Montane
Hydrology Condition Moderate Moderate Good Good Rating to Good to Good
14 (14–26) 9 (5–28) 8 (8–32) 38 (38–55) Fish Index Extremely Extremely Extremely Very Rating Poor Poor Poor Poor
Macroinvertebrate Index 65 (59–69) 56 (48–62) 69 (56–71) 77 (65–81) Rating Moderate Poor Moderate Moderate
Ecosystem Health Very Very Very Poor Rating Poor Poor Poor
262
5.19 Murrumbidgee Valley
5.19.1 Hydrology
Figure MUR.1: Murrumbidgee Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Murrumbidgee Valley were 38–95, indicating Poor to Moderate Condition (Lowland Zone: Poor to Moderate; Slopes Zone: Poor to Good). Condition at sites between the major storages and the outflow to the Murray was Poor to Moderate.
The Murrumbidgee Valley in southern New South Wales covers about 88,000 km2, or about 7.5% of the Basin area. There is one major tributary, the Tumut River, in the south-west, lesser streams including the Queanbeyan, Yass and Cotter rivers in the upper reaches and Tarcutta and Mirrool Creeks downstream of the Tumut junction. At this point the river enters a broad floodplain and flows westward. In big floods, water from the Lachlan River can enter the lower Murrumbidgee via the Great Cumbung Swamp. 263
The Murrumbidgee is intensively regulated and supports major irrigation areas, with perennial horticulture in the mid-reaches and rice and other annual crops to the west. Major dams are Burrinjuck on the Murrumbidgee (1,025 GL) and Blowering on the Tumut (1,631 GL). Four smaller dams (Googong, Corin, Bendoura, Cotter) supply Canberra and the Australian Capital Territory, and there is another on the upper Tumut River. Inter-valley transfers occur as part of the Snowy Mountains Scheme. Diversions to Blowering Dam cause flows in the Tumut to be about double the modelled natural annual flows. Water is transferred from the Murrumbidgee via Yanco Creek to Billabong Creek and the Murray via the Edward River. Figure MUR.1 shows the value of the Hydrology Index, SR–HI, for five selected sites and Table MUR.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at the four sites on the Murrumbidgee ranged from Near Reference (SR–HI = 95) upstream of Burrinjuck Dam (but below other storages) to a Moderate to Large Difference from Reference Condition downstream (SR–HI = 57–74). The Tumut River, influenced by Blowering Dam, showed a Very Large Difference (SR–HI = 38). The indicators show:
• High-Flow Events: These were reduced by 25–63% relative to Reference Condition. The Tumut River showed 62–82% increases in HFE relative to Reference Condition. Site 5 showed an Extreme Difference from Reference Condition; Sites 3–4 showed a Moderate Difference and Sites 1–2 showed a Large Difference. • Low- and Zero-Flow Events: Both the Murrumbidgee and Tumut rivers showed substantial changes in the duration and magnitude of low flows, but no change in the duration of zero flows (both are perennial rivers). The Murrumbidgee had more frequent low flows than under Reference Condition, particularly in winter-spring. These events were less common in the Tumut, due to inter-valley transfers. Sites 3 and 5 showed a Moderate Difference from Reference Condition, perhaps reflecting flows from inter-valley transfers. Sites 1, 2 and 4 were Near Reference Condition. • Variability: Variability in the Murrumbidgee downstream of Gundagai was reduced by 26–74% relative to Reference Condition, and in the Tumut River by 23–51%. At Site 1, a Large Difference from Reference Condition was recorded, reflecting substantial upstream diversions. Sites 3 and 5 showed a Moderate Difference from Reference Condition; Sites 2 and 4 were Near Reference Condition. • Seasonality: The Tumut (Site 5) showed an Extreme Difference from Reference Condition (the lowest score of all 469 sites examined in the Basin). The Tumut hydrograph has changed from a winter-spring flow peak (October) to a poorly-defined bimodal pattern with maxima in March and October. The Murrumbidgee upstream of Burrinjuck (Site 4) was Near Reference Condition, but the remaining Murrumbidgee sites showed Moderate to Large Differences from Reference Condition. The seasonal pattern of high flows was similar to natural conditions, but the peak median monthly flows shifted slightly towards late spring, and the lowest median monthly flows moved to May-June. • Gross Volume: Mean annual volume was reduced by 11–52% relative to Reference Condition in the Murrumbidgee, with the greatest reduction downstream of Balranald Weir (Site 1). GV was approximately doubled in the Tumut River. There were also substantial reductions by up to 52% in median annual flows in the Murrumbidgee (Site 1) and increases of about 70% in the Tumut River. There was a Very Large Difference from 264
Reference Condition at Sites 1 and 5; Sites 3–4 were Near Reference Condition and Site 2 showed a Large Difference. • All tributaries in the Slopes Zone, and in the Lowland Zone (except the distributary Yanco Creek), were Near Reference Condition. Data for Site 4 indicate that, while there was some change in HFE, storages and diversions of water near Canberra have small effects on flows in the Murrumbidgee. Inter-valley transfer into the Tumut doubles GV in that system (S is depressed because most of the additional flow occurs during the irrigation season). GV is depressed also in the lower Murrumbidgee, but this is in response to diversions. At Site 1, GV now is less than half, on average, what it would have been naturally (this includes 880 GL diverted to the Tumut). In general, the flow regimes of the Murrumbidgee and Tumut Rivers are affected by major changes in the magnitude of annual volumes and high flows, and in Seasonality, but with little or no change elsewhere. Despite the doubling of flows in the Tumut, the volumes of water in the lower reaches of the Murrumbidgee are halved compared to natural conditions.
Table MUR.1: Murrumbidgee Valley: SR Hydrology Index and indicators. Sites are shown in Figure MUR.1. US: upstream; DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
Murrumbidgee 1 DS Balranald Weir Lowland 57 37 83 55 56 25 Murrumbidgee 2 at Darlington Point Lowland 74 47 100 83 66 56 Murrumbidgee 3 at Wagga Wagga Lowland 62 73 60 68 48 80 Murrumbidgee 4 US Burrinjuck Dam Slopes 95 73 99 91 91 92 5 Tumut at Odeys Bridge Slopes 38 18 72 67 10 33
265
5.19.2 Fish
100 Good 80 Moderate 60 Poor 40 42 41 Very Poor 20 14 Extremely Poor 0 00 Valley lowland slopes upland montane
Figure MUR.2: Murrumbidgee Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 266
The Murrumbidgee Valley fish community was in Extremely Poor Condition. The community had lost most of its native species richness and was dominated by alien fish, which were more than 87% of total biomass and 71% of total abundance. The Slopes and Upland Zone communities were in especially poor condition.
Twenty eight sites across four Zones in the Murrumbidgee Valley were surveyed in January and February 2007, producing 1,536 fish. Analyses indicated an Extreme (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 14 (CL 5–21). • Expectedness showed a Very Large (–) Difference from Reference Condition. • Nativeness showed a Very Large (–) Difference from Reference Condition. • The Slopes and Uplands Zones returned Fish Index scores of zero, indicating Extreme Differences from Reference Condition. • Native fish in the Slopes and Uplands Zones were in extremely low numbers compared to alien fish, averaging 17% and 6% per site, respectively. Figure MUR.2 shows sampling sites, Zones and corresponding SR–FI values, and Table MUR.2 shows Index values, Indicators, Metrics and derived variables. Only 40%, 28% and 17% of predicted (RC–F) native fish were recorded from the Lowland, Slopes and Upland Zones, respectively, and these Zones had four, six and seven alien species, respectively. Three of five RC–F species and five alien species were recorded in the Montane Zone. The Murrumbidgee Valley community showed an Extreme (+) Difference from Reference Condition (Lowland Zone: Large (–) Difference, Slopes and Upland Zones: Extreme Difference, Montane Zone: Large (–) Difference). Only four Valleys had lower Fish Index values than the Murrumbidgee Valley. Communities in the Slopes and Upland Zones were in particularly poor condition, with few predicted native species, high proportions of alien fish and very low proportions of native biomass. Narrow confidence intervals showed that Condition varied little among sites. Moderate numbers of fish were from Zones other than the Lowland Zone, where catches averaged only 19 fish per site. Proportions of native fish varied from 69% in the Lowland Zone to 6% in the Upland Zone. Across the Valley, native fish averaged 29% of all catches. Eastern gambusia, Rainbow trout, Redfin perch and Carp dominated the alien species. Smaller numbers of Goldfish, Oriental weatherloach and Brown trout also were present. Larger alien species, especially Rainbow trout, Carp and Redfin perch, dominated the biomass. The native fish all were small–bodied species, except for small numbers of Murray cod, River blackfish and Two–spined blackfish. There was an extremely low percentage of native biomass in the Slopes and Upland Zones, and an average of only 13% across the Valley. Table MUR.3 shows a summary of native species abundances. Freshwater catfish, Silver perch and Macquarie perch were not caught at any sites, but were expected to be common under Reference Condition. Other species not caught, but predicted to be rare or moderately rare in one or more Zones under Reference Condition, included Silver perch, Golden perch, Macquarie perch, Olive perchlet, River blackfish, Southern purple-spotted gudgeon, Trout cod, Two–spined blackfish and Freshwater catfish. 267
Few fish in the Upland and Slopes Zones showed Abnormalities (1% and 2.3% of catches, respectively), but there were more in the Lowland (12.3%) and Montane Zones (7.8%). Mega- carnivores such as Golden perch and Murray cod were not caught in the Slopes, Upland and Montane Zones. No Intolerant species were caught in the Lowland Zone, but 2-4 were found in other Zones.
Table MUR.2: Murrumbidgee Valley: Index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes Upland Montane
Fish Index 14 (5–21) 42 (23–50) 0 (0–7) 0 (0–3) 41 (31–49) Expectedness Indicator 22 (19–27) 33 (24–40) 10 (10–21) 2 (2–5) 46 (46–46) Nativeness Indicator 22 (10–30) 57 (29–65) 4 (0–19) 0 (0–22) 31 (13–47) Metrics Total species 20 12 11 9 8 Native species 13 8 5 2 3 Predicted RC–F species count 22 20 18 12 5 Alien species 7 4 6 7 5 Caught/Predicted native species (%) 59 40 28 17 60 Numbers of fish Mean fish per site 55 19 79 69 53 Native individuals (%) 29 69 17 6 63 Fish biomass Biomass/site all species (g) 4,494 7,469 3,045 5,820 1,642 Mean native biomass/fish (g) 38 169 3 1 5 Mean alien biomass/fish (g) 100 926 45 90 76 Biomass native (%) 13 29 1 0 10
268
Table MUR.3: Murrumbidgee Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes Upland Montane
Australian smelt 54 7 0 61 Bony herring 1 0 1 Carp gudgeons 8 73 2 83 Dwarf flat-headed gudgeon 0 1 1 Flat-headed gudgeon 1 0 1 Freshwater catfish 0 0 0 Golden perch 3 0 0 3 Macquarie perch 0 0 0 3 3 Mountain galaxias 1 26 184 211 Murray cod 14 0 0 14 Murray hardyhead 0 0 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 8 0 8 Olive perchlet 0 0 River blackfish 0 11 0 0 11 Short-headed lamprey 0 0 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 Southern pygmy perch 0 0 0 0 Trout cod 0 0 0 0 0 Two–spined blackfish 0 46 46 Un-specked hardyhead 1 0 1
Alien species
Brown trout 3 1 10 14 Carp 33 68 77 10 188 Eastern gambusia 1 225 79 11 316 Goldfish 5 21 5 27 58 Rainbow trout 8 210 77 295 Redfin perch 1 138 61 200 Oriental weatherloach 21 21
269
5.19.3 Macroinvertebrates
100 Good 80 Moderate 60 62 48 46 Poor 40 40 38 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure MUR.3: Murrumbidgee Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 270
The Murrumbidgee Valley macroinvertebrate community was in Poor Condition, with Upland and Montane Zone communities in poorer condition than those in the Lowland and Slopes Zones. Upland and Montane Zone communities had low diversity and had lost many disturbance- sensitive families.
Thirty five sites were surveyed across four Zones of the Murrumbidgee Valley in November 2004, yielding 8,710 macroinvertebrates in 76 families (53% of Basin families). Analyses showed a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 48 (CL 43–52). • Moderate to low proportion of expected families (Filters OE = 26). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 93). SR–MI for the Murrumbidgee Valley was the equal sixth lowest score of all Valleys (cf. Lower Murray, Central Murray). The Lowland Zone communities showed a Moderate (–) Difference from Reference Condition (SR–MI = 62), the Slopes and Upland Zones a Large (–) Difference (SR–MI = 40, 46 respectively) and the Montane Zone a Very Large (+) Difference (SR–MI = 38). Wide confidence intervals for SR–MI in all Zones (13-20 points) indicate variation in condition among sites. Figure MUR.3 shows sampling sites, Zones and SR–MI values, and Table MUR.4 shows metrics and derived variables. Seventy two percent of expected families were recorded in the Valley. Family richness was less than Reference Condition at over 40% of sites. Diversity was moderate (average 22 families per site), although Upland Zone sites were highly variable. Most (80-83%) of the Valley fauna was in the Upland and Montane Zones, compared with 59-68% for the Lowland and Slopes Zones. Table MUR.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Only one site in the Valley had a high Filters OE score, and four (16%) of sites in the Slopes to Montane Zones had low scores. Filters SIGNAL OE scores were near Reference Condition for the Lowland and Montane Zones, but less in the Upland Zone. Most communities above the Lowland Zone were impoverished and had lost disturbance-sensitive families. Table MUR.6 shows ‘common’ and ‘rare’ families. Four common families included damselflies (Corduliidae), pond snails (Lymnaeidae), ‘pill’ clams (Sphaeriidae) and isopods (Phreatoicidae). These are all families of still and slow-flowing aquatic habitats. The 15 rare families included many—bugs (Corixidae), beetles (Hydraenidae), molluscs (Ancylidae, Hydrobiidae)—that are associated with similar habitats, but are uncommon in the Murrumbidgee Valley. 271
Table MUR.4: Murrumbidgee Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 48 62 46 40 38 (43–52) (51–71) (36–49) (31–52) (29–47) Metrics Filters OE 26 34 26 26 21 (24–28) (27–37) (23–27) (20–29) (20–25) Filters SIGNAL OE 93 97 88 78 94 (85–97) (94–105) (76–93) (78–102) (75–105) Families Families per site 22 21 24 24 22 minimum – maximum 8–33 16–26 15–27 8–33 15–33 Total families 76 45 52 62 62
Table MUR.5: Murrumbidgee Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 35 10 7 7 11
Filters OE High 1 1 Medium 30 9 6 6 9 Low 4 1 1 2 Filters SIGNAL OE High 9 3 1 2 3 Medium 17 7 4 1 5 Low 9 2 4 3
272
Table MUR.6: Murrumbidgee Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 10 7 7 11 35 Number of families sampled 48 55 65 67 81 Percent of families in Basin 41.7 42.0 55.6 63.8 53.3 Percent of families in Valley 59 68 80 83 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY
Common Corduliidae 80 14 43 55 51 Lymnaeidae 14 43 45 26 Phreatoicidae 29 45 20 Sphaeriidae 14 43 27 20 Rare Corixidae 100 100 57 55 77
Hydraenidae 30 29 14 27 26 Ancylidae 10 14 6 Hydrometridae 10 14 6 Corydalidae 9 3 Eustheniidae 14 3 Glossosomatidae 9 3 Heteroceridae 14 3 Hydrobiidae 14 3 Isostictidae 10 3 Muscidae 14 3 Odontoceridae 9 3 Pleidae 9 3 Psychodidae 9 3 Synlestidae 14 3
273
5.19.4 Ecosystem Health
The Murrumbidgee Valley river ecosystem was in Very Poor Health h (Lowland Zone: Poor; Slopes, Upland and Montane Zones: Very Poor). Fish abundance and biomass were dominated by alien species, and most expected species were absent. Many expected and disturbance- sensitive macroinvertebrate families were absent. The flow regime was typified by major changes in the magnitude of annual volumes and high flows, and in seasonality in the Murrumbidgee and Tumut Rivers, with little or no change from Reference Condition elsewhere.
Summary Theme assessments are as follows (Table MUR.7): Hydrology Theme
• Hydrology Index scores were 38–95, indicating Poor to Moderate Condition (Lowland Zone: Poor to Moderate, Slopes Zone Poor to Good). All tributaries in the Slopes Zone, and in the Lowland Zone except Yanco Creek, were Near Reference Condition. • Magnitude of high flows reduced by 25–63% relative to Reference Condition, and increased by 62–82% in the Tumut River. • A higher frequency of low flows than under Reference Condition, particularly in winter- spring. These events were less common in the Tumut, due to inter-valley transfers. • Variability downstream of Gundagai was reduced by 26–74% relative to Reference Condition, and by 23–51% in the Tumut River. • The Tumut at Odeys Bridge showed an Extreme Difference from Reference Condition in seasonality, with loss of its natural winter-spring flow pattern (the lowest score for the seasonality index of 469 assessed sites). The Murrumbidgee upstream of Burrinjuck was Near Reference Condition but the remaining sites showed Moderate to Large Differences. • Mean annual flow volume was reduced by 11–52% relative to Reference Condition, with the greatest reduction downstream of Balranald Weir; and doubled in the Tumut River. Median annual flows were reduced by up to 52% relative to Reference Condition, but increased in the Tumut River. Fish Theme • Condition Index SR–FI = 14 (CL 5–21), indicating Extremely Poor Condition, equal fifth-lowest among all Valleys. Condition varied among Zones (Lowland Zone: Poor; Slopes, Upland Zones: Extremely Poor; Montane Zone: Poor). • Twenty species caught, including seven alien species. • Predicted native species reduced in the Lowland (60%), Slopes (72%), Upland (83%) and Montane Zones (40%). • Mean abundance 55 fish per site, mainly alien species (71%). • Biomass overwhelmingly alien species (87%). Macroinvertebrate Theme • Condition Index SR–MI = 48 (CL 43–52), indicating Poor Condition (Lowland Zone: Moderate; Slopes and Upland Zones: Poor; Montane Zone: Very Poor). • Moderate diversity but low proportions of expected families in all Zones, especially the Montane Zone. • Moderate representation of expected disturbance-sensitive families in the Lowland and Montane Zones, but reduced in the Slopes and Upland Zones. 274
Table MUR.7: Murrumbidgee Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley. An ellipsis indicates no data (a Zone not identified for this Theme)
Zone
Valley Lowland Slopes Upland Montane
Hydrology Condition Poor to Poor to Poor ...... Rating Moderate Moderate to Good
14 (5–21) 0 (0–7) 0 (0–3) Fish Index 42 (23–50) 41 (31–49) Extremely Extremely Extremely Rating Very Poor Poor Poor Poor Poor
Macroinvertebrate Index 48 (43–52) 62 (51–71) 46 (36–49) 40 (31–52) 38 (29–47) Rating Poor Moderate Poor Poor Very Poor
Ecosystem Health Very Very Very Very Poor Rating Poor Poor Poor Poor 275
5.20 Namoi Valley
5.20.1 Hydrology
Figure NAM.1: Namoi Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Namoi Valley were 84–98, indicating Good Condition throughout.
The Namoi River rises in the Great Dividing Range and flows westward to join the Barwon River near Walgett. Its main tributary is the Peel River, joining the Namoi at Gunnedah. Other tributaries include the Manilla and McDonald Rivers and Coxs Creek. Smaller episodic tributaries meet the Namoi over much of its length. From Wee Waa to Walgett, the channel branches across a broad floodplain. There are major instream storages in the upper catchment, namely Keepit Dam on the Namoi (423 GL), Split Rock Dam at the junction of the Manilla and McDonald (397 GL) and Chaffey Dam on the Peel (62 GL). Weirs on the Namoi provide urban, stock and domestic supplies, and larger structures such as Mollee Weir and Gunidgera Weir provide irrigation water. Irrigation, mainly for cotton, occurs throughout the Valley. 276
Figure NAM.1 shows values of the Hydrology Index for five selected sites and Table NAM.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at all five selected sites was Near Reference Condition (SR–HI = 84–98). Of 22 sites examined in the Namoi system (data not shown here), only one, an Upland site on Dungowan Creek below Dungowan Dam, had a Hydrology Index <80 (SR–HI = 59). The indicators show:
• High-Flow Events: Magnitudes were Near Reference Condition at most sites, but with a decrease of up to 62% for lower Namoi sites. Site 1 showed a 62% decline from Reference Condition in high-flow magnitude, but little shift in median annual flows. Other sites were in Near Reference Condition. • Low- and Zero-Flow Events: Near Reference Condition for all except Site 3 which is influenced by an upstream dam and showed a Moderate Difference from Reference Condition. • Variability: Near Reference Condition for all sites. • Seasonality: Near Reference Condition for most sites not shown but a Moderate to Large Difference from Reference Condition for some sites on the Namoi and tributaries downstream of storages. Site 3 showed a Large Difference; Sites 2 and 5 showed a Moderate Difference. • Gross Volume: Near Reference Condition except Site 1, which showed a Moderate Difference from Reference Condition. Considering the extent of irrigated agriculture in the Namoi Valley, the values of indicators (and the Hydrological Condition Index) appear high. Even at the most downstream site (Site 1), however, GV showed only a Moderate Difference from Reference Condition (modelled current mean annual flow was only 21% less than modelled natural flow). Seasonality (S) showed the expected effects of regulation and seasonal releases. The annual pattern is bimodal, with flow maxima in January-February and July. Regulation accentuates the summer maximum. In general, the flow regime of the Namoi Valley was Near Reference Condition, but with changes in volume, seasonality and high flows at sites downstream of storages.
Table NAM.1: Namoi Valley: SR Hydrology Index and indicators. Sites are shown in Figure NAM.1. DS: downstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Namoi at Goangra Lowland 84 72 89 82 83 60 2 Namoi at Mollee Slopes 93 84 83 96 69 94 3 Namoi DS Keepit Dam Slopes 93 94 79 93 54 100 4 Peel at Piallamore Upland 97 82 90 95 81 99 5 Peel DS Chaffey Dam Upland 98 87 98 97 68 100 277
5.20.2 Fish
100 Good 80 81 69 Moderate 60 59 48 Poor 40 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure NAM.2: Namoi Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 278
The Namoi Valley fish community was in Poor Condition. Most predicted native species were found, but five alien species were abundant. Alien species were 61% of total biomass and 37% of total abundance.
Twenty eight sites in four Zones of the Namoi Valley were surveyed in January 2006, yielding 2,453 fish. Analyses showed a Large (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 59 (CL 48–63). • Expectedness showed a Large (+) Difference from Reference Condition. • Nativeness showed a Large (+) Difference from Reference Condition. • Across the Valley, 80% of predicted native species were recorded. Figure NAM.2 shows sampling sites, Zones and corresponding SR–FI values, and Table NAM.2 shows Index values, Indicators, Metrics and derived variables. Twelve native species were caught, with three alien species in the Lowland and Slopes Zones, four in Upland sites and five in the Montane Zone. The Namoi Valley showed a Large (+) Difference from Reference Condition (Lowland Zone: Large (–) Difference, Slopes Zone: Moderate (±) Difference, Upland Zone: Moderate (±) Difference, Montane Zone: Large (±) Difference). The Valley score was in the upper range of Fish Index values (four Valleys scored higher). Expectedness was low in the Lowland and Montane Zones (SR–Fe = 31–40). Nativeness was high in the Upland Zone (SR–Fn = 73) but less (SR–Fn = 53–55) in the other Zones, with very different proportions of native fish individuals and biomass among the Zones. Variability in the index and indicators within Zones was moderate. Overall, 80% of the Valley’s predicted native fish species were caught, although there were fewer records in the Lowland (42%) and Montane (50%) Zones. Only three of seven Lowland sites recorded more than two native species, while most sites in the Slopes Zone had four or more. Individual native fish were over half of the catch in each Zone, although the proportion of total biomass contributed by native species varied greatly, ranging from 91% in the Montane Zone to only 20% in the Slopes Zone, where large Carp were numerous. Moderate numbers of fish were caught (average 88 per site). The proportion of biomass contributed by native species was low (39%), but larger native fish such as Murray cod and Bony herring were recorded among large alien species that included Carp, Goldfish and trout. Medium- sized native fish including Spangled perch and River blackfish were common. Eastern gambusia were abundant. Murray cod were caught at two Montane Zone sites, where they were not predicted ; they probably were the result of stocking, and should be regarded as alien in that Zone. Table NAM.3 shows a summary of native species abundances. Freshwater catfish, Silver perch and Spangled perch were not caught at any sites in Zones where they were predicted to be common. Other species not caught in Zones where they were predicted to occur rarely or occasionally are also listed. Native Intolerant species were found in the Upland and Montane Zones only. Abnormalities were low, averaging 2.4% for the Valley. Mega-carnivores were common in all Zones.
279
Table NAM.2: Namoi Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone
Lowland Slopes Upland Montane Fish Index 59 (48–63) 40 (24–54) 69 (45–83) 81 (58–90) 48 (39–68) Expectedness Indicator 53 (42–60) 31 (23–46) 68 (41–79) 62 (53–72) 40 (40–55) Nativeness Indicator 61 (44–67) 56 (28–68) 56 (30–68) 92 (47–100) 55 (34–87) Metric Total species 17 8 11 13 8 Native species 12 5 8 9 3 Predicted RC–F species count 15 12 13 14 6 Alien species 5 3 3 4 5 Caught/Predicted native species (%) 80 42 62 64 50 Numbers of fish Mean fish per site 88 90 78 117 66 Native individuals (%) 63 52 79 58 69 Fish biomass Biomass/site all species (g) 6,484 5,337 13,856 3,387 3,355 Mean native biomass/fish (g) 46 72 45 15 67 Mean alien biomass/fish (g) 123 46 687 49 15 Biomass native (%) 39 63 20 29 91
280
Table NAM.3: Namoi Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes Upland Montane
Australian smelt 0 31 39 70 Bony herring 102 179 17 298 Carp gudgeons 212 112 218 10 552 Darling River hardyhead 0 38 0 38 Freshwater catfish 0 0 7 0 7 Golden perch 5 3 4 12 Mountain galaxias 127 259 386 Murray cod* 6 10 0 12 28 Murray–Darling rainbowfish 1 73 0 74 Olive perchlet 0 0 0 River blackfish 19 51 70 Silver perch 0 0 0 0 Southern purple-spotted gudgeon 0 0 0 0 0 Spangled perch 0 19 5 24 Un-specked hardyhead 0 6 0 6
Alien species
Brown trout 45 45 Carp 38 81 15 134 Eastern gambusia 238 28 311 43 620 Goldfish 25 4 17 5 51 Rainbow trout 1 37 38
* Not native in the Montane Zone, probably from hatchery stock 281
5.20.3 Macroinvertebrates
100 Good 80 Moderate 60 64 54 56 52 Poor 40 43 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure NAM.3: Namoi Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 282
The Namoi Valley macroinvertebrate community was in Poor Condition, with all Zone communities in Poor Condition except for the Lowland Zone, which was in Moderate Condition. Most communities had low diversity and lacked most of their disturbance–sensitive families.
Twenty five sites were surveyed across four Zones of the Namoi Valley in June 2005, yielding 5,480 macroinvertebrates in 73 families (50% of Basin families). Analyses indicate a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 52 (CL 48–57). • Moderate proportion of expected families (Filters OE = 30). • Reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 89). SR–MI for the Namoi Valley is in the mid–range of scores for all Valleys (cf. Broken, Darling, Loddon). The Slopes, Upland and Montane Zones showed Large (+) to Large (–) Differences from Reference Condition (SR–MI = 43–56), and the Lowland Zone showed a Moderate (±) Difference (SR–MI = 64). Wide confidence intervals for SR–MI in the Lowland and Montane Zones (36, 24 points) indicated substantial variation in condition among sites. Figure NAM.3 shows sampling sites, Zones and SR–MI values, and Table NAM.4 shows metrics and derived variables. Seventy two percent of expected families were recorded in the Valley. Family richness was less than Reference Condition at over 40% of sites. Diversity was moderate (average 24 families per site), with Montane Zone sites being most diverse (average 33 families per site). A moderate proportion (54%) of the Valley fauna occurred in the Lowland Zone, compared with 66–74% for other Zones. Table NAM.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families at 92% of sites (and stream length), with significant variation among sites in the Lowland Zone. Only two sites in the Valley had a low Filters OE score. Filters SIGNAL OE scores were reduced for all Zones, with lowest values in the Upland Zone. The communities in all Zones were impoverished and lacking disturbance-sensitive families. Table NAM.6 shows ‘common’ and ‘rare’ families. Six common families included freshwater shrimps (Atyidae), longhorned and ecnomid caddisflies (Leptoceridae, Ecnomidae) and velvet water bugs (Hebridae). Five ‘rare’ families included hawker and emerald dragonflies (Aeshnidea, Corduliidae) and midges (Chironominae). 283
Table NAM.4: Namoi Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 52 64 54 43 56 (48–57) (39–75) (48–59) (29–48) (46–70) Metrics Filters OE 30 37 31 26 33 (28–33) (22–41) (29–33) (19–28) (30–38) Filters SIGNAL OE 89 90 91 82 88 (84–92) (86–97) (82–95) (79–89) (79–98) Families Families per site 24 19 23 25 33 minimum – maximum 11–37 11–27 18–28 15–31 28–37 Total families 73 39 47 53 53
Table NAM.5: Namoi Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 25 8 7 7 3
Filters OE High 2 2 Medium 21 6 7 5 3 Low 2 2 Filters SIGNAL OE High Medium 21 8 6 5 2 Low 4 1 2 1
284
Table NAM.6: Namoi Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 8 7 7 3 25 Number of families sampled 41 50 56 55 76 Percent of families in Basin 35.7 38.2 47.9 52.4 50.0 Percent of families in Valley 54 66 74 72 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY
Common Corixidae 100 100 100 100 100 Leptoceridae 100 100 100 100 100 Atyidae 88 100 86 100 92 Ecnomidae 50 29 43 100 48 Hebridae 25 14 14 16 Diphlebiidae 29 8 Rare Chironominae 63 86 100 100 84 Corduliidae 14 43 33 20 Ostracoda 43 29 20 Aeshnidae 14 4 Calamoceratidae 33 4
285
5.20.4 Ecosystem Health
The Namoi Valley river ecosystem was in Poor Health (Lowland, Slopes and Upland Zones: Moderate; Montane Zone: Poor). Fish abundance was dominated by native species but biomass was dominated by aliens; several expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. The flow regime was Near Reference Condition, but with changes in volume, seasonality and high flows at sites downstream of storages.
Summary Theme assessments are as follows (Table NAM.7): Hydrology Theme • Condition Index SR–HI = 84–98 at selected mainstem locations, indicating Good Condition (all Zones: Good). • High-flows were Near Reference Condition for most sites, but with a reduction of up to 62% at lower Namoi River sites. • Incidence and duration of low and zero flows and flow variability were Near Reference Condition for all sites except Dungowan Creek. • Seasonality of flows was Near Reference Condition for most sites, but with Moderate to Large Differences at some Namoi River sites and tributaries below storages. • Annual flow volume indicator values were Near Reference Condition for all sites except Dungowan Creek. Fish Theme • Condition Index SR–FI = 59 (CL 48–63), indicating Poor Condition, but in the upper range of scores for all Valleys. Condition varied among Zones (Lowland Zone: Poor; Slopes, Upland Zones: Moderate; Montane Zone: Poor). • Seventeen species caught, including five alien species. • Predicted native species reduced in the Lowland (58%), Slopes (38%), Upland (36%) and Montane Zones (50%). • Mean abundance 88 fish per site, mainly native species (63%). • Biomass mainly alien species (61%). Macroinvertebrate Theme • Condition Index SR–MI = 52 (CL 48–57), indicating Poor Condition (Lowland Middle Zone: Moderate; other Zones: Poor). • High diversity in Montane Zone and moderate to low diversity in other Zones, and much- reduced proportions of expected families in all Zones. • Reduction of expected disturbance-sensitive families, especially in the Upland Zone. 286
Table NAM.7: Namoi Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes Upland Montane
Hydrology Condition Good Good Good Good Good Rating Fish Index 59 (48–63) 40 (24–54) 67 (45–83) 73 (58–90) 51 (39–68) and Rating Poor Poor Moderate Moderate Poor
Macroinvertebrate Index 52 (48–57) 64 (39–75) 54 (48–59) 43 (29–48) 56 (46–70) and Rating Poor Moderate Poor Very Poor Poor
Ecosystem Health Poor Moderate Moderate Moderate Poor Rating
287
5.21 Ovens Valley
5.21.1 Hydrology
Figure OVE.1: Ovens Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index values for the Ovens Valley were 81–100, indicating Good Condition throughout.
The two principal streams in the Ovens Valley are the Ovens and King Rivers. The Ovens rises near Mount Buffalo, flows northwest to Wangaratta thence north to join the Murray at Lake Mulwala, impounded by Yarrawonga Weir. The King rises near the Goulburn catchment and flows north to join the Ovens at Wangaratta. Other tributaries of the Ovens include the Buckland River, joining the Ovens in its Slopes Zone, and the Buffalo River and Reedy Creek, joining the Ovens near Wangaratta. Fifteen Mile Creek also joins downstream of Wangaratta. Between its junctions with the Buffalo and the King, the Ovens forms a number of anabranches across a wide floodplain, part-shared with the King. From this point to the Murray, the Ovens flows through a confined floodplain with anabranches and billabongs. There are two instream storages, Lake 288
Buffalo (24 GL) on the Buffalo and Lake William Hovell (14 GL) on the King, but they have little influence on the respective rivers. In the past there was extensive mining of alluvial gold, particularly in the Buckland River and Reedy Creek. Figure OVE.1 shows values of the Hydrology Index for five selected sites and Table OVE.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). At all selected sites, hydrological condition was Near Reference (SR–HI = 81–100). All 23 sites assessed in the Ovens Valley fell in this range. Individually, the indicators show:
• High-Flow Events All sites were Near Reference Condition. • Low- and Zero-Flow Events: Sites on the Ovens and King Rivers in the Lowland Zone (e.g. Sites 2, 4) showed a Large Difference from Reference Condition, mainly because in December to June the volume of the minimum monthly flow and the lowest 10th percentile monthly flow were reduced compared to modelled natural conditions. Site 1 showed a Moderate Difference; Sites 3 and 5 were Near Reference Condition. • Variability: All sites were Near Reference Condition. • Seasonality: All sites were Near Reference Condition. • Gross Volume: All sites were Near Reference Condition. Condition in both Slopes and Lowland Zones was Good, and presumed to be similar in the Upland and Montane Zones. Only one indicator, LZFE, showed a shortfall from Reference Condition, due to a reduction in the volume of summer (low) flows. The data imply that, for the Ovens and King Rivers:
• The extent of regulation is not sufficient to affect the natural seasonal pattern (high flows in winter-spring; low flows in summer-autumn). • The volume diverted is insufficient to change HFE or GV from ‘natural’. • There is a shortfall in LFZE at sites downstream of irrigation areas (Sites 2, 4), because the (unmodified) natural pattern of low flows in summer coincides with irrigation diversions that are insufficient to affect HFE and GV. In general, the flow regime of the Ovens Valley showed little change from Reference Condition, other than changes to low flows in the mid-Lowland Zone.
Table OVE .1: Ovens Valley: SR Hydrology Index and indicators. Sites are shown in Figure OVE .1. US: upstream
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Ovens Outlet lowland 94 98 69 95 92 100 2 Ovens US King junction lowland 89 100 58 96 93 100 3 Ovens US Myrtleford slopes 100 100 96 99 97 100 4 King Outlet lowland 81 99 42 94 93 100 5 King US Lake William Hovell upland 100 100 100 100 100 100 289
5.20.3 Fish
100 Good 80 Moderate 60 63 51 50 46 46 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure OVE.2: Ovens Valley: fish sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 290
The Ovens Valley fish community was in Poor Condition, with the Upland Zone community in Very Poor Condition. Only 59% of predicted native species were caught; these were only half of the total catch and a quarter of the biomass. The community had lost much of its native species richness and alien fish were abundant.
Communities in 26 sites across four altitudinal Zones of the Ovens Valley were surveyed in February and March 2007, yielding 1,975 fish. Analyses showed a Large (–) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 50 (CL 33–57). • Expectedness showed a Large (–) Difference from Reference Condition. • Nativeness showed a Large (±) Difference from Reference Condition. • Thirteen (59%) of the 22 predicted native species (RC–F) were recorded. • Native fish comprised only half (53%) of total catch and quarter (23%) of total biomass. Figure OVE.2 shows sampling sites, Zones and corresponding SR–FI values, and Table OVE.2 shows Index values, Indicators, Metrics and derived variables. Thirteen native and six alien species were caught in the Valley. The Ovens Valley showed a Large (–) Difference from Reference Condition (Lowland Zone: Large (–) Difference, Slopes Zone: Large (±) Difference, Upland Zone: Very Large (+) Difference, Montane Zone: Moderate (±) Difference). Only five sites could be sampled in the Montane Zone. The Valley Fish Index (SR–FI = 47) exceeded the average for the Basin (nine Valleys had higher scores). Condition was best in the Montane Zone (SR–FI = 60), where two of three predicted (RC–F) species were recorded, and poorest in the Upland Zone (SR–FI = 36), where there were three RC–F species from a predicted seven. The Lowland and Slopes Zones had intermediate scores of SR–FI = 45 and SR–FI = 46, respectively. Variability was apparent at sites in the three higher-altitude Zones, with substantial variation in Index and Nativeness scores. Fish were moderately abundant (average 76 per site) in all Zones. Native proportions of total biomass and abundance were similar, except for low abundance (27%) in the Slopes Zone and higher biomass (42%) in Upland sites, where 253 Two–spined blackfish were caught. Rainbow trout and Brown trout were the only alien species in Montane and Upland sites, but more were caught in the Slopes (five) and Lowland (four) Zones. Only 1–2 native species were recorded at Upland and Montane Zone sites, and two Montane Zone sites had no native fish. Table OVE.3 shows that significant numbers of several native species were recorded, including Trout cod, the two blackfish species and Murray cod. Among alien species, Eastern gambusia were sometimes abundant and there were moderate numbers of Redfin perch, Carp and the two trout species. No Macquarie perch, Mountain galaxias or Obscure galaxias, and only a single Southern pygmy perch, were caught in Zones where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Bony herring, Freshwater catfish, Silver perch, Golden perch and Trout cod, as well as several small, less well-known species Few Abnormalities (1.4%) were recorded. Five Intolerant species were caught. There were many Mega-carnivores in the Lowland Zone, few in the Slopes Zone and none elsewhere. 291
Table OVE.2: Ovens Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone
Lowland Slopes Upland Montane Fish Index 50 (33–57)46 (28–55)51 (24–66) 46 (21–54) 63 (30–80) Expectedness Indicator 48 (34–57)46 (28–49)46 (33–54) 37 (37–37) 72 (46–84) Nativeness Indicator 46 (26–61)40 (31–58)52 (19–92) 56 (13–74) 31 (0–49) Metric Total species 19 14 12 5 4 Native species 13 10 7 3 2 Predicted RC–F species count 22 22 14 7 3 Alien species 6 4 5 2 2 Caught/Predicted native species (%) 59 45 50 43 67 Numbers of fish Mean fish per site 76 92 106 47 52 Native individuals (%) 53 67 27 79 61 Fish biomass Biomass/site all species (g) 9,411 28,458 4,363 1,092 1,459 Mean native biomass/fish (g) 54 103 36 12 13 Mean alien biomass/fish (g) 203 718 43 65 52 Biomass native (%) 23 22 24 42 28
292
Table OVE.3: Ovens Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Zone Total Native species Lowland Slopes Upland Montane
Australian smelt 34 0 0 34 Bony herring 0 0 Carp gudgeons 275 0 275 Dwarf flat-headed gudgeon 0 0 Flat-headed gudgeon 56 0 56 Freshwater catfish 0 0 Riffle galaxias 0 1 1 7 9 Golden perch 4 0 4 Macquarie perch 0 0 0 0 Mountain galaxias 0 0 7 0 7 Murray cod 22 2 24 Flat-headed galaxias 0 0 0 Murray–Darling rainbowfish 0 0 Obscure galaxias 0 2 2 River blackfish 14 51 65 Short-headed lamprey 0 0 Silver perch 0 0 Southern purple-spotted gudgeon 0 0 Southern pygmy perch 1 5 0 6 Trout cod 16 1 0 17 Two–spined blackfish 6 141 253 151 551 Un-specked hardyhead 1 1
Alien species
Brown trout 4 27 53 84 Carp 83 7 90 Eastern gambusia 89 468 557 Goldfish 19 19 Rainbow trout 1 41 47 89 Redfin perch 25 60 85
293
5.21.2 Macroinvertebrates
100 Good 80 67 Moderate 60 57 57 51 Poor 40 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes upland montane
Figure OVE.3: Ovens Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 294
The Ovens Valley macroinvertebrate community was in Poor Condition. The Lowland, Slopes and Montane Zones were in Poor Condition; the Upland Zone was in Moderate Condition. Most sites were missing ‘expected’ families but retained most of their disturbance–sensitive families.
Thirty five sites were surveyed across four Zones of the Ovens Valley in December 2005, yielding 7,367 macroinvertebrates in 86 families (62% of Basin families). Analyses indicate a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 57 (CL 51–59). • Moderate to low proportion of expected families (Filters OE = 29). • SIGNAL OE score near Reference Condition (Filters SIGNAL OE = 102). SR–MI for the Ovens Valley is the sixth highest of all Valley scores (cf. Mitta Mitta, Gwydir). The Lowland, Slopes and Montane communities showed Large (–) to Large (+) Differences from Reference Condition (SR–MI = 51, 57, 40 respectively) and the Upland Zone showed a Moderate Difference (SR–MI = 67). The wide confidence interval for SR–MI in the Montane Zone (22 points) indicated substantial variation in condition among only three sampled sites. Figure OVE.3 shows sampling sites, Zones and SR–MI values, and Table OVE.4 shows metrics and derived variables. Eighty three percent of expected families were recorded in the Valley. Family richness was less than Reference Condition at over 40% of sites. Diversity was moderate to high (average 28 families per site), with Upland Zone sites having most diversity (average 33 families per site). A moderate proportion (60–77%) of the Valley fauna was in the Lowland to Upland Zones, compared to 38% for the Montane Zone. Table OVE.5 shows that Expected (Filters OE) scores indicated substantial loss of expected families. Only two sites in the Valley had a high Filters OE score, and four sites (11%) had a low Filters OE score. Filters SIGNAL OE scores were high (close to or at Reference Condition) for all Zones except the Lowland. The Upland Zone community was rated in best Condition. Most communities in the Valley were impoverished but had lost few of their disturbance-sensitive families. Table OVE.6 shows ‘common’ and ‘rare’ families. Nine common families included mayflies (Leptophlebiidae), three subfamilies of midges (Chironominae, Orthocladiinae, Aphroteniinae), water scavenger beetles (Hydrophilidae) and broad–shouldered water striders (Veliidae). The 15 rare families included a range of families normally found in lowland reaches. The apparent scarcity of palaemonids is noteworthy, as the prawn Macrobrachium australiense is common elsewhere in the Basin. 295
Table OVE.4: Ovens Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes Upland Montane
Index SR–MI 57 51 57 67 40 (51–59) (44–56) (49–61) (65–77) (26–48) Metrics Filters OE 29 27 29 31 20 (26–29) (24–31) (25–30) (30–35) (18–23) Filters SIGNAL OE 102 96 102 117 100 (98–107) (88–98) (98–104) (106–1.20) (79–107) Families Families per site 28 24 30 33 19 minimum – maximum 17–41 17–31 17–35 23–41 17–20 Total families 86 53 67 61 33
Table OVE.5: Ovens Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes Upland Montane
Number of sites 35 10 13 9 3
Filters OE High 2 1 1 Medium 29 7 12 8 2 Low 4 2 1 1 Filters SIGNAL OE High 18 8 9 1 Medium 13 8 4 1 Low 4 2 1 1
296
Table OVE.6: Ovens Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 10 13 9 3 35 Number of families sampled 53 68 61 33 88 Percent of families in Basin 48.6 55.7 54.5 33.3 61.5 Percent of families in Valley 60 77 69 38 100
Percent of sites by Zone Lowland Slopes Upland Montane VALLEY
Common Chironominae 100 100 100 100 100 Leptophlebiidae 90 100 100 100 97 Orthocladiinae 100 92 100 100 97 Veliidae 100 100 78 67 91 Hydrophilidae 90 85 56 100 80 Calamoceratidae 40 38 78 46 Dixidae 20 46 56 33 40 Synlestidae 54 33 29 Aphroteniinae 22 6 Rare Palaemonidae 30 9 Ceinidae 10 3 Gordiidae 8 3 Helicophidae 11 3 Libellulidae 11 3 Lymnaeidae 8 3 Megapodagrionidae 11 3 Mesoveliidae 10 3 Nannochoristidae 33 3 Naucoridae 10 3 Neoniphargidae 33 3 Nevrothidae 10 3 Odontoceridae 8 3 Pelecypoda 8 3 Richardsonianidae 8 3
297
5.21.3 Ecosystem Health
The Ovens Valley river ecosystem was in Poor Health (Lowland and Slopes Zones: Poor; Upland Zone: Very Poor; Montane Zone: Moderate). Fish abundance dominated by native species, but biomass dominated by aliens and several expected species were absent. Many expected and several disturbance-sensitive macroinvertebrate families were absent. The flow regime showed little change from Reference Condition, other than changes to low flows in the Lowland Zone.
Summary Theme assessments are as follows (Table OVE.7): Hydrology Theme • Condition Index scores for the Ovens and King Rivers were 81–100, indicating Good Condition. Both Lowland and Slopes Zones were in Good Condition. • The magnitude of high flows and mean and median annual volumes, variability and seasonality were all Near Reference Condition. • Sites in the Lowland Zone of the Ovens and King Rivers showed a Large Difference from Reference Condition in the incidence and duration of low and zero flows, mainly due to changes in the magnitude of low flows. Fish Theme • Condition Index SR–FI = 50 (CL 33–57), indicating Poor Condition but above average (SR–FI = 37) for all Valleys. Condition varied among Zones (Lowland, Slopes Zones : Poor, Upland Zone: Extremely Poor; Montane Zone: Moderate). • Nineteen species caught, including six alien species. • Predicted native species reduced in the Lowland (55%), Slopes (50%), Upland (57%) and Montane Zones (33%). • Mean abundance 76 fish per site, mainly native species (53%). • Biomass mainly alien species (77%). Macroinvertebrate Theme • Condition Index SR–MI = 57 (CL 51–59), indicating Poor Condition (Lowland and Slopes Zones: Poor; Upland and Montane Zones: Moderate). • Moderate to high diversity but low proportions of expected families in all Zones, especially the Montane Zone. • Moderate representation of expected disturbance-sensitive families, especially in the Upland Zone. 298
Table OVE.7: Ovens Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower – upper 95% confidence limits). For Hydrology there are no aggregated index values and the ratings are not strictly representative of Zones or the Valley.
Zone
Valley Lowland Slopes Upland Montane
Hydrology Condition Good Good Good Good Good Rating
36 (21–54) Fish Index 50 (33–57) 45 (28–55) 46 (24–66) 60 (30–80) Extremely Rating Poor Poor Poor Moderate Poor
Macroinvertebrate Index 57 (51–59) 51 (44–56) 57 (49–61) 67 (65–77) 40 (26–48) Rating Poor Poor Poor Moderate Poor
Ecosystem Health Poor Poor Poor Moderate Moderate Rating
299
5.22 Paroo Valley
5.22.1 Hydrology
Figure PAR.1: Paroo Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores (SR–HI) for the Paroo were 100, indicating Near Reference Condition.
The Paroo is the most north-westerly Valley in the Murray-Darling Basin, covering 36,000 km2 or nearly 3.5% of the Basin area. It is an episodic stream, and at the Wanaaring gauge (Site 1), the furthest point downstream where gauging is possible, there is no flow for about 37% of the time. Beyond this point the river dissipates into a large deflation area, the Paroo Overflow, which contains significant wetlands. Water rarely proceeds from this area to the Darling. There is little diversion from the Paroo (about 4 GL/y) and no instream storages. Most of the Valley has access to the Great Artesian Groundwater Basin. Figure PAR.1 shows the value of the Hydrology Index, SR–HI, at four sites and Table PAR.1 shows the index and indicator values. These sites provide examples of hydrological conditions in 300 the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). All four sites were in Near Reference Condition (SR_HI = 100). The indicators show:
• High-Flow Events: Near Reference Condition at all sites. • Low- and Zero-Flow Events: Preserved throughout though with slight reduction at Willara Crossing (Site 2). • Variability: Preserved at all sites. • Seasonality: All values were Near Reference Condition with only slight change observed in the two downstream sites. • Gross Volume: Near Reference Condition at all sites. Very high values of both the index and the indicators suggest that flow in the Paroo is little changed from the natural regime.
Table PAR.1: Paroo Valley: SR Hydrology Index and indicators. Sites are shown in Figure PAR.1.
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Paroo River at Wanaaring Lowland 100 100 100 100 98 100 Paroo River at Willara Lowland 2 100 100 93 100 98 100 Crossing 3 Paroo River at Caiwarro Lowland 100 100 100 100 100 100 4 Paroo River at Yarronvale Lowland 100 100 100 100 100 100
301
5.22.2 Fish
100 Good 80 78 78 Moderate 60 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland
Figure PAR.2: Paroo Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 302
The Paroo Valley fish community was in Moderate Condition. Nativeness was extremely high but only 58% of predicted native species were caught, resulting in low Expectedness. The community had lost much of its native species richness.
Paroo Valley communities were surveyed in April–May 2006. Eighteen sites were sampled in the Lowland Zone (the only altitudinal Zone) and 1,047 fish were caught. Analyses showed a Moderate (+) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 78 (CL 76–91). • Expectedness showed a Large (+) Difference from Reference Condition. • Nativeness was near Reference Condition. • Native fish comprised a high proportion (78%) of total biomass. Figure PAR.2 shows sampling sites, Zones and corresponding SR–FI values, and Table PAR.2 shows Index values, Indicators, Metrics and derived variables. The Paroo Valley community showed a Moderate (+) Difference from Reference Condition. The Valley had the highest Fish Index score among all Valleys (next highest was the Condamine: SR–FI = 63). Almost all captured fish (97%) were native to the Valley, although a few individuals of three alien species were recorded. Nevertheless, five of 12 predicted native species were not found, resulting in an Expectedness score (SR–Fe = 59) much lower than the Nativeness score (SR–Fn = 99). These two indicators and the Fish Index showed only slight variability, indicating uniform conditions among sites. All but 3% of individual fish were native to the Valley, and native biomass was a relatively high 78%. The few alien fish were substantially larger (84 g per fish) than the small native species (10 g per fish). Most sites yielded 3–4 native species. Bony herring were widespread and abundant, and Golden perch, Murray–Darling rainbowfish, Spangled perch and Hyrtl's tandan also were widespread, in smaller numbers. Carp and Goldfish were sparsely distributed and in low abundance. Only one Eastern gambusia was caught. Table PAR.3 shows that a single Carp gudgeon was caught, although these small species were predicted in the RC–F list to occur commonly. Species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Murray cod, Freshwater catfish and some small, less well–known species. Abnormalities were recorded in 3.2% of fish. Mega-carnivores were common. Intolerant species were not found. 303
Table PAR.2: Paroo Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Lowland Valley Zone
Fish Index 78 (76–91) 78 (76–91) Expectedness Indicator 59 (56–73) 59 (56–73) Nativeness Indicator 99 (90–100) 99 (90–100) Metric Total species 10 10 Native species 7 7 Predicted RC–F species count 12 12 Alien species 3 3 Caught/Predicted native species (%) 58 58 Numbers of fish Mean fish per site 58 58 Native individuals (%) 97 97 Fish biomass Biomass/site all species (g) 751 751 Mean native biomass/fish (g) 10 10 Mean alien biomass/fish (g) 84 84 Biomass native (%) 78 78
304
Table PAR.3: Paroo Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Lowland Zone Total
Australian smelt 0 0 Bony herring 790 790 Carp gudgeons 1 1 Desert rainbowfish 0 0 Freshwater catfish 0 0 Golden perch 84 84 Hyrtl's tandan 11 11 Murray cod 0 0 Murray–Darling rainbowfish 67 67 Olive perchlet 0 0 Silver perch 1 1 Southern purple-spotted gudgeon 0 0 Spangled perch 57 57
Alien species
Carp 25 25 Eastern gambusia 1 1 Goldfish 10 10 305
5.22.3 Macroinvertebrates
100 Good 80 Moderate 60 64 64 Poor 40 Very Poor 20 Extremely Poor 0 Valley Lowland
Figure PAR.3: Paroo Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 306
The Paroo Valley macroinvertebrate community was in Moderate Condition. Most sites retained their ‘expected’ families, but were lacking disturbance–sensitive families, owing to drought.
Thirty five sites were surveyed across the Paroo Valley in June 2006, yielding 5,121 macro- invertebrates in 42 families (31% of Basin families). Analyses indicate a Minor difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 64 (CL 58–72). • Moderate proportion of expected families (Filters OE = 36). • Low SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 94). SR–MI for the Paroo Valley (which contains only one (Lowland) Zone) was the third highest score for all Valleys, equal to that of the Border Rivers and Upper Murray Valleys. The confidence interval for SR–MI (14 points) indicated reasonably consistent Condition among sites. Figure PAR.3 shows sampling sites, Zones and SR–MI values, and Table PAR.4 shows metrics and derived variables. Nearly all (93%) of expected macroinvertebrate families were recorded in the Valley. Family richness at site level was comparable to or slightly reduced compared to Reference Condition. Diversity was low to moderate (average 15 families per site). Table PAR.5 shows that Expectedness (Filters OE) and Filters SIGNAL OE scores were relatively high and near Reference Condition, with slight variation among sites. Eleven sites in the Valley (31% of stream length) had a high Filters OE score, and only one site had a low score. Filters SIGNAL OE scores were high at five sites (14%), and slightly to moderately reduced at the remainder. Most communities were only slightly impaired, and reduced Filters SIGNAL OE scores may be a result of the sustained dry conditions prior to sampling leading to reduced habitat quality. Table PAR.6 shows ‘common’ and ‘rare’ families. Nine common families included diving and water scavenger beetles (Dytiscidae), clam shrimps (Conchostraca), emerald dragonflies (Corduliidae) and midges (Chironominae, Tanypodinae). Clam shrimps are typical of temporary rain-water pools rather than permanent habitats. The 16 rare families included crustaceans (Anostraca, Atyidae, Corallanidae), longhorn caddis (Leptoceridae) and pond damselflies (Coen- agrionidae). 307
Table PAR.4: Paroo Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland
Index SR–MI 64 64 (58–72) (58–72) Metrics Filters OE 36 36 (33–39) (33–39) Filters SIGNAL OE 94 94 (91–97) (91–97) Families Families per site 15 15 minimum – maximum 9–23 9–23 Total families 42 42
Table PAR.5: Paroo Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland
Number of sites 35 35
Filters OE High 11 11 Medium 23 23 Low 1 1 Filters SIGNAL OE High 5 5 Medium 30 30 Low
308
Table PAR.6: Paroo Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 35 35 Number of families sampled 44 44 Percent of families in Basin 30.8 30.8 Percent of families in Valley 100 100
Percent of sites by Zone Lowland VALLEY
Common Chironominae 100 100 Corixidae 100 100 Tanypodinae 100 100 Dytiscidae 97 97 Hydraenidae 80 80 Hydrophilidae 80 80 Corduliidae 51 51 Temnocephalidea 34 34 Conchostraca 9 9 Rare Leptoceridae 60 60 Oligochaeta 34 34 Veliidae 17 17 Baetidae 6 6 Coenagrionidae 6 6 Noteridae 6 6 Orthocladiinae 6 6 Staphylinidae 6 6 Aeshnidae 3 3 Anostraca 3 3 Atyidae 3 3 Corallanidae 3 3 Ephydridae 3 3 Hirudinea 3 3 Paratelphusidae 3 3 Richardsonianidae 3 3
309
5.22.4 Ecosystem Health
The Paroo Valley river ecosystem was in Good Health. Fish abundance and biomass were dominated by native species and few aliens were recorded, although some expected species were absent. Most expected and disturbance-sensitive macroinvertebrate families were present. The flow regime generally was unaltered from Reference Condition.
Summary Theme assessments are as follows (Table PAR.7): Hydrology Theme • Condition Index SR–HI = 100 at selected mainstem locations, indicating Near Reference Condition. • All indicator scores were Near Reference Condition. Fish Theme • Condition Index SR–FI = 78 (CL 76–91), indicating Moderate Condition. This was the highest of scores for all Valleys. • Ten species caught, including three alien species. • Predicted native species reduced in the Lowland Zone (42%) • Mean abundance 58 fish per site, overwhelmingly native species (97%). • Biomass mainly native species (78%). Macroinvertebrate Theme • Condition Index SR–MI = 64 (CL 58–72), indicating Moderate Condition. • Low to moderate diversity, moderate to high proportions of expected families at all sites. • Disturbance-sensitive families well-represented.
Table PAR.7: Paroo Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland
Hydrology Condition Good Good Rating Fish Index 78 (76–91) 78 (76–91) Rating Moderate Moderate
Macroinvertebrate Index 64 (58–72) 64 (58–72) Rating Moderate Moderate
Ecosystem Health Good Good Rating 310
5.23 Warrego Valley
5.23.1 Hydrology
Figure WAR.1: Warrego Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Warrego Valley were 93–100, indicating Good Condition overall. Lowland reaches of the Warrego have experinced some changes in high flow and median annual volumes and duration of zero flow events compared to Reference Condition.
The Warrego, near the Warrego and Chesterton Ranges in the northern part of the Basin, and its Valley covers more than 74,000 km2 or 7% of the Basin area. The headwater streams converge around Augathella and Charleville and flow southward as the Warrego, to meet the Darling downstream of Bourke. Downstream of Cunnamulla the river breaks into distributaries, some of feeding the Yantabulla swamp in the Cuttaburra Basin, and it may deliver flood flows to the Paroo system. Water reaches the Darling from the Warrego only during flood conditions. At the southernmost gauging station, Site 1 at Ford’s Bridge (some 87 km from the Darling confluence), there is zero flow for about half the time. There are no instream storages other than weirs used for 311 stock and domestic supply. At Cunnamulla, the Allan Tannock Weir may divert water for local cotton irrigation. Figure WAR.1 shows the value of the Hydrology Index, SR–HI, for five selected sites and Table WAR.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Condition at the five sites assessed was Near Reference (SR–HI = 93 to 100). The indicators show:
• High-Flow Events: All sites were Near Reference Condition, with reduction by 14 and 19 % in high flow magnitudes at the most downstream sites (Fords Bridge and Barringun, respectively). • Low- and Zero-Flow Events: All sites were Near Reference Condition with the exception of the most downstream Warrego River site, at Fords Bridge, where the duration of zero flow events was substantially changed. The magnitude of low flow events was Near Reference at all sites. • Variability: All sites were Near Reference Condition. • Seasonality: All sites were Near Reference Condition. • Gross Volume: All sites were Near Reference Condition except the Warrego River at Fords Bridge. No sites had experienced significant changes in mean annual flow volumes compared to Reference Condition. However, both lowland Warrego River sites as well as the site at Wyandra had median annual volumes reduced by between 67 and 33% compared to Reference Condition. The Warrego at Fords Bridge was the most affected, with median volumes 33% of Reference Condition values.. The values suggest that the flow regime in the Warrego Slopes Zone was little changed from the natural regime, and that overall the seasonality, mean annual volume, variability and magnitude of high flows are also little changed from Reference Condition. However, the lower Warrego, as represented by the site at Fords Bridge, has experienced declines in high flow and median annual volumes, as well as a notable change in the duration of zero flow events..
Table WAR.1: Warrego Valley: SR Hydrology Index and indicators. Sites are shown in Figure WAR.1.
Indicators Site Location Zone SR–HI HFE LZFE V S GV
1 Warrego at Fords Bridge Lowland 93 86 78 91 92 60 2 Warrego at Barringun Lowland 98 82 100 95 96 84 3 Warrego at Cunnamulla Slopes 100 95 100 97 99 88 4 Warrego at Wyandra Slopes 100 99 99 99 98 86 5 Warrego at Augathella Slopes 100 100 100 100 100 100
312
5.23.2 Fish
100 Good 80 67 Moderate 60 56 51 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure WAR.2: Warrego Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 313
The Warrego Valley fish community was in Poor Condition, and only half of the predicted native species were recorded. Native fish were numerically dominant, but alien species dominated the biomass.
Fish communities in the Warrego Valley were surveyed in April–May 2006. Sixteen sites were sampled across two Zones, yielding 1,126 fish. Analyses showed a Large (–) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 56 (CL 17–58). • Expectedness showed a Very Large (+) Difference from Reference Condition. • Nativeness showed a Large (±) Difference from Reference Condition. • Only half of the Valley’s predicted native fish species were found. Figure WAR.2 shows sampling sites, Zones and corresponding SR–FI values, and Table WAR.2 shows Index values, Indicators, Metrics and derived variables. The Warrego Valley overall showed a Large (–) Difference from Reference Condition (Lowland Zone: Large (-) Difference, Slopes Zone: Moderate (–) Difference). Because drought made many sites unsuitable for sampling, only 16 sites could be surveyed. The Valley Fish Index score was near the average for the Basin. The Slopes Zone community had high Nativeness and was in substantially better condition than the Lowland Zone. Considerable variation was evident among sites in the Lowland Zone, especially in Nativeness. Only 36% and 54% of predicted RC–F species were recorded from the Lowland and Slopes Zones, respectively, and each had three alien species. The absence of half the RC–F species, and the low representation of alien species, resulted in Expectedness showing a Very Large Difference from Reference Condition, and Nativeness being somewhat higher. Although nearly all individual fish were native species, native biomass was only 52% of the total due to the larger average size of alien species (533 g) compared to native fish (31 g). Small (presumably juvenile) individuals dominated the native fish populations. Bony herring, Golden perch and Australian smelt were widespread and abundant in the Warrego Valley. Most sites had 3–4 native species. Carp gudgeons and Murray–Darling rainbowfish were recorded occasionally, as were Spangled perch and Murray cod. Carp were widespread and Goldfish and Eastern gambusia were caught occasionally. Table WAR.3 shows that Freshwater catfish, Silver perch and Spangled perch were not caught at any sites in Zones where they were predicted to be common. Other species not caught, but predicted to occur rarely or occasionally under Reference Condition, included Hyrtl’s tandan, Murray cod and some small, less well-known species. There were high levels of Abnormalities (5%), especially in the Slopes Zone. No Intolerant species were caught, but there were substantial numbers of Mega-carnivores.
314
Table WAR.2: Warrego Valley: Index, Indicators, Metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes
Fish Index 56 (17–58) 51 (7–55) 67 (56–70) Expectedness Indicator 37 (21–45) 32 (17–43) 50 (45–50) Nativeness Indicator 79 (20–80) 79 (9–78) 79 (62–99) Metric Total species 10 8 10 Native species 7 5 7 Predicted RC–F species count 14 14 13 Alien species 3 3 3 Caught/Predicted native species (%) 50 36 54 Numbers of fish Mean fish per site 70 57 84 Native individuals (%) 95 96 94 Fish biomass Biomass/site all species (g) 3,999 1,946 6,053 Mean native biomass/fish (g) 31 13 43 Mean alien biomass/fish (g) 533 578 515 Biomass native (%) 52 37 56
315
Table WAR.3: Warrego Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Native species Zone Total Lowland Slopes
Australian smelt 95 65 160 Bony herring 311 467 778 Carp gudgeons 7 12 19 Desert rainbowfish 0 0 Freshwater catfish 0 0 0 Golden perch 20 52 72 Hyrtl's tandan 0 0 0 Murray cod 0 1 1 Murray–Darling rainbowfish 4 18 22 Olive perchlet 0 0 0 Silver perch 0 0 0 Southern purple-spotted gudgeon 0 0 0 Spangled perch 0 16 16 Un-specked hardyhead 0 0 0
Alien species
Carp 11 27 38 Eastern gambusia 4 3 7 Goldfish 2 11 13 316
5.23.3 Macroinvertebrates
100 Good 80 Moderate 60 58 49 46 Poor 40 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure WAR.3: Warrego Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 317
The Warrego Valley macroinvertebrate community was in Poor Condition throughout. Both Lowland and Slopes Zones communities had few expected and disturbance-sensitive families.
Thirty five sites were surveyed across two Zones of the Warrego Valley in April 2006, yielding 4,086 macroinvertebrates in 45 families (33% of Basin families). Analyses indicate a Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 49 (CL 39–53). • Moderate proportion of expected families (Filters OE = 27). • Reduced SIGNAL OE score relative to Reference (Filters SIGNAL OE = 91). SR–MI for the Warrego Valley is in the lower mid–range of scores, near those for the Murrumbidgee and Macquarie. The Lowland and Slopes Zone communities showed Large Differences from Reference Condition (SR–MI = 46, 58, respectively). Confidence intervals for SR–MI in both Zones indicate substantial variation in condition among sites, especially in the Slopes Zone. Figure WAR.3 shows sampling sites, Zones and SR–MI values, and Table WAR.4 shows metrics and derived variables. Most (82%) of the expected families were recorded in the Valley. Family richness was significantly less than Reference Condition at all sites. Diversity was low (average 13 families per site), especially at Lowland Zone sites (average 12 families per site). Most (77–89%) of the Valley fauna was fond in both Zones. Table WAR.5 shows that Expected (Filters OE) scores indicated substantial losses of expected families, with some variation among sites. Only one site had a high Filters OE score, and nine (26%) had a low Filters OE score. Filters SIGNAL OE scores were reduced in both Zones. The Lowland Zone had the lowest Filters SIGNAL OE score, and eight sites (23%) had a much- reduced Filters SIGNAL OE score. Most communities (89% of stream length) were impoverished and missing some disturbance-sensitive families. Table WAR.6 shows ‘common’ and ‘rare’ families. Six common families included waterboatmen (Corixidae), mosquitoes (Culicidae), Small water beetles and variegated mud-loving beetles (Hydraenidae, Heteroceridae) and, in the Lowland Zone, clam shrimps (Conchostraca) and leeches (Richardsonianidae). The 21 ‘rare’ families included aquatic insect families (caddis, mayflies, beetles, damselflies, midges), including bugs (Veliidae, Mesoveliidae) and water measurers (Hydrometridae), and snails (Viviparidae, Planorbidae). 318
Table WAR.4: Warrego Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Index SR–MI 49 46 58 (39–53) (30–50) (52–72) Metrics Filters OE 27 26 32 (22–30) (19–28) (28–39) Filters SIGNAL OE 91 88 96 (87–95) (85–94) (92–97) Families Families per site 13 12 18 minimum – maximum 1–26 1–19 13–26 Total families 45 39 36
Table WAR.5: Warrego Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes
Number of sites 35 27 8
Filters OE High 1 1 Medium 25 18 7 Low 9 9 Filters SIGNAL OE High 4 4 Medium 23 15 8 Low 8 8
319
Table WAR.6: Warrego Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 27 8 35 Number of families sampled 42 36 47 Percent of families in Basin 38.5 29.5 32.9 Percent of families in Valley 89 77 100
Percent of sites by Zone Lowland Slopes VALLEY
Common Corixidae 100 100 100 Hydraenidae 78 88 80 Culicidae 44 100 57 Heteroceridae 11 25 14 Conchostraca 11 9 Richardsonianidae 11 9 Rare Chironominae 81 100 86 Leptoceridae 44 63 49 Caenidae 41 38 40 Acarina 37 38 37 Veliidae 11 100 31 Baetidae 7 88 26 Atyidae 15 11 Coenagrionidae 7 25 11 Gerridae 4 38 11 Scirtidae 4 38 11 Ancylidae 7 6 Ecnomidae 7 6 Orthocladiinae 7 6 Planorbidae 7 6 Tipulidae 4 13 6 Gyrinidae 4 3 Hebridae 4 3 Hydrometridae 13 3 Mesoveliidae 13 3 Viviparidae 13 3
320
5.23.4 Ecosystem Health
The Warrego Valley river ecosystem was in Poor Health (Lowland Zone: Poor; Slopes Zone: Moderate). Fish abundance and biomass were dominated by native species, although several expected species were absent. Many expected and some disturbance-sensitive macroinvertebrate families were absent. The flow regime was little changed from Reference Condition.
Summary Theme assessments are as follows (Table WAR.7): Hydrology Theme • Condition Index SR–HI = 93-100 at selected sites, indicating Near Reference Condition. • Most indicator scores were Near Reference Condition for most sites. • Median annual volumes were depressed by 33 – 67% for four of the five sites, but mean volumes were Near reference Condition. • The two downstream sites (Warrego at Fords Bridge) showed 14 – 19% declines in high flow magnitudes, and substantial changes in median annual volumes and duration of zero flow events. Fish Theme • Condition Index SR–FI = 56 (CL 17–58), indicating Poor Condition, but above the average (SR–FI = 37) for all Valleys. Condition varied between Zones (Lowland Zone: Poor; Slopes Zone: Moderate). • Ten species caught, including three alien species. • Predicted native species reduced in the Lowland (64%) and Slopes Zones (46%). • Mean abundance 70 fish per site, overwhelmingly native species (95%). • Biomass mostly native species (52%). Macroinvertebrate Theme • Condition Index SR–MI = 49 (CL 39–53), indicating Poor Condition (both Zones: Poor). • Low diversity, especially in the Lowland Zone, and low to very low proportions of expected families across both Zones. • Reduced and moderate representation of disturbance-sensitive families in the Lowland and Slopes Zones, respectively.
321
Table WAR.7: Warrego Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes
Hydrology Condition Good Good Good Rating Fish Index 56 (17–58) 32 (7–55) 66 (56–70) Rating Poor Very Poor Moderate
Macroinvertebrate Index 49 (39–53) 46 (30–50) 58 (52–72) Rating Poor Poor Poor
Ecosystem Health Poor Poor Moderate Rating 322
5.24 Wimmera Valley
5.24.1 Hydrology
Figure WIM.1: Wimmera Valley: Hydrology assessment sites coloured by SR Hydrology Index scores (see key)
Hydrology Index scores for the Wimmera Valley were 39–100, indicating Poor Condition (Lowland Zone: Poor to Very Poor Condition; Slopes Zone: Good Condition).
Streams of the Wimmera Valley form a complex network, terminating inland. The Wimmera River terminates in a series of important wetlands including Ramsar-listed sites at Lakes Hindmarsh and Albacutya. The Wimmera is highly regulated, with seven large storages (>15 GL) on tributaries but only one small storage, Mount Cole Dam, on the main channel. Approximately 120 GL of surface water is diverted annually for irrigation, but there is significant transmission loss and only about 40 GL is applied as irrigation water. Piping is being developed as an efficiency measure. Inter-basin diversions from the south-flowing Glenelg River are piped into the Wimmera Valley. 323
Figure WIM.1 shows the value of the Hydrology Index, SR–HI, for five selected sites and Table WIM.1 shows the index and indicator values. These sites provide examples of hydrological conditions in the main streams of the Valley. They are not a statistically representative sample, nor do they support statistical/numerical aggregation of data to Zone- or Valley-scales (see further Section 3.2.5). Sites 1-4 are on the Wimmera mainstem. Site 5 is on Yarriambiack Creek, a north-flowing distributary stream that terminates at Lake Coorong. In the Wimmera, the Hydrology Index (SR– HI) ranges from 100 upstream to 39 at the most downstream site, spanning the range from Near Reference Condition to a Very Large Difference from Reference Condition. Yarriambiack Creek is in Near Reference Condition (SR–HI = 88). The indicators show:
• High-Flow Events: Reduced by up to 60% in the Wimmera Lowland Zone. Most Lowland Zone tributaries were Near Reference Condition, although several showed reductions of 20–95%. Most Slopes Zone sites were Near Reference Condition. Reductions at down- stream Sites 1–2 reflect irrigation diversions. • Low- and Zero-Flow Events: Near Reference Condition in nearly all Slopes and most Lowland Zone sites, and reduced by 45-95% or more in downstream reaches of the Lowland Zone. • Variability: Reduced by 40% in the lowest reaches, Near Reference Condition elsewhere. • Seasonality: The least-changed of the five indicators. Moderate to Large Differences changes throughout, but most changed at Site 5. • Gross Volume: Mean and median annual flow volumes were substantially less than Reference Condition at many sites, by 45-60% and 85-95%, respectively, in the lower Wimmera. Low values, particularly in the Lowland Zone (Sites 1, 2, 5), reflect bulk removal of water for irrigation. Reductions of 10-85% and up to 60% were observed for mean and median annual flow volumes, respectively, in most Slopes Zone sites. The progressive decline of GV along the river reflects the cumulative effect of diversions. The shortfall at the upstream site (Site 4) may reflect the effect of large farm dams rather than diversions from the river. The change in LZFE in the lower reaches is potentially of ecological concern. In general, the flow regime of the Wimmera Valley was highly modified, with reduced high flow magnitudes, annual volumes and Variability, mainly in the lower reaches. The frequency and volume of discharge to the terminal lakes also were significantly reduced.
324
Table WIM.1: Wimmera Valley: SR Hydrology Index and indicators. Sites are shown in Figure WIM.1. US: upstream; DS: downstream
Indicators Site Location SR–HI HFE LZFE V S GV
1 Wimmera US Lake Hindmarsh 39 43 0 60 75 34 2 Wimmera US Dimboola 50 43 44 62 67 33 3 Wimmera at Glenorchy 98 98 94 92 81 75 4 Wimmera DS Elmhurst 100 100 95 98 97 86 5 Yarriambiack Creek at Kellalac 88 80 99 92 62 48 325
5.24.2 Fish
100 Good 80 84 Moderate 60 47 Poor 40 Very Poor 20 23 Extremely Poor 0 Valley lowland slopes
Figure WIM.2: Wimmera Valley: sampling sites and Zones coloured by SR Fish Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 326
The Wimmera Valley fish community was in Poor Condition, with the Lowland Zone in Very Poor Condition but the Slopes Zone in Near Reference Condition. Most predicted native species were found, but they were only a tenth of total biomass. The community had lost native species richness and alien and introduced fish were common.
Fish communities in 17 sites across two Zones (Lowland: eight sites, Slopes: nine sites) of the Wimmera Valley were surveyed in November 2006 and January 2007, yielding 1,009 fish. Analyses showed a Large (–) Difference from Reference Condition:
• SR Fish Index (SR–FI) = 47 (CL 36–57). • Expectedness showed a Large (+) Difference from Reference Condition. • Nativeness showed a Very Large (+) Difference from Reference Condition. • Five (83%) of the six predicted native species (RC–F) were recorded. • Although 64% of fish were native, they contributed only 11% of total biomass. Figure WIM.2 shows sampling sites, Zones and corresponding SR–FI values, and Table WIM.2 shows Index values, Indicators, Metrics and derived variables. Five native and eight alien species were recorded. The Valley showed a Large (–) Difference from Reference Condition (Lowland Zone: Very Large (±) Difference, Slopes Zone: Near (–) Reference). The Wimmera Valley Fish Index was in the upper range of scores for the Basin (eight of the 23 Valleys had higher scores). Condition was far better in the Slopes Zone (SR–FI = 83) than the Lowland Zone (SR–FI = 28), where only two of six RC–F species were caught. Moderate variability was apparent in communities in both Zones, mostly through variations in Nativeness. Fish were abundant (average 59 per site), with similar numbers in each Zone. Native proportions of total fish biomass and total abundance were much higher in the Slopes Zone, but similar numbers of alien species were present in both Zones. Only 1–2 native species were recorded at individual Lowland sites, whereas the numbers of native species at Slopes Zone sites varied substantially (one site had neither alien nor native fish; others had 2–4 native species). Table WIM.3 shows that few popular native species were recorded (eight River blackfish, six introduced Golden perch). Two small native fish, Flat-headed gudgeon and Southern pygmy perch, were particularly abundant. Common galaxias were numerous, having been introduced through inter–basin water transfers between the Wimmera and Glenelg rivers. Golden perch were introduced in stocking programs for recreational fishing. Dominant alien species, especially in Lowland Zone sites, included Redfin perch, Carp and Eastern gambusia. Other alien fish caught were Goldfish, Brown trout and a single Tench. Species not caught, although predicted to occur under Reference Condition, included River blackfish and three smaller, less well-known species Very few Abnormalities (0.5%) were recorded. Two Intolerant species were caught. Mega- carnivores were caught at three Lowland Zone sites, but none were recorded in the Slopes Zone. 327
Table WIM.2: Wimmera Valley: index, indicators, metrics and derived variables. Values for index and indicators are medians (lower – upper 95% confidence limits)
Valley Zone Lowland Slopes
Fish Index 47 (36–57) 23 (15–42) 84 (61–98) Expectedness Indicator 51 (41–61) 37 (31–45) 78 (63–92) Nativeness Indicator 36 (22–52) 17 (6–37) 67 (33–92) Metric Total species 13 8 10 Native species 5 2 5 Predicted RC–F species count 6 6 6 Alien species 8 6 5 Caught/Predicted native species (%) 83 33 83 Numbers of fish Mean fish per site 59 66 54 Native individuals (%) 64 46 83 Fish biomass Biomass/site all species (g) 6,844 13,650 795 Mean native biomass/fish (g) 20 36 10 Mean alien biomass/fish (g) 283 356 38 Biomass native (%) 11 8 55
328
Table WIM.3: Wimmera Valley: numbers of native fish by Zone. Predicted species (RC–F list) shown by numbers; species not predicted shown by blanks
Zone Native species Lowland Slopes Total
Australian smelt 14 3 17 Carp gudgeons 0 0 0 Common galaxias* 23 57 80 Flat-headed gudgeon 231 66 297 Golden perch* 6 6 Obscure galaxias 0 56 56 River blackfish 0 8 8 Southern pygmy perch 0 265 265
Alien species
Brown trout 4 4 Carp 81 81 Eastern gambusia 46 17 63 Goldfish 41 41 Redfin perch 85 5 90 Tench 1 1
* Introduced to the Wimmera Valley and regarded as an alien species
329
5.24.3 Macroinvertebrates
100 Good 80 Moderate 60 Poor 44 40 36 29 Very Poor 20 Extremely Poor 0 Valley lowland slopes
Figure WIM.3: Wimmera Valley: sampling sites and Zones coloured by SR Macroinvertebrate Index scores (see key). In the graph, horizontal bars are median values; vertical bars are 95% confidence limits associated with the median 330
The Wimmera Valley macroinvertebrate community was in Very Poor Condition. The Lowland and Slopes Zones communities were in Poor and Very Poor Condition, respectively. Both had few ‘expected’ families and disturbance–sensitive families.
Thirty four sites were surveyed across two Zones of the Wimmera Valley in March 2005, yielding 10,093 macroinvertebrates in 75 families (52% of Basin families). Analyses indicate a Very Large Difference from Reference Condition:
• SR Macroinvertebrate Index (SR–MI) = 36 (CL 29–44). • Low proportion of expected families (Filters OE = 25). • Much reduced SIGNAL OE score relative to Reference Condition (Filters SIGNAL OE = 76). SR–MI for the Wimmera Valley is the second lowest value for all Valleys, higher only than that for the Avoca Valley and slightly lower than the Castlereagh and Campaspe Valleys. The Lowland and the Slopes Zone communities showed Large (–) and Very Large Differences from Reference Condition, respectively (SR–MI = 44, 29). In the Slopes Zone, the wide confidence interval for SR–MI (19 points) indicated significant variation in condition among sites. Figure WIM.3 shows sampling sites, Zones and SR–MI values, and Table WIM.4 shows metrics and derived variables. Seventy six percent of expected families were recorded in the Valley. Family richness was substantially less than Reference Condition at all sites. Diversity was moderate (average 22 families per site), with substantial variation among Lowland Zone sites. Most (76, 88%) of the Valley fauna occurred in both Zones. Table WIM.5 shows that Expected (Filters OE) scores indicated substantial losses of expected families, with moderate variation among sites. No sites had a high Filters OE score; nine sites (26%) had a low score. Filters SIGNAL OE scores were at Reference Condition for two sites in the Slopes Zone, 19 sites (56%) had a low score, and the Slopes Zone had 77% of sites with a low score. Most communities were impoverished, lacking disturbance-sensitive families. Table WIM.6 shows ‘common’ and ‘rare’ families. The 13 common families included diving beetles (Dytiscidae), snails (Planorbidae), pond damselflies (Coenagrionidae), amphipods (Ceinidae) and midges (Chironominae). The 20 ‘rare’ families included many associated with flowing water, including aquatic insects. 331
Table WIM.4: Wimmera Valley: macroinvertebrate metrics and derived variables. Index and metric values are medians (lower – upper 95% confidence limits)
Zone Valley Lowland Slopes
Index SR–MI 36 44 29 (29–44) (33–50) (19–38) Metrics Filters OE 25 27 23 (22–28) (23–29) (18–26) FILTERS SIGNAL OE 76 82 73 (72–83) (73–88) (64–78) Families Families per site 22 21 23 minimum – maximum 3–35 3–32 15–35 Total families 75 59 64
Table WIM.5: Wimmera Valley: macroinvertebrate metrics by sites. See Section 3.4.4 for explanation of High, Medium and Low bands
Zone Valley Lowland Slopes
Number of sites 34 21 13
Filters OE High Medium 25 17 8 Low 9 4 5 Filters SIGNAL OE High 2 2 Medium 13 12 1 Low 19 9 10
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Table WIM.6: Wimmera Valley: common and rare macroinvertebrate families by Zones. ‘Common’ families are in the 90th percentile of occurrences in all Valleys across the Basin. ‘Rare’ families are in the 10th percentile. Families not recorded in this Valley, but found elsewhere in the Basin, are not shown
Sites sampled 21 13 34 Number of families sampled 57 66 75 Percent of families in Basin 52.3 54.1 52.4 Percent of families in Valley 76 88 100
Percent of sites by Zone Lowland Slopes VALLEY
Common Chironominae 100 100 100 Dytiscidae 95 100 97 Ceinidae 81 62 74 Coenagrionidae 81 62 74 Planorbidae 43 62 50 Glossiphoniidae 29 31 29 Sialidae 19 23 21 Isostictidae 29 18 Naucoridae 19 15 18 Pyralidae 14 15 15 Megapodagrionidae 23 9 Polycentropodidae 23 9 Haliplidae 5 8 6 Rare Gripopterygidae 15 6 Hydrometridae 5 8 6 Simuliidae 15 6 Aphroteniinae 8 3 Austroperlidae 8 3 Conoesucidae 8 3 Corbiculidae 5 3 Corydalidae 8 3 Dixidae 8 3 Ephydridae 5 3 Hirudinea 8 3 Hydrobiosidae 8 3 Janiridae 5 3 Lepidoptera 5 3 Lymnaeidae 8 3 Oniscigastridae 8 3 Perthiidae 8 3 Philorheithridae 8 3 Richardsonianidae 8 3 Tabanidae 5 3
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5.24.4 Ecosystem Health
The Wimmera Valley river ecosystem was in Very Poor Health (Lowland Zone: Very Poor; Slopes Zone: Poor). Fish abundance was dominated by native species but biomass was dominated by aliens; several expected fish species were absent. Many expected and disturbance-sensitive macroinvertebrate families were absent. The flow regime was highly modified, with reduced high-flows, annual volumes and variability, mainly in the lower reaches.
Summary Theme assessments are as follows (see Table WIM.7): Hydrology Theme • Condition Index SR–HI = 39–100 at selected mainstem locations, indicating Poor Condition (Lowland Zone: Poor to Very Poor; Slopes Zone: Good). • High flows reduced by up to 60% in the lower Wimmera River. Most Slopes Zone sites were in Near Reference Condition. • Incidence and duration of low and zero flows were Near Reference Condition upstream, but extremely reduced downstream. • Flow variability reduced in lower reaches of Wimmera, unchanged elsewhere. • Seasonality of flows showed Moderate to Large Differences from Reference Condition, showing the effect of diversions on the seasonality of minimum flows. • Mean and median annual flow volumes in the lower Wimmera were reduced from Reference Condition by 45–60% and up to 85–95%, respectively. Reductions of 10–85% and up to 60% observed for mean and median annual flow volumes, respectively, in most Slopes Zone sites. Fish Theme • Condition Index SR–FI = 47 (CL 36–57), indicating Poor Condition, in the upper range of Valley scores. Condition varied markedly between Zones (Lowland Zone: Very Poor; Slopes Zone: Good). • Thirteen species caught, including eight alien species. • Predicted native species reduced in the Lowland (67%) and Slopes Zones (17%). • Mean abundance 59 fish per site, mainly native species (36%). • Biomass mainly alien species (89%). Macroinvertebrate Theme • Condition Index SR–MI = 36 (CL 29–44), indicating Very Poor Condition (Lowland Zone: Poor; Slopes Zone: Very Poor). • Moderate diversity and low to very low proportions of expected families, especially in the Slopes Zone. • Low to very low representation of disturbance-sensitive families, especially in the Slopes Zone. 334
Table WIM.7: Wimmera Valley: Condition and Ecosystem Health Assessment. Index values are medians (lower–upper 95% confidence limits). For Hydrology there are no aggregated Index values, and the ratings are not strictly representative of Zones
Zone
Valley Lowland Slopes
Hydrology Condition Poor Very Poor Poor Rating Fish Index 47 (36–57) 28 (15–42) 83 (61–98) Rating Poor Very Poor Good
Macroinvertebrate Index 36 (29–44) 44 (33–50) 29 (19–38) Rating Very Poor Poor Very Poor
Ecosystem Health Very Very Poor Rating Poor Poor
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6. Comparison of Valleys
6.1 Introduction In the preceding Section, assessments of Condition were made using data from the Hydrology, Fish and Macroinvertebrate Themes for each of the 23 Valleys in the Murray-Darling Basin. These were integrated to provide assessments of Ecosystem Health for each Valley. The present Section draws upon the assessments to make comparisons among Valleys, in terms of Condition (by Theme) and Ecosystem Health. In this first SRA report, assessments of Ecosystem Health are based only on the three Themes that are currently active. A more comprehensive, integrated assessment will be possible if more Themes (e.g. Vegetation, Physical Form) are introduced, as proposed.
6.2 Hydrology Theme It would be inappropriate to use the available hydrological data to make quantitative comparisons of Condition among Valleys, as for the Fish and Macroinvertebrate Themes (Sections 6.3–4). Statistical analyses were precluded by the non-random distribution of sample sites, and by inter- jurisdictional differences in the selection of sites and the models used to generate flow data (Section 3.2). These shortcomings also prevent the aggregation of data to make comparisons at the Zone- and Valley-scale. Of 469 sites examined across the Basin, 179 (38%) had a Hydrology Index (SR–HI) of 100, and for another 128 sites, values were greater than 79. Thus, 307 sites (65%) were Near Reference Condition. An additional 107 sites (23%) showed a Moderate Difference from Reference Condition (SR–HI = 60–79), 40 sites (8.5%) showed a Large Difference (SR–HI = 40–59), 12 sites (2.6%) showed a Very Large Difference (SR–HI = 20–39) and only three sites (0.6%) showed an Extreme Difference (SR–HI = 0–29). Although about two-thirds of sites apparently were in Good Condition, this is offset by the fact that the sites which fell short of Reference Condition were mainly in the main channels of the Basin’s principal rivers. Many factors can have a negative impact on hydrological condition in a stream, including: • Regulation: storage for later release in response to downstream demand. Regulation changes the temporal pattern of flow, affecting the seasonality of flow downstream and/or the frequency distribution of flow classes. • Diversion: abstraction of water for consumptive use or transfer to another valley. • Inter-valley transfer: the artificial introduction of water from another catchment. Movement of water between valleys happens naturally in several parts of the Murray-Darling Basin, and transfers are engineered in several Valleys (e.g. diversions to the Murrumbidgee and Upper Murray Valleys via the Snowy Mountains Scheme, and transfers between the Goulburn, Campaspe and Loddon Valleys). • Interception of runoff: in some catchments single irrigation enterprises are based on farm dams capturing runoff that might otherwise have fed streams. This impact so far has been accounted for only in the flow models used to generate data for Victorian streams. The five SRA indicators used to characterise hydrological condition reflect these impacts. For the 469 sites examined, they are distributed as follows:
• High-Flow Events: In 34% of sites, values of this indicator were 100. Including these, 68% of sites were Near Reference Condition, 10% showed a Moderate Difference from 336
Reference Condition, 9% a Large Difference, 9% a Very Large Difference and 3% an Extreme Difference. • Low- and Zero-Flow Events In 38% of sites, values were 100. Including these, 63% of sites were Near Reference Condition, 21% showed a Moderate Difference from Reference Condition, 9% a Large Difference, 4% a Very Large Difference and 4% an Extreme Difference. • Variability: In 19% of sites, values were 100. Including these, 79% of sites were Near Reference Condition, 16% showed a Moderate Difference from Reference Condition, 3% a Large Difference, 1% a Very Large Difference and 1% an Extreme Difference. • Seasonality: In 24% of sites, values were 100. Including these, 64% of sites were Near Reference Condition, 21% showed a Moderate Difference from Reference Condition, 12% a Large Difference, 2% a Very Large Difference and 1% showed an Extreme Difference. • Gross Volume: In 29% of sites, values were 100. Including these, 62% of sites were Near Reference Condition, 14% showed a Moderate Difference from Reference Condition, 13% a Large Difference, 8.0% a Very Large Difference and 2.8% an Extreme Difference. No indicators showed frequent extreme shortfalls from Reference Condition. Most sites were Near Reference Condition, for all indicators. This indicates that hydrological condition is ‘Good’ across most of the Basin. This is significant to the extent that hydrological factors determine habitat characteristics for fish, macroinvertebrates and other aquatic biota. A disproportionate number of sites in Poor Condition, however, were in the Lowland Zones of the major rivers. The hydrological assessments quantify differences from Reference Condition by comparing modelled ‘current’ hydrology with the modelled ‘natural’ flow regime. The assessments therefore account for the effects of climatic conditions, including wet and dry periods. Even for sites rated as Near Reference Condition, the ecosystem still may have been under stress from drought. Of 469 sites assessed in the Basin, 162 showed some shortfall from Reference Condition, although the symptoms varied among sites. The indicator, or indicators, with the lowest score for each of these sites may offer some insight. High-flow Events (HFE) was the lowest indicator for 59 sites, Low- and Zero-flow Events (LZFE) for 47 sites, Variability (V) for only one site, Seasonality (S) for 24 sites and Gross Volume of annual flow (GV) for 32 sites. Of the 59 sites showing most change in HFE, 31 were on the Murray. Other Valleys with sites in this category included the Border Rivers (3 sites), Condamine (3), Darling (4), Goulburn (2), Gwydir (4), Lachlan and Loddon (one each), Macquarie (4), Murrumbidgee (2) and Namoi Valleys (1). In all cases, there were significant diversions upstream or in the vicinity of the site. It appears that HFE is the most modified indicator in rivers where regulation creates high flows which are then diverted at sites downstream (e.g. Murray), or subject to opportunistic harvesting (e.g. Darling and others in the northern Basin). LZFE was the next-ranked indicator (47 sites). Minimal values occurred in the Avoca (1 site), Broken (2), Campaspe (7), Condamine (2), Goulburn (4), Lachlan (3), Loddon (12), Macquarie (4), Central Murray (3), Murrumbidgee (1) and Wimmera Valleys (6). In these rivers, diversions usually are not limited to high flows; they are subject to substantial diversions and, for rivers in the southern Basin, maximum demand (summer-autumn) coincides with the natural period of low flow. Small streams are particularly susceptible. The 24 sites where Seasonality (S) was the most affected indicator were in the southern Basin. Most were influenced by storages, changing the natural winter/summer pattern of high/low flows. GV responds to cumulative diversions or, in some cases, to additions via inter-valley transfers. The 32 sites where GV was the most affected Indicator occurred in the Broken (1 site), Campaspe 337
(2), Condamine (5), Darling (3), Goulburn (1), Gwydir (9), Lachlan (1), Macquarie (1), Lower Murray (1), Central Murray (2), Murrumbidgee (3), Namoi (1) and Wimmera Valleys (2). Most of these sites provide substantial diversions relative to their natural discharge.
6.3 Fish Theme
6.3.1 Species recorded All 23 Valleys (487 sites) were sampled once for fish during 2005–07, yielding 38 species (28 native, 10 alien). Samples included more than 60,600 fish (34,800 native; 25,800 alien) weighing over 4 tonnes (1.3 tonnes native, 2.7 tonnes alien). This is a substantial basis for assessment of fish communities in the Basin. Failure to record a species in a Valley may not mean that it was absent, but it is a reasonable indication that, if present, it was not common. Species could have been missed because of their rarity, or because they favour particular habitats and are less easily caught under the SRA Fish Sampling Protocol. To illustrate, the NSW Rivers Survey 10 years ago found no Murray cod at 20 sites in the Murray catchment (Harris and Gehrke 1997), indicating that cod were not common and populations were fragmented. The survey was criticized by some fishermen who had no difficulty finding cod, because they would target areas where there were known populations, but they overlooked the point that the survey sites were selected at random to enable unbiased statistical analyses. Sampling sites in the SRA also are chosen at random for the same reason. SRA samples are taken from river channels rather than wetlands or other ‘off-channel’ sites (Section 3.3.2). A few species, including Flat-headed galaxias (Galaxias rostratus) and Southern pygmy perch (Nannoperca australis), are more likely to occur in wetlands than in channels, and the survey data therefore are likely to underestimate their true distribution and abundance. Flat- headed galaxias, in particular, were not sampled. Table 6.3-1 shows the ranked abundances of the 38 sampled species, and also shows the numbers of Valleys where species were found. The summary shows that alien species are a major part of the Basin fish fauna, as is well known. Carp, Goldfish and Eastern gambusia were ubiquitous (present in all 23 Valleys), and Eastern gambusia was the most abundant species encountered. Carp, Goldfish and Redfin perch also were abundant and widespread, especially in warm, lowland areas, and Brown trout and Rainbow trout were common in cooler upland streams. These six alien species were rivalled in abundance by a group of native fish, most of them small species (Carp gudgeons, Mountain galaxias, Australian smelt, Un-specked hardyhead and Southern pygmy perch). The exception was Bony herring, a larger native species that flourishes in warm impoundments and slow-flowing lowland waters (e.g. Puckridge and Walker 1990). Golden perch (in 21 of 23 Valleys) were common and widespread throughout the Basin. Murray cod (16 of 23), Freshwater catfish (7 of 23), Trout Cod (3 of 23) and Silver perch (5 of 23) are other native species that, for various reasons (e.g. MDBC 2003b; Gilligan 2005; Lintermans 2007), are less common and less widespread than formerly thought. The lower part of Table 6.3-1 includes species that are uncommon and occupy restricted ranges, and were rarely encountered in sampling. The presence of the alien Crucian carp (in the Campaspe Upland Zone) is noteworthy, having long been suspected but only recently confirmed by genetic data (T.A. Raadik, Dept Sustainability and Environment, Victoria, pers. comm.).
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Table 6.3-1. Relative abundance of fish species by Valleys. The list is ranked by total catch, uncorrected for variations in the number of sites sampled per Valley. The numbers of Valleys where species were recorded are also shown. Alien species are shaded. The accompanying graphic shows catches per Valley on a logarithmic scale
Rank Species Common name Catch Valleys 1 Gambusia holbrooki Eastern gambusia 16,936 23 2 Nematalosa erebi Bony herring 10,661 13 3 Hypseleotris sp. Carp gudgeons 8,301 20 4 Galaxias olidus Mountain galaxias 3,650 14 5 Retropinna semoni Australian smelt 3,317 21 6 Cyprinus carpio Carp 3,030 23 7 Perca fluviatilis Redfin perch 2,287 17 8 Craterocephalus stercusmuscarum Un-specked hardyhead 1,641 12 9 Nannoperca australis Southern pygmy perch 1,403 9 10 Salmo trutta Brown trout 1,301 15 11 Carassius auratus Goldfish 1,107 23 12 Oncorhynchus mykiss Rainbow trout 961 13 13 Gadopsis bispinosus Two-spined blackfish 924 7 14 Melanotaenia fluviatilis Murray-Darling rainbowfish 917 14 15 Galaxias sp. 1 Obscure galaxias 869 10 16 Philypnodon grandiceps Flat-headed gudgeon 774 12 17 Macquaria ambigua ambigua Golden perch 646 21 18 Gadopsis marmoratus River blackfish 608 13 19 Maccullochella peelii peelii Murray cod 380 16 20 Leiopotherapon unicolor Spangled perch 257 9 21 Galaxias maculatus Common galaxias 102 2 22 Tinca tinca Tench 87 3 23 Galaxias fuscus Barred galaxias 79 1 24 Galaxias sp. 2 Riffle galaxias 76 5 25 Tandanus tandanus Freshwater catfish 68 7 26 Misgurnus anguillicaudatus Oriental weatherloach 54 3 27 Craterocephalus amniculus Darling River hardyhead 39 2 28 Rutilus rutilus Roach 30 2 29 Maccullochella macquariensis Trout cod 30 3 30 Bidyanus bidyanus Silver perch 24 5 31 Galaxias brevipinnis Climbing galaxias 15 3 32 Neosilurus hyrtlii Hyrtl’s tandan 11 1 33 Philypnodon macrostomus Dwarf flat-headed gudgeon 5 2 34 Macquaria australasica Macquarie perch 5 2 35 Ambassis agassizii Olive perchlet 4 2 36 Carassius carassius Crucian carp 2 1 Sthn purple-spotted 37 Mogurnda adspersa 2 1 gudgeon 38 Craterocephalus fluviatlilis Murray hardyhead 1 1
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Rank urray, urrum- Avoca Avoca Rivers Border Broken Campaspe Castlereagh Condamine Darling Goulburn Gwydir Kiewa Lachlan Loddon Macquarie Mitta Murray, Upper M Central Murray, Lower M bidgee Namoi Ovens Paroo Warrego Wimmera
1 O O O O O O O • O O O • O • O O O O O O • • O 2 O O O O O O O O O • O OO 3 O O • O O O O O O O O O • OO O O O • O 4 • O O O O O O O O O OO O • 5 O O O O O O O O OO O O • • O O O O O O O 6 O O O O O O O O O O O O O O O O O O O O O O O 7 O O O O O O O O O O O O O O O O O 8 O O • O O • • O O • • • 9 • O • • • O O • O 10 O O O • O • O O O O • O O O • 11 • O O • O O O • O O O O O • • O O O O O O O O 12 • O O • O • O O O • O O O 13 • O O O O O O 14 O O O • • O O O OO • O O O 15 O O O O O O O O • O 16 O O • • • O O O O • O O 17 • O • • • O O • O • O O • O O • O • O O • 18 O O • • O • O O O O O O • 19 O O • • O O O O O • O O O O O • 20 O • O O • O O O O 21 O O 22 O • • 23 O 24 O • O O O 25 O • • O • • • 26 • O O 27 • O 28 • O 29 • O O 30 • • • O • 31 • • O 32 O 33 • • 34 • • 35 • • 36 • 37 • 38 •
KEY blank 0 • 1-10 O 10-100 O 100-1,000 O 1,000-10,000
Figure 6.3-1. Catches per Valley on a logarithmic scale 340
Table 6.3-2. Records of predicted fish species by Valley Zones. Numbers of Zones where species were predicted to occur, compared to the numbers of Zones in which they were caught. Common names follow Lintermans (2007)
Zones Zones Percent Common name Predicted Caught
Australian smelt 59 41 69 Barred galaxias 1 1 100 Black bream 1 Blue spot goby 1 Bony herring 37 27 73 Carp gudgeons 55 47 85 Climbing galaxias 1* 4* 0* Common galaxias 5 4 80 Congolli 9 Darling River hardyhead 9 2 22 Desert rainbowfish 3 Dwarf flat-headed gudgeon 19 4 21 Estuary perch 2 Flat-headed gudgeon 38 21 55 Freshwater catfish 45 14 31 Riffle galaxias 17 8 47 Golden perch 55 41 75 Hyrtl's tandan 7 1 14 Lagoon goby 1 Macquarie perch 34 2 6 Mountain galaxias 37 23 62 Murray cod 58** 32** 52** Murray hardyhead 14 1 7 Flat-headed galaxias 26*** 0*** Murray-Darling rainbowfish 42 25 60 Obscure galaxias 23 14 61 Olive perchlet 29 2 7 Pouched lamprey 4 Rendahl’s tandan 3 River blackfish 46 20 43 Sandy sprat 1 Short-finned eel 5 Short-headed lamprey 15 Silver perch 45 7 16 Small-mouthed hardyhead 1 Southern purple-spotted gudgeon 44 2 5 Southern pygmy perch 35 12 34 Spangled perch 23 15 65 Trout cod 34 4 12 Two-spined blackfish 19 17 89 Un-specked hardyhead 39 18 46 Yarra pygmy perch 1 Yellow-eyed mullet 1
* Climbing galaxias is not native to the four Zones where caught ** Murray cod is not native to two of the 32 Zones where caught *** Flat-headed galaxias lives in wetland habitats, which were not sampled 341
Table 6.3-2 shows how extensive the decline of the Basin’s fish fauna has been. Many native fish species were not caught in Zones where they were predicted to have occurred under Reference Condition. Of 950 combinations of predicted species by Valley-Zone, the predicted species was caught in only 43% of cases. Twelve of 16 species not caught in any Zones where they were predicted are estuary-dependent, and estuarine barrages obstruct their access to the Lower Murray Valley. Non-estuarine species that were not caught in any of the Zones where they were predicted were the Carp gudgeons, Desert rainbowfish, Rendahl’s tandan and Yarra pygmy perch.
6.3.2 Numbers and biomass Figure 6.3-2 shows that numbers of alien and native fish per site varied widely among Valleys. The Campaspe, Goulburn, Upper Murray and Mitta Mitta Valleys had <17 native fish individuals per site, and the Macquarie, Goulburn and Loddon had <35 native fish per site. A peak of 197 native fish per site was recorded in the Lower Murray Valley. Alien fish rivalled or outnumbered native fish in nine of the 23 Valleys, and their dominance was especially striking in the Macquarie, Campaspe, Gwydir and Murrumbidgee Valleys. On the other hand, native fish were numerically dominant (90% or more of individuals) in the Lower and Central Murray, Paroo and Warrego Valleys. The Macquarie, Campaspe, Gwydir and Murrumbidgee Valleys are affected by cold-water pollution from dams, unlike those Valleys with 90% or more natives (apart from the Upper Zone of the Central Murray Valley). Figure 6.3-3 shows somewhat different trends for biomass. High proportions of native biomass were recorded for the Paroo (78%), Darling (62%) and Border Rivers Valleys (60%), and low proportions (<10%) were recorded for the Wimmera, Campaspe, Mitta Mitta and Avoca and, particularly, the Upper Murray Valley (3%). Table 6.3-3 shows the same information in numeric form. Only in the Border Rivers, Darling and Warrego Valleys, and especially the Paroo Valley (78%), did the biomass of native fish exceed that of alien fish. Elsewhere, Carp were overwhelmingly dominant, being 87% of the alien fish biomass (2.36 of 2.7 tonnes) and 58% of the total fish biomass (2.36 of 4.07 tonnes). In comparison, the combined biomass of Brown trout and Rainbow trout was a mere 140 kg. The most productive Valley, in terms of the combined biomass of alien and native fish, was the Darling, with 16.8 kg/site. The Darling was most productive also in terms of native fish only, with 10 kg/site. In each case, the Central Murray Valley was a close second. At the other extreme, the Paroo Valley yielded only 0.75 kg/site of combined alien and native fish biomass although, as noted above, 78% of this was native species. 342
Murray, Lower Condamine Murray, Central Darling Castlereagh Border Rivers Lachlan Macquarie Broken Warrego Paroo Namoi Gwydir Kiewa Ovens Wimmera Native
Avoca Alien Loddon Mitta Mitta Murrumbidgee Murray, Upper Goulburn Campaspe
0 100 200 300 400
Fish per site
Figure 6.3-2. Average fish numbers per site in Valleys, ranked by numbers of native fish
Darling Murray, Central Border Rivers Murray, Lower Macquarie Gwydir Loddon Goulburn Broken Ovens Warrego Condamine Namoi Kiewa Lachlan Campaspe Castlereagh Murrumbidgee Paroo Avoca Native Wimmera Alien Mitta Mitta Murray, Upper
024681012141618
Fish biomass (kg/site)
Figure 6.3-3. Average total fish biomass (kg) per site in Valleys, ranked by biomass of native fish
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Table 6.3-3. Average proportions of native and alien fish numbers and biomass (kg) per site. Percentages are rounded
Composition
Valley Percent Native Percent Alien Numbers Biomass Numbers Biomass
Avoca 68 8 32 92 Border Rivers 63 60 37 40 Broken 74 36 26 64 Campaspe 21 7 79 93 Castlereagh 37 19 63 81 Condamine 86 44 14 56 Darling 89 62 11 38 Goulburn 42 37 58 63 Gwydir 26 33 74 67 Kiewa 43 10 57 90 Lachlan 68 21 32 79 Loddon 58 24 42 76 Macquarie 21 38 79 62 Mitta Mitta 50 8 50 92 Murray, Upper 36 3 64 97 Murray, Central 90 39 10 61 Murray, Lower 93 48 7 52 Murrumbidgee 29 13 71 87 Namoi 63 28 37 72 Ovens 53 23 47 77 Paroo 97 78 3 22 Warrego 95 52 5 48 Wimmera 64 5 36 95
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6.3.3 Observed and predicted communities Table 6.3-4 highlights the prevalence of alien species throughout the Basin, and compares the numbers of observed and predicted species in each Valley. The disparities are an indication of the condition of the native community in each Valley. ‘Predicted’ species are specified by the Reference Condition for Fish (RC-F) in each Zone, a benchmark designed to account for natural differences among Valleys and to facilitate comparisons between communities (Section 3.3.3). RC-F includes a list of species expected to occur in each Valley (by aggregation of lists compiled for Zones) and an estimate of their abundance (‘Rarity’).
Table 6.3-4. Numbers of fish species predicted and observed in Valleys. ‘Predicted’ (RC-F) species are those listed in the Reference Condition list for each Valley. ‘Observed’ species are those recorded in samples; ‘Introduced’ species are native to Australian rivers beyond the Murray-Darling Basin; ‘Translocated’ species are native to other or Zones Valleys in the Basin, but are not in RC-F; ‘Alien’ species are not native to Australia. In the Gwydir and Namoi Valleys, Murray cod were caught in Montane Zones, where they are translocated, and in other Zones, where they are native
Native species Valley Introduced or Alien Predicted Observed Translocated species
Avoca 16 6 0 4 Border Rivers 16 13 0 5 Broken 23 11 0 6 Campaspe 22 8 0 8 Castlereagh 14 6 0 3 Condamine 18 10 0 3 Darling 18 9 0 3 Goulburn 25 14 1 8 Gwydir 15 11 0 6 Kiewa 17 11 1 7 Lachlan 20 10 0 6 Loddon 22 10 0 6 Macquarie 19 10 0 6 Mitta Mitta 14 6 0 6 Murray, Upper 15 7 1 4 Murray, Central 25 10 0 6 Murray, Lower 35 14 0 6 Murrumbidgee 22 13 0 7 Namoi 15 12 0 5 Ovens 22 13 0 6 Paroo 12 7 0 3 Warrego 14 7 0 3 Wimmera 6 5 2 6
345
In the following analysis, the observed differences among Valley fish communities were found not to be related to the year (2005–07) in which the Valley was sampled (ANOSIM analysis of un-transformed counts of individuals: P = 0.56 NS; PRIMER v. 5, Plymouth Marine Laboratory, UK). This validates a comparison between Valleys without having to consider the influence of individual sampling years. One way to examine the data is to construct an ordination ‘map’, showing the difference between the observed native fish community in each Valley and that expected under Reference Condition. The basis for this analysis, the ‘Bray-Curtis distance metric’, takes account of the relative abundances of species, not merely their presence or absence. Bray-Curtis distances are computed between all possible combinations of communities, then subjected to Multi-Dimensional Scaling (e.g. McCune and Grace 2002). This provides a simple plot showing the communities as points in space, separated by distances that show their similarity to one another. The axes in the plot represent combinations of variables, best seen in an ‘overlay’ plot (see below). Figures 6.3-4a-b show an ordination ‘map’ of communities in the 23 Valleys. In Figure 6.3-4a, each Valley is represented by two points, the Reference Condition community (open triangle) and the observed community (solid triangle), joined by a line. The length of the line shows the degree of difference, and its direction reflects the nature of the difference. Reference Condition (RC-F) communities are in the lower half of the plot, and most observed communities are in the upper half. The RC-F communities as a group are more like one another than the observed communities due, in part, to the differential contributions of alien species. The Wimmera RC-F community lacks a number of otherwise common species (e.g. Carp gudgeons, Golden perch, Murray cod, Freshwater catfish, Silver perch, Bony herring) because the Valley is isolated from the main Murray-Darling drainage system, and its position on the plot is displaced accordingly. Figure 6.3-4b shows the same ordination, but with an overlay of radiating lines showing the species most responsible for the dispersion of the Valleys in the plot. Murray cod and certain other species do not feature here because they do not provide strong discrimination between Valleys. Again, the length of each line indicates the degree of influence of the named species, and its orientation indicates the direction of increase in the abundance of that species. The separation of observed communities and RC-F communities is associated with apparent declines in the distribution and abundance of Macquarie perch, Olive perchlet, Silver perch and Flat-headed galaxias. As mentioned (Section 6.3-1), the latter is mainly a wetland species and was absent from samples. It is listed as ‘rare’ or ‘occasional’ in the RC–F communities of 14 Valleys (26 Zones). 346
(a)
(b) Figure 6.3-4. Ordination of fish communities Reference Condition communities as open triangles; observed communities as solid triangles. Plots generated by Multi-Dimensional Scaling on a normalized Bray-Curtis distance matrix (PC-ORD v. 5.12: MjM Software, Oregon). Stress for 2-D solution: 14.5%. (a) Observed and Reference Condition communities for each Valley, with lines linking the members of each pair. (b) An overlay showing the species responsible for most of the variation in ordination scores. The lengths and orientations of the radiating lines show the influence of the named species (coefficients of determination, r2 >0.2). 347
The observed communities are displaced upward, relative to RC-F communities, by Carp, Goldfish and Eastern gambusia, and Carp gudgeons. Some are displaced to the left due to the greater abundance of River blackfish and the alien Brown trout and Rainbow trout, and others are displaced to the right due to Bony herring, Golden perch and Spangled perch. It is tempting to look further for sub-groups, but this could be misleading (for example, it could suggest that Carp, Goldfish and Eastern gambusia are typical of some Valleys, when they occur in all Valleys). In general, Valleys with cool upper reaches (e.g. Broken, Goulburn, Loddon, Mitta Mitta, Upper Murray) favour trout and River blackfish, and Valleys with warm, lowland reaches (e.g. Condamine, Darling, Lower Murray, Central Murray, Paroo, Warrego) favour Bony herring, Golden perch and Spangled perch (the latter species is rare, however, below 33ºS latitude: Lintermans 2007).
6.3.4 Condition indices Figure 6.3-5 shows indices of fish condition (SR–FI) for all Valleys, arranged in descending order. The Valleys form three reasonably distinct groups (A-C), and Group B may be sub-divided into B1 (near Group A) and B2 (near Group C). Group A contains only the Paroo Valley, with an SR–FI score of 78. The proportion of native fish was highest (97%) in this Valley, although only seven of 13 RC-F species were recorded. The average number of fish per site (58.2) was modest, but only three alien species were present and in very low numbers (2 fish per site). Group B1 includes seven Valleys (Border Rivers, Condamine, Darling, Namoi, Central and Lower Murray, Warrego) with moderately high SR–FI scores of 53-61. With the exception of the Lower Murray, native species in these Valleys were a moderate to high proportion of the total catch. The Darling and Condamine Valleys had fewer alien species, partly because they lack cool, upland reaches to sustain trout. All members of Groups A and B1, except for the Lower Murray Valley, are in the northerly, summer-rainfall region of the Basin. Group B2 contains seven Valleys (Avoca, Broken, Gwydir, Kiewa, Macquarie, Ovens, Wimmera), with low SR–FI scores of 26–51. The Wimmera Valley had the highest Observed-to- Predicted (RC-F) species ratio (OP = 0.83) of all Valleys, but its SR–FI score was diminished because only six RC-F species were predicted (less that half that of other Valleys), and it had six alien and two introduced species native to other parts of the Basin (Common galaxias, Golden perch). Indeed, the biomass of alien fish in the Wimmera Valley far exceeded that of native fish. The Kiewa and Ovens Valleys had moderate OP ratios (0.65, 0.59, respectively), but the alien biomass in both far exceeded that of native species, particularly in the Kiewa, where alien species were 90% of the total biomass. In the Macquarie Valley, native species were well represented but outnumbered by aliens. In the Broken and Avoca Valleys, fewer than half of the predicted species were observed, and alien species in the Avoca were 92% of total biomass. Members of Group B2, except for the Warrego and Macquarie Valleys, are in the southerly, winter-spring rainfall region of the Basin. Group C contains eight Valleys with very low SR–FI scores of 5–14 (Campaspe, Castlereagh, Goulburn, Lachlan, Loddon, Mitta Mitta, Murrumbidgee, Upper Murray). The Campaspe, Mitta Mitta and Upper Murray have the highest proportions of alien biomass of any Valleys (92-97%), and the latter two have extensive upland reaches populated by trout and few large native species. Members of Group C, except for the Castlereagh Valley, are in the southerly winter-spring rainfall region of the Basin.
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100 A Good
80 B1 B2 Moderate 60 C Poor 40 Very Poor Fish Index, SR-FI Sustainable Rivers 20 Extremely Poor 0 Paroo Kiewa Avoca Namoi Ovens Gwydir Darling Broken Loddon Lachlan Warrego Wimmera Goulburn Mitta Mitta Mitta Macquarie Campaspe Condamine Castlereagh Border Rivers Murray, Upper Murray, Murray, Lower Murray, Murrumbidgee Murray, Central
Figure 6.3-5. Valleys ranked by SR Fish Index (SR–FI) scores. Short horizontal bars are medians; vertical lines show the associated 95% confidence limits. The range of medians in each of four groups is shown alongside each label (A, B1, B2, C). For explanation of groups, see text. The SRA colour standard is included, with a key to Condition
6.3.5 Zone communities Each Valley in the SRA is divided into Zones that accord with altitudinal (hence biogeographical) differences, except in the Lower and Central Murray and Darling Valleys (Section 2.2.3). In these exceptions, the main-channel Zones are comparable to a ‘Lowland Zone’, and the Mt Lofty Zone in the Lower Murray Valley is comparable to a ‘Slopes’ Zone. In the Basin as a whole, Lowland Zones are best represented and Montane Zones are least represented. For some analyses it is interesting to separate Valleys (and Zones in Valleys) in the northern region, where summer rainfall predominates, and the southern region, where rainfall peaks in winter and spring. The Macquarie Valley approximates the division between the winter-spring rainfall group and the summer-rainfall group. For example, Table 6.3-5 shows that the mean combined biomass of alien and native fish was similar in summer-rainfall Zones (3.72 versus 3.59 kg per site), whereas winter-rainfall Zones consistently had about three-fold more alien fish biomass than native fish biomass (6.30 versus 2.13 kg per site). In winter-rainfall Zones, where trout are common, the native species generally were smaller on average (4.4 g/fish) than in other Zones. The summer-rainfall Valley Zones support abundant small alien fish, especially Eastern gambusia. Table 6.3-6 shows that median values of the Fish Condition Index (SR–FI) in Zones varied from zero (Goulburn Slopes, Kiewa Upland, Murrumbidgee Slopes and Upland Zones) to 80 (Border Rivers Upland Zone). In general, the communities of Zones in the summer-rainfall Valleys appear to be in better condition; this is especially so for the Lowland and Slopes Zones, most of which have higher than average SR–FI scores. Most of the high-altitude Zones in winter-rainfall Valleys have below-average scores, reflecting the local dominance of trout and other alien species.
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Table 6.3-5. Numbers and biomass (g) of fish per site, by Zones. Biomass data >10 g are rounded. ‘Intro/Trans’ = Introduced or Translocated species
Mean Number/Biomass per site Mean Biomass
Rainfall Native Alien Introduced (g/fish) Sites Intro/ Class Number Biomass Number Biomass Number Biomass Native Alien Trans
Summer Rainfall Lowland 83 77.1 3,972 15.0 3,167 0 0 52 211 0 Slopes 44 124.8 3,999 55.8 6,986 0 0 32 125 0 Upland 28 87.4 1,800 194.7 2,229 0 0 21 12 0 Montane 21 62.0 3,606 87.6 1,093 0.6 1,180 58 13 1,905 Winter-Spring Rainfall Lowland 128 86.1 4,429 24.0 9,706 0.2 54 51 405 222 Slopes 105 49.8 1,093 82.1 5,786 0.6 2.1 22 71 3.6 Upland 64 27.0 256 37.7 3,159 0.1 0.3 9.5 84 5.8 Montane 33 33.5 147 23.2 839 0.2 0.6 4.4 36 3.4
Table 6.3-6. Distribution of median Fish Index (SR–FI) values in ‘zones’ sorted by hydrological and altitudinal classes
Quartiles for median values of SR–FI Rainfall Altitude Count First Second Third Fourth Class Class 0 - 0.16 0.18-0.37 0.37-0.55 0.56-0.80
Lowland 10 1 1 3 5 Slopes 6 1 5 Upland 4 1 1 2
Summer Montane 3 1 2 Total 23 3 3 5 12 Lowland 17 1 7 7 2 Slopes 14 6 2 4 2 Upland 9 6 3 Montane 5 1 2 1 1
Winter-Spring Winter-Spring Total 45 14 14 12 5
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6.4 Macroinvertebrate Theme
6.4.1 Families recorded All Valleys (773 sites) were sampled once for macroinvertebrates between October 2004 and June 2006, yielding over 209,100 specimens in 124 families (strictly, a mixture of taxonomic groups, most identified to family level). This is a substantial basis to assess macroinvertebrate communities in the Basin. These assessments are for benthic (bottom-dwelling) macroinvertebrates. They are based on the presence of families and the composition of assemblages, but not on estimates of abundance or biomass (appropriate methods are planned for trial in 2008). Crayfish, freshwater mussels and other large invertebrates are not considered, as suitable protocols have not yet been developed. Samples were taken at randomly selected sites, and exclusively from channels, not wetlands or other ‘off-channel’ sites (Section 3.4.2). Failure to record a macroinvertebrate family in a Valley may not mean that it was absent, but it is a reasonable indication that, if present, it was not common. Families could have been missed because of their rarity, or because they strongly favour particular habitats. Sampling was in stream channels only, in edge and riffle habitats or in edge habitats only where riffles were absent (as in most lowland sites). Ten of the 23 Valleys were sampled in edge habitats only at all sites, 10 Valleys were sampled mainly in edge habitats with riffles at a few sites, and three Valleys were sampled at riffle and edge habitats at most or all sites. More information is shown in Table 6.4-1.
Table 6.4-1. Macroinvertebrate habitats sampled in each Valley. Includes some Valley Zones (italics) where there were marked differences in habitats sampled
Only Most or All Some Edge Riffle and Edge Riffle and Edge
Avoca Broken (Slopes) Campaspe Border Rivers Kiewa Goulburn Broken (Lowland) Mitta Mitta Gwydir Castlereagh Ovens (Slopes to Montane) Lachlan Murray Central Murray, Upper Loddon Condamine Murray Lower (Mt Lofty) Darling Murrumbidgee Murray Lower (Lower to Upper) Macquarie Murrumbidgee Namoi Paroo Ovens (Lowland) Warrego Wimmera
The frequencies of occurrence of each family across the Basin are summarized in Tables 6.4.2a-b. Lists of family names will be daunting for readers not familiar with freshwater invertebrates, but there is no easy alternative as many so-called ‘common names’ are not widely used. There are several good identification guides, including Williams (1980), Hawking and Smith (1997) and Gooderham and Tsyrlin (2002), and many Internet sources including a web-based guide to ident- ification, with notes on ecology
Table 6.4-2a shows 23 families that were ubiquitous (present in all 23 Valleys). Many of these are families commonly found in edge and slow flowing river habitats throughout eastern Australia, are readily able to colonize freshwaters and generally are tolerant to pollution or human disturbance. All but three of these common taxa (Acarina (mites), Baetidae (mayflies), Leptoceridae (caddisflies)) have SIGNAL OE scores (Stream Invertebrate Grade Number Average Level: Chessman 2003) of four or less, out of a possible 10, indicating that they are mainly disturbance-tolerant. Table 6.4-2b lists families that range from rare to common in the Basin. The rarer families occupy restricted ranges (for example, 14 families were each found at only one site). At least half of these had SIGNAL OE scores indicating moderate to high sensitivity to disturbance.
Table 6.4-2a. Incidence of the most common macroinvertebrate families in all Valleys. Families ranked by occurrence at all sites. The numbers of Valleys where families occurred are also shown
Number n Rank Scientific name Common name of sites Valleys
1 Chironominae Midges 737 23 (all) 2 Corixidae Water boatmen (bugs) 699 23 (all) 3 Leptoceridae Longhorn caddisfly 662 23 (all) 4 Tanypodinae Midges 620 23 (all) 5 Dytiscidae Predaceous diving beetles 574 23 (all) 6 Veliidae Riffle bugs; Broad-shouldered water striders 532 23 (all) 7 Notonectidae Backswimmers (bugs) 530 23 (all) 8 Oligochaeta Freshwater worms 525 23 (all) 9 Acarina Aquatic mites 522 23 (all) 10 Baetidae Mayflies 521 23 (all) 11 Orthocladiinae Midges 517 23 (all) 12 Ceratopogonidae Midges 490 23 (all) 13 Hydrophilidae Water scavenger beetles 483 23 (all) 14 Caenidae Mayflies 481 23 (all) 15 Atyidae Freshwater shrimps 415 23 (all) 16 Hydraenidae Small water beetles 404 23 (all) 17 Parastacidae Crayfish 353 23 (all) 18 Coenagrionidae Pond damselfies 333 23 (all) 19 Ancylidae Freshwater limpets 271 23 (all) 20 Culicidae Mosquitoes 219 23 (all) 21 Ecnomidae Ecnomid caddisflies 215 23 (all) 22 Planorbidae Ramshorn or left-handed pond snails 201 23 (all) 23 Hirudinea Aquatic leeches 117 23 (all)
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Table 6.4-2b. Incidence of less common macroinvertebrate families. Families ranked by occurrence at all sites. The numbers of Valleys where families occurred are also shown
n n Rank Families Sites Valleys
Leptophlebiidae, Palaemonidae, Physidae, Simuliidae, Scirtidae, 24–34 200–350 18–21 Tipulidae, Hydroptilidae, Gerridae, Elmidae, Aeshnidae, Corduliidae
Hydrobiosidae, Hydropsychidae, Gripopterygidae, Gyrinidae, 35–46 Gomphidae, Ceinidae, Conoesucidae, Psephenidae, Tabanidae, 100–200 8–22 Libellulidae, Coloburiscidae, Nepidae
Calamoceratidae, Dixidae, Corallanidae, Philorheithridae, Mesoveliidae, Hydrometridae, Oniscigastridae, Staphylinidae, Corydalidae, Lestidae, 47–65 50–99 9–19 Glossosomatidae, Lymnaeidae, Corbiculidae, Philopotamidae, Isostictidae, Naucoridae, Austroperlidae, Sphaeriidae, Pleidae
Helicopsychidae, Synlestidae, Notonemouridae, Pyralidae, Calocidae, Hydrobiidae, Protoneuridae, Temnocephalidea, Paramelitidae, Athericidae, Eusiridae, Eustheniidae, Atriplectididae, Diamesinae, Megapodagrionidae, Janiridae, Ptilodactylidae, Sialidae, Hebridae, 66–100 10–49 3-15 Noteridae, Ephydridae, Psychodidae, Limnephilidae, Tasimiidae, Muscidae, Sciomyzidae, Heteroceridae, Phreatoicidae, Helicophidae, Gelastocoridae, Thiaridae, Haliplidae, Odontoceridae, Podonominae, Nemertea
Gordiidae, Perthiidae, Polycentropodidae, Aphroteniinae, Nevrothidae, 101–114 Diphlebiidae, Neoniphargidae, Ameletopsidae, Thaumaleidae, 2–9 1–6 Osmylidae, Blephariceridae, Viviparidae, Limnichidae, Nesamelitidae
Anostraca, Antipodoeciidae, Hymenosomatidae, Nannochoristidae, 115–124 Paracalliopidae, Paratelphusidae, Phreatoicopsidae, Spongillidae, 1 1 Tanyderidae
6.4.2 Observed and expected communities Table 6.4-3 compares the numbers of observed and expected families in each Valley, where ‘expected’ families are specified by the Reference Condition for Macroinvertebrates (determined using the Filters model: Section 3.4.4). The difference between observed and expected numbers of families is an indication of community condition. Thus, the communities with the highest and lowest Condition (Paroo and Avoca, respectively) also had the highest and lowest proportions of expected families. The range of Reference Condition values reflects genuine differences in family-level diversity between southern versus northern and upland versus lowland systems. 353
Table 6.4-3. Numbers of macroinvertebrate families in Valley samples compared to those expected under Reference Condition (determined using the Filters model)
n Families Ratio, Observed Expected %
Avoca 54 95 57 Border Rivers 63 95 66 Broken 78 104 75 Campaspe 78 100 78 Castlereagh 53 93 57 Condamine 55 79 70 Darling 49 57 86 Goulburn 88 104 85 Gwydir 70 101 69 Kiewa 84 104 81 Lachlan 69 103 67 Loddon 76 102 75 Macquarie 72 103 70 Mitta Mitta 82 103 80 Murray, Upper 58 103 82 Murray, Central 57 97 59 Murray, Lower 86 71 83 Murrumbidgee 76 105 72 Namoi 73 101 72 Ovens 86 104 83 Paroo 42 45 93 Warrego 45 55 82 Wimmera 75 99 76
An ordination is a useful way to display the differences between the communities in each Valley and those expected under Reference Condition. In this analysis, the ‘Bray-Curtis distance metric’ is applied to records of the presence and absence of families in Valleys. Bray-Curtis distances are computed for all combinations of Valleys, and then subjected to Multi-Dimensional Scaling (e.g. McCune and Grace 2002). This produces a plot, like a map, showing the Valley communities as points in space, separated by distances that show their similarity (or dissimilarity) to one another, in terms of composition. Figure 6.4-4 shows such an ordination of macroinvertebrate communities. Each Valley is repre- sented by two points — the Reference Condition community (open triangles) and the observed community (solid triangles) — joined by lines whose length and direction indicate the nature and size of the difference. Reference Condition macroinvertebrate communities are clustered tightly in the lower left-hand area of the plot, except for the Darling, Warrego and Paroo Valleys, with the Paroo being especially distinctive. These three Valleys have the lowest numbers of expected families (45–57, Table 6.4-3). The distribution of observed and Reference Condition communities is influenced by the kinds of habitats sampled in each Valley; it is the difference between observed and Reference Condition communities, however, that reflects condition. The observed communities are more widely dispersed, indicating greater variation in composition in the observed Valley data. The ‘spread’ of Reference Condition communities in Figure 6.4-4 again 354 reflects genuine differences in family-level diversity between southern versus northern and lowland versus upland systems, and shifts in composition (left to right) toward families tolerant of slower flow and higher temperatures. Although it is not shown on the ordination plot, to avoid clutter, most diversity (the numbers of families in samples) occurs in Valleys clustered in the lower left corner of the plot. Most Valleys show reduced diversity, relative to Reference Condition. This is especially striking for the Avoca, Lower Murray, Paroo and Warrego Valleys. The Central Murray and Murrumbidgee Valleys also show trends unlike those of other Valleys. The patterns in the ordination need to be interpreted cautiously, as to some extent they must reflect the inclusion of riffle-habitat samples in the data for some but not all Valleys. The axes in an ordination plot represent complex combinations of variables, often shown as an ‘overlay’ plot (cf. Section 6.3.3). As mentioned, this is not included here because the separations between samples and their respective Reference Condition communities are correlated with a very large number of invertebrate families. Curiously, one family shows a contrary trend to all others, in that its influence increases toward the right of the ordination plot. This family, the Corallanidae, contains a single Murray-Darling Basin species, Tachaea caridophaga, an isopod parasitic on atyid shrimps and palaemonid prawns. Four Valley communities stand apart (Fig. 6.4-4):
• The Avoca Valley community is the most different from Reference Condition (RC-M). Compared to the rest of the Basin, the observed community is distinguished by a low incidence of Caenidae (mayfly nymphs), Elmidae (riffle beetles), Orthocladiinae (midge larvae) and Tipulidae (crane fly larvae), and a high incidence of Ceinidae (amphipods). • The Lower Murray Valley community also is strikingly different from its Reference Condition counterpart. Low incidences were recorded for Corbiculidae (little basket shells) and Hydroptilidae (microcaddis larvae), and high incidences were recorded for Dytiscidae (predaceous water beetles), Hydrophilidae (water scavenger beetles), Notonectidae (back- swimmers) and Veliidae (riffle bugs). • Both the observed and Reference Condition communities in the Paroo Valley are distinctive, reflecting the prevalence of small, lentic (still-water) crustaceans (e.g. Ostracoda). Palaemonid prawns also are widespread. Less well-represented families include Atyidae (shrimps), Baetidae (mayfly nymphs) and Veliidae (riffle bugs).
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Avoca
Murray, Lower Kiewa Broken Campaspe
Mitta Mitta Wimmera Murray, Upper Ovens Lachlan Paroo Castlereagh Goulburn Warrego Loddon Namoi Border Rivers Condamine
Macquarie Darling
Gwydir
Murray, Central Murrumbidgee
Figure 6.4-4. Ordination of macroinvertebrate communities. Reference Condition communities as open triangles; observed communities as solid triangles. Generated by Multi-Dimensional Scaling on a Bray-Curtis distance matrix (PC-ORD v. 5.12: MjM Software, Oregon). Stress for 2-D solution: 12.9%.
The extreme drought in some Valleys before and during sampling will have affected macro- invertebrate communities. Contraction of wetted areas is likely to have reduced habitat quality through changes in water quality, temperature, food resources, competition and predation. An analysis run to determine whether differences between macroinvertebrate communities were related to the years in which samples were taken proved negative (ANOSIM analysis of family presence/absence data, P = 0.68: PRIMER v. 5, Plymouth Marine Laboratory, UK).
6.4.3 Condition indices Figure 6.4-5 shows median Macroinvertebrate Condition Index (SR–MI) for all Valleys, arranged in descending order. These are also shown in Table 6.4.4, alongside data for two metrics, Filters OE and Filters SIGNAL OE. The Valleys form three broad groups (A-C), and Group B may be sub-divided into B1 (near Group A) and B2 (near Group C). Group A contains the Border Rivers, Upper Murray and Paroo Valleys, with SR–MI scores of 64–66. Group B1 includes five Valleys (Condamine, Kiewa, Gwydir, Mitta Mitta and Ovens) with SR– MI scores of 55–59. Four members of Groups A and B1 (Border Rivers, Condamine, Gwydir, Paroo) are in the northerly summer-rainfall region of the Basin, and three (Kiewa, Mitta Mitta, Ovens) are in the winter-spring rainfall region. 356
Group B2 contains 11 Valleys (Broken, Darling, Goulburn, Lachlan, Loddon, Macquarie, Lower Murray, Central Murray, Murrumbidgee, Namoi, Warrego) with SR–MI scores of 46–53. Most members of Group B2, except for the Namoi, Warrego and Darling Valleys, are in the southern winter-spring rainfall region of the Basin. Group C contains four Valleys with low SR–MI scores of 34–41 (Castlereagh, Campaspe, Wimmera, Avoca). All except the Castlereagh are in the central Murray region, in the southern winter-spring rainfall part of the Basin.
100 A Good 80 B1 B2 C Moderate 60
Poor 40
Sustainable Rivers Rivers Sustainable Very Poor 20 Macroinvertebrate Index, SR-MI SR-MI Index, Macroinvertebrate Extremely Poor 0 Paroo Kiewa Avoca Namoi Ovens Gwydir Darling Broken Loddon Lachlan Warrego Wimmera Goulburn Macquarie Mitta Mitta Mitta Campaspe Condamine Castlereagh Border Rivers Border Murrumbidgee Murray, Upper Murray, Lower Murray, Murray, Central Murray,
Figure 6.4-5. Valleys ranked by SR Macroinvertebrate Index (SR–MI) scores. Short horizontal bars are medians; vertical lines show the associated 95% confidence limits. The range of medians in each of four groups is shown alongside each label (A, B1, B2, C). For explanation of groups, see text. The SRA colour standard is included, with a key to Condition
357
Table 6.4-4. SR Macroinvertebrate Index (SR–MI) and associated metrics. Data are medians (lower–upper 95% confidence limits), in descending order of SR–MI
Valley SR-MI Filters OE Filters SIGNAL OE
Border Rivers 66 (58-75) 38 (34-42) 89 (87-92) Murray, Upper 65 (59-69) 31 (29-32) 107 (101-111) Paroo 64 (58-72) 36 (33-39) 94 (91-97) Kiewa 59 (58-70) 29 (28-33) 105 (101-110) Mitta Mitta 59 (51-65) 29 (26-32) 104 (96-110) Ovens 57 (51-59) 29 (26-29) 102 (98-107) Gwydir 56 (51-61) 32 (29-35) 91 (87-95) Condamine 55 (51-64) 31 (28-36) 92 (90-95) Lachlan 53 (49-56) 30 (27-32) 92 (89-95) Darling 52 (48-56) 29 (27-32) 91 (89-95) Namoi 52 (48-57) 30 (28-33) 89 (84-92) Broken 51 (46-53) 28 (26-29) 94 (87-97) Loddon 51 (45-54) 31 (27-33) 85 (80-89) Goulburn 50 (49-59) 26 (25-30) 97 (97-105) Macquarie 50 (46-54) 28 (26-30) 90 (85-94) Warrego 49 (39-53) 27 (22-30) 91 (87-95) Murray, Lower 48 (47-56) 25 (25-29) 97 (90-103) Murrumbidgee 48 (43-52) 26 (24-28) 93 (85-97) Murray, Central 46 (41-50) 25 (23-27) 92 (87-97) Campaspe 41 (36-45) 26 (23-28) 80 (76-83) Castlereagh 41 (36-52) 25 (22-32) 81 (78-87) Wimmera 36 (29-44) 25 (22-28) 76 (72-83) Avoca 34 (29-37) 21 (20-23) 79 (75-80)
358
6.5 Correlation of Theme indices The Valley scores for the Fish and Macroinvertebrate Themes did not correspond closely (r = 0.16) (Figure. 6.5-1). This was anticipated, as the two Themes address different patterns and processes operating at different scales of space and time. If there were a close relationship, it would suggest that one of the Themes was at least partly redundant. A striking feature of the plot is that spread of index values in the Macroinvertebrate Theme is less than that for the Fish Theme. This is mainly due to the fact that most human impacts in the Basin cause a shift in community composition, but rarely cause complete changes in composition or complete loss of families at individual sites. The range of values is influenced also by aggregation to Valley scale and the use of family-level taxonomy. The range is likely to be increased by inclusion of numbers and biomass data, planned for evaluation in 2008. In addition, the SRA Sampling Protocol does not yet take adequate account of some crustaceans and molluscs. These issues may lead to future refinements in sampling and analysis.
100
80
60
40
20 SR MacroinvertebrateCondition (SR-MI)
0 0 20 40 60 80 100 SR Fish Condition (SR-FI)
Figure 6.5-1. Comparison of index scores from the Fish and Macroinvertebrate Themes for all Valleys in the Murray-Darling Basin. The point at far right is the Paroo Valley, which scored high in both Themes
359
6.6 Ecosystem Health All 23 Valleys and constituent Zones were assigned a level of Ecosystem Health based on Valley- and Zone-scale Condition assessments for hydrology, fish and macroinvertebrates (Figure 5.1-1). Table 6.6-1 shows the Valleys ranked according to their health ratings. Only the Paroo Valley was rated in Good Health, and only the Border Rivers and Condamine Valleys were rated in Moderate Health. Most Valleys were rated in Poor (7 Valleys) or Very Poor Health (13 Valleys). None was rated in Extremely Poor Health.
Table 6.6-1. Ecosystem Health assessments by Valley, 2004-07. Valleys are arranged in rank order within Health Ratings
Health Valley Rank Rating
Good Paroo 1 Moderate Border Rivers, Condamine 2 Namoi, Ovens, Warrego 3 Poor Gwydir 4 Darling, Murray Lower, Murray Central 5 Murray Upper, Wimmera 6 Very Avoca, Broken, Macquarie 7 Poor Campaspe, Castlereagh, Kiewa, Lachlan, Loddon, Mitta Mitta 8 Murrumbidgee, Goulburn 9
Table 6.6-2 shows that two Zones were rated in Good Health, namely the Paroo Lowland Zone (which accommodates the entire river) and the Border Rivers Slopes Zone. Two Zones each from the Border Rivers and Condamine Valleys were assessed in Moderate Health (Lowland and Upland, Lowland and Slopes Zones, respectively). Two Zones each from the Namoi and Ovens Valleys were also assessed in Moderate Health (Slopes and Upland, Upland and Montane Zones, respectively). The Slopes Zones from each of the Broken and Warrego Valleys also were rated in Moderate Health. Most Zones were rated as Poor (19 Zones) or Very Poor (27 Zones). Three Zones, the Campaspe Slopes and Upland Zones and the Castlereagh Slopes Zone were rated in Extremely Poor Health. The health of the Loddon Upland Zone could not be assessed, for want of fish and hydrology data (Section 4). Overall, Upland and Montane Zones rated similarly to the Lowland and Slopes Zones. Seventeen of 21 (81%) of the former were rated in Poor or Very Poor Health, compared to 32 of 41 (78%) of the latter. The Upland Zones were however notable in having a higher proportion (9 of 13 or 69%) in Very or Extremely Poor Health than the other Zones (which ranged from 38 to 45%). Northern ‘summer rainfall’ Valleys generally were in better health than southern ‘winter-spring rainfall’ Valleys. Only two (22%) of the nine northern Valleys were rated as Very Poor Health, compared to nine (64%) of the 14 southern Valleys. In addition, all three Valleys rated in Moderate to Good Health were in the northern Basin.
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Table 6.6-2. Ecosystem Health assessments by Zone, 2004-07. The Central and Lower Murray and Darling Valleys are included as single Lowland Zones, except that the Mt Lofty Zone (Lower Murray) is counted as a Slopes Zone
Health Zone Count Rating Lowland Slopes Upland Montane
Good Paroo Border Rivers 2 Border Rivers, Broken, Border Rivers, Ovens Condamine, Condamine, Namoi, 11 Moderate Namoi Namoi, Ovens Warrego
Darling, Avoca, Mitta Mitta Border Rivers, Gwydir, Gwydir, Lachlan, Lachlan, Kiewa, Murray Upper, Macquarie, Murray Lower, Namoi 19 Poor Murray Central, Ovens, Murrumbidgee, Wimmera Ovens, Warrego
Avoca, Goulburn, Castlereagh, Gwydir, Broken, Lachlan, Goulburn, Mitta Mitta, Campaspe, Loddon, Gwydir, Murrumbidgee Castlereagh, Macquarie, Kiewa, Very Goulburn, Mitta Mitta, Lachlan, 27 Poor Kiewa, Murray Upper, Macquarie, Loddon, Murrumbidgee Murray Upper, Murray Lower, Murrumbidgee Wimmera
Extremely Campaspe, Campaspe 3 Poor Castlereagh
Count 21 20 13 8 62
361
7. Progress, Problems and Prospects
7.1 Progress and future development This report describes the results of the first round of sampling and assessment for the SRA Hydrology, Fish and Macroinvertebrate Themes. Assessments have been made of Condition at Zone and Valley scales, and Ecosystem Health at the Valley scale, with accompanying measures of statistical reliability. Future reports will also describe trends over time, beginning with macro- invertebrates in the SRA Implementation and Operations Report for 2008, then fish (and macro- invertebrates again) in the report for 2009. Several improvements are proposed for evaluation and incorporation into future reports. ISRAG recommends that these be considered for SRA Report 2, due in 2010: • Within Themes, there is scope for improvements to some metrics, additions to metrics, and improvements to methods for defining Reference Condition. Key points include: o Refinement of the Macroinvertebrate Theme Filters method for Reference Condition, with regard for the probabilities of occurrence of taxa; o Additions to the Macroinvertebrate Theme of semi-quantitative data, species- level identifications (for selected groups) and data for crustaceans and molluscs; o Addition to the Fish Theme of metrics describing recruitment; and o Inclusion in the Hydrology Theme of data from upper catchments and unregulated drainages and spatial and hydraulic measures of floodplain water regimes, and incorporation of the influence of farm dams and ground- and surface-water interactions in models. • Additional Themes would provide more comprehensive assessments. Two new Themes (Physical Form, Vegetation) have been initiated, and a possible Waterbird Theme also should be explored, perhaps as part of a larger national framework. • Increased sampling frequency for some or all of the biological Themes would help to better define trends and elucidate responses to climatic changes. • Increased sampling intensity in some areas would increase confidence in the Valley and Zone results, and provide more utility for jurisdictions using the data at smaller, local scales. Cost-benefit and the availability of wetted sites are significant constraints. • The existing Themes, and those under development, deal with current ecosystem conditions and changes. There is a need also for capacity to detect impending changes, and this might be achieved by monitoring resilience. Future reports will describe techniques for monitoring resilience in the Fish and Vegetation Themes. • Finalising procedures to evaluate trends across Themes (due to commence in 2008).
7.2 Audit framework The SRA has developed a reasonably simple, transparent framework to report on the Condition of a small number of biophysical components, represented by Themes, that are integrated to describe the ecological health of the Basin’s rivers. Raw and derived data are used to derive simple metrics that are integrated to provide summary indices of Condition, and integrated again to indicate Ecosystem Health. The analyses are flexible, to accommodate future refinements, but more sophisticated analyses may be warranted to aid diagnosis of factors causing changes in health, and to assist explorations of data for individual Valleys or regions and evaluations of large-scale responses to management and climate change. These applications are beyond the scope of the 362 present Audit, but should be considered as possible extensions, perhaps as a project tied to the MDBC Integrated Basin Reporting program. In addition, the current framework addresses only the ecological health of river-channel elements. The planned addition of vegetation, hydrological and geomorphological assessments for floodplains will considerably expand the scope of the Audit. ISRAG considers that it is essential to include assessments of wetland and woodland systems, including the Lower Lakes and Coorong and other icon sites of The Living Murray initiative.
7.3 Other issues
7.3.1 General ISRAG wishes to commend the sterling efforts of agency staff in conducting field programs, data collection and management. In addition, the professionalism shown by past and present members of the SRA Team at the MDBC, in all matters related to the delivery of quality-assured data and outputs, has been outstanding. The only significant problem with conduct of the Audit has been in regard to data for the Hydrology Theme.
7.3.2 Hydrology Long delays in delivery of hydrological data were experienced in 2007, allowing little time for comprehensive quality assurance and interpretation. As a result, little progress has been made since the SRA Pilot Audit (2002–03) in expanding the capacity of the Hydrology Theme to incorporate data from upper catchments or other areas beyond existing gauging stations, other than for Victoria. ISRAG is disappointed by the lack of progress, and recommends that the issues should be addressed urgently for future reports. Differences exist between jurisdictions in the bases for hydrological modelling. Some of the hydrological models used incorporated the influence of farm dams and groundwater abstractions, and others did not. In addition, data from Queensland differed from those of other State jurisdictions, in that all abstractions in the ‘current’ scenario were maximized. This misrepresents the effect of diversions on the current flow regime, and could make SRA hydrological assessments appear worse than they should be. The data may reflect the potential effect of full diversions, but the basis for assessment is not consistent with data from other parts of the Basin. In addition, more consistency is desirable between the SRA and the CSIRO Murray-Darling Basin Sustainable Yield Project. ISRAG recommends that these issues should be resolved in time for the next round of reporting.
7.3.3 Fish The need for a capacity to measure resilience leads ISRAG to suggest fish population recruitment (the accrual of mature individuals to populations) as a potential indicator. Threshold sizes at maturity should be established for all species to determine the proportions of recruits by species, Valleys and Zones. To enable interpretation, the Fish Taskforce should classify Valleys and Zones according to their significance for recruitment in each species. Development of the Diagnostic Index remains incomplete. Its potential value for SRA Report 2 in assessing mechanisms associated with poor condition, adding information on resilience and complementing the SR Fish Index should be examined by reviewing the integration of metrics and the ‘Intolerance’ lists, with advice from the Fish Taskforce. 363
Uncertainties about variation in statistical power in fish sampling and applications of the Protocol should be resolved by planned experimental assessments of data from State agency field teams. Taxonomic refinements will be required as Basin fish communities are further studied. The structure of Galaxias, Hypseleotris, Retropinna and other genera is under review, and changes will require revision of Reference Condition for Fish, perhaps with back-calculation of indices.
7.3.4 Macroinvertebrates Development of the Filters approach to Reference Condition assessment was conducted rapidly in 2006–07, with comparative testing using AUSRIVAS, and the team responsible is to be commended for their work. Some further work is needed, however, to refine the Filters method and to incorporate probabilities of occurrence in analyses. Minor improvements to quality assurance in taxonomic identification and data management are underway. The absence of abundance data, and data for larger invertebrates (e.g. crayfish, mussels), are significant limitations for this Theme. Plans to resolve these issues need to be expedited in time for the third round of macroinvertebrate assessment.
7.3.5 Quality Assurance and Quality Control Agreement between field site locations and the requirements of Field Site Sample Plans was satisfactory, given the high incidence of dry sites associated with drought. Compliance with sampling site numbers generally was high. The difficulties of fish sampling in the Castlereagh Lowland Zone had implications for the Audit in that Valley. Macroinvertebrate sampling sites in the Lowland and Slopes Zones were few, and results there should be regarded with some caution. In the Namoi Valley, only 25 of 35 required sites were sampled for macro- invertebrates, and only 44% of sites in the Slopes Zone were sampled. The effect on the Valley Condition rating probably is minimal, but this will be reviewed when the Filters method has been further refined. Checks to ensure adequate quality in primary data, derived variables, metrics, indicators, indices and Expert Rule outputs have been built into the SRA data-management process during 2006–07. Introduction of an improved SRA Data Acceptance Protocol has revealed 28 ‘Error’ and 25 ‘Warning’ notifications, most of them trivial. On two occasions, replacement of data sets was necessary. The Protocol has led to improved data quality and has engendered high levels of confidence in final data for all Themes. There is some variation within jurisdictions in sampling protocols for macroinvertebrates, and to a lesser extent fish. Further checking is needed also for the provenance of hydrology data and models. ISRAG recommends that a continuing effort be made to standardise protocols where practicable.
7.3.6 Sampling and reporting frequency The value, cost-benefit and interpretability of more intensive data collection should be considered. Increased sampling in time and space would allow Audit reporting at smaller spatial scales, with greater frequency. ISRAG recommends that the options be scoped in 2008, with statistical evaluations balancing cost and effort against levels of confidence at a range of spatial scales (sub- catchment to Valley) and reporting frequencies (1-3 yearly). 364
7.3.7 Goals and targets ISRAG wishes to raise the issue of the broader context of the Audit and the need for goals/targets to report against at Valley to Basin scales. The SRA is an audit in the sense of ‘an official inspection and report on a system or process’. It gathers and analyses data on biophysical components, reports on the condition of these components and integrates this information as an assessment of Ecosystem Health. It also inspects and reports on the conduct of the Audit itself. Ecosystem Health assessments are made relative to a benchmark, Reference Condition, represent- ing the status of the ecosystem when in good health. Subsequent reports will indicate the direction and magnitude of changes over time. There are several ways to define a benchmark, but in the absence of a ready alternative one, the SRA has adopted the Reference Condition, as a hypothetical reconstruction of the components of the ecosystem as they would have been in the absence of significant human impacts. ISRAG is concerned that the SRA, with other programs managing and monitoring aspects of river health in the Murray-Darling Basin, is proceeding without clear long-term goals or a vision for desired outcomes. It would be preferable if management was directed at clear, measurable, community-agreed objectives for ecosystem health, at appropriate scales. If targets were devel- oped for Valleys, surveillance monitoring programs like the SRA and The Living Murray could report quantitatively against them. ISRAG strongly recommends that a process be initiated to define clear, quantitative goals for comprehensive river-health management in the Murray-Darling Basin. These should be defined at a range of scales in time (years to decades) and space (single assets to Valleys), with due regard for the likely impacts of future climate change. They should be based on a practical vision of the desired future state of ecosystems in the Basin, and should have broad community, government and scientific support. 365
8. References Breckwoldt R, R Boden, J Andrew (eds) 2004. The Darling. Murray-Darling Basin Commission: Canberra. Chessman BC 2003. New sensitivity grades for Australian river macroinvertebrates. Marine and Freshwater Research 54: 95-103. Chessman BC, MJ Royal 2004. Bioassessment without reference sites: use of environmental filters to predict natural assemblages of river macroinvertebrates. Journal of the North American Benthological Society 23: 599-615. Chessman BC, LA Thurtell, MJ Royal 2006. Bioassessment in a harsh environment: A comparison of macroinvertebrate assemblages at reference and assessment sites in an Australian inland river system. Environmental Monitoring and Assessment 119: 303-330. Cottingham P, A Horne, D Crook, T Hillman, J Roberts, A Sharpe, M Stewardson 2008. Assessment of potential summer releases along the lower Campaspe River. Report to the North-Central Catchment Authority. Peter Cottingham and Associates: Melbourne. Crabb P 1997. Murray-Darling Basin Resources. Murray-Darling Basin Commission: Canberra. Davies PE 2000. Development of a national river bioassessment system (AUSRIVAS) in Australia. pp113-124 In Wright J, D Sutcliffe, M Furse (eds), Assessing the Biological Quality of Fresh Waters. Freshwater Biological Association: Cumbria, UK. Gilligan D 2005. Fish communities of the Lower Murray-Darling Catchment: Status and trends. DPI Final Report Series 83: Cronulla, NSW. Gooderham J, E Tsyrlin 2002. The Waterbug Book. A Guide to the Freshwater Macro- invertebrates of Temperate Australia. CSIRO Publishing. Gray BJ 2004. Australian River Assessment System: National Guidelines for AusRivAS Metadata. Department of the Environment and Heritage, Monitoring River Health Initiative Technical Report Number 40, Canberra. Harris JH, PC Gehrke (eds) 1997. Fish and Rivers in Stress. The NSW Rivers Survey. NSW Fisheries Office of Conservation, Cronulla, and the Cooperative Research Centre for Fresh- water Ecology, Canberra, in association with the NSW Resource and Conservation Assessment Council. Harris JH, R Silveira 1999. Large-scale assessments of river health using an Index of Biotic Integrity with low-diversity fish communities. Freshwater Biology 41: 235-252. Hawking JH, FJ Smith 1997. Colour Guide to Invertebrates of Australian Inland Waters. Identification Guide 8, Cooperative Research Centre for Freshwater Ecology: Albury. Hearnshaw EJS, R Cullen, KFD Hughey 2005. Ecosystem health demystified. An ecological concept determined by economic means. Economics and Environment Network Conference 4-6 May 2005. Australian National University, Canberra. Accessed March 2008: http://eeen.anu.edu.au/e05prpap/hearnshaw.doc. Junk WJ, PB Bayley, RE Sparks 1989. The flood pulse concept in river-floodplain systems. Canadian Journal of Fisheries and Aquatic Sciences 106: 110–127. Karr JR 1981. Assessment of biotic integrity using fish communities. Fisheries 6: 21-27. 366
Karr JR, EW Chu 1997. Biological Monitoring and Assessment: Using Multimetric Indexes effectively. EAPA 235-R97-001. Office of Policy, Planning, and Evaluation, US Environ- mental Protection Agency: Washington, DC. Lintermans M 2007. Fishes of the Murray-Darling Basin: An Introductory Guide. Publication 10/07, Murray-Darling Basin Commission: Canberra. Mackay N, D Eastburn (eds) 1990. The Murray. Murray-Darling Basin Commission: Canberra. McCune B, JB Grace 2002. Analysis of Ecological Communities. MjM Software, Oregon. MDBC 2003a. Environmental Implications of Drought for Management of the River Murray System. Report of a Workshop conducted by the Murray-Darling Basin Commission. Technical Report 17/03. Murray–Darling Basin Commission: Canberra. MDBC 2003b. Native Fish Strategy for the Murray-Darling Basin 2003-2013. Murray-Darling Basin Commission: Canberra. MDBC 2004a. Fish Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 06/04. Murray–Darling Basin Commission: Canberra. MDBC 2004b. Macroinvertebrate Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 07/04. Murray–Darling Basin Commission: Canberra. MDBC 2004c. Hydrology Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 08/04. Murray–Darling Basin Commission: Canberra. MDBC 2004d. Water Processes Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 09/04. Murray–Darling Basin Commission: Canberra. MDBC 2004e. Physical Habitat Theme Pilot Audit Technical Report – Sustainable Rivers Audit. MDBC Publication 10/04. Murray–Darling Basin Commission: Canberra. MDBC 2004f. Sustainable Rivers Audit Program. MDBC Publication 38/04. Murray–Darling Basin Commission: Canberra. MDBC 2007a. Sustainable Rivers Audit Protocols – Approved Manual for Implementation Period 4: 2007–08. Released September 2007. Murray–Darling Basin Commission: Canberra. MDBC 2007b. Water Audit Monitoring Report 2005/06. Murray–Darling Basin Commission: Canberra. MDBC 2008. Murray System Drought Update. Issue 12, March 2008. Murray–Darling Basin Commission: Canberra. Negnevitsky M 2002. Artificial Intelligence. A Guide to Intelligent Systems. Pearson Education. Puckridge JT, KF Walker 1990. Reproductive biology and larval development of a gizzard shad, Nematalosa erebi (Günther) (Dorosomatinae: Teleostei), in the River Murray, South Australia. Australian Journal of Marine and Freshwater Research 41: 695-712. SKM 2004. Priority Ranking for Improved Stream Management. Formulation of Hydrologic Stress Index. Sinclair Knight Merz: Armadale, Victoria. SKM 2005. Development of a Flow Stressed Ranking Procedure. Final Report to Department of Sustainability and Environment, Victoria. Sinclair Knight Merz: Armadale, Victoria. Thoms MC, F Sheldon, J Roberts, J Harris, TJ Hillman 1996. Scientific Panel Assessment of Environmental Flows for the Barwon-Darling River. NSW Department of Land and Water Conservation, Sydney. 367
Thoms MC, F Sheldon, P Crabb 2004. A hydrological perspective on the Darling River, pp. 332-347 In Breckwoldt R, R Boden, J Andrew (eds), The Darling. Murray-Darling Basin Commission: Canberra Vlok A, N Jiricek, K Travis, R Hardy 2007. Upper Avoca Catchment Action Plan—Strategy Development. Report by Alluvium and HLA for North-Central Catchment Management Authority. Huntly, Victoria. Walker KF 1992. A semi-arid lowland river: the River Murray, Australia. In PA Calow, GE Petts (eds), The Rivers Handbook, v1. Blackwell Scientific, Oxford: 472-492. Walker KF 2006. Serial weirs, cumulative effects: the Lower River Murray, Australia. In R Kingsford (ed.), The Ecology of Desert Rivers. CUP: 248-279. Walsh C, M Stewardson, J Stein, S Wealands 2007. Sustainable Rivers Audit Filters Project Stage 2. Report to Murray-Darling Basin Commission, August 2007. 55p. Whittington J, J Coysh, P Davies, F Dyer, B Gawne, I Lawrence, P Liston, R Norris, W Robinson, M Thoms 2001. Development of a Framework for the Sustainable Rivers Audit. A Report to the Murray-Darling Basin Commission. Cooperative Research Centre for Fresh- water Ecology, Canberra: Technical Report 8/2001. Williams WD 1980. Australian Freshwater Life, 2nd ed. Macmillan. Young WJ (ed.) 2001. Rivers as Ecological Systems: the Murray-Darling Basin. Murray-Darling Basin Commission: Canberra. 368
9. Appendices
9.1 Appendix I: Expert Rules tables Expert Rules were used at three levels of assessment (Section 2.3.2): (1) Indicator Expert Rules determine the values of indicators from metrics (Hydrology and Fish Themes only), (2) Index Expert Rules determine the values of indices from indicators (Hydrology, Fish and Macroinvertebrate Themes), and (3) Health Expert Rules determine Ecosystem Health from all Theme indices. This Appendix contains tabulations of the rule sets used at each level, arranged by Themes. In the tables, H = High, M = Medium and L = Low. In some cases, zero values also are allowed.
Indicator Expert Rules (a) Hydrology Theme These are rules to derive the Gross Volume (GV) indicator from the mean annual discharge metrics (MNAQ, MDAQ), and the Low- and Zero-Flow Events (LZFE) indicator from the flow- duration metrics (LF, PZ). See Section 3.2.4.
Annual Discharge Metrics Gross Volume Indicator Mean Median GV MNAQ MDAQ
H H 10 H M 7.5 H L 5 M H 6.5 M M 4.5 M L 2.5 L H 3 L M 1.5 L L 0
Metrics Low- and Zero-Flow Events Indicator LF PZ LZFE
H H 10 H M 7 H L 4 M H 8 M M 5 M L 2 L H 6 L M 3 L L 0 369
(b) Fish Theme These are rules to derive the Expectedness (SR–FIe) and Nativeness (SR–FIn) Indicators from five metrics (OE, OP, propn_N_abund, propn_N_sp, propn_N_biom). See Section 3.3.4. The rules for deriving SR-FIn are in two versions, depending on whether the Reference Condition for Fish list (RC–F ) contains a low (≤5) or high (>5) number of species.
Metrics Expectedness Indicator OE OP SR–FIe
H H 100 H M 70 H L 40 M H 80 L H 60 M M 50 M L 20 L M 30 L L 0
Metrics Nativeness propn_ propn_ propn_ Indicator N N N SR–FIn _abund _sp _biom
RC-F list ≤5 H H H 100 H L H 80 H H L 60 L H H 60 L H L 40 H L L 20 L L H 20 L L L 10
RC-F list >5 H H H 100 H L H 80 H H L 60 L H H 60 L H L 40 H L L 30 L L H 30 L L L 10
(c) Macroinvertebrate Theme Indicator Expert Rules were not required for this Theme.
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Index Expert Rules (a) Hydrology Theme These are rules to derive the Hydrology Index (SR–HI) from five indicators (HFE, LZFE, V, S, GV). See Section 3.2.5.
Indicators Hydrology Condition Index HFE LZFE V S GV SR–HI
H H H H H 100 H H H H L 93 H H H L H 87 H H H L L 80 H H L HH 80 H H L H L 73 H H L L H 67 H H L L L 60 H L H H H 73 H L H H L 67 H L H L H 60 H L H L L 53 H L L HH 53 H L L HL 47 H L L L H 40 H L L L L 33 L H H H H 67 L H H H L 60 L H H L H 53 L H H L L 47 L H L HH 47 L H L HL 40 L H L L H 33 L H L L L 27 L L H H H 40 L L H H L 33 L L H L H 27 L L H L L 20 L L L HH 20 L L L HL 13 L L L L H 7 L L L L L 0
371
(b) Fish Theme These are rules to derive the Fish Index (SR–FI) from the Expectedness (SR–FIe) and Nativeness (SI-FIn) indicators. See Section 3.3.6.
Indicators Fish Index Expectedness Nativeness SR–FI SR–FIe SR–FIn
H H 100 H L 70 L H 40 L L 0
(c) Macroinvertebrate Theme These are rules to derive the Macroinvertebrate Index (SR–MI) from the Filters OE and SIGNAL Filters OE metrics. See Section 3.4.5.
Metrics Macro- invertebrate Index Filters Filters SR–MI OE SIGNAL OE
H H 100 H M 85 H L 70 M H 65 M M 50 M L 40 L H 30 L M 20 L L 10 0 0 0
Health Expert Rules This Table shows the rationale used to determine Ecosystem Health from Condition assessments in the Hydrology, Fish and Macroinvertebrate Themes. See Section 2.3.2. Two sample applications are:
• Namoi Upland Zone: Fish, Macroinvertebrate and Hydrology Condition rated Good, Poor and Good, respectively. Ecosystem Health = Moderate (Case 15).
• Campaspe Valley: Fish, Macroinvertebrate and Hydrology Condition rated Extremely Poor, Poor and Moderate, respectively. Ecosystem Health = Very Poor (Case 99). 372
Condition Ecosystem Health Case Macro- Fish Hydrology SR-EH Label invertebrates
1 Good Good Good 100.0 2 Good Good Moderate 96.5 3 Good Good Poor 93.0 4 Good Good Very Poor 89.0 5 Good Moderate Good 87.5 Good 6 Moderate Good Good 87.5 Health 7 Good Good Extremely Poor 85.0 8 Good Moderate Moderate 84.3 9 Moderate Good Moderate 84.3 10 Moderate Moderate Good 81.3 11 Good Moderate Poor 81.0 12 Moderate Good Poor 81.0 13 Good Moderate Very Poor 77.5 14 Moderate Good Very Poor 77.5 15 Good Poor Good 75.0 16 Moderate Poor Good 75.0 17 Poor Good Good 75.0 18 Poor Moderate Good 75.0 19 Good Moderate Extremely Poor 74.0 20 Moderate Good Extremely Poor 74.0 21 Good Poor Moderate 72.0 22 Poor Good Moderate 72.0 23 Moderate Moderate Moderate 71.9 24 Moderate Moderate Poor 69.5 Moderate 25 Good Poor Poor 69.0 Health 26 Poor Good Poor 69.0 27 Moderate Moderate Very Poor 66.5 28 Good Poor Very Poor 66.0 29 Poor Good Very Poor 66.0 30 Moderate Moderate Extremely Poor 63.5 31 Good Poor Extremely Poor 63.0 32 Poor Good Extremely Poor 63.0 33 Good Very Poor Good 62.5 34 Very Poor Good Good 62.5 35 Good Very Poor Moderate 59.8 36 Very Poor Good Moderate 59.8 37 Moderate Poor Moderate 59.5 Poor 38 Poor Moderate Moderate 59.5 Health 39 Moderate Poor Poor 58.0 40 Poor Moderate Poor 58.0 41 Good Very Poor Poor 57.0 42 Very Poor Good Poor 57.0 43 Very Poor Moderate Good 57.0 44 Moderate Poor Very Poor 55.5 45 Poor Moderate Very Poor 55.5 46 Good Very Poor Very Poor 54.3 47 Very Poor Good Very Poor 54.3 48 Poor Poor Good 53.0 49 Moderate Poor Extremely Poor 53.0 50 Poor Moderate Extremely Poor 53.0 373
Condition Ecosystem Health Case Macro- Fish Hydrology SR-EH Label invertebrates 51 Good Very Poor Extremely Poor 51.5 52 Very Poor Good Extremely Poor 51.5 53 Good Extremely Poor Good 50.0 54 Extremely Poor Good Good 50.0 55 Moderate Very Poor Moderate 48.1 56 Very Poor Moderate Moderate 48.1 57 Good Extremely Poor Moderate 47.5 58 Extremely Poor Good Moderate 47.5 59 Poor Poor Moderate 47.0 60 Poor Poor Poor 47.0 61 Moderate Very Poor Poor 46.3 62 Very Poor Moderate Poor 46.3 63 Moderate Very Poor Good 45.3 64 Good Extremely Poor Poor 45.0 65 Poor Poor Very Poor 45.0 66 Extremely Poor Good Poor 45.0 67 Moderate Very Poor Very Poor 43.9 68 Very Poor Moderate Very Poor 43.9 69 Poor Poor Extremely Poor 43.0 70 Good Extremely Poor Very Poor 42.5 71 Extremely Poor Good Very Poor 42.5 72 Moderate Very Poor Extremely Poor 41.5 73 Very Poor Moderate Extremely Poor 41.5 74 Good Extremely Poor Extremely Poor 40.0 75 Extremely Poor Good Extremely Poor 40.0 76 Moderate Extremely Poor Good 39.0 Very Poor 77 Extremely Poor Moderate Good 39.0 Health 78 Moderate Extremely PoorModerate 36.8 79 Extremely Poor Moderate Moderate 36.8 80 Poor Very Poor Moderate 36.5 81 Very Poor Poor Moderate 36.5 82 Poor Very Poor Poor 35.5 83 Very Poor Poor Poor 35.5 84 Moderate Extremely Poor Poor 34.5 85 Extremely Poor Moderate Poor 34.5 86 Poor Very Poor Very Poor 33.5 87 Very Poor Poor Very Poor 33.5 88 Moderate Extremely Poor Very Poor 32.3 89 Extremely Poor Moderate Very Poor 32.3 90 Poor Very Poor Extremely Poor 31.5 91 Very Poor Poor Extremely Poor 31.5 92 Moderate Extremely Poor Extremely Poor 30.0 93 Extremely Poor Moderate Extremely Poor 30.0 94 Poor Very Poor Good 28.0 95 Poor Extremely PoorGood 28.0 96 Very Poor Poor Good 28.0 97 Extremely Poor Poor Good 28.0 98 Poor Extremely PoorModerate 26.0 99 Extremely Poor Poor Moderate 26.0 100 Very Poor Very Poor Moderate 25.8 374
Condition Ecosystem Health Case Macro- Fish Hydrology SR-EH Label invertebrates 101 Very Poor Very Poor Poor 24.5 102 Poor Extremely PoorPoor 24.0 103 Extremely Poor Poor Poor 24.0 104 Very Poor Very Poor Very Poor 22.6 105 Very Poor Very Poor Good 22.3 106 Poor Extremely Poor Very Poor 22.0 107 Extremely Poor Poor Very Poor 22.0 108 Very Poor Very Poor Extremely Poor 20.8 109 Poor Extremely Poor Extremely Poor 20.0 110 Extremely Poor Poor Extremely Poor 20.0 111 Very Poor Extremely Poor Good 16.5 112 Extremely Poor Very Poor Good 16.5 113 Very Poor Extremely Poor Moderate 15.0 114 Extremely Poor Very Poor Moderate 15.0 115 Very Poor Extremely Poor Poor 13.5 116 Extremely Poor Very Poor Poor 13.5 117 Very Poor Extremely Poor Very Poor 11.8 118 Extremely Poor Very Poor Very Poor 11.8 Extremely Poor 119 Very Poor Extremely Poor Extremely Poor 10.0 Health 120 Extremely Poor Very Poor Extremely Poor 10.0 121 Extremely Poor Extremely Poor Good 5.0 122 Extremely Poor Extremely Poor Moderate 4.0 123 Extremely Poor Extremely Poor Poor 3.0 124 Extremely Poor Extremely Poor Very Poor 1.5 125 Extremely Poor Extremely Poor Extremely Poor 0.0
375
9.2 Appendix 2: Fish and macroinvertebrate sampling sites Shows the numbers of sites required for the Fish and Macroinvertebrate Themes (R), the numbers of sites sampled (S) and differences between the respective pairs (D)
Fish Macroinvertebrates Valley Zone R S D R S D Slopes 8 8 13 13 Avoca Lowland 10 10 22 22 Total 18 18 35 35 Montane 7 7 3 3 Upland 7 7 4 4 Border Rivers Slopes 7 7 17 16 -1 Lowland 7 7 11 11 Total 28 28 35 34 -1 Slopes 8 10 +2 11 11 Broken Lowland 10 9 -1 24 24 Total 18 19 +1 35 35 Upland 7 7 10 10 Campaspe Slopes 7 7 13 13 Lowland 7 7 12 12 Total 21 21 35 35 Upland 7 7 9 7 -2 Castlereagh Slopes 7 7 13 5 -8 Lowland 7 4 -3 13 6 -7 Total 21 18 -3 35 18 -17 Slopes 8 8 16 16 Condamine Lowland 10 11 +1 19 19 Total 18 19 +1 35 35 Upper 7 7 5 5 Darling Middle 7 7 18 20 +2 Lower 7 7 12 13 +1 Total 21 21 35 38 +3 Upland 7 7 7 6 -1 Goulburn Slopes 7 7 10 10 Lowland 7 7 18 18 Total 21 21 35 34 -1 Montane 7 7 6 7 +1 Upland 7 7 6 6 Gwydir Slopes 7 7 12 13 +1 Lowland 7 7 11 11 Total 28 28 35 37 +2 Upland 7 7 12 11 -1 Kiewa Slopes 7 7 15 16 +1 Lowland 7 7 8 8 Total 21 21 35 35 Montane 7 7 3 3 Upland 7 8 +1 7 7 Lachlan Slopes 7 6 -1 11 11 Lowland 7 7 14 14 376
Total 28 28 35 35 Upland 3 3 Loddon Slopes 8 9 +1 9 8 -1 Lowland 10 10 23 23 Total 18 19 +1 35 34 -1 Upland 7 7 10 10 Macquarie Slopes 7 7 8 8 Lowland 7 7 17 17 Total 21 21 35 35 Montane 7 7 12 11 -1 Mitta Mitta Upland 7 7 14 12 -2 Slopes 7 7 9 9 Total 21 21 35 32 -3 Montane 7 7 8 8 Murray, Upper Upland 7 7 12 12 Slopes 7 7 15 14 -1 Total 21 21 35 34 -1 Upper 7 7 23 23 Murray, Central Middle 7 7 8 8 Lower 7 7 4 4 Total 21 21 35 35 Upper 7 7 18 16 -2 Middle 7 7 7 7 Murray, Lower Lower 7 7 2 2 Mt Lofty 7 7 8 8 Total 28 28 35 33 -2 Montane 7 7 11 11 Upland 7 7 7 7 Murrumbidgee Slopes 7 7 7 7 Lowland 7 7 10 10 Total 28 28 35 35 Montane 7 7 3 3 Upland 7 7 8 7 -1 Namoi Slopes 7 7 16 7 -9 Lowland 7 7 8 8 Total 28 28 35 25 -10 Montane 7 5 -2 3 3 Upland 7 7 9 9 Ovens Slopes 7 7 13 13 Lowland 7 7 10 10 Total 28 26 -2 35 35 Paroo Lowland 18 18 35 35 Total 18 18 35 35 Slopes 8 8 8 8 Warrego Lowland 10 8 -2 27 27 Total 18 16 -2 35 35 Slopes 9 9 14 13 -1 Wimmera Lowland 9 8 -1 21 21 Total 18 17 -1 35 34 -1