Inland Waters Theme Report

Australia State of the Environment Report 2001 (Theme Report)
Prepared by: Jonas Ball, Sinclair Knight Merz Pty Limited, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06750 7

Aquatic ecosystems (continued)

Condition of aquatic ecosystems (continued)

Aquatic fauna

  • Freshwater native fish
  • Inland waterbirds
  • Distribution of frogs
  • Crayfish and platypus
  • River health as measured by AusRivAS
  • Messages on the condition of aquatic ecosystems
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    Freshwater native fish

    Over 200 freshwater fish species have been identified in Australia, with new species continuing to be discovered. Native fish can be affected by habitat destruction and modification, pollution, overexploitation, flow regulation, barriers to movement and the introduction of exotic species.

    In comparison to marine species, most Australian freshwater fish species have experienced a reduction in distribution and abundance over the past 200 years (Wager & Jackson 1993). In New South Wales, 6% of freshwater fish species have been listed as threatened under the Fisheries Management Act 1994 whereas less than 1% of marine fish species are considered threatened (NSW EPA 2001). To date, no freshwater fish species are known to have become extinct in Australia since European settlement (ASFB 2000). However, a number of species have suffered serious reductions in range or abundance. Table 37 lists the status of threatened freshwater fish species nationally. Despite widespread recognition of the issue, the decline of native fish species has not been extensively studied at a national level, and data do not exist for the whole of Australia.

    Table 37: Conservation status of Australian freshwater fish
    Scientific name Common name Status under the EPBC ActA
    Extinct No species  
    Endangered    
    Chlamydogobius micropterus Elizabeth Springs goby E
    Galaxias fontanus Swan galaxias E
    Galaxias fuscus Barred galaxias E
    Galaxias johnstoni Clarence galaxias E
    Galaxias pedderensis Pedder galaxias E
    Maccullochella macquariensis Trout cod E
    Maccullochella ikei Eastern cod E
    Maccullochella peelii mariensis Mary River cod E
    Melanotaenia eachamensis Lake Eacham rainbowfish E
    Nannoperca oxleyana Oxleyan pigmy perch E
    Scaturiginichthys vermeilipinnisv Red finned blue-eye E
    Bidyanus bidyanus Silver perch  
    Galaxias tanycephalus Saddled galaxias V
    Macquaria australasica Macquarie perch  
    Mogurnda clivicola Flinders Ranges gudgeon V
    Nannatherina balstoniv Balston's pygmy perch  
    Percichthyidae n.sp. Bloomfield River cod  
    Pseudomugil mellis Honey blue-eye V
    Potentially threatened    
    Craterocephalus dalhousiensis Dalhousie hardyhead  
    Craterocephalus fluviatilis Murray hardyhead V
    Craterocephalus gloveri Glover's hardyhead  
    Galaxias parvus Swamp galaxias  
    Galaxiella pusilla Dwarf galaxias V
    Mordacia praecox Non-parasitic lamprey  
    Neosilurus gloveri Dalhousie catfish  
    Edelia obscura Yarra pigmy perch V
    Pristis microdon Freshwater sawfish V
    Prototroctes maraena Australian grayling V
    Indeterminate    
    Ophisternon candidum Blind cave eel V

    A Species listed under the EPBCA (1999) are also denoted. E = endangered; V= vulnerable.

    Source: ASFB 2000.

    Case study 12: The New South Wales Rivers Survey

    The New South Wales Rivers Survey (Harris & Gehrke 1997) provides an indication of the condition of fish communities in regulated inland river systems. Data collected over two years at 80 sampling sites in four regions of New South Wales were compared to an earlier study (Llewellyn 1983).

    Sixteen of the 55 native freshwater fish species that were found in rivers in the 1970s and 1980s were not found in the latest survey (Schiller et al. 1997) (Table 38). Four of these species are currently considered endangered, and several more species were rated by the IUCN as endangered or vulnerable. The Murray region, in particular, had a reduced abundance of native species, with significant declines in major commercial/recreational angling species such as Murray cod (Maccullochella peelii peelii) and freshwater catfish (Tandanus tandanus) (Schiller et al . 1997). The decline in native fish populations was not limited to the Murray region.

    Table 38: Qualitative comparisons of native freshwater fish found in the New South Wales Rivers Survey with previous records
    Species recorded within each region by Llewellyn (1983) not caught during New South Wales Rivers Survey (1997) Species caught within each region during New South Wales
    Rivers Survey (1997) not recorded by Llewellyn (1983)
    Species Common name Species Common name
    Darling      
    Ambassis castelnaui Western chanda perch Ambassis agassizii Olive perchlet
    Craterocephalus fluviatilis A Murray hardyhead Philypnodon grandiceps Flathead gudgeon
    Mogurnda adspersaA Purple-spotted gudgeon    
    Murray      
    Ambassis agassizii Olive perchlet Craterocephalus stercusmuscarum Flyspecked hardyhead
    Anguilla australis Short-finned eel Gadopsis bispinosus Two-spined blackfish
    Galaxias rostratusB Murray jollytail Galaxias brevipinnus Climbing galaxias
    Maccullochella macquariensis A Trout cod Leipotherapon unicolor Spangled perch
    Maccullochella peelii Murray cod Melanotaenia fluvialtilis Crimson-spotted rainbowfish
    Mogurnda adspersaA Purple-spotted gudgeon    
    Mordacia mordax Shortheaded lamprey    
    Nannoperca australis Southern pygmy perch    
    Tandanus tandanus Freshwater catfish    
    North Coast      
    Craterocephalus fluviatili sA Murray hardyhead Ambassis agassizii Olive perchlet
    Galaxias maculatus Common jollytail    
    Leipotherapon unicolor Spangled perch    
    Macculochella ikeiA Eastern cod    
    Nannoperca oxleyanaA Oxleyan pygmy perch    
    Rhadinocentrus ornatus Softspined rainbowfish    
    South Coast      
    Hypseleotris sp. Carp gudgeon Pseudaphritis urvilii Congolli
    Macquaria australasica Macquarie perch    
    Mordacia mordax Shortheaded lamprey    
    Pseudomugil signifer Southern blue-eye    

    A IUCN classification 'endangered'.
    B IUCN classification 'vulnerable'.

    Source: Schiller et al. 1997.

    Inland waterbirds [IW Indicator 6.4]
  • Significant wetlands for waterbirds in the Murray-Darling Basin
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    The loss of riverine and wetland habitat affects the distribution and abundance of inland waterbirds. The Action Plan for Australian Birds (Garnett & Crowley 2000) provides a national overview of the conservation status of Australia's waterbirds. Of the 314 birds species in the Action Plan, 18 species are dependent on inland waters for part or all of their life history (Garnett & Crowley 2000). Since European settlement, one waterbird species is known to have become extinct, four species are considered threatened and five species are classified as near threatened (Garnett & Crowley, 2000).

    Table 39 summarises the current status of listed inland waterbird species as described in the Action Plan.

    Table 39: Status, names and comments of Australian bird taxa listed in the Action Plan for Australian Birds
    Status Species Comments
    Extinct Lewin's rail (Western Australian) There have been no records of this subspecies since 1932. It is believed to have been vulnerable to extinction during times of drought, a situation exacerbated by the draining and/or burning of swamps in south-western Australia for agriculture.
    Vulnerable Australasian bittern
    Painted snipe (Australian)
    Hooded plover (eastern)
    Red goshawk
    Water diversion, drainage of wetlands, overgrazing, clearance of vegetation for agriculture, unsuitable fire regimes and predation are the range of processes contributing to the vulnerable status of these species.
    Near threatened Cotton pygmy-goose (Australian)
    Little bittern (Australasian)
    Lewin's rail (eastern)
    Hooded plover (western)
    Grey falcon
    Habitat loss through wetland drainage, river diversion, salinisation and predation are the main causes for species losses.Benefits through creation of new wetlands, such as Ross River Dam and Tinaroo Dam are having positive impacts on species numbers for the Cotton pygmy-goose.
    Least concern Magpie goose
    Blue-billed duck
    Freckled duck
    Radjah shelduck (Australian)
    Black bittern (Australasian)
    Black-necked stork
    Sarus crane (Australian)
    Latham's snipe
    In general, the taxa listed as of least concern within the Action Plan have reduced numbers or range primarily as a result of wetland drainage, wetland or waterway degradation from disturbance (clearance of creek side vegetation, introduced fish, cattle grazing) and/or salinisation. Reduced numbers of magpie geese and Latham's snipe are also attributed to past hunting.

    Source: Garnett & Crowley 2000.

    Significant wetlands for waterbirds in the Murray-Darling Basin

    Since 1983, systematic aerial surveys have been flown over the Murray-Darling Basin each year to count waterbirds (Kingsford et al. 1997). The aerial surveys cover 10% of the Basin and focus on wetlands greater than one hectare. Fifty-five wetlands in the Murray-Darling Basin supported 20 000 waterbirds or more (Kingsford et al. 1997). Thirty-one of these were lakes, swamps or dams. Seven wetlands supported more than 50 000 waterbirds, namely: Macquarie Marshes (191 000), Tandou Lake (86 000), Lake Wyara (85 000), Yantabulla Swamp (80 000), Lake Alexandrina (75 000), Gwydir wetlands (65 000) and the Coorong (57 000). A further 33 lakes, swamps and dams that supported between 10 000 and 20 000 waterbirds were also identified. The most important factor affecting these wetlands' viability is water supply (Kingsford et al. 1997).

    Distribution of frogs [IW Indicator 6.2]

    The abundance and distribution of frogs over time is an important indicator of the health of aquatic ecosystems as frogs are sensitive to changes in their environment. The global populations of frogs have been in decline for a number of years and this trend is also evident among Australian frog populations. Australia currently has 208 recognised frog species, 27 of which are considered threatened (20 endangered and 7 vulnerable) (Environment Australia 2000).

    In response to declining frog populations Environment Australia has prepared the Action Plan for Australian Frogs (Environment Australia 2000). For most species, no definite causes of decline have been identified, and a number of threats are still being investigated. Some of these potential threats include loss and degradation of habitat, land use practices, hydrological changes, pollution (including pesticides), predation and disease (Environment Australia 2000). The chytrid fungus has been implicated as a significant cause in the decrease of some frog populations in Australia (Berger et al. 1998). The chytrid fungus has been found in populations in four main zones: a large east coast zone extending from Cooktown to Melbourne, a zone around Adelaide, a zone extending from Perth over most of the south-west of Western Australia and a newly detected zone in the central Kimberley region. Forty-six species of amphibians, including 13 threatened species of frogs, have been found to be infected with the fungus, which causes 100% mortality. The chytrid fungus is a significant threat to Australia's frog populations. (See http://www.jcu.edu.au/school/phtm/PHTM/frogs/chyspec.htm )

    The overall decline in frog species appears to be concentrated in eastern Australia with 24 of the 27 frog species identified as threatened in the Action Plan for Australian Frogs located in the eastern states. A summary of the status of endangered frog species and the conservation measures is presented below.

    • Three frogs are listed as endangered in New South Wales. The spotted tree frog (Litoria spenceri) is endangered due to habitat loss, changes to hydrology and the introduction of exotic species. A draft recovery plan for the species has been prepared (NPWS 1999a). The green and golden bell frog (Litoria aurea) has suffered a dramatic population decline and only a few coastal populations still survive. The loss of wetland habitats poses a threat to the remaining populations and a recovery plan is being prepared (NPWS 1999b). One major success story is recovery of the green and golden bell frog community at the Homebush Bay Olympic site, where numbers have quadrupled over the past 4 years.
    • Victoria's 26 frog species are all located within the highlands of central and eastern Gippsland. Under the Victoria's Flora and Fauna Guarantee Act 1988, action plans have been written for three of these species (NRE 2000). Human activities threatening these species include alpine recreation, timber harvesting, sedimentation of streams and the introduction of exotic species.
    • Seventy-eight frog species are found in Western Australia and many are listed as threatened under the West Australian Wildlife Conservation Act 1950 (Environment Australia 1999).
    • Eleven frog species, three of which are endemic, exist in Tasmania (PWS 2000). Only one of these species is listed as vulnerable . Frog diseases and pathogens transported from Queensland via fruit are a risk to native frog species in Tasmania (PWS 2000).
    • The South Australian EPA frog census results have shown that the abundance of species in the state has remained relatively constant with the exception of the spotted grass frog (Limnodynastes tasmaniensis) whose abundance has decreased over three years (SA EPA 2000).
    Crayfish and platypus

    The abundance and distribution of freshwater crayfish and platypus are other indicators of the health of Australian inland waters.

    Australia's crayfish species occupy a variety of habitats ranging from riparian zones to cool mountain streams and include species commonly referred to as yabbies, marron and lobsters. The distribution and abundance of many crayfish appear to have declined, as most freshwater crayfish in Australia are found in developed areas (Horwitz 1990).

    The Tasmanian giant freshwater crayfish is the largest freshwater crayfish in the world, reaching four to five kilograms in size and living for at least 30 years. They were once found in most northern rivers draining into Bass Strait at altitudes below 400 m (Hamr 1990). Today their distribution is patchy, and significant declines in populations have occurred due to habitat disturbance and overfishing in combination with the species' slow growth and long reproductive processes (Hamr 1990). The species is (as at June 2001) the only crustacean listed under the Environmental Protection and Biodiversity Conservation Act 1999 as 'threatened'. Additionally it is declared as a 'protected fish' under the Inland Fisheries Act 1995 and has a recovery plan. Four other species of crayfish were gazetted in August 2001.

    The Murray crayfish (Euastacus armatus) has the widest distribution of any of the spiny crayfish (members of the genus Eustacus and Astacopsis). Prior to the 1950s, Murray crayfish were found in the Murray River in South Australia and New South Wales, as well as its major tributaries in New South Wales and Victoria. Today, this species is considered critically endangered in South Australia (Keith Williams, pers. com.) and tight fishing regulations exist in New South Wales and Victoria because of a decline in crayfish stocks.

    Fishing pressure can significantly affect crayfish populations. A survey of Murray crayfish in the Murrumbidgee River in the Australian Capital Territory found that numbers were low and being affected by overfishing (Lintermans & Rutzou 1991). In 1991 the species was declared protected and the fishery closed to allow stocks to recover (Lintermans 1993). The fishing ban has had limited success with Murray crayfish numbers increasing, although most of the increases were at a single site.

    The burgeoning aquaculture industry also poses a threat to naturally occurring populations because the biological attributes of aquaculture species (such as their rapid growth) could threaten endemic species should they escape or be deliberately released (Merrick 1995). Some crayfish species have become established in areas out of their natural range, for example the Western Australian marron (Cherax tenuimanus) has become established in southern Victoria and the Southern Australian yabby (C. destructor) has become established in Western Australia.

    The platypus (Ornithorhynchus anatinus) is a unique mammal found only in eastern Australia (Scott & Grant 1997) and is regarded as an excellent biological indicator for the overall health of waterways (Francis 1999). The distribution of platypus ranges from as far north as Cooktown in Queensland to areas of New South Wales, Victoria and Tasmania. In South Australia, an introduced population exists on Kangaroo Island, but it is considered rare or extinct on the mainland.

    Population densities of platypus within its present range can vary markedly and are often linked to availability of suitable habitat. Loss of suitable habitat has been a contributing factor in declining population numbers and decreased distribution/range of platypus, and will continue to threaten the species (Turnbull 1998). Loss of suitable habitat can be caused by river regulation, water extraction, declining water quality, changes to riparian vegetation and changes in stream geomorphology due to sedimentation and erosion (Scott & Grant, 1997; Serena & Williams, 1998; Munday, 1999).

    Platypus are difficult to monitor in the wild because of their quiet, retiring nature and largely nocturnal habits. As a consequence, knowledge on the distribution of platypus is often patchy. Community-based surveys have been adopted by some organisations as a method of evaluating the status of platypus in many catchments (Rohweder & Baverstock 1999).

    There is a general belief that populations have declined or disappeared in many catchments in all states (e.g. Grant, 1998; Lunney et al. 1998; Rohweder & Baverstock 1999; APC 2001). The platypus is vulnerable because its range includes the most densely populated regions of Australia. Increased emphasis on further study and the inclusion of platypus in waterway management plans is required in order to retain their current status.

    River health as measured by AusRivAS [IW Indicator 6.1]
  • New South Wales (and Australian Capital Territory)
  • Northern Territory
  • Queensland
  • South Australia
  • Tasmania
  • Victoria
  • Western Australia
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    AusRivAS (Australian Rivers Assessment System) is a system based on riverine aquatic macroinvertebrates that provides an assessment of river or ecosystem 'health'.

    The indicator provides a quantitative assessment of river health based on AusRivAS scores. For the purposes of this assessment, river health is usually defined in terms of ecological integrity and is used to give a measure of the overall condition of a river ecosystem. The working definition of 'river health' is:

    the ability of the aquatic ecosystem to support and maintain key ecological processes and a community of organisms with a species composition, diversity, and functional organisation as comparable as possible to that of undisturbed habitats within the region' (Schofield & Davies 1996).

    AusRivAS bioassessment is a group of standardised methods for assessing the ecological health of rivers based on biological monitoring and habitat assessments. To date, AusRivAS bioassessment consists of rapid, nationally standardised sampling and analysis protocols for one aquatic ecological component - macroinvertebrates. Aquatic macroinvertebrates are very diverse, are drawn from a range of insect, crustacean and molluscan groups, and include snails, water boatmen, dragonflies, stoneflies, mayflies and aquatic worms. They are highly useful indicators for biological monitoring, generally visible to the naked eye and found in all freshwater habitats. They are an important source of food for fish and platypus. They are widespread, easy to sample, relatively immobile, and most importantly, their composition reflects the aggregate of environmental changes impacting on the stream ecosystem for up to several months prior to sampling. Therefore they provide an 'integrated' indicator of human impact on the stream ecosystem.

    AusRivAS bioassessment is a set of sampling protocols and state-specific, predictive 'models' which use field data to predict the aquatic macroinvertebrate families that would be expected to be present at a test site if it were free from human impacts (in 'reference' condition). AusRivAS river health assessment scores are based on the ratio of the number of aquatic macroinvertebrate families found at test sites to the number predicted to occur there under undisturbed conditions. The predictions are derived from a large set of reference river sites with similar geographic and physical features. The AusRivAS computer models used to determine these scores have been developed using habitat information and macroinvertebrate surveys conducted at over 2000 carefully selected, minimally impaired reference sites.

    A national assessment of Australia's inland waters using the AusRivAS system has been undertaken through the National River Health Program's Australia-wide Assessment of River Health (AWARH) and funded through the Natural Heritage Trust. The results of this assessment are reported below (see Figure 26 to Figure 33 and Table 40). This data set represents the only nationally consistent and standardised freshwater biota data set currently available. It is also the only truly national biological data set (terrestrial or aquatic) that is benchmarked against undisturbed 'reference' conditions.

    Water quality and habitat changes can cause the loss of sensitive macroinvertebrate fauna. Consequently, a ratio of the observed number of macroinvertebrate families to the expected number of families (the O:E ratio or score) is calculated for each test site. The value of the O:E score can range from zero (indicating that none of the expected families was found at the site) to around one, with values close to one indicating that the site has a community composition similar to reference sites and is thus minimally disturbed. The AusRivAS O:E score provides a reliable, standardised and regionally relevant river health indicator that is responsive to a variety of impacts, including water quality degradation, habitat destruction, and altered flow regimes.

    The O:E scores are also assigned to categories or bands that describe different levels of biological condition, ranging from 'richer than reference' condition (containing more families than expected) to 'extremely impaired' (containing very few of the expected families). These bands can be used to provide a summary report of the overall condition and severity of impacts for various sites.

    River health condition scores generated by AusRivAS do not provide a definitive indication of the cause of a disturbance (although the detailed macroinvertebrate data can be used to do this). However, these river condition scores do enable the current condition of individual streams to be placed in a nation-wide context. From this, 'stressed' or priority rivers requiring further investigation and management action have been identified.

    The AWARH information was provided by the states and territories to the National Land and Water Resources Audit and for this national State of the Environment Report. The AusRivAS bioassessment data described here are derived from family-level macroinvertebrate bioassessments conducted at over 4599 'test' sites surveyed around Australia during the AWARH survey. The indicator as reported here is based on 3112 test sites and 1487 reference sites. These test sites were selected as being representative of river reaches of significant management concern in each state or territory. They were selected on advice from state agencies, local governments, industry, catchment organisations, and community groups. A principle aim of the AWARH survey was to provide assessments of direct relevance to local or regional river management issues. Data from these sites therefore form the basis, or benchmark, against which future assessments of the efficacy of river management activities across Australia will be measured. They do not, in consequence, form an unbiased sample of river reaches across Australia.

    The information depicted in Table 40 does not include reference sites, as their inclusion could unreasonably bias the results. Moreover, the point-based nature of the assessment data is not extrapolated to the entire river basin or drainage division at this stage. The survey data indicate that 5% of the sites assessed using AusRivAS were more biologically diverse than expected, while a further 55% had similar levels of biodiversity to minimally disturbed (reference) sites. Thirty-one per cent of sites were significantly impaired, 8% of sites were severely impaired and 1% of sites were found to be extremely impaired. In general terms, the interim indicator shows that approximately 60% of the assessed sites were either more biologically diverse or had similar biological diversity to the reference sites and were therefore likely to be in good ecological condition or 'health'. The indicator also shows that the remaining 40% of assessed sites have lost between 15 and 100% of macroinvertebrate taxa that would have occurred under undisturbed or natural conditions, and therefore have significantly to extremely impaired ecological health.

    Table 40: River sites assessed using AusRivAS macroinvertebrate bioassessment during the first Australia-wide Assessment
    of River Health (AWARH) survey (all states and territories 1994-1999)A
    Number of test sites Number of reference sites Total      
    3112 1487 4599      
    Number of sites per bandB, C
    X
    More biologically diverse than reference
    A
    Similar to reference condition
    B
    Significantly impaired
    C
    Severely impaired
    D
    Extremely impaired
    Total
    All test sites
    154
    1702
    963
    254
    39
    3112

    A Data as at 1 June 2000; analysis 9 April 2001.
    B Based on information provided by states and territories for the National Land and Water Resources Audit and national State of the Environment Reporting.
    C State data and information collated and analysed by the CRCFE (http://ausrivas.canberra.edu.au/ ).

    New South Wales (and Australian Capital Territory)

    Most river systems in New South Wales showed evidence of human pressures on macroinvertebrate communities. Only some of the smaller, less developed coastal river systems in the far south and mid-north of the state had macroinvertebrate communities that were not affected by human pressures. The two major river systems that include the Sydney metropolitan area had severely impaired communities; however, the test sites were not representative of the whole catchment. Despite this bias, the individual site information indicates that most waterways in highly urbanised areas have impoverished macroinvertebrate communities.

    Northern Territory

    In the Northern Territory data were only available for a few north-western river systems. Macroinvertebrate communities in these river systems showed no evidence of human pressures.

    Queensland

    Generally macroinvertebrate communities in the coastal basins of Queensland showed no evidence of human pressures except for a few small, more developed basins. Inland catchments generally showed some evidence of human impact with most river systems having significantly impaired macroinvertebrate communities except for the Diamantina River, Bulloo River and Paroo River.

    South Australia

    The 'health' of rivers was unable to be assessed in most South Australian catchments as many waterways are predominantly dry and ephemeral. In Willochra Creek, macroinvertebrate communities were severely affected by human activities. Other river systems with significantly impaired macroinvertebrate communities include Murray River basins, Diamantina River and Spencer Gulf.

    Tasmania

    In most rivers in Tasmania, the macroinvertebrate communities showed some evidence of human impacts with significant impairment the most common condition. The Pieman River was assessed as being severely impaired; however, this assessment could be biased as the test sites were affected by mining activities and did not provide a representative picture of the whole catchment.

    Victoria

    Macroinvertebrate communities of river systems in central Victoria showed some evidence of impact with most communities being significantly impaired. The less-developed river systems in the Gippsland region and in the far west of the state showed no evidence of human impact.

    Western Australia

    In most of the coastal rivers of Western Australia, macroinvertebrate communities have not been affected by human activities. River systems that showed evidence of impact (significantly impaired) include the Sandy Desert, Moore-Hill Rivers, Swan Coast, Blackwood River, Frankland River and the Avon River.

    Figure 26: Summary of AusRivAS bioassessment results for all river sites surveyed in New South Wales
    (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in New South Wales
    Legend for Figure 26

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 27: Summary of AusRivAS bioassessment results for all river sites surveyed in Victoria (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in Victoria

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 28: Summary of AusRivAS bioassessment results for all river sites surveyed in Queensland (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in Queensland

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 29: Summary of AusRivAS bioassessment results for all river sites surveyed in Western Australia (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in Western Australia

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 30: Summary of AusRivAS bioassessment results for all river sites surveyed in the Northern Territory (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in the Northern Territory.

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state or territory authority.

    Figure 31: Summary of AusRivAS bioassessment results for all river sites surveyed in Tasmania (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in Tasmania

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 32: Summary of AusRivAS bioassessment results for all river sites surveyed in South Australia (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in South Australia
     Summary of AusRivAS bioassessment results for all river sites surveyed in South Australia

    Note: O = observed number of types of animals, E = expected number of types of animals.

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state authority.

    Figure 33: Summary of AusRivAS bioassessment results for all river sites surveyed in the Australian Capital Territory (Numbers refer to AWRC basins.)

     Summary of AusRivAS bioassessment results for all river sites surveyed in the Australian Capital Territory

    Source: Co-operative Research Centre for Freshwater Ecology 2001, data supplied by relevant state or territory authority.

    Case study 13: Indigenous food sources - Barwon Wetlands

    For thousands of years Aboriginal people have lived very closely with the land. This special relationship has been passed down through laws, customs and stories. One area where Aboriginal people have had a strong connection with the land and water is the lower Barwon River, from Mugindi on the Queensland/New South Wales border to Brewarrina, including the Narran River and Narran Lakes. This region is part of the Darling Riverine Plains Bioregion. Four hundred species of terrestrial animals have been recorded in this region, including 47 mammals, 256 birds, 20 frogs and 77 reptiles. One hundred and seventy five plant species also occur in this area.

    The Aboriginal people who lived in the Barwon River Wetlands before European occupation followed a nomadic lifestyle. The wetlands provided a variety of food, including native fish and the many animals that came to drink at the waters edge. Important fish species of the wetland included bony bream, freshwater catfish, silver perch and golden perch.

    The Barwon River Wetlands contained the Ngunnhu fish traps at Brewarrina, developed thousands of years ago by Aboriginal people. These traps were designed to trap fish swimming in either direction.

    Other food sources of Aboriginal people included freshwater invertebrates, crabs, prawns, shrimp, yabbies and crayfish which were caught either by baited line or sorted from the mud of the wetlands. Additionally, plant species dependent on either the water or the seasonal flooding of the Barwon wetlands were collected and used for food or medicine.

    European settlement in the Barwon Wetlands reduced the level of food supply for the Aboriginal population. Of the 400 species in the region, 26 are now listed under NSW legislation as extinct, 43 as threatened and 95 are listed to be of conservation concern (IRN 2000).

    The initial impact of European settlement on Aboriginal people was the occupation of Aboriginal land by settlers, forcing Aboriginal people to land of poorer quality. Additionally, European practices of land clearing and cropping used a large amount of water and introduced pesticides and weeds into the surrounding environment. Stock and other introduced species competed with native animals for food and water, as well as competing with Aboriginal people for food. Of the 11 species that were common Aboriginal food sources, only three can still be found.

    River modifications have also affected the food supply of the Barwon Wetlands. The large fish traps were removed to allow paddle-steamer access and to provide construction materials for roads, buildings and dams. Fish habitats, such as snags, were removed to allow faster flow of rivers and downstream dams have prevented the migration of fish. Water extractions from the Barwon River have exceeded the cap placed on the river by the Murray-Darling Basin Commission (MDBC) in 1997/98. All these activities have had an impact on aquatic populations.

    European settlement around the Barwon Wetlands has reduced the potential of Aboriginal people to care for the land and use its resources. For future management it is recommended that local Aboriginal people be included in the decision-making processes for land issues in the area. Restoration of a healthy environment at the wetlands would again enable Aboriginal people to have access to clean water and traditional foods, and to be able to use the wetlands for cultural and spiritual activities.

    Messages on the condition of aquatic ecosystems
    • Riparian zone habitats are in poor condition in many areas due to the effects of grazing, land clearing, modified flow regimes, salinity and the spread of exotic species.
    • It is likely that many wetland habitats are currently decreasing in area mainly due to the effects of modified flow regimes, floodplain isolation and, increasingly, salinity. Eighty important wetlands are already affected by salinity and this will rise to 130 by 2050 (NLWRA 2001b).
    • Native fish populations in some river systems are under severe stress from barriers to fish movements, poor water quality, reduction in habitat and competition from exotic species. Six per cent of native fish species are considered threatened. Over the past 20 years some native fish species have disappeared from rivers in News South Wales. There are insufficient data from other states to assess changes in native fish populations.
    • Australia currently has 208 recognised frog species, 27 of which are considered threatened (20 endangered and 7 vulnerable). As in other parts of the world, there has been significant decline in frog populations in Australia. Loss of habitat, poor water quality, pesticides and disease have been proposed as reasons for the decline in numbers. The chytrid fungus has been implicated as a significant cause in the decrease of some frog populations in Australia.
    • Fifty per cent of Australia's inland waterbirds are listed as extinct, vulnerable or near threatened primarily due to wetland and riparian habitat loss.
    • Platypus and some species of freshwater crayfish are considered to be at risk primarily from loss of habitat; however, there is only limited information on the distribution and condition of these animals.
    • A national assessment of river 'health' was undertaken using the AusRivAS protocol which compares macroinvertebrate communities at a test site with an undisturbed reference site. At 31% of sites macroinvertebrate communities were significantly impaired, at 8% of sites they were severely impaired and at 1% of sites they were found to be extremely impaired. Declining river health as measured by AusRivAS is related to a range of stressors including catchment modification, water quality degradation, and flow regulation. Specific stressors affecting river health include urbanisation (as measured by catchment imperviousness), urban run-off, STP discharges, agricultural land use, mining discharges, forestry, nutrients and sediments, flow and impoundments. In highly developed states such as New South Wales, macroinvertebrate communities in most river systems displayed some degree of impairment, whereas in the less-developed river systems of Western Australia there was little or no impairment.
    Aerial view of a lake in the Snowy Mountains

    Aerial view of a lake in the Snowy Mountains
    Source: Environment Australia.