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3. Current status3.1 Introduction

This chapter presents an overview of the current status of hydrology, water quality, fish and waterbirds of the Lake Eyre Basin. Because of the highly variable nature of the Basin, as well as the general lack of long-term information, this chapter does not attempt to evaluate ecological condition based on historical records or reference sites. Rather, the information presented here provides a baseline from which future changes can be assessed within the context of natural variability or in relation to pressures and threats such as climate change. Additionally, findings are interpreted in relation to current ecological understanding and knowledge of environmental responses to human pressures to ascertain a general picture of the Basin’s current condition. Where relevant, this assessment is also informed by comparisons with neighbouring regions, particularly the MurrayDarling Basin. It should be noted that the previous assessment of the Basin’s condition produced in 2008 did not provide a quantitative baseline against which changes in condition might be assessed. In contrast, this 2016 assessment introduces a quantitative baseline for several key parameters.

3.1.1 Knowledge sources and approach

The information presented in this chapter was compiled from a wide range of sources (Table 1). Much of the information was sourced from the Lake Eyre Basin River’s assessment monitoring program. This monitoring program collected data on the fish communities, water levels and water quality at 53 waterholes across the Basin between 2011 and 2016 (Appendix 1; Figure 1). Surface water hydrology was also examined using available flow records from a selections of gauging stations located in the Cooper, Diamantina, Finke, Georgina, Macumba and Neales Rivers. Water quality was reviewed from state-based databases, quantitative analyses being limited to data on nutrient measurements. Waterbird status was informed by data collected under the Eastern Australian Waterbird Survey, which has monitored waterbird communities at 10 major wetlands in the Basin since 1983 (Kingsford et al. 2012). Knowledge from other published studies was also considered where relevant to the aquatic focus and the parameters selected for condition assessment (Table 1).

Status assessments are made on the basis of expert evaluation of available data with respect to current scientific understanding. Each section in this chapter (hydrology, water quality, fish and waterbirds) takes a different approach to evaluating status, largely due to differences in data availability, type and quality. In most cases, the overall approach involves the assessment of patterns of key attributes in space and time and evaluation of these patterns in relation to climate, hydrology or human pressures. Particular attention has been given to ascertaining the existence of any longer-term trends, especially declines, in the status of these ecological components. For the Coongie Lakes Ramsar site, status is also considered in relation to the limits of acceptable change in ecological character set under the Ramsar Convention on Wetlands (DEWHA 2008; Butcher & Hale 2011).

Lake Eyre Basin State of the Basin Condition Assessment 2016 Report

3.1.2 Aboriginal engagement

Indigenous interests in relation to water are recognised under the National Water Initiative of 2004. The National Water Initiative sets out a number of agreed outcomes and commitments to specific actions that are captured under eight key elements. Indigenous interests in relation to water are covered under the key element ‘Water Access Entitlements and Planning Framework’. Each of the signature governments have agreed that, once initiated, their water access entitlements and planning frameworks will recognise Indigenous needs in relation to water access and management (clause 25 ix). There are three actions to support delivery of the outcome under the National Water Initiative, which are identified in clauses 52, 53 and 54.

The Lake Eyre Basin Intergovernmental Agreement requires appropriate representation of Aboriginal interests in the development and implementation of policies and strategies for the Basin. This is achieved through Aboriginal representation on the Lake Eyre Basin Community Advisory Committee, and by working with Lake Eyre Basin Indigenous Rangers on programs, and through Lake Eyre Basin Aboriginal Forums.

Aboriginal Forums are information-sharing events are open to all recognised Aboriginal representative bodies and individuals located within the Lake Eyre Basin. Aboriginal Forums have been held at Hamilton Downs in Alice Springs, Mount Serle in South Australia, Birdsville in Queensland and Tibooburra in New South Wales.

At the second Aboriginal Forum held at Mount Serle, South Australia, in 2006, participants agreed that a Lake Eyre Basin ‘Aboriginal Way’ Map would be produced to promote Aboriginal culture and heritage in the Lake Eyre Basin. An Aboriginal Map Steering Committee was established to assist the Australian government by providing advice and guidance to the Australian, state and territory governments in the finalisation of the Map, including cultural advice and assistance in the consultation process with Aboriginal communities throughout the Lake Eyre Basin. The Steering Committee consisted of Aboriginal representatives from the Lake Eyre Basin Community Advisory Committee, invited elders and archaeological and linguistic experts. The Map is expected to be released in late 2017.

The third Lake Eyre Basin Aboriginal Forum held in Birdsville, Queensland, in 2009 highlighted ‘the need for water planning processes in all Basin jurisdictions to engage Aboriginal people, including through Aboriginal and other community education and participation in the Lake Eyre Basin Rivers Assessment. In response, jurisdictions began a process of engagement supported by a review commissioned by Department of Environment, Water and Natural Resources to explore how the Lake Eyre Basin Rivers Assessment program could bring together scientific and culturally appropriate approaches to assessing the condition of rivers (Nursey-Bray 2015). This review highlighted the following points and conclusions.

Water is of paramount importance to Aboriginal people in the Basin, representing a composite of values that is socially and culturally significant. Aboriginal views are underpinned by the notion of ‘Country’, which reflects a seamless connection between people, land and waters. Water is not split up into different aquatic ecosystems or legal jurisdictions, as is the case in western classification, but understood as one resource with multiple sites within the Country. The idea of health here is important. Unlike western


classification systems, cultural and ecological indicators are not separated but woven together. For example, the finch (katyapara) is of particular significance to the Arabana people and features as a symbol in representations of their culture. For Arabana people, the presence of finches represented not just ecological but also cultural health of a water site (Nursey-Bray 2015).

The review further explored how the Lake Eyre Basin Rivers Assessment program could bring together scientific and cultural approaches and whether their integration through a 'one-model-fits-all' template was appropriate. Integration implies the incorporation of Indigenous knowledge into current jurisdictional and institutional arrangements, but they may simply not fit. The alternative notion of co-existence recognises that both parties are equal and that each knowledge system is legitimate. The outcomes of Nursey-Bray’s (2015) study suggested an appropriate model within which both cultural and scientific knowledge about the region can co-exist, without being subsumed one into the other. It proposed an approach by which cultural and scientific assessment approaches occur side-by-side, bringing the strengths of each to the process.

The jurisdictional officers from Northern Territory, Queensland and South Australia involved in the Lake Eyre Basin Rivers Assessment monitoring program have worked together with the Aboriginal communities in the following ways. In the Northern Territory, Central Land Council staff supported involvement of Tjuwanpa Rangers from the Western Arrernte people. In Queensland, Lake Eyre Basin Rangers of the Dugalunji Aboriginal Corporation participated in the monitoring program. In South Australia, the Arabana helped develop an appropriate engagement model, and the Adnyamathanha and the Aboriginal community of Oodnadatta participated in field education events about the Lake Eyre Basin Rivers Assessment program. At the Lake Eyre Basin Aboriginal Forum in Tibooburra New South Wales, 2011, a description of the Lake Eyre Basin Rivers Assessment program was presented in a question-and-answer session. Through these activities and events, productive discussions and an understanding of each other’s cultural domains were progressed and continue to be developed.

The conclusions of Nursey-Bray (2015) highlighted the following two dimensions required for further progress in Aboriginal engagement in monitoring and evaluation:

1. supporting Indigenous rangers to institute ongoing cultural monitoring on their country across their water sites

2. ensuring that such monitoring builds community capacity.

Image 5. Water quality sampling for the Lake Eyre Basin Rivers Assessment program. Photo: D McNeil


Table 1. Summary of major sources used to inform assessments of hydrology, water quality, fish and waterbirds for the Lake Eyre Basin State of the Basin Report 2016. Theme Data sources Spatial extent Temporal

extentKey references

Hydrology A review of Basin’s hydrology was prepared to inform this report and comprised a comprehensive examination of available data including Lake Eyre Basin Rivers Assessment monitoring data.

Basin-wide All available

Unpublished report^1 prepared by Justin Costelloe (Melbourne University).

Australian Water Availability project Basin-wide 20082015 http://www.csiro.au/awapState gauging stations Representative/available stations from

Cooper, Diamantina, Georgina, Finke, Macumba and Neales

20072015 https://water-m oni t o r in g. info rm a t ion .ql d .g ov . a u / ; htt p s ://n t.g ov . a u / e n vi r on m e n t / w a t e r / w a t e r - da t a - p o rt a l ; htt p s :// www.w a t e rc onn e ct.s a . g ov . au Refer to Appendix 1: Table 1 and Figure 1 for location details of gauging stations

Longer-term trends

State gauging station Cullyamurra, Cooper Creek 19732015 htt p s :// www.w a t e rc onn e ct.s a . g ov . au

Groundwater interactions

High Ecological Value Aquatic Ecosystems sub-project MidFinke waterholes Duguid 2013

Published study Neales 20112015 Costelloe et al. 2005Waterhole hydrology

Lake Eyre Basin Rivers Assessment program 53 waterholes across Basin (see Figure 1) 20112015 Cockayne et al. 2012; Cockayne et al. 2013; Duguid et al. 2016; Mathwin 2015; Schmarr et al. 2017; Sternberg et al. 2014

Queensland waterhole modellingPublished studies

Water quality*

Basin water quality review to inform this report involved quantitative analysis of nutrient and associated data for South Australia and Queensland, analysis of Lake Eyre Basin Rivers Assessment data for Northern Territory, and consideration of summary findings from annual monitoring reports. Analysis was not comprehensive due to resource and data limitations

Basin wide Northern Territory records(2011 2016)plus see below

No integrated report produced, multiple contributors ^2.

State datasets (from gauging stations); only datasets including nutrient data used

Multiple sites in Cooper, GeorginaDiamantina catchments

1970s2015

https://wetlandinfo.ehp.qld.gov.au/wetlands/assessment/monitoring/current-and-future-monitoring/ Refer to Appendix 1: Tables 2, 3 and 4 for a summary of water quality statistics

Monitoring River Health Initiative; Australian Rivers Assessment Program

Multiple sites in Cooper, GeorginaDiamantina catchments

19941999 http://pandora.nla.gov.au/tep/25389

Lake Eyre Basin State of the Basin Condition Assessment 2016 Report 4

http://pandora.nla.gov.au/tep/25389

https://wetlandinfo.ehp.qld.gov.au/wetlands/assessment/monitoring/current-and-future-monitoring/



https://www.waterconnect.sa.gov.au/

https://www.waterconnect.sa.gov.au/

https://nt.gov.au/environment/water/water-data-portal



https://water-monitoring.information.qld.gov.au/

http://www.csiro.au/awap

Theme Data sources Spatial extent Temporal extent

Key references

Water quality*

Aquatic Ecosystem Condition Report (SA Arid Lands) Multiple sites in Cooper, GeorginaDiamantina, Neales and Macumba

2012 http://www.epa.sa.gov.au/data_and_publications/water_quality_monitoring

Published studies Cooper 20012004 Sheldon & Fellows 2010GeorginaDiamantina Williams et al. 2015

Diatom study 17 sites in Cooper and Diamantina (Queensland)

20142015 J. Tibby (unpublished data); J.Tibby and P.Goonan (unpublished analysis)

Fish A review of Basin fish ecology and condition was prepared to inform this report and comprised a comprehensive examination of available data including Lake Eyre Basin Rivers Assessment monitoring data.

Basin-wide All available

Unpublished report^3 prepared by Schmarr et al.

Lake Eyre Basin Rivers Assessment monitoring data Cooper, GeorginaDiamantina, Finke, Macumba and Neales catchments

20112016 Cockayne et al. 2012; Cockayne et al. 2013; Duguid et al. 2016; Mathwin et al. 2015; Sternberg et al. 2014

Waterbirds A review of the Basin’s waterbird monitoring data was prepared to inform this report.

Eastern Lake Eyre Basin major wetlands(Eastern Aerial Waterbird Survey)

19832016 Unpublished report^ 4prepared by Kingsford and Bino (University of New South Wales)

Eastern Aerial Waterbird Survey Cooper wetlands—Lower Cooper, Lake Dunn, Lake Galilee, Lake Hope, Lake Yamma Yamma, GeorginaDiamantina —Goyders Lagoon, Lake Katherine, Lake Mumberry, Lake Phillippi, Lake Torquinnie

19832016 Kingsford et al. 2013, Kingsford et al. 2016

Coongie Lakes survey Innamincka Regional reserve 2008 Kingsford et al. 2012^ Material from the unpublished reports prepared for the 2016 condition assessment (the reports on hydrology, fish and waterbirds) are included in this report but instances are not individually referenced; all other sources are cited in the standard way.

* N.B. Water quality data were also collected under the Lake Eyre Basin Rivers Assessment program but were not compiled for the quantitative analyses discussed here; however, they were used to inform the assessment. Water quality data from the Lake Eyre Basin Rivers Assessment are available from this program’s annual reports (Cockayne et al. 2012; Cockayne et al. 2013; Sternberg et al. 2014; Mathwin et al. 2015; Duguid et al. 2016; Schmarr et al. 2017).1. Assessment of hydrological status was conducted by Justin Costelloe, University of Melbourne.2. Assessment of water quality status was conducted by Peter Goonan and Tracey Corbin (South Australia Environment Protection Authority), Angus Duguid and Simon Townsend (Northern Territory Department of Environment and Natural Resources), John Tibby (University of Adelaide) and Bernie Cockayne (Queensland Department of Natural Resources and Mines).3. Assessment of fish community status was conducted by David Schmarr, Rupert Mathwin and David Cheshire (South Australian Research and Development Institute), Angela Arthington (Griffith University), Angus Duguid (Northern Territory Department of Environment and Natural Resources) and Bernie Cockayne and David Sternberg (Queensland Department of Natural Resources and Mines).4. Assessment of waterbird status was conducted by Richard Kingsford and Gilad Bino (University of New South Wales).


http://www.epa.sa.gov.au/data_and_publications/water_quality_monitoring

http://www.epa.sa.gov.au/data_and_publications/water_quality_monitoring

3.2 Hydrology

3.2.1 Key messages

Rivers in the Lake Eyre Basin are among the most hydrologically variable in the world and are, on average, about twice as variable as those from other arid zones. The key aspects of the Basin’s hydrology summarised below are vital context for other aspects of river condition.

• Hydrology of the Basin between 2008 and 2016 was shaped by two contrasting periods: a mostly wet period between 2009 and 2012 and a predominantly dry period from 2012 to 2015. Wetter conditions returned to much of the Basin in 2016, and earlier (January 2015) in Georgina, Macumba, Finke and Warburton.

• Streamflow records are too short and too variable to detect any long-term changes in surface water hydrology; however, given the current relatively low level of water resource development, for much of the Basin the surface water flow regime is considered to be near natural condition.

• Interactions between surface and ground waters remain poorly understood. Evidence suggests that groundwater is likely to make important contributions to the hydrology of some Basin waterholes. Streamflow is also likely to be an important source of recharge for both deep (Great Artesian Basin) and shallow ground waters, which are ecologically significant because they sustain spring ecosystems and riparian trees respectively.

• Considerable advances have been made in monitoring hydrology through the Lake Eyre Basin Rivers Assessment monitoring program. The knowledge gained builds on studies (such as ARIDFLO) in understanding waterhole hydrology. Relationships between maximum depth at cease-to-flow and persistence, and between surface area and volume, have been identified. They enable patterns of aquatic habitat availability to be more accurately mapped in space and time.

• None of the limits of acceptable change for hydrology of the Coongie Lakes Ramsar site were breached between 2011 and 2016, although one was approached during the recent period of low flows in the lower Cooper.

3.2.2 Recent surface water patterns

Surface water hydrology in much of the Lake Eyre Basin between 2008 and 2016 was dominated by two contrasting climatic periods:

• predominantly wet conditions associated with a large La Niña episode between 2009 and 2012

• predominantly dry conditions from 2012 to 2015 resulting in drought across much of the Basin (Figures 5 and 6).

The wet period between 2009 and 2012 encompassed several large flood events including, in 2010, the third largest flood on record at Cullyamurra on Cooper Creek (Figure 7). Large floods were also experienced in many Basin catchments in 2011. In some of the western catchments and in the upper reaches of some eastern catchments, the 2011 floods were larger than those experienced in 2010. The 20102012 wet


period (which started as early as 2009 in some of the north-western catchments, e.g. Georgina) resulted in long periods of hydrologic connection between the upper and lower reaches of catchments as well as extensive floodplain inundation. At Cullyamurra on the lower Cooper Creek, for example, continuous flow occurred between 2010 and 2011, which is the longest continuous flow period on record. Significant connectivity also occurred between catchments during this wet period with the Georgina River flowing into the Diamantina. The Georgina River only occasionally flows into the Diamantina and, in this report, it is sometimes treated as a sub-catchment of the DiamantinaWarburton system, while in some contexts information on values and condition are presented separately for the Georgina. Similarly, the Macumba River joins the DiamantinaWarburton system before it reaches Kati Thanda–Lake Eyre; however, the Macumba sub-catchment is mostly treated as distinct in this report. During the wet period of 20092011, most or all of the major rivers that can flow to Kati Thanda–Lake Eyre did flow in, including the Cooper, the Neales and WarburtonDiamantina.

Following 2011, conditions rapidly dried and much of the Basin experienced drought conditions throughout the 20132015 period, with only small annual flows occurring in the lower reaches of the major rivers (Figures 5 and 6). The longest periods of no flow on record were observed during this time in the upper Cooper (Thomson and Barcoo rivers) and the western catchments (Finke, Macumba and Neales rivers). In the Neales River, two years without any streamflow were recorded while three years without flow were observed in the lower Finke. Many aquatic habitats in the western catchments dried out as a result, other than those fed by Great Artesian Basin springs. For example, Algebuckina Waterhole was the only riverine waterhole in the Neales catchment that retained water during this period, but even it reached critically low levels. In the upper and mid reaches of the Finke River, periods of low flow of two years or less were recorded in some locations, but many waterholes still persisted. Partial alleviation of the 2013-2015 drought occurred in 2014 and 2015, with some rainfall and streamflow in the northern and north-western catchments (Georgina) and flooding in the Macumba in 2015. A return to wetter conditions has continued into 2016 with floods occurring in most Basin catchments.


Image 6. Data logger used in waterhole sampling for the Lake Eyre Basin Rivers Assessment program. Photo: B Cockayne

Figure 5. Total rainfall across the Lake Eyre Basin in each 'water year' (1 October to 30 September) from 2008 to 2015. Mean annual rainfall across the Basin is also shown, illustrating that 2010 and 2011 were wetter than average while 2008 and 20132014 were drier than average. Source: Australian Water Availability project, Bureau of Meteorology (www.csiro.au/awap).



Figure 6. Hydrographs at representative gauging stations of upper and lower reaches of major Lake Eyre Basin streams (Cooper, Diamantina and Georgina rivers) and from available stations on the Finke, Macumba and Neales rivers. Only data on water level, rather than discharge, are available for the Macumba and Neales. Where gauging stations have sufficiently long records, the annual recurrence interval of each flood year is also shown on the hydrograph by numbers above bars. Grey dots represent Lake Eyre Basin Rivers Assessment sampling dates.

3.2.3 Longer-term surface water trends

The length of recorded data at most gauging stations in the Lake Eyre Basin is short relative to the inter-annual variation that occurs. This, and gaps in the recorded data from some stations, limit the identification of long-term changes in river flows (refer to Appendix 1 for location of gauging stations). The gauging station at Cullyamurra on Cooper Creek has been operating for a relatively long time (since 1973) and this 43-year record demonstrates the very high variability typical of Basin rivers (Figure 7). The hydrograph at this gauging station is dominated by large flood events and does not exhibit any significant trend in annual streamflow over time. Nor can hydrologic models be used to identify long-term changes in runoff and streamflow in the Basin for similar reasons, i.e. insufficient duration of records for model calibration and high levels of uncertainty in model outputs.

Figure 7. Hydrograph of Cooper Creek at Cullyamurra gauging station showing daily discharge in megalitres per day between 1973 and 2015.


Image 7. Cullyamurra waterhole in June 2013. Photo: S Colville

3.2.4 Groundwater interactions

Interactions between surface and ground waters in the Lake Eyre Basin are poorly understood. There is little evidence that groundwater discharge sustains river flows in the Basin except in a few reaches and in particularly wet periods. In the Finke River periods of persistent flow have been documented along long sections, especially in the wet periods of 20002001 and 20102011, which may have been sustained by elevated watertables (Duguid 2013). Groundwater discharge is most likely to contribute to streamflow in the upper reaches of catchments, although saline groundwater discharge has been observed following large flood events in the mid reaches of the Neales catchment (Costelloe et al. 2005) and in the Warburton section of the Diamantina system.

Groundwater discharge also contributes to sustaining water levels in some waterholes in the Basin. In the lower reaches and western catchments, groundwater discharge is typically saline. Consequently, waterholes affected by groundwater discharge often reach hypersaline levels within six to 12 months after flow ceases (Costelloe & Russell 2014). In Queensland, modelling has been conducted on 17 waterholes using observed water level data and modelled evaporation rates (Sternberg et al. 2014; B. Cockayne, unpublished data). Results suggest that none of these waterholes has any significant groundwater inputs but they do contribute to recharging of the unconfined groundwater table. Some deep waterholes, such as Cullyamurra and Nappa Merrie on the Cooper, have depths reaching 11 to 25 metres and are therefore highly likely to intersect the water table. Similarly, one waterhole in the mid-Finke is 11 metres deep when full (Duguid 2013). The extent of groundwater exchange in these important freshwater habitats has not been quantified.


Streamflow in the Basin contributes to the Great Artesian Basin. Recharge to the Great Artesian Basin from the lower reaches of the Finke River is likely to be particularly important as it contributes substantial volumes to the flow path that discharges into the Dalhousie Springs complex (Fulton 2012). Even small rates of recharge to local alluvial aquifers are critical to maintaining sufficient fresh groundwater to sustain riparian trees, as observed in the Cooper, Diamantina and Neales catchments (Cendón et al. 2010; Costelloe et al. 2008).

3.2.5 Waterhole hydrology

Significant advances have been made since 2008 in understanding the physical and hydrologic character of waterholes in the Lake Eyre Basin, especially in the Neales, Cooper and Diamantina in South Australia, the Thomson River in Queensland and the Finke River in the Northern Territory (Figure 8). Detailed information is now available on the location of many waterholes in these rivers, and much more is now known about factors controlling hydrologic persistence, such as maximum depth at cease-to-flow, frequency of inflows and groundwater connectivity. This knowledge is important for understanding the distribution, quality and persistence of aquatic habitat and significant refuges for aquatic fauna such as fish.

Studies of waterhole bathymetry and hydrology in some Queensland and South Australian waterholes indicate that maximum depth at cease-to-flow provides a reasonable indicator of how long waterholes are likely to persist in the absence of surface inflows (Costelloe & Russell 2014; Costelloe et al. 2007). A strong relationship between surface area and volume, but not surface area and persistence, has also been identified among some Queensland waterholes, allowing waterhole volumes to be estimated from satellite imagery.

Deep waterholes (i.e. greater than 6.6 metres deep and capable of persisting over three years without surface inflow) are absent from most of the western Basin catchments other than the Finke (Figure 8). In the Neales catchment, for example, Algebuckina waterhole is the deepest and most persistent waterhole and is a critical refuge for larger bodied fish that cannot persist in shallow Great Artesian Basin springs. By the end of 2014, it was the only waterhole retaining water in this catchment and nearly dried out following two years without streamflow.

Cullyamurra Waterhole on the lower Cooper is the largest and deepest waterhole in the Basin with a maximum measured depth of around 23.2 metres. The reach of the Cooper containing Cullyamurra (from around Nappa Merrie Waterhole to the junction of the Main Branch and Northwest Branch) also has the highest density of deeper waterholes in the Basin. These deep waterholes (greater than 4.4 metres at cease-to-flow) also have consistently good water quality and are considered to be significant long-term refuges for fish.


Figure 8. Distribution of waterholes in the Lake Eyre Basin with measured cease-to-flow depths (CTFD) in metres. Waterholes with cease-to-flow depths of 2.24.4 m can persist for more than one year without flow; those with cease-to-flow depths of 4.46.6 m for two years without flow; and those with cease-to-flow depths greater than 6.6 m for more than three years without flow.

3.2.6 Coongie Lakes

Under the Ramsar Convention of Internationally Significant Wetlands, limits of acceptable change have been defined for hydrological changes in the northwest branch of Cooper Creek that feeds the Coongie Lakes in South Australia (Table 3; Butcher & Hale 2011). These have not been triggered. However, the low flows in the lower Cooper over the past four years have approached one limit of acceptable change relating to Lake Goyder (Table 2). It is difficult to assess the two limits of acceptable change relating to waterhole persistence (numbers 4 and 5 in Table 2) because conditions in these waterholes are not effectively monitored by the Landsat record and do not have specific monitoring sites to measure water level variations.


Table 2. Assessment of hydrological limits of acceptable change for the Coongie Lakes Ramsar area (Butcher & Hale 2011).

Limits of acceptable change Status Evidence

1. Coongie Lake receives inflows no less than eight times in any ten-year period, with no dry period lasting longer than 12 consecutive months

Within Coongie Lake has received inflow in every year of the Cullyamurra record (1973-2016). The smallest annual flow through Cullyamurra, measured in gigalitres total, was in 1985. Modelling and Landsat data indicate that a small amount of inflow occurred to Coongie at this time (Costelloe et al. 2004). Logger data at Kudriemitchie show that Coongie has received inflow during the low flow years of 20132015.

2. Lake Goyder receives inflows no less than six times in any ten-year period, with no dry period lasting longer than 30 consecutive months

Nearly exceeded

Lake Goyder did not receive inflow in the 20132016 period according to the Landsat record, although some minor flows may have occurred that could not be detected. This is the longest dry period in the Cullyamurra record for this lake and it has been dry since December 2013 (30 months). However, the Lake has received inflow in six of the last ten years.

3. Large flood events occur no less than four times in any 30-year period (as defined by Costelloe 2008)

Within The Cullyamurra record shows that large flood events (more than 38 gigalitres per day) known to cause outflow from the Coongie Lakes system have occurred 1011 times in the past 43 years and 67 times in the past 30 years.

4. No drying of any permanent waterholes

Within Permanent waterholes are classified as those that typically receive inflow annually and have cease-to-flow maximum depths of greater than 4 m. These are restricted to Cooper Creek (Cullyamurra to Marpoo) and the Northwest Branch distributary (Scrubby Camp, Kudriemitchie). Embarka Waterhole on the Main Branch is also in this category as it is the only deep waterhole (cease-to-flow depth of 3.8 m) that receives annual inflow on the Main Branch.

Given that Coongie Lake received flow in every year of the Cullyamurra record, there has been no drying of permanent waterholes on Cooper Creek or the Northwest Branch. Embarka Waterhole requires approximately 1500 megalitres/day at Cullyamurra for inflow and there have been at least two years in the record where this was not received (1982, 1985) but the no flow period of 1418 months would not have resulted in the drying of this waterhole.

5. No drying of semi-permanent waterholes to less than 70% of time inundated over any 20-year time period

Not known This limit of acceptable change is difficult to assess without particular semi-permanent waterholes being identified with a known maximum cease-to-flow depth and long-term frequency of inundation. Semi-permanent waterholes on the Northwest Branch (i.e. in the connecting channels of the lakes) could be nominated, as could some of the deeper waterholes on the Main Branch downstream of Embarka Swamp (e.g. Narie, Cuttapirie Corner, Parachirrinna). Large downstream lakes, such as Lakes Hope, Killamperpunna and Killalpaninna, would be unlikely to meet this limit of acceptable change.


3.3 Water quality

3.3.1 Key messages

• No major deterioration of water quality has been observed in the Lake Eyre Basin since the 2008 assessment. Water quality is strongly influenced by preceding river flow history, evaporation and groundwater connection.

• The conductivity (i.e. salinity), turbidity and nutrient levels of the Lake Eyre Basin’s rivers are highly variable, both temporally and spatially. Most waters are alkaline, and dominated by bicarbonate and sodium ions.

• Streams of the northern and eastern Lake Eyre Basin (the Cooper and GeorginaDiamantina) tend to be mostly fresh, slightly alkaline and high in nutrients. Waterholes in the lower reaches of these catchments tend to be less turbid and become more saline between flows.

• In some parts of the Basin, nutrient concentrations and turbidity could be higher than natural levels. The high turbidity values are considered to be a natural effect of clay rich soils, whereas the process influencing nutrient levels are less well understood and need further research. High salinity in some parts of the Basin is a natural result of the arid climate.

• Existing national water quality guidelines are unsuitable for evaluating water quality in the Lake Eyre Basin due to the variable river conditions. Levels of nutrients and turbidity are often higher than the guidelines and appear to be naturally higher than in many Australian rivers. New guidance is currently under development for Australia’s temporary waters.

3.3.2 Overview

The Lake Eyre Basin Rivers Assessment program monitored the water quality of over 53 sites from 2011 in spring and autumn every year. Water quality is strongly influenced by patterns of flooding and drying and is therefore highly variable in both time and space (Sheldon & Fellows 2010). Water quality sampling in the Basin most often occurs at the persistent waterholes when rivers and streams are not flowing; however, some samples are from flowing conditions and the varied sampling times contribute to the high variability in some water quality parameters. The high levels of variability present a challenge for establishing threshold levels for acceptable water quality. Distinguishing the prevailing conditions for sampling records and incorporating this aspect into analysis is a challenge for determining water quality patterns and their causes.

Default stressor trigger values listed in the national water quality guidelines (ANZECC & ARMCANZ 2000) tend to be unsuitable for the arid, temporary rivers of the Lake Eyre Basin (Choy et al. 2002; Sheldon & Fellows 2010). Many Basin watercourses, for example, exhibit higher turbidity and nutrient concentrations than most other streams in Australia and New Zealand (ANZECC & ARMCANZ 2000) and also exceed those of arid streams in the United States (Evans-White et al. 2013). Similarly, limited trace element data available for the Basin indicate that the soluble copper, soluble zinc and aluminium concentrations in many sites have often been above the 90 per cent species protection toxicant values listed in the national water quality guidelines (ANZECC & ARMCANZ 2000). These measurements probably reflect the natural composition of clays in the catchment rather than any widespread human source of contamination (Williams et al.


2015). New guidance is being developed as part of the revision of the national water quality guidelines to provide advice on assessing and managing water quality in temporary waters that is relevant to all aquatic ecosystems of arid and semi-arid zones. Available water quality data indicate some general patterns between catchments, as well as between and within some sub-catchments. A summary of the water quality statistics is in Appendix 1, and Tables 2, 3 and 4.

Rivers and creeks in the eastern and northern rivers are mostly fresh (i.e. less than 500 micro-Siemens per centimetre conductivity), turbid (100500 nephelometric turbidity units) with high suspended solids (greater than 100mg/L), slightly alkaline (pH greater than seven) and tend to be dominated by bicarbonate and sodium ions and high nitrogen (greater than one milligram per litre) and phosphorus (greater than 0.1 milligram per litre; Table 3). Within the Diamantina catchment, nutrient concentrations increase downstream along the main channel with higher phosphorus concentrations detected in the Warburton River in the lower section of the Diamantina system (Table 5). Colour, an indirect measure of dissolved humic acids and tannins, is variable among rivers but low overall.

In the Cooper catchment, Torrens Creek exhibits notably high concentrations of nitrogen and also greater turbidity than the remaining catchment (Table 3). The source of nutrients over such a large spatial area is unknown but typical values recorded for most streams in the Basin are higher than those listed for desert streams elsewhere (Smith et al. 2003; Evans-White et al. 2013), contrasting with predictions of low nutrient levels for desert streams (Dodds et al. 2015). All but one site monitored exceeded the turbidity trigger of 100 nephelometric turbidity units, with 42 per cent of the sites exceeding the nitrogen trigger value of 1 milligrams per litre and 79 per cent of sites exceeding the phosphorus trigger value of 0.1 milligrams per litre.

Conductivity and salinity tend to be higher in the western rivers of South Australia and the Warburton River than in the eastern and northern rivers (Table 3), and are attributable to groundwater sources of salt. In the Finke River, salinity is particularly variable. Freshwater pools predominate in the upper parts of the catchment, whereas in the middle reaches waterholes exhibit a wide range of salinities even after accounting for time since flow, suggesting more complex interactions between surface and ground waters than in other Basin rivers (Duguid et al. 2016; Duguid & Hodgens unpublished data).

3.3.3 Temporal trends

Temporal patterns in available water quality data are highly variable across the Basin. No clear temporal trends in water quality are apparent even in the relatively long-term datasets from the Cooper and GeorginaDiamantina catchments, some of which extend back to the 1970s. In Cullyamurra Waterhole in the Cooper Creek, for example, changes in salinity and nutrients have fluctuated considerably since 1973, probably in relation to hydrologic conditions (Figure 9).

Pronounced short-term patterns in salinity have been observed in some waterholes, especially in the Finke, Neales and Diamantina Rivers, and are attributable to a combination of evaporation and groundwater discharge (A. Duguid, pers. comm.). Changes at individual sites are also strongly influenced by flow patterns. At some sites, especially in the Finke River (Duguid 2013), large flows appear to increase the influence of relatively fresh alluvial aquifers, offsetting temporarily the effects of more saline groundwater sources on waterholes following flows. The opposite pattern is observed in


the Neales and Diamantina, where large floods raise the unconfined saline groundwater table and result in high salinity discharge into the channel during low flows of the flood recession (Costelloe et al. 2005). In the typically low salinity waters of the mid and upper Cooper, Diamantina and Georgina catchments, patterns of increased salinity (although still low overall) have also been recorded between flows (Duguid et al. 2016; Mathwin et al. 2015; Sternberg et al. 2014).

Figure 9. Salinity (top) and major nutrients (bottom) recorded in Cullyamurra Waterhole in the lower Cooper catchment between 1973 and 2007.


Table 3. Water quality for some catchments of the Lake Eyre Basin. Mean values ± standard deviations—except pH, which is the median followed by the 10th and 90th percentiles in parentheses. N/A = data not available. Further details at Appendix 1.

Catchment Subcatchment Electrical conductivity

(µS/cm @25°C)

Salinity (mg/L)

pH Turbidity (nephelometric turbidity unit)

Total suspended

solids (mg/L)

Colour (Hazen

unit)

Total nitrogen (mg/L)

Total phosphorus

(mg/L)

Cooper Creek

Catchment (eastern

catchment)

Torrens Creek 219 ± 128 138 ±53 7.1 (6.8–7.4) 959 ±748 163 ±96 77 ±46 2.8 ±1.37 0.58 ±0.30Thomson River 175 ± 156 112 ± 82 7.3 (6.8–7.9) 528 ± 588 268 ± 343 45 ± 58 0.87 ± 0.57 0.25 ± 0.15Barcoo River 327 ± 283 206 ± 171 7.5 (7.0–8.5) 275 ± 460 255 ± 478 36 ± 31 0.85 ± 0.38 0.26 ± 0.25Cooper Creek (QLD)

214 ± 122 133 ± 69 7.5 (7.1–7.8) 549 ± 468 221 ± 269 17 ± 15 1.87 ± 1.59 0.47 ± 0.39

Cooper Creek (SA) 228 ± 176 124 ± 100 7.6 (7.2–8.1) 391 ± 243 67 ± 43 48 ± 37 1.31 ± 0.76 0.47 ± 0.40Georgina

Diamantina Catchments (northern

catchment)

Burke River 212 ± 109 123 ± 65 7.6 (7.4–7.9) 95 ± 60 102 ± 267 27 ± 27 0.55 ± 0.21 0.07 ± 0.04Georgina River 478 ± 497 301 ± 302 7.6 (7.0–7.8) 194 ± 201 81 ± 108 12 ± 11 0.85 ± 0.34 0.17 ± 0.11Diamantina River—Upper

190 ± 59 123 ± 35 7.7 (7.2–8.1) 423 ± 174 180 ± 133 10 ± 4 0.92 ± 0.55 0.29 ± 0.09

Diamantina River—Mid

127 ± 71 84 ± 37 7.4 (6.9–7.8) 689 ± 663 435 ± 440 36 ± 31 1.16 ± 0.79 0.44 ± 0.23

-Diamantina River—SA

262 ± 34 N/A 7.6 (7.4–8.0) N/A N/A N/A 1.84 ± 0.43 2.05 ± 0.35

Warburton Creek 1,024 ± 1,068 N/A 8.1 (7.8–8.3) N/A N/A N/A 1.12 ± 1.09 4.38 ± 1.31

Western catchments

(South Australia)

Macumba, Neales, Peake & Lindsay Rivers

6,250 ± 17,532N/A N/A NA N/A N/A 1.68 ± 0.67 0.1 ± 0.06

Finke River Low salinity waterholes

1,610 ± 1,350 N/A 7.9 76 ± 59 N/A N/A N/A N/A

High salinity waterholes

11,360 ± 12,030 N/A 8.0 24 ±23 N/A N/A N/A N/A


3.3.4 Biological indicators

Diatoms are a class of aquatic algae that tend to respond strongly to water quality. They are an important part of many aquatic food webs and have been used extensively as an indicator of water quality in Australia and around the world. The composition of diatoms in rivers is usually influenced by salinity, pH and nutrient status (Sonneman et al. 2000).

A total of 196 diatom taxa were identified from 17 Queensland waterholes in the Lake Eyre Basin in a study linking diatoms to water quality (J. Tibby unpublished data; J. Tibby & P. Goonan unpublished analysis). Diatom communities were characterised by taxa with a high nutrient tolerance. Of the five most abundant taxa, three (Luticola goeppertiana, Gomphonema parvulum and Nitzschia palea) have nutrient preferences that include the most nutrient-enriched category of streams in south-eastern Australia (Sonneman et al. 2000). Other abundant taxa (Navicula schroeterii and Gomphonema parvulum) have lower, but wide ranging, nutrient preferences.

A relationship between the composition of diatom communities and nutrients was identified, with some taxa more abundant at sites with lower nutrient levels and other taxa more abundant in higher nutrient sites. Total phosphorus explained the largest amount of variation in diatom communities with magnesium the only other influential water quality variable. Relationships between diatoms and pH and salinity are generally stronger than those found with respect to total phosphorus (Tibby 2004). At the 17 Queensland waterholes in the Basin, the reverse was found, reflecting the relatively narrow range of salinity values at those sites.

3.3.5 Condition

No major deterioration of water quality has been observed in the Basin since the 2008 assessment, yet in some parts of the Basin, nutrient concentrations and turbidity could be higher than natural levels. In the State of the Basin 2008: Rivers Assessment, Lake Eyre Basin catchments were assigned either a ‘good’ water quality condition or were not rated due to insufficient information. Expert review was required and locally derived reference sites were selected based on biological data, and included sites subject to dryland grazing but excluded sites influenced by other pressures and threats. Consequently, catchments were assigned ‘good’ water quality ratings despite recognition that nutrient levels were high at many sites (Lake Eyre Basin Scientific Advisory Panel 2009).

Water quality data and further information was available for the 2016 assessment, however the assessment is hampered by the naturally high variability of water quality and patchiness of the water quality data. Nutrients and turbidity levels in some of the Basin’s rivers are often higher than the water quality guidelines and appear to be naturally higher than many Australian rivers. The Basin’s high turbidity values are likely to be influenced by the natural effect of the clay-rich soils. Processes shaping nutrient concentrations in the Basin are less well understood, and although it is possible that the high nutrient levels at some sites are caused by human activity, further research is needed to gain a better understanding of these factors. The high salinity evident in some parts of the Basin is likely to be a natural feature of the arid landscapes drained by these rivers, driven by high evapotranspiration rates relative to low rainfall and infrequent streamflow, as well as the groundwater supply of salts to river pools. New guidance is currently under development for Australia’s temporary waters in recognition that the current water quality guidelines are unsuitable for hydrologically variable systems like the Lake Eyre Basin.


3.4 Fish

3.4.1 Key messages

• A large and extensive fish database has been created by the Lake Eyre Basin Rivers Assessment monitoring program, building on past work, including the ARIDFLO project (Costelloe et al. 2004) and the Dryland Rivers project (Bunn et al. 2006b). The result is substantially improved understanding of the distributions and population dynamics of fish species and the condition of fish communities.

• Fish communities are generally in good condition across the Basin, with riverine environments supporting 19 native fish species including the Lake Eyre yellowbelly and Barcoo grunter and three catfish species, including the endemic Cooper Creek tandan. Other endemic riverine fish species include Welch’s grunter, desert goby and Finke goby.

• Although fish communities in the Basin are generally in good condition, work conducted under the Lake Eyre Basin Rivers Assessment monitoring program has identified exotic and translocated species as a threat, including the risk of future translocations.

• Sleepy cod, an introduced species, has rapidly expanded its range in the Cooper Creek catchment between 2011 and 2016. Although this species is native to Australia it has been introduced to the Basin. The species was initially observed in the Thomson River and has expanded over six years downstream to Coongie Lakes in South Australia. Previous translocations of sleepy cod in Australia have resulted in rapid colonisation of the receiving environment, followed by a decline in species with similar niche requirements. It is currently unknown how this species will affect the native fish of the Cooper Creek catchment, particularly the Cooper catfish.

3.4.2 Fish distributions

Twenty native fish species have been recorded in the rivers of the Lake Eyre Basin Intergovernmental Agreement Area (Table 4). All the native riverine species were recorded under the Lake Eyre Basin Rivers Assessment monitoring program between 2011 and 2016, with the possible exception of one or two of the three carp gudgeon species which could not be distinguished in the field. A further nine native species are found exclusively within springs (Duguid et al. 2016); these were not monitored as part of Lake Eyre Basin Rivers Assessment monitoring program. (Additional information on this program is in Appendix 1.) The monitoring also recorded three species that have been introduced to the Basin. Two of these are non-Australian species (exotics) and the other is an Australian native translocated from other basins. Three more translocated species have been introduced to parts of the Basin, but may not have persisted. All six of these species that were introduced in recent decades are listed in Table 4. Some additional introduced species have been recorded in the past but do not persist (Duguid et al. 2016).

Given the aridity and limited drought refuges, this is an impressive number of native fish species, comparing well with the MurrayDarling Basin which has 33 native freshwater species (Lintermans 2009). The northern MurrayDarling Basin which, like the Lake Eyre


Basin, also has large sections of river that lack perennial base flow, is less arid and has only 21 native riverine species (Balcombe et al. 2011). Further details on species distributions within catchments and sub-catchments are provided in Duguid et al. (2016). The following paragraphs summarise the fish fauna characteristics of the main catchments monitored for the Lake Eyre Basin Rivers Assessment monitoring program.

In the Cooper Creek catchment 15 native riverine fish species have been recorded. In addition, five exotic or translocated species (Table 4) have been recorded, including reliable anecdotal reports of Murray cod and the release of MurrayDarling golden perch in the Cooper (David Sternberg, pers. comm.). However, these two species have not been recorded in six years of Lake Eyre Basin Rivers Assessment monitoring, suggesting limited distribution and abundance if they have persisted.

The GeorginaDiamantina catchment contains 13 native riverine fish species (Table 4). There are also unconfirmed records of translocated species being released in to the Georgina in the past: silver perch and MurrayDarling golden perch. They have not been recorded in six years of Lake Eyre Basin Rivers Assessment monitoring.

The Finke River has nine native species of fish and no extant, exotic or translocated species (Unmack 2001; Duguid et al. 2016); although European redfin were released in the 1950s they have not persisted (Duguid et al. 2005). The Finke River fish community is also of interest in that it contains three species endemic to that catchment (Finke goby, Finke hardyhead and Finke mogurnda), probably as a result of disconnection from the rest of the Basin (Table 4).

Eleven species of native riverine fish have been recorded in the Neales River, including one exotic species, gambusia. Four species in this catchment have only been observed occasionally (Welch’s grunter and Barcoo grunter) or in past surveys (silver tandan and Hyrtl's catfish, captured in ARIDFLO surveys in the early 2000s; Costelloe et al. 2004), but not during the Lake Eyre Basin Rivers Assessment program.

The Macumba River, with eleven native fish species, is the least studied of the Basin catchments and, until recently, only five species were recorded there (Cockayne et al. 2012). Another six species have now been observed in sites within the lower reaches, probably as a result of connectivity to the Diamantina River in 2011 and 2012 (Cockayne et al. 2012). In comparison to the Neales catchment, the assemblage of fishes that persist in the Macumba in drought years is less diverse, even though they each have 11 species recorded. The assemblages are similar, but each of the Neales and Macumba has one species recorded that the other does not.


Table 4. Distribution of riverine fish species in the Lake Eyre Basin (updated from Wager & Unmack 2000).

Family Genus Species Common name Cooper Georgina Diamantina Finke Macumba Neales

Clupeidae Nematalosa erebi bony herring ✓ ✓ ✓ ✓ ✓ ✓Retropinnidae Retropinna semoni Australian smelt ✓ - - - - -

Plotosidae

Neosiluroides cooperensis Cooper catfish^ ✓ - - - - -

Neosilurus hyrtlii Hyrtl's catfish ✓ ✓ ✓ ✓ ✓+ ✓Porochilus argenteus silver tandan ✓ ✓ ✓ - ✓ ✓

Atherinidae

Craterocephalus

centralis Finke hardyhead^ - - - ✓ - -

Craterocephalus

eyresii Lake Eyre hardyhead^✓ ✓ ✓

- ✓+ ✓

Melanotaeniidae

Melanotaenia splendida tatei

desert rainbowfish^✓ ✓ ✓ ✓ ✓ ✓

Ambassidae Ambassis sp. desert glassfish ✓ ✓ ✓ ✓ ✓+ -

Percichthyidae Macquaria ambigua MurrayDarling golden perch† † †? - - - -

Macquaria sp. Lake Eyre yellowbelly^ ✓ ✓ ✓ - ✓+ ✓Maccullochella peelii Murray cod* † - - - - -

Terapontidae

Amniataba percoides barred grunter - ✓ ✓ ✓ ✓+ ✓Bidyanus bidyanus silver perch† - †? - - - -

Bidyanus welchi Welch's grunter^ ✓ ✓ ✓ - ✓+ ✓+

Leiopotherapon unicolor spangled perch ✓ ✓ ✓ ✓ ✓ ✓Scortum barcoo Barcoo grunter ✓ ✓ ✓ - ✓+ ✓

Eleotridae

Hypseleotris klunzingeri Western carp gudgeon ✓ - - - - -

Hypseleotris sp.A Midgley’s carp gudgeon ✓Hypseleotris sp.B Lake’s carp gudgeon ✓Mogurnda larapintae Finke mogurnda^ - - - ✓ - -

Oxyeleotris lineolatus sleepy cod* † - - - - -

Gobiidae Chlamydogobius

eremius desert goby^ - - ✓ - - ✓

Chlamydogobius

japalpa Finke goby^ - - - ✓ - -


Family Genus Species Common name Cooper Georgina Diamantina Finke Macumba Neales

Glossogobius aureus golden goby - ✓ ✓ - - -

Poeciliidae Gambusia holbrooki Eastern gambusia† * - * - - *Cyprinidae Carassius auratus goldfish† * - - - - -

Total native species 15 13 14 9 10 11

Total translocated species 3 2

Total exotic species 2 1 1 0 0 1

✓ native to LEB – distribution in catchment; ^ endemic to the Lake Eyre Basin; * exotic to Australia; † translocated species (exotic to the Lake Eyre Basin); + first record by Lake Eyre Basin Rivers Assessment monitoring.

Note: three native riverine species are not listed above because they are only known from rivers that are not monitored under the Lake Eyre Intergovernmental Agreement (Frome River catchment and Bulloo catchment). They are listed in Duguid et al. (2016).

Note: silver perch have been translocated/released in the Frome River catchment in the Basin, as well as the possible release in the Georgina catchment.

Image 8. Hyrtl's tandan and barred grunter (at rear). Photo: M Rittner.


3.4.3 Endemicity and evolution

A high proportion of fish species in the Lake Eyre Basin are endemic (i.e. are unique to the Basin), according to current taxonomy and accounting for distinct but undescribed taxa. Of the 20 native riverine species of the main rivers, half are endemic (10 of 20; listed in Duguid et al. 2016) although one species (Barcoo grunter) did spread beyond the Basin for a few years in the floods of the mid-1970s. Three other riverine species are also endemic but occur in drainage lines of the Basin that are not in the Lake Eyre Basin Intergovernmental Agreement Area: false-spined catfish and Bulloo yellowbelly in the Bulloo catchment, and Flinders Ranges mogurnda in the Frome River catchment). Including all these species, the proportion of endemism in native riverine fish is 52 per cent (12 out of 23 species). The percentages are different if the Bulloo catchment is treated as a separate basin; however, the latest delineation of national surface drainage basin (in line with Geoscience Australia Geofabric) currently includes the Bulloo catchment as part of the Lake Eyre Basin.

A further nine fish species occur in the Basin but are restricted to Great Artesian Basin spring fed wetlands. All of these fish species are endemic to the Basin (note that two of the riverine species also occur in Great Artesian Basin springs and are not included in the nine that are restricted to springs). By combining the spring specialist and the riverine species the proportion of endemism in native fishes of the Basin is 56 per cent (18 of 32 species, if the Bulloo is treated as part of the Basin).

Despite the high endemism the Lake Eyre Basin shares many species in common with the neighbouring Barkly and Torrens river basins (Unmack 2001). Several other neighbouring regions also share some species with the Lake Eyre Basin, including the MurrayDarling Basin (nine common species), the Burdekin catchment (eight common species), the southern Gulf of Carpentaria (10 common species) and the western gulf of Carpentaria (nine common species) (Unmack 2001). Highly mobile species, such as spangled perch, can exhibit low genetic variation across these catchments, suggesting gene transfer through evolutionary and contemporary periods (e.g. Bostock et al. 2006).

Within the Basin, the Finke River has the highest level of endemicity to a particular river catchment, with three of its nine species unique to the Finke: Finke goby, Finke mogurnda and Finke hardyhead. Cooper Creek has one riverine species that is endemic to the Cooper catchment, the Cooper Creek catfish, while the GeorginaDiamantina, Neales and Macumba catchments have none. However, other Lake Eyre Basin endemics occur in multiple catchments: barcoo grunter, desert glassfish, desert goby, Lake Eyre yellowbelly, Lake Eyre hardyhead, and Welch’s grunter.

Recent genetic studies of Lake Eyre yellowbelly, desert rainbowfish, desert glassfish and desert goby indicate a complex history of riverine connectivity or isolation (Huey et al. 2011; Cockayne et al. 2013; Beheregaray & Attard 2015; Mossop et al. 2015). Studies of genetic variation in both Lake Eyre yellowbelly and desert rainbowfish, for example, show that populations in the Cooper are isolated from those in the Georgina, Diamantina, Macumba and Neales, suggesting a lack of contemporary connectivity via Kati Thanda–Lake Eyre among these catchments (Beheregaray & Attard 2015). Similarly, desert rainbowfish from the Finke River exhibit a large divergence from those elsewhere in the Basin, indicating long-term isolation of the Finke and a trend towards speciation in this catchment (Beheregaray & Attard 2015). Desert gobies also demonstrate genetic differentiation between Basin catchments, especially in the Finke. However, for a species with seemingly low dispersal ability, surprisingly high connectivity within catchments


is apparent in the desert goby (Mossop et al. 2015).

3.4.4 Exotic and translocated species

Fish monitoring over the last five years reveals the presence of two exotic and one translocated fish species in the Lake Eyre Basin. The two exotic species were introduced from the northern hemisphere (goldfish and gambusia). The other, sleepy cod, is a translocated species native to other Australian catchments but introduced to the Cooper Creek catchment.

Goldfish

Previous studies have listed goldfish as neither common nor widespread in the Basin (Arthington et al. 2005; Balcombe & Arthington 2009; Costello et al. 2010; Kerezsy 2010). It has been suggested that the naturally variable hydrological regimes of the unregulated Basin rivers afford some resistance to the establishment and proliferation of exotic fish (Costelloe et al. 2010). The lack of goldfish larvae and young juveniles detected during periods of large floods, for example, suggests that floods could potentially disrupt reproduction and recruitment of this species (Costelloe et al. 2010). However, comparatively high abundances of both adult and sub-adult goldfish were found throughout the Cooper, including the Thomson, Cooper and Barcoo systems, following the 20102011 wet season, with numbers subsequently diminishing rapidly in response to prolonged drought.

Monitoring revealed that goldfish recruitment is linked to flow conditions, with consecutive years of above average flows providing ideal conditions for population growth. In response to natural causes, notably the variable hydrological regime, goldfish are likely to return to lower numbers following such high recruitment. The abundance of sub-adult goldfish in the lower Cooper also suggests that the upper and mid Cooper may act as a source of goldfish for the lower catchment. Furthermore, goldfish distribution is likely to be controlled by waterhole persistence, with more goldfish occurring in areas where waterholes last for longer (i.e. upper and mid Cooper).

Gambusia

Gambusia is an exotic fish that can have detrimental effects on native fish through competition for resources and aggressive behaviour. Gambusia were recorded in low numbers in sites monitored by the Lake Eyre Basin Rivers Assessment (Cockayne et al. 2012; Sternberg et al. 2014; Mathwin et al. 2015; Duguid et al. 2016) and appear to have minimal impact on native species in most of the Basin’s riverine habitats (Costelloe et al. 2010).

Their persistence in riverine habitats, as well as large populations inhabiting uncontrolled artesian bores, presents a threat to native endemic fish of nearby spring habitats (e.g. the endangered red-finned blue-eye, Scaturiginichthys vermeilipinnis), which may infrequently be connected to riverine habitats (McNeil et al. 2011).

Gambusia is a restricted noxious fish under the Queensland Biosecurity Act 2014 and it is declared noxious under the South Australian Fisheries Management Act 2007. Gambusia was found in Alice Springs in 2000 and Darwin in 2014, but both populations were successfully eradicated.

Sleepy cod

Sleepy cod is a large, fish-eating gudgeon native to coastal drainages of north-eastern Australia and the Gulf of Carpentaria. When introduced to new habitats, this species can affect the abundance of small-bodied fish that are generalist predators, through both competition and direct predation. Consequently, sleepy cod is considered a conservation risk to native fish


species outside its natural range (Pusey et al. 2006).

Prior to 2008, sleepy cod were not recorded in the Basin. Current records indicate that this species has colonised many waterholes and ephemeral streams of Cooper Creek within a decade (Sternberg & Cockayne unpublished data). Fish size data, collected over six consecutive years (2011–2016) under the Lake Eyre Basin Rivers Assessment program, suggest a ‘colonising front’ of this species moving downstream with an origin in the vicinity of Longreach (Sternberg & Cockayne unpublished data).

3.4.5 Condition assessment

Biological Condition Assessment

The condition of fish communities in waterholes monitored under the Lake Eyre Basin Rivers Assessment monitoring program is evaluated here according to a conceptual framework known as the Biological Condition Gradient. This framework was initially developed in the United States to explain observed biological responses to stressors in aquatic ecosystems (Davies & Jackson 2006) and has since been adopted by the European Water Framework Directive, the South Australian Environment Protection Agency and the South Australian Research and Development Institute to be used in river condition assessment, including the Lake Eyre Basin Rivers Assessment program.

The Biological Condition Gradient framework provides an approach for evaluating the response of aquatic ecosystems to stress by considering how particular ecological attributes vary between tiers of increasing stress that range from a natural or unmodified state (Tier 1) to a severely altered state (Tier 6; Figure 10). For the Basin condition assessment, seven attributes were considered including various aspects of fish community structure. For a complete description of these attributes and how they vary between tiers, refer to Appendix 2.

To apply the Biological Condition Gradient framework in the Basin, fish data collected under the


Figure 10. Conceptual diagram illustrating the Biological Condition Gradient framework. The diagram shows the six tiers of decreasing biological condition in relation to a gradient of increasing stress.

Lake Eyre Basin Rivers Assessment program were used to divide catchments into ecoregions that represented reaches in which fish community dynamics exhibited similar patterns (Schmarr et al. 2015). Hydro-climatic phases were also delineated in time: dispersal phases, boom phases and bust phases (Schmarr et al. 2015). Specific attributes describing fish communities were then evaluated within the context of particular ecoregions and hydro-climatic phases to generate condition scores based on expected responses according to the six tiers of increasing stress and degradation (Table 5). More detailed information is provided in Appendix 2 regarding the rules used to determine Biological Condition Gradient scores for each attribute.

In evaluating condition scores, a score of 3 was adopted as a threshold of potential concern at a site scale (Table 5). Like limits of acceptable change, thresholds of potential concern are intended to alert managers to changes that may require a management response. Anomalies in particular attributes that might be overlooked at a site scale were also included in the Biological Condition Gradient rules developed for each site, and these attribute thresholds of potential concern were set at a tier score of 5 or 6 (Appendix 2).

Table 5. Fish community condition scores based on the Biological Condition Gradient framework.

Condition score Level of condition

1–2 Good

2–3 Acceptable

3–4* Poor

4–5* Very poor

5–6* Dire

*indicates scores beyond thresholds of potential concern at a site level.

Image 9. Fish sampling for the Lake Eyre Basin Rivers Assessment program. Photo: D McNeil.


Overall condition

Fish communities in sampled waterholes in the Lake Eyre Basin’s Agreement Area (refer to Figure 1) appear to be in good overall condition based on the assessment of Lake Eyre Basin Rivers Assessment monitoring program data collected between 2011 and 2016. Condition scores mostly ranged between 1 and 3 (i.e. good to acceptable; Table 5) and were, therefore, predominantly below the trigger value of 3, which would indicate a threshold of potential concern (Figure 11). Although streams in New South Wales were not monitored under the program, the New South Wales State of the Environment Report 2015 found the river condition of the Lake Frome region to be in very good health based on indexes for hydrology, fish, macroinvertebrates, riparian vegetation and physical form (New South Wales Environment Protection Authority 2015).

The matter of greatest disquiet regarding fish community condition is the expanding distribution and abundance of invasive fish species. Sleepy cod have spread from a source population in the vicinity of Longreach, becoming widespread and prolific in the Queensland portion of the Cooper catchment in less than a decade. They have also expanded into the South Australian portion of the Cooper Creek catchment between 2015 and 2016. The effects of sleepy cod on native fish populations and community condition are unlikely yet to be fully realised. Most other observed anomalies in the abundance and diversity of native fish detected during the Lake Eyre Basin Rivers Assessment monitoring are likely to reflect natural patterns of hydrological variability.

.


Figure 11. Average condition scores for fish communities in waterholes of each Lake Eyre Basin catchment sampled under the Lake Eyre Basin Rivers Assessment program between 2011 and 2016 (see Table 5). Dashed line indicates threshold of potential concern.

Cond

ition

Sco

re ra

ngin

g fr

om

good

(1-2

) to

dire

(5-6

)

Cooper Creek catchment

Four ecoregions were delineated in the Cooper Creek catchment: the upper Cooper, upper-mid Cooper, lower-mid Cooper and the lower Cooper (Figure 12). Fish communities were found to be in good (scores 1–2) to acceptable condition (scores 23) over the sampling period (Figures 11 and 12; Appendix 3). The upper-mid Cooper scored the highest condition while the upper Cooper, lower-mid Cooper and lower Cooper ecoregions were all found to be in acceptable condition (Figure 12). A slight downward trend in condition scores was apparent in the Cooper Creek over the monitoring period, reflecting the influence of exotic and translocated fish species, especially sleepy cod (Figure 11).

General trends in fish communities over the monitoring period were relatively similar across the Cooper Creek catchment following the large flood in 2010 (Figure 12). After this time, fish communities diverged between ecoregions according to the presence and availability of different habitats in each region (Table 6; Figure 12). In particular, small-bodied resilient species appeared to exploit the extensive aquatic habitats that were available during boom years (2011–2012), while larger, longer-lived resilient species dominated refuge habitats during bust years (2013–2016; Table 6). In some ecoregions (e.g. upper-mid Cooper), this transition occurred later and was more subtle than in others. In the lower Cooper, bust phase fish communities were also dominated by salt-tolerant Lake Eyre hardyhead, reflecting the saline condition of persistent aquatic habitats at this time (Table 6).

Thresholds of potential concern were triggered at a site scale in only four out of the 133 samples evaluated over the sampling period, including two samples at a single site (Figure 12; Appendix 3). These were associated with translocated and exotic species in all cases as follows:

• A decline in native fish diversity at Darr River in May and November 2014 comprising low numbers of native species and growing abundance of sleepy cod. It would be beneficial to monitor this site to determine potential impacts associated with the spread of sleepy cod

• Disproportionately high numbers of silver tandan at Windorah Bridge in August 2011, reducing overall native fish diversity. This pattern is consistent, nevertheless, with the boom and bust ecology of fish in Basin’s rivers (Balcombe & Arthington 2009). High numbers of goldfish present at this site may also be of concern. However, mass kills of this exotic species are likely during bust periods as resources become limited

• An unusually depauperate fish community, with no large-bodied and few resilient species, in Cullyamurra waterhole in November 2011. Low species diversity in this sample was caused by high levels of bony herring and high numbers of exotic gambusia and goldfish. This community is distinct from that previously found at Cullyamurra and more closely resembles that of an ephemeral floodplain fish community. However, given that this event occurred during the 2010–2012 flood and the fish community returned to the condition usually observed in the upper-mid Cooper in subsequent samples, this observation may be considered an anomaly driven by extreme hydrological variation.


Attribute thresholds of potential concern were triggered on 22 occasions in the Cooper catchment during the monitoring period, mostly in the upper and upper-mid Cooper ecoregions (Appendix 3). Eleven of these occasions were triggered by the spread of sleepy cod (i.e. this translocated species was found in samples where it had not previously been recorded), and five were triggered by a significant increase (more than two-fold) in the abundance of sleepy cod between consecutive sampling dates. Two thresholds of potential concern were triggered where exotic fish species dominated species richness or total abundance, while a further three were triggered by a lack of medium to small-bodied resilient fish species in ecoregions and hydro-climatic phases in which they were expected to be prevalent. Finally, a single threshold of potential concern was triggered by the absence of bony herring at a site, which is an unusual occurrence in the catchment, where salinity is relatively low.

Overall, the distribution and abundance of sleepy cod is the greatest concern in the Cooper Creek catchment throughout the Lake Eyre Basin Rivers Assessment monitoring, with range expansion indicating that this species has established a population throughout the entire catchment. Sleepy cod were also observed to proliferate at sites once established, particularly from 2015. The presence of this species in South Australia in 2016, especially in Coongie Lakes and Cullyamurra Waterhole, provides evidence that they are fast becoming a greater threat than initially thought.

An absence of most small to medium-bodied resilient fish at some sites in the upper Cooper during 2014 to 2015 is also of concern, with Hyrtl's catfish the only taxon present from this group in 2014–2015 samples. Further monitoring is required to determine whether increased abundance of sleepy cod is having a detrimental effect upon these native species or whether the absence of native species is the product of drying in the region at this time, given the more ephemeral nature of the tributaries of the upper Cooper.

Both occasions at Cullyamurra and Lake Hope where exotic taxa dominated fish communities were associated with extremely high numbers of gambusia during the 2011 flood period, indicating that conditions were conducive to the population growth of this exotic species. Given that numbers of gambusia dropped shortly thereafter, these events appear to be either short lasting effects or anomalies caused by hydro-climatic factors that would likely occur again in similar conditions. The frequency and intensity of these population events would beneficially be monitored in future to determine the impact of gambusia on native fish species and the effects of boom events on source populations of gambusia.


Table 6. Dominant fish species in monitored waterholes in the Cooper under boom and bust conditions between 2011 and 2016. Major causes of change in fish communities are also indicated.

Ecoregion Boom phase (2011–12) Bust phase (2013–16) Major drivers

Upper CooperSmall-bodied, resilient species (carp gudgeon, desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring)

Large-bodied resilient species (Lake Eyre yellowbelly), longer-lived resilient species (Hyrtl’s tandan) and species with resilient life-history and resistance to harsh conditions (bony herring and spangled perch)

Annual variability and persistence of habitats

Upper-mid Cooper

Large-bodied resilient species (Lake Eyre yellowbelly), longer-lived resilient species (Hyrtl’s tandan and silver tandan) and species with resilient life-history strategy and resistance to harsh conditions (bony herring)

A spatial trend was observed between upstream areas, dominated by large-bodied resilient species (Lake Eyre yellowbelly), to downstream reaches dominated by species with a resilient life-history (carp gudgeon, desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring).

Large-bodied resilient species (Lake Eyre yellowbelly), longer-lived resilient species (Hyrtl’s tandan) and species with resilient life-history and resistance to harsh conditions (bony herring) remained dominant.

Subtle changes in composition resulted in some species becoming less dominant (silver tandan).

Rare taxa (Cooper Creek tandan) and species with unpredictable occurrence (Australian smelt) dominated sites on two occasions.

Availability of deep waterholes

Lower-mid Cooper

Small-bodied species with a resilient life-history (desert glassfish, carp gudgeons, desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring, spangled perch)

Large-bodied resilient species (Lake Eyre yellowbelly), longer-lived resilient species (Hyrtl’s tandan, silver tandan) and species with resilient life-history and resistance to harsh conditions (bony herring)

Transition from widespread ephemeral habitats to limited persistent refuges

Lower Cooper

Small-bodied species with a resilient life-history (carp gudgeons, desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring and spangled perch)

Salinity tolerant taxa (Lake Eyre hardyhead) and species with resilient life-history and resistance to harsh conditions (bony herring)

Transition from widespread ephemeral habitats to limited saline habitats



Figure 12. Maps showing Biological Condition Gradient scores for fish communities at waterholes sampled in the Lake Eyre Basin Cooper Creek catchment between 2011 and 2016. Shading indicates ecoregions: upper Cooper (yellow), upper-mid Cooper (blue), lower-mid Cooper (green) and lower Cooper (red). Samples are represented by coloured dots, with condition scores represented by colour as per the legend. Red borders around some coloured dots indicate sites where thresholds of potential concern were triggered.

Georgina–Diamantina catchments

Six ecoregions were delineated in the Georgina–Diamantina catchments; the upper Georgina, upper-mid Georgina, the upper Georgina–Diamantina channel country, the lower Georgina–Diamantina channel country, the Goyder and the Warburton (Figure 13). Most fish communities were in good condition (scores 1–2) over the sampling period (Figures 11 and 13; Appendix 3). The lower Georgina–Diamantina channel country ecoregion had the best condition (i.e. good), while the Warburton ecoregion scored the lowest with the condition scores of some sites ranging from acceptable (scores 23) to good (scores 1–2) and some sites’ scores reflecting that they are in poor condition (scores 3–4; Figures 11 and 13).

A small, stepped decline in condition scores was apparent in the Georgina–Diamantina catchments from autumn 2012 (Figure 11). However, this merely reflects the addition into the Lake Eyre Basin Rivers Assessment program of Mungerannie Wetland, a refuge fed by an artesian bore, which scored poorly on all occasions due to low fish abundance and diversity and high proportions of exotic gambusia. Due to the modest number of sites sampled in each season within the Georgina–Diamantina catchments, the effect of the Mungerannie score on average catchment condition was disproportionately high. With this site excluded, average condition scores were classified as good.

Fish communities in the Georgina–Diamantina catchments are affected by a range of spatial and geomorphological factors. Sites of similar latitude and within similar geomorphic regions (e.g. the Mitchell Grass Downs region) tend to support similar fish communities across separate catchments. In contrast to the dramatic temporal patterns observed in the Cooper Creek catchment, major changes in fish communities were not observed in most ecoregions of the Georgina–Diamantina between the boom and bust phases (Table 7). The exception was the Warburton ecoregion, where stark changes in hydrology associated with drying and associated increase in salinity resulted in a shift in fish communities from being dominated by large-bodied resilient species (e.g. Lake Eyre yellowbelly) to being dominated by extremely tolerant species (e.g. Lake Eyre hardyhead and desert goby; Table 7, Figure 13).

Thresholds of potential concern were triggered at a site scale in only five out of 115 samples evaluated over the sampling period, with three of these occurring at Mungerannie wetland (Figure 13; Appendix 3). These were as follows:

• There is reduced species richness of native fish at Ooratippra Waterhole in autumn 2014. Given the position of this site in the upper Georgina, as well as the lack of significant flows in the preceding year, this unusual decline in native fish diversity may be attributed to reduced hydrologic connection with persistent waterholes in the vicinity, and it is likely to be within the range of natural variation for this site. Native fish species richness at the site had recovered in autumn 2015. Interpreting the monitoring results at this site also needs to consider that the geography of this site is distinct from other sites in the same Biological Condition Gradient ecoregion.

• There is a depauperate fish community at Pandie Pandie in May 2014 comprising few resilient species and low numbers of all but one species (Welch's grunter), which was present in moderate abundance. The absence of bony herring triggered this threshold of potential concern. This species was observed at this site only one


month earlier so its apparent absence in May could be a sampling anomaly (i.e. it may have been present but not detected).

• Depauperate fish communities, characterised by resistant fish species (bony herring, spangled perch and Lake Eyre hardyhead) and high proportions of invasive gambusia were observed at Mungerannie Wetland in autumn 2013, spring 2013 and spring 2014. These observations are typical for a bore-fed, artificial wetland and are consistently observed in other anthropogenic habitats in the Basin, including Poonaranna Bore (Warburton River), Tepamimi Waterhole (Eyre Creek), Old Peake Bore (Neales River) and the now decommissioned Big Blythe Bore (Neales River). Mungarannie Wetland and other poorly managed bores are of concern due to the opportunity they provide for source populations of the exotic gambusia to persist, and possibly to spread, under suitable conditions. None of these sites are designated as fixed Lake Eyre Basin Rivers Assessment monitoring sites, as they are not representative of the river habitats. Instead, surveys conducted at all these sites were made opportunistically while visiting Lake Eyre Basin Rivers Assessment sites or as part of other programs.

Nine attribute thresholds of potential concern were triggered in the Georgina–Diamantina catchments during the monitoring period (Appendix 3). These included three occasions in which large-bodied resilient taxa were absent where they were expected to be prevalent, such as in the upper reaches of the Georgina–Diamantina catchments. However, these observations likely reflect natural variation and are not cause for concern.

Two attribute thresholds of potential concern were triggered by unexpected reductions in the number of medium- to small-bodied resilient fish species in Old Cork Waterhole, in which only a single such species (Hyrtl's catfish) was observed in May 2014 and May 2015. In April 2016, only one other species (silver tandan) had returned to this site. A broader decline in small-bodied species throughout the upper channel country ecoregion, involving both desert glassfish and rainbow fish, was also observed throughout the 2014–2016 period, triggering thresholds of potential concern. These observations may be a cause for concern and future monitoring should assess if such declines are due to low detection rates or reflect actual species loss at these sites.


Table 7. Dominant fish species in monitored waterholes in the Georgina–Diamantina under boom and bust conditions between 2011 and 2016. Major cause of change in fish communities are also indicated.

Ecoregion Boom phase (2011–2012) Bust phase (2013–2016) Major drivers

Upper Georgina Small-bodied species with a resilient life-history (desert rainbowfish, desert glassfish, Hyrtl’s tandan, silver tandan) and species with resilient life-history and resistance to harsh conditions (bony herring)

No major change in fish community dynamics compared to the boom phase

A diverse range of habitats support a fairly consistent community

Upper-mid Georgina Large-bodied resilient species (Lake Eyre yellowbelly), resilient catfish (Hyrtl’s tandan, silver tandan) and species with resilient life-history and resistance to harsh conditions (bony herring)

Species with resilient life history and resistance to harsh conditions (bony herring) as well as large-bodied resilient species (Lake Eyre yellowbelly). Resilient catfish (Hyrtl’s tandan, silver tandan) are less dominant with drying.

Availability of large waterholes

Upper Georgina–Diamantina channel country

Species with a resilient life-history and resistance to harsh conditions (bony herring) as well as large-bodied resilient species (Lake Eyre yellowbelly); some small-bodied species with a resilient life-history (desert rainbowfish, desert glassfish) observed towards the lower section

No major change in fish community dynamics compared to the boom phase


Lower Georgina–Diamantina channel country

Resilient species, such as catfish (Hyrtl’s tandan, silver tandan), as well as large-bodied resilient species (Barcoo grunter and Lake Eyre yellowbelly)

Similar to that of boom phase but with increased dominance of bony herring (a resilient life-history strategist with a resistance to harsh conditions)


Goyder Large-bodied resilient species (Lake Eyre yellowbelly), longer-lived resilient species, (silver tandan and bony herring)

Large-bodied resilient species (Lake Eyre golden perch), longer-lived resilient species, (silver tandan, Hyrtl’s tandan, bony herring), with (Hyrtl’s tandan) appearing in 2014–15; one community was also dominated by gambusia in this period


Warburton Large-bodied resilient species (Lake Eyre yellowbelly), with some resistant species (desert hardyhead) particularly in downstream areas

A more resistant community developed with drying, where most communities dominated by extremely tolerant fish (desert hardyhead, desert goby) throughout the 2014–15 period

Transition from widespread ephemeral habitats to limited saline habitats



Figure 13. Maps showing Biological Condition Gradient scores for fish communities at waterholes sampled in the Georgina–Diamantina catchments between 2011 and 2016. Shading indicates ecoregions: upper Georgina (yellow), upper mid Georgina (purple), upper Georgina–Diamantina channel country (light blue), lower Georgina–Diamantina channel country (dark blue), Goyder (green) and Warburton (red). Samples are represented by coloured dots, with condition scores represented by colour as per the legend. Red borders around some coloured dots indicate sites where thresholds of potential concern were triggered.

Finke River catchment

Two ecoregions were delineated in the Finke River catchment: the Finke tributary and the Finke main channel (Figure 14). Most fish communities were scored as good (i.e. scores 1–2) to acceptable (2–3) condition over the sampling period (Figures 11 and 14; Appendix 3). Overall condition scores exhibited a slight decline in the Finke catchment during 2013–2014, mainly as a result of higher scores in the lower reaches of the main channel ecoregion. However, this decline in condition is not a cause for worry because it is associated with changes in fish abundance and diversity at two sites (Snake Hole and Salty Snakes Tail Waterhole), where natural rises in salinity occurred in response to drying.

Unlike other major rivers of the Basin, the Finke does not connect to Kati Thanda–Lake Eyre. As a result, a high proportion (three out of nine) species present in the Finke are endemic to this catchment and the fish community is consequently distinct from the rest of the Basin. The elevation and extent of the rocky upland catchment areas are also unique in the Basin, and most of the Finke River and its tributaries have sandy or rocky river beds, typically resulting in low turbidity in persistent waterholes. Saline groundwater is also an important influence in some parts of the catchment, and many waterholes become semi-saline to saline between flows.

While much of the Basin experienced a boom phase from 2010 to 2011 followed by a bust, hydrologic changes in the Finke catchment were less distinctive. Consequently, fish condition assessment was not undertaken in relation to hydro-climatic phases in this catchment. Instead, stable fish communities were observed across the Finke River catchment over the sampling period in both ecoregions. Despite the lack of a pronounced bust phase, hydrological variation was still an important context for interpreting monitoring data. Large flow events of 2010 and early 2011 were followed by a substantial dry period (2012–2014) with long gaps between flows and flows of small magnitude and duration. Wetter conditions returned in 2015 and 2016 (Table 8). The relative geographic proximity of samples (sampled waterholes are closer together than in some other catchments) is also likely to allow mobile species, such as spangled perch, to become widespread in this catchment, while periods of higher salinities probably facilitate the prevalence of tolerant species such as Finke hardyhead and barred grunter in drier periods (Table 8).

No thresholds of potential concern were triggered at a site scale within the Finke River catchment during the sampling period and the lowest condition score recorded was 2.8. However, five attribute thresholds of potential concern were triggered, all in the main channel ecoregion (Appendix 3).

• A single threshold of potential concern was triggered in autumn 2013 by the 18-month absence of Finke mogurnda at Lower Two Mile. However, this species had not previously been observed at that site at that time, probably due to the moderate to high salinities that are unfavourable for this species. Subsequent detection of this species at this site is thought to be the result of both river flows allowing dispersal as well as a temporary reduction in salinity resulting from fresh channel flows.

• Absence of Finke mogurnda from three sites during the following spring triggered a threshold of potential concern, although one of this species had never been detected previously at one of these sites. At Snake Hole, the water had become saline and therefore unfavourable for this species. This is probably a natural salinity cycle in Snake Hole and not cause for concern (Duguid 2013). At the third site (Three Mile), salinity was low and Finke mogurnda had been recorded there in the autumn by the Northern Territory Museum


(Bushblitz Survey of Henbury, May 2013). The reason for non-detection is unclear but may reflect low abundance or behavioural patterns. This species was caught in abundance at this site the following autumn, before connecting flows had occurred that would have allowed migration into the waterhole.

• Continued absence of Finke mogurnda from Snake Hole the following autumn (March 2014) also triggered a threshold of potential concern. This was again due to a natural increase in salinity at this site over a two-year period without flow.

• The absence of desert glassfish at Ormiston Gorge in autumn 2013 triggered a threshold of potential concern as the species had not been detected at this site for a period of 12 months. However, the site has only been sampled twice under the Lake Eyre Basin Rivers Assessment program (autumn 2012 and autumn 2013) and this species was not detected on either occasion. It is possible that desert glassfish are only occasionally present at this site and that more frequent sampling is required to establish trends in presence and absence. Consequently, no decline in condition is indicated by the triggering of this threshold of potential concern.

Table 8. Dominant fish species in monitored waterholes in the Finke River between 2011 and 2016. Major causes of change in fish communities are also indicated.

Eco-region Most sampling times and sites Exceptions Major drivers

Finke tributary(upper catchment only)

Moderately stable and characterised by mobile species (desert rainbowfish and spangled perch)

In Autumn 2014, one waterhole contained a suite of small-bodied resilient species (Hyrtl’s tandan, desert rainbowfish and bony herring).

Semi to near permanent waterholes allowing colonisation opportunities for mobile species

Finke main channel refuges

Small- to medium-bodied species with a resilient life-history (Hyrtl’s tandan, desert rainbowfish, desert glassfish and spangled perch) and species with resilient life-history and resistance to harsh conditions

Species with resilient life-history and resistance to harsh conditions (Finke hardyhead and barred grunter) in 2013 and 2014 (drier periods)

Availability of permanent waterholes, short distance between waterholes for dispersal and variability in amount and salinity of groundwater inputs

Macumba River catchment

All the monitoring waterholes in the Macumba catchment were grouped in a single ecoregion encompassing the main channel of the Macumba River and its tributaries. Most fish communities in the Macumba catchment were in good (i.e. scores 1–2) to acceptable (2–3) condition throughout the sampling period (Figures 11 and 14; Appendix 3).

The catchment lacks long term refuges (waterholes that persist for more than two years in the absence of flows). Consequently, the fish community is sustained in the long term by dispersal from the Georgina–Diamantina catchment when connecting flows join the Macumba River to the Kallakoopah (a lower reach of the Georgina–Diamantina) north of Kati Thanda–Lake Eyre. This favours highly mobile species such as spangled grunter and rainbowfish. During sustained boom phases, fish with poorer dispersal capabilities may enter the catchment from the Georgina–Diamantina.


Thresholds of potential concern were triggered at a site scale for two samples during the sampling period, both in Murdarinna waterhole. No fish were present in this site in autumn 2014 and, in autumn 2016, only a single species (spangled perch) was present. This site is in the upper reaches of the Macumba catchment and persists for less than a year without flow. The absence of fish at this site at these times reflects the lack of connectivity with downstream waterholes that might enable dispersal of fish to this site from other populations. Consequently, these observations appear to reflect the naturally occurring cycle of this waterhole and are not cause for concern.

Four attribute thresholds of potential concern were triggered over the sampling period in the Macumba River catchment (Appendix 3). Three of these were associated with the absent or depauperate fish community observed in Murdarinna waterhole, which is associated with limited connectivity as described above, and not considered to be cause for concern.

The Lake Eyre hardyhead was recorded within the Macumba catchment for the first time by the sampling. This species occurred in Andarrana Waterhole in autumn 2011, coinciding with the presence of numerous other species not typically observed within this catchment, notably smaller resilient taxa (desert glassfish and Lake Eyre hardyhead). Andaranna Waterhole is the furthest downstream site sampled within the catchment, lying 50 kilometres upstream of where the Macumba converges with Kallakoopah Creek. Consequently, it is not unexpected to encounter these species here during boom periods, as was experienced prior to 2011, as connectivity is likely to allow the dispersion of fish from the Kallakoopah and Warburton Rivers or from unidentified downstream saline refuges in the Macumba. Longer-distance dispersal of Lake Eyre hardyhead has been documented elsewhere in the Basin (Kerezsy et al. 2013).

Table 9. Dominant fish species in monitored waterholes in the Macumba River catchment under boom and bust conditions between 2011 and 2016. Major causes of change in fish communities are also indicated.

Boom phase (2011–2012) Bust phase (2013–2016) Major drivers

Dominated by mobile species with a resilient life-history (desert rainbowfish, bony herring and spangled perch)

A range of other species (Lake Eyre yellowbelly, Welch’s grunter, desert glassfish, Hyrtl’s tandan, silver tandan and desert hardyhead) were observed in the lowest Macumba sites (Andaranna and Winkies), which likely migrated from the Georgina–Diamantina catchment.

Dominated by mobile species with a resilient life-history (desert rainbowfish, bony herring and spangled perch)

All other species had disappeared.

Low persistence of waterbodies and high intensity, combined with low duration of hydrological events, enables species with strong migratory abilities to colonise rapidly into upstream reaches.

Neales catchment

Fish communities in the Neales catchment were generally in good (i.e. scores 1–2) to acceptable (2–3) condition over the sampling period (Figures 11 and 14; Appendix 3). Flows in this catchment tend to be localised and of short duration, providing relatively few opportunities for fish dispersal. Additionally, most waterholes in the catchment persist for less than two years in the absence of flow. Algebuckina Waterhole is the exception, but even this may dry completely or become very saline during extended droughts. Additional permanent artesian springs occur in this region, especially along the Peake Creek tributary, which connect to the main channel in periods of high flow.


Three ecoregions were identified in the Neales catchment (Table 10). The upper Neales ecoregion encompasses the upper tributaries of the Neales River and the main channel above Algebuckina Waterhole (Figure 14). In this ecoregion, fish communities during initial boom conditions (2011–2012) were dominated by smaller-bodied resilient and resistant taxa until waterholes dried in 2013 under bust conditions (Table 10). Species with strong dispersal abilities (e.g. spangled perch and desert rainbowfish) dominated fish communities in this ecoregion following the return of flows in 2015. Fish communities in the lower Neales ecoregion were more stable over the sampling period, and larger-bodied species were less abundant and widespread. In the lower Peake ecoregion, including the lower reaches of the Peake Creek from the Oodnadatta track crossing downstream to its confluence with the Neales (Figure 14), saline groundwater influxes to waterholes had a strong influence on fish communities, which tended to be dominated by resistant species and especially those tolerant of extreme conditions (e.g. desert goby and Lake Eyre hardyhead; Table 10).

Three thresholds of potential concern were triggered at a site scale in the Neales catchment over the sampling period (Figure 14; Appendix 3):

• There was an absence of fish in Hookeys Waterhole in April 2015, despite the occurrence of recent flows. This observation is likely to be a naturally occurring event, resulting from flows sufficient in size to refill the waterhole but too short to allow dispersal of fish from downstream refuges. Fish did return to this waterhole following flows in 2016.

• There was a depauperate fish community, with no large-bodied resilient species detected (Lake Eyre yellowbelly and Welch’s grunter), at Algebuckina Waterhole in November 2011. A more resistant fish community, lacking spangled perch and containing moderate abundances of Lake Eyre hardyhead and desert goby, was also developing at this site. This community was unexpected for this site during boom conditions, and it appears to be the result of seasonal drying over the preceding autumn–spring. Consequently, this observation could reflect natural variation and may not be cause for concern. Subsequent sampling in 2012 and 2013 consistently found large-bodied species and a gradual transition towards a more resistant fish community.

• There was a depauperate fish community dominated by exotic gambusia in Algebuckina Waterhole in April 2015. Water levels at this site were at their lowest for the monitoring period in spring 2013, after which localised flows occurred in summer 2013–2014. In the following autumn, significantly greater numbers of small resilient fish species were observed in Algebuckina Waterhole. Fish abundance then steadily declined as water levels gradually increased until spring 2014, after which the gambusia-dominated community was observed in autumn 2015. This chain of hydro-climatic events appears to have been conducive to the population growth of exotic gambusia, which emerges as a concern in this catchment.

Four thresholds of potential concern were triggered in the Neales catchment over the monitoring period (Appendix 3). These included two occasions when fish communities were dominated by the exotic gambusia, one occasion in which large-bodied resilient fish were absent under conditions in which they were expected (Algebuckina Waterhole), and one occasion in which resilient and resistent fish species were lacking when expected (Hookeys Waterhole in autumn 2015). As discussed above, only the abundance and extent of gambusia in the lower Neales and lower Peake ecoregions appear to be cause for concern in this catchment.


Table 10. Dominant fish species in monitored waterholes in the Neales catchment under boom and bust conditions between 2011 and 2016. Major causes of change in fish communities are also indicated.

Georgina–Diamantina ecoregion

Boom phase (2011–12) Bust phase (2013–16) Major drivers

Upper Neales Dominated by small-bodied species with resilient life-history (desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring)

Comparatively stable until 2013, when most waterholes dried completely. Following flows, 2015 populations were dominated by species with strong dispersal ability (spangled perch and desert rainbowfish).

Consistent ephemeral nature of habitats supports a consistent community in the absence of flow; flow periods allow dispersal by highly mobile species into these ephemeral habitats

Lower Neales Dominated by small-bodied species with a resilient life-history (desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring)

Dominated by species observed during the boom period (desert rainbowfish and bony herring) until spring 2013, when the fish community transitioned into that which resembles a more resistant community, dominated by salt-tolerant species such as desert hardyhead, desert goby and eastern gambusia, which are also contributing to the structure of the community.

Availability of large waterholes

Peake Prior to monitoring in 2010, the lower Peake fish community was dominated by small-bodied species with a resilient life-history (desert rainbowfish) and species with resilient life-history and resistance to harsh conditions (bony herring). The presence of these communities was short-lived, with some communities rapidly transitioning toward a more resistant community (desert hardyhead, desert goby) with eastern gambusia also dominating some communities in autumn 2011. Several resilient communities were observed prior to the end of the boom period (desert rainbowfish and bony herring).

Fish communities remained relatively stable, with resistant communities prevalent throughout (Lake Eyre hardyhead and desert goby); the exception was Warrarawoona waterhole, which dried and refilled more than once, with a corresponding return to a resilient fish community as local flow refilled the waterhole (desert rainbowfish and bony herring).

Annual variability and persistence of habitats and increased salinity during drying periods


.


Figure 14. Maps showing Biological Condition Gradient scores for fish communities at waterholes sampled in the Finke, Macumba and Neales catchments between 2011 and 2016. Shading indicates ecoregions: Finke Tributary and Macumba (yellow), upper Neales, Finke main channel (blue), lower Neales, Palmer (green) and lower Finke (red). Samples are represented by coloured dots, with condition scores represented by colour as per the legend. Red borders around some coloured dots indicate sites where thresholds of potential concern were triggered.

3.4.6 Coongie Lakes

The current limit of acceptable change set for fish in the Coongie Lakes site states that there should be ‘No less than eight of 13 native species recorded from any three of five comprehensive sampling events (assuming seasonal sampling) from the main branch and northwest branch, from the Queensland border downstream to Coongie Lakes and Embarka Swamp including Cullyamurra Waterhole’ (Butcher & Hale 2011).

This limit of acceptable change was informed by data from Puckridge et al. (2010), which indicated that 13 species of native fish had been recorded from the site and noted that most of these species are commonly observed in the upper reaches of the site upstream from Coongie Lakes. Because of incomplete knowledge of fish distributions across the site, this limit of acceptable change was only set for the upstream section of the main channel and north-west branch from Embarka Swamp and Coongie Lakes upstream to the Queensland border. The maximum acceptable level of change was selected on the basis of expert opinion, with acknowledgement that this limit would likely require refinement as ecological understanding increased through further data collection under the Lake Eyre Basin Rivers Assessment program (Butcher & Hale 2011).

The Lake Eyre Basin Rivers Assessment program sampling between 2008 and 2016 found eight or more native fish species in Coongie Lake sites on eight occasions (Table 11). If five consecutive sampling events are considered, as stated in the original limit of acceptable change, this threshold was exceeded on the four most recent sampling dates (Table 11), although it should be noted that only one or two sites (Coongie inflow and Cullyamurra waterhole) were sampled on the last six events.

A more refined approach to detecting unacceptable changes in fish communities upstream of Coongie Lakes can now be developed using the rules defined in the Biological Condition Gradient framework for the Cooper Creek catchment (see section 3.4.5). The single site monitored in the ecoregion of the Coongie Lakes (Coongie inlet in the lower-mid Cooper; Figure 13) was found to be in either good or acceptable condition throughout the six years of the Lake Eyre Basin Rivers Assessment monitoring. The recent appearance of sleepy cod emerges as a potential concern because this exotic predator may disrupt food web dynamics in aquatic ecosystems, and influence the abundance and diversity of native fish. The Biological Condition Gradient approach is more sensitive to such changes than the current limit of acceptable change, as it assesses the condition of fish communities relative to the expected abundance and diversity in any given hydro-climatic period. It would be beneficial for at least two sites in this ecoregion to be monitored in the future to better understand changes in fish communities in the Coongie Lakes region.


Table 11. Number of fish species captured and numbers of sites surveyed in comprehensive sampling events from the Queensland border downstream to Coongie Lakes and Embarka Swamp.

Year Season Number of species Number of sites

2008 Autumn 12 1

2009 Autumn 10 2

2010 Spring 10 2

2011Autumn 11 6

Spring 10 6

2012Autumn 12 11

Spring 5 1

2013Autumn 7 2

Spring 6 1

2014Autumn 7 2

Spring 8 1

2015 Autumn 11 2

2016 Autumn 7 2


3.5 Waterbirds

3.5.1 Key messages

• Slight increases in the numbers of waterbirds and the number of species was apparent across the eastern catchments of the Lake Eyre Basin over 33 years of surveys. Increased abundances in some waterbird groups (piscivores and herbivores) and some species were also apparent. In contrast, significant declines in total numbers and the abundance of many species were apparent over the same period in the Murray–Darling Basin.

• The only long-term declines in waterbird abundances detected in the Basin’s eastern catchments were for shorebirds at three wetlands (Goyders Lagoon, lower Cooper and Lake Yamma Yamma). There is increasing evidence for decline of migratory shorebirds in Australia, affected by changes to habitats in their flyways and within Australia. Herbivorous waterbirds on Lake Katherine and brolgas also showed declines in the Georgina–Diamantina catchment.

• A total of 46 waterbird species were observed in the eastern Basin between 1983 and 2015. Ducks tend to be the most abundant group, followed by herbivores, piscivores, shorebirds and large wading birds.

• Waterbird numbers and diversity are highly variable at the scale of the Basin, at catchments and at individual wetlands, largely reflecting boom and bust ecology and the consequential variability in streamflow and wetland water levels. In general, more waterbirds and waterbird species occurred in the Cooper Creek catchment than in the GeorginaDiamantina catchment.

• Although the long-term monitoring data for waterbirds in the Basin’s eastern catchments did not provide a definitive indication of the condition of wetlands and rivers in western parts of the Basin, these catchments are similarly maintained in a relatively unaltered state and so it is considered that the waterbird survey in the eastern catchments adequately reflects aspects of the Basin’s broader condition.

• Waterbirds were surveyed across the Coongie Lakes region (Cooper catchment) in November 2008 during widespread drought conditions in the Basin. High numbers of waterbirds (almost 60,000) and waterbird species (about 45) were present, including around 2 per cent of the total populations of red-necked avocet and pink-eared duck. These results support the continued recognition of this site as internationally significant. Lake Galilee (Cooper catchment) was the most important of the wetlands assessed through the Eastern Waterbird Aerial Survey (1983–2015) with respect to waterbird abundance, averaging around 35,000 waterbirds a year during wet periods.

3.5.2 Overview—eastern catchments

Waterbirds have been surveyed in the Cooper and Diamantina–Georgina catchments every spring since 1983 as part of the Eastern Aerial Waterbird Survey (Figure 15 and Table 12). The survey is made along fixed flight paths (Figure 15) along which waterbirds are counted on every wetland larger than one hectare that falls within the 30 kilometre-wide survey band. The Lake Eyre Basin part of the survey crosses ten major wetlands (marked on Figure 15 and listed in Table 12). Only the parts of wetlands within the survey band are counted, so counts for individual wetlands are not all total counts. The Coongie Lakes complex is not included but a separate aerial survey was conducted in 2008.


A total of 46 waterbird species has been observed in the Lake Eyre Basin during the aerial surveys (Appendix 4), with an average of 37 species recorded each year. At a catchment scale, fewer species are generally recorded, with an average of 32 species per year observed in the Cooper Creek catchment and 28 species per year in the GeorginaDiamantina. The number of waterbird species varies considerably between years, however, with greater variability observed at a catchment scale than at the Basin scale (Figure 16).


Figure 15. Aerial survey paths across the Georgina–Diamantina catchment (blue) and Cooper Creek catchment (purple) and the 10 wetlands listed in the table below (Kingsford et al.2016).

Table 12. Ten key wetlands included in the annual waterbirds survey (Kingsford et al. 2016).

Site Catchment State

Lower Cooper (CP) Cooper Creek South Australia

Lake Dunn (LD) Cooper Creek Queensland

Lake Galilee (LG) Cooper Creek Queensland

Lake Hope (LH) Cooper Creek Queensland

Lake Yamma Yamma (LY) Cooper Creek Queensland

Goyders Lagoon (GL) Georgina–Diamantina South Australia

Lake Katherine (LK) Georgina–Diamantina Queensland

Lake Mumberry (MU) Georgina–Diamantina Queensland

Lake Phillippi (LP) Georgina–Diamantina Queensland

Lake Torquinnie (LD) Georgina–Diamantina Queensland

The total number of waterbirds is also highly variable between years (Figure 16). High numbers typically occur at times of high streamflow, reflecting widespread inundation and habitat availability (Costelloe et al. 2005). Waterbird numbers tend to be lower on average in the Georgina–Diamantina catchment (about 33,000) than in the Cooper Creek catchment (about 65,500).

Ducks were the most abundant functional group recorded at both the Basin and catchment scale between 1983 and 2015, followed by herbivores, piscivores, shorebirds and large wading birds (Figure 16). From 1983 to 2015, reflecting overall abundances, there were fewer numbers of waterbirds in each of the functional groups in the Georgina–Diamantina than in the Cooper Creek catchment. Waterbird abundances (totals, and of the functional groups) were more variable between the years in the Georgina–Diamantina catchment.

Waterbird abundance and diversity also varied considerably within individual wetlands, although the relative proportions of different suites of birds within each wetland tend to be similar over time at this scale (Figure 17). Lake Galilee was by far the most important wetland assessed through the Eastern Waterbird Aerial Survey in the Basin (the survey does not cover Coongie Lakes) with respect to waterbird abundance, with an average of almost 35,000 waterbirds observed annually during wet periods (Figure 17). During the survey period, some wetlands were dry for long durations and did not support any waterbirds.


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Figure 16. Estimates of abundance of waterbirds during annual aerial surveys across eastern Australia over 33 years (1983–2015) in the Lake Eyre Basin (a); the Georgina–Diamantina catchment (b); and the Cooper Creek catchment (c); showing: species richness (dashed line), total abundance (grey fill) and abundances of each of the five functional groups (ducks, red), herbivores (green), large wading birds (purple), piscivores (light blue), and shorebirds (orange).


Figure 17a. Estimates of waterbirds during annual aerial surveys across eastern Australia over 33 years (1983–2015) for each of the five wetlands surveyed in the Georgina–Diamantina, showing: species richness (dashed line), total abundance (grey fill) and abundances of each of the five functional groups (ducks, red), herbivores (green), large wading birds (purple), piscivores (light blue), and shorebirds (orange) for the five wetlands: Lake Katherine (LK), Lake Philipi (LP), Lake Mumberry (MU), Lake Torquinnie (LT) and Goyders Lagoon (GL). Note that these estimates are not total counts, as aerial survey bands sometimes do not include entire wetlands.

Figure 17b. Estimates of waterbird communities during annual aerial surveys across eastern Australia over 33 years (1983–2015) for each of the five wetlands surveyed in the Cooper Creek Catchments, showing: species richness (dashed line), total abundance (grey fill) and abundances of each of the five functional groups (ducks, red), herbivores (green), large wading birds (purple), piscivores (light blue), and shorebirds (orange) for the five wetlands: Lake Galilee (LG), Lake Dunn (LD), Lake Yamma Yamma (LY), Lake Hope (LH) and Lower Cooper Lakes (CP). Note that these estimates are not total counts, as aerial survey bands sometimes do not include entire wetlands.

3.5.3 Temporal trends

Long-term trends in total waterbird numbers, numbers of species and the abundances of waterbird functional groups were investigated for the both the Lake Eyre Basin and the neighbouring MurrayDarling Basin. For the Lake Eyre Basin, only 15 out of 91 identified trends were found to be statistically significant and, of these, only four were negative. All negative trends involved reductions in the abundance of shorebirds at three wetlands (Goyders Lagoon, Lower Cooper and Lake Yamma Yamma), consistent with evidence of long-term declines in shorebird abundance across Australia (Nebel et al. 2008; Clemens et al. 2016).

Across the Basin, slight increases in total waterbird numbers (an average annual gain of 0.76 per cent) and the number of waterbird species were apparent between 1983 and 2015. At a catchment scale, neither total waterbird numbers nor numbers of species exhibited significant long-term trends in either the Cooper or GeorginaDiamantina catchments, although a significant increase in the abundance of piscivores was detected in the Cooper Creek catchment (an average annual gain of 1.10 per cent). In contrast, observations of waterbird numbers in the MurrayDarling Basin indicate an average annual decline of 3.93 per cent and a 72 per cent decline in total waterbird numbers over the 33-year period (Kingsford et al. 2016). Declines were particularly severe in the MurrayDarling Basin among ducks and shorebirds (Kingsford et al. 2016).

At the wetland scale, positive long-term trends were detected for the number of species (average increase of 1.05 per cent) and total number of waterbirds (average increase of 2.86 per cent) in Lake Hope and number of species (0.52 per cent) in Lake Katherine. The number of herbivores also increased over the survey period in Goyders Lagoon (1.64 per cent) and Lake Hope (3.07 per cent) while the number of piscivores grew in Lake Dunn (1.34 per cent) and Lake Hope (3.83 per cent; Figure 18).

Long-term trends in the abundance of particular waterbird species in the Basin were also investigated. A decline was only detected in one species (brolga) and this only occurred within the GeorginaDiamantina catchment. At a Basin scale, three species (pied cormorant, Pacific black duck and an unidentified tern species) increased in abundance over the survey period while three species (pied cormorant, little pied cormorants and large waders) exhibited increases in the GeorginaDiamantina catchment, and four species (pied cormorant, royal spoonbill, brolga and tern) in the Cooper Creek catchment. Interestingly, two of these species (Pacific black duck and little pied cormorant) exhibited significant declines over the same period in the MurrayDarling Basin.



Figure 18. Mean (± 95% confidence limits) annual trends, as a percentage of average abundance, for different waterbirds (total abundance, species richness and abundances) of the five functional groups (ducks, herbivores, large wading birds, piscivores, shorebirds), estimated during annual aerial surveys across eastern Australia over 33 years (19832015) for a) five wetlands within the GeorginaDiamantina river catchment (Lake Katherine (LK), Lake Philipi (LP), Lake Mumberry (MU), Lake Torquinnie (LT) and Goyders Lagoon (GL)), and for b) five wetlands within the Cooper Creek catchment (Lake Galilee (LG), Lake Dunn (LD), Lake Yamma Yamma (LY), Lake Hope (LH), Lower Cooper Lakes (CP)). Note that these estimates are not total counts as aerial survey bands sometimes do not include entire wetlands.

3.5.4 Coongie Lakes

Waterbirds in 21 wetlands in the Coongie Lakes Region of the Innamincka Regional Reserve were surveyed in November 2008 (Kingsford et al. 2012) during a period of widespread drought in the Lake Eyre Basin and MurrayDarling Basin. During this survey, over 58,000 waterbirds were recorded representing at least 45 species (Appendix 5). Overall, ducks were the most abundant group observed, followed by piscivores, shorebirds and large wading birds (Figure 19). Waterbird numbers varied considerably between individual wetlands, with larger lakes supporting higher numbers and more species of waterbirds.

The results of this survey indicate that Coongie Lakes is likely to meet the waterfowl abundance criterion for listing as a Ramsar site (because it regularly supports 20,000 or more waterfowl), even though the site was not originally listed under this criterion (Butcher & Hale 2011). Coongie Lakes is also considered internationally significant in that it regularly supports one per cent of the individuals of one species or subspecies of waterbird (Butcher & Hale 2011). In the 2008 survey, 2,521 red-necked avocets and 21,670 pink-eared ducks were recorded in the Coongie Lakes region, representing just over two per cent of the total estimated populations of each of these species.


Figure 19. Total counts of waterbirds on Coongie Lakes during aerial surveys in 2008, separated into functional groups.

3.5.5 Western catchments

The long-term monitoring for waterbirds in the Basin’s eastern catchments does not provide a definitive indication on the condition of wetlands and rivers in western parts of the Basin. As these catchments are similarly maintained in a relatively unaltered state, the waterbird survey in the eastern catchments is considered to reflect aspects of the Basin’s broader condition (R. Kingsford, pers. comm.).

The Basin’s western catchments are likely to have more variable waterbird numbers and diversity of wetlands compared to eastern catchments, given that the western wetlands hold water more episodically (R. Kingsford, pers. comm.). In the Northern Territory portion of the Basin, the larger wetlands and groups of wetlands are filled less frequently than those in the Basin’s eastern catchments, and a summary of the waterbird data for these wetlands indicates that they episodically support substantial numbers of waterbirds and considerable diversity (Duguid et al. 2005).


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