The Lake Eyre Basin Rivers Assessment (LEBRA) has been established to address a requirement of the Lake Eyre Basin (LEB) Intergovernmental Agreement (2000) to review and report on the condition of the watercourses and catchments within the LEB Agreement Area on a 10 yearly basis. The first condition assessment was the State of the Basin 2008: Rivers Assessment (LEBSAP 2008, 2009).
A core component of the LEBRA is the annual monitoring program which operates under the 'LEBRA Implementation Plan 2010-2018' endorsed by LEB Ministerial Forum in April 2010.
The LEBRA monitoring program collects the hydrological and ecological data needed to determine the condition of the watercourses and catchments within the LEB. The annual monitoring of fish, water quality and hydrology commenced in 2010/11.
This report presents the monitoring results from spring 2013 and autumn 2014 (2013/14 financial year). The scope of this report is set by the 2014 LEBRA Project Plan (DotE 2015) and follows the precedents of the 2011, 2012 and 2012/2013 Monitoring Reports (Cockayne et al., 2012, 2013, and Sternberg et al., 2014 respectively).
Monitoring was undertaken by the South Australian Research and Development Institute (SARDI), Queensland Department of Natural Resources and Mines (DNRM) and Northern Territory Department of Land Resource Management (DLRM).
Hydrology and water quality
Hydrological data were collected from 32 hydrological gauging stations throughout the basin and an additional 22 conductivity/temperature/depth data loggers established by the LEBRA monitoring program. The report shows that flows during the 2013/14 reporting period were lower in magnitude and of shorter duration than in previous reporting rounds. Flow volumes varied across the LEB; however, none of the sites experienced 'big' or long lasting flow events. Consequently inundation beyond defined channels (i.e. flooding) did not occur or was of minor extent. A number of sites experienced prolonged drying over the 12 month reporting period. Some sites were completely dry, while for others, it is unknown whether complete waterhole drying occurred.
Catchment results are summarised below:
- Many sites in the Georgina catchment experienced drying during the 2013/14 sampling round. A small flow event during December 2013 rewetted several sites but was insufficient to reach all monitoring sites in the catchment. A stronger flow in February 2014 reached all monitored sites in the catchment.
- Most of the Diamantina and Warburton catchment flowed in early 2014 refilling many previously dry waterholes and reaching the highest discharge that has been observed at the Diamantina Lakes since commencement of LEBRA. This flow was not observed in the most downstream monitoring station or logger.
- In the Cooper and Barcoo catchments a number of sites appeared to completely dry over the summer 2013/2014 period. The majority of sites in the catchments then experienced flow prior to fish sampling in May 2014. These flows, originating from heavy rains in the upper catchment throughout February, were large enough to cause connectivity over much of the catchments' upper to lower reaches.
- A small pulse flow was observed on the Finke River main channel during April 2014 but did not reach the monitoring sites downstream.
- Before the reporting period the upper and lower Macumba River gauging sites had dried. In April 2014 a localised flow event filled the lower Macumba.
- The upper Neales catchment remained dry throughout 2013/14. In February 2014 the lower Neales River at Algebuckina flowed due to a localised rain event that occurred only within two small tributary catchments.
Water quality parameters (temperature, dissolved oxygen, conductivity, pH and turbidity) were collected at each fish monitoring site and found to be within the range of tolerance for fish species in the LEB.
Fish populations were monitored using the agreed LEBRA methods. A total of 44 fish monitoring sites were sampled (17 sites in spring 2013 and 41 sites in autumn 2014).
Key results of fish monitoring in 2013/14 are listed below.
- A total of 112,525 fish from 19 native, one translocated and two exotic species were processed over the two sampling occasions.
- Fish species richness for the major river systems (catchments) varied from 3 species in the Macumba River to 18 species in Cooper Creek.
- Highest recorded catch of fish was 23,089 at Cowarie Crossing (Diamantina Catchment) in spring 2013. The lowest was 18 fish at Old Cork Waterhole (Diamantina catchment) in autumn 2014.
- The total abundance of fish was 4 to 5 times greater than previous years, driven primarily by very large catches of Lake Eyre hardyhead (Craterocephalus eyresii) in the lower Cooper and Diamantina catchments.
- Similar to previous years, exotic species accounted for less than 1% of the total catch on both sampling occasion, (829 individuals), with eastern gambusia (Gambusia holbrooki) the most abundant and widespread exotic species (789 individuals, 9 sites).
- The Neales catchment had the highest proportion of exotic species (6.9%) with no exotics caught in the Finke, Macumba and Georgina catchments.
- Disease was recorded in 32 individuals from 6 species.
- Disease was only detected in the Cooper and Diamantina catchments with disease rates comparable to previous years.
The 2013/14 round of LEBRA monitoring adds to the basin-wide dataset that has been collected using consistent methods since autumn 2011. The program has created novel baseline data for many waterholes, tributaries, and in some cases whole river systems. The program also includes sites with pre-existing monitoring histories. Results reported here further update knowledge of fish distribution and population dynamics across the basin. Expanded interpretation including multi-year comparisons, consideration of the context of results and a review of Thresholds of Potential Concern will be undertaken in the analysis for state of the basin reporting.
The continued involvement in the monitoring program of the Tjuwanpa Rangers in the Finke catchment and the Dugalunji Aboriginal Corporation in Queensland was an important outcome for Indigenous participation in LEBRA.
Data collected under the LEBRA was used to analyse spawning cues in Lake Eyre golden perch (Macquaria sp.) resulting in a publication the journal of Marine and Freshwater Research (Cockayne et al., 2015).
The Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) was engaged to develop a riparian weed assessment and monitoring methodology that could be undertaken by Rangers from the Dugalunji Aborginal Cooperation throughout the Cooper, Georgina and Diamantina catchments (James, 2015). A trial was conducted in September 2014 using the draft methodology.
This report does not summarise all current environmental research in the Lake Eyre Basin Rivers. Agencies undertaking the LEBRA Monitoring Program also do other survey work in the Basin, some of which is referred to in this report but results are not systematically reported here.