The Lake Eyre Basin Rivers Assessment (LEBRA) is a monitoring program designed to gain an understanding of, and report on, the condition of watercourses and catchments in the Lake Eyre Basin (LEB) as required under the LEB Intergovernmental Agreement. The aim of this report is to present monitoring from 2011 which was the first year of the current monitoring program. The scope of this report is set by the 2011 LEBRA Project Plan (SEWPaC 2011). The current phase of the LEBRA monitoring operates under the 'LEBRA Implementation Plan 2010-2018' which was endorsed, in principle, by LEB Ministerial Forum in April 2010. A more comprehensive scientific report that assesses the condition of LEB watercourses and catchments will be produced in 2014 as part of the mid-term assessment required under the LEBRA Implementation Plan.
The 2011 LEBRA Project Plan identified the monitoring indicators for the 2011 LEBRA as hydrology, water quality and fish. Monitoring was undertaken in autumn 2011 by the South Australian Research and Development Institute (SARDI) Aquatic Sciences Division, Queensland Department of Natural Resources and Mines (DNR&M) and Northern Territory Department of Natural Resources, Environment, the Arts and Sport (NRETAS).
Hydrology and water quality
Data was collected from 30 hydrological gauging stations throughout the basin and an additional 18 conductivity/temperature/depth loggers where installed in areas lacking hydrological monitoring. Comprehensive GIS-based bathymetric surveys were conducted at 8 waterholes.
Above average rainfall resulted in three consecutive years of above average flows in LEB catchments. Extensive floodplain and floodout inundation occurred in lower reaches of each of the major rivers (Cooper, Diamantina, Georgina, Finke and Neales) with associated flow into Lake Eyre. Most sites did not experience significant dry spells, to the extent that no monitoring sites dried completely in the two seasons leading up to the monitoring program. Water quality parameters (temperature, dissolved oxygen, conductivity, pH and turbidity) were collected at each fish monitoring site and were found to be within the range of tolerance for fish species in the LEB.
A structured monitoring methodology was applied consistently throughout the LEB. This provided novel baseline data for many waterholes, tributaries, and in some cases whole river systems; updated data on fish distribution and abundance from sites previously studied; and, continuing data for long-term monitoring sites. A total of 44 fish monitoring sites were sampled using the LEBRA fish monitoring methodology. Key fish results were:
- Nineteen species of fish were recorded, including 17 native and 2 introduced exotic species (goldfish and eastern gambusia).
- Site fish diversity ranged from 1 to 12 species.
- In many catchments and sub-catchments species were recorded for the first time (5 in the Macumba, 1 in the Neales, 3 in the Ooratippra, 1 in the Rankin, 4 in the Sandover).
- Recent years of consistent river flows in all catchments promoted species recruitment, as demonstrated by fish size-classes and, in some cases, very high fish abundances (up to 52,000 fish caught at one site).
- Disease levels and fish kills were low in most catchments, with the exception of some Queensland sites where diseased fish represented up to 80% of the total catch.
- The data collected for the Northern Territory sites were the first systematic population oriented sampling for most sites and added to the list of species known at most waterholes;
- The data collected for the Sandover River Catchment (Sandover River and Ooratippra Creek) were the first systematic fish survey of any kind in the catchment.
- Fish species assemblages were unique in the Finke River, with the highest proportion of species endemic to a river catchment.
- Fish species assemblages in the Upper Macumba were characterised by low species diversity, with rainbowfish, bony bream and spangled perch making up most of the catch.
- The lower Macumba and the majority of the Georgina, Diamantina and Cooper catchment sites all contained higher diversity of fish species.
In addition to the data collected during 2011, the involvement of the Tjuwanpa Rangers in the monitoring program was an important outcome for indigenous participation in LEBRA. With continued involvement, they will be an important factor in keeping the LEBRA monitoring program viable in the Northern Territory segment of Lake Eyre Basin.
The implementation of the 2011 LEBRA monitoring program enabled the testing of the fish sampling methodology. Survey techniques for catching some species of fish (e.g. Finke endemic species and desert goby) need further development to increase confidence in catch and to obtain meaningful scientific data for these species. Improvements to the fish monitoring protocols will be incorporated in the 2012 LEBRA Project Plan.
The 2011 round of LEBRA monitoring successfully implemented a consistent basin-wide sampling regime for the first time. The 2011 monitoring provides a basis for the 2012 LEBRA monitoring program and for potential expanded monitoring in the future.