Warburton Creek, Yelpawaralinna Waterhole
2012 Aquatic Ecosystem Condition Report
- Permanently wet, non-flowing, creek site when sampled in spring 2012
- Moderately diverse macroinvertebrate community with several rare and sensitive species collected
- Water was very fresh, turbid and enriched with nutrients
- Riparian vegetation consisted of native trees and shrubs but no aquatic plants were recorded from the waterhole
About the location
Warburton Creek forms downstream from the confluence of the Diamantina and Georgina rivers in Goyder Lagoon, in the north of South Australia, and flows in a south-westerly direction for about 150 km before discharging into Lake Eyre. Both inflowing rivers rise in central west Queensland and flow south-west for about 900 km through central Queensland and the ‘channel country’ before merging into the one well-defined channel downstream from Goyder Lagoon.
Flow patterns in the unregulated Warburton and upstream catchments are highly variable and driven by monsoonal summer rainfall in the upper catchment area of Queensland. The Diamantina River, along with Cooper Creek, are among the most variable major rivers in the world, characterised by ‘boom’ (major floods) and ‘bust’ (major dry periods and drought) climatic cycles. In extremely wet years when rainfall reaches around 500 mm year across much of the upstream catchments, water flows down the Warburton River and reaches as far downstream as Lake Eyre. Large stretches of the Diamantina and Georgina rivers have little reliable water but a small number of widely-spaced permanent and semi-permanent freshwater waterholes occur throughout each river system. Most waterholes on Warburton Creek, in contrast, tend to go saline within 6-12 months of filling but a few waterholes such as Yelpawaralinna, Cowarie, Anarowidinna and Emu Bone hold freshwater for many months following flooding flows (for more details see Silcock 2009 – under the Further Information heading).
The major land use along Warburton Creek is cattle grazing.
The monitoring site was located on a track off the Birdsville Track, about 80 km south-west from Goyder Lagoon and 100 km north from Mungeranie in the Far North of South Australia.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was evidence of human disturbance including nutrient enrichment and stock access to the water but the stream provides habitat for several rare and sensitive species of macroinvertebrates. Note that the high nutrient concentrations recorded from the waterhole were similar to other sites sampled from the Diamantina River and were assumed to have originated from upstream grazing and cropping practices. Similarly, the high turbidity was presumably sourced by floods naturally mobilising clays from the channels and flood-out areas in Queensland and was not obviously exacerbated by local land use practices.
A moderately diverse community of at least 11 species of macroinvertebrates was collected from the 150 m wide, non-flowing, arid-zone waterhole in spring 2012. The community was dominated by low to moderate numbers of waterbugs (Micronecta and Anisops thienemanni) but included smaller numbers of 4 types of chironomids (Coelopynia, Harnischia, Cricotopus and Paratanytarsus), and a freshwater prawn (Macrobrachium australiense), a mite from the Family Limnesiidae, beetle (Sternopriscus multimaculatus), caenid mayfly (Tasmanocoenis) and gomphid dragonfly (Austrogomphus). The assemblage was dominated by tolerant insect groups such as waterbugs and chironomids that are commonly found in other waterholes in the region. The only regionally rare macroinvertebrates recorded were the mite, two chironomids (Coelopynia and Harnischia) and the dragonfly nymph, and the only sensitive group recorded was the mayfly. No fish were caught or seen at the site when it was sampled in October 2012.
The water was fresh (salinity of about 182 mg/L), well oxygenated (101% saturated) and very turbid (secchi depth 3 cm), with high concentrations of nutrients such as nitrogen (4.1 mg/L) and phosphorus (1.2 mg/L).
The sediments were dominated by clay, with smaller amounts of detritus, silt and sand; samples taken from below the surface were grey clays and silts and showed no signs that the sediments were anaerobic, or lacking in oxygen. No evidence of any bank erosion was noted but cattle faeces were recorded from the edges of the waterhole and on the banks in places.
A moderate amount of phytoplankton was present (chlorophyll a 7.8 Âµg/L) but no green filamentous algae or aquatic plants were recorded growing in the waterhole. The riparian vegetation was dominated by gums, lignum and acacias on the moderately vegetated banks (50-79% vegetative cover). The surrounding vegetation comprised scattered gum trees over native shrubland.
Special environmental features
Yelpawaralinna Waterhole provides an important refuge habitat for aquatic macroinvertebrates in the region and probably also supports a wide range of native fish and other aquatic species from the Diamantina catchment.
Pressures and management responses
|Livestock have direct access at the site and upstream in the catchment exerting excessive grazing pressure on vegetation, causing sediment erosion and adding some nutrients to the watercourse.||The SA Arid Lands Natural Resources Management Board recognizes that both direct and diffuse impacts on aquatic ecosystem condition can occur through direct stock access and excessive grazing pressure from stock and feral herbivores. Technical advice and incentives are offered to land managers in the region, as funding permits, to address these impacts through appropriate activities suitable for the context. In addition, projects are underway across the region to identify, prioritise and address impacts at key aquatic sites.|
|High nutrient concentrations causing excessive algal growth although the source(s) of all the nutrients is not known with certainty.||The EPA in collaboration with the Department for Environment, Water and Natural Resources is anticipating a study program to investigate the source(s) of nitrogen and phosphorus. This will provide a better understanding of nutrient dynamics with the aim of developing a management strategy (if appropriate).|
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- Silcock, J. (2009). “Identification of Permanent Refuge Waterbodies in the Cooper Creek and Georgina-Diamantina River Catchments for Queensland and South Australia.” Final report to South Australia Arid Lands Natural Resource Management Board.