Permanently wet, non-flowing, creek site when sampled in spring 2012
Moderately diverse macroinvertebrate community with two rare or sensitive species collected
Water was very fresh, turbid and enriched with nutrients
Riparian vegetation consisted of native trees and shrubs but the sparsely vegetated understorey was dominated by an introduced grass
Area map
About the location
Cooper Creek is a large stream in the Far North that rises at an altitude of 230 m in western Queensland and flows south-westerly for over 1,500 km through increasingly arid woodland, grassland and desert before discharging into Lake Eyre. In the ‘channel country’ of the middle reaches, it forms both deep, narrow channels which transport sand and mud at moderate flows and a large network of braided channels that transport clay-rich mud during high flow periods. As the river passes into South Australia it forms the one channel near Innamincka and then further downstream it extends across a wide floodplain and forms another mosaic of shallow freshwater and saline lakes, deep permanent and semi-permanent channel reaches, flooded woodlands and grasslands, samphire-lined claypans and other wetlands (for more details see Walker et al. 1997 and Silcock 2009). Flow patterns in the unregulated Cooper Creek are highly variable and driven by monsoonal summer rainfall in the upper catchment area in Queensland. Most water is retained or evaporates in the channel country and only 30% of overbank flows reaches Innamincka. As a result, Lake Eyre only receives water during extremely large floods.
The major land uses in the 296,000 square kilometre catchment are sheep and cattle grazing on native grasslands, with smaller areas used for rural towns and settlements, mining, tourism and national parks.
The monitoring site was located off the Coongie Track on the north-west branch of Cooper Creek, about 65 kilometres north-west from Innamincka.
In summary
The creek was given a Fair rating because the site sampled showed evidence of moderate changes in ecosystem structure, and some changes to the way the ecosystem functions. Therewas evidence of human disturbance including nutrient enrichment and weeds dominating the understorey vegetation on the banks but the stream still provided habitat for a moderately diverse macroinvertebrate community. Note that the high nutrient concentrations recorded from the waterhole were similar to other sites sampled from Cooper Creek and were assumed to have originated from upstream grazing and cropping practices. Similarly, the high turbidity was sourced by floods naturally mobilising clays from the channel country in Queensland and was not obviously exacerbated by local land use practices.
Findings
A moderately diverse community of at least 18 species of macroinvertebrates was collected from the 60 m wide, non-flowing, arid-zone waterhole in spring 2012. The community was dominated by moderate numbers of freshwater prawns (Macrobrachium) and caddisflies (Triplectides australis) and included low numbers of 6 species of beetles, 5 waterbugs, 2 snails, baetid mayflies, worms and yabbies. The site sampled was notable because it lacked any dipterans, odonates and mites, groups that commonly occur at other locations on Cooper Creek. The site provided habitat for at least one rare species, a snail from the Family Thiaridae and a sensitive species of mayfly (Cloeon) that is widely distributed throughout the eastern Lake Eyre Basin. A small number of carp gudgeons (Hypseleotris) were the only fish caught at the site in 2012.
The water was fresh (salinity of about 160 mg/L), well oxygenated (12.6 mg/L) and turbid (secchi depth 8 cm), with high concentrations of nutrients such as nitrogen (2.88 mg/L) and phosphorus (0.48 mg/L).
The sediments were dominated by detritus, with smaller amounts of clay, silt and sand also present; samples taken from below the surface were sulfidic grey clays and silts, indicating that they were anaerobic and lacked oxygen. No evidence of any significant bank erosion was noted.
A large amount of phytoplankton was present (chlorophyll a 52 µg/L) which included a significant amount of cyanobacteria or blue-green algae (chlorophyll b 8.6 µg/L). No filamentous algae were observed at the site sampled. Over 10% of the edge of the waterhole was covered by introduced couch grass but no other aquatic plants were recorded. The riparian vegetation was dominated by gum trees over lignum and acacias, with couch grass growing in the understorey in patches; only 25-49% of the banks were vegetated. The surrounding vegetation at the site was low gum and acacia woodland that was used for grazing cattle and recreational camping.
Special environmental features
Cooper Creek in the vicinity of Kudramitchie Waterhole provides an important permanent refuge habitat for a diverse range of aquatic macroinvertebrates from the region and at least one species of native fish.
Pressures and management responses
Pressures
Management responses
High nutrient concentrations causing excessive algal growth although the source(s) of the nutrients are not known.
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).
Walker, K.F., Puckridge, J.T. & S.J. Blanch (1997). Irrigation development on Cooper Creek, central Australia – prospects for a regulated economy in a boom-and-bust ecology. Aquatic Conservation: Marine and Freshwater EcosystemsVolume 7, pages 63-73.
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.
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Observed Condition
Expected Condition
