Riparian vegetation consisted of native trees and shrubs but no aquatic plants were recorded
Area map
About the location
Cooper Creek is a large stream in the Far North that rises at an altitude of 230m 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 (Qld only) 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 in the Innamincka Regional Reserve off the Coongie Track, about 37 km west from Innamincka.
In summary
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 due to nutrient enrichment and stock access but the stream provides habitat for a range of aquatic species, including rare and sensitive species of macroinvertebrates. 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 diverse community of at least 23 species of macroinvertebrates was collected from the 19 m wide, non-flowing, arid-zone waterhole in spring 2012. The community was dominated by moderate numbers of waterbugs (Micronecta and Anisops species) but included smaller numbers of 7 types of beetles (Hydraena, Ochthebius, Enochrus, Liodessus, Sternopriscus multimaculatus, Eretes australis and Megaporus), 4 chironomids (Polypedilum, Cryptochironomus, Procladius and Paramerina), 3 waterbugs (Nepidae, Agraptocorixa and Microvelia oceanica), 2 molluscs (Thiaridae and Corbiculina), and one species of mosquito (Anopheles), mayfly (Cloeon), biting midge (Nilobezzia) and a freshwater prawn (Macrobrachium). Several mussel shells (Velesunio) were also seen around the edge of the waterhole. The site supported a rich assemblage of beetles, chironomids and waterbugs but the absence of odonates, caddisflies and mites was unexpected given the range of habitat types present. The only groups normally associated with stream environments were the prawn and thiarid snail, whereas the other species are typically found in pool habitats and temporary waters throughout the Far North region. The only rare species collected were the thiarid snail and the nepid waterbug. The baetid mayfly was the only sensitive group recorded which typically occurs from the more permanent freshwater habitats in the region. No fish were caught or seen at the site when it was sampled in November 2012.
The water was fresh (salinity of about 177 mg/L), well oxygenated (103% saturated) and turbid (secchi depth 9 cm), with high concentrations of nutrients such as nitrogen (1.72 mg/L) and phosphorus (0.44 mg/L).
The sediments were dominated by sand and detritus, with smaller amounts of silt, clay and algae; samples taken from below the surface were sandy in composition and showed no signs that the sediments were anaerobic, or lacking in oxygen. No evidence of any significant bank erosion was noted but large amounts of cattle faeces were recorded from the edge and banks surrounding the waterhole.
A moderate amount of phytoplankton was present (chlorophyll a 8.8 µg/L) and a small amount of filamentous algae was also recorded. No aquatic plants were seen. The riparian vegetation was dominated by gum trees, acacias and lignum and the banks were only poorly to moderately vegetated (25-49% vegetative cover). The surrounding vegetation comprised low gum and acacia woodland.
Special environmental features
The more permanent waterholes and channel reaches on Cooper Creek provide an important refuge habitat for a wide range of arid-zone fish (Cockayne et al. 2013). While no fish were noted during the present work, the waterhole probably supports a number of fish species for extended periods following flood events.
Pressures and management responses
Pressures
Management responses
High nutrient concentrations causing excessive algal growth although the source(s) of the nutrients are 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)
Livestock have direct access at the site and upstream in the catchment exerting excessive grazing pressure on vegetation, causing sediment erosion and adding 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.
Cockayne, B., Schmarr, D., Duguid, A. & R. Mathwin (2013). “Lake Eyre Basin Rivers Assessment (LEBRA) 2012 Monitoring Report.” Report to LEBRA Oversight Group.
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.
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 Ecosystems, Volume 7, pages 63-73.
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Observed Condition
Expected Condition
