Riparian vegetation consisted of native trees and shrubs over weeds, and one native aquatic plant occurred in the waterhole
Area map
About the location
Diamantina River is a large stream that rises at an altitude of nearly 500m in central west Queensland and flows south-westerly for about 900 km through central Queensland and the ‘channel country’ to form the Warburton River at its confluence with the Georgina River, downstream from Goyder Lagoon in South Australia. For much of its length, the Diamantina River has no main channel but consists of a series of wide, relatively shallow channels and associated floodplain habitats. Soils in the catchment are dominated by grey and brown clays that are generally low in phosphate but rich enough to support abundant growths of grasses whenever rains occur.
Flow patterns in the unregulated Diamantina River are highly variable and driven by monsoonal summer rainfall in the upper catchment area of Queensland. The Diamantina River and Cooper Creek are the world’s most variable major rivers in the world, characterised by ‘boom’ (major floods) and ‘bust’ (major dry periods and drought). In extremely wet years when rainfall reaches around 500mm year across much of its catchment, 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 waterholes occur throughout each river system (for more details see Silcock 2009).
The major land uses in the 157,000 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 the Diamantina National Park near Winton.
The monitoring site was located on a track off the Birdsville Track to Pandie Pandie station, in northern South Australia about 30 km south from Birdsville.
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 including nutrient enrichment and weedy riparian zones but the stream provides habitat for a range of aquatic macroinvertebrates, including several rare species. 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.
Findings
A moderately diverse community of at least 16 species of macroinvertebrates was collected from the 40 m wide, non-flowing, arid-zone waterhole in spring 2012. The community was dominated by low to moderate numbers of waterbugs (Micronecta and Anisops species) but included smaller numbers of 5 types of beetles (Hydraena, Enochrus, Sternopriscus maedfooti, Platynectes and Staphylinidae), 4 chironomids (Coelopynia, Harnischia, Cricotopus and Tanytarsus), 2 mites (Unionicolidae and Koenikea), and a freshwater prawn (Macrobrachium), a springtail and a biting midge (Ceratopogonidae). The total number of species is likely to be closer to around 20 species since a caenid mayfly pupal case was collected, yabby holes were recorded, and a snail egg mass and 1 cm mussel shell (presumably Corbiculina) were also noted from the site. The rich assemblage of tolerant insect groups such as beetles, chironomids and waterbugs were similar to those found in other waterholes in the region. The prawn was the only species recorded that is normally associated with stream environments. The only rarely collected species were the two mite families and two chironomids (Coelopynia and Harnischia). No fish were caught or seen at the site when it was sampled in October 2012.
The water was fresh (salinity of about 126 mg/L), well oxygenated (88% saturated) and very turbid (secchi depth 4 cm), with high concentrations of nutrients such as nitrogen (2.8 mg/L) and phosphorus (0.69 mg/L).
The sediments were dominated by clay, with smaller amounts of detritus, silt, sand, gravel and algae; samples taken from below the surface were grey clays and silts and showed no signs that the sediments were anaerobic, or lacking in oxygen. About 10 m of the banks showed evidence of erosion due to cattle and flood damage. Cattle graze on the steep banks surrounding this waterhole and their faeces were observed throughout the site.
A moderate amount of phytoplankton was present (chlorophyll a 3.5 µg/L) and green filamentous alga (Cladophora) covered about 10% of the waterhole. A similar area was covered by an emergent, native aquatic plant called Water Primrose (Ludwigia peploides). The riparian vegetation was dominated by lignum and gums over various weeds on the moderately vegetated banks (50-79% vegetative cover). The surrounding vegetation comprised scattered gum trees and weeds.
Special environmental features
Diamantina River at Pandie Pandie provides habitat for large numbers of birds, acting as a refuge in an arid landscape. Cormorants, egrets, swallows and kites were seen when the waterhole was sampled in spring 2012. The waterhole was also sampled specifically for fish using a range of nets in May 2012 as part of the Lake Eyre Basin Rivers Assessment (Cockayne et al. 2013). The waterhole actually provides an important permanent refuge habitat for at least 9 native species, including large numbers of Lake Eyre Golden Perch and smaller numbers of Desert Glassfish, Bony Bream, Desert Rainbowfish, Welch’s Grunter, Spangled Perch, Hyrtl’s Catfish, Silver Tandan and Barcoo Grunter.
Pressures and management responses
Pressures
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).
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.
Observed Condition
Expected Condition
