Riparian vegetation consisted of native trees and shrubs over weeds and a large amount of filamentous algae and one aquatic plant were recorded from 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 the track off the Birdsville Track to Clifton Hills Outstation, towards the northern part of Goyder Lagoon in northern South Australia and about 87 km south from Birdsville.
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. There was evidence of human disturbance including nutrient enrichment, stock accessing the banks and weedy riparian zones 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.
Findings
A diverse community of at least 28 species of macroinvertebrates was collected from the 50 m wide, non-flowing, arid-zone waterhole in spring 2012. The community was dominated by low to moderate numbers of freshwater prawn (Macrobrachium) but included 11 types of beetles (Sternopriscus maedfooti, Allodessus, Rhantus, Laccophilus, Ochthebius, Hydraena, Spercheus, Enochrus, Helochares and a specimen from each of the families Staphylinidae and Carabidae), 5 waterbugs (Anisops hyperion, Microvelia oceanica, Micronecta robusta, Sigara truncatipala and Naucoris), 3 chironomids (Coelopynia, Cricotopus and a specimen from the sub-family Chironominae), 2 mayflies (Cloeon and Tasmanocoenis arcuata), 2 molluscs (limpet Ferrissia and snail Glyptophysa aliciae), a mite (Unionicolidae), marsh fly (Sciomyzidae), odonate (Austrogomphus australis) and a caddisfly (Triplectides australis). The total number of species is likely to be closer to 30 since yabby holes were recorded in the banks and mussel shells have been recorded from other nearby sites in the catchment. The rich assemblage of tolerant, aerially dispersed insect groups such as beetles, waterbugs and flies were similar to those found in other waterholes in the region. The prawn and mayfly (T. arcuata) were the only species recorded that are normally associated with stream environments. The only rarely collected macroinvertebrates recorded were the mite, chironomid (Coelopynia), caenid mayfly (T. arcuata), dytiscid beetle (Laccophilus) and odonate (Austrogomphus), although several of the other beetles and molluscs could also be highlighted as rare or uncommon in the region. The mayflies are sensitive species that are widely distributed from the more permanent freshwater habitats in the region.
An unusually complex range of trophic feeding strategies for the region was represented by the species collected (e.g. omnivores, herbivores, detritivores and predatory beetles) and is probably a nutrient enrichment response by the aquatic macroinvertebrates inhabiting the local area near this waterhole.
No fish were caught or seen at the site when it was sampled in October 2012.
The water was fresh (salinity of about 205 mg/L), well oxygenated (74% saturated) and very turbid (secchi depth 3 cm), with high concentrations of nutrients such as nitrogen (3.69 mg/L) and phosphorus (1.02 mg/L).
The sediments were dominated by detritus with smaller amounts of silt, clay, sand 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 bank showed evidence of erosion caused by cattle damage and cattle faeces were found throughout the site.
A large amount of phytoplankton was present (chlorophyll a 15.6 µg/L) and included some blue-green algae or cyanobacteria (chlorophyll b 2.6 µg/L). Green filamentous algae (Cladophora and Spirogyra) covered over 65% of the edge of the waterhole, and patches of an emergent aquatic plant called Water Primrose (Ludwigia peploides) extended over more than 10% of the site. The riparian vegetation was dominated by gums, acacias and lignum over various weeds on the moderately vegetated banks (50-79% vegetative cover). The surrounding floodplain vegetation comprised scattered gum trees, saltbush and weeds.
Special environmental features
The more permanent waterholes and channel reaches on the Diamantina River 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 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).
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.
Excessive weed growth in the riparian zone
The SA Arid Lands Natural Resources Management Board provides technical advice and incentives for the management of introduced weeds and feral pest animals, as funding permits. Pest management efforts are guided by a region-wide strategy, based on risk assessment, to determine priority locations and species. Funding is actively sought from a number of sources to support region-wide integrated management.
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
