Yardaparinna Creek, Macumba
2012 Aquatic Ecosystem Condition Report
- Semi-permanent, non-flowing waterhole when sampled in autumn 2012
- Diverse macroinvertebrate community with several regionally rare and sensitive species collected
- Water was fresh, clear and enriched with nutrients
- Riparian vegetation consisted of native trees and shrubs and two aquatic plants
About the location
Yardaparinna Creek is a small ephemeral stream that rises north-east from Oodnadatta in the Far North of the State and flows in a northerly direction for about 40 km, before discharging into Macumba River during exceptionally wet years. The Macumba River eventually discharges into the northern part of Lake Eyre North, also only during very wet years. The major land use in the catchment is cattle grazing. The monitoring site was located off an unnamed track, a couple of kilometres north from Macumba Homestead and about 40 km north-north-east from Oodnadatta.
The creek was given a Very Good rating because the site sampled showed evidence of very little changes in ecosystem structure and function, with many rare and sensitive aquatic macroinvertebrates present. There was some minor evidence of human disturbance at the site, including nutrient enrichment, bank erosion and cattle accessing the banks but the stream still provided an important refuge for many macroinvertebrate species from the region.
A diverse community of at least 29 species of macroinvertebrates was collected from the isolated waterhole, 120 m long x 15 m wide and less than 25 cm deep, in autumn 2012. The community was dominated by large numbers of waterbugs (Micronecta and Agraptocorixa parvipunctata) and included smaller numbers of mayflies (Cloeon and Tasmanocoenis tillyardi), mites (Eylais), chironomids (Coelopynia, Paraborniella, Tanytarsus, Dicrotendipes, Ablabesmyia, Polypedilum, Larsia and Procladius), caddisflies (Triplectides australis, Oecetis and Ecnomus cygnitus), beetles (Berosus nutans, Berosus discolour, Necterosoma dispar, Allodessus and Hyphydrus), waterbugs (Anisops thienemanni), hydrozoans (Hydra), freshwater prawns (Macrobrachium), biting midges (Culicoides), mosquitoes (Anopheles), coenagrionid damselflies and dragonflies (Hemicordulia tau and Orthetrum). It included many regionally rare and sensitive species including midges (Coelopynia, Paraborniella and Larsia), the hydrozoan, caddisfly Oecetis, beetle (Necterosoma dispar) and both mayflies. The community also included a rich range of waterbugs, beetles, chironomids and caddisflies, along with a riverine species (prawn) and long-lived dragonfly (Hemicordulia). The presence of Hydra, the mite and prawn among such a diverse insect community indicates that the waterhole probably remains wet most of the time and would rarely dry for extended periods of time. Only a small number of zooplankters were recorded from the site, which included copepods, ostracods and cladocerans. Hardyheads were the only fish recorded from the site.
The water was very fresh (salinity of 116 mg/L), well oxygenated (106% saturation), clear, and with moderate to high concentrations of nutrients such as nitrogen (1.3 mg/L) and phosphorus (0.08 mg/L).
The sediments were dominated by sand, detritus and clay, with smaller amounts of cobble, silt and algae also present; samples taken from below the surface were sulfidic grey sands which indicate that the sediments were anaerobic, or lacking in oxygen. Over 10% of the site showed evidence of bank erosion which was probably caused by cattle accessing the edges of the waterhole.
A low to moderate amount of phytoplankton was present (chlorophyll a 5.8 Âµg/L) but only a negligible amount of blue-green algae or cyanobacteria was detected. About 10% of the shallow margins of the waterhole were covered by a filamentous alga (Cladophora) and a similar area was also covered by aquatic plants (submerged Myriophyllum and emergent Cyperus). The riparian vegetation was dominated by gum trees and acacias over sedges on the poorly vegetated banks (25-49% vegetative cover). The surrounding vegetation at the site comprised scattered native woodland and grasses.
Special environmental features
Yardaparinna Creek provides habitat for the most diverse community of aquatic macroinvertebrates recorded from the region in autumn 2012. It also includes a rich plant assemblage and supports at least one species of native fish. Consequently, the site provides a significant aquatic refuge habitat for the Macumba River catchment and the Lake Eyre Basin.
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 excessive 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.|
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