Kanyaka Creek, Kanyaka Gauge Station
2012 Aquatic Ecosystem Condition Report
- Permanent, shallow flowing stream in autumn and spring 2012
- Diverse macroinvertebrate community with two species of mayflies and several flow-dependent species collected
- Water was moderately fresh to saline, generally clear and moderately enriched with nutrients
- Riparian vegetation consisted of a sparse cover of native trees and shrubs and only a few aquatic plants and filamentous algae were recorded
About the location
Kanyaka Creek rises near Hawker and initially flows southwards for several kilometres before turning west near Gordon, and flowing for several more kilometres until it discharges into Willochra Creek, about 5 km north from Simmonston. During exceptionally wet years the Willochra Creek flows into the southern part of Lake Torrens in the Southern Flinders Ranges. The major land uses in the 18,754 hectare catchment, upstream from the site sampled, are grazing modified pastures (84%) and grazing natural vegetation (15%). The monitoring site was located off a track from Barndioota Road (e.g. Leigh Creek Road) near the Kanyaka ruin, about 3 km north-east from Gordon and 26 km south-west from Hawker.
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, bank erosion due to stock access and the presence of weeds in the riparian zones but the stream still provides habitat for a wide range of aquatic macroinvertebrates and at least two aquatic plants.
A diverse community of at least 36 species of macroinvertebrates was collected from the creek, 12.6-13.1 m wide and up to 38 cm deep, in autumn and spring 2012. The creek consisted of shallow pools connected by small areas of faster-flowing riffle habitats in both seasons sampled. The community was dominated by moderate numbers of corixids (Micronecta and Agraptocorixa) and baetid mayflies (Cloeon). It also included smaller numbers of mites (Eylais, Koenikea and Arrenurus), yabbies (Cherax destructor), beetles (Necterosoma, Eretes, Macrogyrus, Spercheus, Hydraena, Ochthebius and Scirtidae), mosquitoes (Anopheles), biting midges (Bezzia, Culicoides and Nilobezzia), chironomids (Procladius, Cladotanytarsus, Tanytarsus, Chironomus and Dicrotendipes), caenid mayflies (Tasmanocoenis tillyardi), waterbugs (Microvelia, Hydrometra, Enithares and Anisops), odonates (Ischnura, Austrolestes analis, Hemianax papuensis, Orthetrum caledonicum and Hemicordulia tau) and caddisflies (Triplectides australis). Large numbers of zooplankton were also recorded in spring, comprising mostly ostracods and copepods. The small riffle habitats supported several flow-dependent species, including blackflies (Simulium ornatipes), caddisflies (Cheumatopsyche), dytiscid beetles (Platynectes larvae) and tabanid larvae. The site was notable because it provided habitat for several species of mites, beetles, biting midges, chironomids, odonates and waterbugs. It was also unusual because at least three species of the back-swimmer Anisops (A. thienemanni, A. deanei and A. stali) and two species of corixid waterbug Agraptocorixa (A. eurynome and A. parvipunctata) were recorded during the two sampling periods. The lack of snails and amphipod crustaceans from the site was unexpected given the diversity of habitats present but otherwise the assemblage of species comprised most of the widely distributed, generalist insects, mites and yabbies found in the region. The riffle habitats also included the more tolerant insect groups found from flowing habitats in the northern parts of the State. However, none of the rare or highly sensitive species were recorded apart from the two commonly occurring mayflies from the region, which are probably sensitive to some types of disturbance but able to tolerate the salinity of this slightly flowing creek in the Willochra catchment. The only other aquatic species seen was a Short-necked Tortoise but no fish or frogs were seen at the site in 2012.
The water was moderately fresh to saline (salinity ranged from 2,420-4,037 mg/L), well oxygenated (93-104% saturation) clear in autumn but slightly coloured and turbid in spring, and with moderate to high concentrations of nutrients such as phosphorus (0.02-0.03 mg/L) and nitrogen (0.28-1.01 mg/L).
The sediments were dominated by detritus, silt and bedrock, with smaller amounts of cobble, pebble, filamentous algae and sand also present; samples taken from below the surface were well-aerated grey sands in autumn but they were largely sulphidic grey-black silts in spring, indicating that the sediments became anaerobic, or lacking in oxygen, during the warmer months of the year. About 10 m of the banks at the site showed evidence of erosion caused by sheep accessing the stream.
Only a small amount of phytoplankton was present in autumn but a larger amount was recorded in spring (chlorophyll a ranged from 0.7-4.8 Âµg/L) when a type of filamentous alga (Spirogyra) covered about 10% of the site. A similar area was also covered by two types of aquatic plants (sedge Cyperus gymnocaulos and rush Juncus species). The riparian vegetation was dominated by gums and acacias over sedges, rushes, chenopod shrubs and introduced grasses on the poorly vegetated banks (25-49% vegetative cover). The surrounding vegetation at the site was low saltbush country with a few scattered gums that was being grazed by sheep.
Special environmental values
Kanyaka Creek is a largely natural, permanent stream in the Southern Flinders Ranges that provides habitat for a wide range of aquatic macroinvertebrate species, including two commonly found mayflies and several of the more tolerant flow-dependent species found in the region.
Pressures and management responses
|Livestock have direct access at the site and upstream exerting excessive grazing pressure on vegetation, causing sediment erosion and adding excessive nutrients to the watercourse.||
The Northern and Yorke Regional NRM Plan has the following Resource Condition Targets:
Natural Resources (Northern and Yorke) has also been updating its understanding and management of the Willochra Catchment: