Reedy Creek, Reedy Springs
2012 Aquatic Ecosystem Condition Report
- Permanent stream with isolated pools in autumn and spring 2012
- Moderately diverse macroinvertebrate community with two regionally sensitive mayflies collected
- Water was moderately fresh, clear and enriched with nutrients despite variable nitrogen and phosphorus concentrations
- Riparian vegetation consisted of poorly vegetated banks damaged by stock
About the location
Reedy Creek is a small stream that rises off the Loves Mine Range and The Bunkers in the Southern Flinders Ranges and flows eastwards where it discharges into Yadnapunda Creek. This stream then flows into Wilpena Creek, which discharges onto the plains surrounding the western edge of Lake Frome during exceptionally wet years. The major land uses in the 3,092 hectare catchment, upstream from the site sampled, are grazing natural vegetation (85%) and national parks (15%). The monitoring site was located off a track from Willow Springs, about 18 km east from Wilpena.
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, bank erosion and stock accessing the site but the stream still provided habitat for sensitive and commonly occurring macroinvertebrate species and several types of native aquatic plants.
A moderately diverse community of at least 24 species of macroinvertebrates was collected from the creek, 2.2-3.2 m wide and up to 26 cm deep, in autumn and spring 2012. The creek consisted of a series of isolated pools in both seasons sampled. The community was dominated by moderate to large numbers of chironomids (Procladius, Paramerina, Tanytarsus and Chironomus) and baetid mayflies (Cloeon) in autumn but only moderate numbers of unidentified mites were recorded in spring. The community also included smaller numbers of flatworms, beetles (Necterosoma, Platynectes, Rhantus and Scirtidae), mosquitoes (Anopheles), biting midges (Bezzia and Dasyhelea), soldierflies, caenid mayflies (Tasmanocoenis tillyardi), waterbugs (Microvelia, Agraptocorixa, Enithares and Anisops), dragonflies (Hemianax and Hemicordulia) and caddisflies (Hellyethira simplex and Triplectides australis). Most species collected were mobile, tolerant and generalist insect groups but notable exceptions included the presence of mites, flatworms, and the regionally sensitive but commonly occurring baetid and caenid mayflies. However, no regionally rare or specialist species were recorded, and the only indication that the stream flows occasionally was by the collection of a few adult dytiscid beetles (Platynectes) which are often found among rocks in flowing habitats.
The water was fresh to moderately fresh (salinity ranged from 799-1,175 mg/L), well oxygenated (74-85% saturation), clear, and had low nutrient concentrations in autumn but moderate to high concentrations were recorded in spring (e.g. phosphorus ranged from 0.02-0.03 mg/L and nitrogen ranged from 0.15-0.62 mg/L).
The sediments were dominated by bedrock, filamentous algae and detritus, with boulder, cobble, pebble, gravel, sand and silt also present; samples taken from below the surface were anaerobic and sulphidic sands and silts, indicating that the sediments were lacking in oxygen and a harsh environment for most burrowing species to be able to survive in. Only a light cover of biofilm and algae covered rocks in the stream but no significant build-up of silt was recorded. About 10 m of bank showed some evidence of erosion caused by stock grazing activities, and both sheep and kangaroo faeces were deposited throughout the edges of the pools and on the banks surrounding the site sampled.
A low amount of phytoplankton was recorded during both surveys (chlorophyll a ranged from 1.2-2 Âµg/L) but filamentous algae (Spirogyra and Cladophora) covered over 35% of the channel in 2012. Aquatic plants also extended over a similar area in autumn but were slightly less prevalent in the follow-up spring survey. The range of plants recorded included both submerged (Chara) and emergent species (Cyperus, Typha, Cotula, Isolepis and introduced Rorippa). The riparian vegetation was dominated by patches of gums and acacias over sedges and grasses on the poorly vegetated banks (25-49% vegetative cover). The surrounding vegetation at the site comprised low native woodland dominated by White Cypress Pines and acacias and over native shrubs and grasses.
Special environmental features
Reedy Creek is a largely natural, permanent to semi-permanent stream in the Southern Flinders Ranges that provides habitat for a wide range of aquatic macroinvertebrate species, including baetid and caenid mayflies and many generalist types of aquatic insects. However, no significant environmental features were noted from the site based on the aquatic life recorded in 2012.
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 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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