Eregunda Creek, Eregunda Spring
2012 Aquatic Ecosystem Condition Report
- Permanently flowing, shallow stream with riffle and pool habitats present in autumn and spring 2012
- Diverse macroinvertebrate community with several flow dependent species present
- Water was moderately fresh, clear and obviously enriched with nutrients
- Riparian vegetation consisted of native trees and shrubs
About the location
Eregunda Creek is a small stream that rises to the east from Blinman in ‘The Bunkers’, and flows eastwards where it discharges into Wirrealpa Creek and then Balcoracana Creek in the Lake Frome Basin; flow only extends downstream into Balcoracana Creek during exceptionally wet years. The only land use in the 6,041 hectare catchment, upstream from the site sampled, is grazing natural vegetation. The monitoring site was located off a track to ‘Narrina’, about 12 km east-north-east from Blinman.
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 due to nutrient enrichment and the sheep accessing the site but the creek provides permanently flowing habitat for a diverse range of aquatic species, including some sensitive and flow dependent species.
A diverse community of at least 37 species of macroinvertebrates was collected from the creek, 1.2-3.2 m wide and up to 15 cm deep, in autumn and spring 2012. The shallow creek consisted of a series of still to slow-flowing pools connected by faster-flowing riffle habitats in both seasons sampled. The community was dominated by moderate to large numbers of blackflies (Simulium ornatipes) and caddisflies (Cheumatopsyche) in the riffles and chironomids (Procladius, Paramerina, Larsia, Corynoneura, Cricotopus and Chironomus) and scirtid beetles in the pools. The community also included smaller numbers of flatworms, mites (Limnesia), beetles (Allodessus, Sternopriscus, Platynectes, Paranacaena, Enochrus, Limnoxenus and Hydrochus), mosquitoes (Anopheles and Aedes), biting midges (Nilobezzia, Forcipomyia and Dasyhelea), various other aquatic fly families (Tabanidae, Tipulidae, Stratiomyidae and Dolichopodidae), mayflies (Tasmanocoenis tillyardi and Cloeon), waterbugs (Microvelia, Enithares and Anisops), dragonflies (Hemianax, Diplacodes 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 the mite, flatworms, and several flow-dependent species (e.g. blackflies, caddisfly Cheumatopsyche, beetle Platynectes, biting midge Forcipomyia and Dolichopodidae larvae). The creek also provides habitat for both of the sensitive but commonly occurring mayflies from the region.
The water was moderately fresh (salinity ranged from 1,229-1,348 mg/L), well oxygenated (100-117% saturation), clear, and with moderate to high concentrations of nutrients such as phosphorus (0.02-0.05 mg/L) and nitrogen (0.56-0.92 mg/L).
The sediments were dominated by cobble, pebble and gravel, with filamentous algae, sand, silt and detritus also present; samples taken from below the surface were sulphidic red and grey sands, indicating that the sediments were occasionally anaerobic, or lacking in oxygen. No evidence of any significant erosion was recorded but sheep and kangaroos visited the stream during the year and defaecated along the edges of the stream.
A moderate to large amount of phytoplankton was recorded during both surveys (chlorophyll a ranged from 3.4-10.8 Âµg/L) and filamentous algae (Spirogyra and Cladophora) extended over 35% of the channel in spring 2012. Aquatic plants also extended over a similar area and included both submerged (Chara and Nitella) and emergent species (Cyperus, Juncus, Typha and introduced Rorippa). The riparian vegetation was dominated by River Red Gums and acacias over sedges, rushes and grasses on the moderately well vegetated banks (50-79% vegetative cover). The surrounding vegetation at the site comprised low native woodland dominated by gums, acacias and White Cypress Pines.
Special environmental features
Eregunda Creek is a largely natural, permanent to semi-permanent stream in the Northern Flinders Ranges that provides habitat for a wide range of aquatic macroinvertebrate species, including several flow-dependent species.
Pressures and management responses
|Livestock and feral animals (goats) have direct access at the site and upstream, exerting excessive grazing pressure, 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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