Permanent stream with flowing habitats in autumn but only isolated waterholes present in spring 2012
Diverse macroinvertebrate community with some rare and flow dependent species present
Water was moderately fresh to saline, clear and obviously enriched with nutrients in spring
Riparian vegetation consisted of native trees and shrubs
Area map
About the location
Arkaroola Creek is a large stream that rises off Mainwater Pound in the Vulkathunha-Gammon Ranges and flows south-east for about 55 km where it eventually discharges onto the plains surrounding the north-western edge of Lake Frome; flow only extends onto the plains during exceptionally wet years. The major land uses in the 24,270 hectare catchment, upstream from the site sampled, are national park (72%) and grazing natural vegetation (28%); however, the pastoral lease in the upstream catchment has not been grazed since the 1970’s. The monitoring site was located just downstream from the junction of Illinawortina and Bolla Bollana creeks at the start of Arkaroola Creek, and accessed by Umberatana Road, about 6 km north-west from Arkaroola in the Arkaroola Wildlife Sanctuary.
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 the level of nutrient enrichment and presence of weeds on the banks but the waterhole provides a significant habitat for several rare and sensitive species of macroinvertebrates and native overstorey plant assemblages.
Findings
A diverse community of at least 38 species of macroinvertebrates was collected from the creek, 2.2-6.7 m wide and up to 42 cm deep, in autumn and spring 2012. The shallow creek consisted of a series of still to slow-flowing pools connected by fast-flowing riffle habitats in autumn but it contracted to isolated, non-flowing pools in spring. The community was dominated by large numbers of baetid mayflies (Cloeon) and blackflies (Simulium ornatipes) from the autumn pool and riffle habitats, respectively, and biting midges (Bezzia) were particularly common from the pools in spring. The community also included smaller numbers of snails (Isidorella hainesii), mites (Limnesia and Unionicola), beetles (Allodessus, Hyphydrus, Sternopriscus, Necterosoma regulare, Platynectes, Eretes, Macrogyrus, Berosus australie and hydrophilid larvae), mosquitoes (Anopheles), chironomids (Procladius, Ablabesmyia, Paramerina, Larsia, Cricotopus, Tanytarsus, Kiefferulus and Chironomus), other fly larvae (Tabanidae and Stratiomyidae), caenid mayflies (Tasmanocoenis tillyardi), waterbugs (Microvelia, Agraptocorixa, Micronecta, Enithares and Anisops), dragonflies (Diplacodes and Hemicordulia) and caddisflies (Cheumatopsyche, Hellyethira simplex and Oecetis). Most species collected were mobile, tolerant and generalist insect groups but notable exceptions included the presence of a regionally rare snail and two families of mites. The site also provided habitat for several flow-dependent species (e.g. blackflies, caddisfly Cheumatopsyche and beetle Platynectes) and supported both of the sensitive but commonly occurring mayflies from the region.
The water was moderately fresh to saline (salinity ranged from 2,472-4,829 mg/L), well oxygenated (74-130% saturation), clear, and with low concentrations of nutrients in autumn but high concentrations in spring when the water had evapo-concentrated into smaller pools; phosphorus concentrations ranged from 0.02-0.05 mg/L and nitrogen ranged from 0.39-1.35 mg/L.
The sediments were dominated by filamentous algae and detritus, with bedrock, boulder, cobble, pebble, gravel, sand and silt also present; samples taken from below the surface were well aerated grey sands in autumn when the stream was flowing but they changed to sulphidic, anaerobic blackened silts in spring when the pools were drying. No evidence of any significant erosion was recorded and the only signs of animals visiting the waterhole were from the deposit of kangaroo and emu faeces around the site.
A moderate amount of phytoplankton was recorded during both surveys (chlorophyll a ranged from 2.6-9.4 µg/L) and a filamentous alga (Cladophora) extended over 65% of the waterhole. A few scattered sedges (Cyperus gymnocaulos) were the only aquatic plants recorded from the edge of the waterhole, where they covered less than 10% of the site. The riparian vegetation was dominated by River Red Gums and acacias over sedges, rushes, weeds 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, paperbarks and White Cypress Pines.
Special environmental features
Arkaroola 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 rare, sensitive and flow-dependent species in the region. Most of the upper catchment lies in the Arkaroola Wildlife Sanctuary, which is notable for its wildlife conservation values, threatened species, significant geological monuments and inclusion of various features in the Register of the National Estate.
Pressures and management responses
Pressures
Management responses
Feral goats are exerting excessive grazing pressure on vegetation, causing erosion and adding excessive nutrients to the watercourse.
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.
Observed Condition
Expected Condition
