Mount Chambers Creek, Mt Chambers Gorge
2012 Aquatic Ecosystem Condition Report
- Permanent, shallow flowing stream in autumn but comprised pool habitats connected by slightly flowing riffles in spring 2012
- Diverse macroinvertebrate community with several flow-dependent species present
- Water was saline, clear and generally low in nutrient concentrations despite showing signs of significant nutrient enrichment
- Riparian vegetation consisted of native trees and shrubs and the creek was covered by filamentous algae and aquatic plants
About the location
Mount Chambers Creek is a large stream that rises west from Mount John in the Northern Flinders Ranges and flows east for about 46 km where it eventually discharges into the western side of Lake Frome; flow only extends onto the surrounding plains and lake during exceptionally wet years. The major land uses in the 42,298 hectare catchment, upstream from the site sampled, were grazing natural vegetation (90.5%) and traditional indigenous uses associated with the Nantawarrina Indigenous Protected Area (9.5%). The monitoring site was located off a track to Mt Chambers Gorge from the Blinman to Balcanoona Rd, about 55 km east-north-east from Blinman.
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. Therewas evidence of human disturbance due to extensive nutrient enrichment presumably sourced from catchment grazing but the stream still provided habitat for a diverse community of aquatic macroinvertebrates and plants.
A diverse community of at least 33 species of macroinvertebrates was collected from the creek, 2.1-4 m wide and up to 30 cm deep, in autumn and spring 2012. The creek consisted of similar areas of slow-flowing pools connected by faster-flowing riffle habitats in autumn but contracted to smaller, deeper pools connected by slightly flowing seeps in spring. The community was dominated by large numbers of blackflies (Simulium ornatipes) and caddisflies (Cheumatopsyche) in the riffles and more moderate numbers of biting midges (Bezzia, Forcipomyia and Dasyhelea), chironomids (Procladius, Cricotopus, Tanytarsus, Chironomus, Kiefferulus and Polypedilum) and baetid mayflies (Cloeon) in the pools. The community also included smaller numbers of dytiscid beetles (Allodessus, Necterosoma penicillatus, Eretes and Platynectes), hydrophilid beetles (Paracymus), mosquitoes (Anopheles), flies (tabanids, stratiomyids and ephydrids), waterbugs (Hydrometra, Microvelia, Agraptocorixa, Enithares and Anisops), odonates (Ischnura, Hemianax, Diplacodes and Orthetrum) and caddisflies (Hellyethira simplex and Triplectides australis). A number of flow-dependent species (Simulium, Cheumatopsyche and Platynectes) and uncommon species for the region (Kiefferulus and Hydrometra) were collected from the site. The mayfly was the only sensitive but widely distributed species collected. Most species were, however, generalist and tolerant insect species and the lack of snails and other molluscs, mites and crustaceans indicates that the stream may dry on occasions for extended periods.
The water was saline (salinity ranged from 3,446-6,668 mg/L), well oxygenated (118-162% saturation), clear, and with low concentrations of nutrients in autumn when the stream was flowing strongly but higher concentrations in spring when flowing habitats were more limited; phosphorus concentrations ranged from 0.03-0.04 mg/L and nitrogen ranged from 0.15-0.79 mg/L.
The sediments were dominated by algae, with smaller amounts of sand, gravel, bedrock, boulder, cobble, pebble and detritus also present; samples taken from below the surface were well-aerated gravels in autumn but changed to anaerobic, sulphidic black silts in spring, indicating that they became anaerobic, or lacking in oxygen, when flows reduced and large amounts of organic material were being decomposed by microbial processes during the warmer months. No evidence of any significant bank erosion or deposits of animal faeces were recorded from the margins of this rocky stream.
A moderate amount of phytoplankton was present in spring (chlorophyll a 4.8 Âµg/L) and over 65% of the shallow margins of the creek was covered by filamentous algae (Cladophora, Spirogyra and Enteromorpha). Aquatic plants covered more than 10% of the channel and included submerged (Chara) and emergent species (Cyperus, Typha and Juncus). The riparian vegetation was dominated by River Red Gums, paperbarks and wattles over sedges and grasses on the moderately well vegetated banks (50-79% vegetative cover). The creek was located within a gorge so the riparian vegetation extended to the start of the cliffs.
Special environmental features
Mount Chambers Creek is a largely natural, permanent, saline stream in the North Flinders Ranges that provides habitat for a wide range of aquatic insect species, including several flow-dependent species and a few uncommonly collected and sensitive species from the region.
Pressures and management responses
|Feral goats and donkeys 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.|