Blackfellows Creek, near Mount Magnificent Conservation Park
2010 Aquatic Ecosystem Condition Report
- Slow-flowing, freshwater creek in autumn and spring.
- Sparse macroinvertebrate community with several rare and sensitive species.
- Obvious signs of moderate nutrient enrichment.
- Riparian vegetation was mostly woody weeds and native shrubs and trees.
About the location
Blackfellow Creek is a small stream in the southern Mount Lofty Ranges. It rises east of Kuitpo and drains in a southwesterly direction where it eventually discharges into the Finniss River to the east of Yundi. The major land use is native vegetation, with forestry and grazing dominating further upstream. The monitoring site was located at the southern end of Blackfellows Creek Road, about 10 km north-east of Yundi.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was some evidence of human disturbance of the site, including nutrient enrichment, weed invasion of the riparian zone and bank erosion which could result in the condition of this stream being downgraded to a Fair or Poor rating in future years.
A sparse community of about 26 species of macroinvertebrates was collected from this slow-flowing creek, three metres wide and 55 cm deep, in spring. Water was also present in autumn, however, the blackberry bushes were too thick to allow access to sample the creek. The macroinvertebrate community was dominated by leptophlebiid mayflies (including Koorrnonga inconspicua) and chironomids. It also included smaller numbers of snails (including the introduced Potamopyrgus antipodarum), mites, amphipods, beetles, mosquitoes, biting midges, waterbugs, dragonflies and caddisflies.
Several rare and sensitive species were recorded, including the leptophlebiid mayfly, gripopterygid stonefly (Illiesoperla mayi) and blackfly (Austrosimulium furiosum). The only fish collected from the site was the threatened Mountain Galaxias (Galaxias olidus).
The water was fresh (salinity of 447 mg/L), well oxygenated (90% saturation), clear but strongly coloured, with moderate to high concentrations of nutrients such as nitrogen (0.67 mg/L) and phosphorus (0.04 mg/L).
The sediments were dominated by detritus, gravel, sand and clay; samples taken from below the surface showed no indications that the sediment was lacking in oxygen. More than 10 metres of the bank showed signs of erosion due to past flood damage.
No filamentous algae was seen at the site but a large amount of phytoplankton was present. More than 35% of the site was covered in aquatic plants that included several submerged (Callitriche) and emergent species (Phragmites, Isolepis, Polygonum, Cyperus, Juncus and Triglochin). The riparian zone consisted of dense growths of blackberries and Common Reed (Phragmites), as well as weeds, bracken and introduced grasses, under a canopy of large gum trees and native shrubs. The surrounding vegetation at the site was native woodland and forest.
Special enironmental features
Blackfellow Creek provides habitat for several significant species of macroinvertebrates and a threatened native fish (Mountain Galaxias).
Pressures and management responses
|Extensive weed growth in the riparian zone at the site and upstream in the catchment (causing habitat disturbance).||The SA Murray-Darling Basin NRM Board recognises the limitations of available funds relative to the scale of the degradation caused by introduced trees and weeds. The NRM Board provides free technical advice and community education to assist land managers in dealing with the integrated management of aquatic weeds. The NRM Board also has a targeted process, as directed by State Government, to strictly prioritise its investment in weed control activities as funds are limited. The NRM Board actively seeks funding opportunities for weed control; most opportunities are for locations where biodiversity outcomes can be achieved.|
|Limited riparian vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The SA Murray-Darling Basin NRM Board recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.|