Riparian vegetation dominated by gums and pine trees over blackberries and daisies
Area map
About the location
Blackfellow Creek is a small stream in the southern Mount Lofty Ranges. It rises east from Kuitpo and drains in a southwesterly direction where it eventually discharges into the Finniss River to the east of Yundi. The major land uses are native vegetation, forestry and cattle grazing. The monitoring site was located off a private track from Woodgate Hill Road, about 6.5 kilometers west from Ashbourne and 7 kilometers south from Kuitpo Forest Headquarters in the Kuitpo Forest.
The river 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 including minor nutrient enrichment, fine sediment deposition and weeds dominating the understorey vegetation on the banks but the stream still provided habitat for a few sensitive and flow-dependent macroinvertebrates.
Findings
A moderately diverse community of at least 38 species of macroinvertebrates (21 in autumn and 23 in spring) was collected or seen from the creek, 0.5-1.9 metres wide and up to 34 centimetres deep, in autumn and spring 2015. The creek consisted of a slow to non-flowing series of pools connected by tiny areas of moderately flowing riffle habitat in autumn and shallow, isolated, drying pools in spring. The community was dominated by generalists and species tolerant to poor water quality such as chironomids (including Tanytarsus, Cricotopus and Chironomus) and scirtid beetles in autumn and amphipods (Austrochiltonia) and chironomids in spring. It also included smaller numbers of worms, water mites (Eylais, Piona, Diplodontus and Limnesia), native snails (Glyptophysa), springtails, beetles, waterbugs, biting midges, mayflies (Thraulophlebia), blackflies, stoneflies (Austrocerca and small gripopterygids), mosquitoes (Anopheles, Aedes and Culex) and caddisflies (Lectrides). The presence of yabby holes in the banks also indicated that they were a common inhabitant of the creek. The only flow-dependent and/or sensitive species recorded from the site were the blackfly, mayfly and the two stoneflies.
The water was fresh (salinity ranged from 1,129-1,363 mg/L), moderately to well oxygenated (48-80% saturated), clear and slightly turbid, and with moderate to high concentrations of nutrients such as nitrogen (0.82-0.9 mg/L) and phosphorus (0.02-0.08 mg/L).
The sediments were dominated by detritus and silt, with smaller areas of filamentous algae, sand, clay, boulder and gravel also present. The riffles also included coarser sediments such as cobbles and pebbles. Samples taken from below the surface were grey in colour and showed no evidence that the sediments had recently been anaerobic, although the blackened underside of rocks indicates that the sediments had lacked oxygen sometime in the past. Over 1 centimetres of silt covered the bottom of the creek and more than 10% of the banks showed signs of erosion due to cattle damage. Cattle and kangaroo droppings were recorded from the banks of the stream.
Only a small amount of phytoplankton (chlorophyll a 1.6-3.6 µg/L) was recorded but more than 10% of the channel was covered by a filamentous alga (Spirogyra) in autumn and spring. A similar area was covered by a range of submerged (Callitriche) and emergent aquatic plants (Cyperus, Isolepis, Persicaria and introduced Rorippa, Rumex and Ranunculus). The surrounding vegetation at the site was dense woodland on one bank and more open woodland over a weedy understorey on the other bank.
Special environmental values
Blackfellow Creek provides habitat for at least one flow-dependent blackfly, and three sensitive mayfly and stonefly species, as well as a number of generalist and tolerant macroinvertebrates and plants commonly found from streams in the region.
Mountain galaxias, a native fish species identified as vulnerable in the 2009 ‘Action plan for South Australian freshwater fishes’, has been found downstream of this site in Blackfellow Creek within the last five years (Michael Hammer, Aquasave Consultants, pers. comm.).
Pressures and management responses
Pressures
Management responses
Livestock have direct access to some creeks, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).
Natural Resources SA Murray–Darling Basin acknowledges the significant impacts that livestock have on aquatic environments and seeks to provide free technical advice and incentives to land managers for fencing and other works as funding permits. Funding incentives are limited in value and extent and require land managers to volunteer to be involved.
Limited riparian vegetation at some creeks, providing minimal buffer protection from catchment landuses (reducing habitat quality).
Natural Resources SA Murray–Darling Basin recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The NRM Board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.
Insufficient natural water flows resulting from water extraction and climate variability (reducing ecological integrity).
A water allocation plan that guides sustainable water use in the Eastern Mount Lofty Ranges has been developed by Natural Resources SA Murray–Darling Basin, working with the community and government (particularly the Department for Environment, Water and Natural Resources (DEWNR)). The plan aims to balance social, economic and environmental water needs and is implemented through a system of water licensing and permits for water affecting activities administered by DEWNR.
A key component of the water allocation plan is to provide water to sustain the environment at an acceptable level of risk. Securing low flows for the environment is a key environmental water provision in this area, and Natural Resources SA Murray–Darling Basin is working together with DEWNR, Natural Resources Adelaide and Mount Lofty Ranges and the community to develop a program to secure low flows across the Mount Lofty Ranges. For more information on water allocation planning and associated projects go to our Water Allocation Planning web page.
Widespread introduced trees and weeds in riparian zones (reducing habitat quality).
Natural Resources SA Murray–Darling Basin recognises the limitations of available funds relative to the scale of the degradation caused by introduced trees and weeds. It 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. It actively seeks funding opportunities for weed control; most opportunities are for locations where biodiversity outcomes can be achieved.