Riparian vegetation mostly comprised reeds, River Red Gums, lignum and introduced grasses
Area map
About the location
Mount Barker Creek is a moderate sized stream in the southern Mount Lofty Ranges that rises east of Echunga, flows in an easterly direction through the township of Mount Barker, and eventually discharges into the Bremer River near Callington. The major land uses are sheep and cattle grazing, dryland cropping, and both rural and urban residential living. The monitoring site was located at the downstream extent of the creek just off Callington Road, Salem, about 3 kilometres south-west from Callington.
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. There was evidence of human disturbance including moderate nutrient enrichment and degraded riparian and terrestrial habitats but the site still supported a range of rare, common and tolerant macroinvertebrates.
Findings
A sparse community of about 24 species of macroinvertebrates (13 in autumn and 17 in spring) was collected or seen from the barely flowing creek, 15-25 metres wide and over 1 metre deep in places, in autumn and spring 2015. The community was dominated by moderate numbers of tolerant, generalist species such as amphipods (Austrochiltonia and Corophiidae), freshwater shrimp (Paratya) and waterbugs (Micronecta). It also included low numbers of snails, freshwater limpets, worms, aquatic sowbugs (Heterias), water mites (Coaustraliobates, Hydroma, Limnesia and Piona), gyrinid beetles (Macrogyrus), elmid beetles (Coxelmis v. fasciatus), mayflies (Cloeon), biting midges, damselflies (Ischnura and Xanthagrion) and caddisflies (Triplectides australicus, Triplectides australis and Hellyethira). The presence of active yabby holes indicates they were also common inhabitants at the site. The only sensitive species collected was the elmid beetle, which has rarely been collected from the region in the past. The deep pool habitats and presence of introduced fish such as mosquitofish and carp seen during each survey, limits the likelihood that a rich assemblage of aquatic macroinvertebrates would be able to colonise and use the lower reaches of Mount Barker Creek as a significant habitat in the region.
The water was fresh to moderately fresh (salinity of 1,202 mg/L in autumn and 1,226 mg/L in spring), generally well oxygenated only in autumn (36-81% saturation), clear, and with moderate to high concentrations of nutrients such as nitrogen (0.60-1.14 mg/L) and phosphorus (0.05-0.06 mg/L).
The sediments were dominated by living and dead detritus, and included smaller amounts of bedrock, sand, silt and clay. Samples taken from below the surface were grey silt and clay that only released sulfide when tested in spring, indicating that the sediments were anaerobic of lacking oxygen for only part of the year. There was no evidence of any stream bank erosion or stock accessing the site during 2015.
A moderate to large amount of phytoplankton (chlorophyll a ranged from 3.6-12.4 µg/L) was recorded, particularly in autumn, but there was no sign of any filamentous algae noted during either survey conducted at the site. Over 35% of the site was also covered by emergent aquatic plants, including dense stands of reeds (Phragmites) and patches of cumbungi (Typha). The narrow, <5 metres wide riparian zone consisted mainly of reeds, introduced grasses, lignum and prickly acacias under large River Red Gums. The surrounding vegetation was mostly cleared land that is currently being rehabilitated and revegetated with native trees and understorey plants; further downstream, cleared grazing and cropping land dominate the local landscape.
Special environmental values
The most notable feature of the site was the presence of the rarely collected water beetle and the rehabilitation works that have been implemented in recent years. Further upstream, Mount Barker Creek provides habitat for at least two sensitive types of macroinvertebrates commonly associated with flowing water, the mayfly (Atalophlebia) and gripopterygid stoneflies.
Congolli and Mountain Galaxias, two native fish species identified as vulnerable in the 2009 ‘Action plan for South Australian freshwater fishes’, has been found in the vicinity of this site within the last five years (Nick Whiterod, 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.
Stormwater runoff from some urban areas causing occasional high water velocities, containing nutrients and sediments (causing habitat disturbance, algal growth and aquatic weeds).
Natural Resources SA Murray–Darling Basin is working closely with local government through various projects including: Strengthening Basin Communities, funded under the Water for the Future Program to develop Integrated Water Management Plans; the implementation of Water Sensitive Urban Design principles in development planning and conditions; encouraging the implementation of Best Practice Stormwater Management Guidelines. The NRM Board also administers the statutory requirements of the NRM Act relating to Water Affecting Activities.
Observed Condition
Expected Condition
