Edillilie Creek, near Edillilie
2010 Aquatic Ecosystem Condition Report
- Permanently wet, shallow stream consisting of a flowing channel in autumn and isolated pools in spring.
- Sparse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of nutrient enrichment and salinity effects.
- Riparian vegetation limited and mostly consisting of samphire and introduced grasses.
- Some bank erosion and fine sediment deposits in the channel.
About the location
Edillilie Creek is a small stream in Eyre Peninsula that rises west of Koppio and flows in a westerly direction before discharging into Glengyle Creek. The major land uses are grazing and cropping, with areas of native vegetation adjacent to the site near the railway line and further upstream in the catchment. The monitoring site was located off the Tod Highway, about three kilometres north of Edillilie.
The creek was given a Very Poor rating because the site sampled showed evidence that the ecosystem was in a severely degraded condition with major changes to both the animal and plant life, and a significant breakdown in the way the ecosystem functions. There was considerable evidence of human disturbance, including high salinity, fine sediment deposition, poor riparian habitats and nutrient enrichment.
A sparse community of about 10 species of macroinvertebrates was collected from the stream, up to five metres wide and 15 cm deep, in autumn and spring 2010. In autumn, the stream consisted of a connected slow-flowing channel that included small sections of fast-flowing riffle habitat, whereas in spring the water had subsided and only isolated pool habitats were present. The community was dominated by species tolerant to high salinity and poor water quality such as culicine mosquitoes and chironomids (including Procladius and Tanytarsus). It also included amphipods, isopods, springtails, beetles and soldierflies. The latter was the only macroinvertebrate collected from the riffle habitat in autumn. No sensitive or rare species were found.
The water was saline (salinity of 7,000 mg/L in autumn and 10,646 mg/L in spring), well oxygenated (87–90% saturation), frothy, turbid and coloured, with moderate to high concentrations of nutrients such as nitrogen (1.25–2.34 mg/L) and phosphorus (0.03–0.1 mg/L).
The sediments were dominated by clay, detritus, silt, sand and cobbles; samples taken from below the surface were well aerated in autumn but slightly sulphidic and anaerobic in spring. A deposit of 1–5 cm of silt covered the creekbed in spring and some minor bank erosion (<10% of the site), caused by a track that crosses the creek, was recorded in autumn.
Moderate growths of phytoplankton were recorded in both seasons sampled, and over 10% of the site was covered in filamentous algae (Cladophora) in spring. No aquatic plants were seen growing in the channel or on the water’s edge. The narrow riparian zone consisted of samphire and introduced grasses with a few scattered paperbark and gum trees. The surrounding vegetation consisted of cereal cropping land, and patches of mallee scrub and chenopod shrubland.
Special environmental features
Pressures and management responses
|Livestock have direct access at the site and upstream in the catchment, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).||
The Eyre Peninsula NRM Board promotes managing land to improve water quality. This includes incentives for:
|Limited natural riparian vegetation at the site and upstream in the catchment, providing minimal buffer protection from catchment landuses (reducing habitat quality).|
|Saline groundwater inflow (reducing ecological integrity).||The Eyre Peninsula NRM Board promotes the revegetation of recharge areas known to contribute to dryland salinity and encourages the adoption of perennial pastures as an alternative to annual cropping in these areas.|