Toolillie Creek, near Tod River Reservoir
2010 Aquatic Ecosystem Condition Report
- Permanent saline stream with small areas of flowing habitat only present in spring.
- Sparse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of gross nutrient enrichment.
- Riparian vegetation dominated by weeds and grasses.
About the location
Toolillie Creek is a small stream in Eyre Peninsula that rises to the east of Bald Hill and flows in an easterly direction before discharging into the western side of the Tod Reservoir. The major land uses are sheep grazing and cropping, and minor areas of native vegetation.
The monitoring site was located on Toolillie Gully Road (also called Warner Road), about seven kilometres south-west of Koppio.
Eyre Peninsula NRM Regional Summary 2010
The creek was given a Poor rating because the site sampled showed evidence of major changes in ecosystem structure and moderate changes to the way the ecosystem functions. There was considerable evidence of human disturbance, including nutrient enrichment, fine sediment deposition, livestock accessing the banks and limited vegetative cover in the riparian zone.
A sparse community of about 18 species of macroinvertebrates was collected from this creek, 2–3 metres wide and up to 50 centimetres deep, in autumn and spring 2010. Flowing riffles were only present in spring but were too small to sample. The community was dominated by species tolerant to poor water quality and high salinity such as mites, amphipods, springtails, chironomids and damselflies, and also included low numbers of beetles and mosquitoes. No sensitive or rare species were found.
The water was saline (salinity of 14,000 mg/L in autumn and 4,550 mg/L in spring), well oxygenated (84–137% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (0.84–1.29 mg/L) and phosphorus (0.03–0.05 mg/L).
The sediments were dominated by detritus, silt and algae. Samples taken from below the surface were black, sulfidic and anaerobic, indicating that too much organic material was present in the creek. Heavy siltation was evident during both seasons sampled with more than 10 centimetres of silt covering the creekbed. Over half of the site also showed signs of bank erosion due to stock trampling and accessing the creek.
More than 35% of the site was covered by filamentous algae (Cladophora) in both autumn and spring, and a large amount of phytoplankton was present in autumn. Aquatic plants covered more than 35% of the channel and included submerged (Stuckenia and an unidentified charophyte) and emergent species (Schoenoplectus, Juncus and Cotula).
The riparian zone consisted of introduced grasses and weeds and included a few scattered gums trees and melaleucas. The surrounding vegetation at the site was mostly crops and grazed grassland, with some smaller areas of natural scrubland.
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.|
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