Uranno Creek, near Chinmina Hill
2010 Aquatic Ecosystem Condition Report
- Permanently wet, saline creek in autumn and spring.
- Sparse macroinvertebrate community that included one rare species of caddisfly.
- Obvious signs of moderate nutrient enrichment.
- Riparian vegetation consisted of introduced grasses and salt tolerant native species.
About the location
Uranno Creek is a small stream in Eyre Peninsula that rises near Uranno and drains in a north-easterly direction, where it discharges into Chinmina Creek. It forms part of the Salt Creek catchment that discharges into Tumby Bay. The major land uses are sheep grazing and native vegetation.
The monitoring site was located off Chinmina Hill Road, about eight kilometres south-west of Ungarra.
The creek was given a Fair rating because the site sampled showed moderate changes in ecosystem structure and some changes to the way the ecosystem functions. There was evidence of human disturbance, including nutrient enrichment and fine sediment deposition.
A sparse community of about 12 species of macroinvertebrates was collected from the creek, five metres wide and up to 70 centimetres deep, in autumn and spring 2010. The community was dominated by species tolerant to high salinity such as a salt-lake snail (Coxiella), chironomids (including Procladius and Tanytarsus) and a lestid damselfly (Austrolestes annulosus). It also included smaller numbers of amphipods (Austrochiltonia australis), beetles (including Necterosoma penicillatus and Berosus), mosquitoes, brineflies, notonectid waterbugs and a leptocerid caddisfly (Symphitoneuria wheeleri). The latter was the only rare species collected. The only fish seen in the creek was a salt tolerant native species called the Small-mouthed Hardyhead.
The water was saline (salinity of 15,061 mg/L in autumn and 11,136 mg/L in spring), well oxygenated (67–117% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (1.09–1.84 mg/L) and phosphorus (0.03–0.09 mg/L).
The sediments were dominated by detritus, silt, algae and cobbles; samples taken from below the surface were blackened, sulfidic and lacking in oxygen in spring. A deposit of 1–5 centimetres of silt covered the creekbed in both seasons.
Filamentous algae (Cladophora) and aquatic plants each covered over 10% of the channel. The submerged plant, Sea Tassel (Ruppia), was growing in the creek and an emergent macrophyte, a species of twig-rush (Baumea), was present on the banks.
The riparian zone consisted of introduced grasses and sedges, with a few paperbarks and samphire also present. The surrounding vegetation included paperbarks and gum trees over wattles, saltbush and introduced grasses.
Special environmental features
Uranno Creek provides habitat for a rarely collected, salt tolerant caddisfly (Symphitoneuria wheeleri) and a common species of native fish (Small-mouthed Hardyhead).
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.|