Glengyle Creek, near Wangary
2010 Aquatic Ecosystem Condition Report
- Permanently wet, slow-flowing saline creek in autumn and spring.
- Sparse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of gross nutrient enrichment.
- Riparian vegetation was limited and only consisted of introduced grasses and terrestrial species.
About the location
Glengyle Creek is a moderately sized stream in Eyre Peninsula that rises as Edillilie creek north of Edillilie and drains in a southwesterly direction before eventually discharging into Lake Wangary. The major land uses are sheep grazing and cropping, with minor areas of native vegetation and swampland further upstream. The monitoring site was located off Yorkies Gully Road, about eight kilometres north-east of Wangary.
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 and poor riparian habitat.
A sparse community of about 16 species of macroinvertebrates was collected from the slow-flowing creek, up to 26 metres wide and more than one metre deep, in autumn and spring 2010. The community was dominated by species tolerant to high salinity and poor water quality such as a snail (Coxiella), springtails and dytiscid beetles (including Necterosoma). It also included smaller numbers of isopods, several other beetles, craneflies, mosquitoes, biting midges, soldierflies, chironomids (Procladius, Tanytarsus barbitarsis and Dicrotendipes) and damselflies. No sensitive or rare species were found.
The water was saline (salinity of 14,575 mg/L in autumn and 15,316 mg/L in spring), well oxygenated (65–100% saturation), slightly turbid and coloured, with moderate to high concentrations of nutrients such as nitrogen (1.52–2.33 mg/L) and phosphorus (0.04–0.06 mg/L).
The sediments were dominated by algae and detritus, with smaller amounts of gravel, silt and clay also present; samples taken from below the surface were aerated and not obviously anaerobic despite the large amount of organic matter in the sediments. A moderately thick deposit of 1–5 cm of silt covered the creekbed in places.
More than 65% of the channel was covered by filamentous algae (Cladophora and Spirogyra) and a submerged plant called Sea Tassel (Ruppia) covered over 10% of the site in spring. The very narrow riparian zone consisted of native shrubs such as paperbarks and dead gum trees over samphire and introduced grasses. The surrounding vegetation was cereal cropping and grazing land.
Special environmental features
Glengyle Creek provides habitat for juvenile hardyhead, a commonly occurring salt tolerant fish from the region.
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.|