Glengyle Creek, near Wangary
2015 Aquatic Ecosystem Condition Report
Permanently wet, saline, slow-flowing creek in autumn and spring
Sparse macroinvertebrate community with no rare or sensitive species
Obvious signs of gross nutrient enrichment
Riparian vegetation was dominated by introduced grasses, samphire and paperbark trees
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 south-westerly direction before eventually discharging into Lake Wangary. The major land uses are sheep and cattle grazing and cropping, with minor areas of native vegetation and swamp further upstream. The monitoring site was located off Yorkies Gully Road, about eight kilometres north-east from 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 15 species of macroinvertebrates (9 in autumn and 11 in spring) was collected from the slow-flowing creek, 3.7-4 metres wide and up to 19 centimetres deep, in autumn and spring 2015. The community was dominated by species tolerant of high salinity and poor water quality, such as the Salt Lake Snail (Coxiella), chironomids (Tanytarsus and Procladius) and brinefly larvae (Ephydridae). It also included smaller numbers of worms, amphipods (Austrochiltonia), dytiscid (Necterosoma) and hydrophilid beetles (Limnoxenus and Berosus), mosquitoes (Aedes) and damselflies (Austrolestes). The site lacked any rare, sensitive or species normally associated with freshwater (eg mayflies, stoneflies, caddisflies, odonates, waterbugs, richer assemblage of molluscs, crustaceans and dipterans). The only fish seen were some juvenile hardyheads in spring.
The water was saline (salinity of 14,371 mg/L in autumn and 25,184 mg/L in spring), well oxygenated (91-120% saturation), clear and slightly turbid, and with high concentrations of nutrients such as nitrogen (2.83-3.92 mg/L) and phosphorus (0.07-0.17 mg/L).
The sediments were dominated by silt, detritus and clay, with smaller amounts of cobble, pebble, sand and filamentous algae (only spring) also present. Samples taken from below the surface were grey clays and silts that released sulfide when tested in spring, indicating that the sediments were occasionally anaerobic and a harsh environment for most benthic species to be able to tolerate. A moderately thick deposit of 1-5 centimetres of silt covered the creekbed in places. No significant signs of any bank erosion were recorded despite the presence of cattle and kangaroo droppings on the banks indicating that stock access the stream on occasion.
A moderate amount of phytoplankton (chlorophyll a ranged from 3.4-8.1 µg/L) was recorded but filamentous algal growths (Spirogyra) were only recorded in spring. Up to 35% of the channel was covered by submerged charophytes and Sea Tassel (Ruppia) and emergent plants (Cotula). The riparian zone extended over 40m wide on one bank and consisted of paperbark trees over introduced grasses, weeds and samphire. The surrounding vegetation was cereal cropping and grazing land with a few scattered rums remaining in the local landscape.
Special environmental features
None detected in 2015.
Pressures and management responses
Livestock have direct access at the site and upstream in the catchment, causing sediment erosion and adding excessive nutrients.
The Eyre Peninsula NRM Board administer the Water Affecting Activities permits and polices for the region. This process allows the Board to grant or refuse permits to undertake certain activities affecting water resources. The process is the region’s primary means of preventing any potential impact on the environmental integrity of surface water catchments.
The Eyre Peninsula NRM Board continues to promote managing land to improve water quality. This includes incentives for:
The Eyre Peninsula NRM Board also undertakes a native freshwater fish monitoring program throughout this catchment.
Limited natural riparian vegetation at the site and upstream in the catchment, providing minimal buffer protection from catchment land uses.