Tributary of Peter Creek, near Kangarilla Hill
2012 Aquatic Ecosystem Condition Report
Permanently wet freshwater creek which was flowing in spring 2011 and autumn 2012
Diverse macroinvertebrate community with many rare and sensitive species
Emerging signs of nutrient enrichment
Riparian vegetation mostly native species but with some invasion by weeds
About the location
Tributary of Peter Creek is a small stream that rises north of Kangarilla and flows south and then west to join Peter Creek, before discharging into the Onkaparinga River. The major land uses in the 972 hectare catchment are grazing pastures (46%), softwood production (28%) and native vegetation (12%). The monitoring site was located upstream of Dashwood Gully Road, about 3 kilometres, south-east from Kangarilla.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was evidence of human disturbance including emerging signs of nutrient enrichment and weedy riparian zones but the stream provides habitat for several rare and sensitive species of macroinvertebrates.
A diverse community of at least 81 species of macroinvertebrates was collected from this flowing creek, 3 m wide and up to 36 cm deep in spring 2011 and autumn 2012. Worms, hydrobiid snails, including the introduced Potamopyrgus, and non-biting midges dominated the fast flowing habitat, while worms, mites, mayflies and non-biting midges dominated the slow-flowing pools. Freshwater shrimp, springtails, beetles, biting midges, blackfly larvae, dance fly larvae, non-biting midges, mayflies, waterbugs, stoneflies and several species of caddisfly were also collected from the site but in smaller numbers. Many sensitive and rare species were found including the non-biting midge Bryophaenocladius, mayflies (Offadens, Atalophlebia and Thraulophlebia), stoneflies (Dinotoperla and Austrocerca), and caddisflies (Taschorema, Hydroptila calcara, Hydroptila scamandra, Lingora, and Triplectides similis). Water skinks and yabbies were also seen at the site.
The water was fresh (salinity ranged from 570-1,010 mg/L), well oxygenated (93-99% saturation) and clear, with high concentrations of nutrients such as nitrogen (0.63-1.3 mg/L) and phosphorus (0.03-0.05 mg/L).
The sediments were dominated by cobbles, pebbles, detritus and clay. Samples taken from below the surface were brown clays and sands and showed no evidence of being anaerobic or lacking oxygen. Only small deposits of silt covered the streambed to a depth of 1 cm in places and no bank erosion was noticed at the site sampled.
A small amount of phytoplankton (chlorophyll a ranged from 1.94-2.01 µg/L) was recorded but no filamentous algae was seen. More than 10% of the site was covered by aquatic plants including the submerged Chara and emergent Cyperus and Isolepis. The riparian zone consisted of gums, native shrubs, introduced grasses and blackberries. The surrounding vegetation was native scrubland with gums, Melaleuca, wattles and bracken present.
Special environmental values
Tributary of Peters Creek provides important habitat for a diverse assemblage of aquatic invertebrates including many rare, sensitive and flow-dependent species from the region.
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