Riparian vegetation dominated by gums, bracken, weeds and introduced grasses.
Area map
About the location
Wild Dog Creek rises near Myponga and flows west into Carrickalinga Creek which discharges into Yankalilla Bay. The major land uses in the 837 hectare catchment are grazing pastures (44%), sown grass (18.5%), native vegetation (16%) and conservation park (15%). The monitoring site was located just downstream of the Myponga Conservation Park, about 6.5 kilometres south from Myponga.
In summary
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.
Findings
A diverse community of at least 64 species of macroinvertebrates was collected from this flowing creek, 2.7 m wide and up to 28 cm deep in spring 2011 and autumn 2012. The community consisted of a range of sensitive, and generalist and pollution tolerant species, including worms, amphipods, beetles, crane flies, mosquitoes, biting-midges, flow-dependent blackfly larvae, 18 different types of non-biting midges, mayflies, true bugs, stoneflies and caddisflies. Many rare and sensitive taxa were found including non-biting midges (Stempellina and Stenochironomus), mayflies (Offadens, Atalophlebia and Thraulophlebia), a stonefly (Austrocerca) and caddisflies (Taschorema and Triplectides similis). Whirligig beetles and yabbies were also seen at the site and the frog Crinia was heard calling.
The water was fresh (salinity ranged from 604-707 mg/L), well oxygenated (88-93% saturation) and clear, with moderate concentrations of nutrients such as nitrogen (0.44-0.45 mg/L) and phosphorus (0.02-0.03 mg/L).
The sediments were dominated by cobbles, pebbles, gravel and detritus in the flowing sections and sand with some silt, clay and detritus in the pools. Samples taken from below the surface were sandy grey and showed no signs of being anaerobic or lacking oxygen. Deposits of silt covered the streambed to a depth of 5 cm in places and more than 10% of the bank was eroded due to higher stream flows, reduced riparian vegetation stabilising the banks and stock trampling in places.
A moderate amount of phytoplankton (chlorophyll a ranged from 2.45-6.36 µg/L) was recorded but no filamentous algae was seen. More than 10% of the site was covered in spring 2011 by aquatic plants, although fewer were noted in autumn 2012 due to lower flows in the creek. Aquatic plants present at this site included Juncus, Cyperus, Isolepis, Polygonum and weedy Rorrippa. The riparian zone comprised bracken, eucalypts, and introduced grasses and blackberries while the surrounding vegetation was grazing land with grass, and some tall eucalypts and bracken.
Special environmental values
Wild Dog Creek provides important habitat for a number of rare, sensitive and flow-dependent aquatic macroinvertebrates from the region.