Minno Creek, near Long Gully
2012 Aquatic Ecosystem Condition Report
Ephemeral, slow-flowing, freshwater creek in spring 2011 but was dry in autumn 2012
Diverse macroinvertebrate community with three sensitive species
Riparian vegetation comprised of mostly weeds with native vegetation beyond
About the location
Minno Creek is a small stream that rises within the Belair National Park and flows in a westerly direction in the park and then turns in a southerly direction before discharging to the Sturt River in Coromandel Valley. The major land uses in the 387 hectare catchment are the national park (49%) and rural and urban residential areas (30%). The monitoring site was located within Belair National Park in the upper reaches of the catchment near Long Gully, about 3 kilometres upstream from the park entrance.
The creek was given a Fair rating because the site sampled showed evidence of moderate changes in ecosystem structure, and some changes to the way the ecosystem functions. There was evidence of human disturbance including signs of nutrient enrichment, fine sediment deposition and weeds dominating the understorey vegetation on the banks. However, the stream still provided habitat for some sensitive macroinvertebrate species.
A moderately diverse community of at least 37 species of macroinvertebrates was collected from this slow-flowing creek, 1.5 m wide and 13 cm deep in spring 2011; the site was dry in autumn 2012. The community was dominated by species tolerant to pollution such as worms, the snail Glyptophysa and round worms. The community also included smaller numbers of springtails, beetles (including five different types of diving beetles), craneflies, nine types of non-biting midges and two species of caddisfly. Some sensitive species were also found including two flow-dependent species of blackfly larvae (Austrosimulium and Simulium) and the stonefly Austrocerca.
The sediments were dominated by silt and clay, with some detritus also present. Samples taken from below the surface were grey clays and silt which were anaerobic, or lacking oxygen. Some deposits of silt covered the streambed to a depth of about 5 cm in places and a small area of bank erosion was evident due to a lack of riparian vegetation stabilising the banks.
A small amount of phytoplankton (chlorophyll a 4.76 µg/L) but no filamentous algae was seen. More than 10% of the site was covered with aquatic plants including Polygonum, Cyperus and Rumex. The riparian zone consisted of bracken, and weeds such as blackberries, blue periwinkle, willows, water couch, wild mint and introduced grasses. The surrounding vegetation at the site was native scrubland with gums, bracken and native cherry trees on one bank and introduced grass on the other bank.
Special environmental values
Minno Creek provides habitat for two flow-dependent species of blackfly larvae and one stonefly.
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