Campbell Creek, downstream from Talisker Mine
2016 Aquatic Ecosystem Condition Report
Permanent to nearly permanent flowing stream in autumn and spring 2016
Moderately diverse macroinvertebrate community with a few rare and sensitive species recorded
Water was saline, clear and enriched with nitrogen
- Riparian vegetation consisted of gums and wattles over a weedy understorey
About the location
Campbell Creek is a small stream located in the south-west corner of the Fleurieu Peninsula, adjacent to and west from The Deep Creek Conservation Park. It rises near Silverton at an elevation of about 300 m and flows in a southerly direction for several kilometres before eventually discharging into the Southern Ocean. The majority of its catchment lies within the 212 hectare Talisker Conservation Park and is dominated by native sclerophyll open forest and thick scrub. The park was purchased in 1976 to preserve the ruins of the Talisker silver and lead mine which operated near the headwaters of the creek from 1862-1872. The site sampled was located about 1.1 km from Rankang Road off a walking track, a few hundred metres downstream from the mine.
The creek was given a Fair rating because the site sampled showed evidence of changes in ecosystem structure and function. There was evidence of human disturbance due to the weedy riparian zone and elevated nitrogen concentrations recorded from the stream.
A moderately diverse community of at least 26 species of macroinvertebrates was collected from the creek (13 species in autumn and 22 in spring), 0.25-1.5 m wide and up to 27 cm deep, in autumn and spring 2016. The creek consisted of equal areas of shallow pools connected by moderately flowing riffles in autumn but in spring riffles were not as extensive and pools comprised about 70% of the stream habitat. The community was dominated by moderate numbers of scirtid beetle larvae and stonefly nymphs (Dinotoperla evansi and Austrocerca tasmanica), with moderate numbers of hypogastrurid springtails also collected from riffles in autumn and dytiscid beetle larvae were common in both habitats in spring. A number of other taxa were recorded in lower numbers including horsehair worms (Gordiidae), hydrobiid snails (Angrobia), hydrophilid beetles, dixids, mosquitoes, biting midges, chironomids, waterbugs, dragonflies and caddisflies. A few rare and sensitive species were collected, including a rare caddisfly (Leptorussa) and the stoneflies. The site lacked any large crustaceans such as amphipods and yabbies which are common in the region, although some small cyclopoid copepods were recorded from pools in spring. The community comprised mostly generalist and tolerant species capable of dispersing to more permanent water (insects) or surviving in damp sediments (snails and horsehair worms), suggesting the stream probably forms isolated pools or dries completely during most years.
The water was moderately fresh to saline (salinity ranged from 2,845-4,569 mg/L), with a neutral pH (6.99-7.38), generally well oxygenated (56-69% saturation), clear, and with mostly moderate to high concentrations of nutrients such as phosphorus (0.01-0.04 mg/L) and nitrogen (0.67-0.71 mg/L).
The sediments were dominated by bedrock, detritus, cobbles and pebbles, with filamentous algae also prominent in autumn. Samples taken from below the surface were mostly grey clays and silts that did not release any sulfide when tested, indicating that the sediments were well oxygenated. However, the black colour on the underside of rocks buried into the creek, suggest that the sediments have occasionally turned anaerobic and lacked oxygen. No evidence of any significant bank erosion was noted at the site and the only animal droppings seen near the creek were from kangaroos.
Only a moderate amount of phytoplankton was recorded during the autumn survey (chlorophyll a ranged from <0.1-4.2 μg/L), which was also when the largest growth of filamentous algae (Spirogyra) was observed (covering more than 35% of the channel whereas in spring the cover was <10%). Over 10% of the creek was also covered by aquatic plants, including sedges (Cyperus and Isolepis), rushes (Juncus) and cumbungi (Typha). The narrow riparian zone comprised gums and wattles over patches of sedges and bracken, along with weeds which included olives, bridal creeper, Arum lilies, wild roses and introduced grasses. The surrounding vegetation consisted of equal areas of cleared sheep grazing land and dense eucalypt woodland.
Special environmental features
The presence of a rare caddisfly and two stoneflies indicate this stream is capable of supporting a diverse range of aquatic life when it holds water for an extended period of time.
Pressures and management responses
Widespread introduced weeds in the riparian zone at the site and upstream
The Adelaide and Mount Lofty Ranges NRM Board has several pest plant (weed) mitigation and control programs. They work closely with landholders to control weeds on their property and to help stop the spread to other properties and waterways.
Nutrient inputs to the creek from numerous diffuse sources (potentially leading to excess growth of algae and aquatic weeds)
The Adelaide and Mount Lofty Ranges NRM Board land management program encourages and promotes managing land to improve water quality. This includes working with industry and landholders to ensure efficient use of fertilisers and discuss ways to reduce runoff of nutrients into waterways.
This aquatic ecosystem condition report is based on monitoring data collected by the EPA. It was prepared with and co-funded by the Adelaide and Mount Lofty Ranges NRM Board.