Paris Creek, south of Macclesfield
2010 Aquatic Ecosystem Condition Report
- Permanently wet, moderately fresh, flowing creek in autumn and spring.
- Sparse macroinvertebrate community with one sensitive species.
- Obvious signs of gross nutrient enrichment.
- Riparian vegetation mostly consisted of introduced grasses and weeds under native shrubs.
- Moderately eroded banks due to flood and cattle damage.
About the location
Paris Creek is a small stream in the southern Mount Lofty Ranges. It rises east of Meadows and flows in an easterly direction, where it eventually discharges into Middle Creek, and then the Angas River. The major land use is cattle grazing, with some areas of native vegetation further upstream.
The monitoring site was located on Paris Creek Road, about four kilometres south of Macclesfield.
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, bank erosion, fine sediment deposition and a degraded riparian zone.
A sparse community of about 24 species of macroinvertebrates was collected from the slow-flowing creek, 2–5 metres wide and up to 40 centimetres deep, in autumn and spring 2010. A section of fast-flowing riffle habitat was present in spring but was too small to sample. The community was dominated by species tolerant to poor water quality such as amphipods (Austrochiltonia australis), corixid waterbugs (Micronecta) and chironomids (including Chironomus, Dicrotendipes and Cricotopus). It also included smaller numbers of snails (including the introduced Physa), mites, yabbies, beetles, soldierflies, mosquitoes, mayflies, notonectid and veliid waterbugs, and caddisflies. The only sensitive species collected was a single mayfly nymph from the Family Leptophlebiidae in spring.
The water was fresh to moderately fresh (salinity of 2,309 mg/L in autumn and 655 mg/L in spring), well oxygenated (83–110% saturation), clear in autumn but turbid and slightly coloured in spring, with moderate to high concentrations of nutrients such as nitrogen (0.64–1.11 mg/L) and phosphorus (0.06–0.12 mg/L).
The sediments were dominated by silt, clay, detritus and algae; samples taken from below the surface were black and anaerobic in autumn, indicating too much organic matter had entered the creek in the past. Heavy siltation was evident at the site with more than 10 centimetres of silt covering the creekbed in spring. Over 10 metres of bank showed signs of erosion due to cattle and flood damage.
A large amount of phytoplankton was recorded during both autumn and spring, and a type of filamentous alga (Spirogyra) covered more than 65% of the site in autumn. Over 65% of the channel was covered by aquatic plants in spring, largely due to the prolific growth of cumbungi (Typha). Other plants recorded included both submerged (Myriophyllum and Stuckenia) and emergent species (introduced Rorippa, Isolepis and Triglochin).
The narrow riparian zone consisted of native species such as acacias and tea-trees (Leptospermum) over an understorey of introduced weedy shrubs (e.g. broom), weeds and grasses. The surrounding vegetation was grazing land with a few scattered gum trees.
Special environmental features
Paris Creek provides habitat for one sensitive mayfly family. The catchment may also support the threatened Mountain Galaxias in refuge pools further upstream, since it was collected from the creek in 2004 (M. Hammer, Aquasave Consultants, 2009).
Pressures and management responses
|Livestock have direct access at the site and upstream, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).||The SA Murray–Darling Basin NRM Board acknowledges the significant impacts that livestock have on aquatic environments and seeks to provide free technical advice and incentives to land managers for fencing and other works as funding permits. Funding incentives are limited in value and extent and require land managers to volunteer to be involved.|
|Limited riparian vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The SA Murray–Darling Basin NRM Board recognises that the management of riparian vegetation requires a long-term, integrated approach to achieve ecosystem benefits. The board therefore provides free technical advice on a range of topics for land managers and various incentives for works as funding permits.|
|Insufficient natural water flows resulting from water extraction and climate variability (reducing ecological integrity.||The SA Murray–Darling Basin NRM Board is working with the Department for Water and the community to develop a water allocation plan and licensing system which aim to balance social, economic and environmental needs for water. The objective for providing water to the environment is to maintain and/or restore self-sustaining water-dependent ecosystems which are resilient in times of drought.|
|Widespread introduced trees and weeds in the riparian zone at the site and upstream in the catchment (reducing habitat quality).||The SA Murray–Darling Basin NRM Board recognises the limitations of available funds relative to the scale of the degradation caused by introduced trees and weeds. The NRM Board provides free technical advice and community education to assist land managers in dealing with the integrated management of aquatic weeds. The NRM Board also has a targeted process, as directed by state government, to strictly prioritise its investment in weed control activities as funds are limited. The NRM Board actively seeks funding opportunities for weed control; most opportunities are for locations where biodiversity outcomes can be achieved.|