Finniss River, near Finniss
2010 Aquatic Ecosystem Condition Report
- Permanently wet, slow-flowing, freshwater river in autumn and spring.
- Moderately diverse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of moderate nutrient enrichment.
- Riparian vegetation was mostly introduced grasses and gums.
About the location
Finniss River is a large stream in the southern Mount Lofty Ranges that rises east of Yundi and flows in an easterly direction where it eventually discharges into the Lower Murray, northeast of Goolwa. It receives flow from Meadows, Blackfellows and Bull creeks in the upper reaches and Tookayerta Creek in the lower reach, several kilometres south of Finniss.
The major land uses are cattle and sheep grazing with minor areas of vineyards, forestry, rural residential living and native vegetation. The monitoring site was located on Winery Road, about two kilometres south of Finniss.
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 nutrient enrichment, poor riparian habitat and fine sediment deposition.
A moderately diverse community of about 31 species of macroinvertebrates was collected from the flowing creek, 5–12 metres wide and up to 85 cm deep, in autumn and spring 2010. Fast-flowing riffle habitat was present in autumn but was too small to sample and small areas of flowing water were present in both seasons due to the channelling of water through the culverts under the road.
The community was dominated by large numbers of generalists and species tolerant to poor water quality such as amphipods (Austrochiltonia australis), chironomids and baetid mayflies (Cloeon). It also included smaller numbers of flatworms, snails (including the introduced Potamopyrgus and Physa), leeches, worms, freshwater shrimp, beetles, mosquitoes, biting midges, blackfly larvae, waterbugs, odonates and caddisflies. No sensitive or rare species were found but several species normally associated with flowing habitats were recorded, including a dytiscid beetle (Platynectes decempunctatus), whirligig beetle (Macrogyrus), chironomid (Rheotanytarsus) and unidentified blackfly larvae.
The only fish collected was the introduced mosquitofish (Gambusia) but some native Common Galaxias (Galaxias maculatus) were also seen during the autumn survey.
The water was fresh to moderately fresh (salinity of 1,250 mg/L in autumn and 910 mg/L in spring), well oxygenated (72–77% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (0.28–0.72 mg/L) and phosphorus (0.02–0.04 mg/L).
The sediments were dominated by detritus with algae, clay, gravel and sand also present; sampled taken from below the surface were sulphidic, probably due to the decay of organic matter in the sediments. A deposit of 1–5 cm of silt covered the riverbed in autumn.
A moderate amount of phytoplankton was recorded in spring, when filamentous algae (Cladophora) covered over 10% of the site. Large growths of aquatic plants were recorded in autumn when over 35% of the channel was covered by a range of floating (Azolla and Spirodela), submerged (Stuckenia) and emergent species (Phragmites, Typha, Cyperus, Hydrocotyle, Isolepis, Triglochin and Schoenoplectus). The riparian zone consisted of introduced grasses, reeds and weeds under a canopy of River Red Gums. The surrounding vegetation was cropping and grazing land with a few scattered gum trees.
Special environmental features
Finniss River provides habitat for at least one native fish and several flow-dependent macroinvertebrates in the lower reaches. Recent fish surveys in the catchment have also recorded the presence of at least four threatened fish species (Mountain Galaxias, Southern Pygmy Perch, Murray Hardyhead and Congolli) from the mid to lower sections of the creek (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.|