Tookayerta Creek, near Tooperang
2008 Aquatic Ecosystem Condition Report
- An important creek that supports a large number of sensitive and rare fish and insect species
- Early warning signs that nutrient and sediment loads are affecting the ecosystem, and its animal and plant life
- Active intervention required to prevent further deterioration and maintain fresh, permanent water flows
About the location
Tookayerta Creek rises south of Mount Compass in the southern Mount Lofty Ranges, and flows east where it ultimately discharges into the Finniss River. The major land uses are dairy farming and cropping, with minor areas of rural residential living and native vegetation also present.
The monitoring site was located downstream of a track off Cleland Gully Road in the mid reaches of the creek, about one kilometre west of Tooperang.
The creek was given a Good rating at this site because the ecosystem showed relatively minor changes to its animal and plant life. However there were clear, emerging signs that nutrient levels were starting to affect the stream, and the native vegetation along its banks was limited, which may lead to further decline in the future.
At the time of sampling in November 2008, the creek was only one to two metres wide, with both flowing riffles and still-water edges. A diverse community of 54 macroinvertebrate species was found in the riffle habitats, and 44 species were collected from still areas at the edge of the creek. Both habitats were dominated by large numbers of worms, chironomids and tiny crustaceans called water scuds (Austrochiltonia australis). Most species were tolerant to pollution but several rare species that are sensitive to high nutrient levels and poor water quality were also found in low numbers.
The water was fresh (salinity of 190 mg/L), well oxygenated and clear although slightly coloured from naturally occurring tannins. However, there were high concentrations of nutrients such as nitrogen (0.69 mg/L) and phosphorus (0.12 mg/L).
Sediments in the creekbed were mostly made up of sand, silt and fine detritus. Samples taken from below the surface layer were smelly and anaerobic, or lacking in oxygen, indicating that too much organic matter had entered the creek in the past.
Large areas of aquatic plants such as introduced Watercress (Rorippa nasturtium-aquaticum) and Cumbungi (Typha domingensis) were found in the riffle areas. Smaller patches of introduced rushes (Juncus articulatus) also occurred in the channel, while introduced pasture grasses dominated the riparian zone.
More than 50% of the creekbanks were extensively eroded, presumably caused by high water flows after heavy rain and exacerbated by a lack of buffering trees, shrubs and other plants on the banks.
Special environmental features
Tookayerta Creek is one of the few streams in South Australia that flows for most of the year along much of its length. It provides habitat for sensitive species that are rare in the region and State, including stoneflies (Austrocerca tasmanica and Leptoperla tasmanica), mayflies (Atalophlebia australasica, Koorrnonga inconspicua, Offadens and Tasmanophlebia) and caddisflies (Orthotrichia bishopi, Taschorema and Ulmerochorema membrum). The upper to middle reaches of the creek also support populations of threatened fish species such as Mountain Galaxias, Southern Pygmy Perch and River Blackfish (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.|
|Drought (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.|