Bunyeroo Creek, Bunyeroo Gorge
2012 Aquatic Ecosystem Condition Report
- Dry in autumn and spring 2012
- Unlikely to be enriched with nutrients when wet because most of the catchment lies in a national park
- Some bank erosion caused by past flood damage and evidence of sheep accessing the creekbed was noted in spring
- Riparian vegetation consisted of a native gums and shrubs
About the location
Bunyeroo Creek is a moderately sized, intermittent stream that rises north from St Mary Peak in the Flinders Ranges National Park, and flows west through Bunyeroo Gorge and onto the Lake Torrens plains, where it eventually discharges into the Yudna Lagoons, about 5 km east from Lake Torrens. The major land use in the 11,338 hectare catchment, upstream from the site, is national park with minor areas used for grazing natural vegetation and roads. The monitoring site was located off the Wilco Fire Track in the ABC Range, about 17 km north from Wilpena.
The creek was given a Good rating because the site sampled showed evidence of relatively minor changes in ecosystem structure and function. There was evidence of human disturbance from sheep accessing the creekbed but the dry creek provided a wide range of sediment types and near natural vegetation assemblages on the banks and surrounding landscape.
The sediments were dominated by gravel, cobble, pebble, boulder and detritus, with smaller amounts of bedrock, sand and silt also present. Samples taken from below the surface were grey sands and gravels, and showed no signs that the sediments were recently anaerobic, or lacking in oxygen. About 10 m of bank showed evidence of erosion caused by past flood damage. Sheep faeces were noted throughout the creekbed of the site inspected in spring but only kangaroo and emu droppings were noted in autumn.
No aquatic plants were recorded from the site but the presence of dried, bleached algae on rocks in the creekbed indicates that small pools may become enriched with nutrients when it rains. A number of young River Red Gums were growing in the channel which highlights how dry the stream has been in recent times. The riparian vegetation was dominated by River Red Gums and acacias over hopbush and other native shrubs on the moderately well vegetated banks (50-79%% vegetative cover). The surrounding vegetation at the site comprised native woodland dominated by White Cypress Pine.
Special environmental features
Bunyeroo Creek is an ephemeral stream that lies in the Flinders Ranges National Park. Few roads occur in the catchment and the major disturbances from human activities relates to occasional vehicle access for tourists and feral animal damage. No significant environmental values were recorded from the dry site in 2012, however, previous sampling of the same site in 1997 recorded a rich assemblage of aquatic species from the pools and flowing riffles that were present during a wetter period. They included many sensitive and flow dependent species (e.g. snails Isidorella and Austropeplea, blackflies Simulium, baetid mayflies Offadens, caddisflies Cheumatopsyche) as well as a range of mites, beetles, dragonflies, flies, waterbugs and caddisflies.
Pressures and management responses
|Livestock and feral animals have direct access at the site and upstream in the catchment, exerting excessive grazing pressure, causing sediment erosion and adding excessive nutrients to the watercourse.||The SA Arid Lands Natural Resources Management Board recognizes that both direct and diffuse impacts on aquatic ecosystem condition can occur through direct stock access and excessive grazing pressure from stock and feral herbivores. Technical advice and incentives are offered to land managers in the region, as funding permits, to address these impacts through appropriate activities suitable for the context. In addition, projects are underway across the region to identify, prioritise and address impacts at key aquatic sites.|