Neales Creek, Algebuckina Waterhole
2012 Aquatic Ecosystem Condition Report
- Permanent, non-flowing waterhole when sampled in autumn 2012
- Sparse macroinvertebrate community with no rare or sensitive species
- Water was moderately fresh, turbid and enriched with nutrients
- Riparian vegetation consisted of native trees and shrubs and some aquatic plants were present
About the location
Neales Creek is a medium sized stream in the Far North of the State that rises about 15 km south-east from Welbourn Hill as two main branches that flow in an easterly direction, before merging into the one channel north from Oodnadatta and eventually discharging into the western margins of Lake Eyre North during very wet years. The major land use in the catchment is cattle grazing. The monitoring site was located in the mid reaches of the stream on a small track off the Oodnadatta Track, just north from Algebuckina and about 55 km south-east from Oodnadatta.
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 from nutrient enrichment of the waterhole, which when combined with the small number of aquatic macroinvertebrates recorded, resulted in a Poor condition rating being assigned to the site.
A sparse community of only 5 species of macroinvertebrates was collected from the non-flowing waterhole, 50 m wide and over 1 m deep, in autumn 2012. The community was not dominated by any species but included low numbers of caddisflies (Triplectides australis), freshwater prawns (Macrobrachium), waterbugs (Micronecta and Anisops), chironomids (Dicrotendipes) and dytiscid beetles (Sternopriscus). The prawn was the only typical riverine species collected whereas the other species were all saline tolerant insect groups, capable of flying to other wetted habitats in the region if conditions deteriorate in the waterhole. No regionally rare or significant species were collected or any long-lived species that would normally be expected to occur at a permanently wet waterhole in the Lake Eyre Basin. The absence of mites, yabbies, snails and mussels was unexpected, given the habitats present at the site when it was sampled in May 2012; resident fish were unlikely to consume all these groups and the salinity did not approach critical freshwater tolerance values of around 3-5,000 mg/L, so the reason for the poor macroinvertebrate diversity was not obvious from the data collected. A single Desert Goby was the only fish collected and no other fish were seen at the waterhole.
The water was moderately fresh (salinity of 1,985 mg/L), well oxygenated (107% saturation), turbid, and with high concentrations of nutrients such as nitrogen (1.28 mg/L) and phosphorus (0.13 mg/L).
The sediments were dominated by clay and silt, with smaller amounts of detritus and sand also present; samples taken from below the surface were black clays and silts, which indicate that the sediments occasionally become anaerobic, or lacking in oxygen. No evidence of any significant bank erosion or signs of cattle accessing and defaecating on the banks were recorded during the autumn 2012 site inspection.
A large growth of phytoplankton was present (chlorophyll a 39 Âµg/L) which included a small amount of blue-green algae or cyanobacteria (chlorophyll b 5.5 Âµg/L). No filamentous algal growths were seen at the site but over 10% of the waterhole was covered by aquatic plants. The riparian vegetation was dominated by lignum, acacias and gum trees on the moderately well vegetated banks (50-79% vegetative cover). The surrounding vegetation comprised scattered native woodland over grasses.
Special environmental features
Algebuckina Waterhole on Neales Creek was sampled for fish using a range of nets in November 2011 and again in May 2012, as part of the Lake Eyre Basin Rivers Assessment (Cockayne et al. 2013). The waterhole provides an important habitat for at least 6 native species (Bony Bream, Desert Rainbowfish, Lake Eyre Hardyhead, Barred Grunter, Desert Goby and Lake Eyre Golden Perch) but also supports low numbers of an introduced pest species (Mosquitofish). Consequently, while the site was assigned a poor condition rating based on the aquatic macroinvertebrate and water quality results, the waterhole is a significant refuge habitat for native fish in the catchment and probably region.
Pressures and management responses
|Livestock in the catchment are exerting excessive grazing pressure on vegetation, 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.|
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- Cockayne, B., Schmarr, D., Duguid, A. & R. Mathwin (2013). “Lake Eyre Basin Rivers Assessment (LEBRA) 2012 Monitoring Report.” Report to LEBRA Oversight Group.