Baratta Creek, Baratta Springs
2012 Aquatic Ecosystem Condition Report
- Permanent stream with isolated pools in autumn and spring 2012
- Moderately diverse macroinvertebrate community with one regionally sensitive species
- Water was moderately fresh, clear and high in nutrients
- Riparian vegetation consisted of native shrubs and trees over poorly vegetated banks damaged by feral animal and stock access
About the location
Baratta Creek comprises a small network of streams that rise around Wilyerpa Hill in the Southern Flinders Ranges, drain southwards where they merge, and then the creek flows eastwards where it discharges into the Siccus River and further downstream into the Lake Frome Basin; flow only extends into the Siccus River and Lake Frome during exceptionally wet years. The only land use in the 5,607 hectare catchment, upstream from the site sampled, is grazing natural vegetation. The monitoring site was located at Baratta Springs, about 60 km east from Hawker.
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, fine sediment deposition and some bank erosion but the stream still provided habitat for a few sensitive and uncommonly collected aquatic macroinvertebrates and two aquatic plants.
A moderately diverse community of at least 26 species of macroinvertebrates was collected from the creek, 5.1-6.1 m wide and over 1.7 m deep, in autumn and spring 2012. The creek consisted of a series of isolated pools in both seasons sampled. The community was dominated by moderate to large numbers of chironomids (Procladius, Cladotanytarsus, Tanytarsus, Polypedilum and Cladopelma), baetid mayflies (Cloeon) and waterbugs (Micronecta and Anisops). It also included smaller numbers of mites (Koenikea), yabbies (Cherax destructor), beetles (Allodessus, Sternopriscus, Macrogyrus and Scirtidae), biting midges (Nilobezzia), various fly families (Tabanidae and Stratiomyidae), waterbugs (Microvelia, Ranatra, Agraptocorixa and Enithares), dragonflies (Hemianax and Hemicordulia) and caddisflies (Ecnomus continentalis and Triplectides). Most species collected were mobile, tolerant and generalist insect groups but notable exceptions included the presence of an uncommonly collected type of mite and ecnomid caddisfly, yabbies that burrow into the sediments, and large numbers of regionally sensitive but commonly occurring mayflies. However, no regionally rare or specialist species were recorded.
The water was moderately fresh (salinity ranged from 2,062-2,867 mg/L), well oxygenated (133-143% saturation), clear but slightly coloured, and with moderate to high concentrations of nutrients such as phosphorus (0.02-0.04 mg/L) and nitrogen (0.63-1.24 mg/L).
The sediments were dominated by bedrock and detritus, with cobble, pebble, silt and sand also present; samples taken from below the surface were anaerobic and sulphidic silts and sands, indicating that the sediments were lacking in oxygen and a harsh environment for most burrowing species to be able to survive in. Over 1 cm of silt was deposited in the channel and about 10 m of bank showed evidence of erosion caused by stock accessing the stream and its’ banks; goat, sheep and kangaroo faeces were deposited throughout the site during 2012.
Moderate to large amounts of phytoplankton were recorded (chlorophyll a ranged from 2.8 Âµg/L in autumn to 14.4 Âµg/L in spring) but no filamentous algal growths were seen at the site inspected. Over 10% of the channel was covered by emergent aquatic plants, including sedges (Cyperus) and a few patches of cumbungi (Typha). The riparian vegetation was dominated by acacias, White Cypress Pines and a few gums over sedges and grasses on the poorly vegetated banks (<25% vegetative cover). The surrounding vegetation at the site comprised low native woodland dominated by acacias and gums over native grasses.
Special environmental features
Baratta Creek is a largely natural, permanent stream in the eastern margins of the Southern Flinders Ranges that provides habitat for a wide range of aquatic macroinvertebrate species, including baetid mayflies and many generalist types of aquatic insects. No significant environmental features were, however, noted from the springs based on the aquatic life recorded in 2012.
Pressures and management responses
|Feral goats around Baratta Springs are exerting excessive grazing pressure on vegetation, causing erosion and adding excessive nutrients to the watercourse.||The SA Arid Lands Natural Resources Management Board provides technical advice and incentives for the management of introduced weeds and feral pest animals, as funding permits. Pest management efforts are guided by a region-wide strategy, based on risk assessment, to determine priority locations and species. Funding is actively sought from a number of sources to support region-wide integrated management.|
|Livestock have direct access at the site and upstream 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.|