Fifty-four sites were sampled from the region during autumn and spring 2012. Of these, 29 were located in the Flinders Ranges from Hookina Creek near Hawker in the south to Arkaroola Creek in the north. The rest were located in the Lake Eyre Basin with 10 sites from the west near Oodnadatta and 15 sites from the Cooper Creek and Diamantina River catchments in the east. Land use was dominated by agriculture (sheep and cattle grazing in the Flinders Ranges and cattle grazing in the Lake Eyre Basin) and nature conservation, with smaller areas away from streams used for mining, rural living and tourism.
Sites monitored in the South Australian Arid Lands NRM region during 2012 were considered to be in a Very Good to Poor condition. No sites were assigned to the Excellent condition class and given the scale of stock grazing and feral animal grazing it is unlikely that any stream in the region remains unaffected by past human activities. Of the sites assessed, five sites (9%) were in a Very Good condition with little change to animal and plant life from expected natural condition; 29 sites (54%) were considered to be Good condition with only minor changes to animal and plant life; 18 sites (33%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; and two sites (4%) were in Poor condition with evidence of major changes in animal and plant life, and moderate changes to the way the ecosystems functioned.
The better sites from the Flinders Ranges included Oraparinna Creek, Tributaries of Oratunga Creek at First Spring and Snob’s Hut Spring and Balcanoona Creek at Grindell’s Hut Spring, and a similar high rating was given to Yardaparinna Creek, north from Oodnadatta in the Western Lake Eyre Basin. The sites from the Flinders Ranges were located in the middle of the ranges from Oraparinna, within the Flinders Ranges National Park in the south, to Arkaroola in the Vulkathunha-Gammon Ranges, to the north. They were characterised by the presence of naturally occurring native vegetation throughout their catchments, a wide diversity of sediment types present within each stream channel and limited evidence of any significant damage caused by animals accessing each site. Of these, the Snob’s Hut Spring was the only Flinders site that held water in 2012, where the shallow flowing riffles and still pool habitats supported a wide range of common, regionally significant and flow-dependent species at the site sampled during the year. The site from Yardaparinna Creek was also wet in 2012, and was surrounded by natural habitat features, supported many types of aquatic plants and animals which included several regionally significant species, and was consequently rated highly despite showing some minor damage caused by cattle accessing the site.
In contrast, the worst sites were from two Western Lake Eyre Basin streams that had only a few aquatic species present and appeared to be significantly affected by nutrients (Neales Creek at Algebuckina Waterhole) and/or high salinity (Peake Creek).
The sites assigned to either the Good or Fair ratings showed the effects from slight to moderate nutrient enrichment during at least one of the sampling periods (e.g. high nutrient concentrations, large growths of algae and/or aquatic plants, anaerobic sediments, dominance by plant or detrital feeding and generalist macroinvertebrates) and were largely distinguished by the number of rare and sensitive species and the extent of damage to the riparian zone caused by stock or feral animals. The Good sites occurred in streams with more extensive riparian habitats and minor enrichment indicators, and included many of the freshwater streams in the Flinders Ranges and a range of sites on both sides of the Lake Eyre Basin. The Fair sites generally had less effective buffering vegetation and showed evidence of more damage caused by grazing animals. They included both saline and freshwater streams from the Flinders Ranges, and many of the downstream sites on the Diamantina River and Cooper Creek systems on the Eastern Lake Eyre Basin and two medium-sized tributary streams of the Macumba River on the Western Lake Eyre Basin.
It is important to note that a major assumption of the conceptual models developed for the Flinders Ranges and Lake Eyre Basin was that the high levels of nutrients (nitrogen and phosphorus) recorded from most streams in the Far North region was actually sourced from human activities within each upstream catchment, rather than from some unknown natural source. This is consistent with the poor nutrient status attributed to most Australian soils (e.g. National Land & Water Resources Audit 2001) and would help to explain the widespread distribution of streams throughout the Flinders and Far North with high nutrient concentrations and other indicators of nutrient enrichment. Consequently, it was assumed that historical and current stock grazing land uses, feral animal grazing, and in the case of Cooper Creek and Diamantina River, cropping and grazing practices further upstream in Queensland, all contributed towards the enrichment effects seen in many streams across the region.
The aquatic macroinvertebrate communities of most streams in the region were typically dominated by a small number of very tolerant and/or generalist species, with the better sites generally providing suitable habitats for at least some rare and sensitive species. Flinders Ranges streams were generally dominated by baetid mayflies (Cloeon), waterbugs (Microvelia, Anisops, Agraptocorixa and Micronecta) and chironomids (Procladius, Cricotopus, Tanytarsus and Chironomus), with smaller numbers of yabbies, mosquitoes (Anopheles), beetles (Platynectes, Necterosoma, Sternopriscus, Allodessus and Eretes), biting midges (Bezzia), caenid mayflies (Tasmanocoenis tillyardi), odonates (Coenagrionids, Hemianax and Hemicordulia) and caddisflies (Triplectides australis and Hellyethira simplex) also commonly recorded from most sites. A number of rare and uncommon species were also recorded during 2012, including snails (Isidorella and Glyptophysa), an amphipod (Melitidae), waterbug (Hydrometra) and some beetles (Hyphydrus and Limbodessus), chironomids (Kiefferulus and Harnischia) and caddisflies (Lectrides varians and Hydroptila scamandra).
Streams from the Western Lake Eyre Basin were generally dominated by waterbugs (Micronecta and Anisops), beetles (Necterosoma, Hyphydrus, Allodessus and Antiporus) and chironomids (Procladius, Ablabesmyia, Dicrotendipes, Tanytarsus and Cladotanytarsus), with lower numbers of prawns (Macrobrachium), snails (Glyptophysa), baetid mayflies (Cloeon), dragonflies (Hemicordulia and Orthetrum) and caddisflies (Triplectides australis). The uncommon and rarely collected species included several chironomids (Paraborniella, Coelopynia and Larsia), a caenid mayfly (Tasmanocoenis), mite (Limnesia) and a few caddisflies (Ecnomus, Oecetis and Lectrides).
A similar assemblage of waterbugs, chironomids, prawns, baetid mayflies and a caddisfly (Triplectides australis) also usually dominated streams from the Eastern Lake Eyre Basin but there was often a different assortment of beetles (Enochrus, Sternopriscus and Platynectes) and low numbers of mosquitoes, mites and molluscs (Velesunio, Corbiculina and Glyptophysa) recorded at most sites sampled. The rarely collected species included the chironomids (Coelopynia, Harnischia and Larsia), caenid mayfly (Wundacaenis dostini) and two snails (Centrapala and Thiara).
Streams that flowed provided more habitat complexity and supported a wider range of aquatic species than those that ceased to flow or dried up for at least part of the year. A number of commonly occurring flow-dependent species were recorded from riffles in the Flinders Ranges but none were recorded from the Lake Eyre Basin streams sampled in 2012 despite their occurrence in previous years (see Madden et al. 2002). Blackfly larvae (Simulium ornatipes), a dytiscid beetle (Platynectes decempunctatus adults and larvae), chironomid (Rheotanytarsus) and caddisfly (Cheumatopsyche) were found among riffles from the more regularly flowing streams throughout the Flinders Ranges.
Most streams in the region had limited riparian habitats, which is probably at least partly due to the arid climate that occurs throughout much of the Flinders Ranges and Lake Eyre Basin. The vegetation along the majority of creeks and rivers comprises a single line of gum trees (mostly River Red Gums with Coolibah Trees dominating among parts of the Eastern Lake Eyre Basin) over a sparse understorey of introduced grasses and weeds. The exception was where streams passed through conservation parks and the understorey plants were mostly native species with a few weeds. The more permanent streams generally supported submerged and emergent plants within their channels but most ephemeral streams either lacked aquatic plants or only had a few scattered sedges lining creek channels.
Finally, the results from sampling in 2012 may have been influenced by recent climatic conditions because the region was generally drier than normal, with only the Arkaroola to Leigh Creek area receiving above average annual rainfall due to a thunderstorm dropping over 180 mm of rain in a few days in February 2012. In contrast, the other parts of the Flinders Ranges received only 69% of the annual average rainfall at Hawker in the south up to 85% at Marree in the north, and Oodnadatta in the Lake Eyre Basin was similarly drought affected and only received 52% of its annual rainfall (Bureau of Meteorology summary statistics from http://www.bom.gov.au). This was reflected in rainfall patterns and hydrographs from gauge stations located in the Flinders Ranges but did not appear to significantly affect flow patterns in the Diamantina River or Cooper Creek (see surface water archive at http://www.waterconnect.sa.gov.au), which are driven by cyclonic and summer monsoonal rains in Queensland (Armstrong 1990). Consequently, the results highlight the particularly significant stream sites in the Flinders Ranges that persist during a dry period and other sites that are adversely affected by a range of land use and possibly climatic disturbances
