A total of 32 sites were sampled from the region during autumn and spring 2017. Of these, 19 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 (LEB) with seven sites from the west near Oodnadatta and six 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 2017 were considered to be in a Good to Poor condition. No sites were assigned the Excellent or Very Good condition ratings and given the scale of feral goat and stock grazing it is unlikely that any stream in the region remains unaffected by past human activities. Of the sites assessed, 20 sites (63%) were considered to be Good condition with only minor changes to animal and plant life; nine sites (28%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; and three sites (9%) 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 dry and wet streams. The dry sites included Wilpena and Balcanoona creeks and the wet sites included Reedy, Puttapa, Artimore, Eregunda, Bunyeroo, Brachina, Parachilna, Paralana creeks and Third Spring in Oratunga Creek catchment. These sites were distributed from 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.
All sites sampled in the Lake Eyre Basin (LEB) held water when sampling was carried out in autumn 2017. Nine of the 13 sites sampled were in Good condition, including sites from Macumba, Neales (2 sites) and Yardaparinna creeks on the Western LEB and Warburton (2 sites), Diamantina ( 2 sites) and Cooper (2 sites) from the Eastern LEB.
The Good sites were characterised by the dominance of naturally occurring vegetation throughout their catchments, a wide diversity of sediment types within each stream channel, and limited evidence of any significant damage caused by feral and stock animals accessing each site.
The Fair sites included Pekina Creek in the southern Flinders Ranges and Nilpena, Aroona, Italowie, Arkaroola, Mount Chambers and Wirrealpa creeks in the mid to northern Flinders Ranges. These sites included lowland and gorge streams and generally had less effective riparian buffering vegetation and showed more significant nutrient enrichment than the better streams, largely caused by feral goat and stock animal grazing damage.
In the Lake Eyre Basin, Lindsay Creek and Algebuckina Waterhole at Neales Creek were also assigned Fair ratings due to the extent of nutrient enrichment responses noted at each site.
The Poor sites included Baratta and Hookina creeks near Hawker in the mid Flinders Ranges and Peake Creek near Oodnadatta in the western Lake Eyre Basin. These sites were adversely affected by gross nutrient enrichment and high salinity also contributed towards the limited range of aquatic life inhabiting Peake Creek.
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 was sourced from human activities within each catchment, rather than from a natural source. This is consistent with the poor nutrient status attributed to most Australian soils (e.g. National Land & Water Resources Audit 2001). 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 high nutrient concentrations and enrichment effects seen in many streams across the region.
The aquatic macroinvertebrate communities of streams in the region were typically dominated by a range of tolerant and/or generalist species, with the better sites generally providing suitable habitats (often flowing riffles) for at least some rare and sensitive species. Flinders Ranges streams were generally dominated by waterbugs (Microvelia, Enithares and Anisops), dytiscid beetles (Platynectes, Necterosoma, Hyphydrus and Eretes), chironomids (Procladius,Paramerina, Tanytarsus and Chironomus) and baetid mayflies (Cloeon), with smaller numbers of flatworms, mites (Arrenurus), yabbies, hydrophilid beetles (Enochrus, Berosus and Limnoxenus), mosquitoes (Anopheles), biting midges (Bezzia), caenid mayflies (Tasmanocoenis tillyardi), odonates (Coenagrionidae, Hemianax and Hemicordulia) and caddisflies (Triplectides australis and Hellyethira simplex) also commonly recorded. A number of rare and uncommon macroinvertebrates were also recorded during 2017, including molluscs (Ferrissia and Isidorella), a regionally endemic amphipod (Brachina invasa, Family Melitidae), baetid mayfly (Offadens congruens), leptophlebiid mayfly (Thraulophlebia inconspicua), waterbug (Hydrometra) and caddisflies (Cheumatopsyche, Hydroptila and Ecnomus).
Streams from the Western Lake Eyre Basin were generally dominated by waterbugs (Micronecta), beetles (Necterosoma, Sternopriscus and Cybister), biting midges (Nilobezzia, Culicoides and Bezzia) and chironomids (Coelopynia, Procladius, Dicrotendipes, Tanytarsus and Cladotanytarsus), with smaller numbers of prawns (Macrobrachium), yabbies (Cherax), snails (Glyptophysa), baetid mayflies (Cloeon), and caddisflies (Triplectides australis). The uncommon and rarely collected macroinvertebrates included a mite (Unionicola), chironomids (Coelopynia, Larsia, Nanocladius and Harnischia), caenid mayfly (Tasmanocoenis nr arcuata), and caddisflies (Ecnomus and Oecetis). Mussel shells (Velesunio) occur on the banks of the fresher creeks.
A similar assemblage of macroinvertebrates were recorded from the streams draining into the Eastern Lake Eyre Basin. The most notable difference was the richer mollusc fauna, comprising mussels (Velesunio and Corbicula) and regionally rare snails (Centrapala and Thiara), and the presence of several other rare species including biting midges (Alluauodomyia and Dasyhelea) and an odonate (Austrogomphus).
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 2017 despite their occurrence in previous years (see Madden et al. 2002). Blackfly larvae (Simulium ornatipes), a dytiscid beetle (Platynectes decempunctatus adults and larvae), baetid mayfly (Offadens) and caddisfly (Cheumatopsyche) were found among riffles from the more regularly flowing streams in 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 2017 may have been influenced, in part, by recent climatic conditions because the region was generally drier than normal throughout the eastern Lake Eyre Basin-Flinders Ranges but was wetter than average in the western Lake Eyre Basin (see the Bureau of Meterology). The average annual rainfall in Moomba was 174 mm but while 2016 was a wet year with 270 mm rainfall, after a wet January the rest of 2017 was very dry with only 98 mm of rain recorded. Similar patterns were recorded from Arkaroola and Leigh Creek with lower than average rain recorded in 2017, and particularly dry conditions in February-March, May, September and December. On the western part of the Lake Eyre Basin at Oodnadatta, however, the annual rainfall of 176 mm was exceeded in both 2016 (288 mm) and again in 2017 (218 mm). This probably contributed towards only three streams from the Flinders Ranges maintaining sufficient riffle habitat to sample in spring, compared to autumn when an additional two streams had riffle habitats. None of the Lake Eyre Basin sites had flowing habitats but the hydrology of streams such as the Cooper and Diamantina are generally driven by cyclonic and summer monsoonal rains in Queensland rather than local rainfall (e.g. Armstrong 1990).
