A total of 38 sites were sampled from the Western Mount Lofty Ranges in autumn and spring 2016. These sites were located throughout the region, ranging from the Light River in the north to Back Valley Creek in the south. Rainfall patterns in the region are dominated by winter rains and annual averages range from about 1,000 mm at Mount Lofty to less than 400 mm at Mallala in the Mid North. The generally low hills and flat plains of the Mount Lofty Ranges have been extensively cleared since European settlement, and only about 15% of the original vegetation remains (Environment Protection Authority 2008). Land-use is dominated by agriculture (mostly stock grazing and cereal cropping) and residential living, with patches of remnant native vegetation largely confined to conservation parks, steep hills, gullies, along creek-lines, and as part of roadside vegetation.
Sites monitored in the Adelaide and Mount Lofty Ranges during 2016 were considered to be in a Very Good to Very Poor condition. No sites were considered to be in an Excellent condition. Of the sites assessed, two sites (5%) were in Very Good condition with little change to animal and plant life; 18 sites (47%) were considered to be Good condition with only minor changes to animal and plant life; 8 sites (21%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; 9 sites (24%) were in Poor condition with evidence of major changes in animal and plant life; and 1 site (3%) was in a Very Poor condition with evidence of severe changes in animal and plant life and major loss of ecosystem function.
The sites rated Very Good and Good were located in the higher rainfall catchments (>600 mm annual rainfall) from the Fleurieu Peninsula (eg First Creek, Tunkalilla Creek, Callawonga Creek, Boat Harbour Creek, The Deep Creek, Balaparudda Creek and Myponga River) and Southern Mount Lofty Ranges (eg First Creek, Sixth Creek, Brownhill Creek, Scott Creek, Jacobs Creek and Little Para River).These sites were characterized by their moderately diverse to diverse macroinvertebrate communities, presence of several rare, sensitive and/or flow-dependent species, they mostly had well vegetated riparian zones, and most had low to occasionally moderate nutrient concentrations when sampled in 2016.
The sites rated in Fair condition showed evidence of nutrient enrichment (eg high nutrient concentrations, large growths of algae and/or aquatic plants, high chlorophyll concentrations) but were distinguished by the presence of only a few rare or sensitive species. The Fair sites tended to occur in streams with reasonable riparian habitats and some remnant native vegetation in their catchments but receive significant runoff from agricultural or peri-urban land uses. These included parts of several major (e.g. North Para and Sturt rivers) and numerous smaller streams from the Adelaide Hills (e.g. Cox, Aldgate, Brownhill and Tanunda Creeks), and two streams from the Fleurieu Peninsula (First Creek and Campbell Creek downstream from Talisker mine).
The Poor sites were from largely cleared catchments with riparian habitats consisting mainly of introduced plants with a few isolated gum trees. They included Back Valley Creek from the Fleurieu Peninsula and sites from the Light, South Para and Torrens rivers and Millers, Inverbrackie and Pedler creeks from the Southern Mount Lofty Ranges. These sites had few aquatic macroinvertebrates present and lacked rare or sensitive species, and often showed evidence of damage caused by high salinity levels and nutrient enrichment.
The Very Poor site was from Walker’s Creek within the North Para River catchment near Freeling. It was characterized by the lack of a functioning riparian zone, poor water quality including high salinity and gross nutrient enrichment, and limited range of only a few pollution tolerant macroinvertebrates.
The aquatic macroinvertebrate communities of most streams were dominated by tolerant species and included lower numbers of rare and sensitive species. Chironomids (including Paramerina, Procladius, Cricotopus, Thienemanniella, Tanytarsus and Chironomus), amphipods (Austrochiltonia) and snails (Potamopyrgus, Angrobia and Physiella) were particularly common from the streams sampled. Where flowing water (eg riffles) was present, large numbers of blackfly larvae (Austrosimulium furiosum and Simulium ornatipes), a chironomid (Rheotanytarsus), mayflies (Atalophlebia and Thraulophlebia), stoneflies (Illiesoperla and Dinotoperla) and caddisflies (Cheumatopsyche and Taschorema) were often recorded. The slow to non-flowing pools usually provided habitat for water mites, waterbugs (Micronecta, Microvelia and Anisops), beetles (Sternopriscus, Platynectes and Scirtidae), yabbies (Cherax destructor), shrimp (Paratya), introduced snails (Physiella and Potamopyrgus), mosquitoes (Aedes and Anopheles), flies from the Family Dixidae, mayflies (Cloeon and Tasmanocoenis), caddisflies (Hellyethira, Lectrides and Triplectides), stoneflies (Dinotoperla and Riekoperla), damselflies from the family Coenagrionidae and dragonflies from the family Telephlebiidae.
Nearly all sites sampled showed some evidence of nutrient enrichment, either by the high concentrations of nitrogen and phosphorus in the water or by the presence of large growths of filamentous algae, phytoplankton, and/or aquatic plants. Many creeks and rivers had significantly disturbed riparian zones with cropping or other introduced grasses and weeds often being the dominant vegetation on the banks. The few streams with more extensive riparian zones were generally located in conservation parks or hilly country where most of the overstorey was dominated by native trees and shrubs. Agricultural runoff carrying nutrients, salt and fine sediment, with the latter exacerbated by bank erosion caused by stock damage, were also significant stressors affecting the condition of many of the degraded streams in the region.
The median water quality data from sites sampled during 2016 indicated that streams from the Western Mount Lofty Ranges were generally fresh (salinity of about 436 mg/L), well oxygenated (8.2 mg/L), alkaline (pH>7) and with moderate to high concentrations of nutrients such as nitrogen (0.78 mg/L) and phosphorus (0.04 mg/L).
Flowing streams in the region 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 range of rare and sensitive species that frequent freshwater, flowing riffle habitats were collected from the better sites, including stoneflies (Newmanoperla thoreyi, Illiesoperla mayii and Riekoperla naso), mayflies (Tasmanophlebia, Centroptilum, Offadens, Nousia fuscula, Atalophlebia and Thraulophlebia), dragonflies (Hemigomphus and Austrogomphus), caddisflies (Ulmerochorema, Taschorema, Anisocentropus, Atriplectides, Oxyethira, Lingora, Leptorussa, Orthotrichia, Triplectides similis and members of the Family Tasimiidae), beetles (Simsonia and Sclerocyphon), blackflies (Paracnephia, Austrosimulium and Simulium melatum), and a chironomid (Riethia).
A few species were not collected during this sampling period but have been recorded from the region in recent years (2011, 2013 or 2015), including thaumaleid flies (Austrothaumalea), chironomids (Harrissius, Stempellina and Harnischia) and a caddisfly (Apsilochorema). Given the lack of recent land use changes or significant disturbances (eg fire or drought) over this time period, they probably still occur in parts of the less disturbed streams in the region that were not sampled in 2016.
Two threatened species of fish were also recorded from the better streams during 2016, including the Mountain Galaxias (Galaxias olidus) and Climbing Galaxias (Galaxias brevipennis). Several other significant fish have also been recorded from a number of coastal streams in the region during recent fish surveys, including Southern Pygmy Perch, Congolli, Freshwater Catfish and various eels and lampreys (Hammer et al. 2009).
