Seventeen sites were sampled from the region during autumn and spring 2015. They were located from the Gawler River catchment in the north to the Fleurieu Peninsula in the south. Land-use was dominated by agriculture (stock grazing and cereal cropping) and residential living, with patches of remnant native vegetation largely confined to conservation parks, steep hills, gullies, along creeklines and as part of roadside vegetation.
Sites monitored in the Adelaide and Mount Lofty Ranges during 2015 were considered to be in a Very Good to Poor condition. No sites were considered to be in either Excellent or Very Poor condition. Of the sites assessed, two sites (12%) were in Very Good condition with little change to animal and plant life; 3 sites (18%) were considered to be Good condition with only minor changes to animal and plant life; 8 sites (47%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; and 4 sites (23%) were in Poor condition with evidence of major changes in animal and plant life.
The sites rated Very Good and Good were located in high rainfall catchments (>600 mm annual rainfall) from the Fleurieu Peninsula (eg First Creek and Callawonga Creek) and Southern Mount Lofty Ranges (eg First Creek and Sixth Creek).These sites were characterised by their moderately diverse to diverse macroinvertebrate communities, presence of several rare, sensitive and/or flow-dependent species, they had well vegetated riparian zones, and most had low to occasionally moderate nutrient concentrations when sampled in 2015. The sites rated in Fair condition showed evidence of nutrient enrichment (eg high nutrient concentrations, large growths of algae and/or aquatic plants, anaerobic sediments) but were distinguished by the presence of only a few rare or sensitive species, and evidence of damage to the riparian zone. 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. Torrens, North Para and South Para rivers) and numerous smaller (e.g. Aldgate, Cox, Brownhill and Cudlee Creeks) streams from the Adelaide Hills, and a coastal stream on the Fleurieu Peninsula (Congeratinga Creek).
The Poor sites were from largely cleared catchments with riparian habitats consisting mainly of introduced plants and patches of native vegetation. They included Back Valley Creek and Pedler Creek on the Fleurieu Peninsula, the Torrens River, near Mt Pleasant and Gould Creek near the Little Para Reservoir. These sites had few aquatic macroinvertebrates present and lacked rare or sensitive species, and showed evidence of damage caused by high salinity levels and nutrient enrichment.
The aquatic macroinvertebrate communities of most streams were typically dominated by a small number of very tolerant species and included low numbers of rare and sensitive species. Chironomids (including Paramerina, Procladius, Cricotopus, Paralimnophyes, Tanytarsus, Chironomus, Dicrotendipes and Polypedilum) were the most abundantly collected macroinvertebrate along with amphipods. Where flowing water was present, large numbers of blackfly larvae (Austrosimulium furiosum and Simulium ornatipes), a chironomid (Rheotanytarsus), mayflies (Atalophlebia and Thraulophlebia), a stonefly (Illiesoperla) and a caddisfly (Cheumatopsyche) 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.
Many sites throughout the region showed evidence of nutrient enrichment either by the high recorded concentrations of nitrogen and phosphorus or by the presence of large growths of filamentous algae, phytoplankton, and/or aquatic plants. Some creeks and rivers had significantly disturbed riparian zones with cropping or other introduced grasses and weeds often being the dominant vegetation on the streambanks. 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, and both sediment and bank erosion from stock damage, were also significant stressors affecting the condition of many streams in the region.
The median water quality data from sites sampled during 2015 indicated that streams from the Western Mt Lofty Ranges were generally fresh (salinity of about 434 mg/L), well oxygenated (8 mg/L), alkaline (pH>7) and with moderate concentrations of nutrients such as nitrogen (0.53 mg/L) and phosphorus (0.03 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 (Illiesoperla mayii, Riekoperla naso and Newmanoperla thoreyi), mayflies (Offadens, Centroptilum and Nousia fuscula), dragonflies (Hemigomphus gouldii and Austrogomphus), caddisflies (Taschorema, Apsilochorema, Oxyethira, Lingora, Triplectides similis and members of the Family Tasimiidae), beetles (Simsonia and Sclerocyphon), blackflies (Paracnephia, Austrosimulium and Simulium melatum), and chironomids (Riethia, Aphroteniella and Apsectrotanypus).
A number of species were not collected during this sampling period but had been recorded from the region in recent years (2011 or 2013), including thaumaleid flies (Austrothaumalea), several chironomids (Harrissius, Stempellina and Harnischia) and caddisflies (Orphninotrichia, Atriplectides, Anisocentropus, a mayfly (Tasmanophlebia). Given the lack of recent land use changes or significant disturbances caused by fire or drought over this time period, these species probably still occur in small reaches of the less disturbed streams in the region that were not sampled in 2015.
Two threatened species of fish were recorded from the better streams during 2015, 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).