Forty-six sites were sampled from the region during autumn and spring 2013. They were located from the Gawler River catchment in the north to Hindmarsh River on 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 region during 2013 were considered to be in a Very Good to Very Poor condition. No sites were assigned to the Excellent condition class and given the scale of vegetation clearance and nutrient enrichment evident in 2013 (and sampled in past years) it is unlikely that any stream in the region remains unaffected by human activities. Of the sites assessed, two sites (4%) were in Very Good condition with little change to animal and plant life; 10 sites (22%) were considered to be Good condition with only minor changes to animal and plant life; 14 sites (30%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned; 18 sites (39%) were in Poor condition with evidence of major changes in animal and plant life, and moderate changes to the way the ecosystems functioned; and 2 sites (4%) were Very Poor with evidence of major changes in animal and plant life, and the way the ecosystems functioned.
The better sites were located in high rainfall catchments (>600 mm annual rainfall) from the Fleurieu Peninsula (eg First Creek, The Deep Creek, Callawonga Creek and Boat Harbour Creek) and Southern Mount Lofty Ranges (eg First Creek, Sixth Creek, Brownhill Creek, Scott Creek, Jacobs Creek, and a site on the Little Para River upstream from the reservoir. 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 2013.
In contrast, the worst sites were from largely cleared catchments with degraded riparian habitats that lacked any significant patches of native vegetation. They included an ephemeral tributary of Yankalilla River that was dry in both seasons sampled, and Walker’s Creek that had few aquatic macroinvertebrates present and showed evidence of damage caused by high salinity, nutrient enrichment and smothering by fine sediment.
The sites assigned to either the Fair or Poor ratings showed evidence of significant nutrient enrichment (eg high nutrient concentrations, large growths of algae and/or aquatic plants, anaerobic sediments) but were distinguished by the number of rare and sensitive species and extent of damage to the riparian zone. The Fair sites tended to occur in streams with more extensive riparian habitats and some remnant native vegetation in their catchments and included many of the larger streams in the Adelaide Hills (eg Sturt, Onkaparinga and North Para rivers). The Poor sites included streams receiving significant runoff from agricultural and urban land uses, including parts of several major (e.g. Torrens, North Para and South Para rivers) and numerous smaller (eg Aldgate, Cox, Inverbrackie, Millers and Greenock creeks) streams from the Adelaide Hills, and a few coastal streams from the Fleurieu Peninsula (eg Bungala River and its’ tributaries, and Back Valley Creek).
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. The amphipod crustacean (Austrochiltonia) was usually the most abundantly collected macroinvertebrate along with chironomids (including Paramerina, Procladius, Cricotopus, Paralimnophyes, Tanytarsus, Chironomus, Dicrotendipes and Polypedilum). Where flowing water was present, large numbers of blackfly larvae (Austrosimulium furiosum and Simulium ornatipes), chironomids (Rheotanytarsus), mayflies (Atalophlebia and Thraulophlebia) and caddisflies (Cheumatopsyche) were often recorded. The slow to non-flowing pools usually provided habitat for waterbugs (Micronecta, Microvelia and Anisops), beetles (Sternopriscus, Necterosoma, Platynectes and Scirtidae), yabbies (Cherax destructor), shrimp (Paratya), introduced snails (Physa and Potamopyrgus), mosquitoes (Aedes, Anopheles and Culex), biting midges (Bezzia and Culicoides), mayflies (Cloeon and Tasmanocoenis), caddisflies (Lectrides and Triplectides australis), stoneflies (Dinotoperla evansi) and flies from the Family Dixidae. Low numbers of a range of worms, mites, dragonflies and damselflies were also found at most sites.
Streams that flow 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 and Newmanoperla thoreyi), mayflies (Offadens, Centroptilum and Tasmanophlebia), dragonflies (Hemigomphus gouldii and Austrogomphus guerini), caddisflies (Taschorema, Ulmerochorema, Oxyethira, Orphninotrichia, Lingora and Atriplectides), beetles (Simsonia), blackflies (Paracnephia and Simulium melatum), thaumaleid flies (Austrothaumalea) and a chironomid (Riethia). These streams also occasionally provided habitat for State-listed threatened fish, including Mountain Galaxias (Galaxias olidus) and Climbing Galaxias (Galaxias brevipennis).
Most streams in the region were distinguished by the presence of a single line of River Red Gums or weedy willows or ash trees on the banks, over introduced grasses and weeds. 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 but in most cases the understorey had still been invaded by weeds and introduced grasses.
The median water quality data from sites sampled during 2013 indicated that streams from the Western Mt Lofty Ranges were generally fresh (salinity of about 725 mg/L), well oxygenated (>100% saturation and 9 mg/L), alkaline (pH>7) and enriched with nutrients such as nitrogen (>0.9 mg/L) and phosphorus (0.05 mg/L).
Many rare and sensitive macroinvertebrates were found in 2013, including mites (Family Oxidae), stoneflies (Riekoperla naso and Austrocerca tasmanicum), and the above-listed flow-dependent species that were collected from the better streams in the Adelaide Hills and Fleurieu Peninsula.
A number of species were not collected during this sampling period but had been recorded from the region in 2011, including several chironomids (Harrissius, Apsectrotanypus, Stempellina and Harnischia) and caddisflies (Anisocentropus, Triplectides similis and members of the Family Tasimiidae), a mayfly (Nousia fuscula) and a beetle called a waterpenny (Sclerocyphon). Given the lack of any 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.
Two threatened species of fish were recorded from the better streams in the region during 2013, including the Mountain Galaxias and Climbing Galaxias. 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).
