Locations
A total of 8 sites were sampled from the Eastern Mount Lofty Ranges in the Finniss, Bremer and Angas River catchments in spring 2020. Rainfall patterns in the region are dominated by winter rains and annual averages range from over 700 mm in the eastern hills and southern areas (eg Mount Barker, Kuitpo Forest, Mount Compass) to nearly 300 mm towards Callington and the plains near the River Murray (eg Black Hill). Land use is dominated by agriculture (grazing and dryland cropping) but also includes areas of irrigated vines and orchards, dairying, forests, urban areas, mines and remnant native vegetation.
The generally low hills and flat plains of the Mount Lofty Ranges have been extensively cleared post- European settlement, and only 15% of the original vegetation remains (EPA 2008). The Eastern Mount Lofty Ranges that drains towards the River Murray and Lower Lakes has been particularly favoured by cropping and grazing land uses, whereby only about 8% of the original pre-European vegetation (eg grassland and grassy woodland communities) remains (O’Connor et al 2008).
Key points
- Sites were sampled from the Finniss, Bremer and Angas River catchments, which all discharge into Lake Alexandrina in the Lower River Murray.
- 1 site was in Very Good condition, 5 sites were in Good condition and 2 in Fair condition but no sites re rated in an Excellent, Poor or Very Poor condition.
- The better sites were located in the Finniss River catchment on the Fleurieu Peninsula, and the two sites in fair condition occurred in the Angas and Bremer River catchments.
- Several rare and sensitive aquatic macroinvertebrates were recorded, particularly from within the Finniss River catchment.
- All streams showed evidence of nutrient enrichment.
- Riparian zones often lacked or had limited trees and shrubs lining stream edges that were covered by introduced weeds and grasses.
Findings
Sites monitored in the Eastern Mount Lofty Ranges during 2020 were considered to be in Very Good to Fair condition. No sites were assigned to the Excellent, Poor or Very Poor condition classes. Of the sites assessed, 1 (12%) was rated in Very Good condition with little change to animal and plant life, 5 (62%) were considered to be in Good condition with only minor changes to animal and plant life, and 2 (25%) were rated in Fair condition, with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned.
The site in Very Good condition was located in the upper reaches of Tookayerta Creek, south from Mount Compass on the Fleurieu Peninsula. It was characterised by the presence of several rare and sensitive species in the flowing freshwater habitats of this stream which also showed evidence of nitrogen enrichment when sampled.
The sites in Good condition were located within the Finniss River catchment on the Fleurieu Peninsula, including: 2 sites on the Finniss River north-east from Mount Compass, Blackfellows Creek near Kyeema Conservation Park, Ti Tree Creek near McHarg Creek, and Nangkita Creek off Willowburn Road east from Mount Compass. They all supported a high diversity of aquatic macroinvertebrates including at least a few rare and sensitive species but showed signs of slight to moderate nutrient enrichment and had degraded riparian vegetation lining each stream.
The sites assessed in Fair condition included Rodwell Creek in the Bremer River catchment and Middle Creek in the Angas River catchment. These streams had a lower diversity of aquatic macroinvertebrates, fewer rare or sensitive species, showed signs of significant nutrient enrichment and the riparian zones were limited in extent and highly degraded.
The aquatic macroinvertebrate communities of most streams were dominated by tolerant species such as an amphipod crustacean (Austrochiltonia), snails (introduced Potamopyrgus and Physa and native Austropygrus), mites (Familes Hygrobatidae, Hydryphantidae, Limnesiidae, Pionidae), waterbugs (Microvelia, Micronecta, Sigara, and Anisops) and chironomids (wide diversity but including Procladius, Paramerina, Cricotopus, Tanytarsus, Chironomus, Polypedilum and Dicrotendipes). A number of rare and sensitive species were found in the region in 2020 but most were recorded from the Finniss River catchment, particularly from Tookayerta and Nangkita creeks. These species are normally associated with permanent to near-permanently flowing, freshwater habitats and include the following: mayflies (Offadens confluens, Tasmanophlebia, Atalophlebia australasica, Atalophlebia australis, Nousia fuscula and Thraulophlebia inconspicua), stoneflies (Austrocerca tasmanicum, Illiesoperla mayii, Dinotoperla evansi and Leptoperla tasmanica), caddisflies (Taschorema evansi, Ulmerochorema membrum, Atriplectides dubius, Lingora aurata, Notalina spira, Triplectides similis), blackflies (Austrosimulium and Paracnephia), chironomids (Apsectrotanypus, Eukiefferiella and Riethia) and a dragonfly nymph (Austrogomphus guerini).
Median water chemistry of the sampled sites indicated the streams were fresh (conductivity 1,023 µS/cm which means the salinity was about 600 mg/L), alkaline (pH 7.8), and generally had moderate amounts of phosphorus (0.04 mg/L) and high concentrations of nitrogen (0.7 mg/L). Most sites showed evidence of nutrient enrichment, due to elevated nitrogen concentrations and the presence of moderate to large growths of filamentous algae, phytoplankton, and/or reeds and other types of aquatic plants.
Special environmental features
Several other rare and sensitive macroinvertebrate species have been recorded from the region previously (in 2015 and 2010) but were not found at the sampled sites in 2020. These included the waterbug (Hydrometra), damselfly (Nososticta solida), dytiscid beetles (Laccophilus sharpi), and several caddisflies (Ethochorema hesperium, Orthotrichia bishopi, Notalina fulva, and Triplectides volda).
Previous sampling of streams from the Eastern Mount Lofty Ranges from the mid-1990 to 2000s collected a number of additional rare, sensitive and uncommon species that have not been recorded from the region during the past two decades. They include a mite (Rhynchaustrobates bandus); beetles (Sclerocyphon and Simsonia); mayfly (Centroptilum elongatum); stonefly (Newmanoperla thoreyi); caddisflies (Apsilochorema, Maydenoptila rupina, Hydroptila calcara, Hydroptila losida, Hydroptila scamandra, Oxyethira columba and Triaenodes); chironomids (Podonomopsis, Podonomus, Aphroteniella, Coelopynia pruinosa, Rheocricotopus, Gymnometriocnemus, Stempellina and Xenochironomus); dragonfly (Austrogomphus australis); lacewing (Austroneurorthus); subterranean crustacean from the Family Parabathynellidae; and freshwater crab (Amarinus lacustris) which is more commonly found in the lower River Murray main channel, Lower Lakes and many coastal lakes in the South East.
The only fish seen or collected during sampling in 2020 were a Big-headed Gudgeon at a site on the Finniss River, and introduced Mosquitofish from the same Finniss River site and Rodwell Creek. Previous sampling in the region has also recorded Mountain Galaxias (Galaxias olidus) in the Finniss River catchment in 2015 and Climbing Galaxias (Galaxias brevipinnis) in 2010. More comprehensive fish surveys in the region have noted the presence of the threatened Yarra Pygmy Perch (Nannoperca obscura), Southern Pygmy Perch (Nannoperca australis) and River Blackfish (Gadopsis marmoratus) from a number of major stream reaches (see Hammer 2009).
Pressures and management responses
Pressures
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Management responses
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Bushfires causing widespread property and habitat damage to national parks and reserves
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Opportunistic prescribed burns in national and conservation parks when conditions are suitable remains the only realistic regional management action possible to address this pressure. The Department for Environment and Water coordinate these actions in partnership with other organisations, including Landscape SA Hills and Fleurieu and the Country Fire Service.
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Widespread introduced weeds in the riparian zone at some sites
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Green Adelaide and Landscape SA Hills and Fleurieu and Fleurieu continues to support several pest plant (weed) mitigation and control programs. They work closely with landholders, including local government, to control weeds on their property and to help stop the spread to other properties and waterways.
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Livestock having direct access at some sites (causing sediment erosion and adding excessive nutrients)
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Landscape SA Hills and Fleurieu land management program encourages and promotes managing land to improve water quality. This includes incentives for waterway (eg stream and creek) and wetland fencing to exclude or limit stock from entering riparian zones.
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Limited riparian zone vegetation at some creeks (reducing habitat quality, increasing sediment erosion)
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Landscape SA Hills and Fleurieu land management program encourages and promotes managing land to improve water quality. This includes incentives for revegetation programs around waterways and wetlands and stock exclusion as well as educating landholders about the importance of riparian vegetation in managing soil erosion. The Board also partner with local government to deliver a number of watercourse revegetation projects across the region.
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Stormwater runoff containing high nutrient and sediment loads discharging to some creek (causing habitat disturbance, algal growth and aquatic weeds)
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Green Adelaide and Landscape SA Hills and Fleurieu has a well-developed stormwater quality improvement, harvesting and reuse program which has installed (and maintains) gross pollutant (and silt) traps in several watercourses across the region to catch litter, debris and silt in order to minimise impacts and damage to seagrass and reef ecosystems in the receiving marine environment. Stormwater captured is also treated through artificial wetlands across the region which act as suspended solid and nutrient filters; these wetlands also provide important habitat for many native species.
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Nutrient inputs to some creeks from numerous diffuse sources (potentially leading to excess growth of algae and aquatic weeds)
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Landscape SA Hills and Fleurieu land management program encourages and promotes managing land to improve water quality. This includes working with industry and landholders to ensure efficient use of fertilisers and discuss ways to reduce runoff of nutrients into waterways.
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Further information
Dooley T & C Henschke 2000, Dryland Salinity Management within the Eastern Hills and Murray Plains LAP Area, PIRSA Rural Solutions technical report produced for the Eastern Hills and Murray Plains Catchment Group Inc.
EPA 2008, The State of Our Environment, South Australia 2008, Environment Protection Authority, South Australia.
Hammer M 2009, Freshwater Fish Monitoring in the Eastern Mount Lofty Ranges: Environmental Water Requirement and Tributary Condition Reporting for 2008 and 2009, Report to the South Australian Murray–Darling Basin Natural Resources Management Board, Adelaide.
Kefford BJ, Marchant R, Schafer RB, Metzeling L, Dunlop JE, Choy SC & P Goonan 2011, 'The definition of species richness used by species sensitivity distributions approximates observed effects of salinity on stream macroinvertebrates', Environmental Pollution 159: 302–310.
McEvoy P & P Goonan 2003, 'Salinity is not necessarily bad for biodiversity: case studies of invertebrates from South Australian streams and River Murray wetlands', Records of the South Australian Museum Monograph Series No. 7: 131–134.
O’Connor P, Morgan A & A Bond 2008, Bushbids: Biodiversity Stewardship in the Eastern Mount Lofty Ranges, South Australia, Australian Government and South Australian Murray–Darling Basin Natural Resources Management Board.