Northern and Yorke Landscape Region
2021 Aquatic Ecosystem Condition Report
A total of 5 sites were sampled from streams in the Barossa Valley and 5 sites from in or near the Clare Valley within the Northern and Yorke Landscape SA region. Land use is dominated by agricultural stock grazing, cereal cropping and vineyards, with only a small area of remnant native vegetation occurring in the region.
- 10% of sites in Good condition rating, 60% in Fair condition and 30% in Poor condition.
- The only stream in Good condition was Jacob Creek at the Kaiserstuhl gauge station, notable due to the presence of many rare, sensitive and flow dependent macroinvertebrates, and minor evidence of nutrient enrichment.
- The 6 sites rated in Fair condition were located on the North Para River at Penrice, Mt McKenzie and Gomersal Rd, and Hutt River, Skillogallee Creek and the Wakefield River at Woolshed Flat. These sites were characterised by macroinvertebrate communities, lacked rare and sensitive species, and were dominated by generalist and tolerant species. The streams also generally had more degraded riparian habitats and showed clear evidence of nutrient enrichment.
- The sites in Poor condition included Greenock Creek, Eyre Creek and Wakefield River at Riley’s. These sites provided habitat for tolerant and generalist macroinvertebrates, were typically more saline, had limited riparian habitats, and showed signs of being overwhelmed by plant and algal growths when wet.
- Best land management practices do not appear to have been widely and consistently implemented at the reach or sub-catchment scale, and much remains to be done to eradicate riparian weeds and reduce the movement of nutrients and fine sediment into streams throughout the region.
According to the Bureau of Meteorology, a slightly lower than average rainfall was recorded across the state in 2021, with a very dry September but the wettest November on record. The mean annual temperature was 0.36°C above average. Consequently, when samples were taken from the region in late November–early December, stream conditions should have represented typical, well-watered conditions for the sampled sites.
Sites monitored in spring 2021 were considered to be in a Good to Poor condition. No sites were assigned to the Excellent, Very Good or Very Poor classes. Given the scale of vegetation clearance, it is unrealistic to expect any stream to be unaffected by human activities.
Of the sites assessed, 1 site (10%) was in Good condition with only minor changes to animal and plant life, 6 sites (60%) were in Fair condition with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned, and 3 sites (30%) were in Poor condition with moderate changes to the way ecosystems functioned.
The best site was located in the mid-reaches of Jacob Creek which was well-lined by vegetation and supported at least 52 macroinvertebrate species from flowing and stillwater habitats. The stream had a salinity of about 880 mg/L when sampled.
In contrast, the more degraded sites assigned to the Fair and Poor condition classes were from cleared agricultural catchments with little to no remnant native vegetation, macroinvertebrate communities dominated by 13–33 tolerant and generalist species, with limited riparian habitats and waters enriched with nutrients and fine sediment, and most with salinities well over 1,000 mg/L.
Aquatic macroinvertebrate communities were dominated by tolerant and generalist macroinvertebrate species, including an amphipod crustacean (Austrochiltonia), snails (introduced Physa and native Glyptophysa), chironomids (Procladius, Paramerina, Cricotopus, Paratanytarsus, Chironomus, Dicrotendipes and Polypedilum) and waterbugs (Micronecta, Microvelia, Sigara and Anisops). Most streams also supported lower numbers of flatworms, worms, shrimp and different damselflies and dragonfly larvae (eg Ischnura, Austrolestes, Hemianax and Hemicordulia).
Regionally significant species were only recorded from flowing water habitats at Jacob Creek, including riffle beetles (Family Psephenidae), trickle midges (Family Thaumaleidae), blackfly larvae (Austrosimilium), mayflies (Offadens, Atalophlebia, Thraulophlebia) and caddisflies (Ulmerochorema and Taschorema).
Other notable species found in riffle habitats from a few streams in the region included snails Angrobia and introduced Potamopyrgus), another blackfly species (Simulium) and a caddisfly (Cheumatopyche). These species require well-oxygenated, flowing water and, apart from the latter 2 species, do not occur in streams that rarely flow or are covered in algae, or with salinities over 3,000 mg/L.
Most streams in the region were distinguished by the presence of a narrow (<5 m up to 10 m wide) riparian zone comprising River Red Gums over weedy grasses. The exception was at Jacob Creek, which extended up to 30 m wide but also consisted of River Red Gums and weedy ash trees over woody weeds such as blackberries and gorse, and an understorey of weeds and introduced grasses.
Barossa Valley streams had chlorophyll concentrations ranging from 6–42 µg/L, nitrogen from 0.45–1.79 mg/L, phosphorus from 0.01–0.18 mg/L, and field conductivity from 1,464–4,717 µS/cm.
Clare Valley streams had lower chlorophyll a concentrations ranging from 4–8 µg/L, often lower nitrogen concentrations from 0.29–0.91 mg/L, sometimes higher phosphorus levels from 0.01–0.24 mg/L, and stream conductivity ranged from 310–26,310 µS/cm.
Special environmental features
The most notable record was the presence of the riffle beetle larvae Sclerocyphon (Family Psephenidae) and trickle fly larvae (Family Thaumaleidae) from Jacob Creek. Both species have been rarely collected in the Mount Lofty Ranges and have a restricted distribution to permanently flowing, less disturbed streams such as First and Sixth Creeks.
Previous work in the Barossa Valley has recorded similar species assemblages from Jacob Creek but few rare or sensitive species appear to inhabit the main channels of the North or South Para Rivers or other tributary streams.
Sites from the Clare Valley have not been assessed since 2008 but streams from the North Para River were last assessed as part of the Western Mount Lofty Ranges region in 2018.
Previous work in the Clare Valley noted that Mary Springs provided the most significant habitat for several notable species, including stoneflies (Dinotoperla evansi), mayflies (Atalophlebia, Nousia fuscula, Offadens) and caddisflies (Orphninotrichia maculata, Apsilochorema gisbum) that are more typically found in the cooler and more permanently flowing freshwater streams in the Southern Mount Lofty Ranges.
Previous sampling in the upper Skillogallee Creek during the 1990s also recorded mayflies (A. australasica and Thraulophlebia inconspicua) and caddisflies (Taschorema evansi). None of these species were recorded from the sampled streams in 2021, and given their apparent restricted distribution, it is possible that some may no longer occur in the Northern and Yorke Landscape region.
Pressures and management responses
Widespread introduced weeds in the riparian zone at some sites
The Northern and Yorke Landscape Board has 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.
Livestock having direct access at some sites (causing sediment erosion and adding excessive nutrients)
The Northern and Yorke Landscape Board’s 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.
Limited riparian zone vegetation at some creeks (reducing habitat quality, increasing sediment erosion)
The Northern and Yorke Landscape Board’s 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 partners with local government to deliver a number of watercourse revegetation projects across the region.
Nutrient inputs to some creeks from numerous diffuse sources (potentially leading to excess growth of algae and aquatic weeds)
The Northern and Yorke Landscape Board 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.