Eyre Peninsula Landscape Regional Summary
2020 Aquatic Ecosystem Condition Report
A total of 3 sites from the Tod River were sampled from the region during spring 2020, to record how the stream has recovered following the extensive bushfire in the region in 2005. Sites from White Flat and Koppio occurred within the burnt area and a site further upstream near Yallunda was outside the bushfire zone. Land use surrounding each site comprised agriculture (grazing and cropping) and smaller patches of remnant native vegetation.
- A total of 3 sites were sampled on the Tod River and each was rated in a Fair condition.
- Macroinvertebrate communities comprised a moderate diversity of generalist and saline tolerant species, with no rare or sensitive species recorded
- All sites were enriched with nutrients and saline (5–10,000 mg/L)
- Riparian zones comprised gums with rushes and weeds in the understory, and the adjacent land was used for cropping and grazing.
- Most streams on Eyre Peninsula were probably naturally saline prior to European settlement but have been further salinised by extensive vegetation clearance between the 1880s–1970s
Sites monitored from the Eyre Peninsula in 2020 were considered to be in a Fair condition, with moderate changes to animal and plant life, and some changes to the way the ecosystems functioned. In previous years, no site has been assessed in either an Excellent, Very Good or Good condition, and it is thought streams in these better condition classes probably no longer exist in the region given the scale of vegetation clearance, salinization and nutrient enrichment. However, some sites have been found in Poor and Very Poor condition on previous sampling occasions, so the Fair ratings for the Tod River sites are likely to be the best that can be expected for the Eyre Peninsula.
Salinity is a major issue on Eyre Peninsula with most streams considered to be saline (eg salinity >3,000 mg/L). In 2010, only Poonana and Yeldulknie creeks near Cleve and Coonta Creek near Tumby Bay were fresher (salinity between 1,000-3,000 mg/L), and all sampled sites in 2015 were saline. The Tod River is among the least saline streams in the region but still had a salinity ranging between 5–10,000 mg/L in 2020.
All sites showed evidence of significant nutrient enrichment, including high median concentrations of nitrogen (1.7 mg/L) and phosphorus (0.16 mg/L), and large algal biomass measurements (42 µg/L chlorophyll) and moderate aquatic plant growths (ie >10% stream channels covered in plants) recorded from the sampled sites. Surface runoff from agricultural lands were significant stressors affecting the condition of these sites but there were no indications of lasting impacts from the 2005 bushfire on the White Flat or Koppio sediment, water quality or biological communitiese. Riparian zones extended over 40 m wide in places, comprising gums or rushes, sedges and a range of introduced grasses and weedy species. Away from the river, the land was used for cropping and sheep grazing.
The moderately diverse aquatic macroinvertebrate communities were dominated by a few generalist and saline tolerant species, and no site sampled supported any rare or sensitive species. An amphipod crustacean (Austrochiltonia australis) was usually the most abundant macroinvertebrate, along with chironomids (Procladius, Chironomus, Tanytarsus, Dicrotendipes, Cladopelma and Paralimnophyes), waterbugs (Anisops, Agraptocorixa, Sigara and Microvelia), snails (Potamopyrgus) and damselflies (Coenagrionidae). Smaller numbers of nematodes, worms, various mites, beetles, biting midges, soldierflies, caddisflies, dragonflies and yabbies were also collected. The lack of sensitive groups such as mayflies and stoneflies and the lack of flow-dependent species, highlights the absence of flowing, freshwater habitats in the river and broader region.
Special environmental features
No rare or sensitive species were found in the region in 2020, which is consistent with previous sampling conducted on Eyre Peninsula. No flow-dependent species were recorded but in previous years, saline-tolerant species such as a blackfly (Simulium ornatipes) and hydropsychid caddisfly (Cheumatopsyche) have been collected from flowing habitats called riffles. The region is notable due to the lack of many groups of macroinvertebrates that are commonly found in freshwater streams from the other southern parts of South Australia, including bivalve molluscs, shrimps, prawns, mayflies, stoneflies, and a richer diversity of dipterans and caddisflies.
No fish were collected from the Tod River in 2020. However, Mosquitofish, hardyheads, Galaxias maculatus and Western Blue-spotted Gobies have been recorded from the region in previous years, and the threatened Climbing Galaxias (Galaxias brevipinnis) was recorded from the Tod River, near Whites Flat, in 2010.
Previous sampling on Eyre Peninsula since mid-1990s has included several rare and uncommon species that have not been since. They include a subterranean crustacean (Family Parabathynellidae), a mayfly (Cloeon), two beetles (Copelatus and Paroster), three chironomids (Botryocladius grape 'th', Apsectrotanypus and Paraheptagyia), a biting midge (Atrichopogon), 3 caddisflies (Ecnomus cygnitus, Hellyethira simplex and Oecetis) and the water measurer (Hydrometra). Most of these records came from either the Tod River catchment, Coonta or Yeldulknie creeks.
Pressures and management responses
Livestock having direct access to streams and upstream riparian zones in the catchment, causing sediment erosion and adding excessive nutrients.
Landscape SA Eyre Peninsula administers the water affecting activities permits and polices for the region. This process allows the Board to grant or refuse permits to undertake certain activities affecting water resources. The process is the region’s primary means of preventing any potential impact on the environmental integrity of surface water catchments.
In 2012 the Eyre Peninsula NRM Board delivered a project titled Delivering the Requirements of the Tod River Management Plan. This project implemented recommendations outlined in the River Management Plan for the Tod Catchment, as well as the Freshwater Fish Survey of Southern Eyre Peninsula baseline report. In doing so, the project protected and enhanced over 380 ha of native habitat identified as having high conservation value. This was achieved primarily by reducing pressures on degraded areas through removal of livestock, enhancing remnant vegetation, re-establishing native vegetation, and control of invasive Weeds of National Signifiance (WoNS). In addition, 2 fish-friendly watercourse crossings were constructed which has helped improve the hydrology of 2 highly significant sections of the Tod River, while greatly improving the ability for native fish and other aquatic biota to migrate unimpeded.
Land salinisation and limited natural riparian vegetation at sites and upstream in the catchment, providing minimal buffer protection from catchment land uses.
Landscape SA Eyre Peninsula continues to promote managing land to improve water quality. This includes incentives for:
Dooley T, Henschke C & P Ciganovic 2001, Dryland Salinity Management within the Salt Creek Catchment (on Lower Eyre Peninsula), technical report produced for the Salt Creek Catchment Steering Committee, PIRSA Rural Solutions.
Dooley T & C Henschke 2000, Dryland Salinity Management in the Tod River Catchment, report to the Tod River Catchment Landcare Group as part of the NHT Catchments Back in Balance Project.
E & WS1984, Eyre Peninsula Water Resources Management Review, Engineering and Water Supply Department, Library Reference Number 83/45.
Henschke C & P Ciganovic 2004, Yeldulknie Catchment Salinity Management Plan, Rural Solutions SA.
Henschke C, Dooley T & P Ciganovic 2002, Dutton River and Byrne Bay Salinity Management Plan, Primary Industries and Resources SA.
Jolly I, Walker G, Stace P, van der Wel B & R Leaney 2000, Assessing the Impacts of Dryland Salinity on South Australia’s Water Resources, CSIRO Land and Water Technical Report 9/00, March 2000.
Shepherd RG 1985, ‘Hydrology Chapter 7’ in Natural History of Eyre Peninsula, editors Twidale CR, Tyler MJ & M Davies), Royal Society of South Australia (Inc).
Twidale CR & EM Campbell 1985, ‘History of exploration and settlement. Chapter 1’ in Natural History of Eyre Peninsula, editors Twidale CR, Tyler MJ & M Davies, Royal Society of South Australia (Inc).