Meadows Creek, near North Shields
2010 Aquatic Ecosystem Condition Report
- Permanent slow-flowing saline creek with water present in both autumn and spring.
- Diverse macroinvertebrate community with no rare or sensitive species.
- Obvious signs of moderate nutrient enrichment.
- Riparian vegetation limited to crops and grasses.
About the location
Meadows Creek is a small stream in Eyre Peninsula. It rises near Charlton Springs and flows east where it eventually enters the estuarine reaches of the Tod River before discharging into Spencer Gulf at Louth Bay. The major land uses are sheep grazing and cropping.
The monitoring site was located off the Lincoln Highway, over three kilometres north of North Shields.
The creek was given a Fair rating because the site sampled showed moderate changes in ecosystem structure and some changes to the way the ecosystem functions. There was evidence of human disturbance, including nutrient enrichment, poor riparian habitat and fine sediment deposition, although the stream still provided an important refuge for a wide range of macroinvertebrate species.
A diverse community of at least 40 species of macroinvertebrates was collected from this slow-flowing creek, five metres wide and up to 57 centimetres deep, in autumn and spring 2010. The community was dominated by large numbers of generalists and species tolerant to poor water quality such as chironomids, amphipods, caddisflies, waterbugs and dragonfly nymphs. The only non-insects collected were a mite and two types of crustaceans. The insects included at least 11 species of beetles, three mosquitoes, a soldierfly, six chironomids, six waterbugs, six odonates and three species of leptocerid caddisflies. No sensitive or rare species were found despite the wide diversity of species present at the site.
The water was saline (salinity of 6,300 mg/L in autumn and 4,988 mg/L in spring), well oxygenated (86-124% saturation), slightly turbid and coloured, with moderate to high concentrations of nutrients such as nitrogen (1.11-2.71 mg/L) and phosphorus (0.02-0.05 mg/L).
The sediments were dominated by detritus, with smaller amounts of silt, clay, cobbles and algae also present. Samples of sediment taken from below the surface were sulphidic, indicating that the decomposition of organic matter was depleting the sediments of oxygen and turning them anaerobic. A moderately thick deposit of 1-5 centimetres of silt was also present in the channel in spring, possibly caused by runoff from the surrounding agricultural land and sheep accessing the stream earlier in the year.
Filamentous algae (Enteromorpha) covered more than 10% of the site in spring and a range of emergent aquatic plants (Bolboschoenus, Cyperus, Polygonum and Juncus) covered less than 10% of the site in both autumn and spring. The riparian zone was very narrow and limited to introduced grasses and some rushes and sedges. Cereal cropping occurred up to the water’s edge in places and there were no native trees or shrubs present in the surrounding landscape other than remnants as part of the roadside vegetation.
Special environmental features
Meadows Creek provides habitat for a diverse range of macroinvertebrates in the region despite its high salinity.
Pressures and management responses
|Livestock have direct access at the site and upstream in the catchment, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds)||
The Eyre Peninsula NRM Board promotes managing land to improve water quality. This includes incentives for:
|Limited natural riparian vegetation at the site and upstream in the catchment, providing minimal buffer protection from catchment landuses (reducing habitat quality)|
|Saline groundwater inflow (reducing ecological integrity)||The Eyre Peninsula NRM Board promotes the revegetation of recharge areas known to contribute to dryland salinity and encourages the adoption of perennial pastures as an alternative to annual cropping in these areas.|
|Insufficient natural water flows (reducing ecological integrity)||The Eyre Peninsula NRM Board water resources program regulates the diversion of water from priority catchments on Eyre Peninsula.|