Yeldulknie Creek, near Cleve
2010 Aquatic Ecosystem Condition Report
- Dry in autumn and shallow, isolated pools present in spring.
- Sparse macroinvertebrate community with no rare or sensitive species.
- Signs of moderate to gross nutrient enrichment.
- Riparian vegetation was very limited and dominated by sedges and grasses.
About the location
Yeldulknie Creek is a small stream in Eyre Peninsula. It rises within the Yeldulknie Conservation Park and flows south into the now disused Yeldulknie Reservoir. Further downstream the largely dry creek meanders south where it eventually drains into an intermittent swamp on the Twelve Mile Plain, several kilometres north from Arno Bay. The major land uses are native vegetation, water storage, grazing and recreation near the site sampled.
The monitoring site was located downstream of the Yeldulknie Reservoir off Yeldulknie Road, over four kilometres east of Cleve.
The creek was given a Poor rating because the site sampled showed evidence of major changes in ecosystem structure and moderate changes to the way the ecosystem functions. There was considerable evidence of human disturbance, including reduced flows due to its capture in the reservoir, nutrient enrichment effects and a lack of vegetative cover in the riparian zone.
A sparse community of about 21 species of macroinvertebrates was collected from the isolated pools in the creek, five metres wide and 20 centimetres deep, in spring 2010; the site was dry in autumn. The community was dominated by species tolerant to poor water quality, including chironomids, leptocerid caddisflies (Triplectides), damselflies and corixid waterbugs (Agraptocorixa). It also included smaller numbers of mites, beetles, mosquitoes, soldierflies, notonectid waterbugs and dragonflies. No sensitive or rare species were found.
The water was moderately fresh (salinity of 2,863 mg/L), well oxygenated (110% saturation) and clear, with moderate to high concentrations of nutrients such as nitrogen (1.0 mg/L) and phosphorus (0.02 mg/L).
The sediments were dominated by detritus, gravel and sand, with some pebbles, cobbles and boulders also present. Samples taken from below the surface were not obviously sulfidic, however, the underside of rocks were black in places, indicating that the stream had been anaerobic in the past.
A moderate amount of phytoplankton was recorded from the creek but filamentous algae was not evident in 2010. More than 10% of the site was covered by emergent aquatic plants such as sedges (Cyperus) and rushes (Juncus).
The riparian zone was very narrow and consisted of sedges, saltbush, kangaroo grass, introduced grasses and weeds. The surrounding vegetation at the site was mostly acacias and gum trees over introduced grasses.
Special environmental features
Yeldulknie Creek was one of only three moderately freshwater streams that were sampled from the region in 2010.
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).|
|Insufficient natural water flows (reducing ecological integrity).||The Eyre Peninsula NRM Board's water resources program regulates the diversion of water from priority catchments on Eyre Peninsula.|
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