Timber Creek, SE Parndana
2008 Aquatic Ecosystem Condition Report
- Significantly affected by high salinity levels and nutrient enrichment.
- Macroinvertebrate community lacked diversity.
- No sensitive or rare species found.
- Provides habitat for a notable species of saline tolerant beetle.
About the location
Timber Creek rises to the east of Parndana in the middle of Kangaroo Island and flows southeast into Murray Lagoon, in the Cape Gantheaume Conservation Park. Most of the catchment area is used for livestock grazing and cropping, with some forestry and rural living. There are large areas of remnant native vegetation in the mid to upper reaches of the creek.
The site selected for monitoring was located in the lower reaches of the creek off South Road, about 20 km southeast of Parndana.
The creek was given a poor rating at this site because the ecosystem showed evidence of major changes in the animal community and plant life, and moderate changes to the way the ecosystem functions due to high salinity levels and nutrient enrichment.
The creek consisted of shallow, connected pool habitats when it was sampled in December 2008.
Only 20 species of macroinvertebrates were found at the site. Large numbers of species tolerant to high salinity and nutrient levels dominated the community, particularly the tiny crustacean, water scud (Austrochiltonia australis), and chironomids (Tanytarsus and Procladius). No sensitive or rare species were collected.
The water was saline (13,500 mg/L) and moderately well oxygenated (46% saturation). It was also coloured and slightly cloudy, or turbid, with moderate to high concentrations of nutrients such as nitrogen (1.7 mg/L), phosphorus (0.08 mg/L) and organic carbon (26.4 mg/L). Large amounts of phytoplankton were suspended in the water but, surprisingly, no green filamentous algae or other aquatic plants were found.
The riparian zone formed a well vegetated strip between 10 and 30 metres wide along the creekline. Gums, acacias and other native trees and shrubs grew over samphire and introduced grasses. Pasture grasses covered most of the surrounding area, with patches of low-growing native woodland beside the road.
Special environmental features
This creek provides habitat for an uncommonly collected, saline tolerant Scavenger Water Beetle (Limnoxenus zealandicus) from the Family Hydrophilidae.
Pressures and management responses
|Limited riparian zone vegetation at the site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||The Kangaroo Island NRM Board has funded the fencing and re-vegetation of significant areas of riparian vegetation in the catchment and continues to work with landowners to increase the presence of protected riparian vegetation by funding the fencing of watercourses.|
|Altered flow regime resulting from catchment clearing or modification (reducing ecological integrity).||The Kangaroo Island NRM Board have adopted policies to ensure the sustainable water use limits of the catchment are not exceeded.|
|Saline groundwater inflow (reducing ecological integrity).||The Regional NRM Plan includes a target to address saline groundwater.|