Tributary of Western River, Near Snug Cover Road
2013 Aquatic Ecosystem Condition Report
- Dry in autumn and spring 2013
- Unlikely to be nutrient enriched when wet due to the extent of forestry in the catchment but there was evidence of the mobilisation of fine sediments within the channel following winter flows
- No evidence of any bank erosion or stock accessing the site
- Riparian vegetation consisted of Blue Gum forest
About the location
Tributary of Western River is a very small first order stream that rises at an elevation of about 250 m at the most upstream reach of the South Branch of the Western River. The major land-use in the 24 hectare catchment upstream from the site sampled was plantation forestry (95%), with minor areas used for other minimal uses and dams. The site was located among a blue gum forestry plantation off Snug Cove Road, about 42 km north-west from Parndana.
Kangaroo Island NRM Regional Summary 2013
The creek was given a Fair rating because the site sampled showed evidence of moderate changes in ecosystem structure and some changes to the way the ecosystem functions. There was evidence of human disturbance due to the lack of remnant native vegetation and extent of plantation forestry in the catchment of this first order tributary stream.
The 1-1.5 m wide channel was dry in both autumn and spring 2013. No macroinvertebrate or water quality data was consequently available for this site.
The sediments were dominated by detritus (60%) and sand (20%) in autumn but in spring, the proportion of sand increased to 50% cover, whereas detritus comprised about 30% of the in-stream sediment; smaller amounts of silt and clay were present during both surveys. This indicates that winter rains altered the composition of the sediments and led to the deposition of more sand within the channel in the vicinity of the site during 2013. Samples taken from below the surface were well-aerated grey sands that showed no evidence to indicate that the sediments had recently been been anaerobic or lacking in oxygen. There was no evidence of any significant bank erosion at the site and the only animal droppings seen near the creekbed were from kangaroos.
There was no evidence of any dried filamentous algal mats on the dry sediments of the creek and the only aquatic plant seen at the site were a few rushes (Juncus), which covered less than 10% of channel. The riparian zone was indistinct because blue gums extended from the banks into the surrounding landscape. The tree cover from the adjacent Blue Gum Forest near the creekline was so extensive that it shaded about 90% of the riparian zone and channel.
Special environmental features
Pressures and management responses
|Altered flow regime in the creek resulting from extensive plantation forestry (reducing ecological integrity).||The Kangaroo Island Regional NRM Plan includes a target to address surface water flow management.|
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