Wild Dog Creek, 5.5 km north-east from Yankalilla
2011 Aquatic Ecosystem Condition Report
- Permanently wet, moderately freshwater creek in autumn and spring 2011
- Moderately diverse macroinvertebrate community with a few rare and sensitive species
- Obvious signs of moderate to gross nutrient enrichment
- Riparian vegetation dominated by introduced grasses and weeds under a few gums.
About the location
Wild Dog Creek is a small stream in the Southern Mount Lofty Ranges that rises in and around the Myponga Conservation Park and flows in a north-westerly direction before discharging into Carrickalinga Creek, a few kilometres west from Carrickalinga. The monitoring site was located off Wild Dog Road, about 5 km ENE from Yankalilla on the Fleurieu Peninsula. The major land uses in the 2,185 hectare catchment are stock grazing and remnant native vegetation, with smaller areas included in the conservation park or used for irrigating grasses, cereal cropping, forestry, rural residential living and roads.
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 including nutrient enrichment, degraded riparian vegetation, fine sediment deposition and bank erosion caused by stock damage. Despite this, the stream still provided habitat for some rare and sensitive macroinvertebrate species.
A moderately diverse community of at least 35 species of macroinvertebrates was collected from the creek, 3.2-3.4 m wide and up to 53 cm deep, in autumn and spring 2011. The creek consisted of a non-flowing channel in autumn but was slightly flowing when sampled again in spring. The community was dominated by generalists and species tolerant to poor water quality such as amphipods (Austrochiltonia) and small baetid mayflies (probably Cloeon). It also included smaller numbers of limpets, native and introduced snails, worms, mites, isopods, freshwater shrimp, yabbies, beetles, mosquitoes, biting midges, chironomids, leptophlebiid mayflies, waterbugs, stoneflies and caddisflies. A few rare and sensitive rare species that are normally associated with flowing habitats were collected, including a mayfly (Thraulophlebia inconspicua), stonefly (Austrocerca tasmanica) and caddisfly (Triplectides similis). The site also provided habitat for several uncommonly collected mites (e.g. Hydryphantes, Koenikea and Arrenurus). No fish were seen at the site in 2011.
The water was moderately fresh (salinity ranged from 1,064-1,616 mg/L), well oxygenated (66-125% saturated), slightly turbid and coloured, and with moderate to high concentrations of nutrients such as nitrogen (0.68-1.63 mg/L) and phosphorus (0.02-0.15 mg/L).
The sediments were dominated by detritus and sand, with silt, clay, gravel and algae also present. Samples taken from below the surface were sulfidic which indicates that the sediments were anaerobic and lacked oxygen. A large deposit of silt, 1-5 cm deep, covered the creekbed in spring and at least 10 m of bank showed evidence of erosion due to cattle damaging the edges of the stream.
About 10% of the channel was covered by filamentous algae (mostly Cladophora and Spirogyra) in spring, when aquatic plants were growing prolifically and covered over 35% of the creek. A range of emergent species were recorded, including sedges (Cyperus), rushes (Juncus), reeds (Phragmites), dock (Rumex) and introduced watercress (Rorippa). The narrow riparian zone was dominated by introduced grasses and blackberries, bracken, reeds, sedges, rushes and a few scattered gum trees. The surrounding vegetation was mostly cattle and horse grazing paddocks with some scattered gum trees and bracken in the local landscape.
Special environmental features
The creek provides permanent aquatic habitats that support a range of macroinvertebrates, including a few rare and sensitive species.
Pressures and management responses
|Insufficient natural water flows in the creek resulting from water extraction and climate variability (reducing ecological integrity).||Through water allocation planning the Adelaide and Mount Lofty Ranges NRM Board seeks to manage a sustainable water supply for the region so that there is enough water available for everyone (including the environment) even in drought conditions.|
|Widespread introduced weeds in the riparian zone at the site and upstream (reducing habitat quality).||The Adelaide and Mount Lofty Ranges NRM Board has several pest plant (weed) mitigation and control programs. They work closely with landholders to control weeds on their property and to help stop the spread to other properties and waterways.|
|Livestock having direct access at the site and upstream (causing sediment erosion and adding excessive nutrients).||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for waterway and wetland fencing to exclude or limit stock from entering riparian zones.|
|Limited riparian zone vegetation at the creek and upstream (reducing habitat quality, increasing sediment erosion).||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes incentives for revegetation programs around waterways and wetlands and stock exclusion as well as educating landholders about the importance of riparian vegetation in managing soil erosion.|
This aquatic ecosystem condition report is based on monitoring data collected by the EPA. It was prepared with and co-funded by the Adelaide and Mount Lofty Ranges NRM Board.