Tanunda Creek, near Bethany
2008 Aquatic Ecosystem Condition Report
- Significantly affected by high nutrient levels and reduced flows.
- Macroinvertebrate community dominated by species tolerant of pollution.
- Streambanks eroded by livestock.
- Provides habitat for at least two common frog species.
About the location
Tanunda Creek is a small stream which rises in the Kaiserstuhl Conservation Park in the Barossa Valley and flows occasionally, draining west towards Bethany before disappearing underground in the North Para River catchment. Apart from the conservation park, major land uses in the area include cattle grazing, cereal cropping and vines.
The site selected for monitoring was located off Gravel Pit Road, four kilometres east of Bethany.
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 nutrient levels and limited flows.
Disconnected pools of shallow water formed the creek at this site when it was sampled in November 2008.
A moderately diverse community of 30 macroinvertebrate species was collected, including numerous insects such as flies, waterbugs, beetles and odonates that frequently colonise temporary streams. Flatworms, roundworms, snails and crustaceans that can survive when streams dry up for some of the time were also found. The community was dominated by moderate numbers of snails (Glyptophysa concinna) and worms, which are tolerant to poor water quality. No sensitive or rare species were collected.
The water was moderately fresh (salinity of 1,000 mg/L), poorly oxygenated (39% saturation) and cloudy, or turbid. It contained very high concentrations of nutrients such as nitrogen (4.8 mg/L), phosphorus (0.5 mg/L) and organic carbon (43 mg/L). Large amounts of phytoplankton were also found.
Patches of small spikerush (Eleocharis) and rush (Juncus) grew in the channel, and moderate growths of green filamentous algae (Cladophora) were found on the surface of some pools.
River Red Gums grew over introduced grasses and weeds along the riparian zone, while cereal cropping occurred over most of the surrounding area.
Special environmental features
The creek provides habitat to two common frog species, the Marsh Frog (Limnodynastes tasmaniensis) and Common Froglet (Crinia signifera).
Pressures and management responses
|Livestock have direct access at the site and upstream, causing sediment erosion and adding excessive nutrients (which leads to habitat disturbance, algal growth and aquatic weeds).||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 site and upstream, providing minimal buffer protection from catchment landuses (reducing habitat quality).||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.|
|Large decrease in natural water flows (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.|
|Large nutrient inputs from numerous diffuse sources in the catchment (leading to extensive growth of algae and aquatic weeds).||The Adelaide and Mount Lofty Ranges NRM Board’s land management program encourages and promotes managing land to improve water quality. This includes working with industry and landholders to ensure efficient use of fertilisers and discuss ways to reduce runoff of nutrients into waterways.|
This aquatic ecosystem condition report is based on monitoring data collected by the EPA and prepared in conjunction with the Adelaide and Mount Lofty Ranges NRM Board.