09082: Protecting and restoring freshwater ecosystem health in the Serpentine River, an adaptive management approach
Freshwater mussels have important roles to play in river health. They feed by sucking water in through their 'inhalent siphon' and filtering out microscopic plankton, algae, bacteria and plant debris through their gills. They release clean, fresh water through their 'exhalent siphon'.
Some scientists believe they have an especially important role in keeping a good standard of water quality in pools where freshwater fish retreat to over the dry, hot summer periods.
The Serpentine River is home to Westralunio carteri, the only native freshwater mussel in south-west WA. Survival and success of the mussel relies heavily on the presence of native freshwater fish species, including the western pygmy perch, nightfish, and western minnow.
Feral fish out-compete and consume native freshwater fish upon which mussel larvae attach to move to new parts of the river and establish new colonies. Survival of the mussel is also affected by habitat disturbance including:
- bank erosion, which increases sediment load and water turbidity, affecting the prey density of invertebrates
- eutrophication, which leads to algal blooms that limit oxygen availability.
This project will conduct on-ground works and monitoring of freshwater mussel and fish populations and their preferred habitats within a variety of riparian zones along the Serpentine River within Bush Forever site 368. The upstream end of the project area includes near pristine, heavily vegetated watercourse within native forest. The downstream portion includes partially revegetated watercourse in farmland and an area that has been converted into an agricultural drainage system and is subject to higher disturbance, livestock and urban pollutant impacts.
The intended goal is to protect and enhance the health of the pristine reach as it runs through native forest and recover the health of the impacted reach. This will involve:
- Baseline monitoring of water quality, fish species composition and mussel population size and their life cycles in both sections of the river.
- On-ground works in the impacted reach to eradicate feral fish, identify impacts of livestock, and appropriate riparian flora to revegetate the streamline.
Continued monitoring to measure the success of these on-ground works and adjust if necessary, following an adaptive management process to refine waterways management.
|Investment:||$ 18 700|
|In-kind contribution:||$ 25 645|
|Other contribution:||$ 3 145|
|Delivery organisation:||Serpentine River Group; Lowlands Conservation Association|
|Project duration:||June 2010 - September 2011|
|Location:||Serpentine River, Shire of Serpentine Jarrahdale|
Major project achievements
- Water quality, fish species composition and mussel population size in both sections of the river assessed to help determine river health.
- Preferred habitats of freshwater mussels identified.
- Freshwater mussel life cycle and host fish species required for larval mussel development determined.
- Feral fish species and other significant predator species removed.
- Plans created to improve river health through agricultural land adaptations.
Serpentine River Group; Lowlands Conservation Association; Murdoch University; Serpentine Jarrahdale Landcare Inc.; Shire of Serpentine Jarrahdale