Protecting mussels in your stream
Complex stream channels with large logs embedded in the channel stabilise the stream bed and provide a flood refuge for mussels. A dense tree and shrub canopy provides shade and protects stream banks from erosion while mat-rush (Lomandra longifolia) protects the stream banks from scour.
Photo: Kerry Wilson.
Landholders can help to protect and improve freshwater mussel habitats by:
- restricting stock access to streams
- establishing filter strips
- revegetating stream banks and controlling weeds
- restoring instream habitats
- working with neighbours to rehabilitate long sections of stream.
Landholders should seek professional advice from their local catchment management authority (CMA) before starting restoration work, particularly if you are planning instream works, as there are legal issues to be considered. CMA officers can help you assess, plan and implement a riparian land management program. This will improve the chances of success of your project. CMAs may also provide funding to support landholders and community groups.
Protecting riparian lands from domestic stock gives trees and shrubs a chance to regenerate and protects streambanks from erosion. A dense groundcover will also develop over time. Riparian vegetation protects streambanks from erosion and, in the long term, will return large snags to the stream, increasing habitat for mussels. The shade provided by trees lining the channel also helps to regulate water temperatures and stabilises dissolved oxygen levels.
The positioning and type of fencing, and placement of water points requires careful planning. Conventional fencing is vulnerable to flood damage although a range of fencing options exist that greatly reduce this risk. Consider providing off-stream watering points for stock or limiting access to selected areas to minimise erosion damage and water pollution.
Filter strips combined with a well-developed native riparian zone will reduce siltation and nutrient loads. The most effective filter strips are a dense groundcover of spreading grasses that are at least 10-15 cm high. Buffers should be widest at gullies and other low points in the landscape where water tends to pool before entering the stream. The optimal width of the filter strip will vary with slope, soil, rainfall and the size of the stream.
Replanting of degraded streambanks with collected seed or tube stock is sometimes necessary to restore riparian vegetation. A range of plant species should be introduced because different species perform different functions in preventing erosion. It will also help to establish a multi-layered canopy. The success of restoration efforts depends on ongoing maintenance, especially in areas with fierce weed competition. Plant from the top of the bank to as near to the base of the streambank as possible. Plants with flexible stems or a dense canopy will protect the bank from the scouring action of water.
Restoring instream habitats. Careful placement of boulders, large snags or engineered log jams in stream channels stabilise the stream bed and recreate microhabitats for mussels by providing refuges during floods and reducing bed mobility. Some types of stream erosion need to be addressed by bed control structures or bank stabilisation works. In small sandbed streams, large woody debris is critical to maintain streambed stability and habitat structure. Instream remediation actions are specialised, often expensive, and have to be undertaken under the direction of the CMA.
Conservation actions will be more effective if neighbouring landowners band together to restore habitats along a whole reach of stream. Restoration efforts at this scale are required to stabilise stream temperatures or make meaningful reductions in nutrient loads.
A series of fact sheets dealing with management of riparian land and instream habitats are available from the former Land & Water Australia. They provide detailed discussions of river management issues and solutions. Most of them are freely available online in pdf format.
Find out more about Freshwater mussels of coastal NSW
Page last updated: 19 June 2011