What is a wetland?
A wetland is an area that is inundated or waterlogged by surface or ground water, either permanently or seasonally. Wetlands have vegetation which is typically adapted for life in saturated soil conditions. Examples of wetlands include swamps, seeps, lakes and estuaries.
Wetlands in Torbay
There are a wide variety of wetland types in the Torbay catchment. These include the coastal lakes and basin wetlands, the palusplains that spread over the wide, flat land typical of the mid catchment along the South Coast Highway and the hillside seeps (paluslopes) of both the Karri hills and the northern country.
WHAT ROLE DO WETLANDS HAVE?
Wetlands are extremely important components of the landscape for water management. Wetlands collect, store and use water lost or transported from the surrounding landscape. The plants in and around the water help remove sediments and nutrients, thereby cleaning the water before it moves on to other areas or is used by native animals in the wetland.
Wetlands support a wide array of life, both aquatic and terrestrial. Birdlife is often abundant around wetlands, as they take advantage of the fish, crustaceans and macroinvertebrates which they feed upon. Wetlands are also breeding habitat for ducks, bitterns, crakes and rails in the fringing vegetation.
Wetlands of the South Coast have important aesthetic, recreational and agricultural values. They have been an important food and water source for Noongar people and today the fertile soils and water supply associated with many wetlands is used to grow vegetables and water livestock. Wetlands are culturally significant as recreational areas, places of great beauty which have spiritual significance for many people.
WHOSE RESPONSIBILITY IS IT TO MANAGE WETLANDS?
Human activities have had a significant impact on many wetlands on the south coast. Changes to drainage, recharge and runoff, as well as vegetation clearing and the input of additional nutrients (from synthetic fertilisers, animal manure and organic matter from soft leaved introduced plants), have led to the degradation of many wetlands. Therefore, it is important to manage our remaining wetlands so they will survive as functioning ecosystems.
Management of wetlands should take place at both the catchment and the local scale and may involve a number of groups or individuals. Catchment management may be undertaken by a government body, such as the Department of Water who regulate activities like groundwater extraction from bores, or undertaken in partnership with local community groups, such as the Torbay Catchment Group.
Some wetlands are managed by local government or the Department of Environment and Conservation (DEC) however, many wetlands are found on private property.
In this case it is the landowners responsibility to ensure their activities do not threaten the hydrology or biology of the wetland. Financial and technical assistance is available through a range of organisations to help better manage wetlands on private property.
Native vegetation is protected by law in Western Australia under the Environmental Protection Act 1986. Most types of clearing are prohibited unless a permit has been granted. The DEC manage the vegetation clearing permit system.
HOW DO I CARE FOR WETLANDS?
The amount of water and how long it is present is a major factor in determining how each wetland system operates. This is determined by causes such as surface run-off, rainfall and groundwater. Factors such as land clearing, artificial drainage, seasonal variation, climate change and the surrounding land uses will influence the amount of water entering and leaving the system.
In Torbay, drainage for agriculture has been the major factor affecting water volumes and its duration in wetlands. Some wetlands have too much water as nearby paddocks are drained into the wetland, while other wetlands have lost water. Sediment build up can also be an issue.
As wetland managers, landowners can help ensure water levels and quality are appropriate. The use of deep rooted species, either perennial pastures or trees, can help where drainage and land clearing have lead to an increase in water input. Perennial pastures and vegetated spoon drains are also effective in reducing the velocity of surface water flow, reducing erosion and sediment build up and turbidity in the wetland.
The reverse of this problem is reduced water levels from drainage, over extraction and stock watering. This is being exacerbated by climate change. The incorrect placement of plantation trees can also be a problem.
Weeds and pasture
Weeds are a major threat to wetlands as they easily flourish in disturbed, nutrient enriched sites. Weed control can be difficult in wetlands as the use of herbicides must be done carefully. This is because many aquatic organisms can easily be killed or harmed by the chemicals and surfactants in herbicides. To make weed control in wetlands easier it is important to remove any weeds that establish themselves before they become a larger problem. your local catchment officer can help you to identify any weeds in your wetland and provide ways to control and remove them.
Some common wetland weeds in Torbay include Arum lily, Taylorina, Typha (Bullrush) and Blackberry. The Torbay Catchment Group, City of Albany and the Department of Agriculture and Food WA can help you with the best way to tackle these weeds.
Pasture species, such as kikuyu, have the potential to become serious weeds in a wetland. The best way to manage this risk is to provide an adequate buffer between paddocks and natural areas. The size of the buffer will generally depend on the type of pasture and the size and quality of the wetland being protected.
A shelter belt of local trees provides a good buffer, with their shade reducing weed growth while providing protection for stock.
Unrestricted stock access to wetlands will inevitably lead to habitat destruction and a reduction in water quality. Trampling and grazing of vegetation will destroy many existing plants and prevent native seedlings from re-establishing. This will promote weed growth, further reducing the habitat value and water quality, as well as increasing the fire risk. The pugging and compaction caused by stock also leads to soil degradation. Stock defecating in wetlands will add additional nutrients to the system, which leads to algal growth, lower oxygen levels resulting in fish deaths and a decrease in the aquatic habitat and aesthetic value of the wetland.
Fencing of wetlands is considered a vital component of best management practice where stock currently have access. If the wetland is used as a source of stock drinking water, watering points such as a pipe and trough system or limited access points should be installed. These watering points are also better for stock health as they reduce contact with pathogens.
The Torbay Catchment Group can provide financial and technical assistance for fencing, watering points and stock crossings.
Wetlands provide permanent and temporary habitat for a wide range of animals. you may have noticed how different bird species use your wetland throughout the year. Protecting and enhancing this habitat can be helped by reducing weeds, ensuring a good, dense mix of local species (from sedges to trees), controlling pest animals, restricting stock access and protecting the water quality (chemicals and nutrients). Remember that dead trees and logs are a favourite home for many birds and animals so these should be kept wherever possible.
While the threat of fire is not as serious as in bushland areas, fire can still occur in wetlands. In particular, the peaty, coastal swamps of the lower catchment. Fires in these swamps can smoulder for long periods, causing substantial loss of organic material and changes to the swamp’s hydrology. Fires in wetlands also leave the area more susceptible to weeds.
Fires can be avoided in wetlands by reducing the fuel load caused by annual weeds. Again, restricting stock access and undertaking proper weed control are good management techniques to reduce fire risk.
Water quality is an important issue for all aquatic systems. This covers a range of parameters including oxygen concentrations, temperature, nutrients, salinity and sediment or turbidity. Poor water quality can be dangerous for sensitive animals, like frogs and macro-invertebrates. As these animals are often the bottom of the food chain, larger animals are also dependant on good water quality.
In the Torbay Catchment, high levels of nutrients are a major threat to water quality. These nutrients promote excessive algal growth and unfortunately blooms are now common, many even being toxic. These blooms are not only a threat to aquatic life through reduced oxygen levels in the water, but they can also impact upon the recreational and aesthetic qualities of the wetland through their extremely offensive odours.
Protect your wetland’s water quality by removing stock access and minimising nutrient runoff. you can do this by applying the right amount of fertiliser for your situation (undertake regular soil testing), planting buffers between the paddock and wetland and planting native vegetation or grasses along drains to stop erosion and trap excess nutrients.
Plants of Torbay’s wetlands
Wetland vegetation is often found in distinct zones that correspond to water levels, duration of waterlogging/ inundation and soil types. It is important to identify where the various zones lie to aid in management. Wetlands in the Torbay catchment include the following species
- Meeboldina scariosa
- Juncus pallidus
- J. pauciflorus
- J. kraussi
- Baumea juncea
- B. articulata
- B. preissii
- B. vaginalis
- Eleocaris acuta
- Sword Sedge (Lepidosperma effusum)
- Swamp Banksia (Banksia littoralis)
- Watti (Taxandria juniperina)
- Paperparks (Melaleuca preissiana, M. raphiophylla and M. cuticularis)
- Blackbutt (Eucalyptus patens)
- Ti Trees (Taxandria parviceps, T. linearfolia and T. fragrans)
- Wonnich (Callistachys lanceolata)
- Albany Bottlebrush (Callistemon glauca)
- Swamp Bottlebrush (Beaufortia sparsa)
Protecting a valuable asset
Wetlands that are dominated by sedges are known as sedgelands. Sedgeland communities are of particular importance for protection.
At a state level, the total area of sedgelands remaining is 59% of the original extent, with 27% of that remainder occurring within the South Coast region. Only 25% (2074 hectares) of the sedgeland vegetation type originally occurring in Torbay catchment currently remains. As a result of this the Torbay Catchment Restoration Plan aims to have the remaining areas of sedgelands properly managed and their extent and condition improved where possible.
The Department of Water has a series of publications called Water Notes and Water Facts. They cover a range of topics relating to wetlands and rivers. They can be accessed by searching the Department of Water website: www.water.wa.gov.au or contacting the Department of Water office in Albany.
Southern Weeds and their control
by John Moore and Judy Wheeler,
Department of Agriculture Bulletin 4558/02
Western Weeds – a guide to the weeds of Western Australia
by BMJ Hussey et al,
Plant Protection Society of Western Australia
WHO CAN HELP ME?
Torbay Catchment Group has funding available to help you protect and enhance wetlands on your property.
- Contact the Torbay Catchment Group (TCG)
by email email@example.com or ring the Department of Water on 9842 5760
- Department of Environment & Conservation
120 Albany Highway
ALBANY WA 6330
Phone: 9842 4500
- Department of Water
5 Bevan Street
ALBANY WA 6330
Phone: 9842 5760
Fax: 9841 1204
- South Coast Natural Resource Management
444 Albany Highway
ALBANY WA 6330
Phone: 9892 8537
Fax: 9841 2707