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A wetlands threat to be taken seriously
Cabomba carolina and Cabomba spp.

Cabomba (Cabomba caroliniana) is a fully submerged aquatic plant; originally a native of the Americas it was introduced into Australia as an aquarium plant. It was first recognised as naturalised in 1986. Since then it has become established in areas of Queensland, New South Wales and Victoria either because of having been deliberately planted in native freshwaters for commercial purposes, or possibly through discarding by aquarists. Its complete distribution in Queensland is not known.

A primary concern with cabomba in Queensland should lie with its potential as an environmental weed. Cabomba is considered to be an important potential environmental weed of the Wet Tropics Heritage Area (Wet Tropics Management Authority 1995). Its ability to replace native aquatic plants with the likely result that native fish and invertebrate populations are displaced, together with the ability to effectively infest large areas of water suggest that if allowed to establish throughout the state native aquatic life would be considerably endangered.

Bioclimatic modelling suggests that most of the eastern coastal strip of Queensland is excellent habitat for C. caroliniana and, particularly in the north of the state, C. furcata could become established.

Cabomba currently appears to have a limited distribution in Queensland. The spread of cabomba into other areas must be guarded against. Now that an effective chemical control is available for the weed, local eradication and restriction of its distribution are feasible.

Goals for action on cabomba are:
Locate all infestations of cabomba within the state.
Eradicate current small and new infestations. This will only be achievable for small (<1 ha) localised infestations.
Restrict the distribution of cabomba to the few major impoundments in which it is currently found.

News

Under construction

 

Most text on this page but not all is copied verbatim from Department of Natural Resources and Mines, keep up the good work. "Cabomba, Pest status review series, Sept 1996

 

 

 

Preliminary findings indicate that cabomba infestations increase the colour of potable water, hence increasing the cost of treatment; perhaps by up to $50/ML. Cabomba is also an aggressive invader of native freshwater systems, particularly if they are slightly eutrophic. It out-competes native freshwater plants and is of doubtful value to native fish or aquatic invertebrates. Potentially, it could be a very damaging environmental weed. Additionally, dense infestations impede aquatic recreational activities and the risk of drowning from entanglement is a real danger to people using the water body.

The ecology and life cycle of cabomba in Australia is not well known. In the north of Queensland, it grows and flowers throughout the year, but in southeast Queensland it may stop growing and flowering in the winter months (July and August). It can rapidly infest water bodies through vegetative growth of stem fragments as small as 1 cm. Cabomba in Queensland may be sterile as sexual reproduction has not been proven to occur here.

Effective control may be difficult to achieve. The n-butyl ester of 2,4-D mixed with diatomaceous earth has proven effective in still waters but may not be an acceptable control method in some situations. Drawdown of impoundments can be effective in controlling cabomba but again may not be a viable alternative. Biological control using grass carp could be possible but is not to be supported.

Stopping the illegal trade in cabomba, heightening public awareness of the weed potential of the species and early detection and control of new infestations are the keys to restricting further spread of the weed in Queensland. Declaration of the genus Cabomba statewide would give support to these activities.

Environmental Benefits

Where naturalised, cabomba provides the usual benefits that aquatic plants generally have in aquatic systems: it oxygenates the water, protects against bank and bed erosion and removes nutrients from the water. Whilst it does provide fish habitat (at least in the USA) it has no wildlife value (Martin and Wain 1991, Harman 1994).

 

Management and Control Practices

Legislative Status in Qld

Cabomba, Cabomba caroliniana, is a declared plant under the provisions of the Rural Lands Protection Act. Currently it is declared as category P2 in the local government areas of Atherton, Eacham, Johnstone and Mulgrave and where found the plant must be destroyed and it is illegal to sell or keep the plant throughout the state.

The separation of the different species of cabomba is difficult for even experienced botanists and in the past, there has been confusion over the

definition of the species that has led to concerns over which form of cabomba is the declared form. Because of this and the potential for other species of cabomba to establish in Queensland a revised declaration that covered the genus as a whole would make a preferable legislative instrument. Declaration for the whole state would raise awareness of cabomba as a potential significant threat to Queensland’s freshwaters.

Containment and Eradication Strategies in Queensland

Cabomba currently appears to have a limited distribution in Queensland. The spread of cabomba into other areas must be guarded against. Now that an effective chemical control is available for the weed, local eradication and restriction of its distribution are feasible.

Goals for action on cabomba are:

 Locate all infestations of cabomba within the state.
Eradicate current small and new infestations. This will only be achievable for small (<1 ha) localised infestations.
Restrict the distribution of cabomba to the few major impoundments in which it is currently found.

 

The spread of cabomba can be restricted by:

 Early detection. Weed control officers and people in the water industry should be made aware of the weed and how to identify it.
Increasing public awareness of the weed and its potential to disrupt aquatic recreational activities.
Educating people on the need to clean boats and equipment after recreational or commercial use of an infested water body.
Eradicating wild harvesting of cabomba and controlling illegal commerce in cabomba.
The preparation and implementation of containment plans for cabomba in situations where infestations are located in catchment headwaters.

It is essential that where cabomba is known to occur in a publicly accessed water body information signs are positioned adjacent to access points such as boat ramps which clearly indicate the necessity of cleaning down boats and equipment to stop the spread of the weed to unaffected areas.

8.3 Management Strategies for Aquatic Systems.

There are two major problems constraining action in relation to cabomba:

 New infestations are difficult to detect since inspections for this type of weed are not regularly made and the weed is a fully submerged aquatic plant and is not easy to see until the affected area is quite large.
The weed grows very quickly and it is highly invasive. Unless early control is initiated the weed quickly establishes throughout the system and eradication is a hopeless task.

The first constraint could be met through the development of an adequate and easily used detection system for submerged weeds. The SAVEWS system for the hydroacousitic detection and mapping of submerged water plants being developed by the Tennessee Valley Authority and the U.S. Army Corps f Engineers (Sabol and Melton 1995) is worthy of consideration for the easy detection of cabomba infestations in Queensland impoundments. Integrating the regular use of such a monitoring system into the routine management of reservoirs and impoundments would go a long way to meeting the second constraint through enabling early control efforts.

Control practices need to be integrated into the general management of the impoundment, canal or river. Since cabomba is likely to be able to establish in farm dams, landholders also need to be aware of its potential and integrate checks for the weed into their general property management plan.

The control practices used must be tailored to the particular type of water body being treated. In a potable water supply, very regular mechanical harvesting may be the only viable method. If an impoundment can be taken off-line then a suitably timed drawdown and a chemical treatment of the root mass may be an available option. If drawdown is not an available option, the infestation may be thinned by an initial chemical treatment and the remaining plants removed by hand. If impoundments flow, or could overflow, into catchment headwaters, containment plans must be put into place which will stop cabomba washing into the river system.

 

To adopted full Cabomba management plan

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