Aquatic weeds

Aquatic weeds are among the most damaging weeds in the world. They can grow rapidly, spread through rivers, wetlands and floodplains, block waterways, reduce water quality, impact fishing and recreation and displace native plants and animals.

Many aquatic weeds found overseas and interstate originated from the aquarium, ornamental pond and water garden trade. Once established in natural waterways, aquatic weeds are extremely difficult and costly to control. In some cases eradication is not possible.

The Northern Territory remains free of many of Australia's worst aquatic weeds. Community awareness and early reporting are critical to protecting our waterways.

If you see a suspected aquatic weed, report it immediately to the Weed Management Branch.

Aquatic weed species of concern

The following species are prohibited or serious aquatic weeds that pose a threat to the Northern Territory.

• Alligator weed
• Amazon frogbit
• Ambulia
• Cabomba
• Limnocharis
• Sagittaria
• Water hyacinth
• Water mimosa

Why aquatic weeds are a threat

Aquatic weeds can have significant environmental, economic and social impacts. They often form dense mats that block waterways, reduce oxygen levels and harm fish populations, outcompete native aquatic plants and alter wetland ecosystems and wildlife habitat.

They can also interfere with fishing, boating and other recreational activities, increase mosquito breeding habitat and create substantial ongoing management costs.

Many aquatic weeds can spread from very small fragments, making their accidental movement between waterways easy and increasing the risk of rapid infestation.

Help protect NT waterways

Here is how you can help prevent the spread of aquatic weeds in Territory waters.

Aquarium and pond owners

Never:

• release aquarium plants into waterways
• release aquarium fish, turtles or other aquatic pets into waterways
• dump pond plants into creeks, drains, rivers or wetlands
• flush unwanted plants down drains.

Instead:

• dispose of unwanted plants responsibly
• share plants only if you are certain they are not declared weeds
• check plant names before purchasing aquatic plants
• report suspicious species.

Fishers, boaters and recreational water users

Before leaving a waterbody:

• inspect boats, trailers and equipment
• remove any attached plant material
• clean nets and fishing gear
• drain water from boats and equipment where appropriate
• report unusual aquatic plants.

Report aquatic weeds

Early detection provides the best chance of successful eradication.

Report any suspected aquatic weed by:

• emailing clear photographs and location details to weedinfo@nt.gov.au
• calling the Weed Management Branch on 08 8999 4567.

When reporting an aquatic weed infestation, include:

• clear photographs of the plant
• location coordinates if available
• details of the affected waterbody
• an estimate of the size of the infestation.

Providing this information will assist with accurate identification, assessment of the extent of the infestation and the timely implementation of appropriate management actions.