Key finding

Invasive non-native flora species — aquatic weeds — can:

• form thick weed mats on water surfaces, preventing light penetration to submerged aquatic plants causing their death
• block creeks, restricting water flow and reducing fish activity due to submerged weed masses. These submerged weeds can choke out fish and other aquatic wildlife
• reduce water quality by preventing light penetration, trapping silt and reducing oxygenation of water, making waterbodies unsuitable for some native fish species
• invade and degrade natural wetlands by outcompeting and smothering native vegetation
• lead to increased flooding — for example, Hymenachne can do this by reducing the flow capacity of drainage networks.

A number of aquatic weeds are established in Queensland. These pest plants are distributed predominantly along the east coast. Established pest plants in freshwater wetlands include:

• alligator weed
• Senegal tea plant
• Hygrophila
• pond apple
• cabomba
• water hyacinth
• Hymenachne
• water lettuce
• Salvinia.

Pond apple can remain viable and germinate in estuarine environments: there is potential for this weed to spread downstream of current infestation sites.

More information:

• Weeds
• Pest distribution maps

• Distribution of Hymenachne (Hymenachne amplexicaulis), 2011–2012. Source: Australian Pest Species Distribution Survey
• Distribution of pond apple (Annona glabra), 2011–2012. Source: Australian Pest Species Distribution Survey

• Previous Invasive non-native freshwater fauna species