Aquatic Weeds
Get off our backs! Threatened species week 2007
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© EPA, image by George Aldridge
To raise awareness about how people can help our aquatic wildlife, this year’s theme for Threatened Species Week is ‘Get off our backs!’ Queensland’s aquatic and coastal species are baring the brunt of our ever expanding use of oceans and waterbodies. Although many people do care about wildlife, it seems that the message isn’t reaching everyone. The careless use of our oceans, beaches and waterways has a direct impact on many threatened species. However, slight changes in human behaviour can make a real difference to threatened species.
WEEDS!
Many of Queensland’s freshwater lakes, billabongs, creeks and rivers are threatened by the introduction of non-native aquatic plants. Many of the introduced species flourish and they can shade out native plants and reduce the quality of habitat for native animals.
Since European settlement aquatic plants have been introduced for many purposes. Some species have been purposefully introduced as ponded pasture species (plants introduced to areas of artificially impounded water), to be additional fodder for grazing or harvesting, while others have been accidentally introduced (occasionally on purpose) as aquarium plants, ornamental pond and lagoon species.
Aquarium or garden pond escapees
The introduction of aquarium and pond weeds is a significant problem for our native freshwater plants and animals. Aquatic weeds continue to spread through flooding moving the plants to other waterways, introduction through emptying of aquariums and ponds and intentional introduction. Many aquatic weeds have been introduced or colonised new waterways because of release from aquariums or backyard ponds. These weeds include salvinia (Salvinia sp.), cabomba (Cabomba caroliniana), caulerpa (Caulerpa taxifoliaEgeria densa), dense waterweed (Egeria densa), yellow waterlily (Nymphaea mexicana) and glush weed (Hygrophila costata).
What is threatened by these escapees?
All the animals and plants living within a waterway or waterbody may be affected by the presence of a weed outbreak. Many of these weeds survive well in their new environments and grow at a fast rate. This may exclude native plants and can also have an impact on native animals. In north Queensland, platypus and water rat numbers are lower in creeks infested by cabomba1.
Other freshwater species that can be detrimentally affected by aquatic weeds include Australian lungfish and freshwater turtles. Aquatic weeds such as water hyacinth and salvinia can have major effects on lungfish habitat by reducing dissolved oxygen levels, reducing water temperature and affecting breeding habitat by preventing light penetration and physically smothering native plants. Freshwater turtles such as white-throated snapping turtle (Elseya albagula), Fitzroy River turtle (Rheodytes leukops) and Mary River turtle (Elsuor macrurus), are threatened by aquatic weeds as it restricts their access to river banks where they nest.
Aquatic weeds can also affect the recreational and aesthetic values of the water body if it is infested. Heavy infestations can make boating and swimming difficult and can also be dangerous for children and animals if the weeds look like solid ground.
Salvinia in early stages © Lisa Ford EPA
What can you do?
Where can you find more information?
Weed Busters – Waterweed fact sheet
Weed management guide - Cabomba
Weed Management guide – Salvinia
NRW Pest series – Salvinia species
NRW Pest series – Dense waterweed
NRW Pest series - Lagarosiphon
1. CRC Weed management. 2003. Weeds of National Significance – Weed Management Guide – Cabomba (Cabomba caroliniana). Viewed 1 August 2007 at http://www.environment.gov.au/biodiversity/invasive/publications/pubs/c-caroliniana.pdf
‘Get off our backs’ logo © EPA, image by George Aldridge.
Last updated: 31 August 2007
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