Invasion Biology

Wednesday, January 24, 2007

Salvinia molesta

Salvinia molesta is a scientific name for Kariba weed. Salvinia molesta was originally from Brazil and it is well known as a free-floating water fern. This species was found in the Zambezi River in Africa in about 59 years ago. Salvinia molesta has also invaded other countries around the world.

Department of the environment in Australia describes Salvinia molesta as a free-floating rapid-growing, mat-forming, annual fern; individual plants up to 30 cm long with numerous leaves. At the early stage the species leaves lie flat on the surface of the water and at the late stage the leaves bend at the edges, this features distinguishe S. molesta from S.minima. Salvinia molesta can grow rapidly (double within one week) to cover the entire water surface with a thick mat of vegetation. Salvinia molesta causes a great impact in aquatic environment and local economics. It affects the aquatic environment by preventing atmospheric oxygen from entering the water by doing this, it makes the water unfavourable for aquatic animals and it also reduces biodiversity of wetlands. It also dangerous to people since it “provide an ideal breeding environment for disease-carrying mosquitoes” [1]. In Senegal River, Salvinia molesta cause a threat to the biodervisity of the ecosystem conserved by Djoudj National Park.

Salvinia molesta spread quickly in a favourable condition and in size can double almost every two days. It spreads it selves during flooding and by human activities into new catchments. This species can leave under frozen temperature and on the water temperature up to 43°C. It can also survive under a dry condition.

The Australian Government, Department of the Environment and heritage suggested the better method for preventing the spread of Salvinia molesta since is a threat to the biodiversity, the public must be educated not to spread invasive species deliberately and “monitoring should be undertaken in catchments at risk from salvinia invasion” after floods [2].


1.Unknown. Salvinia molesta, Weeds of National Significance: Weed management guide. Department of the Environment and Heritage and the CRC for Austrialian Weed Management, 2003. [Internet] Available from:
2. Cronk Q.C and Fuller J.L (1995). Plant invaders. Champman and Hall. [Internet]. Available from

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  • Hey there!

    You mention that Kariba weed is found in Africa, but then spend the rest of your post talking about what the Australians have to say about it. How big a problem is it in Africa? And what's being done about it?

    Also, you don't have to make every cited reference a direct quote, you know...

    By Blogger NcK, at January 24, 2007 5:26 PM  

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