Invasion Biology

Wednesday, January 24, 2007


Water hyacinth is the plant which floats freely in the water. The plant is indigenous in
the continent of South America. Globalisation, International trade and transportation lead to the spread of water hyacinth in the continents of Africa, North America, Asia and Australia. In South Africa, Water hyacinth first came into existence in the province of KwaZulu-Natal in 1910 (Coetze, 2007) from South America. The species can rise to the height of approximately 1m in height above the water.

The species is now spreading in the Eastern part of South Africa. The plants serve as habitats for small invertebrates animals such as Fish and Frogs. The modes of dispersal include movement of People and Ships all across the boundaries. People move from one place to another either as part of tourism, trade, and other sport activities such as soccer, rugby and tennis. When People move from one place to another they use different types of transport such as trains, buses and planes. The types of the transport that they use carry the alien invasive species from one place to another. The species has been found to be a problem in Kenya where it suppresses other aquatic plants (Coetze, 2007). The plants float on the water and prevent sunlight from reaching other aquatic plants.

The prevention of the sunlight from reaching other aquatic organisms mean that other organisms will die because of the absence of the oxygen and the process of photosynthesis is reduced greatly. Lack of sunlight mean that the process of photosynthesis in water is no longer going to take place. If the process of photosynthesis is no longer going to take place, this means that plants which live in water such as algae (autotrophic) will no longer manufacture their own food. Small animals will die because there will be no longer food which is available for them. In countries such as Australia and Papua New Guinea, the plant destroys native plants. The killing of the native plants by water hyacinth is encouraged by the fact that, there are no preventive measures in place in the above mentioned two countries (Wikipedia contributors, 2007).

The dying of other aquatic organisms means that the aquatic ecosystem is disturbed because of the reduction in the quality of water. The reduction of the quality of water will also affect the livestock and People living around the affected areas. This is because in some parts of the globe, People are still dependent in water from the rivers. If the livestock are infected with diseases, this may also affect People feeding in the meat of those animals. The other problem in which water hyacinth possesses is that the species acts as a vector in which Mosquitoes build their nests. This means that Mosquitoes will be able to carry their diseases (Malaria) to the People who are living near to the area where the plants are available (Wikipedia contributors, 2007).

Water hyacinth forms fibrous roots which are thick, branched and dark in colour under the water. On top of the water, the species forms a thick mat which prevents many water activities such as swimming, fishing and canoeing. When the species dies, decomposers such as bacteria and fungi are responsible for the decaying of the dead organic matter. The dead organic matter provides other aquatic organisms in the water with food.


Coetzee, J. 2000. Animals, Plants and the Environment [Online]. [cited 2007 January 18]. Available from:

Wikipedia contributors. Water hyacinth [Online]. Wikipedia, The Free Encyclopedia; 3 January 2007, 09:23 UTC (cited 2007 January 23]. Available from:

Peter Muvhali
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Fax: 012 8423676


  • Some thoughts...

    Fish and frogs are NOT invertebrates!

    Please watch your formatting (e.g. the first paragraph) and your grammar.

    What is the scientific name of the water hyacinth?

    Your concluding paragraph is a bit weak - it would've been better to have placed it somewhere earlier on.

    Try not to rely so heavily on Wikipedia.

    By Blogger NcK, at January 24, 2007 4:54 PM  

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