Lake Victoria in Africa has been overrun with an invasive plant called the water hyacinth. The plant has affected the local drinking water, which has caused more sicknesses that were not previously prevalent. Water hyacinth has also affected fishing, a major income and food source. Insects called weevils have been introduced as a biocontrol method to eliminate the water hyacinth. Biologist Adrien Williams believes that although weevils did play an important role in the reduction of water hyacinth the largest destruction of water hyacinth was due to the 1997/1998 El Nino. Biologist John Wilson states that the use of weevils in destruction of water hyacinth is the main reason why the plants masses were decreasing. However, the El Nino might have propelled that process.
I agree with Wilson in that the weevils played an important part in the removal of water hyacinth from Lake Victoria and without them the plant would still be a problem. The El Nino alone would not be able to destroy the plants in the massive amount in such little time. The El Nino acted as a positive unexpected factor in the hyacinth’s removal. The change in weather also had a negative affect. Because weevils only feed and affect the water hyacinth, once its numbers lowered due to the destruction of their habitat and food there would be less weevils. Now that we know that the water hyacinth has restored itself we can say that the population decrease of the weevils after the El Nino played a huge role in its resurgence so we cannot rely on nature to come to our rescue. An El Nino only occurs every two to seven years so there needs to be something in place to control the water hyacinth.
This being said biocontrol is not a quick fix all. Recently, due to heavy rains and floods that “swept agricultural run-off and nutrient rich sediment” into the lake, there has been a rebound of water hyacinth. There aren’t going to be drastic changes within a few years but with time the weevils will help deplete the hyacinth to a manageable amount.
NASA Earth Observatory. 2007. Water Hyacinth Re-invades Lake Victoria. http://earthobservatory.nasa.gov/IOTD/view.php?id=7426. Viewed 20 Jan 2010.
Williams, A. E., R. E. Hecky, and H. C. Duthie. 2007. Water hyacinth decline across Lake Victoria – Was it caused by climatic perturbation or biological control? A reply. Aquatic Botany 87:94-96.
Wilson, J. R. U., O. Ajuonu, T. D. Center, M. P. Hill, M. H. Julien, F. F. Katagira, P. Neuenschwander, S. W. Njoka, J. Ogwang, R. H. Reeder, and T. Van. 2007. The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp. Aquatic Botany 87:90-93.
The water hyacinth debate is really an interesting one. The debate is just as interesting, but i wonder how early is too early to state your opinion? I thought it was all very well written, but i question whether you should explain the authors opinions more before stating which you do or do not agree with. Also, there seemed to be little recognition of the NASA Observatory article.
For my revisions I reread the articles to determine whether I found any new insights to my opinion. After reading the articles again I thought the articles were saying the same thing. As suggested by my classmate I looked at the other article and made revisions. These revisions from this article included more recent information on the status of the water hyacinth invasion.