AFRICANEWS

Malawi

Hyacinth chocking Lake Malawi

Environment

Water hyacinth is chocking Lake Malawi, which is not only home to a large number of fish species, but a popular holiday destination. But the authorities are fighting back.

The future of Malawi's largest lake, Lake Malawi is in doubt after the troublesome aquatic weed, water hyacinth invaded it. Not only is weed threatening life in the lake, but also the Shire River, a tributary of the Zambezi. The hyacinth forms a thick, green carpet on the surface water, rendering the river and the lake impassable for boats.

The hyacinth carpet covers a huge area of the lake surface, preventing sunlight from penetrating the water. This inhibits the plankton growth, which is an important link in the food chain. Consequently, more than 500 species of fish in the lake in threatened with extinction. In 1984, the Britain based World Centre for Environmental Monitoring declared the Lake Malawi National Park a world heritage site while the United Nations Educational, Scientific and Cultural Organisation (UNESCO) cites the lake as an important link in the study of evolution of certain fish species. The weed growth also impacts negatively on hydroelectric and irrigation projects. When it proliferates, hyacinth absorbs huge amounts of nitrogen and oxygen, environmental expert Roger Day explains. "The resulting lower oxygen content of the water could have very adverse effects on the biodiversity and aquatic ecosystem."

Harry Thompson, Malawi's Natural Resources and Environmental Affairs minister, is seriously concerned about the lake's welfare. He says the fish population in the lake is declining and in addition the hyacinth impacts negatively on tourism. "People from all over Malawi and the world come to our lake to swim and dive, but numbers are declining. If the hyacinth is allowed to take over, few tourists will find the lake attractive," says Thomson.

The good news, however, is that active attempts at curbing the spread of the plant have began showing results. In 1996, the Malawian government initiated a programme to exterminate the hyacinth. Project leader Patrick Maseko says good progress has been made. "We are doing everything in our power. Initially we sprayed the water hyacinth with chemical herbicides, but later abandoned this method as it is inefficient and expensive," says Maseko. It was then decided to physically attack the hyacinth. Local communities on the lakeshore and banks of Shire River helped pull the hyacinth from the water and burn it. There are also special boats, which waddle through highly hyacinth infested areas and remove it in the process.

"We informed the local population of the dangers the hyacinth posed and encouraged them to cooperate with the government in the battle against the plants," Maseko explained. "The different villages formed shore committees who not only exterminate hyacinth but also prevent fishermen from over-fishing the lake. Biological pest control methods employed elsewhere were also tried. Malawi government imported in 1997 hyacinth beetles from South Africa and bred them in Malawi. About 500 000 of the insects have been released in the contaminated areas to devour the hyacinth. "This type of biological warfare has proved most effective in exterminating the plant. The beetles eat the leaves while the larvae destroy the plant stems," points out Maseko.

Although the hyacinth has been declared a pest plant, it does have some use. In Sudan it is used for manufacturing biomass energy, for household purposes such as lighting, cooking and cooling while in Kenya it is used to make baskets and chairs.

| CONTENTS | AFRICANEWS HOMEPAGE |

AFRICANEWS - Koinonia Media Centre, P.O. Box 21255, Nairobi, Kenya
tel: +254.2.576175 (voice) Fax:- +254.2.577892 (fax-modem)
AFRICANEWS on line is by Koinonia Media Centre