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And the invasive water weed ravages water bodies

By Vision Reporter

Added 22nd May 2012 12:37 PM

Today, JOSEPH SSEMUTOOKE writes about the water hyacinth that threatened to destroy Uganda’s water bodies.

And the invasive water weed ravages water bodies

Today, JOSEPH SSEMUTOOKE writes about the water hyacinth that threatened to destroy Uganda’s water bodies.

To mark 50 years of Uganda’s independence, New Vision will, until October 9, 2012, be publishing highlights of events and profiling personalities who have shaped the history of this country. Today, JOSEPH SSEMUTOOKE writes about the water hyacinth that threatened to destroy Uganda’s water bodies.

At one time in the 1990s, there were genuine fears that the surface of Lake Victoria was destined to be lost to an invasive waterweed that was fast forming floating rafts all over the water body.

The second largest lake in the world had been attacked by the water hyacinth. The water hyacinth is one of the world’s most invasive water weeds. The hyacinth was eating up several other sizeable water bodies in the East African region, including other lakes and several rivers in Uganda. Lake Kyoga was the other lake that was attacked by the hyacinth.

It would take substantial efforts from allied stakeholders to overcome the problem. And still, by the time the problem was solved, there had been some disruptions suffered across various sections of the communities around the affected water bodies. Substantial amounts of money had been spent, and the bio-diversity of the region had been affected.

Emergence of the problem
Its origin is believed to be South America. The water hyacinth was not reported in Lake Victoria until 1989, although some researchers say the weed had been growing in Africa’s waters since the 1870s.

There were rumours among the locals that the weed had been brought by ill- willed people who wanted to destroy the lakes in Uganda. By 1993, the Natural Resources Institute of London had declared that about 30% of the lake was covered by the plant. By 1995 it had declared the weed to cover nearly 70% of the lake’s surface. By 1997 the weed had reportedly spread to Lake Kyoga.

Effects on environment/economy
Lake Victoria is a source of food and transportation so as the hyacinth spread access the lake, the livelihoods of a many communities around the lakes would be at risk. The weed caused difficulties in water extraction, blocked irrigation canals and made travel across the lake difficult. The weed also led to disputes between local communities (as they fought over less-weed covered waters) and led to an increase in water borne diseases. 

Several communities in the affected areas also reported a decrease in biodiversity which scientists explained to arise from the death of several water organisms, thus creating gaps in the ecosystem. The hydro-electric plant at Jinja was also threatened with closure, owing to weed build up, which slowed down the turbines.

Dealing with the hyacinth
By the mid-1990s the country was desperate for ways to solve the hyacinth problem. According to the United Nations Environment Programme, the Lake Victoria Environmental Management Project was one of the stakeholders that first contributed seriously to the fight against the water hyacinth. The project, jointly funded by the World Bank and the governments of Tanzania and Uganda, initiated a five-year programme at the cost of US$ 70m, which went a long way in research and sensitisation, among other efforts.

Dr. Aryamanya Mugisha, the former deputy executive director of the National Environmental Management Authority (NEMA), recalls that in 1997, the Government formed a body to tackle the problem. The body was called Lake Victoria Water Hyacinth Eradication Programme.

The programme came up with solutions from different organisations. But then there arose the problem of which method to use without affecting the environment.

These were; mechanical (using machines to weed out the hyacinth), biological (using pests that feed on weeds) and chemical (using drugs and pesticides).

The use of chemical control was supported by some people but according to Aryamanya, NEMA opposed this option. The mechanical option, which was implemented first was both very costly and ineffective. The machinery and manpower to remove the weeds were expensive yet the hyacinth grew back so quickly.

The biological method was tried around 1998 and it proved successful. The method had been used successfully in Kenya by Kenya Agricultural Research Institute.

An entomologist specialising in biological control at the National Agriculture Research Organisation (NARO), Dr James Ogwang, worked out a fast way to solve the problem.

A breeding programme of two water hyacinth-eating weevils (the mottled water hyacinth weevil and another weevil) was established in Uganda.

It released more then 250,000 weevils at 30 sites along the Lake Victoria shoreline. At the height of the problem, 12 bio-control rearing centres had been established at different landing sites on Lake Victoria.

Doctor Ogwang
Entomologist Dr. James Ogwang, for his efforts to fight the weed, attained global recognition. He presented his work at the annual meeting of the American Society of Plant Biologists in the US in July 2007. It was thereafter declared as a method for eradicating the hyacinth from Africa’s water bodies. Ogwang’s work on the Lake Victoria Water Hyacinth Eradication Programme was even featured on National Geographic’s television series, Strange Days on Planet Earth. It still shows occasionally.

After 2000
By 2000, Uganda’s water bodies were cleared of the hyacinth except for some areas where it would re-emerge but would be cleared without much difficulty. For instance, in 2006, the weed started growing on Lake Albert it was cleared off. Thereafter, Uganda became one of the countries of reference (featured in several UN publications) regarding successful management of the water hyacinth problem.

And the invasive water weed ravages water bodies

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