Hyacinth

HYACINTH

The water hyacinth (Eichhornia crassipes), has become a major problem in South African water systems over the years. A lot of different versions can by heard of how this plant was actually introduced to our country, with the most popular being of a woman that brought it in from Japan as a decorative plant for her Koi pond. When she found the plant was beginning to over run her pond she would thin them out by throwing the majority into the Vaal river system. I can not confirm nor deny this but can quote the following. "The water hyacinth (Eichhornia crassipes) was first reported at the beginning of the twentieth century in the Nile delta in Egypt and in the province of Natal, South Africa. It is an invasive aquatic plant that originated in Brazil, where it develops moderately in its natural habitat. Introduced to Africa as an ornamental plant, in less than a century it spread to more than 50 countries around the world. An obstruction to navigation, this species can block agricultural irrigation canals and turbines in hydroelectric dams. Its thick vegetal carpet, which can double in area in twelve days, causes eutrophication, this reduces the oxygen content of deep waters and leads to the asphyxiation of underwater life."

PLANT GROWTH

Now that we have established how this water weed was introduced in SA the next question is why does it flourish so in our water systems. This biomass of water plant can double up in biomass size in around two weeks and it flourish in nutrient rich water. Nutrient removal takes place during the treatment of Waste water and over the last few years, these processes has deteriorated to such an extent that less than 10% of Waste Water treatment plants are actually complying to the Water Act. This is due to loss of experience and knowledge and also greatly to under funding and corruption. Some of these treatment works are very badly neglected and it will cost millions to get them back to a 100% working condition. Further more expansions to sewage systems has increased tremendously over the last few years and this has put great strain on these treatment processes. A lot of them is already functioning at more that 120% the actual design capacity and this also cause them to be unable to comply to DWAF standards of effluent. The effluents from these treatment works are introduced back to our water systems and is rich in, but not limited to, Phosphates and Nutrients. This is a great source of "food" for Hyacinth and can be contributed to one of the reasons to why this water weed flourishes in our water systems.

Spreading of the weed

The weed mainly spreads through water currents in this manner will continue to spread in our water systems. This however is not the only means of distribution. I grew up in Benoni and none of the dams ever showed any signs of this weed. Now one can see this weed in the dam by Lakeside mall and by the golf course. The obvious reason to how it got there is by means of powerboats. The dam by the golf course has for the past 10 or so years had a company run a Ski school there and this seems to be how the weed was introduced to these dams.

If we look at all the dams in SA where hyacinth are present, most of them do allow power/motor boats. Out of all these dams maybe one or two has introduced systems where the boats hull and trailer will be treated before entering and/or leaving the premises. At first glance this might seem insignificant, but the saying "Prevention is better than cure" comes to mind.

Utilizing and Solving the problem

Before any solution can be established to curb the spreading and reproduction of this plant, governing bodies must stop looking for excuses and stop blaming each other. I am surprised that they have not blamed local animals like the Ibus for spreading this plant. This seems to be the way out for them as they have done at Hartebeespoort dam, blaming Carp for the state of the dam and not looking at sewage pump stations, where raw sewage overflowed for weeks un-end into the dam. That was just the tip of the Iceberg as there are other waste water treatment systems higher up in the system and these also contributed greatly to the state of the dam.<br><br> <b>Lets look at the following : -

• Where power boats are allowed a system must be implemented where the vehicle, boat and trailer gets treated with a weed control product that will kill any trace of the plant. All vehicles and boats entering and leaving the premises should be treated.
• No individual or enterprise in SA should be allowed to have these plants as decorative in their private water features, ponds and/or dams
• Create work. Start employing individuals, not companies, for removing these plants by hand on smaller dams like Roodeplaat and Hartebeespoort dam. Any/all plants removed should be destroyed on the premises. Do not allow these plants to leave the premises.
• All resorts / private venues should be forced to remove these weeds. Most of them are after-all contributors to the spreading of the weed.
• In Malawi the water hyacinth has been utilized to sterilize the substrate required to grow the edible fungi Oyster mushroom, why has no such program been started in South-Africa ? Surely it will also become a great economic growth factor and will create hundreds if not thousands of jobs.
• Biological control by means of Weed Weevils - (Neochetina eichhorniae)

These are just four small ideas to help curb the growth and distribution of the weed, thought of by one individual on a Sunday afternoon. Surely our government can come up with more options and solutions.

I know Hengelaarsvriend on Roodeplaat dam had a similar machine in operation with the previous owners a year or two back. I have however not seen this machine in operation for a while.

Surely our government could look at implementing such a machine on one of our local water bodies to see if this would help in getting rid of this water weed, and if so implement the operation of more such mechanisms on our other water systems.

Why wait till it becomes such a problem where it will start having a negative impact on our power plants and water purification works. Once again the saying of "Prevention is better than cure" jumps to mind. Why must a crisis and/or disaster always occur before some action is taken ?

A harvester the state of Florida has implemented for removing this invasive plant

BIOLOGICAL CONTROL

In the late 1990's lake Victoria faced a major dilemma as hyacinth was having a major negative impact on the fishing communities and even on the ports as ships could no longer dock due to the large mats of hyacinth. Fishing villages had been abandoned and millions of people were facing dislocation and hunger because the world's second largest fresh water lake had become so choked by water hyacinth. While government was fighting amongst each other for profit grabbing between mechanical and chemical control of the weed a handful of scientist had the opportunity to establish a healthy community of weed weevils with the help of the local fishermen and villages.

The weevils kill the plant by feeding on the leaves. When the population is high this alone can destroy the leaves. But more importantly, larvae tunnel in the petioles (leaf stalks) and into the crown of the plant, destroying the growing points. When severe, the damage allows water to enter the plant and secondary rotting occurs. The combined damage reduces the plant's ability to flower, set seed, send out off-shoots and replace damaged leaves. Under heavy attack the plants rot and become water logged and eventually sink.

Making use of the weevils is a long term solution and not a quick fix. I am sure we would all love to see our dams clean of hyacinth over night but this seems to be no solution for the long term as hyacinth can survive extreme conditions and can even survive in mud.

 

 

Pictures taken before and after of Lake Victoria with the introduction of the insect

More about Neochetina eichhorniae

Neochetina is a genus of weevils known as water hyacinth weevil which are native to South America.

Neochetina feed almost exclusively on the highly vigorous water hyacinth. There are at least two species: N. eichhorniae or mottled water hyacinth weevil which gets its name from the plant it feeds on (Eichhorniae spp.) and N. bruchi or chevroned water hyacinth weevil which is characterized by a chevron-shaped marking on its back.

Both weevils have been introduced extensively in countries around the world to help control water hyacinth growth which threatens to choke numerous waterways and lakes worldwide. Both these species must be introduced for a controlled impact on water hyacinth.

SUMMARY

Hyacinth is already a major problem in South African water systems. There are long term solutions available, and these should be considered if we want to prevent the possibility of a major environmental crisis. Removing these weeds is not only the responsibility of governing bodies, but lies with each and every individual visiting infested waters.

Yes it will be costly to implement any sort of project, but it will cost much more once we have reached a crisis level. Although the current crisis is not yet effecting our water supplies to power plants and purification works, if left unchecked it will create a major water supply problem in the not to distant future that well cost millions and millions of South African Rands to solve.

It is time that companies and individuals are held responsible for their actions and incompetence and DWAF should start enforcing the LAW and clamp down on Municipalities and organizations responsible for purifying waste water that does not comply with the effluent standards set out by law.

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