Water Hyacinth Removal from a Lake

Water hyacinth,  Eichhornia crassipes , an exotic free-floating invasive plant that is native to South America is threatening Lake Tana in Ethiopia.

The weed is restricting water flow, blocking sunlight from reaching native water plants, and depleting the oxygen in the water - often choking aquatic animals like fish and also interfering with navigation, irrigation, power generation and fishery.

The weed is now estimated to cover 50,000 hectares of the lake forming thick mats that cover the open water. To make matters worse, inflowing rivers also carry heavy loads of soil and suspended sediment into the lake, which affects the water quality and creating favourable conditions for the spread of the weed.

People who tend aquariums and gardens are believed to have spread the plant inadvertently across the Atlantic to Africa and Asia.

This is, therefore, to kindly request the global scientific community at large for technical advice and more to combating the weed to save this life-giving lake which is known to hold 50% of the country’s freshwater and is also the source of the Blue Nile, as it contributes up to 60% of the Nile’s water, and a water source and a source of food in the form of fish for over 123 million people in the Nile Basin.  

For your information, the lake has been listed in the top 250 lake regions of Global importance for biodiversity. It has 28 species of fish, of which 21 are endemic; including most important fishes such as the large African barbs, Nile tilapia and African catfish with the annual commercial fish production value of about USD$ 1.1million.

The potential fish production of the lake is estimated to be 13,000 tons yearly. While it’s current fish production is less than 1000 tons a year only. And recent studies show a serious decline in fish stocks due to the spread of the aforementioned aquatic weed water hyacinth around fish spawning grounds. 

https://youtu.be/ZwXoz7iE6IU    

How can we effectively remove the Water Hyacinth from a lake?

Taxonomy

• Aquatic Ecology
• Ecohydrology
• Environment
• Pollution
• Eutrophication
• Lake Management
• Environment Evaluation
• Aquatic Environment

18 Answers

1. Hi everyone,

   
   This might be an interesting update on what to do with the water hyacinth and a good way of turning a problem into a solution - a startup called HiGi Energy is making clean energy out of the water hyacinth.
   
   "HiGi’s solution is to convert water hyacinth into solid biofuel briquettes that can be used for household and commercial cooking, industrial heating, and potentially power generation. The production of briquettes is sustainable and easy to make, as there is abundant supply of the fast-growing plant"
   
   Check it out here.

2. mr.Teshome Soressa .

   One day collect all the people possible to help and remove all the plants manually or mechanically and immediately dry them somewhere away from the water body.The dried plant fibers can be used to make several utilities.This may be an exercise for the entire day and may be needed to be done some 5-6 times and Biologically fungus Alternaria affects and dries but biomass is collected there itself.Instead if you could remove the entire biomass before it flowers it will be  better option.Spreads very fast so it has to be done in a day only.

3. Thank you very much indeed for initiating discussion on water hyacinth issue in Lake Tana among scholars. I have been working seriously on this case for the last four years and produced various reports (you can find them on Bahir Dar University web site) of the weed in Lake Tana. It is rapidly expanding (more than 130 km or a third of the shoreline is infested). The lake is too shallow (8m average depth) and most of the hyacinth is rooted on the shore land and the lake has no sand beaches. Road access for heavy trucks to transport the harvested weed is limited. 

   Under this circumstance, it is possible to use small weed harvesters to reduce the biomass. The cost of operation is very high. I can imagine the interest of the community and the government is to use harvesters to quickly eradicate the weed. But from my experience sharing visit (in L. Victoria and Nile Delta), use of machine has little impact. They used weevils and they almost controlled it. 

   Use of harvesters for me is just like an anti pain to get instant relief but it can not be long lasting solution. Using harvesters could be good to reduce the current biomass, however, use of weevils (biological control) looks viable solution for Lake Tana. I share Vince Williams idea. 

    

4. By all means use biological control if cost is an issue. The water hyacinth weevil ( Neochetina eichhornia) has already been used in Africa's Lake Victoria for this purpose.  It takes a few years following introduction to gain control, but it does work.  I imaging scientists on Lake Victoria would be willing to capture adult weevils for you to inoculate your lake with an initial breeding population of 1,000 or so in cups containing 50 each.

   I worked on a large (about 45,000 ha) lake in Florida that, by the early 1970's,  received a high volume of treated sewage rich in phosphorus that helped produce about 4,500 ha of water hyacinth 'mats' in the lake's 21,000 ha littoral zone.  These mats shaded and destroyed biologically important  native plants and associated fish and wildlife and left thick organic deposits on the shallow lake bottom.  We applied for and received the very first batch of 300 hyacinth weevils divided into six styrofoam coffee cups for release at six locations.  These had been cleared for use and provided by the U.S. Department of Agriculture after that agency determined the only plant they fed on was the water hyacinth. 

   The weevils reproduce slowly, so it took about three years to see widespread visible damage the hyacinths in the release areas were visibly stressed and did not flower.  A couple more years and all the hyacinths in the lake were stressed and did not flower.  After seven years all the hyacinths were stunted and dying, and by year nine there were very few left.  The same happened in other release lakes in both Florida and Louisiana. 

   You may want to test these against your native aquatic plants and agricultural crops, or you can do a search of scientific journals to see if there are any reports of the weevil feeding on other plants.

   The weevil replaced chemical spraying (the hyacinths were spreading faster than chemical sprays killed them) and harvesting was far to expensive to consider.  The temperatures in Florida ranged from summer highs above 40 degrees C to winter lows of -10 degrees C.  These extremes did not seem to adversely affect weevil populations.

      

   1 Comment

   1. Dear sir; I realize you have little to no knowledge of modern microbiology. So may I update your understanding of what you commented on.  The clean and long term control of all waste and invasive plants is called "Bioremediation" In the early 1970,s they tried to use bacteria and some helpful fungi.  They were effective but the time took way too long and the end results were an un finished process. The reason was bacteria and fungi are DNA microbes. They do not have the genetic code for reducing compounds into their elemental/nutritional state. Only the RNA microbial group called Archaea can do this. Their activity rate of propagation is once every 20 minutes. An ocean spill takes 12 hours. The land will take no more then six weeks instead of years.  Results = 100% completion, extremely low cost, and very quick clean up time.  best of all no chemicals of any kind. RNA microbes are non pathogenic and non mutational. They are safe for the environment, the animals, fish, plants, and people. Largest users are farmers.

5. Is anyone interested in learning about the use of UVC light? We have just completed the first year of a pilot project in Lake Tahoe, CA/NV. 

   I can put you in touch with the scientists at Inventive Resourced Inc. 

6. We must respect nature,s contaminant removal plant and its growth on wetlands mus be protected 

   1 Comment

   1. Dear Islam, are you saying water hyacinth is removing contaminants and so leave the weed to florish and overtake the lake?-  if so,  it is just an absurd idea and I don't' dare to to expand on my reply with regards to the negative impacts of these bloody  weed.

      When negative impacts out way human being  always intervene.

      Kindly,

      Teshome Soressa. 

       

7. I agree to Ross Chandler  and  Miguel Angel Pavon Gutierrez . Out of the three options (i.e., mechanical, chemical and biological) I would recommend mechanical removal of water hyacinth as the best option.

8. We have a product in liquid form which can be sprayed over a covered area that will start drying the water hyacinth in 5-7 days on wards and in repeated spray of 3-4 times it will kill all the plants. Seeds of water hyacinth are the main problem for eradication from any aquatic environment. The uniqueness about this product is it not allows the seeds to be viable for next generation and ultimately it makes possible to clean the lakes and river zones. The dried mass of plants can be converted as vermicompost which will be another benefit. For more details contact me on manifisheries@gmail.com 

   2 Comments

   1. Is this Liquid spray, a chemical solution or some organic and eco-friendly liquid spray. If it is a toxic chemical, it will definately pollute the lake water.

   2. Dear Mr. Manish

      Please send technical and commercial details at

      techairmart@gmail.com 

      Mahesh Uppal

       

9. I fully support Ross Chandler's reply to the issue of Hyacinth over-growth in Lake Tana. My experience with excessive growth of macroalgae in the Peel-Harvey estuarine system as well as experience in managing algal and vegetation blooms-outbreaks in the waterways of south-western Australia, would support three practical strategies to get hyacinth under control. 1 - mechanical harvesting . There are a number of suppliers who build harvestors and attending barges to allow large harvesting operations and they can be purchased reasonably "cheaply" BUT you will need to train and develop operators to do this efficiently. You will also need to be careful about fuel supply and storage. Make sure to compost the vegetation away from the Lake with no return water able to re-gain entry into the lake and tributaries. 2 - spot applications of herbicide may work but it may be better to have human labour manually remove smaller drifts of the weed rather than load up the Lake with more nutrients and organic matter as well possible degradates of herbicide from spraying. 3 - a significant catchment and public education program will need to occur to reduce deliberate and accidental release of the weed into waterways feeding the Lake. This includes surveys around the lake to remove seeding populations in small lakes and impoundments etc that when they flood overflow into tributaries. You can contact me if you would like more information on suggestions to help remove and control this and other vegetation blooms on- tro56712@bigpond.net.au.

10. What ever you do don't spray chemicals to kill the water Hyacinth.  That will most likely lead to eutrophication of the lake killing the remaining fish stocks and making the water unsuitable for human and animal consumption.  Mechanical harvesting is the best option until you have removed the major mass, then you may spray to kill minor infestations.  Use the harvested material for compost, dry it and use it for fuel, or convert it to biochar and put that back on the farms.  The attached ref: from New South Wales, Australia may help.  It shows mechanical harvesters at work.  http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/505706/water-hyacinth-control-modules-full-accessible.pdf 

11. i have researched a cost less method method of removing water hycinth from a river or lake as per my file attached here-for more details contact me at   om.pune@yahoo.in  in india

    1 Comment

    1. Dear Singh, due to religious reasons production of pigs is not so much encouraging in here. So I am afraid to say the idea works here. But if you know some one who had interest, it could be one area to attract foreign investment with ????

12. A detailed discussion on a similar topic can be found in this forum, here:

    https://thewaternetwork.com/question-0-y/water-hyacinth-removal-from-a-river-fTZLXBLGgKzYfQ31bW9wrA

13. Control efforts should begin with mechanical harvest and use the Biomass.  This is a massive resource for conversion to energy and fertility products 

14. There are three types of water hyacinth control: Mechanical, chemical or biological.  The first two are the ones that give more rapid results for tropical high infested lakes and reservoirs (as your own example in Africa). Note, do not, I mean do not use chemical control if the water is used as a drinking source. Biological control is the less a an enviromental and antrophogenic problem issue, but it is used for mild, not excesive weed infestations, as a maintenance activity.

    In Mexico, this problem have been a tough experience, with a high nutrient level in lakes and a warm water tropical scenario.  There has been a lot of studies in relation to the possibility of gaining money  (or at least, good economical control action) with, for example, use the weed for making a compost, or a biofuel, cattle food, etc. but the reality is that --after a lot of research-- the practical use of this weed is way high more expensive and difficult that the conventional practices, so this has been a hard situation.

    Weeds are related to eutrophication problems in your lake so, besides having a strong water weed mechanical control, for example, there is the need to control the nutrients (P and N) that enter this water body, specially the waste water pollution, and other point pollutions that could be, in the first time, more easily to monitor and also to control with very low levels of nitrogen and phosphorous.  After that, you need to study your basin, and to implement good practices that limit the entrance of solids, organic matter and nutrients in your lake.

    Good luck!   Luis

    P.D.-  This article might help you,

    https://www.researchgate.net/publication/225260823_Strategies_for_waterhyacinth_Eichhornia_crassipes_control_in_Mexico

15. Under no circumstances allow any chemical spraying from air or aquatic vessel. The damage to the already severely  depleted resources may become permanent. If in a tropical forest it would recover from such deadly attacks. But a poor, arid, 3rd world country would be beyond belief.  Not to mention the begging for funds you do not need to not only resolve the issue but create and long term solution for multiple disadvantages.  

16. Biological and chemical methods may have undesirable side effects. Mechanical removal may be a good alternative as the use of a water tractor to harvest it and pile it in an area specially designed for this. The dry vegetation may be use later to create biofuels offsetting some of the cost of the removal. Monitoring and early reaction to reinfestations will be necessary to prevent this problem from getting big again.

17. If a tree grows tall you use it for shade. If you have lemons you make lemonade. If you have an invasive free floating plant on an essential natural resource in an extremely arid country you set up a composting operation. By using this harvested plant and the local organic materials you can have a great compost to build your soil for long term agricultural use. This in turn will hold the moisture in the soil. When you grow crops and or trees they respire. This increases the humidity and will cause the local climate to become suitable for tropical plant growth.  Indeed a lemons to lemonade situation. No governments, banks, or foreign investors required.  Those who stand to gain most would be ideal for the "set up" of a composting operation. The fishing industry had 13,000 tons a year now 1,000 tons. The increase in fishing alone would pay for itself in less than a year. Then you would have an ever expanding fishing, agriculture, forestry economy.  If this article is sincere please contact me for instructions. Information is always free.

18. Your options are: 1)Aerial spraying - which will give you a headstart as the area covered is already significant, then 2) biological control by releasing insects and 3) physical removal of plants. This is going to take a long time to get under control!