Water hyacinths are a fast growing weed that has invaded water bodies all over Africa and Asia. The dense plant covers on lakes and rivers block harbours, make fishing impossible and choke any aquatic life below. An economic, social and ecological catastrophe!
Why does it keep spreading?
Water hyacinths are native to the Amazon Basin in South America (blue). It is said that water hyacinths were first exported as ornamental plants… This way they invaded regions where they had no natural enemies (green). If nutrients and space are available, water hyacinths can double their biomass every two weeks.
So the real problem are the excess nutrients. Due to population growth and lack of waste water treatment, sewage gets directly into the lakes and rivers. Additionally, there is an overuse of fertilizers. Governments have been subsidiesing (Ethiopia) or making fertilizers available for free (Nigeria). Most of the fertilizer is washed out into water bodies… The result is fertilized water hyacinths.
Disrupts the Ecosystem...
Water hyacinths form dense plant covers that block off sunlight. They take up all the oxygen and nutrients in the in the top layer of the water bodies. Indigenous plants and algea are choked under the water hyacinths covers. There is no chance of survival…
If there are less plants and algae, it is harder for fish to find food. The fish populations decrease and start disappearing from the water hyacinths invested area.
Troubled Waters...
The water hyacinths hinder the natural flow of water through rivers. Slower currents lead to more erosion of the river beds.
At the same time, the leaves of water hyacinths give additional surface for water to evaporate. The leaves increase the total evaporation in the region that happens over plants by 40-50%. The water balance of the region is disturbed.
A real Climate Killer...
What is worse than emitting CO2? Emitting methane, CH4. When water hyacinths die off, they sink to the bottom and start decomposing. There is no oxygen available so it is an anaerobic decomposition… Like a biogas plant with noone using the biogas. All the methane goes straight into the atmosphere. As you are reading this, there are tons of decomposing water hyacinths at the bottom of lakes and rivers in 50+ countries.
An Interview with Mangustu
Hi Mangusts, Can you introduce yourself?
Hello, my name is Mangustu and I live in Shea Gomengie. It is a small village at Lake Tana, we are around 1500 households here. Most of us are fishers or farmers. I used to be a fisherman, now I am a farmer and I take any jobs that I can find around the village. The last years have been difficult.
Why are you not working as a fisherman anymore?
It has become impossible to make a living from it. The water hyacinths came here eight years ago. Since then the fish started disappearing. So four years ago I had to stop.
How was your life before the water hyacinths came?
It was much better. I used to go fishing almost every day. I went with my papyrus boat and there was no water hyacinths that blocked the access to the lake. Back then, we would catch more fish than we could carry. We had our donkeys to help us carry the full bags into the village.
What has changed since then?
It has become very difficult. There are no more fishermen in the village. I can only go fishing when the wind moves the water hyacinths away from the shore. This doesn’t happen very often and even then there are very little fish. The water hyacinths have killed them. I two kids and I need to earn money for my family.
What is your job now?
I had to become a farmer. My relatives gave me half a hectare of land, but it is still not enough to make a living. I started a small kiosk at my house to make more money. I am also taking any job I can find, but there are none in the village.
Do you have a wish for the future?
Yes, I want the water hyacinths to go. I want to be able to provide for my family again.
Why have I never heard of this?
Water hyacinths are a tropical plant. Unless you are living in a tropical area, you probably only know it as a beautiful pond flower.
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