Durban - Clumps of exotic, invasive water hyacinth flowing to their demise as they meet the waves of the sea off Blue Lagoon has been a common sight in the recent wet season.
There are not many other natural ways the plant is controlled in South Africa, where rivers are without the natural predators such as weevils and moths that keep it at bay in its home habitat in South America. Nor are there manatee, which forage on water hyacinth in the Amazon.
Water hyacinth can also cause more flooding because it blocks channels.
It also deprives waterways of sunlight and oxygen, and blocks access to water.
That’s what has happened on the lower reaches of the eManzimtoti River.
“We moved a lot on Sunday and we worked out that using shadecloth (as a net) works best,” said Shaun Callaghan, driver of a community initiative to clear the weed from the river, where it passes through a green lung that includes the Ilanda Wilds Nature Reserve.
Multiple groups plan to repeat the exercise tomorrow.
Callaghan believes that a dysfunctional sewerage system is the root cause of the proliferation of hyacinth in his town’s river, providing nutrients that the floating plants soak up.
He also said a weir, built to raise the water level on the lagoon, impacting on the flow of water in the river, has encouraged the plant’s growth in stagnant water.
An eThekwini Municipality report mentions the weir as one of the numerous human interventions that has compromised biodiversity.
Six years ago, Callaghan was involved in a previous clean-up, only to see a regrowth six months later and the sight of dying fish and birds when manholes once again overflowed.
"This time around, older people said they had never seen hyacinth this big," he said, suspecting that there must have been a serious spewing out of sewage from manholes near the eManzimtoti River.
Water hyacinth thrives, spreading with speed.
Three rivers up the coast and many bends inland along the course of the uMlazi, but still within the municipality, a conservation organisation is spearheading an initiative to turn the problem plant into an asset for the population around the Shongweni Nature Reserve, inside which is the Ntshongweni Dam.
This is in line with a move away from the colonial, linear approach to working together with such communities, aiming to achieve the United Nations Sustainable Development Goals and offering alternatives to unsustainable practices, said Greg Vogt, director of Conservation Guardians, which mentors the community that owns the reserve.
His proposed solution is drying out water hyacinth and charring it to become charcoal and a compost that can be used to improve people’s livelihoods, while being an alternative to practices that put them in conflict with the nature sanctuary.
“Women chop trees down because they want to take the wood and use it to make their (home) fires. We say, rather let’s teach them how to make briquettes.”
Making the briquettes involves using a charcoal oven that cooks the dried out plants to 500°C and a simple mould to compress the briquette.
He expects it will take time to catch on bu,t from next month, the braai-ing public should be able to buy them at the Shongweni Farmers Market.
Another conflict between conservation and community in the Shongweni Nature Reserve involves cattle grazing in the nature reserve and the burning of reserve land to encourage the growth of green shoots for these livestock.
“The cattle also create their own paths, compete with the plains game and bring in seeds from outside,” said Vogt.
Work is under way to produce livestock feed from hyacinth, as well as compost that will, hopefully, enrich the soil in the surrounding community’s fields and vegetable gardens, thus reducing the incentive for them to be driven into the park.
Water hyacinth is a complex plant and processing it for positive use requires some special care.
“It has an amazing ability to absorb toxins and heavy metals,” explained Vogt.
That’s why the plants must be dried before charring.
Sitting at his humble base and using scant resources, Vogt has taken to social media to exchange notes about dealing with water hyacinth with other people around the world.
One is German agricultural engineer and entrepreneur Walter Danner, who does voluntary work for the NGO Char2Cool, which aims to use biochemistry to cool the world climate.
He has worked in Nigeria, where ferries could not move in Lagos harbour because strings from water hyacinth roots were getting stuck in the rotors. He has also worked on the problem in Ethiopia’s Lake Tana, the source of the Blue Nile.
In a telephone interview, Danner told The Independent on Saturday said he had a dim view of politically-driven eradication campaigns.
“When water hyacinth is sprayed with pesticides, it dies and produces methane and carbon dioxide, which are released into the atmosphere. These are severe climate gases. They harm the climate with spraying and cause a lot of money to be spent on climate destruction.”
Danner stressed that water hyacinth would not just go away, no matter how much one removed it.
“But its products provide jobs, food security and prosperity for locals around water bodies.”
By the time of going to press, the eThekwini Municipality had not replied to questions about the sewage issues in eManzimtoti, nor about its approach to water hyacinth.
The Independent on Saturday