Titus Mula, a fisherman, watches apprehensively as the floating weed draws nearer to the shore, carried by the waves.
"If this continues, in a couple of weeks the entire bay will be covered by the weed," Mula said.
The water hyacinth, a free-floating perennial aquatic plant native to tropical South America, is suffocating Lake Victoria, the second-largest fresh-water lake in the world.
"When the weed first appeared on the lake people were not concerned," he said. "We did not think the weed could pose any serious danger because of its beautiful flowers."
However, the effects started being felt in 1997 when the beaches of Dunga, Kichinjio and Hippo point in Kisumu, in western Kenya, were rendered inaccessible to fishing boats, Mula said.
The water hyacinth moves seasonally with the waves from bay to bay blocking water-ways and affecting aquatic life as it sucks oxygen from the water.
"Whenever the weed lands on our bays, our catches decline," Mula said, "The weed also entangles nets, making it difficult to fish. It becomes harder for us to catch the Nile Perch as the fish moves into the open waters away from the oxygen-deprived waters near the weeds,” he said. Tilapia is also affected, he said, with the decomposing hyacinth blocking breeding grounds.
Due to decreasing catches, the price of fish routinely goes up, he said. Early this year, the price shot up from 40 shillings (US 60 cents) to 120 shillings ($1.80), with middlemen taking advantage of the shortage to further hike prices, he said.
Blow to livelihoods
It is estimated that at least one-third of the populations of the three East African countries of Kenya, Uganda and Tanzania derive their livelihoods from the lake through subsistence fishing and agriculture.
Despite its adverse effects, the water hyacinth has, however, led to the flourishing of other fish species better adapted to less oxygenated water, including cat fish and lung fish.
The weed also provides a "closed season", preventing over-fishing in the bays it clogs up, allowing for the regeneration of the lake's fish stock as some species hide within the hyacinth.
However, according to Mula, the adverse effects of the weed far outweigh its benefits.
The weed often blocks water-intake points, affecting supplies to Kisumu and other towns on the shores of the lake, according to the regional manager of the Lake Victoria South Water Regulatory Management Authority, Margaret Abira.
"The water quality may also be affected due to the decomposition of the plant," Abira said, "which releases nutrients into the water leading to the blooming of algae, which may produce some toxic substances. This makes the treatment of water more costly as normal procedures are not as effective."
Pest control
It is estimated that the River Kagera in Rwanda carries two hectares of the weed to the lake daily, along with nutrient-rich waters from degraded catchment areas.
According to Mwende Kusera of the Kenya Agricultural Research Institute (KARI), unusually heavy rains in the catchment areas in 2006 brought in a lot of nutrients, encouraging the germination of water hyacinth seeds - hence the resurgence. The seeds can survive for at least 15 years.
 Photo: Ann Weru/IRIN  |
| Titus Mula, a fisherman from Kisumu, aboard a boat on the Kiboko beach in Kisumu |
There was a 90 percent success rate by 2005, said Jane Wamuongo, the national coordinator of the project.
However, those gains appear to be dissipating. "This is not unexpected due to the migratory nature of the weed," she said. Local community involvement in the release of the weevils has also waned.
Without project funding, it is also difficult to carry out monitoring for control, she said, adding that there was a need to reduce dependence on donor funding for sustainability.
According to Wamuongo, intervention measures need to be basin-wide, with better methods of effluent treatment and the restoration of degraded catchment areas to reduce the levels of nutrients and pollutants reaching the lake, along with harvesting and biological control.
"The water hyacinth problem is not a one-person, one-sector approach," she said.
While a long-term solution to ridding the lake of the water hyacinth is still being sought, local communities need to look into alternative uses for the weed, which could be used to generate bio-gas or as weaving material, according to an environment officer with the National Environment Management Authority in charge of Kisumu, Wilson Busienei.
"If there is a commercial use for the weed, then maybe its levels can be brought under control," he said.
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This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions
