Conservancy to root out water hyacinth

IN an ongoing project at the Giba Gorge Mountain Bike Park, staff have taken extra effort to reduce the water hyacinth population in one of its dams.

Just a few metres away from a beautiful waterfall in the conservancy are two, large man-made dams.

One is infested with water hyacinth and three of the park’s workers were manually removing the alien invasive plants in an effort to weaken its stranglehold on the dam’s fauna and flora.

Wilbur Mahlamvu, the environmental manager and the chairman of the Giba Gorge Conservancy, said the alien plant was brought into the country for its beauty but has since caused havoc in local rivers and dams. “The water hyacinth is an aquatic plant and can completely cover large areas of water.

“The danger here is that fish can’t breathe properly, their predators can no longer feed and it is a danger to indigenous plants,” he said.

The water hyacinth removal project started in 2006.

“We are able to pull out about 500 of these plants, per person, per day. We then allow them to die completely by leaving them out in the sun. This can take up to three months,” said Mahlamvu.

There are also plans to set up a worm farm to help decompose the water hyacinth which has already been removed from the dam.

Last Wednesday, a host of 3 300 biological control bugs were released onto the carpet of water hyacinth.

This was to help control the growth of its population and allow the staff members a chance to remove the rest of the plants manually.

“Upon release they won’t make a huge dent on the water hyacinth population as the most devastating part of the water hyacinth weevil’s life cycle is the larvae stage,” said Des Conlong, an entomologist for the South African Sugar Association.

Only a handful of the plants flowered this year and Conlong said it was due to the previous bugs that were released at the dam.

“The plants are under stress and many are not flowering. This will help reduce the seed bank, which is viable for up to nine years,” he said.

One of the Park’s owners and founders, Chris Harburn, said this would be an ongoing project and his staff were hard at work removing the alien plants that are dotted throughout the expanse of the conservancy.

Harburn said they would release another group of insects at the site in about two weeks.

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