Delta Park dam now ‘99.9% clear’ of invasive water hyacinth

The Delta Park Users Group has announced that the Florence Bloom Dam in Delta Park is 99.99% clear of the water hyacinth that had taken over the body of water.

The Randburg Sun reported in February that efforts to remove the hyacinth began after the invasive plant completely covered the Delta Park dam as a result of a six-week sewer leak.

Water hyacinth, originally from South America, loves nutrient-rich water. Sewage spills provide nitrates and phosphates that the plant thrives on.

What’s the problem with water hyacinth?

While the aquatic plant produces a beautiful flower, it can double its biomass every 10-14 days under the right conditions. More worryingly, the mats of water hyacinth block out the sunlight. This in turn prevents submerged plants and phytoplankton from photosynthesising, starving the water of oxygen.

“If there is no oxygen left in the water, most of the organisms living in the water body die,” notes Shirley Tebbutt, the Delta Park Users Group leader.

“So, fish, insects, crabs, snails, etc. that need to take up oxygen from the water column are negatively affected.”

Tebbutt and her team finally won the long battle against the hyacinth, after initially releasing “hyacinth hoppers” – natural enemies of the water hyacinth – into the dam.

Members from the South African Institute for Aquatic Biodiversity (SAIAB) and the Centre for Biological Control (CBC) introduced these insects as bio-control agents.

A team effort

While these insect allies are very effective in killing off the invasive plant, the hyacinth problem was just too great.

So Tebbutt decided to go back to what they did in the top dam in 2005, and take the plants out manually.

“At first it seemed a bit daunting with my one canoe, but after a plea for more canoes, we were loaned a long blue one,” Tebbutt said.

“It was named The Barge, because of the huge amount it could hold.”

The team were also aided by a tractor loader backhoe (TLB) to remove swathes of hyacinth, while donations and volunteers have helped speed up the project. Eventually a team of 11 people were working daily to remove the problematic plant.

“I contacted a contractor; he gave me day [to use the TLB] for free,” Tebbutt added. “It has been a huge success, but without all the kind and generous donations, it would never have happened.”

source:Delta Park dam now ‘99.9% clear’ of invasive water hyacinth (thesouthafrican.com)