Invasive water hyacinth explodes on Hartbeespoort Dam

In less than two months, invasive water hyacinth has made an aggressive comeback on the polluted Hartbeespoort Dam, spreading its coverage from 5% to about 50%.

But Julie Coetzee, of the Centre for Biological Control (CBC) at Rhodes University, is confident that the tiny water hyacinth hoppers (Megamelus scutellaris) the teams rear and deploy can again successfully tackle the infestation of the world’s worst aquatic weed. 

Last year, the release of 350 000 of these biocontrol agents whittled down the cover of the fast-growing floating plant to less than 5%. “They are little soldiers doing their work with no need for thanks,” she said.

On Saturday, 82 passengers and crew of a cruise barge on Hartbeespoort Dam were safely brought to shore in a rescue operation. The Alba was disabled when the propellers became entangled in discarded fishing nets and natural debris before “being surrounded and trapped by 1.2m to 1.4m high hyacinth that surrounded the barge in natural drift while they were repairing the motors”, according to the National Sea Rescue Institute.

Hartbeespoort Dam is a “dynamic, ever changing system” that is under pressure from urban pollution and the elements, Coetzee said.