A NEW THREAT TO THE VAAL RIVER
Water Lettuce, an invasive alien species, has made its appearance in the Vaal River for the first time. It was noticed in the Suikerbos River at its confluence with the Vaal River at Vereeniging recently. Rand Water, the custodian of the Vaal River in this area, was informed.
The opening of the Vaal Dam sluice gates has facilitated the rapid spread of water lettuce as a result in the fast-moving water in the Vaal River travelling downstream of Vereeniging. This noxious weed can cause serious damage to our precious water resource, sapping oxygen and causing serious damage to aqua life. it. Its leaves are poisonous and can cause intense internal disturbances in humans and animals.
Water expert, Anthony Turton said: “Both water hyacinth and water lettuce are
manifestations of Eutrophication. ‘We have never been able to reverse that process once it gets out of hand”. He also noted that water lettuce had not been an issue in Gauteng but is a major problem in KZN. The Conservation of Agricultural Resources Act 43 of 1983 (Regulation 15 and 16) as amended, provides for the removal of aquatic weeds from any land or water body by the owner or person responsible for the management thereof. This indicates that it is Rand Water has a responsibility to get rid of water lettuce within its area of jurisdiction of the Vaal River.
The free-floating, aquatic perennial plant seldom exceeds 150-200mm in diameter.
The plants consist of a rosette of leaves and a tuft of long, fibrous roots beneath and it resembles floating lettuces. The leaves are pale yellow-green, narrower at the base and round, straight or notched at their tips, ribbed, with many longitudinal veins radiating.
Water Lettuce’ invasive status in South Africa is a Category 1b plant and must, therefore, be removed from land and water. Water lettuce forms dense mats which completely cover and clog a water surface and reduce water flow, thus impeding fishing and other recreational activities. It is also a breeding ground for mosquitoes and bilharzia-carrying snails.