Page 20 - IFV Issue 4_ 2024

Estate News

Aerial photo of water hyacinth

INVASIVE ALIEN PLANTS

RAND WATER’S CONTROL STRATEGY

AT THE VAAL RIVER BARRAGE RESERVOIR

Invasive Alien Plants (IAPs) refers to plants that are non-native to an ecosystem,
which may cause economic and environmental harm or adversely affect
human health. Particularly, they impact adversely on biodiversity, including

the decline and/or elimination of native species, through competition,
predation or transmission of pathogens. This results in the disruption of local
ecosystems and their functions.

nvasive alien plants introduced
and/or spread outside their natural
Ihabitats have affected native
biodiversity in almost every ecosystem
type on earth and are one of the greatest
threats to biodiversity. Such invasions are
among the top drivers of biodiversity loss
and species extinction around the world,
with invasive species having contributed
to nearly 40% of all animal extinctions,
as suggested in a study done by Bellard,
Casey & Blackburn (2016). The problem Development stage of water lettuce Megamelus feeding on water hyacinth
continues to increase greatly from an
ecological, socio-economic and health IAPs are not static and can be the spread of IAPs such as Pistia stratiotes
point of view, worldwide. Invasive alien introduced to a new water source from (water lettuce) and Pondeteria crassipes
plants exacerbate poverty and threaten one that is impacted by birds, humans, (water hyacinth) by promoting seeding
development through their impact on boats, jet skis or any moveable object, and seed dispersal, as seen in the Vaal
agriculture, forestry, fisheries and natural via the transfer of IAP seeds, seedlings or River Barrage Reservoir (VRBR).
systems – which are an important basis plants. These can regrow asexually (i.e.
of peoples’ livelihoods – particularly in vegetatively) and sexually (i.e. seeds), How can IAPs be controlled?
developing countries like South Africa. allowing for exponential growth in the There are four methods that can be used
This damage is aggravated by climate new water source. Environmental factors to control and/or avert infestations of IAPs.
change, pollution, habitat loss and such as wind and poor water quality (i.e. These are mechanical, chemical, biological
human-induced disturbance. high organic nutrients) can exacerbate and an integrated control.

18 • Issue 4 2024 • The Villager