Page 34 - Intra Muros May 2024

NATURE

INVASIVE ALIEN PLANTS

Rand Water’s Control Strategy at the Vaal River Barrage Reservoir (VRBR)

Aerial photo of water hyacinth in the Vaal River Barrage Reservoir.

Invasive Alien Plants (IAPs) are plants that are non-native to an ecosystem, which may cause economic and
environmental harm or adversely affect human health. Particularly, they impact 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/ any moveable object, via the transfer of IAP (i.e. high organic nutrients) can exacerbate
or spread outside their natural habitats seeds, seedlings or plants. These can regrow the spread of IAPs such as Pistia stratiotes
Ihave affected native biodiversity in asexually (i.e. vegetatively) and sexually (i.e. (water lettuce) and Pondeteria crassipes
almost every ecosystem type on earth seeds), allowing for exponential growth (water hyacinth) by promoting seeding and
and are one of the greatest threats to in the new water source. Environmental seed dispersal, as seen in the Vaal River
biodiversity. Such invasions are among the factors such as wind and poor water quality Barrage Reservoir (VRBR).
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 continues to increase
greatly from an ecological, socio-economic
and health point of view, worldwide.
Invasive alien plants exacerbate poverty
and threaten development through their
impact on agriculture, forestry, fisheries and
natural systems – which are an important
basis of peoples’ livelihoods – particularly in
developing countries like South Africa. This
damage is aggravated by climate change,
pollution, habitat loss and human-induced
disturbance.

IAPs are not static and can be introduced
to a new water source from one that is
impacted by birds, humans, boats, jet skis or

32 | INTRAMUROS MAY 2024