Page 36 - Waterfall City Issue 5 May 2024

Waterfall City Nature

Aerial photo of water hyacinth in the Vaal River Barrage Reservoir

INVASIVE ALIEN PLANTS

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

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.

I nvasive alien plants introduced

and/or spread outside their
natural habitats 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 Development stage of water lettuce Megamelus feeding on water hyacinth
problem continues to increase greatly
from an ecological, socio-economic climate change, pollution, habitat loss seeds), allowing for exponential growth
and health point of view, worldwide. and human-induced disturbance. in the new water source. Environmental
Invasive alien plants exacerbate factors such as wind and poor water
poverty and threaten development IAPs are not static and can be quality (i.e. high organic nutrients) can
through their impact on agriculture, introduced to a new water source from exacerbate the spread of IAPs such
forestry, fisheries and natural systems one that is impacted by birds, humans, as Pistia stratiotes (water lettuce) and
– which are an important basis of boats, jet skis or any moveable object, Pondeteria crassipes (water hyacinth)
peoples’ livelihoods – particularly via the transfer of IAP seeds, seedlings by promoting seeding and seed
in developing countries like South or plants. These can regrow asexually dispersal, as seen in the Vaal River
Africa. This damage is aggravated by (i.e. vegetatively) and sexually (i.e. Barrage Reservoir (VRBR).

34 Waterfall City Issue 5 2024