There is danger that the Okavango Delta might be invaded by an alien aquatic menace. Without any proper mitigation strategies, the ecosystem in the Okavango is likely to be infected making it extremely vulnerable.
This was said by Susan Callum, who is a plant scientist. Whilst this has been decades in the making, plant scientists say these alien plants are slowly becoming a “blight” and there are chances they might spillover to other rivers such as Chobe.
Salvinia is the most dangerous alien species to Botswana and it invaded the Chobe River in the 1970s. This resulted in massive infestation of the lakes and perennial swamps within and outside Moremi Game Reserve of the Okavango Delta. Whilst the salvinia is still intimidating the Okavango Delta, she said there is need for sustainable monitoring of the plant species through the application of physical and biological
control methods.
“When these alien plant species enter a body of water, they quickly populate rapidly. In the process filter out algae thus effectively changing the entire ecosystem
in their wake,” she said. She further highlighted that indigenous plants are at a higher risk of extinction as a result of these invasive species and this could be disastrous for Botswana’s tourism sector which contributes a sizeable amount to the country’s GDP.
Callum also says: “the Okavango Delta is under threat from invasive species which have now become a major risk to biodiversity.
They are detrimental to the waters because they form a dense canopy which forces native plant species to be starved of sunlight and nutrients.”
She also mentioned that surrounding communities which depend on fishing for sustenance are already starting to see a notable decline in fish populations because of the imbalance caused by the plant species. This has resulted in fish populations which are low in weight and smaller in size.
Through the Aquatic Weed Control Act which was implemented in Botswana in 1986, the government controls the movement and importation of aquatic apparatus, to prevent the importation and spread of aquatic weeds both within and from the neighbouring countries.
