Teams of scientists and labourers from the Department of Water Affairs in Botswana undertook a decades old challenge since the 1970s to combat invasive weeds in wetlands of Botswana, namely the Okavango Delta, off the Kwando-Linyanti-Chobe River and the Limpopo River. Continuous monthly surveys and monitoring of rivers, lagoons and other wetlands resulted in success and shall serve as inspiration in aquatic weeds management.
The review paper "Alien Invasive Aquatic Plant Species in Botswana: Historical Perspective and Management" describes the species biology, distribution, historical spread, negative impacts, and control achieved right from their discovery in Botswana. The review presents success stories of control of salvinia, Salvinia molesta,by its biocontrol weevil, Cyrtobagous salviniae. No fresh releases of the weevil were undertaken after mass releases in 1999 and 2000,which got established in three years time. It also presents the successful eradication of water lettuce, Pistia stratiotes, in the transboundary Kwando River wetlands by 2005. Management of the growth of water hyacinth, Eichhornia crassipes, from 2012 in the transboundary Limpopo River jointly with neighboring South Africa is also addressed in the review.
The review also looks at legislation regarding aquatic weeds. The Government of Botswana "regulates the movement and importation of boats and aquatic apparatus to prevent the importation and spread of aquatic weeds" by the strict implementation of "Aquatic Weed (Control) Act -1986".
The efforts made by the department have benefited tourism, water resource use, and wildlife. Partly due to the achievement of aquatic weeds control, the tourism sector is now very stable and contributes ca. 25% to the country's GDP.
The authors Kurugundla et al. suggest that integrating biological and physical control with public awareness campaigns while working with conservation groups and NGOs would provide sustainable development of wetlands for ecological integrity and livelihoods.
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Reference: Kurugundla. C. N.; et al. (2016). Alien Invasive Aquatic Plant Species in Botswana: Historical Perspective and Management, Open Plant Sci. J., DOI: 10.2174/1874294701609010001