African Wildlife & Environment Issue 74

CONSERVATION

South Africa - UK partnership for the early detection of aquatic invaders using ENVIRONMENTAL DNA

By Dr Bezeng Simeon Bezeng & Professor Vincent Savolainen

There is a long history of scientific collaborations between South Africa and the UK, especially through co-funding from the South African National Research Foundation and the British Royal Society. One important scheme is the Newton Fund, launched in 2014, which is an initiative that aims ‘to develop the long-term sustainable growth and welfare of partner countries through building research and innovation’.

I n particular, the Newton Fund helps strengthen the research and innovation capacity of early- career researchers from partner countries (in our case South Africa) by linking them with the best researchers in the UK and by providing support for initial exploratory research. Furthermore, it aims to establish long-term research links between both partners to ensure sustainable research capacity. Through this opportunity, Dr Bezeng (South Africa) and Professor Savolainen (UK), having collaborated before on invasion biology, found the need to strengthen further research ties by exploring new advances in molecular sequencing techniques to detect invasive species at ports of entry in South Africa. Our idea was to use DNA technology to identify potential invasive species carried by vessels moving around the world and finally entering South Africa’s ports. This is especially important because South Africa is a gateway for many species entering the African continent. As vessels travel to South Africa, their tanks are often filled with water (called ‘ballast water’) to improve their stability. However, this ballast water sometimes contains hundreds of living organisms, which can be transported unintentionally to other parts of the world as ships travel. This is partly because the living organisms present in this ballast water cannot be seen with the naked eye, or if visible, they cannot be easily identified when they are at a larval stage (such as fish and invertebrates). If they arrive unnoticed, some of the living organisms can then cause significant damage to local biodiversity

and ecosystems, and they are very costly to remove. Worldwide, biological invasions are indeed a major problem, both ecologically and economically. For example, in the US alone, invasive species are detrimental to global economies, calculated to exceed US$130 billion annually (nearly two trillion Rand). Therefore, understanding the mechanisms that predispose non-native species to become invasive has been challenging to biologists, primarily because of problems inherent to species identification and early detection. South Africa faces one of the biggest challenge of species introduction, and potential invasions, of many hundreds of non-native invertebrates and >8,000 plant species have been documented, but the economic impacts of such events are not fully understood. Although South Africa is now developing ‘early warning’ programmes to identify non-native species upon arrival in order to prevent their subsequent spread, this isdifficult giventhatmostnon- native species usually reach their new destinations in juvenile stages, as cryptic species or present in low numbers. This is especially true for marine animals where large areas of the South African coastline remain unmonitored. In addition, taxonomists are in short numbers; the latter a problem not specific to South Africa. Therefore, across the globe, scientists have turned to DNA techniques to provide rapid and accurate identification of living organisms. An initial method, called ‘DNA barcoding’ used short and standardised gene fragments as species identifier. However, this barcoding technique has had its limitations, especially in cases where samples

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