eDNA reveals hidden crested newts and advancing invasive clawed frogs
There’s both promising and troubling news from the Douvebeek Valley in Belgium’s Westhoek region. Environmental DNA (eDNA) research has revealed an unexpected high number of sites harbouring the European protected crested newt. However, the same survey showed that the invasive African clawed frog is rapidly spreading in the same area, posing a significant threat to this vulnerable native species.
The African clawed frog, native to South Africa, was first spotted in northern France in 2018. Subsequent large-scale surveys in the region revealed established populations in both Flanders and Wallonia. This frog is highly invasive and feels at home in almost any freshwater habitat. To monitor its spread, we conducted a large-scale eDNA monitoring in pools and streams near the border. We found not only the presence of clawed frog DNA, but also detected crested newts in numerous locations, previously unknown to harbour this species.
Despite this positive discovery, there is cause for concern. The eDNA results indicate that African clawed frogs are present in many more pools than expected, and that they are increasingly encroaching upon the crested newt’s habitat. In several locations, the eDNA results suggest both species co-exist in the same pond at several locations. Given the documented negative impact of this invasive alien species on native fauna elsewhere in Europe, urgent and targeted action is necessary. A coordinated cross-border management strategy will be crucial to safeguard native biodiversity and protect these newly discovered crested newt populations.
Rein Brys, Teun Everts, Jeroen Speybroeck, Loïc van Doorn, Maud Segal & Tim Adriaens
Image above: clawed frog (left) and crested newt (right), photos by Jelger Herder