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42
Poster Session
Detecting Xenopus laevis in Belgium using eDNA and qPCR
Sophie Gombeer1, Kenny Meganck2, Ann Vanderheyden1, Nathalie Smitz2, Olivier Pauwels3, Jonathan Brecko3, Marc De Meyer2, Thierry Backeljau1,4
1Royal Belgian Institute of Natural Sciences, BopCo, Belgium; 2Royal Museum for Central Africa, BopCo, Belgium; 3Royal Belgian Institute of Natural Sciences, Scientific
Heritage Service, Belgium; 4University of Antwerp, Evolutionary Ecology Group, Belgium
Environmental DNA (eDNA) has become an essential tool in the search for and detection of invasive species. In aquatic environments, water samples
can be collected and filtered after which DNA can be extracted and analysed to detect the presence of a target species using quantitative PCR (qPCR).
The African clawed frog (Xenopus laevis) is such an aquatic invasive species of amphibians imported from South Africa for medical research and
aquarium pet trade. Released from capture, on purpose or by accident, an invasive spread of Xenopus laevis to natural ecosystems was registered on
most continents. In the absence of natural predators, their population densities can increase quickly causing damage to local aquatic ecosystems. The
species is easily distinguished, but not as easily discovered compared to the native amphibians, preferring to hide under plants and burrowing in the
soil at the bottom of freshwater lakes or ponds.
Two historical occurrence sites with one-time observations are known in Belgium so far: the Antwerp University Campus Drie Eiken, Wilrijk (2008) and
Le Bizet, Komen-Waasten (2016), with suitable conditions for further natural spread. Using eDNA and qPCR techniques, we surveyed on and around
these sites aiming to (i) investigate if the species is still present at these sites and (ii) examine if a natural spread towards the nearby ponds and
streams occurred.
Water samples were collected in triplicate from multiple water bodies (2021) and a species-specific qPCR assay to detect the African clawed frog
was performed. Positive samples were sequenced to verify the qPCR outcome. The methodologies, our initial results and a preliminary conclusion
will be presented.
Tuesday, April 19, 2022
Assessing management efficacy of a multiple herbicide treatment plan on Ludwigia Peploides
and Hydrocharis morsus-ranae in a freshwater community
Ashley Morris1,2; Catherine McGlynn1; Steven Pearson1; Nicole White1
1New York State Department of Environmental Conservation, USA; 2Stony Brook University, Department of Ecology and Evolution, USA
Several different species of aquatic invasive plant grow in the Peconic River (Suffolk County, New York, USA). Co-occurrence of these species presents
unique management challenges as each target species has a different life history and set of interactions with the surrounding community of native
and invasive plants. Management plans integrating multiple herbicides can target several invasive species in a system at once and could potentially
have positive effects on the reclamation of the environment by native species. The removal of multiple highly competitive invasive species could allow
for a less competitive native to move into the newly vacated niche space. Additionally, combining multiple herbicides will mitigate the development
of resistance to single chemical treatments, making long term treatments potentially more effective. New York State Department of Environmental
Conservation tested this approach by conducting a small (0.97 acre) pilot study in the Peconic River system on Long Island, NY. The main goal of this
treatment was to determine how a combination of the herbicides, florpyrauxifen-benzyl (ProcellaCOR®) and imazamox (Clearcast®), affected the small
population of Ludwigia peploides and its surrounding community of other invasive and native plants. In 2022 the treatment area will be expanded to
incorporate the entire freshwater portion of the river and focus on both Ludwigia peploides and Hydrocharis morsus-ranae. The native species response
to this duel herbicide treatment will be tracked through a series of vegetation surveys of the treatment sites as well as the surrounding river system.
Special consideration will be paid to the native species (emergent and floating) that would be expected to be released from competition with these
invasive species. This project will provide insight into the recovery of native plant populations and the long-term efficacy of passive restoration efforts.