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Environmental DNA sampling for African clawed frog in Flanders, Wallonia and France in 2020 Loïc van Doorn, Jeroen Speybroeck, Tim Adriaens, Rein Brys

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Authors: Loïc van Doorn Jeroen Speybroeck Tim Adriaens Rein Brys Research Institute for Nature and Forest (INBO) Reviewers: Johan Auwerx The Research Institute for Nature and Forest (INBO) is an independent research institute of the Flemish government. Through applied scientific research, open data and knowledge, integration and disclosure, it underpins and evaluates biodiversity policy and management. Location: Herman Teirlinckgebouw INBO Brussel Havenlaan 88 bus 73, 1000 Brussel vlaanderen.be/inbo e-mail: loic.vandoorn@inbo.be Way of quoting: van Doorn, L., Speybroeck, J., Adriaens, T. & Brys, R. (2022). Environmental DNA sampling for African clawed frog in Flanders, Wallonia and France in 2020. Reports of the Research Institute for Nature and Forest 2022 (6). Research Institute for Nature and Forest , Brussels. DOI: doi.org/10.21436/inbor.71707757 D/2022/3241/045 Rapporten van het Instituut voor Natuur- en Bosonderzoek 2022 (6) ISSN: 1782-9054 Responsible publisher: Maurice Hoffmann Cover photograph: Loïc van Doorn

This work is licensed under a Creative Commons Attribution 4.0 International License.

ENVIRONMENTAL DNA SAMPLING FOR AFRICAN CLAWED FROG IN FLANDERS, WALLONIA AND FRANCE IN 2020 Loïc van Doorn, Jeroen Speybroeck, Tim Adriaens, Rein Brys

doi.org/10.21436/inbor.71707757

Abstract In 2018 a population of African clawed frogs (Xenopus laevis) was discovered in a single pond in La Chapelle-d’Armentières, France, located 2,5 km south of KomenWaasten, Wallonia, Belgium and 5,3 km southeast of Heuvelland, Flanders, Belgium. To assess the potential presence of this species in Belgium, 74 samples of water bodies in Flanders, 23 in Wallonia and 9 in France were analysed for presence of X. laevis DNA in April 2020. Results indicate that X. laevis is not present in the prospected sites in Flanders and Wallonia at this time, whereas a strong positive signal was detected in the pond harbouring the source population in France. If the species manages to invade Belgium in the future, successful eradication will prove to be difficult and costly. Swift action in France, including, but not limited to, draining of occupied water bodies, combined with fencing and extensive environmental DNA (eDNA) screening of additional water bodies within dispersal distance is urgently needed to prevent such invasion. Furthermore, monitoring of eradication success via eDNA is recommended for several years after eradication measures have ceased.

Résumé En 2018 une population de Xénope lisse a été découverte dans une seule mare à La Chapelle-d'Armentières en France, située 2,5 km au sud de Komen-Waasten en Wallonie, Belgique et 5,3 km au sud-est de Heuvelland, Flandre, Belgique. Pour évaluer la présence potentielle de cette espèce en Belgique, 74 échantillons de plans d'eau en Flandre, 23 en Wallonie et 9 en France ont été analysés pour la présence d'ADN de X. laevis en avril 2020. Les résultats indiquent que X. laevis n'est pas présent dans les sites prospectés en Flandre et Wallonie à cette époque, alors qu'un fort signal positif a été détecté dans l'étang abritant la population source en France. Si l'espèce parvient à envahir la Belgique à l'avenir, une éradication complète sera difficile et coûteuse. Une action rapide en France, y compris, mais sans s'y limiter, le drainage des masses d'eau occupées, combinée à des clôtures et à un dépistage étendu de l'ADN environnemental (ADNe) de masses d'eau supplémentaires à distance de dispersion est nécessaire de toute urgence pour empêcher une invasion. De plus, le suivi du succès de l'éradication via l'ADNe est recommandé pendant plusieurs années après l'arrêt des mesures d'éradication.

Samenvatting In 2018 werd een populatie Afrikaanse klauwkikkers (Xenopus laevis) ontdekt in één poel in La Chapelle-d’Armentières in Frankrijk, 2,5 km ten zuiden van Komen-Waasten, Wallonië en 5,3 km ten zuidoosten van Heuvelland, Vlaanderen. Om het potentiële voorkomen van deze soort in België na te gaan, zijn 74 waterlichamen in Vlaanderen, 23 in Wallonië en 9 in Frankrijk geanalyseerd voor X. laevis DNA in april 2020. De resultaten tonen aan dat X. laevis momenteel niet voorkomt in de onderzochte locaties in Vlaanderen en Wallonië, maar een sterk positief signaal werd gedetecteerd in de poel waar de bronpopulatie zich bevindt in Frankrijk. Als deze soort zich in de toekomst in België kan vestigen, zal succesvolle eliminatie moeilijk en kostelijk zijn. Snelle actie in Frankrijk, door onder meer het leegpompen en omheinen van besmette wateren en een doorgedreven environmental DNA (eDNA) onderzoek van bijkomende waterpartijen binnen dispersie-afstand is dringend nodig om deze invasie tegen te gaan. Daarnaast is ook de monitoring van beheersingrepen gedurende enkele jaren via eDNA aangeraden. ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Page 2 of 17

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Recommendations for management and/or policy African clawed frogs are thought to be absent from the Flemish areas bordering the French population at the time of sampling (spring 2020). Additional comprehensive eDNA sampling in Wallonia and France is advised, as only a subset of water bodies were sampled. The results from our in depth sampling campaign indicate that the species is still in the early stages of invasion. Thus, the time to act in France is now, considering the financial and ecological consequences of further delay. Conservation importance of the pond in which the reproducing population is located is negligible. The pond is in the early stages of succession, submersed vegetation is largely absent, and the presence of both fish (Pungitius pungitius) and African clawed frogs have reduced the suitability of the habitat for both invertebrates and the few native amphibian species (Pelophylax sp., Lissotriton vulgaris, Ichthyosaura alpestris, Bufo bufo and Rana temporaria) co-occuring in the pond. The pond is well-suited for complete drainage, with steep slopes and deeper areas. Combined with a drift fence completely surrounding the pond, to ensure no animals escape, a quick and thorough draining of the pond is the best option to increase efficacy of the mitigation measure and minimize workload and financial investment. Optimally, drainage occurs before the African clawed frogs become more active in spring, in this way potential emigration risks are further reduced and the impact on native amphibians is reduced. After complete removal of all life stages of X. laevis, if necessary through repeated draining of the pond, a thorough eDNA campaign during the next spring including stagnant, temporary, and running water bodies within an area of at least 5 km surrounding the pond should be paramount, to ensure no unnoticed populations persist in the wider surroundings. If detected, these locations should be dealt with accordingly. After all infected sites are cleared of the species, eDNA sampling should be repeated periodically for 5 years to ensure this invasive species does not regain a foothold.

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Table of contents Abstract

Recommendations for management and/or policy

List of figures

List of tables

Introduction

Materials and methods

Field sampling

Laboratory analyses

Results

References

Appendix

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List of figures Figure 1

Infected pond in La Chapelle-d’Armentières ...................................................... 7

Figure 2

African clawed frogs removed from a pond in La Chapelle-d’Armentières ....... 8

Figure 3

eDNA sampling locations in spring 2020............................................................. 9

Figure 4

A subset of sampling locations during the 2020 survey ................................... 10

Figure 5

ddPCR output of a subset of field samples ...................................................... 11

Figure 6

ddPCR output of a positive and negative control sample included at each run, four negative field samples, and two positive samples ................................... 12

List of tables Table 1

Merged table containing samples and metadata for the 2020 campaign and observations of Xenopus laevis ......................................................................... 14

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Introduction The African clawed frog Xenopus laevis, native to Sub-Saharan Africa, was introduced to natural systems around the globe. Introductions originate from escapes or releases linked to the pet trade and from laboratories that use animals as model organisms in developmental and cellular biology (Measey et al. 2012). There are several physiological and demographic traits that can explain the success of the species as an invasive species. Xenopus laevis has a largely aquatic ecology, can adapt to a wide range of (anthropogenic) habitats, tolerate temperature fluctuations, salinity and pollution. It is able to burrow itself in the substrate, thereby persisting unfavourable conditions such as drought periods (Sousa et al. 2018). Apart from aquatic migration, the species is able to disperse over land (Measey 2016). Furthermore, this species has large clutch sizes (up to 17.000 ova/female) and can reproduce several times per year and can attain an age of at least 15 years. In a global review of alien amphibian impacts Xenopus laevis was ranked second (after cane toad Rhinella marina) among the seven amphibian species part of the ‘100 of the world’s worst’ invasive species, based on its environmental and socio-economic impacts (Measey et al. 2016). Xenopus laevis is a generalist aquatic carnivore, predating on invertebrates, amphibians, fish and smaller vertebrates. Invertebrates and native amphibian species have been shown to decline when co-occurring with X. laevis (see Scalera et al. 2019 and references therein). Furthermore, X. laevis is a known vector for amphibian diseases. A risk assessment has been performed for the European Union (Scalera et al. 2019), and based on the results the species is currently (January 2021) under consideration for regulation under the European Union IAS Regulation (1143/2014). In Europe, the species is presently established in France, Portugal and Italy (Sicily) and has been recorded in six additional countries. In Belgium, three observations are documented, but no established populations are currently known. In France, African clawed frogs were introduced in the 1980ies, in the Two-Sèvres region, following the closure of a breeding centre and 30 years later occupy an area of over 2000 square kilometres (Louppe et al. 2017). The French populations are under management in the framework of the EU co-funded Life project CROAA (Control stRategies Of Alien invasive Amphibians, 2016-2022) LIFE15 NAT/FR/000864 (www.life-croaa.eu/). In September 2018 a population was reported in La Chapelle-d’Armentières (département du Nord, région Hauts-de-France, Lille), in a 0.25 ha permanent pond (figure 1) owned and managed by the municipality, at about 2,5 km from the border with Belgium (Labadesse & Quevillart 2020).

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Figure 1:

Infected pond in La Chapelle-d’Armentières, France. November 2020 (Loïc van Doorn).

Important, protected wetlands areas in the vicinity include the nature reserve of Ploegsteert (100ha), a marsh area with old clay pits. Also relevant is the Valley of the Lys which could potentially serve as a dispersal route into Belgium. In La Chapelled’Armentières, the species is reproducing as adults and larvae of different cohorts have been found (figure 2). Observations of the species in 2006 and in 2016 in KomenWaasten on the Walloon side of the border were reported on the citizen science portal www.observations.be. In response to this newly discovered population in France, a working group of relevant French and Belgian actors was founded in 2019 to discuss potential mitigation actions. Submerged fyke trapping was performed between September and November 2020. Four isolated water bodies within 1km were visually surveyed for the species and eDNA samples were taken from these locations. Considering the invasive character of the species and its potential impact on native amphibians, nearby protected wetland areas, dispersal corridors via the river valley at just a few kilometres from the site and the presence of a large metapopulation of the protected great crested newt (Triturus cristatus) just across the border in Flanders, in April 2020, INBO decided to perform a landscape-scale eDNA sampling in a buffer area around the known population in France and the casual records in Wallonia. This short report describes the results of this initial survey, that can serve as a baseline for future surveillance initiatives.

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Figure 2:

African clawed frogs removed from a pond in La Chapelle-d’Armentières, France. A) Subset of larvae caught in October 2020. Note the unique morphology, different stages of development, and the albinistic individual. Larvae are pelagic filter feeders and school together in deep parts of the pond. B) Adult male (left) and female (top) caught with submerged fykes in November 2020. Note the pronounced sexual size dimorphism in this species (Loïc van Doorn).

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Materials and methods Field sampling Environmental DNA (eDNA) sampling was performed on the 21st and 25th of April 2020. In total 74 water bodies (ponds, drainage ditches, canals and lakes) were sampled in Flanders, 23 in Wallonia and 9 in France, mostly lakes (figure 3, appendix table 1). Samples were taken in a standardized approach. In most cases, subsamples from several water bodies located close to each other (clusters) were pooled to obtain a single integrated and homogenous sample. For Flanders, this amounts to 23 pooled samples, for Wallonia 6, and for France 5. The water bodies were thoroughly sampled with subsamples of 0,5L scooped from the complete surface area just below the water surface, using a telescopic sterile pole with a sterile bag attached at the end (figure 4). A strict hygienic protocol was followed to exclude sample contamination and to eliminate the potential spread of pathogens.

Figure 3.

eDNA sampling locations in spring 2020. To decrease workload while maintaining a high landscape coverage, several water bodies in close proximity were pooled in one sample. Different lines that are connected with these pooled sample locations point on the water st bodies in which subsamples are taken. Samples taken on the 21 of April in black, on the th 25 in blue. Reported observations of X. laevis are presented in green, the known population in La Chapelle-d’Armentières in orange (see appendix table 1 for precise locations).

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For each pooled sample, new sterile equipment was used, and 2% Virkon S (Antec DuPont, Suffolk, UK) was used to decontaminate all reusable field material in between sampling locations. The collected samples were filtered in the field using enclosed Sterlitech filters (50 mm diameter syringe disk filter with an integrated 5 µm glass fiber prefilter and a 0.8 µm PES membrane) and a peristaltic pump, allowing a larger amount of water to be filtered. After filtration, the remaining water inside capsules was expelled by forcing air through the capsule. In a next step each filter was capped at both ends, and stored at −21°C in anticipation of further analyses in the laboratory. During field sampling field blancs were included in the workflow (i.e., filtering following the same procedures but with clean, uncontaminated source water).

Figure 4.

A subset of sampling locations during the 2020 survey. Note the use of the telescopic pole with an attached 0.5L bag allowing for better coverage of the water body surface. All equipment is sterilised between clusters/pooled locations.

Laboratory analyses Prior to PCR, all eDNA samples were stored and processed in a PCR-free building at INBO, dedicated to low copy number template extractions, with controlled DNA-free high-efficiency particulate air (HEPA)-filtered compartments with positive pressure to prevent eDNA sample contamination. On each filter an internal positive control (IPC) was added in the first step of the extraction together with the lysis buffer, in order to test for potential inhibition and thus to avoid false negative detections (see figure 5 and 6) to evaluate extraction efficiency of each sample separately. This IPC is a plasmid with a 149 bp insert sequence from Dengue virus type 2 (GenBank M29095.1) and can be quantified with a primers/probes assay with droplet digital PCR (ddPCR). This assay is compatible to run in duplex with the primer/probe assay for the target species.

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Figure 5.

ddPCR output of a subset of field samples, showing optimal amplification of both the Internal Positive Control and Target eDNA in sample 1, whereas sample 2 and 3 illustrate complete and substantial inhibition in the 1:1 and 1:2 dilution respectively.

In a next step, each of the filters was recapped and placed in a rotating incubator overnight at 56 °C. The DNA was extracted from the filters using Qiagen’s DNeasy Blood & Tissue Kit according to the manufacturer's instructions. DNA extracts were additionally purified with the DNeasy PowerClean Cleanup Kit (Qiagen) according to the guidelines provided by the manufacturer, and were eluted in 100 µL of TE. Comparing the concentration of IPC initially added to each filter and finally quantified by ddPCR after extraction or cleaning up, allows to standardize variation in target eDNA concentrations attributable to sample-specific differences in DNA extraction or amplification efficiency and hence to increase the comparability of eDNA samples in space and time. During the lab workflow several technical blancs and positive reference samples were included, to test for either potential contamination during handling procedures in the lab, or potential failure of successful amplification of reference material, due to, for instance, inhibition (see Fig. 5). Finally, the obtained DNA extracts were analysed via ddPCR using the primer/probe assay for the positive internal control in combination with a second primer/probe assay developed for detection of Xenopus laevis DNA. The latter amplifies a 83-bp fragment (primers included) on the 12S region, and those primers amplify 12 (sub)species (Tragulus javanicus, X. tropicalis, X. andrei, X. boumbaensis, X. cf. boumbaensis (BJE2007), X. cf. fraseri (BJE-2004), X. gilli, X. laevis, X. largeni, X. longipes, X. petersii and X. victorianus). It is expected that only X. laevis currently occurs in France (Secondi et al. 2016). ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// doi.org/10.21436/inbor.71707757

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Results Each of the field- and lab-blancs (see Fig. 6, PCR neg. controls) did not show any amplification of X. laevis DNA, whereas all positive reference samples (see Fig. 6, PCR pos. control) showed optimal amplification without any sign of pcr failure or certain levels of inhibition.

Figure 6.

ddPCR output of a positive and negative control sample included at each run, four negative field samples (sample 1 - 4), and two positive samples (sample 34 and 35) taken at the infected pond in La Chapelle-d’Armentières, France.

None of the field samples taken in Flemish or the Walloon part of the study area showed any positive sign of X. laevis DNA, although the positive internal control amplified well and without any sign of inhibition (see figure 6, sample 1 - 4 as an example). Only the two samples taken in the source population (sample 34 and 35, figure 6, samples FRC4W1 and FRC5W1, appendix table 1) at the infected pond in La Chapelle-d’Armentières, showed relatively high eDNA concentrations of X. laevis in both samples taken (on average 7.51 ± 0.85 copies / µL DNA extract).

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References Labadesse, M. & Quevillart, R. (2020). Découverte du Xénope lisse sur la frontière franco-belge et état des lieux des connaissances sur cette espèce en France métropolitaine : répartition et recherche de solutions de gestion. Présentation Journée des observateurs de Raînne, Mons, 26/01/2020. Louppe V, Courant J, Herrel A (2017) Differences in mobility at the range edge of an expanding invasive population of Xenopus laevis in the west of France. Journal of Experimental Biology 220(2): 278-283. https://doi.org/10.1242/jeb.146589 Measey J, Rödder D, Green SL, Kobayashi R, Lillo F, Lobos G, Rebelo R, Thirion JM (2012) Ongoing invasions of the African clawed frog, Xenopus laevis: A global review. Biological Invasions 14(11): 2255-2270. https://doi.org/10.1007/s10530-012-0227-8 Measey J (2016) Overland movement in African clawed frogs (Xenopus laevis): a systematic review. Peerj 4: e2474. https://doi.org/10.7717/peerj.2474 Measey J, Vimercati G, de Villiers FA, Mokhatla M, Davies SJ, Thorp CJ, Rebelo AD, 477 Kumschick S (2016) A global assessment of alien amphibian impacts in a formal framework. 478 Diversity and Distributions 22(9): 970-981. https://doi.org/10.1111/ddi.12462 Scalera, R., Rabitsch, W., Genovesi, P., Adriaens, T., Verzelen, Y., Robertson, P., Chapman, D. & Kettunen, M. (2019). Risk Assessment for African clawed frog Xenopus laevis (Daudin, 1802). In: Roy, H. E., Rabitsch, W. & Scalera, R. (eds.). Development of risk assessments to tackle priority species and enhance prevention : final report: Contract No 07.0202/2018/788519/ETU/ENV.D.2. Luxembourg: Publications Office of the European Union, blz. 1-87 87 blz. doi:10.2779/84029 Secondi J, Dejean T, Valentini A, Audebaud, B, Miaud, C. (2016) Detection of a global aquatic invasive amphibian, Xenopus laevis, using environmental DNA. AmphibiaReptilia 37, 131-136. https://doi.org/10.1163/15685381-00003036. Sousa M, Mauricio A, Rebelo R (2018) The Xenopus laevis invasion in Portugal: An improbable connection of science, mediterranean climate and river neglect. In: Queiroz AI, Pooley S (Eds) Histories of bioinvasions in the Mediterranean. Springer: 133-148.

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Appendix Table 1: Merged table containing samples and metadata for the 2020 campaign and observations of Xenopus laevis in the area. Cluster indicates the pooling of the samples. Name

Type

Cluster

Location

Waterbody

Latitude

Longitude

C1W1

Sample

Flanders

Pond

50,73645142

2,78719246

FC1W2

Sample

Flanders

Pond

50,73651201

2,78857909

FC1W3

Sample

Flanders

Pond

50,73697698

2,79070558

FC1W4

Sample

Flanders

Pond

50,73659756

2,79247679

FC1W5

Sample

Flanders

Pond

50,73826039

2,78757358

FC2W1

Sample

Flanders

Pond

50,7338762

2,78697347

FC2W2

Sample

Flanders

Pond

50,73307131

2,79167945

FC2W3

Sample

Flanders

Pond

50,73510565

2,79111173

FC2W4

Sample

Flanders

Pond

50,73463696

2,78765907

FC3W1

Sample

Flanders

Pond

50,73554127

2,79844268

FC3W2

Sample

Flanders

Pond

50,73789629

2,80723297

FC3W3

Sample

Flanders

Pond

50,73889925

2,8071185

FC3W4

Sample

Flanders

Pond

50,74134904

2,80588204

FC3W5

Sample

Flanders

Ditch

50,7379158

2,80337645

FC4W1

Sample

Flanders

Pond

50,74172535

2,82661563

FC4W2

Sample

Flanders

Pond

50,73891729

2,829243

FC4W3

Sample

Flanders

Pond

50,74115047

2,83110585

FC4W4

Sample

Flanders

Pond

50,74100452

2,82866296

FC5W1

Sample

Flanders

Pond

50,74394251

2,82937622

FC5W2

Sample

Flanders

Pond

50,74315383

2,83311416

FC5W3

Sample

Flanders

Pond

50,74498151

2,83361797

FC5W4

Sample

Flanders

Pond

50,74464639

2,8322309

FC6W1

Sample

Flanders

Pond

50,74334636

2,83761155

FC6W2

Sample

Flanders

Pond

50,7386103

2,84339086

FC7W1

Sample

Flanders

Pond

50,74662725

2,84634389

FC7W2

Sample

Flanders

Pond

50,74413906

2,84823761

FC7W3

Sample

Wallonia

Pond

50,74482408

2,84974479

FC7W4

Sample

Wallonia

Pond

50,7456761

2,85284101

FC8W1

Sample

Wallonia

Ditch

50,73464418

2,84321475

FC8W2

Sample

Flanders

Pond

50,73656194

2,84338307

FC9W1

Sample

Flanders

Pond

50,73772465

2,83004112

FC9W2

Sample

Flanders

Pond

50,73676804

2,83073136

Description eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020

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FC9W3

Sample

Flanders

Pond

50,73557284

2,8313436

FC9W4

Sample

Flanders

Pond

50,73589717

2,83324623

FC10W1

Sample

F10

Flanders

Pond

50,73494684

2,81114197

FC10W2

Sample

F10

Flanders

Pond

50,73434178

2,81094394

FC10W3

Sample

F10

Flanders

Pond

50,7331594

2,81506484

FC11W1

Sample

F11

Flanders

Pond

50,73100527

2,80944487

FC11W2

Sample

F11

Flanders

Pond

50,72974121

2,81010035

FC11W3

Sample

F11

Flanders

Pond

50,72892957

2,80953651

FC11W4

Sample

F11

Flanders

Pond

50,7292242

2,8115783

FC12W1

Sample

F12

Flanders

Pond

50,72834621

2,79913595

FC12W2

Sample

F12

Flanders

Pond

50,72480134

2,79774551

FC12W3

Sample

F12

Flanders

Pond

50,72673513

2,79960961

FC12W4

Sample

F12

Flanders

Pond

50,72527155

2,79969767

FC13W1

Sample

F13

Flanders

Pond

50,72609217

2,80983768

FC13W2

Sample

F13

Flanders

Pond

50,72446753

2,80882638

FC13W3

Sample

F13

Flanders

Pond

50,72523764

2,81225577

FC14W1

Sample

F14

Flanders

Pond

50,7231623

2,81692762

FC14W2

Sample

F14

Flanders

Pond

50,72236437

2,81559138

FC14W3

Sample

F14

Flanders

Pond

50,72004213

2,8190294

FC14W4

Sample

F14

Flanders

Pond

50,72139848

2,81887514

FC15W1

Sample

F15

Flanders

Pond

50,72147877

2,82294502

FC15W2

Sample

F15

Flanders

Ditch

50,71997532

2,82429093

FC15W3

Sample

F15

Flanders

Ditch

50,72361924

2,82917721

FC16W1

Sample

F16

Flanders

Pond

50,72808338

2,83087644

FC16W2

Sample

F16

Flanders

Pond

50,72577489

2,82875659

FC16W3

Sample

F16

Flanders

Pond

50,72687115

2,83456355

FC16W4

Sample

F16

Flanders

Pond

50,72706074

2,83746945

FC17W1

Sample

F17

Flanders

Pond

50,73228495

2,83069437

FC17W2

Sample

F17

Flanders

Pond

50,73129682

2,83121281

FC17W3

Sample

F17

Flanders

Pond

50,7319158

2,83280342

FC18W1

Sample

F18

Flanders

Pond

50,72782217

2,84395363

FC18W2

Sample

F18

Flanders

Pond

50,72667893

2,8454267

FC18W3

Sample

F18

Flanders

Pond

50,72589911

2,84860519

FC19W1

Sample

F19

Flanders

Ditch

50,72323063

2,84036349

FC19W2

Sample

F19

Flanders

Pond

50,72272061

2,84112441

FC19W3

Sample

F19

Flanders

Pond

50,72211344

2,84197396

FC20W1

Sample

F20

Flanders

Pond

50,72058585

2,8532142

eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020 eDNA sample 2020

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// doi.org/10.21436/inbor.71707757

Page 15 of 17

FC20W2

Sample

F20

Flanders

Pond

50,71934923

2,85362635

FC20W3

Sample

F20

Flanders

Ditch

50,71810488

2,85195348

FC20W4

Sample

F20

Flanders

Pond

50,719092

2,853748

FC21W1

Sample

F21

Flanders

Ditch

50,71301886

2,86961024

FC22W1

Sample

F22

Flanders

Ditch

50,70832108

2,86321682

FC23W1

Sample

F23

Flanders

Pond

50,71237271

2,85955669

FC23W2

Sample

F23

Flanders

Ditch

50,713309

2,858538

WC1W1

Sample

Wallonia

Ditch

50,73659014

2,85123576

WC1W2

Sample

Wallonia

Pond

50,73547616

2,85071247

WC1W3

Sample

Wallonia

Ditch

50,73507758

2,84855499

WC1W4

Sample

Wallonia

Pond

50,73484501

2,85031908

WC1W5

Sample

Wallonia

Pond

50,73556684

2,855811

WC1W6

Sample

Wallonia

Pond

50,73581391

2,85291998

WC2W1

Sample

Flanders

Pond

50,73097417

2,84510673

WC2W2

Sample

Wallonia

Ditch

50,72950197

2,84777957

WC2W3

Sample

Wallonia

Pond

50,73211524

2,85098553

WC2W4

Sample

Wallonia

Pond

50,731172

2,847548

WC3W1

Sample

Wallonia

Ditch

50,72664158

2,86310478

WC3W2

Sample

Wallonia

Ditch

50,72437055

2,8528524

WC3W3

Sample

Wallonia

Ditch

50,72067519

2,86259816

WC3W4

Sample

Wallonia

Pond

50,725811

2,859583

WC3W5

Sample

Wallonia

Ditch

50,72097802

2,86936162

WC4W1

Sample

Wallonia

River

50,703989

2,874443

WC5W1

Sample

Wallonia

Ditch

50,713068

2,890848

WC5W2

Sample

Wallonia

Pond

50,712467

2,892805

WC5W3

Sample

Wallonia

Ditch

50,711336

2,892272

WC5W4

Sample

Wallonia

Ditch

50,709509

2,893378

WC6W1

Sample

Wallonia

River

50,698368

2,90749

FRC1W1

Sample

FR1

France

Ditch

50,712591

2,854114

FRC2W1

Sample

FR2

France

Ditch

50,704234

2,856457

FRC2W2

Sample

FR2

France

Pond

50,704303

2,857162

FRC2W3

Sample

FR2

France

Pond

50,70466

2,858465

FRC3W1

Sample

FR3

France

Pond

50,702273

2,889605

FRC3W2

Sample

FR3

France

Pond

50,701576

2,889443

FRC3W3

Sample

FR3

France

Pond

50,701746

2,89097

FRC4W1

Sample

FR4

France

Pond

50,670734

2,906984

FRC5W1

Sample

FR5

France

Pond

50,670178

2,906932

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Page 16 of 17

doi.org/10.21436/inbor.71707757

ObsB2006

Observation

Wallonia

Pond

50,70841291

2,87868765

ObsB2016

Observation

Wallonia

River

50,69896398

2,90776707

ObsF2018

Population

France

Pond

50,67045

2,906893

ObsF2019

Observation

France

Unknown

50,66929585

2,94707687

Observation Wallonia 2006 Observation Wallonia 2016 Known since 2018 Observation France 2019

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Page 17 of 17