Invasive Xenopus in Oeiras (near Lisbon, Portugal)

The invasive population of African clawed frogs in Portugal are also believed to have originated from a laboratory stock (Measey et al. 2012). Over the last 15 years, Rui Rebelo has been working hard to eradicate these animals from two streams invaded in the suburb of Oeiras, east of Lisbon where he works at the university. Their presence was first reported in a newspaper article in 2007, and an eradication programme has been ongoing since 2010. They have almost removed all of the animals, but a few still remain in the streams and more in a golf course between them.

In a very short trip to Lisbon, I joined Rui, the fantastically enthusiastic Monica Sousa (DCNB/DCM - Divisão de Conservação e Monitorização), and two technicians employed to electrofish the streams to remove all animals over the next couple of years: Manuel Sampaio & Bernardo.

In only a day, we visited first the golf course to sample animals waking up from the mud to find that they were being stunned by Manuel's volts (they quickly return to normal once they get into a bucket of water), and then to each of the streams where we managed to catch just two more individuals hiding in the stonework at the bottom of the walls.

It was a fabulous visit and really very successful, adding another invasive population to the growing list of sites in our study on the genomics of Xenopus laevis.

Many thanks go to Monica and Rui for making this day possible and for their ongoing work on removing this invasive population from Portugal. I'm sure that you'll manage it!

Visiting the lab in Paris

Taking advantage of the trip to Western France, it was only a short hop on the train to go to Paris where I met up with MeaseyLab PhD student, Laurie Araspin. Keen readers of the blog will know that Laurie is a co-tutelle student who is also registered with Anthony Herrel at the MNHN in Paris. Laurie was in South Africa collecting animals for her study and you can read all about that trip here.

We made arrangements to catch up with Laurie in her office in Rue Buffon in the 5eme arrondissement in Paris.

Laurie showed us the animals that had been collected in South Africa, and we also had a chance to meet Pedro Padilla - another well published Xenopus researcher who now works on invasive Pelophylax frogs.

Also present in Paris was Sara Zakrzewski who is using the Xenopus collected on these trips, plus others sourced from invasive populations around the world, to compare investment into different organs in various populations. 

Sara, John, Laurie and Dareen - the Xenopus crew in Paris!

It was an awesome couple of days in the baking hot French capital - thanks for making it so enjoyable!

Back at the Xenopus invasion in Western France

In 2003, I visited Antonie Fouquet in the French département of Deux-Sèvres as Antoine had been working on an invasive population that had emerged near his parents' home. He had conducted a massive effort each summer during the holidays, mapping the presence and absence of ponds in the area (later leading to a publication: Fouquet & Measey 2006). Although Antoine is no longer involved in the research of Xenopus from this area, a huge debt of gratitude goes out to him for this unpaid research he conducted as an undergraduate student.  

As part of the genetic study of native and invasive populations (see blog posts here and here), Dareen Amojil and I visited the invaded region in June 2022, immediately after our visit to Sicily (see here). 

The two regions looked very different and it was immediately obvious how different the habitats are that are occupied in Western France compared to those we had sampled in South Africa (see blog posts here and here and here), and Sicily (see here). Helped by Jean Secondi (who some of you will remember having co-supervised Natasha Kruger - and visiting South Africa), we set out to a number of ponds in the core of the range (around the hamlet of Bouille-St-Paul - where it all started), and at the periphery - now some 50 km from the core. 

The most abundant sites that we visited were two sewerage works, one of which was where Julien Courant and Natasha Kruger had conducted experiments for their doctoral studies. Happily, we managed to catch animals from throughout this large invasive range. Extensive thanks go to Jean Secondi and Axel Martin from the Thouars Community.

Further Reading:

Fouquet, A., & Measey, G.J. 2006. Plotting the course of an African clawed frog invasion in Western France. Animal Biology 56, 95-102. https://doi.org/10.1163/157075606775904722 

Grosselet O., Thirion J.M., Grillet P. et Fouquet A., 2005 – Etude sur les invasions biologiques : cas du Xénope commun ou Xénope du Cap, Xenopus laevis (Daudin, 1802). Conseil Général des Deux-Sèvres (Niort) et Agence de l’Eau Loire-Bretagne (Poitiers), 58p.

Visiting the population of African clawed frogs in Sicily - at last!

Of all the invasions ofX. laevisaround the world, the population in Sicily has been one of the easiest to visit, yet received surprisingly little attention. Of course, Francisco Lillo conducted many excellent studies under the supervision of Mario Lo Volvo during his PhD in the early 2000’s. But since then, this population has been spreading into the beautiful Sicilian countryside. 

Keen readers of this blog will know that I have been working on caecilians for many years, but this was my first visit to Sicily, and it was especially pleasing to work alongside some excellent local herpetologists, one of whom has taken up studies of this invasion: Simone Costa - again under the supervision of Mario.

Lillo et al. (2005) first reported the discovery of an established population from June 2004 when individuals were observed in the drainage of the Fiume Iato near Lago Poma in northwestern Sicily. Apart from 2 individuals captured in 1999, this was the first time that the species had been observed on the island. The source of this invasion is thought to be from laboratories at the University of Palermo whereX. laeviswas used for studies on developmental biology (Measey et al 2012). 

With the generous help of Mario Lo Volvo, Simone Costa and his band of herpetologist helpers (Mathia, Bruno & Peppe) we dashed around the countryside in search of points on Simone’s red list of occupied ponds with dense populations. 

One of the surprises Dareen Amojil and I was the amount of native herpetofauna that was also attracted to our traps. Most prominent wereNatrix helvetica, the Italian Barred Grass Snake - which were particularly good natured about having spent a night in traps with one of their favourite foods (lumps of Xenopus could be seen along their body and Simone informed us that individuals would occasionally vomit up their recently acquired prey). In addition, traps often containedEmys orbicularis, the European Pond Turtle, and when present it was often the case that they had shredded some of the X. laevis  also in the traps. One trap (pictured above) was so heavy with these additional occupants that I struggled to lift it out of the pond.

We had such a great time sampling in Sicily that we have to make a special thank you to Simone, Mathia, Bruno, Peppe and (of course) Mario. Thanks so much for all your help and friendship. We look forward to returning to Sicily soon.

Further reading:

Lillo, F., Marrone, F., Sicilia, A., Castelli, G. and Zava, B., 2005. An invasive population of Xenopus laevis (Daudin, 1802) in Italy. HERPETOZOA 18 (1/2): 63-64.

Measey, G.J., Rödder, D., Green, S.L., Kobayashi, R., Lillo, F., Lobos, G., Rebelo, R. and Thirion, J.M., 2012. Ongoing invasions of the African clawed frog, Xenopus laevis: a global review.Biological Invasions,14(11), pp.2255-2270.