When amphibians become a problem – a balance of the first four years of the control and eradication plan of the African clawed frog on the streams of Oeiras Municipality

(by Rui Rebelo)

As a result of introductions out of its native range, the African clawed frog, Xenopus laevis, is one of most widely distributed amphibians in the world. It was introduced in four continents, with considerable success in temperate and Mediterranean-climate regions, where its direct and indirect impacts changed the ecology and dynamics of invaded ecosystems. This species may also be an asymptomatic vector for pathogens (namely the fungus Batrachochytrium dendrobatidis), that may thus be transmitted to native amphibians.

Reproducing populations of this species were found for the first time in Portugal in the Laje stream (in 2006) and in Barcarena stream (in 2008). Both streams run through Oeiras Municipality. A control and eradication plan is taking place since 2010, under a protocol signed by the Institute for the Conservation of Nature and Forests, I.P., the Oeiras Municipality, the Centre for Environmental Biology/ FCUL, and the Instituto Gulbenkian de Ciência.

In this talk, I will present the main results of the plan thus far. At the end of the fourth year of the plan, the state of the X. laevis populations in both streams is contrasting. At Laje, the species was very abundant at the start of the plan, and in 2013 we only captured 7 adults, with no signs of reproduction in all the stream. On the contrary, at Barcarena the species reproduced in at least two stream stretches, its main nucleus occupies a relatively large stretch of the stream, and 845 individuals (the large majority of them 1-year old juveniles) were captured in 2013. The capture of 1-year olds means that probably a single successful year (2012) could rapidly repopulate a significant portion of the stream. Taking into account its invasive potential, the risk of colonization of other areas, and the success of the plan at Laje thus far, the plan will continue in the next years, and new methodologies will be tested.

Congress Collaborators

  • Sara Costa
  • Emanuele Fasola
  • Ariana Moutinho
  • Iolanda Rocha
  • Inês Bulhosa
  • Bárbara Santos
  • Isabel Damas
  • Cátia Venâncio
  • Nuno Costa
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