Descripció morfològica i anàlisi de la connectivitat del nucli poblacional de tortuga d’estany (Emys orbicularis) al PEIN Estanys de Sils

Abstract

The European pond turtle (Emys orbicularis) and the Mediterranean pond turtle (Mauremys leprosa) are the two native species of the Iberian Peninsula. The first one has seen an important decline at peninsula scale, mainly due to habitat loss. During the last years, there have been some projects to improve the state of his populations in Girona region. In spite of that, the specie has not been able to recover to the impacts that it has been suffering since the fifty’s decade, with the drying of water bodies to convert them into crops and industrial parks. In this study, it has been evaluated the nucleus of E. orbicularis in Estany de Sils, a protected zone that is part of PEIN and N2000 network. In addition, it has been defined the quality of it as a habitat, and it has been evaluated, trough the database of Fundació Emys, the dispersal happening during the last years with the main goal of identifying the role that the Estany de Sils can play in the connectivity with the nuclei previously studied by Fundació Emys. The result of the analysis of the population has shown a population size of 285 individuals. The sex ratio was divided in: 65% males, 25% of them, 6% juveniles, 2% neonates and finally the 2% of individuals of whom the sex could not be defined. The habitat characterization has shown a low quality area, in conservation and forest river terms, with presence of exotic species (animal and plant) and, in some cases, with wastes. In terms of dispersal and reproduction, it has been confirmed the presence of two newborns and two dispersal routes, with four happenings in a ten-year period. These numbers explain the connectivity between the Estany de Sils and the Riera de Caldes de Malavella by one hand and show evidence of reproduction by the other. Finally, the habitat analyze with GIS software has drawn a really wide scenario, with forests, open spaces, irrigation channels and streams that could carry out the function of corridor to a big amount of species. Instead of that, the barrier effect due to the traffic infrastructures could have caused the low number of dispersal events observed