The Herpetological Journal

pp. 197-204
Authors: Cruz, M.J.; Segurado, P.; Sousa, M. & Rebelo, R.

Abstract: Amphibian populations have suffered declines throughout the world due to factors such as habitat destruction, climate change, chemical pollution or the introduction of exotic species. The correct assessment of the declines, as well as of their causes, is dependent on sound monitoring protocols in selected areas, but medium and long-term studies including data before the declines are extremely rare. The red swamp crayfish, Procambarus clarkii, recently introduced to the Iberian Peninsula, is an efficient predator of amphibian embryos and larvae and recent reports have shown that its presence in a water body is a negative predictor of the presence of amphibian breeding populations. Here we compare data from a survey of the amphibian community of the Paul do Boquilobo Nature Reserve, central Portugal, made in 2001, with data gathered in 1992/93, just after P. clarkii arrived in the reserve. The first survey confirmed the presence of 13 species of amphibians in the reserve, four of them very abundant. In 2001, only six amphibian species were recorded, all in extremely small numbers. In only eight years, most of the previously abundant species strongly declined (e.g. Pleurodeles waltl, Triturus marmoratus and Rana perezi) or went locally extinct (e.g. Hyla arborea and Pelodytes punctatus). However, several species that disappeared from the main water body of the reserve continued to reproduce in nearby ponds without crayfish. Crayfish introduction seems the most probable cause for these declines. Therefore, the survival of several Iberian Peninsula amphibian populations may be dependent upon the correct management of the habitats not easily reached by the crayfish.

Keywords: AMPHIBIAN DECLINE, LONG-TERM MONITORING, WETLAND, INVASIVE SPECIES