From a local observation to a European-wide phenomenon: Amphibian deformities at Serra da Estrela Natural Park, Portugal

Abstract

In the last decades increasing records of morphological abnormalities in many amphibian populations have become subject of scientific interest. Once considered a mere curiosity, this worldwide phenomenon has been highlighted as a potential local conservation issue, for it appears to be yet another threat to amphibian diversity. Our study reports the first cases of amphibian deformities for North-Central Portugal, which are put in context with a review comprising European records since the 18th century. Amphibian populations (Lissotriton boscai, Triturus marmoratus and Pelophylax perezi) were sampled for four sampling years at Serra da Estrela Natural Park. With approximately 1400 post-metamorphic individuals examined, we found 12 cases of deformity including anophtalmy, brachydactyly, ectrodactyly, ectomely, polydactyly and polyphalangy. Deformity prevalence varied between years and species, rarely exceeding 2%. Our results are in accordance with European trends, since the majority of the recorded cases were found in limbs of urodeles. The presence of deformities in three different species points toward environmental causes, with predation as the most parsimonious explanation. Although not alarming, we reinforce the need for continuous monitoring of amphibian communities, from an interdisciplinary perspective, since even protected and pristine areas are not immune to new emerging threats that can act in synergy.