Abstract
Mountain karst ponds are sensitive environments, hosting complex trophic networks where amphibians play a major role, often as top predators. The diet of the Italian crested newt (Triturus carnifex) is still poorly known for populations occupying mountain karst ponds. These are traditionally used as livestock’s watering points, leading to water pollution due to excreta and wading behavior. The aim of this paper is to understand the relationship between T. carnifex diet composition, assessed through the stomach flushing technique, and physical and chemical characteristics in mountain ponds, focusing on parameters altered by livestock pressure, such as ammonium concentration and dissolved oxygen. The high diversity of prey items found within the newts’ gut contents confirms the generalist diet even in mountain ponds. The number of prey taxa, their relative abundance and Shannon–Wiener diversity index show variations among the sampled sites, related to livestock organic pollution. Moreover, we report the very first European records of microplastic items in amphibians’ stomach content, which also represent the first evidence for Caudata worldwide. Our findings suggest that livestock pressure directly influences T. carnifex diet and highlight that the emerging issue of plastics is a threat even in remote high-altitude environments.
Highlights
High-altitude ecosystems are nowadays more and more studied because of their susceptibility to ongoing climate change and habitat loss [1,2,3]
Together with prey items and other materials, we unexpectedly found microplastics in some stomach contents
The stomach contents of 239 Italian crested newts were collected from the nine sampling sites
Summary
High-altitude ecosystems are nowadays more and more studied because of their susceptibility to ongoing climate change and habitat loss [1,2,3]. Many species have been proven to shift their ranges to higher altitudes [4,5,6] or, when the habitat does not permit these migrations, to possibly go extinct [7,8,9]. Karst mountain ponds are sensitive water bodies because of their exposure to several highly variable environmental factors. They are subject to seasonal snow coverage, noticeable daily and annual thermal excursion, UV-radiation and water-level changes [10,11,12,13]. The species belonging to these animal communities are often of conservation concern, because of their specialization to mountain environments and to low connectivity among ponds [10,17]
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