Using Environmental DNA to Characterize Amphibian Communities at Sites Infected with Batrachochytrium salamandrivorans in the Netherlands

Abstract

Batrachochytrium salamandrivorans (Bsal) fungus has the potential to cause high mortality rates in some European salamanders and newts (urodelans) and is in the process of expanding its invasive range in Europe. Therefore, monitoring its distribution and better understanding both the species threatened and the mechanics of infection are essential in mitigating damage Bsal may cause. Environmental DNA has emerged as a promising noninvasive method for detecting both this fungal pathogen and amphibian communities in infected areas. We applied these methods in the province of Gelderland, Netherlands, where the pathogen has previously been detected and is expanding its range, with the goal of characterizing the natural amphibian community present. We sampled 27 bodies of water in the region surrounding the known outbreak sites, determined the presence or absence of Bsal using a targeted quantitative polymerase chain reaction assay, and applied an environmental DNA metabarcoding approach to characterize the amphibian communities using two different primer sets. The 12S vertebrate primer set outperformed the 16S amphibian primer set and detected all expected amphibians in the study area: Bufo bufo, Lissotriton vulgaris, Pelobates fuscus, Pelophylax spp., Rana temporaria and Triturus cristatus. Bsal was detected at 8 of 27 ponds. A distance-based redundancy analysis found a weak but significant relationship between Bsal presence and composition of amphibian communities. This study may provide a basis for future studies on Bsal and its relationship with amphibian communities in Europe, highlighting the need for further research into mechanisms of persistence and transmission between bodies of water.