Detection of environmental DNA from amphibians in Northern Europe applied in citizen science

Abstract

Many species of amphibians in Northern Europe are threatened and the local distributions are rarely described in detail. Application of modern molecular methods provides an important supplementary tool for monitoring the distribution and diversity of amphibians. For this purpose, we designed, tested, validated, and optimized 14 species‐specific assays on genomic DNA extracted from tissue samples to use for quantitative polymerase chain reaction (qPCR) setups targeting mitochondrial DNA from amphibians in freshwater samples. The tests confirmed species specificity for all assays. Considering a systematic definition of the limit of detection for each of the assays, the presented qPCR assays are unlikely to return false positive detection from any co‐occurring species in northern Europe. For field validation, the qPCR assays were applied in a large‐scale nationwide citizen science project in which sampling and qPCR analysis was carried out by high school students. Data from the citizen science project returned the expected results when compared to the known regional distribution of the target species and confirmed the presence of nine out of 14 Danish species of amphibians in the collected freshwater samples. Four out of 2550 qPCR test sets carried out by the high school students required a professional reanalysis in multiple replicates due to initial unexpected results. This emphasizes that efforts from citizen science may generate large amounts of valuable data, as long as the results are carefully scrutinized by experts.

Emerging technologies in citizen science and potential for insect monitoring

“…This may prove especially important due to recent increased focus on ethical insect monitoring and the shifting public opinion of insects [ 80 ]). Importantly, it has been shown that citizen scientists with minimal training are effective in eDNA sampling [ 72 ], thus opening participation to people who have previously been under-served, and participants can even be involved in the corresponding laboratory analyses [ 81 , 82 ]. Furthermore, such participation can enhance citizen scientists' understanding of biodiversity, ecosystems, and the principles of eDNA [ 73 , 83 ].…”

Exploring the potential of extreme citizen science with Danish high school students using environmental DNA for marine monitoring

“…Several research groups have found great success in inviting school students to participate in citizen science projects with examples of primary and secondary schools collecting insects via Malaise traps (Steinke et al, 2017), testing the ability of schoolchildren to accurately estimate the strength of biotic interactions (Castagneyrol et al, 2020), letting high school students identify archaeological leather fragments with protein analysis (Brandt et al, 2022) or when high school students conduct eDNA analysis in order to detect distribution of amphibians (Knudsen et al, 2023). The schools represent a vast number of participants, students feel engaged in the work and have a positive scientific learning outcome when the teachers are able to combine the citizen science labor with school curriculum.…”

“…Engaging and training citizen scientists in advanced laboratory analysis, such as the monitoring of environmental DNA (eDNA) in water samples, has promising applications for large-scale national eDNA surveillance of aquatic species that can be used in governmental mapping and conservation efforts (Tøttrup et al, 2021;Knudsen et al, 2023). In this paper we will showcase the development of an existing citizen science project with focus on eDNA monitoring towards a more comprehensive method for engaging volunteers in field sampling and laboratory analysis.…”

“…Several research teams have developed eDNA analysis protocols, which have yielded a range of methods for detecting the genetic material of aquatic organisms of a variety of different taxonomic groups and in different environments (Goldberg et al, 2016;Tsuji et al, 2019). The easy accessibility of eDNA methods have facilitated their use in citizen science programs where samples of water have been collected and analyzed (Tøttrup et al, 2021;Agersnap et al, 2022;Knudsen et al, 2023).…”

“…These false detections typically arise from sample contamination with unrelated DNA or sample mix-ups, occurring possibly both in the field and laboratory settings. To address challenges in eDNA monitoring within a citizen science framework, it is vital to systematically address the potential for false positive and false negative detections (Goldberg et al, 2016;Agersnap et al, 2022;Knudsen et al, 2023).…”