Passive eDNA Sampling as a Promising Tool for Standardizing Wetland Biodiversity Assessments

Environmental DNA (eDNA) metabarcoding is a widely used approach for biodiversity assessments across ecosystems. In aquatic environments, eDNA is typically collected via active water filtration, which requires specialized equipment and is challenging in turbid waters. This study evaluates the efficiency of an alternative method for lentic (standing) freshwaters based on passive eDNA sampling by submersing low‐cost DNA traps equipped with three collection materials (cellulose nitrate, glass fiber, and coffee filters) in a freshwater pond. We directly compared the results with active filtration performed at the same time and locations. Freshwater communities were identified with a multiplex PCR approach targeting macrophytes, macroinvertebrates, and vertebrates. Results showed that passive sampling was overall comparable to active filtration for detecting macrophyte species, with no significant differences in ASV counts, species richness, or Shannon diversity. For vertebrates, passive sampling recovered similar species richness and ASV counts, although active filtration yielded higher Shannon diversity. For macroinvertebrates, active filtration recovered significantly higher species richness and Shannon diversity than passive sampling in this study system, while overall macroinvertebrate recovery in both methods was likely constrained by marker choice and sampling effort. Furthermore, no significant differences in eDNA capture efficiency were found among the tested collection materials, including the low‐cost paper from coffee filters. We conclude that, due to the ease of field deployment coupled with merging of multiple low‐cost field replicates in the lab, passive sampling with DNA traps offers scalability and flexibility, thereby providing a cost‐ and time‐efficient alternative to active filtration for extensive freshwater biodiversity monitoring.