Active or passive? A multi-marker approach to compare active and passive eDNA sampling in riverine environments

Area of Science:

• Environmental DNA (eDNA) analysis
• Biodiversity monitoring
• Aquatic ecosystem assessment

Background:

• Environmental DNA (eDNA) is a powerful tool for biodiversity monitoring.
• Aquatic eDNA collection methods are broadly categorized into active (e.g., filtration) and passive sampling techniques.
• Passive eDNA Sampling (PEDS) is a newer method utilizing adsorbent materials.

Purpose of the Study:

• To compare the performance of water filtration and Passive eDNA Sampling (PEDS) using granular active carbon.
• To evaluate detected taxa and community composition differences between the two sampling methods.
• To assess cost-effectiveness and environmental sustainability of each method.

Main Methods:

• Collected eDNA samples from four river sites using both water filtration and PEDS.
• Amplified eDNA using three molecular markers (18S rRNA, 12S rRNA, COI) targeting invertebrates and vertebrates.
• Analyzed and compared the taxonomic diversity and read variances between methods.

Main Results:

• PEDS detected more species on average for 18S rRNA and 12S rRNA markers, with higher homogeneity in 18S rRNA results.
• PEDS captured more microinvertebrates and chironomids, while filters yielded more ephemeropterans, trichopterans, and acarines.
• Both methods performed well for amphibians; PEDS showed lower fish detection rates, while filters performed similarly for vertebrates overall.

Conclusions:

• Neither water filtration nor PEDS is universally superior for eDNA sampling; method choice depends on research goals.
• PEDS offers advantages in cost-effectiveness and environmental sustainability.
• Future research should focus on comparing novel eDNA sampling methods across broad taxonomic groups.