A Comparison between Passive airDNA Collection and Extraction Methods on the Recovered Terrestrial Vertebrate Assemblage.

Over the past half-decade, the collection of airborne environmental DNA (airDNA) has emerged as a novel tool for the biomonitoring of terrestrial vertebrates. Similar to other eDNA collection substrates (e.g., soil and water), the filtering of airDNA, while promising, requires rigorous methodological testing before widespread implementation. Two aspects of eDNA filtration that influence the recovered species assemblage are collection and extraction methods. Here, we assess the comparative performance of three collection matrices: cloth filters, paraffin gauze and PCR plate seals, alongside four readily available extraction kits: Qiagen DNeasy Blood & Tissue, Qiagen DNeasy PowerSoil Pro, MagMAX Total Nucleic Isolation and Quick-DNA Miniprep Plus extraction kits. We deployed these passive airDNA filters in a riparian urban parkland within the Tarradarrapin Creek Wetlands in south-east Queensland, Australia. Through the use of both a universal mammalian and universal vertebrate primer, we demonstrate the combination of cloth filters and the Blood & Tissue extraction kit records both the highest number of overall and informative terrestrial operational taxonomic units (OTUs) as well as a diverse and non-variable species assemblage between replicates. Here, we show that optimising airDNA methodologies, and particularly using cloth filters with the Blood and Tissue extraction kit, allowed us to enhance the performance of this novel biomonitoring technique, a crucial step toward supporting its uptake alongside traditional monitoring methods (e.g., camera traps, bioacoustics or aquatic eDNA).