Dr Erin Hahn1, Dr Rachel Tulloch1, Daphne Willemsen2, Dr James Bickerstaff1, Dr Lisa Schwanz2
1CSIRO, National Research Collections Australia, Canberra, Australia, 2Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, Australia
Biography:
Dr Erin Hahn is a Research Scientist at CSIRO’s Australian National Wildlife Collection, where she leads research developing reliable and scalable approaches for airborne eDNA biodiversity monitoring. Her broader research uses genomic and epigenomic approaches to investigate biodiversity through space and time, including pioneering methods to recover genomic and regulatory information from century-old formalin-preserved museum specimens. Erin completed her PhD at the University of Arizona, where she studied temporal population genetics and epigenetics in endangered Sonoran pronghorn. She is a passionate science communicator, a Science & Technology Australia Superstar of STEM alumnus, and Co-Vice President of the Southern eDNA Society.
Abstract:
Airborne eDNA can recover diverse terrestrial taxa, but interpreting detections requires understanding how biodiversity signals vary across space and time. We examined fine-scale spatial and temporal variation in airborne eDNA detections using two sampling studies in southeastern Australia. At the Royal Botanic Gardens Sydney (RBG), we deployed paired samplers at trunk and canopy height on five trees containing natural wildlife hollows to characterise fine-scale spatial variation in biodiversity recovery around these important microhabitats. At the CSIRO Black Mountain campus in Canberra, adjacent to native bushland, we conducted repeated sampling over one year to characterise temporal turnover and seasonal patterns. At RBG, trunk and canopy samplers around the same hollow-bearing trees recovered similar taxon richness but compositionally distinct assemblages. Paired samples from the same tree shared only 22% of their combined detected taxa, with only modest evidence that samples from the same tree were more similar than those from different trees. At Black Mountain, temporal turnover was similarly pronounced. Consecutive sampling periods shared a median of 18% of plant taxa and 11% of metazoan taxa, while 46% of plant and 66% of metazoan taxa were detected on only one sampling date. Plant richness also varied seasonally, peaking in spring with a median of 26 taxa per sampling date compared with 8 in winter. Together, these results show that individual airborne eDNA samples capture distinct snapshots of a spatially and temporally dynamic biodiversity signal. Accounting for this heterogeneity will be important when designing sampling strategies and interpreting non-detections in terrestrial biodiversity monitoring.