Environmental variables that influence platypus (Ornithorhynchus anatinus) eDNA detection: an insight into eDNA study design for platypus occupation

Surveying platypus, Ornithorhynchus anatinus, occupancy patterns presents significant challenges because of their elusive nature and the often-inaccessible environments they inhabit. Traditional methods, such as observer sightings and mark–recapture, are labour-intensive and limited in spatio-temporal coverage. Recent advances in environmental DNA (eDNA) technology offer a promising alternative, allowing for broader and less invasive detection of aquatic species. This study investigates the use of eDNA for detecting platypuses across various environmental conditions in Kosciuszko National Park, New South Wales (NSW), focusing on how abiotic factors such as altitude, stream order, and seasonal variations may influence detection probabilities. Sampling occurred over four seasons from November 2021 to May 2023 at 46 sites, including high-altitude and remote locations. Results indicated that eDNA successfully detected platypuses in previously undocumented high-altitude sites of NSW and showed significant influences of stream order, altitude and seasonality on detection rates. This research highlighted the potential of eDNA to improve platypus distribution knowledge and emphasises the importance of considering environmental factors in monitoring. Future studies should refine eDNA protocols to enhance reliability across diverse habitats.