Applying eDNA Methods to Monitor the Distribution of Remnant and Translocated Populations of an Endangered Amphibian, Litoria booroolongensis

Effective conservation of threatened species relies on precise detection methods to inform conservation management strategies. Here, we developed a new environmental DNA (eDNA) assay to detect the endangered Booroolong frog (Litoria booroolongensis) in river water samples throughout their range in Australia. The suitability of the assay to detect Booroolong frog eDNA was first validated ex situ from a population of captive-bred frogs at Taronga Zoo, New South Wales. We then established the detectability of Booroolong frog DNA from river water samples collected in situ. The new assay successfully detected Booroolong frog eDNA in water samples collected from the breeding enclosure, from water samples exposed to adult frogs and frog egg masses. Testing in the field confirmed the effectiveness of the assay at detecting Booroolong frog eDNA in environmental water samples collected in situ from sites with known presence of the species determined from prior nocturnal surveys. Our results demonstrate the efficacy of eDNA for detecting Booroolong frogs from river water samples across its geographic range. Ongoing monitoring utilizing eDNA has the potential to support conservation efforts by enabling more efficient and widespread surveys for this endangered species.