Detecting cryptic terrestrial species in targeted eDNA sampling

Mr Ryan Ellis¹, Dr Nihara Gunawardene¹, Mr Chris Knuckey¹, Dr Joel Huey¹, Dr Kat Dawkins², Dr Rose Lines², Dr Shane Herbert²

¹Biologic Environmental Survey, ²Curtin University

Abstract:

The Pilbara olive python is a large cryptic species endemic to Western Australia’s Pilbara and Gascoyne bioregions. The species is most often encountered in the vicinity of permanent or semi-permanent waterbodies in rocky ranges or among riverine habitats. Due to the species’ Vulnerable  conservation status (State and Commonwealth), environmental impact assessments within the species range require surveys be conducted to establish the species’ presence. As a cryptic species, it is often challenging to establish presence or absence in isolated water holes. A study was conducted to investigate whether eDNA is a useful tool to complement traditional survey methods.

Five, 1L water samples were taken from seven water features across a large study area in the eastern Pilbara region. Each water feature was visited up to three times during three separate sampling events between August and November 2020. These water samples were filtered in situ, frozen and returned to Perth for processing. The filter papers were processed using eDNA metabarcode sequencing and a tailored 16S reptile assay. From these seven water features, five yielded positive detections. Of these five, the python was also observed during traditional sampling methods at four of the sites. There were no pools where the python was observed and the eDNA results were negative (false negative). This case study presents an example of where eDNA samples can supplement traditional survey methods and provide additional data for greater interpretive power for understanding distribution of cryptic species in remote landscapes.

Biography:

Biography to come