Standard Talk (15 mins) Australian Society for Fish Biology Conference 2022

Detecting the Invasive Jaguar Cichlid in the Pioneer River using a Non-invasive Environmental DNA Approach (#52)

Michael Mottley 1 , David Hurwood 1 , Bonnie Holmes 2
  1. School of Biology & Environmental Science, Queensland University of Technology, Brisbane
  2. School of Science, Technology and Engineering, University of the Sunshine Coast, Sunshine Coast

Invasive species are a key concern for managers of freshwater ecosystems across Australia. Traditional detection approaches however, have a number of practical limitations, particularly in aquatic environments. Environmental DNA (eDNA) has emerged as a sensitive and non-invasive detection tool which enables potential early detection and effective monitoring. This method uses DNA that organisms naturally shed into their environment to target and detect specific taxa, or communities. This study addressed issues surrounding the flow management of the Pioneer River in Mackay, Queensland, which recently had an establishment of the invasive jaguar cichlid (Parachromis managuensis), a piscivorous fish species native to South America. The detection of this potential environmental menace led to closures of several fishways across the catchment, preventing the natural dispersal of both invasive and native fish species alike. The aims of this study were to develop detection protocols for P. managuensis in the region using an eDNA approach, use this to determine the species distribution across the catchment and finally, to provide this information to stakeholders so that management actions could be taken based on eDNA outcomes. Samples from 41 sites were collected then processed using a species-specific qPCR approach, with primers and probe sequences developed specifically to target P. managuensis. The assay had a 98% chance of detection given the species was in fact present. P. managuensis had spread well beyond managers' predictions, with the species present upstream of both the Dumbleton and Marian Weirs, as well as having spread to some adjacent tributaries. This study highlighted a number of implications for the management of P. managuensis and other invasive fish species in Queensland, having shown eDNA’s effectiveness and applicability as a detection and monitoring tool in Queensland waters. eDNA methodologies represent a powerful monitoring tool which managers and policy should endeavour to incorporate into standard practice.