Dr Petra Quezada- Rodriguez1, Dr Tansyn Noble1, Dr Anusuya Willis2, Dr Richard Taylor2, Dr Yen Truong3, Ms Jenn Soroka4, Dr Alejandro Trujillo-Gonzalez4, Dr James Wynne2
1CSIRO, Darwin, Australia, 2CSIRO, Hobart, Australia, 3CSIRO, Clayton, Australia, 4University of Canberra, Canberra, Australia
Biography:
Petra Quezada is a veterinarian with a strong background in aquatic animal health across a range of aquaculture species. She has a combined experience of 11 years in research and commercial farm consultancy for prawn, fish and shellfish production. Her interest in aquatic animal health includes biosecurity, disease monitoring and health-promoting strategies. She is currently a Postdoctoral fellow at CSIRO Darwin, working on prawn pathogen monitoring using eDNA and rapid tests.
Abstract:
Heterosigma akashiwo (H. akashiwo) continues to cause losses and animal mortalities in Australian aquaculture farms. Currently, the detection of H. akashiwo relies on microscopy and visual identification/quantification of live cells by specialised personnel. The suitability of these methods to detect H. akashiwo early in a blooming event at the farms has been questioned because both are labour intensive, need specialised staff and the limit of detection depends on visual identification. We developed a molecular assay based on qPCR for the quantification of H. akashiwo from prawn ponds using environmental DNA samples. A species-specific qPCR assay that targeted H. akashiwo was developed in collaboration with the National eDNA Reference Centre, University of Canberra. The qPCR assay was subsequently validated in a series of lab-based experiments using pure H. akashiwo cultures from the Australian National Algae Culture Collection at CSIRO. Limit of detection and assay efficiency were determined using several DNA collection methods as well as use in a portable qPCR machine (biomeme). The test exhibited a limit of detection of 10 cells/ mL (100% detection rate) when cells are concentrated through centrifugation (cell pellet), active filtration or passively on submerged filter membranes. Additionally, different eDNA collection methods and materials were compared using samples from tropical aquaculture ponds. This new assay combined with field-compatible qPCR equipment represent a new technological advancement for early detection of H.akashiwo DNA in prawn farms.