Investigating environmental DNA & RNA fate for biosecurity applications: A case study using the Mediterranean fanworm Sabella spallanzanii

Ms Michelle Scriver^1,2, Dr. Anastasija  Zaiko^1,2, Dr. Xavier Pochon^1,2, Dr. Vanessa Arranz³, Dr. Ulla von Ammon¹

¹Cawthron Institute, 98 Halifax Street East, Nelson, 7010, New Zealand, ²Institute of Marine Science, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand, ³School of Natural and Computational Sciences, Massey University Auckland, Albany, Auckland, 0745, New Zealand

Abstract:

The proliferation of marine non-indigenous species (NIS) has been classified as a major threat to local biodiversity, human health, and the economy. Early detection and monitoring of marine NIS are essential for effective biosecurity management strategies. Many countries have started implementing powerful non-invasive molecular surveillance technologies using environmental DNA and RNA (eDNA/eRNA) as part of marine biosecurity programmes. However, few studies have been conducted for assessing eDNA/eRNA degradation and persistence in marine environments. Furthermore, little is known about the fate of eDNA/eRNA molecules during post-sampling processes (filtration, storage and transport) and the possible implications for the detectability of a target species. To address these questions, an experiment was conducted in an Auckland marina known as a hotspot for the invasive Mediterranean fanworm S. spallanzanii. Semi-permeable dialysis bags filled with 500 mL of ambient seawater were deployed in the marina and a subset of bags were kept on ice to mimic the storage conditions in the field. Samples from each treatment were processed in triplicates at 0, 3, 6, 9, 12, and 24 hours for both eDNA and eRNA isolation, quality measurements and subsequent real-time quantification of S. spallanzanii using droplet digital PCR analysis. The fading patterns and detectability of the targeted eDNA/eRNA signals over time were evaluated from both in situ and ice-stored samples.  These results are critical to reduce false positive detections, understand the dispersal of eDNA/eRNA in marine waters, enhance detection probabilities by adjusting surveillance design and predict the location of source populations.

Biography:

Michelle Scriver, a PhD Candidate, recently moved to New Zealand to begin her PhD project focused on optimizing molecular-based marine biosecurity surveillance. Her research is part of the detect compartment of the Marine Biosecurity Toolbox programme. Originally from Canada, Michelle has spent the last five years gaining work experience in the collaborative gene therapy industry in the United States. Her drive to continue to learn and her previous experience with eDNA and invasive species, has lead her to her current PhD Position at the Cawthron Institute. Her project will focus on optimizing the current eDNA/eRNA workflow and developing a better understanding of how, where and when to sample.