Quantifying the spatiotemporal detection limits of environmental DNA (eDNA) for aquatic biosecurity surveillance

Expressions of Interest are being sought from potential PhD students to undertake studies on the use of eDNA as a marine biosecurity surveillance tool. We are seeking a motivated and enthusiastic student to conduct both lab and field-based research. Scuba diving and boating experience is an advantage, but not a requirement.

This project will be a collaboration between Murdoch University and the Department of Fisheries. A research budget will be provided along with a $27 000 annual stipend (3 years). If a prospectivestudent secures an APA scholarship through the University then a top-up stipend of $10 000 will be provided and additional funds will be allocated to research. As such, prospective students must be an Australian/New Zealand citizen or an Australian permanent resident and, to be competitive for the scheme, should ideally have a 1st Class Hons Degree and demonstrable research experience.

Supervision team: Prof Simon McKirdy, Adj Prof Justin McDonald, Adj Prof Fred Wells

Background:

As an ocean bound nation Australia relies heavily on maritime transport, with over 95% of our imports and exports carried by sea. The large ocean going vessels that transport these goods represent one of the largest potential vectors of introduced species into Western Australia. Increasing human population andits associated travel, transport and trade requirements, together with increasing pressure on dwindling biosecurity resources translates into a growing risk for the introduction of new aquatic pests, or for their further dispersal within our borders. The introduction and spread of new species into Western Australian waters poses a significant threat to our native biodiversity and can have widespread effects on both the State’s economy and its population’s health. Molecular techniques are increasingly being used as complementary tools in biosecurity surveillance for invasive species.

Organisms constantly leave traces of their DNA (in the form of shedding skin, excretion and gametes during reproduction). These DNA traces in the water and sediment allows for the detection of taxa without morphological identification. Molecular tools can be particularly useful for early detection and rapid identification and discrimination of species, including when diagnostic characters are absent or challenging, such as early life stages, when only part of the animal is available or in the presence of very similar native species.This also has significant economic implications for industry when operations are delayed awaiting confirmation of IMS detections.

The Department of Fisheries Biosecurity group is transitioning more towards the complimentary use of eDNA and other molecular tools as part of its surveillance activities to protect WA aquatic environments. The goal of the proposed PhD project is answer key questions to issues (e.g. type 1 and 2 errors) to refine and strengthen the marine biosecurity eDNA surveillance activities.

Objectives/Aims:

Several key questions remain un-answered that will aid in increasing the capabilities of eDNA in marine biosecurity surveillance. These include:

  • How long does DNA persist in the water column?
  • What are the dispersive properties of eDNA in the marine environment, and what hydrodynamic parameters are important in the surveillance of IMS eDNA?
  • How do changes in seawater temperature and salinity, and other environmental factors like solar radiation influence the detection (viability) of IMS eDNA?
  • What are the thresholds associated with degraded eDNA to assign confidence in any detection?
  • Can eDNA surveillance be used to estimate IMS abundance and/or biomass?

Methods:

Investigations to solve the above questions will require both laboratory and field based experimentation. It is envisaged that aquaria experiments would be used to explore the factors influencing the properties and degradation of IMS eDNA. Field based testing of laboratory results would examine real world application and validity of IMS eDNA surveillance. Using results from aquaria and field based experiments; numerical simulations may be used to understand dispersal characteristics and the influence on IMS surveillance.

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