Villacorta Rath, Cecilia, Adekunle, Adeshina I., Edmunds, Richard C., Strugnell, Jan M., Schwarzkopf, Lin, and Burrows, Damien (2020) Can environmental DNA be used to detect first arrivals of the cane toad, Rhinella marina, into novel locations? Environmental DNA, 2 (4). pp. 635-646.

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Abstract

Eradicating invasive species is difficult, but success is more likely when populations are small after arrival. The cane toad, Rhinella marina, is an invasive pest species that threatens native fauna worldwide. Increasingly, environmental DNA (eDNA) is used as a technique to monitor the presence of invasive species given its power to detect low numbers of individuals. We aimed to investigate eDNA persistence in freshwater at three different temperatures (25, 30 and 35°C) and eDNA detection thresholds for R. marina using controlled experiments in aquaria. For the latter, two water volumes and two cane toad exposure times were used (800 or 200 L volume with 5 or 30 min exposure). A 15‐ml water sample was collected from each replicated aquaria and preserved with 5 ml Longmire's buffer. Environmental DNA was extracted and four technical quantitative PCR replicates were analyzed targeting the cane toad 16S rDNA mitochondrial gene. Environmental DNA decayed rapidly in water and was reliably detected for up to 3 days after cane toad removal, regardless of the temperature treatment. Also, cane toad eDNA was detected in the water after a 5‐min initial exposure of a single individual in 800 L of water. Under the physical parameters tested here, a positive detection means that a cane toad has been in contact with the water body between 1 and 3 days prior to the sampling event. The results of the present study show the importance of eDNA for determining the presence of a species that occurs at low abundance in a small water body, such as at the onset of a cane toad invasion.

Item ID:	63738
Item Type:	Article (Research - C1)
ISSN:	2637-4943
Keywords:	detectability, eDNA persistence, environmental DNA, first incursions, invasive species, monitoring
Copyright Information:	© 2020 The Authors. Environmental DNA published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Funders:	National Environmental Science Program (NESP)
Projects and Grants:	NESP Project 4.3
Date Deposited:	20 Aug 2020 04:00
FoR Codes:	41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410402 Environmental assessment and monitoring @ 35% 41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410202 Biosecurity science and invasive species ecology @ 35% 31 BIOLOGICAL SCIENCES > 3105 Genetics > 310599 Genetics not elsewhere classified @ 30%
SEO Codes:	96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960406 Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments @ 50% 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960506 Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments @ 50%
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