Environmental DNA surveys help to identify winter hibernacula of a temperate freshwater turtle

Feng, Wenxi; Bulté, Grégory; Lougheed, Stephen C.

doi:10.1002/edn3.58

Cited by 24 publications

(18 citation statements)

References 38 publications

(38 reference statements)

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“…Environmental DNA methods have also been used to locate over-wintering sites of freshwater turtles. Feng et al [ 28 ] detected the northern map turtle eDNA from water samples collected under ice. Detections were then confirmed by visual surveys using remotely operated vehicles [ 28 ].…”

Section: Discussionmentioning

confidence: 99%

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Environmental DNA analysis confirms extant populations of the cryptic Irwin’s turtle within its historical range

et al. 2022

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Background Approximately 50% of freshwater turtles worldwide are currently threatened by habitat loss, rural development and altered stream flows. Paradoxically, reptiles are understudied organisms, with many species lacking basic geographic distribution and abundance data. The iconic Irwin’s turtle, Elseya irwini, belongs to a unique group of Australian endemic freshwater turtles capable of cloacal respiration. Water resource development, increased presence of saltwater crocodiles and its cryptic behaviour, have made sampling for Irwin’s turtle in parts of its range problematic, resulting in no confirmed detections across much of its known range for > 25 years. Here, we used environmental DNA (eDNA) analysis for E. irwini detection along its historical and contemporary distribution in the Burdekin, Bowen and Broken River catchments and tributaries. Five replicate water samples were collected at 37 sites across those three river catchments. Environmental DNA was extracted using a glycogen-aided precipitation method and screened for the presence of E. irwini through an eDNA assay targeting a 127 base pair-long fragment of the NADH dehydrogenase 4 (ND4) mitochondrial gene. Results Elseya irwini eDNA was detected at sites within its historic distribution in the lower Burdekin River, where the species had not been formally recorded for > 25 years, indicating the species still inhabits the lower Burdekin area. We also found higher levels of E. iriwni eDNA within its contemporary distribution in the Bowen and Broken Rivers, matching the prevailing scientific view that these areas host larger populations of E. irwini. Conclusions This study constitutes the first scientific evidence of E. irwini presence in the lower Burdekin since the original type specimens were collected as part of its formal description, shortly after the construction of the Burdekin Falls Dam. From the higher percentage of positive detections in the upper reaches of the Broken River (Urannah Creek), we conclude that this area constitutes the core habitat area for the species. Our field protocol comprises a user-friendly, time-effective sampling method. Finally, due to safety risks associated with traditional turtle sampling methods in the Burdekin River (e.g., estuarine crocodiles) we propose eDNA sampling as the most pragmatic detection method available for E. irwini.

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Section: Discussionmentioning

confidence: 99%

“…Feng et al [ 28 ] detected the northern map turtle eDNA from water samples collected under ice. Detections were then confirmed by visual surveys using remotely operated vehicles [ 28 ]. Similarly, Tarof et al [ 25 ] detected eDNA of a threatened freshwater turtle at brumation sites with no previous records of species presence.…”

Section: Discussionmentioning

confidence: 99%

Environmental DNA analysis confirms extant populations of the cryptic Irwin’s turtle within its historical range

et al. 2022

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“…Our filtration protocol was adapted from Turner et al [ 39 ] and Feng et al [ 46 ]. We filtered water samples for environmental DNA using IsoporeTM polycarbonate tract-etched (PCTE) membrane filters (1.2-μm pore size, 47-mm diameter, from Millipore-Sigma, Oakville, ON, Canada), housed in a 47-mm in-line filter holder (Pall Corporation, Port Washington, NY, USA) and passed through with a portable peristaltic pump (Wattera, Mississauga, ON, Canada).…”

Section: Methodsmentioning

confidence: 99%

Depth-Dependent Spatiotemporal Dynamics of Overwintering Pelagic Microcystis in a Temperate Water Body

et al. 2021

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Cyanobacteria in the genus Microcystis are dominant components of many harmful algal blooms worldwide. Their pelagic–benthic life cycle helps them survive periods of adverse conditions and contributes greatly to their ecological success. Many studies on Microcystis overwintering have focused on benthic colonies and suggest that sediment serves as the major inoculum for subsequent summer blooms. However, the contemporaneous overwintering pelagic population may be important as well but is understudied. In this study, we investigated near-surface and near-bottom pelagic population dynamics of both microcystin-producing Microcystis and total Microcystis over six weeks in winter at Dog Lake (South Frontenac, ON, Canada). We quantified relative Microcystis concentrations using real-time PCR. Our results showed that the spatiotemporal distribution of overwintering pelagic Microcystis was depth dependent. The abundance of near-bottom pelagic Microcystis declined with increased depth with no influence of depth on near-surface Microcystis abundance. In the shallow region of the lake (<10 m), most pelagic Microcystis was found near the lake bottom (>90%). However, the proportion of near-surface Microcystis rose sharply to over 60% as the depth increased to approximately 18 m. The depth-dependent distribution pattern was found to be similar in both microcystin-producing Microcystis and total Microcystis. Our results suggest the top of the water column may be a more significant contributor of Microcystis recruitment inoculum than previously thought and merits more attention in early CHAB characterization and remediation.

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“…A total of 12 water samples were collected from each stream (4 samples/year × 3 years = 12 samples). One liter of water was collected from the water column [13,[31][32][33] using a sterile 50-mL conical tube. At the same time, water temperature and pH were measured using a waterproof temperature/pH meter (Eutech pHTestr 30).…”

Section: Sample Collection and Processingmentioning

confidence: 99%

“…However, there is a trade-off between water volume and factors such as filtration efficiency and risk of PCR inhibition. The use of relatively small sampling volumes is common in eDNA studies, with sampling volumes of <1 L [75,76] to 1-2 L [13,[31][32][33]77]. Ma ¨chler et al [69] suggested the optimal sampling volume depends on the species-habitat combination, therefore, pilot studies are required for each study system.…”

Section: False Negativesmentioning

confidence: 99%

Using eDNA techniques to find the endangered big-headed turtle (Platysternon megacephalum)

Lam¹,

Sung²,

Fong³

2022

PLoS ONE

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We evaluate the efficacy of environmental DNA (eDNA) techniques to locate wild populations and estimate the population size of the endangered big-headed turtle (Platysternon megacephalum) in Hong Kong. The results from this study are important for identifying priority sites for protection and further research. Additionally, we assess the impact of two environmental variables (temperature and pH) on eDNA quantity. We surveyed 34 streams for three years, sampling four times each year. Four new populations were first identified with eDNA analysis, and then verified by field surveys. Our multi-year survey highlights that eDNA detection can be inconsistent over time, even in streams with known populations. There was no significant relationship between eDNA quantity and the environmental variables tested. Lastly, our results suggest that eDNA methods remain promising to estimate population size, since number of positive detections were positively correlated with population size in streams with known populations. We conclude that eDNA methods are powerful, but care must be taken when interpreting field results as they are affected by species ecology and environmental conditions.

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Environmental DNA surveys help to identify winter hibernacula of a temperate freshwater turtle

Cited by 24 publications

References 38 publications

Environmental DNA analysis confirms extant populations of the cryptic Irwin’s turtle within its historical range

Environmental DNA analysis confirms extant populations of the cryptic Irwin’s turtle within its historical range

Depth-Dependent Spatiotemporal Dynamics of Overwintering Pelagic Microcystis in a Temperate Water Body

Using eDNA techniques to find the endangered big-headed turtle (Platysternon megacephalum)

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