The ‘Pritchard Trap’: A novel quantitative survey method for crayfish

Pritchard, Eleri G.; Chadwick, Daniel D. A.; Patmore, Ian R.; Chadwick, Michael A.; Bradley, Paul M.; Sayer, Carl D.; Axmacher, Jan C.

doi:10.1002/2688-8319.12070

Cited by 4 publications

(3 citation statements)

References 44 publications

(78 reference statements)

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“…When abundant, crayfish are easily trapped or detected with visual surveys (e.g., Short, 2021), but crayfish traps also risk mortality of non-target organisms (Tréguier et al, 2014). When rare, crayfish can escape detection through visual surveys or trapping because they can burrow in sediment and find refugia for up to several months (Pritchard et al, 2021). This can potentially lead to false negative detection in early stages of invasion, or false successes of eradication programs for invasive species (e.g., Nunes et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Environmental DNA reveals invasive crayfish microbial associates and ecosystem‐wide biodiversity before and after eradication

et al. 2023

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Biodiversity monitoring in conservation projects is essential to understand environmental health, complexity, and recovery. However, traditional field surveys can be expensive, time‐consuming, biased toward visual detection, and/or only measure a limited set of taxa. Environmental DNA (eDNA) methods provide a new approach to biodiversity monitoring that has the potential to sample a taxonomically broader set of organisms with a similar effort, but many of these approaches are still in the early stages of development and testing. Here, we used multi‐locus eDNA metabarcoding to understand how the removal of invasive red swamp crayfish using cypermethrin pesticide impacts local biodiversity of a desert oasis ecosystem, as well as to detect crayfish both directly and indirectly. We tracked crayfish DNA signatures, microbial DNA associated with crayfish, and biodiversity of plant, fungal, animal, and bacterial communities through time. We were unsuccessful in detecting crayfish directly in either control tanks or oases using targeted metabarcoding primers for invertebrates and eukaryotes, similar to previous studies which have shown variable levels of success in detecting crayfish from environmental samples. However, we were successful in discerning a suite of 90 crayfish‐associated taxa to serve as candidate bioindicators of invasive presence using 16S and fungal ITS2 metabarcoding. Ranking these 90 taxa by their geographic distribution in eDNA surveys and by evidence of crayfish associations in the literature, we support nine taxa to be high ranking, and suggest they be prioritized in future biomonitoring. Biodiversity analyses from five metabarcode loci including plants, animals, and both prokaryotic and eukaryotic microbes showed that communities differed but that species richness remained relatively similar between oases through time. Our results reveal that, while there are limitations of eDNA approaches to detect crayfish and other invasive species, microbial bioindicators offer a largely untapped biomonitoring opportunity for invasive species management, adding a valuable resource to a conservation manager's toolkit.

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Section: Introductionmentioning

confidence: 99%

Environmental DNA reveals invasive crayfish microbial associates and ecosystem‐wide biodiversity before and after eradication

et al. 2023

View full text Add to dashboard Cite

show abstract

“…When abundant, crayfish are easily trapped or detected with visual surveys (e.g. Short, 2021), but, when rare, crayfish can escape detection because they can burrow in sediment and find refugia for up to several months (Pritchard et al, 2021), potentially leading to false successes of eradication programs for invasive species (e.g. Nunes et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Short, 2021), but crayfish traps also risk mortality of non-target organisms (Tréguier et al, 2014). When rare, crayfish can escape detection through visual surveys or trapping because they can burrow in sediment and find refugia for up to several months (Pritchard et al, 2021), potentially leading to false negative detection in early stages of invasion, or false successes of eradication programs for invasive species (e.g. Nunes et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Environmental DNA reveals invasive crayfish microbial associates and ecosystem-wide biodiversity before and after eradication

Ballare

Worth

Ruiz‐Ramos

et al. 2022

Preprint

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Biodiversity monitoring in conservation projects is essential to understand environmental status and recovery. However, traditional field surveys can be biased towards visual detection and/or focused on measuring the biodiversity of a limited set of taxa. Environmental DNA (eDNA) methods provide a new approach to biodiversity monitoring that has the potential to sample a taxonomically broader set of organisms with similar effort, but these approaches are still in the early stages of development and testing. Here, we explore the utility of multilocus eDNA metabarcoding to explore the impact on local biodiversity of removal of the red swamp crayfish, a globally invasive species, from a desert oasis ecosystem. We tracked crayfish DNA signatures, microbial DNA associated with crayfish, and biodiversity changes of plant, fungal, animal, and bacterial communities through time. We were unsuccessful in detecting crayfish in control tanks or oases using targeted metabarcoding primers for invertebrates and eukaryotes. Metabarcoding of the 16S (targeting prokaryotes) and the ITS1 (targeting fungi) loci in the invaded oasis and tanks pre-removal were, however, successful in discerning a suite of 90 crayfish-associated taxa to serve as candidate bioindicators of invasive presence. Ranking these 90 taxa by their geographic distribution in eDNA surveys and by evidence of crayfish-associations in the literature, we support 9 taxa to be high-ranking, and suggest they be prioritized in future biomonitoring. Biodiversity analyses from five metabarcode loci including plants, animals, and both prokaryotic and eukaryotic microbes showed that communities differed but that species richness remained relatively similar between oases through time. Our results reveal that, while there are limitations of eDNA approaches to detect crayfish and other invasive species, microbial bioindicators offer a largely untapped biomonitoring opportunity for invasive species management, adding a valuable resource to a conservation manager’s toolkit.

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Assessing methods to improve benthic fish sampling in a stony headwater stream

Pritchard

Chadwick

et al. 2021

Ecol Sol and Evidence

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Electrofishing is a well‐established and widely used method for surveying fish populations. Nonetheless, its effectiveness is impacted by numerous factors, including water chemistry, habitat type and fish species. Both physiological and behavioural responses make bottom‐dwelling ‘benthic’ fish which lack swim bladders (e.g. European bullhead Cottus gobio) particularly difficult to survey by electrofishing. We compare the performance and practicalities of electrofishing for benthic fish at a rocky northern English headwater stream with two sampling methods originally designed for crayfish surveys; the triple drawdown method which involves repeated dewatering of a site, and the Pritchard Trap method which involves sunken traps filled with natural substrate that samples a small, fixed (0.25 m2) area of river bed. Both the Pritchard trapping and triple drawdown methods provided similar high‐density population density estimates for bullhead which were at least 2.5–5 times higher than predicted from electrofishing derived sweep depletion curves. Electrofishing and the triple drawdown method are both resource‐intensive, requiring expensive equipment and a team of trained operatives. These approaches also pose a risk to fish and non‐target organisms. In contrast, Pritchard Traps provide a cost‐effective passive, low risk survey method requiring minimal training and only one operative. Pritchard traps, therefore, show particular promise for benthic fish surveying and monitoring.

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The ‘Pritchard Trap’: A novel quantitative survey method for crayfish

Cited by 4 publications

References 44 publications

Environmental DNA reveals invasive crayfish microbial associates and ecosystem‐wide biodiversity before and after eradication

Environmental DNA reveals invasive crayfish microbial associates and ecosystem‐wide biodiversity before and after eradication

Environmental DNA reveals invasive crayfish microbial associates and ecosystem-wide biodiversity before and after eradication

Assessing methods to improve benthic fish sampling in a stony headwater stream

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