A global meta-analysis of the ecological impacts of nonnative crayfish

Twardochleb, Laura A.; Olden, Julian D.; Larson, Eric R.

doi:10.1899/12-203.1

Cited by 235 publications

(239 citation statements)

References 74 publications

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“…everything apart from decomposition and primary productivity) except invertebrate density, which was greater for native crayfish. These results are consistent with the findings of Twardochleb et al (2013) who also found that invasive crayfish caused greater reductions in the biomass and/ or growth rate of other invertebrates and fish, and greater increases in algal biomass than native crayfish. The relative impacts of invasive and native crayfish on decomposition rates, primary productivity, invertebrate diversity and amphibian egg and larval survival were not evaluated by Twardochleb et al (2013).…”

Section: Discussionsupporting

confidence: 92%

“…These results are consistent with the findings of Twardochleb et al (2013) who also found that invasive crayfish caused greater reductions in the biomass and/ or growth rate of other invertebrates and fish, and greater increases in algal biomass than native crayfish. The relative impacts of invasive and native crayfish on decomposition rates, primary productivity, invertebrate diversity and amphibian egg and larval survival were not evaluated by Twardochleb et al (2013). Greater impacts of invasive than native species are expected as populations tend to evolve to minimize the negative effects of interspecific interactions on individual fitness (Connell 1980;Futuyma and Slatkin 1983;Rummel and Roughgarden 1985;Shea and Chesson 2002), and community composition should adjust through Fig.…”

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

“…A recent meta-analysis on the impacts of crayfish on aquatic ecosystems found that invasive crayfish reduced the abundance and/or biomass of aquatic macrophytes and invertebrates and reduced the abundance and/or growth rate of fish and amphibians but did not consistently affect algal biomass (Twardochleb et al 2013). The impacts of native crayfish were, however, only considered in relation to those of non-native species (Twardochleb et al 2013). Overall, invasive crayfish caused greater reductions in invertebrate and fish biomass and abundance and greater increases in algal biomass than native crayfish; however, results were variable and comparisons were only made between specific non-native-native crayfish species pairs (Twardochleb et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…The impacts of native crayfish were, however, only considered in relation to those of non-native species (Twardochleb et al 2013). Overall, invasive crayfish caused greater reductions in invertebrate and fish biomass and abundance and greater increases in algal biomass than native crayfish; however, results were variable and comparisons were only made between specific non-native-native crayfish species pairs (Twardochleb et al 2013). With the demand for population relocations of native crayfish predicted to increase with intensified pressure from invasive crayfish species it is essential to collate and synthesise all available data on the ecological impacts of native species.…”

Section: Introductionmentioning

confidence: 99%

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Comparing the ecological impacts of native and invasive crayfish: could native species’ translocation do more harm than good?

et al. 2014

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native and invasive crayfish have wide-ranging impacts on aquatic ecosystems that may be exacerbated for invasive species. Subsequent analysis showed that the impacts of invasive crayfish were significantly greater, in comparison to native crayfish, for decomposition and primary productivity but not invertebrate density, biomass and diversity. Overall, our findings reconfirm the ecosystem altering abilities of both native and invasive crayfish, enforcing the need to carefully regulate managed relocations of native species as well as to develop control programs for invasives.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparing the ecological impacts of native and invasive crayfish: could native species’ translocation do more harm than good?

et al. 2014

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

Pritchard

Chadwick

Patmore

et al. 2021

Ecol Sol and Evidence

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1. As crayfish invasions continue to threaten native freshwater biota, a detailed understanding of crayfish distribution and population structure becomes imperative.Nonetheless, most current survey methods provide inadequate demographic data.The quantitative 'Triple Drawdown' (TDD) dewatering method has highlighted the importance of such data, yet practical constraints prevent its large-scale application.2. Here, we introduce the 'Pritchard Trap' , a novel passive sampling method that reliably generates quantitative crayfish population data while requiring substantially lower sampling effort than TDDs. This quadrat-style sampler was extensively tested in headwater streams of North Yorkshire, England, along an invasion gradient for signal crayfish (Pacifastacus leniusculus) from well-established sites to mixed populations of signal crayfish and native white-clawed crayfish (Austropotamobius pallipes).3. The Pritchard Trap was trialled over several time intervals to determine the minimum required trap deployment time. TDDs at the same sites allowed for a robust evaluation of Pritchard Trap sampling accuracy in representing crayfish densities and population structure. 4. The Pritchard Trap successfully sampled both invasive and native crayfish (8-42 mm carapace length). A minimum passive deployment time of 4 days was required. At low crayfish densities (0.5 individuals m −2 ), increased trapping effort was necessary to achieve accurate population density and size class distribution estimates. The Pritchard Trap required substantially less sampling effort (working hours) and resources than the TDD, whilst also posing less risk to non-target species.5. The Pritchard Trap, for the first time, affords logistically simple, truly quantitative investigations of crayfish population demographics for headwater systems. It could be integrated into crayfish research and management, for example to explore density-dependent ecological impacts of invasive crayfish and their managementThis 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.

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Mechanical excavation of wetland habitat failed to eradicate invasive American red swamp crayfish (Procambarus clarkii) in Malta

Caruana,

Camilleri,

Farrugia

et al. 2024

Ecol Sol and Evidence

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Invasive crayfish are an important ecological concern in many freshwater ecosystems. Many efforts have been made to eradicate them, but there is very little documentation of the effectiveness of these efforts. Between 2019 and 2020, a restoration project funded by the European Regional Development Fund tried to eradicate invasive American red swamp crayfish Procambarus clarkii from the Fiddien valley system in Malta by mechanically excavating the valley's stream bed and exporting contaminated debris securely off‐site to a dry quarry. Three years post‐intervention, we systematically surveyed the valley system to explore the distribution and relative abundance of the invasive crayfish population. We placed traps in a stratified random sample of stream segments (both those that were included in the original restoration project and those that were not) and recorded catch per unit effort (crayfish caught per trap night) and the size/frequency distribution of crayfish caught. The invasive crayfish were still abundant in the upper reaches of the valley system, and, despite the excavation effort, crayfish were present at the highest relative abundance (4.3–14.8 CPUE, median = 12.3) within the restored area. Despite substantial effort and spending of more than 700,000 €, mechanical excavation did not eradicate invasive crayfish populations. We urge caution for future projects planning to attempt crayfish eradication using this approach and call for much greater impact evaluation, and at the very least post‐project monitoring, to ensure lessons can be learnt from such failures in future.

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A global meta-analysis of the ecological impacts of nonnative crayfish

Cited by 235 publications

References 74 publications

Comparing the ecological impacts of native and invasive crayfish: could native species’ translocation do more harm than good?

Comparing the ecological impacts of native and invasive crayfish: could native species’ translocation do more harm than good?

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

Mechanical excavation of wetland habitat failed to eradicate invasive American red swamp crayfish (Procambarus clarkii) in Malta

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