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Flow regimes control the establishment of invasive crayfish and alter their effects on lotic macroinvertebrate communities

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journal contribution
posted on 13.01.2022, 10:12 by Kate MathersKate Mathers, James C White, Riccardo Fornaroli, Richard Chadd
Invasive non-native species (INNS) threaten biodiversity and ecosystem functioning globally. However, there remains a pressing need to understand the environmental factors controlling the dispersal, successful establishment and subsequent ecological impacts of INNS for receiving ecosystems. Here, we examine how region-wide flow regime magnitudes facilitate the successful establishment of an invasive crayfish species (Pacifastacus leniusculus, signal crayfish) in England (UK). We also consider the interactive effects of invasive crayfish with flow regime variations on the structural and functional diversity of macroinvertebrate communities.
Low-flow magnitudes increased the likelihood of P. leniusculus establishment, with 80% of recorded invasion dates falling in years with flow magnitudes below average (low- and low-moderate flow classes), whilst only 1.6% occurred in high-flow years.
Temporal trajectories of structural and functional macroinvertebrate responses in invaded rivers demonstrated reduced diversity compared to control rivers. Lower taxonomic and functional richness measures typically coincided with periods of low discharge in invaded rivers and were greatest during regionally high-flows.
Macroinvertebrate communities displayed significant structural and functional responses to the interaction between invasive crayfish and flow regime variations. Specifically, a number of low- and high-flow indices yielded significant associations, highlighting the role of extreme hydrological events in shaping INNS effects on receiving ecosystems. We also detected greater ecological effects of invasive crayfish under hydrologically stable conditions. Importantly, and for the first time, we observed that invasive crayfish reversed macroinvertebrate community responses to flow regime cues (e.g. discharge fall rate and minimum flows in the preceding 180 days).
Synthesis and applications. Results from this study indicate that low-flow events facilitate the spread/establishment of invasive crayfish and correspond with greater ecological effects for receiving ecosystems. Given that low-flow events are predicted to increase in intensity, duration and frequency over the 21st century, our results highlight the potential threat that invasive crayfish may pose under future hydroclimatic changes. Managing river flow regimes effectively (including maintaining higher flow events and flow variability) is likely to be vital in conserving ecological diversity following crayfish invasion.



  • Social Sciences and Humanities


  • Geography and Environment

Published in

Journal of Applied Ecology






886 - 902




AM (Accepted Manuscript)

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© British Ecological Society

Publisher statement

This is the peer reviewed version of the following article: MATHERS, K. ... et al, 2020. Flow regimes control the establishment of invasive crayfish and alter their effects on lotic macroinvertebrate communities. Journal of Applied Ecology, 57 (5), pp.886-902, which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

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Dr Kate Mathers. Deposit date: 12 January 2022