Predatory functional response and prey choice identify predation differences between native/invasive and parasitised/unparasitised crayfish.

Neal R Haddaway,Hannah M Griffiths,Alison M Dunn,Robert J G Mortimer,Ruth H Wilcox,Martin Christmas,Rachael E A Heptonstall,Sean A Rands

doi:10.1371/journal.pone.0032229

Neal R Haddaway, Hannah M Griffiths + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0032229

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Journal: PloS one	Publication Date: Feb 16, 2012
Citations: 99	License type: CC BY 4.0

Affiliation: University of Leeds, Bangor University, Environment Agency

Abstract

BackgroundInvasive predators may change the structure of invaded communities through predation and competition with native species. In Europe, the invasive signal crayfish Pacifastacus leniusculus is excluding the native white clawed crayfish Austropotamobius pallipes.Methodology and Principal FindingsThis study compared the predatory functional responses and prey choice of native and invasive crayfish and measured impacts of parasitism on the predatory strength of the native species. Invasive crayfish showed a higher (>10%) prey (Gammarus pulex) intake rate than (size matched) natives, reflecting a shorter (16%) prey handling time. The native crayfish also showed greater selection for crustacean prey over molluscs and bloodworm, whereas the invasive species was a more generalist predator. A. pallipes parasitised by the microsporidian parasite Thelohania contejeani showed a 30% reduction in prey intake. We suggest that this results from parasite-induced muscle damage, and this is supported by a reduced (38%) attack rate and increased (30%) prey handling time.Conclusions and SignificanceOur results indicate that the per capita (i.e., functional response) difference between the species may contribute to success of the invader and extinction of the native species, as well as decreased biodiversity and biomass in invaded rivers. In addition, the reduced predatory strength of parasitized natives may impair their competitive abilities, facilitating exclusion by the invader.

Highlights

Biological invasions are one of the main causes of biodiversity loss and changes in community structure [1,2,3,4]
Our results indicate that the per capita difference between the species may contribute to success of the invader and extinction of the native species, as well as decreased biodiversity and biomass in invaded rivers
In the UK, P. leniusculus is replacing the native crayfish Austropotamobius pallipes through competition for habitat and food, and through outbreaks of crayfish plague, for which P. leniusculus acts as a reservoir [18]

Summary

Introduction

Biological invasions are one of the main causes of biodiversity loss and changes in community structure [1,2,3,4]. Invasive predators can change the structure of the invaded community through predation pressure on native prey as well as through competition with native predators [6,7]. Peay et al [14] observed a decrease in the abundance of juvenile trout (Salmo spp) following the replacement of native crayfish by P. leniusculus in Yorkshire. It is not clear whether these negative effects reflect the high densities attained by the invader present in many water bodies [19] or a higher per capita impact relative to the native A. pallipes. In Europe, the invasive signal crayfish Pacifastacus leniusculus is excluding the native white clawed crayfish Austropotamobius pallipes

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