A comparison of the predatory impacts of an invasive and native crab species using a functional response approach

Ens, Nicholas Josiah; Lim, Emily G.; Howard, Brett; Eastham, Tao M.

doi:10.1007/s10530-021-02508-5

Cited by 9 publications

(3 citation statements)

References 35 publications

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“…Invasive species' impacts are often context-dependent, in part mediated by abundance (but also per capita differences; see Howard et al 2018). Reported abundance of green crab in Placentia Bay exceeds that of the species elsewhere in the Canada's eastern provinces (DFO 2011) as well as in western United States and Canada (Yamada et al 2020;Ens et al 2021). Such differences may portend dissimilar ecological impacts.…”

Section: Discussionmentioning

confidence: 99%

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

DeRoy¹,

Crookes²,

Matheson³

et al. 2022

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Characterising interspecific interaction strengths, combined with population abundances of prey and their novel predators, is critical to develop predictive invasion ecology. This is especially true of aquatic invasive species, which can pose a significant threat to the structure and stability of the ecosystems to which they are introduced. Here, we investigated consumer-resource dynamics of two globally-established aquatic invasive species, European green crab (Carcinus maenas) and brown trout (Salmo trutta). We explored the mediating effect of prey density on predatory impact in these invaders relative to functionally analogous native rock crab (Cancer irroratus) and Atlantic salmon (Salmo salar), respectively, feeding on shared prey (Mytilus sp. and Tenebrio molitor, respectively). We subsequently combined feeding rates with each predator’s regional abundance to forecast relative ecological impacts. All predators demonstrated potentially destabilising Type II functional responses towards prey, with native rock crab and invasive brown trout exhibiting greater per capita impacts relative to their trophic analogues. Functional Response Ratios (attack rates divided by handling times) were higher for both invasive species, reflecting greater overall per capita effects compared to natives. Impact projections that incorporated predator abundances with per capita effects predicted severe impacts by European green crabs. However, brown trout, despite possessing higher per capita effects than Atlantic salmon, are projected to have low impact owing to currently low abundances in the sampled watershed. Should brown trout density increase sixfold, we predict it would exert higher impact than Atlantic salmon. Such impact-forecasting metrics and methods are thus vital tools to assist in the determination of current and future adverse impacts associated with aquatic invasive species.

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Section: Discussionmentioning

confidence: 99%

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

DeRoy¹,

Crookes²,

Matheson³

et al. 2022

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“…It also reveals the potential for predators to destabilise prey populations, particularly at low prey densities when predators can find and consume all prey available ( i.e., a Type II functional response) ( Holling, 1959 ; Hassell, 1978 ). Functional responses can differ between invasive and native species, among invasive species, and within species under different contexts ( Haddaway et al, 2012 ; Dick et al, 2013 ; Alexander et al., 2014 ; Howard et al, 2018 ; Howard et al, 2022 ; Ens et al, 2021 ; Chucholl & Chucholl, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…Those that target invasive predators often rely on the study of males ( e.g. , Howard et al, 2018 ; Howard et al., 2022 ; Ens et al, 2021 ; Chucholl & Chucholl, 2021 ). There is a good reason for this bias: the risk of accidental introductions is eliminated if females, especially gravid ones, are not transported to experimental facilities.…”

Section: Introductionmentioning

confidence: 99%

Functional responses of male and female European green crabs suggest potential sex-specific impacts of invasion

Kattler,

Oishi,

Lim

et al. 2023

PeerJ

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Predicting the impacts of predatory invasive species is important for prioritising conservation interventions. Functional response experiments, which examine consumption by predators in relation to prey density, are a useful way to assess the potential strength of novel predator-prey relationships. However, such experiments are often conducted without consideration of sex or only with males to reduce invasion risk. Here, we compared the functional responses of male and female European green crabs (Carcinus maenas), a global invader, feeding on varnish clams (Nuttallia obscurata) to test whether the two sexes have similar potential for impact. We also examined potential correlates of predation behaviour by measuring sex-specific movement and prey choice. Both sexes displayed a Type II hyperbolic functional response, which can destabilise prey populations at low prey densities. However, males and females exhibited some differences in foraging behaviour. Female green crabs had slightly lower attack rates, which were not linked to sex differences in movement, and slightly longer handling times, which were not linked to sex differences in prey choice. These small, non-significant differences nevertheless translated into significantly greater functional response ratios, which are used to predict the ecological impact of invasive species, for males than females. There was no difference in the proportion of clams consumed between males and females with similar crusher claw heights, but females have smaller crusher claws on average, hence they consumed a smaller proportion of clams. Repeated surveys of four populations of European green crabs established in British Columbia, Canada, showed that sex ratio is highly variable. Taken together, these results and population-level modelling suggest that trying to evaluate the potential impact of European green crabs on clam populations by sampling only males could result in overestimation, even in populations that have male-biased sex-ratios. Consumer sex might generally be an important feature to consider when using functional response experiments to forecast the impact of new invasive species, especially those with marked sexual dimorphism that affect foraging.

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Climate change and multiple stressors

de Rivera,

Heath

2024

Ecophysiology of the European Green Crab (Carcinus Maenas) and Related Species

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A comparison of the predatory impacts of an invasive and native crab species using a functional response approach

Cited by 9 publications

References 35 publications

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

Functional responses of male and female European green crabs suggest potential sex-specific impacts of invasion

Climate change and multiple stressors

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A comparison of the predatory impacts of an invasive and native crab species using a functional response approach

Cited by 9 publications

References 35 publications

﻿Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

﻿Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

Functional responses of male and female European green crabs suggest potential sex-specific impacts of invasion

Climate change and multiple stressors

Contact Info

Product

Resources

About

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species

Predatory ability and abundance forecast the ecological impacts of two aquatic invasive species