Ecological impacts of an invasive predator explained and predicted by comparative functional responses

Dick, Jaimie T. A.; Gallagher, Kevin; Avlijaš, Sunčica; Clarke, Hazel C.; Lewis, Susan E.; Leung, Sally S. M.; Minchin, Dan; Caffrey, Joe; Alexander, Mhairi E.; Maguire, Cathy; Harrod, Chris; Reid, Neil; Haddaway, Neal R.; Farnsworth, Keith D.; Penk, Marcin R.; Ricciardi, Anthony

doi:10.1007/s10530-012-0332-8

Cited by 165 publications

(235 citation statements)

References 46 publications

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“…This has, however, received little application in invasion ecology, in particular because measures of per capita effects have been lacking . However, as detailed by Dick et al (2013Dick et al ( , 2014, the per capita effect of an invasive species may be quantified by its 'Functional Response' (FR), a classic metric used in ecology to describe and quantify the per capita effect of a predator on its prey as the density of the prey increases (Solomon 1949;Holling 1959a,b), but which can be applied across all taxonomic and trophic groups in any consumer/resource interaction (Dick et al , 2017. Together with the 'Numerical Response' (NR), which describes the change in a predator population as the density of prey increases, this forms the 'Total Response' (TR), such that:…”

Section: Introductionmentioning

confidence: 99%

“…bloody red shrimp Hemimysis anomala, Dick et al 2013; largemouth bass Micropterus salmoides, Alexander et al 2014a, b; killer shrimp Dikerogammarus villosus, Dodd et al 2014; golden apple snail Pomacea canaliculata Xu et al 2016); these invasive consumers show significantly higher FRs than trophically analogous native consumers. However, ecological impacts, such as by predators, will be the product of their per capita effects and the number of individuals having those effects; both must be quantified to elucidate overall effects.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the ecological impacts of invasive species based on their functional responses and abundances

Laverty

Green

Dick³

et al. 2017

Biol Invasions

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Invasive species management requires allocation of limited resources towards the proactive mitigation of those species that could elicit the highest ecological impacts. However, we lack predictive capacity with respect to the identities and degree of ecological impacts of invasive species. Here, we combine the relative per capita effects and relative field abundances of invader as compared to native species into a new metric, ''Relative Impact Potential'' (RIP), and test whether this metric can reliably predict high impact invaders. This metric tests the impact of invaders relative to the baseline impacts of natives on the broader ecological community. We first derived the functional responses (i.e. per capita effects) of two ecologically damaging invasive fish species in Europe, the Ponto-Caspian round goby (Neogobius melanostomus) and Asian topmouth gudgeon (Pseudorasbora parva), and their native trophic analogues, the bullhead (Cottus gobio; also C. bairdi) and bitterling (Rhodeus amarus), towards several prey species. This establishes the existence and relative strengths of the predator-prey relationships. Then, we derived ecologically comparable field abundance estimates of the invader and native fish from surveys and literature. This establishes the multipliers for the above per capita effects. Despite both predators having known 123Biol Invasions (2017) 19:1653-1665 DOI 10.1007/s10530-017-1378 severe detrimental field impacts, their functional responses alone were of modest predictive power in this regard; however, incorporation of their abundances relative to natives into the RIP metric gave high predictive power. We present invader/native RIP biplots that provide an intuitive visualisation of comparisons among the invasive and native species, reflecting the known broad ecological impacts of the invaders. Thus, we provide a mechanistic understanding of invasive species impacts and a predictive tool for use by practitioners, for example, in risk assessments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessing the ecological impacts of invasive species based on their functional responses and abundances

Laverty

Green

Dick³

et al. 2017

Biol Invasions

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“…Prediction of consumer impact has been assessed through the use of comparative functional response analyses (Smout et al 2010;Alexander et al 2012;Alexander et al 2013;Dick et al 2013;Dick et al 2014;Laverty et al 2014;Wasserman et al 2016a, b;Dick et al 2017). This method has been pioneered for the prediction of invasive species impacts in comparison to trophically analogous native species Paterson et al 2015;Dick et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Functional response refers to the rate of consumption of a resource with regards to resource density (Solomon 1949;Holling 1959). It is clear that species with a higher functional response (e.g., higher attack rates, lower handling times, higher asymptote) have a higher impact potential (Bollache et al 2008;Haddaway et al 2012;Dick et al 2013). Functional responses are categorised into: the Type I rectilinear response, usually only found in filter feeders where resource consumption is not limited by handling time (Jeschke et al 2004); the Type II inversely density dependent response with high prey consumption at low densities; and Type III sigmoidal, positively density dependent response whereupon prey have a low-density refuge (Oaten and Murdoch 1975).…”

Section: Introductionmentioning

confidence: 99%

“…Functional responses are categorised into: the Type I rectilinear response, usually only found in filter feeders where resource consumption is not limited by handling time (Jeschke et al 2004); the Type II inversely density dependent response with high prey consumption at low densities; and Type III sigmoidal, positively density dependent response whereupon prey have a low-density refuge (Oaten and Murdoch 1975). Within these response types, it is also possible to quantify the associated parameters of attack rate, handling time and maximum feeding rates (Juliano 2001;Dick et al 2013). Functional response analysis therefore presents itself as a robust assessment method whereupon ecological impact can be explained and predicted across numerous biotic and abiotic contexts Dick et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Effects of acute and chronic temperature changes on the functional responses of the dogfish Scyliorhinus canicula (Linnaeus, 1758) towards amphipod prey Echinogammarus marinus (Leach, 1815)

South

Dick

2017

Environ Biol Fish

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Predation is a strong driver of population dynamics and community structure and it is essential to reliably quantify and predict predation impacts on prey populations in a changing thermal landscape. Here, we used comparative functional response analyses to assess how predator-prey interactions between dogfish and invertebrate prey change under different warming scenarios. The Functional Response Type, attack rate, handling time and maximum feeding rate estimates were calculated for Scyliorhinus canicula preying upon Echinogammarus marinus under temperatures of 11.3°C and 16.3°C, which represent both the potential daily variation and predicted higher summer temperatures within Strangford Lough, N. Ireland. A two x two design of BPredator Acclimated^, BPrey Acclimated^, BBoth Acclimated^, and BBoth Unacclimated^was implemented to test functional responses to temperature rise. Attack rate was higher at 11.3°C than at 16.3°C, but handling time was lower and maximum feeding rates were higher at 16.3°C. Non-acclimated predators had similar maximum feeding rate towards nonacclimated and acclimated prey, whereas acclimated predators had significantly higher maximum feeding rates towards acclimated prey as compared to nonacclimated prey. Results suggests that the predator attack rate is decreased by increasing temperature but when both predator and prey are acclimated the shorter handling times considerably increase predator impact. The functional response of the fish changed from Type II to Type III with an increase in temperature, except when only the prey were acclimated. This change from population destabilizing Type II to more stabilizing Type III could confer protection to prey at low densities but increase the maximum feeding rate by Scyliorhinus canicula in the future. However, predator movement between different thermal regimes may maintain a Type II response, albeit with a lower maximum feeding rate. This has implications for the way the increasing population Scyliorhinus canicula in the Irish Sea may exploit valuable fisheries stocks in the future.

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The ethological trap: functional and numerical responses of highly efficient invasive predators driving prey extinctions

Spencer

Dyke

Thompson

2016

Ecological Applications

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Ecological traps are threats to organisms, and exist in a range of biological systems. A subset of ecological trap theory is the "ethological trap," whereby behaviors canalized by past natural selection become traps when environments change rapidly. Invasive predators are major threats to imperiled species and their ability to exploit canalized behaviors of naive prey is particularly important for the establishment of the predator and the decline of the native prey. Our study uses ecological theory to demonstrate that invasive predator controls require shifts in management priorities. Total predation rate (i.e., total response) is the product of both the functional response and numerical response of predators to prey. Functional responses are the changes in the rate of prey consumption by individual predators, relative to prey abundance. Numerical responses are the aggregative rates of prey consumption by all predators relative to prey density, which change with predator density via reproduction or migration, in response to changes in prey density. Traditional invasive predator management methods focus on reducing predator populations, and thus manage for numerical responses. These management efforts fail to manage for functional responses, and may not eliminate impacts of highly efficient individual predators. We explore this problem by modeling the impacts of functional and numerical responses of invasive foxes depredating imperiled Australian turtle nests. Foxes exhibit exceptionally efficient functional responses. A single fox can destroy >95% of turtle nests in a nesting area, which eliminates juvenile recruitment. In this case, the ethological trap is the "Arribada" nesting strategy, an emergent behavior whereby most turtles in a population nest simultaneously in the same nesting grounds. Our models show that Arribada nesting events do not oversaturate foxes, and small numbers of foxes depredate all of the nests in a given Arribada. Widely scattering nests may reduce fox predation rates, but the long generation times of turtles combined with their rapid recent decline suggests that evolutionary responses in nesting strategy may be unlikely. Our study demonstrates that reducing populations of highly efficient invasive predators is insufficient for preserving native prey species. Instead, management must reduce individual predator efficiency, independent of reducing predator population size.

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Ecological impacts of an invasive predator explained and predicted by comparative functional responses

Cited by 165 publications

References 46 publications

Assessing the ecological impacts of invasive species based on their functional responses and abundances

Assessing the ecological impacts of invasive species based on their functional responses and abundances

Effects of acute and chronic temperature changes on the functional responses of the dogfish Scyliorhinus canicula (Linnaeus, 1758) towards amphipod prey Echinogammarus marinus (Leach, 1815)

The ethological trap: functional and numerical responses of highly efficient invasive predators driving prey extinctions

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