Nonconsumptive effects of a predator weaken then rebound over time

Kimbro, David L.; Grabowski, Jonathan H.; Hughes, A. Randall; Piehler, Michael F.; White, J. Wilson

doi:10.1002/ecy.1702

Cited by 30 publications

(26 citation statements)

References 49 publications

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“…Of course, the relative importance of TMIIs and DMIIs will depend on the particular taxa involved, the energetic requirements of prey, and the frequency and duration of these interactions (Kimbro et al. ).…”

Section: Discussionmentioning

confidence: 99%

Fish predators reduce kelp frond loss via a trait‐mediated trophic cascade

Haggerty

Anderson

Long

2018

Ecology

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Although trophic cascades were originally believed to be driven only by predators eating prey, there is mounting evidence that such cascades can be generated in large part via non-consumptive effects. This is especially important in cascades affecting habitat-forming foundation species that in turn, influence associated communities. Here, we use laboratory and field experiments to identify a trait-mediated indirect interaction between predators and an abundant kelp in a marine temperate reef system. Predation risk from a microcarnivorous fish, the señorita, suppressed grazing by the host-specific seaweed limpet, which in turn, influenced frond loss of the habitat-forming feather boa kelp. This trophic cascade was pronounced because minor amounts of limpet grazing decreased the strength required to break kelp fronds. Cues from fish predators mitigated kelp loss by decreasing limpet grazing; we found 86% of this indirect interaction between predator and kelp was attributed to the non-consumptive effect in the laboratory and 56% when applying the same effect size calculations to the field. In field manipulations, the non-consumptive effect of señorita was as strong as the total predator effect and most importantly, as strong as the uncaged, "open" treatment with natural levels of predators. Our findings demonstrate that the mere presence of this fish reduces frond loss of the feather boa kelp through a trait-mediated trophic cascade. Moreover, despite large volumes of water, current flow, and wave energy, we clearly demonstrate a strong non-consumptive effect via an apparent chemical cue from señorita, suggesting that chemically mediated trait-driven cascades may be more prevalent in subtidal marine systems than we are currently aware.

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Section: Discussionmentioning

confidence: 99%

Fish predators reduce kelp frond loss via a trait‐mediated trophic cascade

Haggerty

Anderson

Long

2018

Ecology

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“…The latter usually involves changes in behaviour, physiology, and morphology mediated by chemical or visual cues from potential predators (Benard, ; Bourdeau & Johansson, ; Stoks, De Block, Van de Meutter, & Johansson, ). Such effects can have large impacts on the abundance and dynamics of populations (Abrams, ; Kimbro, Grabowski, Hughes, Piehler, & White, ). Knowledge of non‐consumptive effects can thus provide a mechanistic understanding of population structure.…”

Section: Introductionmentioning

confidence: 99%

Predation risk affects egg mortality and carry over effects in the larval stages in damselflies

2019

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The non‐consumptive predator effect may incur physiological costs that affect growth and development and ultimately survival. While studies have shown that the effect can affect development and growth in organisms with complex life cycles, we have limited knowledge on the effect in the egg and early larval stage. Here, we used a laboratory experiment to examine how the presence of chemical cues, a non‐consumptive predator effect, from an aquatic predator, perch, affected hatching success of larvae in three species of damselfly, Ischnura elegans, Coenagrion pulchellum, and Enallagma cyathigerum. In addition, we examined how exposure to predation risk in the early larval stages affected growth in the late larval stages of I. elegans. We found that the presence of chemical predator cues (1) increased egg mortality in all three species, (2) caused earlier hatching of eggs in one species, no change in a second species and a delay in egg hatching in a third species. We also found that predator cues have the potential to cause a carryover effect from early larval stages to late larval stages in terms of larval growth rate. The addition of non‐consumptive predator cues in the form of fish water caused higher algal growth than in the control experimental containers, and we suggest that this algal growth has the potential to confound predator stress cues. Our results show that the non‐consumptive predator effects affect survival and growth, and hence they have the potential to affect predator–prey dynamics in natural systems. Future studies on such effects in aquatic systems should consider confounding stressors, such as algae, fungi, oxygen, and nutrients levels, that might come with the addition of predation cues in water and thus add additional stress.

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“…In addition, the experiment would have to be conducted over multiple generations to allow time for the population trajectories to run their course and mitigate transitory effects on inference (Abrams 2008, Kimbro et al 2017. consumed in the natural treatment.…”

Section: The "Fear Removal" Treatment To Quantify Fear Effects In Wilmentioning

confidence: 99%

Quantifying fear effects on prey demography in nature

Peers

Majchrzak

Neilson

et al. 2018

Ecology

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In recent years, it has been argued that the effect of predator fear exacts a greater demographic toll on prey populations than the direct killing of prey. However, efforts to quantify the effects of fear have primarily relied on experiments that replace predators with predator cues. Interpretation of these experiments must consider two important caveats: (1) the magnitude of experimenter-induced predator cues may not be realistically comparable to those of the prey's natural sensory environment, and (2) given functional predators are removed from the treatments, the fear effect is measured in the absence of any consumptive effects, a situation which never occurs in nature. We contend that demographic consequences of fear in natural populations may have been overestimated because the intensity of predator cues applied by experimenters in the majority of studies has been unnaturally high, in some instances rarely occurring in nature without consumption. Furthermore, the removal of consumption from the treatments creates the potential situation that individual prey in poor condition (those most likely to contribute strongly to the observed fear effects via starvation or reduced reproductive output) may have been consumed by predators in nature prior to the expression of fear effects, thus confounding consumptive and fear effects. Here, we describe an alternative treatment design that does not utilize predator cues, and in so doing, better quantifies the demographic effect of fear on wild populations. This treatment substitutes the traditional cue experiment where consumptive effects are eliminated and fear is simulated with a design where fear is removed and consumptive effects are simulated through the experimental removal of prey. Comparison to a natural population would give a more robust estimate of the effect of fear in the presence of consumption on the demographic variable of interest. This approach represents a critical advance in quantifying the mechanistic pathways through which predation structures ecological communities. Discussing the merits of both treatments will motivate researchers to go beyond simply describing the existence of fear effects and focus on testing their true magnitude in wild populations and natural communities.

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Nonconsumptive effects of a predator weaken then rebound over time

Cited by 30 publications

References 49 publications

Fish predators reduce kelp frond loss via a trait‐mediated trophic cascade

Fish predators reduce kelp frond loss via a trait‐mediated trophic cascade

Predation risk affects egg mortality and carry over effects in the larval stages in damselflies

Quantifying fear effects on prey demography in nature

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