Behaviorally Mediated Trophic Cascades: Effects of Predation Risk on Food Web Interactions

Schmitz, Oswald J.; Beckerman, Andrew P.; O’Brien, Kathleen

doi:10.2307/2266134

Cited by 277 publications

(380 citation statements)

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“…Previous research consistently showed that grasshoppers preferentially exploit nutritionally superior grasses, and can inflict considerable damage to them when P. mira is absent (13-16). P. mira presence consistently causes grasshoppers to forego feeding on grasses and to seek refuge in leafy herbs, resulting in high damage levels to herbs (13)(14)(15)(16). This shift in resource use by grasshoppers results in a positive indirect effect of the spider on grasses and a detrimental, negative indirect effect on herbs.…”

Section: Methodsmentioning

confidence: 99%

“…We examined interactions among those plants, the grasshopper herbivore Melanoplus femurrubrum, and an important predator of the grasshopper (13), the sit-and-wait hunting spider Pisaurina mira. Previous research consistently showed that grasshoppers preferentially exploit nutritionally superior grasses, and can inflict considerable damage to them when P. mira is absent (13)(14)(15)(16). P. mira presence consistently causes grasshoppers to forego feeding on grasses and to seek refuge in leafy herbs, resulting in high damage levels to herbs (13)(14)(15)(16).…”

Section: Methodsmentioning

confidence: 99%

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Linking individuals with ecosystems: Experimentally identifying the relevant organizational scale for predicting trophic abundances

Ovadia

Schmitz

2002

Proc. Natl. Acad. Sci. U.S.A.

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Ecosystems are complex owing to the fact that emergent properties like trophic structure and productivity depend on details related to lower-scale interactions among individuals. A key challenge is identifying how much individual-level detail is needed to predict patterns at the ecosystem level. We tested for the effect of individual herbivore body size on trophic interactions and consequent abundances of plant and herbivore trophic levels in a New England meadow ecosystem. Body size is an important determinant of vulnerability to predation and thus should influence the way individuals tradeoff time spent foraging against time spent avoiding contact with predators. Such tradeoffs can then influence the degree of damage herbivores inflict on their plant resources. We experimentally assigned field-caught grasshoppers to three distinct body size treatment groups (small, normal, and large) and crossed them with two spider predator treatments (spider present and absent) in a fully replicated design. We observed size-dependent differences in grasshopper survival and development. Moreover, predators caused grasshoppers to inflict greater damage to herbs and lesser damage to grasses relative to treatments without predators. However, there were no size-dependent differences in net damage level on grasses and herbs in either predator or no predator treatments owing to size-dependent compensation in grasshopper foraging effort. We thus conclude that in this ecosystem the foraging-predation risk tradeoff displayed by typical or average-sized herbivore is a sufficient amount of individual-level detail needed to explain ecosystem patterns.size-dependent predation risk ͉ herbivore-mediated trophic effects ͉ old-field ecosystem ͉ grasshoppers ͉ trait-mediated indirect effects E cosystems are paradigmatically complex. They contain many different components that interact directly and indirectly in integrated networks (1, 2). In such complex networks, higher scale system properties like trophic structure, nutrient fluxes, and productivity emerge from lower scale interactions and selection among components (1, 2). Furthermore, feedback loops in which higher scale properties modify lower-scale interactions cause new emergent properties to arise over time (1, 2). A central problem is identifying which lower scale processes should be included in theory aiming to predict higher-scale properties of ecosystems.Classical ecology (e.g., refs. 3-6) has approached this problem by assuming that it is sufficient to abstract lower scale details, such as interactions among individuals in populations, and characterize ecosystem function simply in terms of net changes in numbers or densities of individuals at the level of whole populations. Abstracting such individual-scale detail is reasonable if the effects of individual-level interactions attenuate on the time scale of changes in population density. However, the assumption that individual-scale detail can be safely abstracted is increasingly being called into question (7). Populations are effec...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Linking individuals with ecosystems: Experimentally identifying the relevant organizational scale for predicting trophic abundances

Ovadia

Schmitz

2002

Proc. Natl. Acad. Sci. U.S.A.

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“…Predators often have profound impacts on prey populations and on the organization and function of communities in general (Paine, 1966;Carpenter et al, 1985;Schmitz et al, 1997;Schmitz, 1998;Menge, 2000). The overall effect of predators on communities is determined by interactions between individual predators and prey (Lima, 1998(Lima, , 2002.…”

Section: Introductionmentioning

confidence: 99%

“…Prey may minimize predator avoidance costs by using flexible avoidance strategies that balance the frequency or magnitude of predator avoidance responses with a perceived level of risk (Sih et al, 1985;Schmitz et al, 1997;Schmitz, 1998;Chivers and Smith, 1998;Katz and Dill, 1998;McIntosh and Peckarsky, 1999). Thus, prey require stimuli that accurately reveal the level of risk to determine when and how predator avoidance strategies should be employed.…”

Section: Introductionmentioning

confidence: 99%

Hard Clams (Mercenaria mercenaria) Evaluate Predation Risk Using Chemical Signals from Predators and Injured Conspecifics

2006

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Abstract-Hard clams, Mercenaria mercenaria, are sessile, filter-feeding organisms that are heavily preyed upon by blue crabs, which find their clam prey using chemical cues. Clams may evade blue crabs by reducing their pumping (feeding) behavior when a threat is perceived. The purpose of this study was to determine the type of signals that clams use to detect consumers. Clams decreased their pumping time in response to blue crabs and blue crab effluent, but not to crab shells, indicating that chemical signals and not mechanical cues mediated the response of clams to distant predators. Because predator diet can influence prey evaluation of predatory threats, we compared clam responses to blue crabs fed a steady diet of fish, clams, or that were starved prior to the experiment. In addition, we used injured clams as a stimulus because many organisms detect predators by sensing the odor of injured con-or heterospecifics. Clams reduced feeding in response to injured conspecifics and to blue crabs that had recently fed. Clams reacted similarly to fed crabs, regardless of their diet, but did not respond to starved blue crabs. Because blue crabs are generalist predators and the threat posed by these consumers is unrelated to the crab's diet, we should expect clam reactions to blue crabs to be independent of the crab's diet. The failure of clams to react to starved blue crabs likely increases their vulnerability to these consumers, but clam responses to injured conspecifics may constitute a strategy that allows animals to detect an imminent threat when signals emanating from blue crabs are not detectable.

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“…These latter responses, termed nonconsumptive effects (NCEs), may have an equal or larger impact on community structure than consumptive effects (Peacor and Werner 2001, Preisser et al 2005). For instance, behavioral avoidance of predators can potentially impact prey habitat use, foraging rates, energy allocation and ultimately population dynamics (e.g., Schmitz et al 1997, Grabowski 2004, Schmitz et al 2004. The strength of NCEs can be context dependent, and is influenced by both biotic and abiotic processes.…”

Section: Introductionmentioning

confidence: 99%

Ecological and socioeconomic implications of a northern range expansion of black sea bass, Centropristis striata

McMahan¹

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Behaviorally Mediated Trophic Cascades: Effects of Predation Risk on Food Web Interactions

Cited by 277 publications

References 0 publications

Linking individuals with ecosystems: Experimentally identifying the relevant organizational scale for predicting trophic abundances

Linking individuals with ecosystems: Experimentally identifying the relevant organizational scale for predicting trophic abundances

Hard Clams (Mercenaria mercenaria) Evaluate Predation Risk Using Chemical Signals from Predators and Injured Conspecifics

Ecological and socioeconomic implications of a northern range expansion of black sea bass, Centropristis striata

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