Restricting Prey Dispersal Can Overestimate the Importance of Predation in Trophic Cascades

Geraldi, NR; Macreadie, PI

Restricting Prey Dispersal Can Overestimate the Importance of Predation in Trophic Cascades

Geraldi, NR Macreadie, PI

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Publication Type:: Journal Article
Citation:: PLoS ONE, 2013, 8 (2)
Issue Date:: 2013-02-07

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Field	Value	Language
dc.contributor.author	Geraldi, NR	en_US
dc.contributor.author	Macreadie, PI https://orcid.org/0000-0001-7362-0882	en_US
dc.date.available	2012-12-22	en_US
dc.date.issued	2013-02-07	en_US
dc.identifier.citation	PLoS ONE, 2013, 8 (2)	en_US
dc.identifier.uri	http://hdl.handle.net/10453/35866
dc.identifier.uri	http://hdl.handle.net/10453/23982
dc.description.abstract	Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish - Opsanus tau), prey (mud crab - Panopeus herbstii) and resource (ribbed mussel - Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured. © 2013 Geraldi, Macreadie.	en_US
dc.relation.ispartof	PLoS ONE	en_US
dc.relation.isbasedon	10.1371/journal.pone.0055100	en_US
dc.subject.classification	General Science & Technology	en_US
dc.subject.mesh	Animals	en_US
dc.subject.mesh	Predatory Behavior	en_US
dc.subject.mesh	Ecology	en_US
dc.title	Restricting Prey Dispersal Can Overestimate the Importance of Predation in Trophic Cascades	en_US
dc.type	Journal Article
utslib.citation.volume	2	en_US
utslib.citation.volume	8	en_US
utslib.for	0602 Ecology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
utslib.copyright.status	open_access
pubs.issue	2	en_US
pubs.publication-status	Published	en_US
pubs.volume	8	en_US

Abstract:

Predators can affect prey populations and, via trophic cascades, predators can indirectly impact resource populations (2 trophic levels below the predator) through consumption of prey (density-mediated indirect effects; DMIEs) and by inducing predator-avoidance behavior in prey (trait-mediated indirect effects; TMIEs). Prey often employ multiple predator-avoidance behaviors, such as dispersal or reduced foraging activity, but estimates of TMIEs are usually on individual behaviors. We assessed direct and indirect predator effects in a mesocosm experiment using a marine food chain consisting of a predator (toadfish - Opsanus tau), prey (mud crab - Panopeus herbstii) and resource (ribbed mussel - Geukensia demissa). We measured dispersal and foraging activity of prey separately by manipulating both the presence and absence of the predator, and whether prey could or could not disperse into a predator-free area. Consumption of prey was 9 times greater when prey could not disperse, probably because mesocosm boundaries increased predator capture success. Although predator presence did not significantly affect the number of crabs that emigrated, the presence of a predator decreased resource consumption by prey, which resulted in fewer resources consumed for each prey that emigrated in the presence of a predator, and reduced the overall TMIE. When prey were unable to disperse, TMIEs on mussel survival were 3 times higher than the DMIEs. When prey were allowed to disperse, the TMIEs on resource survival increased to 11-times the DMIEs. We found that restricting the ability of prey to disperse, or focusing on only one predator-avoidance behavior, may be underestimating TMIEs. Our results indicate that the relative contribution of behavior and consumption in food chain dynamics will depend on which predator-avoidance behaviors are allowed to occur and measured. © 2013 Geraldi, Macreadie.

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http://hdl.handle.net/10453/23982