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Biol Lett

Title:		Top predators suppress rather than facilitate plants in a trait-mediated tri-trophic cascade
Author(s):		Griffin JN; Butler J; Soomdat NN; Brun KE; Chejanovski ZA; Silliman BR;
Address:		"Department of Biology, University of Florida, Gainesville, FL, USA. johngriffin@ufl.edu"
Journal Title:		Biol Lett
Year:		2011
Volume:		20110420
Issue:		5
Page Number:		710 - 713
DOI:		10.1098/rsbl.2011.0166
ISSN/ISBN:		1744-957X (Electronic) 1744-9561 (Print) 1744-9561 (Linking)
Abstract:		"Classical ecological theory states that in tri-trophic systems, predators indirectly facilitate plants by reducing herbivore densities through consumption, while more recent work has revealed that predators can generate the same positive effect on plants non-consumptively by inducing changes in herbivore traits (e.g. feeding rates). Based on observations in US salt marshes dominated by vast monocultures of cordgrass, we hypothesized that sit-and-wait substrate-dwelling predators (crabs) could actually strengthen per capita impacts of potent grazers (snails), by non-consumptively inducing a vertical habitat shift of snails to their predation refuge high on canopy leaves that are vulnerable to grazing. A two-month field experiment supported this hypothesis, revealing that predators non-consumptively increased the mean climbing height of snails on grasses, increased grazing damage per leaf and ultimately suppressed cordgrass biomass, relative to controls. While seemingly counterintuitive, our results can be explained by (i) the vulnerability of refuge resources to grazing, and (ii) universal traits that drove the vertical habitat shift--i.e. relative habitat domains of predator and prey, and the hunting mode of the top predator. These results underline the fact that not only should we continue to incorporate non-consumptive effects into our understanding of top-down predator impacts, but we should do so in a spatially explicit manner"
Keywords:		Animals Crustacea/*physiology *Plant Physiological Phenomena *Predatory Behavior;
Notes:		"MedlineGriffin, John N Butler, Jack Soomdat, Nicole N Brun, Karen E Chejanovski, Zachary A Silliman, Brian R eng Research Support, U.S. Gov't, Non-P.H.S. England 2011/04/22 Biol Lett. 2011 Oct 23; 7(5):710-3. doi: 10.1098/rsbl.2011.0166. Epub 2011 Apr 20"