Ecological Archives M083-005-A6

Pamela L. Reynolds, John F. Bruno. 2013. Multiple predator species alter prey behavior, population growth, and a trophic cascade in a model estuarine food web. Ecological Monographs 83:119–132. http://dx.doi.org/10.1890/11-2284.1

Appendix F. Effects of pinfish density on grazer feeding.

To assess whether predator density influences the strength of predator NCEs on prey grazing, on 22 August 2009 we placed female A. longimana in clear plastic cups with 50 mg Sargassum filipendula and exposed them to olfactory and visual cues from 0, 1, 3, or 6 pinfish in an outdoor water table (see Methods: Grazing Behavioral Experiment for description of replicate setup; n = 8) for 7 days. Pinfish density affected grazer feeding (nested one-way ANOVA; F3,28 = 22.22, P < 0.0001). Increasing pinfish density from 1 to 3 individuals per tub nonconsumptively reduced grazer feeding (LSM contrast, F1,28 = 18.04, P = 0.0002). There was no difference in grazing rate between the 3 and 6 pinfish treatments (LSM contrast, F1,28 = 0.04, P = 0.8440), indicating that the density-dependence of predator NCEs on their prey may attenuate at high predator densities (Fig. F1).

FigF1

 FIG. F1. Effects of predator density on prey grazing rate via nonconsumptive effects. (Values are means + 1 SE; comparisons are based on Tukey’s HSD.)


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