Journal Article

RESOURCE IDENTITY MODIFIES THE INFLUENCE OF PREDATION RISK ON ECOSYSTEM FUNCTION

Trussell, Geoffrey C., Ewanchuk, Patrick J., Matassa, Catherine M.

2008

Overview

It is well established that predators can scare as well as consume their prey. In many systems, the fear of being eaten causes trait-mediated cascades whose strength can rival or exceed that of more widely recognized density-mediated cascades transmitted by predators that consume their prey. Despite this progress it is only beginning to be understood how the influence of predation risk is shaped by environmental context and whether it can exert an important influence on ecosystem-level processes. This study used a factorial mesocosm experiment that manipulated basal-resource identity (either barnacles, Semibalanus balanoides, or mussels, Mytilus edulis) to determine how resources modify the influence of predation risk, cascade strength, and the efficiency of energy transfer in two, tritrophic, rocky-shore food chains containing the predatory green crab (Carcinus maenas) and an intermediate consumer (the snail, Nucella lapillus). The effect of predation risk and the strength of trait-mediated cascades (both in absolute and relative terms) were much stronger in the barnacle than in the mussel food chain. Moreover, predation risk strongly diminished the efficiency of energy transfer in the barnacle food chain but had no significant effect in the mussel food chain. The influence of resource identity on indirect-effect strength and energy transfer was likely caused by differences in how each resource shapes the degree of risk perceived by prey. We suggest that our understanding of the connection between trophic dynamics and ecosystem functioning will improve considerably once the effects of predation risk on individual behavior and physiology are considered.

• Publisher: Ecological Society of America
• Subject: Animal and plant ecology / animal behavior / Animal ecology / Animal, plant and microbial ecology / Animals / aquatic ecosystems / aquatic invertebrates / barnacle cf. mussel food chain / Biological and medical sciences / Bivalvia / Bivalvia - growth & development / Bivalvia - physiology / Brachyura / Brachyura - growth & development / Brachyura - physiology / Carcinus maenas / Cirripedia / consumptive and nonconsumptive effects / Decapoda / density-mediated effects / Ecology / Ecosystem / ecosystem function / Ecosystems / energy metabolism / energy transfer / Food Chain / food webs / Foraging / Fundamental and applied biological sciences. Psychology / Gastropoda / General aspects / growth & development / Invertebrates / Marine / Marine ecology / mesocosm experiment / Mollusca / Mussels / Mytilus edulis / Natural resources / Nucella lapillus / physiology / Population Density / Population Dynamics / predation / predation risk perception / predator-prey relationships / Predators / Predatory Behavior / Predatory Behavior - physiology / resource identity / risk assessment / Semibalanus balanoides / Snails / Snails - growth & development / Snails - physiology / Synecology / Thoracica / Thoracica - growth & development / Thoracica - physiology / trait-mediated effects / tritrophic rocky-shore food chains / trophic cascade / trophic cascades / trophic relationships