Simulation of trait- and density-mediated indirect effects induced by piscivorous predators

Authored by F Holker, T Mehner

Date Published: 2005

DOI: 10.1016/j.baae.2004.10.001

Sponsors: German Research Foundation (Deutsche Forschungsgemeinschaft, DFG)

Platforms: No platforms listed

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

The study demonstrates how to use a spatially explicit individual-based model (IBM) to tackle the problem of resolving density-mediated (DMII) and trait-mediated indirect interactions (TMII) when manipulative experimentation is difficult on the scale of community-level interactions in the real word. As an example we simulated predator-induced behavioural changes in a roach (Rutilus rutilus (L.)) population before and after stocking a take with an additional pelagic predator (Sander lucioperca (L.)). By this it was possible to calculate bioenergetic gains and costs of trait changes as well as the relative proportions of DMIIs and TMIIs in roach consumption on littoral and pelagic resources in the take food web. Despite higher net activity costs of 64\%, roach migrating horizontally over the diet cycle had a net benefit (higher energy intake of 75\%) compared to roach that were restricted to the littoral as a behavioural response to the new predator. By separating the components of the indirect predator effects, we demonstrate that a predator-induced modification in prey traits (behaviour, feeding activity) could contribute substantially to the net indirect effect of a predator even when there are strong density effects. When considering the predation pressure by roach on pelagic resources, the net TMIIs due to the behavioural adaptation of the consumer in response to the predator were 13-14 times stronger than the DMIIs atone. When comparing the different effects on littoral resources it can be shown that the TMIIs approximately compensate the DMIIs thus resulting in a nearly zero net effect. (c) 2004 Elsevier GmbH. All rights reserved.

Tags

Competition Habitat use population growth Diet Resources Lakes Rutilus-rutilus l Zooplankton consumption Roach