Indirect effects of ecosystem engineering combine with consumer behaviour to determine the spatial distribution of herbivory

Abstract

Ecosystem engineers alter environments by creating, modifying or destroying habitats. The indirect impacts of ecosystem engineering on trophic interactions should depend on the combination of the spatial distribution of engineered structures and the foraging behaviour of consumers that use these structures as refuges. In this study, we assessed the indirect effects of ecosystem engineering by a wood-boring beetle in a neotropical mangrove forest system. We identified herbivory patterns in a dwarf mangrove forest on the archipelago of Twin Cays, Belize. Past wood-boring activity impacted more than one-third of trees through the creation of tree holes that are now used, presumably as predation or thermal refuge, by the herbivorous mangrove tree crab Aratus pisonii. The presence of these refuges had a significant impact on plant-animal interactions; herbivory was more than fivefold higher on trees influenced by tree holes relative to those that were completely isolated from these refuges. Additionally, herbivory decreased exponentially with increasing distance from tree holes. We use individual-based simulation modelling to demonstrate that the creation of these herbivory patterns depends on a combination of the use of engineered tree holes for refuge by tree crabs, and the use of two behaviour patterns in this species-site fidelity to a "home tree," and more frequent foraging near their home tree. We demonstrate that understanding the spatial distribution of herbivory in this system depends on combining both the use of ecosystem engineering structures with individual behavioural patterns of herbivores.

Introduced marine ecosystem engineer indirectly affects parasitism in native mussel hosts

“…Overall, the results of our study suggest that invasive ecosystem engineers can exert TMIEs on parasites, which is a novel mechanism of how invasive species can affect recipient ecosystems. Given the increasing evidence that ecosystem engineers in general can exert manifold indirect effects on species interactions and food webs (White and O'Donnell 2010;Sanders et al 2014;Wetzel et al 2016;Griffen et al 2017;Mourant et al 2017), it seems highly likely that many of these indirect effects will also trigger TMIEs (and also DMIEs) on parasites if they include changes in the behaviour or density of species that serve as hosts for parasites. Hence, indirect effects of invasive ecosystem engineers on parasite-host interactions in recipient ecosystems may be much more common than realized today and they possibly add significantly to the known diversity of impacts of invasive ecosystems engineers (Crooks 2002;Guy-Haim et al 2018).…”

Ecosystem engineers shape ecological network structure and stability: A framework and literature review

“…Orwin et al, 2016), depending on who benefits. The beetle Elaphidion mimeticum creates holes on mangrove trees that can be subsequently used as refuges by mangrove tree crabs, Aratus pisonii, leading to an increase in crab herbivory on mangrove plants (Griffen et al, 2017). Gall forming species on plants often provide shelter for natural enemies, thereby increasing top-town control.…”