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Predator, prey and substrate interactions: the role of faunal activity and substrate characteristics

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posted on 18.01.2019 by Kate Mathers, Stephen Rice, Paul Wood
Many taxa possess a range of strategies to reduce the risk of predation, including actively seeking suitable refuge habitats; however, the global spread of invasive species may disrupt these behavioral responses. In lotic ecosystems, interstitial spaces in the substrate are important refugia for small organisms. Some predators are ecosystem engineers that exhibit zoogeomorphic agency—the ability to modify the geomorphology of their environment. It is therefore possible that direct ecological effects of predators on prey may be realized through modifications to the prey's habitat, including the availability of refugia, by predators that are zoogeomorphic agents or via external stressors such as fine sediment loading. This study examined three research questions in a mesocosm study across a gradient of sediment‐stress treatments: (1) What affects do predators (Pacifastacus leniusculus, invasive crayfish) and prey (Gammarus pulex, amphipods) have on the ingress of fine sediment into gravel substrates and therefore on available interstitial refugia? (2) Do prey taxa seek refuge from (invasive) predators in the form of vertical movement into subsurface sediments? and (3) How does fine sediment ingress influence predator–prey interactions and prey survival through predator avoidance behavior. Here, we provide direct evidence demonstrating that fine sediment ingress into gravel river beds can be facilitated by zoogeomorphic activity with P. leniusculus increasing the infiltration of fine sand particles (but not coarse sand) during foraging activities. Predator–prey interactions were found to be a primary factor mediating zoogeomorphic activity, with the isolation of crayfish from prey (G. pulex) leading to increased fine sand ingress. When present with signal crayfish, G. pulex displayed vertical avoidance behavior, entering subsurface substrates to evade predation by P. leniusculus. Coarse sand treatments resulted in higher predation rates of G. pulex, most likely due to clogging of interstitial pore spaces between gravels limiting the effectiveness of the prey's vertical avoidance behavior strategy. A new conceptual model that captures the interactions between predator, prey, zoogeomorphic processes and habitat availability is presented. This model highlights how predator–prey interactions can be strongly mediated by dynamic bi‐directional interactions between organisms and the physical environment they inhabit as ecological and geomorphological processes are intrinsically linked.

Funding

KLM acknowledges the support of a Glendonbrook doctoral studentship and co‐funding from the Environment Agency to undertake this study.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Ecosphere

Citation

MATHERS, K.L., RICE, S.P. and WOOD, P.J., 2019. Predator, prey and substrate interactions: the role of faunal activity and substrate characteristics. Ecosphere, 10 (1), e02545.

Publisher

Ecological Society of America © The Authors

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Acceptance date

12/01/2018

Publication date

2019

Notes

This is an open access article under the terms of the Creative Commons Attribution 4.0 International License (CC BY), which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

ISSN

2150-8925

Language

en

Licence

Exports