title: Pathogens trigger top-down climate forcing on ecosystem dynamics.
abstract: Evaluating the effects of climate variation on ecosystems is of paramount importance for our ability to forecast and mitigate the consequences of global change. However, the ways in which complex food webs respond to climate variations remain poorly understood. Here, we use long-term time series to investigate the effects of temperature variation on the intraguild-predation (IGP) system of Windermere (UK), a lake where pike (Esox lucius, top predator) feed on small-sized perch (Perca fluviatilis) but compete with large-sized perch for the same food sources. Spectral analyses of time series reveal that pike recruitment dynamics are temperature controlled. In 1976, expansion of a size-truncating perch pathogen into the lake severely impacted large perch and favoured pike as the IGP-dominant species. This pathogen-induced regime shift to a pike-dominated IGP apparently triggered a temperature-controlled trophic cascade passing through pike down to dissolved nutrients. In simple food chains, warming is predicted to strengthen top-down control by accelerating metabolic rates in ectothermic consumers, while pathogens of top consumers are predicted to dampen this top-down control. In contrast, the local IGP structure in Windermere made warming and pathogens synergistic in their top-down effects on ecosystem functioning. More generally, our results point to top predators as major mediators of community response to global change, and show that size-selective agents (e.g. pathogens, fishers or hunters) may change the topological architecture of food webs and alter whole ecosystem sensitivity to climate variation.
authors.affiliation: Institut d'Ecologie et des Sciences de l'Environnement-Paris (iEES-Paris), Sorbonne Universités/UPMC Université Paris 06/CNRS/INRA/IRD/Paris Diderot Université Paris 07/UPEC, 7 quai St Bernard, 75252, Paris, France. eric.edeline@upmc.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Edeline
authors.affiliation: Environmental Research and Teaching Institute (CERES-ERTI), Ecole Normale Supérieure, 24 Rue Lhomond, 75230, Paris Cedex 05, France.|Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA, 90095-1565, USA.
authors.forename: Andreas
authors.initials: A
authors.lastname: Groth
authors.affiliation: IRD-UPMC, UMI 209 UMMISCO, 93143, Bondy, France.|Eco-Evolutionary Mathematics, UMR 8197, Ecole Normale Superieure, 46 rue d'Ulm, 75230, Paris Cedex 05, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Cazelles
authors.affiliation: Environmental Research and Teaching Institute (CERES-ERTI), Ecole Normale Supérieure, 24 Rue Lhomond, 75230, Paris Cedex 05, France.|Eco-Evolutionary Mathematics, UMR 8197, Ecole Normale Superieure, 46 rue d'Ulm, 75230, Paris Cedex 05, France.
authors.forename: David
authors.initials: D
authors.lastname: Claessen
authors.affiliation: Lake Ecosystems Group, Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP, UK.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Winfield
authors.affiliation: Department of Biosciences, Center for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066, Blindern, 0316, Oslo, Norway.|School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, 98195, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Ohlberger
authors.affiliation: Department of Biosciences, Center for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066, Blindern, 0316, Oslo, Norway.
authors.forename: L
authors.initials: L
authors.lastname: Asbjørn Vøllestad
authors.affiliation: Department of Biosciences, Center for Ecological and Evolutionary Synthesis (CEES), University of Oslo, P.O. Box 1066, Blindern, 0316, Oslo, Norway.
authors.forename: Nils C
authors.initials: NC
authors.lastname: Stenseth
authors.affiliation: Environmental Research and Teaching Institute (CERES-ERTI), Ecole Normale Supérieure, 24 Rue Lhomond, 75230, Paris Cedex 05, France.|Department of Atmospheric and Oceanic Sciences and Institute of Geophysics and Planetary Physics, University of California at Los Angeles, Los Angeles, CA, 90095-1565, USA.|Laboratoire de Météorologie Dynamique, CNRS and IPSL, 24 Rue Lhomond, 75230, Paris Cedex 05, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Ghil
mesh_terms: D000818:Animals; D002980:Climate; D017753:Ecosystem; D017859:Esocidae; D020387:Food Chain; D011157:Population Dynamics; D011235:Predatory Behavior
keywords: Body size; Parasites; Population structure; Singular spectrum analysis; Wavelet analysis