Warming amplifies short-term responses to disturbance in lake food webs

Abstract

Ecological communities can exhibit transient amplification after disturbance even if asymptotically stable, yet how environmental change reshapes these short-term responses in real food webs remains unclear. We combined four decades of monthly plankton observations from nine Swiss lakes with a food-web model to quantify effects of warming and oligotrophication on two transient properties: reactivity (instantaneous sensitivity to small disturbances) and the time to peak response (tmax). Across lakes, community states lie in an asymptotically stable yet reactive regime. Warmer conditions consistently increased reactivity and lengthened tmax; after accounting for oligotrophication, a 1 {degrees}C rise in mean temperature corresponded to [~] 10% higher reactivity on average. Linking month-to-month variation in transient metrics to guild biomass showed that reactivity covaried strongly with consumer biomass, especially large herbivores, whereas tmax was most associated with predator biomass, a pattern consistent with metabolic-scaling predictions from thermal ecology. The central warming-reactivity association was preserved when we made the bioenergetic parameters themselves temperature-dependent through Boltzmann-Arrhenius scaling. Warming therefore systematically boosted transient sensitivity in these lake food webs via shifts in consumer and predator biomass. Author summaryEcological stability is often evaluated using long-term equilibrium properties that describe whether a community eventually returns toward its previous state after a disturbance, and how long this recovery takes. Yet a system that is stable in the long run can still undergo a strong short-term response before recovering. We asked whether environmental warming changes the magnitude and duration of these temporary responses in real ecosystems. We combined four decades of monthly plankton observations from nine Swiss lakes with a mathematical model describing interactions among major feeding groups. We found that warmer conditions were consistently associated with stronger responses to disturbance and with a longer delay before those responses reached their maximum. These patterns emerged despite the communities remining stable over the long term. Changes in the amount of biomass held by consumers and predators helped explain the observed responses, suggesting that warming alters stability through changes in food-web structure. Our findings show that long-term measures alone may overlook ecologically important short-term dynamics. Considering both eventual recovery and temporary amplification could therefore improve our understanding of how lakes and other ecosystems respond to ongoing climate change and increasingly frequent disturbances.