Trophic and spatial effects on the recovery of experimental metacommunities from severe stressors

Interactions trophiques
14:15, vendredi 20 déc. 2019 (15 minutes)
Salle EFG

Organisms are buffeted by biotic and abiotic factors that can significantly impact their ability to recover from sudden and/or prolonged changes to their environment. Recent theoretical work has suggested that trophic interactions combined with severe stress can either promote or inhibit the recovery of lower trophic levels, depending on the mechanism. Furthermore, spatial processes such as dispersal and the diffusion of nutrients could modify the trajectories of communities evolving in response to environmental stress. However, these earlier results are based on relatively simple conceptual models that are not tied to a specific system. At the Large Experimental Array of Ponds (LEAP) in the Gault Nature Reserve, 96 experimental ponds were exposed to a planned acidification treatment in order to investigate whether plankton communities could recover from the stress. In this talk, we present a phosphorus-multiple algae-multiple zooplankton meta-ecosystem model that explicitly considers ecophysiology and temperature sensitivity to help understand the biotic and abiotic processes at play in LEAP. Our results suggest that the zooplankton was severely affected by temperature, leading to a positive trophic cascade for the phytoplankton and suggests that stressors at LEAP promoted a faster recovery for phytoplankton to the pH shock. In addition, the movement of organisms and nutrients between experimental ponds had little impact on the metacommunity dynamics, though we present scenarios where it could have had an impact. Overall, our results indicates that integrating multiple stressors into models of community rescue is needed to make useful predictions about the trajectories of recovery.

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