Experimental evidence for the desynchronization of ecosystem dynamics by global change

Understanding the coordinated response of ecosystems is fundamental to better apprehend ecosystem dynamics under environmental changes. Here, we conducted two independent mesocosms experiments to study how warming, nutrient enrichment, predator overexploitation, and their combination desynchronize freshwater ecosystems by studying high-frequency measurements of oxygen dynamics and of their cyclicity at different time scales (sub-daily to monthly). Nutrient enrichment desynchronized the whole dynamic of oxygen relative to control mesocosms and desynchronized oxygen cycles at all time scales, likely due to its effect on primary production. Warming and overexploitation only desynchronized oxygen cycles, especially at short-term, reflecting alteration of the diel rhythm of oxygen dynamic. Lastly, the combination of nutrient enrichment and warming dampened desynchronization, whereas the effects of nutrient enrichment were accentuated when combined with overexploitation. This first empirical evidence of global change impact on ecosystem synchrony opens important avenues to identify the destabilizing mechanisms of ecosystem functioning at uninvestigated spatio-temporal scales.

Methods
High frequency monitoring of oxygen during several months in two independant mesocosm experiments.