A heatwave event modulates consumer-producer synchrony and stability in a freshwater plankton community

Global Change
Partie de:
jeudi 19 déc. 02:55 PM (15 minutes)
Salle ABCD
Predicting the direction and magnitude of ecosystem responses to extreme event forcing, is central to our understanding of the thermal thresholds and limits that sustain healthy and productive biological assemblages. In freshwater environments, extreme heatwave events can modulate producer-consumer (a)synchrony and plankton phenology, but they can also reduce primary production and promote the occurrence of algal blooms. We used data on the dynamics of semi-natural phytoplankton and zooplankton communities from two whole-pond mesocosm experiments (2017 and 2018) at the LEAP platform located at the McGill Gault Reserve (Mont Saint Hilaire, Qc.). We investigated the influence of a decadal heatwave event to test the relative strength of top-down control on phytoplankton biomass and producer-consumer (a)synchrony. We find significant synchronous responses of primary consumers maintained by asynchronous thermal compensation dynamics of phytoplankton groups sustaining excess heat. We found that temporal correlations in low diversity algal communities tended to destabilize the ecosystem biomass under heatwave conditions. We conclude that strong temperature anomalies that characterise summer heatwaves can modulate top-down versus bottom-up ecological effects in plankton communities. These events are therefore particularly suitable to study in order to better quantify how ecosystems respond to strong temperature anomalies largely driven by climate change.

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