Historical processes are imprinted in current responses of ecosystems, a phenomenon known as ecological memory. Understanding how climatic changes, such as more frequent extreme climatic events (ECEs), alter ecosystems' memory is becoming increasingly important. However, while there has been a growing interest in projecting biodiversity and ecosystem functioning under future climate scenarios, how legacy effects originating from historical conditions drive change in ecosystems remained largely unexplored. Here we evaluated the response of rocky intertidal epilithic microphytobenthos (EMPB) to manipulation of the identity, order of occurrence and degree of temporal clustering of extreme warming and sediment deposition events. We used the Stochastic Antecedent Modelling (SAM) approach to integrate experimental ECEs as historical events and assess how they interact with past environmental conditions, modulating ecological memory of EMPB.
Results/Conclusions
We found memory effects in the non-clustered scenario of disturbance (60 days apart), where EMPB biomass fluctuated in time, but not under clustered disturbances (15 days apart), where EMPB biomass was consistently low. A massive grazing event impacted on EMPB biomass in a second run of the experiment, also muting ecological memory. Our results provide empirical support to the theoretical expectation that stochastic fluctuations promote ecological memory, but also show that contingencies may lead to memory loss. In conclusion, our findings point to the need of new studies aimed at investigating the role of ecological memory in modulating the interaction between biotic processes and increased climate variability.