HORIZONS Mismatch revisited: what is trophic mismatching from the perspective of the plankton?

Long-term changes in the seasonal timing of phytoplankton and zooplankton population development (i.e. phenological changes) have been widely reported in freshwater and marine ecosystems, and have been interpreted as a biological response to ongoing climate change. Observed among-species variations in the rates and patterns of these changes have led to concerns that seasonal trophic interactions may become de-synchronized in plankton communities, following the logic of the match–mismatch hypothesis. Herein, the current evidence for long-term mismatching within plankton communities is evaluated and the meaning of this concept for the plankton is explored. Despite the large number of studies documenting phenological change in plankton communities, very few explicitly quantify mismatching among trophic levels within the same study system, and quantify its ecological impacts. There is a clear need to build the evidence base for the mismatching phenomenon. In this endeavour, we must carefully define the seasonality of resource availability based on prior ecological knowledge, and embrace the challenges posed by organisms with more complex life cycles and the ecological network context within which plankton interact. In addition, we must acknowledge that, while mismatching in the plankton and in non-planktonic systems relates to synchrony between resource supply and consumer demand, there are conceptual differences in the phenomenon between these two broad classes of systems. For planktonic systems, mismatching is best visualized as an alteration of the rates and lags of the interaction between dynamically linked consumers and resources, rather than simple and independent phase shifts of seasonal abundance peaks at each trophic level.