Direct versus indirect effects of temperature on community properties
Complex ecosystem dynamics pose challenges in determining whether the primary driver of plankton community changes is the temperature on organismal physiology (direct effects), predator-prey dynamics (indirect effects), or both. We conducted two sets of simulations to separate the direct and indirect effects of temperature; one where we exposed solely protists on the heatwave and one only on copepods. Looking at the biomass size bins, both copepods and protists show a variety of biomass anomalies depending on the temperature simulations (Figure 6). For copepods, functional diversity exhibits similar anomaly patterns between the initial heatwave simulations (which consider heatwave impacts on both protists and copepods’ physiology) and simulations where the heatwave solely affects copepods’ physiological rates while protists show more diverse anomaly patterns (Figure 3). The model outputs suggest that pinpointing a clear environmental driver becomes challenging as we move from individuals to populations, functional groups, and communities.