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.