Contrasting seasonal dynamics of pelagic and benthic invertebrates scale with lake productivity

Key points:* Limnology has focused on open-water periods, leaving major gaps in understanding annual biological dynamics * Opposing seasonal dominance of pelagic and benthic invertebrates strengthens with lake productivity * Seasonal variation in phytoplankton, zooplankton, and benthos abundance scales with lake productivity at similar rates Abstract: Seasonal variation in environmental conditions drives pronounced shifts in animal abundance and community composition throughout the year.However, limnology has historically emphasized the openwater period, overlooking the ice cover period and leaving major gaps in understanding annual ecosystem dynamics.Here, we compiled seasonal abiotic and biotic data from 78 seasonally freezing lakes to evaluate full-year patterns in zooplankton and benthic communities.We show that winter reorganizes lake food webs in parallel but opposing ways across pelagic and benthic habitats, with a contrasting seasonal dominance that strengthens along lake productivity gradients.Seasonal variation in zooplankton and benthos abundance scales with lake productivity at similar rates, likely due to the interaction between nutrient and light limitation across lakes.Together, these results highlight the important role that winter plays in annual ecosystem processes, provide a framework for testing annual lake biological dynamics, and suggest hypotheses about the interactions between seasonality and productivity across ecosystems.