Resource co-limited growth in fluctuating environments

Variability in the supply of limiting resources determines consumer-resource interactions. Yet, how consumers are affected by variability when multiple resources co-limit growth remains unknown. We use a two-resource DEB model to predict how consumer somatic growth rate responds to the temporal structure (i.e. fluctuation frequency, phase and covariance) of single and co-limiting resources supply. Subsequently, we experimentally test the model predictions using Daphnia magna (co-)limited by dietary phosphorus and cholesterol supply. Both model and experiments indicate that for certain fluctuation frequencies, resource fluctuation phase and (co)variance can heavily affect somatic growth. The model suggests that dynamic resource storage and assimilation efficiency adjustment are key for predicting the frequencies at which the growth rate is mostly affected by (co)variance and phase. In a context of ongoing anthropogenic landscape homogenization, our results offer novel insights on how co-occurring perturbations to the temporal structure of resource supply can affect consumer performance.