DEB-Storage: A Dynamic Energy Budget model for organisms in seasonally variable environments

The Dynamic Energy Budget (DEB) model provides a mechanistic framework for describing how organisms allocate energy to growth, maintenance, development and reproduction. The DEB model has been widely applied across taxa and environmental contexts; however, under seasonal food limitation, the standard formulation may predict insufficient reserve mobilization to meet somatic maintenance. The options to meet somatic maintenance in such cases, namely paying from structural tissue, resulting in shrinkage of body size, or paying from reproductive material, are unwanted for many species. To address this limitation, we propose a modified formulation, termed the DEB-Storage model, which introduces an additional energy storage compartment. This compartment provides an auxiliary energy pool that can be mobilized when reserves alone cannot meet maintenance demands, preventing unwanted structural shrinkage and avoiding depletion of reproductive tissue. The advantages of DEB-Storage and the storage compartment was demonstrated using a fish species ( Pleuronectes platessa ) under realistic seasonal forcing of temperature and food availability. The results show that compared to the standard DEB model, the DEB-Storage formulation reproduces observed seasonal patterns in growth, reproduction, and body condition more accurately, especially for juveniles that still lack reproductive material that can serve as energy source. Moreover, survival is prolonged when food is limited, resulting in more realistic periods individuals can sustain food scarcity . Overall, the DEB-Storage model provides a mechanistically consistent framework for modelling organisms in seasonal environments. • DEB-Storage extends the standard DEB model by explicitly representing energy storage. • DEB-Storage produces more realistic length–weight and body condition relationships. • DEB-Storage prevents unwanted structural shrinkage during energy deficits. • DEB-Storage extends survival in seasonal environments for adults and juveniles. • DEB-Storage can use existing Add-my-Pet parameter sets without full recalibration.