What are the end to end ecological models?

• Ecological models that focus on the ecosystem as a whole and take into account the interdependence of its components are sometimes called end-to-end models because they incorporate all ecosystem constituents from the dynamics of the abiotic environment to primary producers to top predators (Travers et al., 2007).
• There is a growing interest for the development of such models, which is at an early stage, driven by the worldwide movement toward ecosystem-based management and by the ever increasing appreciation of the complexity of the interacting factors that control ecosystem dynamics (Rose et al. 2010).
• In such models, the different elements of the ecosystem are linked together mainly through trophic interactions, i.e., by feeding (Moloney et al., 2011).
• Ideally, all these links between components are modeled bi-directionally (e.g., an increase in fish biomass due to feeding on zooplankton is also reflected in a decrease of zooplankton biomass). Such a two-way coupling of model elements allows to explicitly resolve at the same time both bottom-up and top-down mechanisms of ecological control.
• It is the combination of modeling these bidirectional links in the trophic structure and considering the dynamics of the environment that enables end-to-end models to provide long-term predictions on the development of fisheries ecosystems under environmental change (Johanson et al. 2017).
• In the context of ecosystem-based fisheries management, these predictive capabilities can be used to evaluate different management scenarios with regard to their long-term effectiveness (Stock et al., 2011).

Which are the advantages of 3D ecological models?

The main advantages of such full life cycle models are that they:

• Allow for straightforward linking of growth, mortality, movement and spawning processes to the detailed spatial and temporal scales of the hydrodynamic/biogeochemical model
• Can become more elaborated by adding new modules (e.g. top predator module, invasive alien species module, oil spill module)
• Can be used in multigenerational simulations in order to investigate (forecast) the effects of climate and fishing